WorldWideScience

Sample records for voltage dc method

  1. Triple voltage dc-to-dc converter and method

    Science.gov (United States)

    Su, Gui-Jia

    2008-08-05

    A circuit and method of providing three dc voltage buses and transforming power between a low voltage dc converter and a high voltage dc converter, by coupling a primary dc power circuit and a secondary dc power circuit through an isolation transformer; providing the gating signals to power semiconductor switches in the primary and secondary circuits to control power flow between the primary and secondary circuits and by controlling a phase shift between the primary voltage and the secondary voltage. The primary dc power circuit and the secondary dc power circuit each further comprising at least two tank capacitances arranged in series as a tank leg, at least two resonant switching devices arranged in series with each other and arranged in parallel with the tank leg, and at least one voltage source arranged in parallel with the tank leg and the resonant switching devices, said resonant switching devices including power semiconductor switches that are operated by gating signals. Additional embodiments having a center-tapped battery on the low voltage side and a plurality of modules on both the low voltage side and the high voltage side are also disclosed for the purpose of reducing ripple current and for reducing the size of the components.

  2. Analytical Method to Calculate the DC Link Current Stress in Voltage Source Converters

    DEFF Research Database (Denmark)

    Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand; Teodorescu, Remus;

    2014-01-01

    The dc-link capacitor is one of the critical components, which influences the lifetime of the whole voltage source converter unit. For reliable design, the operating temperature of the dc-link capacitor should be known, which is primarily determined by the ambient temperature and the rms value...... of the current flowing through the dc-link capacitor. A simple analytical method to calculate the rms value of the dc-link capacitor current is presented in this paper. The effect of the line current ripple on the rms value of the dc-link capacitor current is considered. This yields accurate results, especially...

  3. Characterization of (100)-orientated diamond film grown by HFCVD method with a positive DC bias voltage

    Institute of Scientific and Technical Information of China (English)

    MA Ying; WANG Lin-jun; LIU Jian-min; SU Qing-feng; XU Run; PENG Hong-yan; SHI Wei-min; XIA Yi-ben

    2006-01-01

    The (100)-orientated diamond film was deposited by hot-filament chemical vapor deposition (HFCVD) technology with a positive DC bias voltage. The morphology,X-ray diffraction (XRD),RAMAN spectrum and dark current versus applied voltage characteristics analysis show that the positive dc bias can increase the nucleation density and (100)-orientated growth,making the growth of the high quality diamond film easier and cheaper than using other methods.

  4. Electrooptic Methods for Measurement of Small DC Currents at High Voltage Level

    DEFF Research Database (Denmark)

    Tønnesen, Ole; Beatty, Neville; Skilbreid, Asbjørn Ottar

    1989-01-01

    . The measuring methods can be used both for development and supervision of electrical insulating systems. For DC measurements a system wherein the voltage is applied (across the Pockels cell) not directly but via an electrooptic circuit was developed. This circuit periodically inverts the polarity of the voltage...... fibre to an electrooptic converter. Second, by use of an electronic circuit the measured signal can be converted into a modulated frequency form for transmission along an optical fibre. These systems are described, measurement results are presented and improvements to be made in the future are outlined...... across the cell, effectively applying a square wave voltage with amplitude equal to the DC voltage to be measured. The switching circuit is based around two high voltage transistors TA, TB, with the Pockels cell electrodes being each connected to one of the transistor collectors. The transistor...

  5. A DC-Link Voltage Self-Balance Method for a Diode-Clamped Modular Multilevel Converter With Minimum Number of Voltage Sensors

    DEFF Research Database (Denmark)

    Gao, Congzhe; Jiang, Xinjian; Li, Yongdong

    2013-01-01

    Voltage balance issue of dc-link capacitors is very important for applications of a cascade multilevel converter or a modular multilevel converter. In this paper, a novel diode-clamped modular multilevel converter (DCM2C) topology is proposed and a power feedback control method is developed...

  6. Power flow analysis for DC voltage droop controlled DC microgrids

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Dragicevic, Tomislav

    2014-01-01

    This paper proposes a new algorithm for power flow analysis in droop controlled DC microgrids. By considering the droop control in the power flow analysis for the DC microgrid, when compared with traditional methods, more accurate analysis results can be obtained. The algorithm verification...... is carried out by comparing the calculation results with detailed time domain simulation results. With the droop parameters as variables in the power flow analysis, their effects on power sharing and secondary voltage regulation can now be analytically studied, and specialized optimization in the upper level...... control can also be made accordingly. Case studies on power sharing and secondary voltage regulation are carried out using proposed power flow analysis....

  7. Transformerless DC-DC Converter Using Cockcroft-Walton Voltage Multiplier to Obtain High DC Voltage

    Directory of Open Access Journals (Sweden)

    Meghana G Naik,

    2014-11-01

    Full Text Available In the present scenario the use of transformer for high voltages in converter circuit reduces the overall operating efficiency due to leakage inductance and use of transformer also increases the operational cost. . Therefore the proposed system is implemented with transformer less DC-DC converter so as to obtain high DC voltage with the use of nine stage Cockcroft-Walton (CW voltage multiplier. The proposed converter operates in CCM (continuous conduction mode, so that the converter switch stress, the switching losses are reduced. The DC voltage at the input of the proposed model is low and is boosted up by boost inductor (Ls in DC-DC converter stage and performs inverter operation. The number of stages in CW-voltage multiplier circuit is applied with low input pulsating DC (AC Voltage voltage where it is getting converted to high DC output voltage. The proposed converter switches operates at two independent frequencies, modulating (fsm andalternating (fsc frequency. The fsm operates at higher frequency of the output while the fsc operates at lower frequency of the desired output voltage ripple and the output ripples can be adjusted by the switch Sc1 and Sc2. The regulation of the output voltage is achieved by controlling the Duty ratio.The simulation is carried over by the MATLABSIMULINK.

  8. DC-Voltage Fluctuation Elimination Through a DC-Capacitor Current Control for DFIG Converters Under Unbalanced Grid Voltage Conditions

    DEFF Research Database (Denmark)

    Liu, Changjin; Xu, Dehong; Zhu, Nan;

    2013-01-01

    Unbalanced grid voltage causes a large second-order harmonic current in the dc-link capacitors as well as dc-voltage fluctuation, which potentially will degrade the lifespan and reliability of the capacitors in voltage source converters. This paper proposes a novel dc-capacitor current control...... method for a grid-side converter (GSC) to eliminate the negative impact of unbalanced grid voltage on the dc-capacitors. In this method, a dc-capacitor current control loop, where a negative-sequence resonant controller is used to increase the loop gain, is added to the conventional GSC current control...... loop. The rejection capability to the unbalanced grid voltage and the stability of the proposed control system are discussed. The second-order harmonic current in the dc capacitor as well as dc-voltage fluctuation is very well eliminated. Hence, the dc capacitors will be more reliable under unbalanced...

  9. A Secondary Voltage Control Method for an AC/DC Coupled Transmission System Based on Model Predictive Control

    DEFF Research Database (Denmark)

    Xu, Fengda; Guo, Qinglai; Sun, Hongbin;

    2015-01-01

    to keep the voltage of the pilot bus tracking its set point considering the DC system’s transmission schedule change. The approach is inspired by model predictive control (MPC) to compensate for predictable voltage change affected by DC side transmission power flow and the potential capacitor switching...

  10. Programmable Voltage Regulating Method for 15 kV High Voltage DC Power Supply%15 kV高压直流电源的程控调压方法

    Institute of Scientific and Technical Information of China (English)

    肖剑锋; 陈新; 米彦

    2008-01-01

    In order to solve the disadvantages caused by mechanical slide rheostat that has big errors and low precision, a novel voltage regulation method for high voltage DC power supply was introduced. The key of this method were digital potentiometer MAXIM 5455 and linear photoelectric coupling LOC110, and application programs were compiled using Visual Basic which was graphical compiling language, furthermore the communication between exterior and computer was carried out by ICP7044D module, in consequence the output value of high voltage DC power supply could be regulated with computer. The measured results showed that this method could accurately, conveniently and rapidly regulate the output value of high voltage DC power supply.

  11. An Improved Droop Control Method for DC Microgrids Based on Low Bandwidth Communication with DC Bus Voltage Restoration and Enhanced Current Sharing Accuracy

    DEFF Research Database (Denmark)

    Lu, Xiaonan; Guerrero, Josep M.; Sun, Kai;

    2014-01-01

    resistance in a droop-controlled dc microgrid, since the output voltage of each converter cannot be exactly the same, the output current sharing accuracy is degraded. Second, the DC bus voltage deviation increases with the load due to the droop action. In this paper, in order to improve the performance......, and the LBC system is only used for changing the values of the dc voltage and current. Hence, a decentralized control scheme is accomplished. The simulation test based on Matlab/Simulink and the experimental validation based on a 2×2.2 kW prototype were implemented to demonstrate the proposed approach....

  12. High Efficiency Interleaved Active Clamped Dc-Dc Converter with Fuel Cell for High Voltage Applications

    Directory of Open Access Journals (Sweden)

    Sona P

    2014-02-01

    Full Text Available A high efficiency interleaved ZVS active clamped current fed dc-dc converter is proposed in this paper specially used for fuel cell applications. As the fuel cell output is very low we are in need of a step up dc-dc converter. Here a current fed dc-dc converter is used. Two current fed dc-dc converters are interleaved by connecting their inputs in parallel and outputs in series. With this proposed methodology input current ripples in the fuel cell stacks can be reduced and a regulated output voltage ripples can be obtained. The active clamping circuit used in this model absorbs the turn off voltage spikes hence low voltage devices with low on state resistance can be used.Voltage doubler circuits will give double the output voltage than normal with smaller transformer turns ratio and flexibility. The proposed method is simulated in MATLAB for verifying the accuracy of the proposed design.

  13. DC injection into low voltage AC networks

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report summarises the results of a study investigating the impact of levels of injected DC current injections on a low voltage AC distribution network systems in order to recommend acceptable limits of DC from microgeneration. Relevant literature is reviewed, and the impact of DC levels in distribution transformers, transformer modelling, and instrumental transformers are discussed. The impact of DC in residual current devices (RCD) and in domestic electricity watt hour meters is examined along with DC enhanced corrosion, corrosion failure, and the measurement of DC current injection. Sources of DC injection outlined include DC from computer power supplies, network faults, geomagnetic phenomena, lighting circuits/dimmers, and embedded generators.

  14. High performance dc-dc conversion with voltage multipliers

    Science.gov (United States)

    Harrigill, W. T.; Myers, I. T.

    1974-01-01

    The voltage multipliers using capacitors and diodes first developed by Cockcroft and Walton in 1932 were reexamined in terms of state of the art fast switching transistors and diodes, and high energy density capacitors. Because of component improvements, the voltage multiplier, used without a transformer, now appears superior in weight to systems now in use for dc-dc conversion. An experimental 100-watt 1000-volt dc-dc converter operating at 100 kHz was built, with a component weight of about 1 kg/kW. Calculated and measured values of output voltage and efficiency agreed within experimental error.

  15. A Decentralized Control Method for Distributed Generations in an Islanded DC Microgrid Considering Voltage Drop Compensation and Durable State of Charge

    Directory of Open Access Journals (Sweden)

    Chul-Sang Hwang

    2016-12-01

    Full Text Available This paper presents a decentralized control method for distributed generations (DGs in an islanded direct current (DC microgrid. In most typical DC microgrids, a decentralized control method is based on a voltage droop control method. However, the grid voltage differs from node to node due to line voltage drop, and hence the power sharing ratio among DGs cannot be matched with as desired value. Especially in an islanded DC microgrid including an energy storage system as a voltage source, it is difficult for DGs to maintain the charge state of the ESS in a decentralized way. To overcome this problem, state of charge (SOC-voltage droop control is applied to the ESS. By using the proposed droop method, the SOC information can be assigned to the grid voltage, and hence the other DGs are able to support the SOC in a decentralized way. For DGs to enhance the accuracy of the SOC estimation, voltage drop is compensated for based on forecasting data and line impedance data. The simulation is modeled and implemented using Power System Computer Aided Design/Electromagnetic Transients for DC (PSCAD/EMTDC, version 4.2, Winnipeg, Manitoba, Canada and the simulation results show that the capability to maintain SOC as well as the system voltage profile are improved by using the proposed method.

  16. Regulation of a lightweight high efficiency capacitator diode voltage multiplier dc-dc converter

    Science.gov (United States)

    Harrigill, W. T., Jr.; Myers, I. T.

    1976-01-01

    A method for the regulation of a capacitor diode voltage multiplier dc-dc converter has been developed which has only minor penalties in weight and efficiency. An auxiliary inductor is used, which only handles a fraction of the total power, to control the output voltage through a pulse width modulation method in a buck boost circuit.

  17. Regulation of a lightweight high efficiency capacitor diode voltage multiplier dc-dc converter

    Science.gov (United States)

    Harrigill, W. T., Jr.; Myers, I. T.

    1976-01-01

    A method for the regulation of a capacitor diode voltage multiplier dc-dc converter has been developed which has only minor penalties in weight and efficiency. An auxiliary inductor is used, which only handles a fraction of the total power, to control the output voltage through a pulse width modulation method in a buck boost circuit.

  18. Voltage Tracking of a DC-DC Flyback Converter Using Neural Network Control

    Directory of Open Access Journals (Sweden)

    Wahyu Mulyo Utomo

    2012-01-01

    Full Text Available This paper proposes a neural network control scheme of a DC-DC Flyback converter that will step up a 12V DC and applied it on brushless DC motor with 12 and 24V dc. In this technique, a back propagation learning algorithm is derived. The controller is designed to track the output voltage of the DC-DC converter and to improve performance of the Flyback converter during transient operations. Furthermore, to investigate the effectiveness of the proposed controller, some operations such as starting-up and reference voltage variations are verified. The numerical simulation results show that the proposed controller has a better performance compare to the conventional PI-Controller method.

  19. Voltage control of DC islanded microgrids

    DEFF Research Database (Denmark)

    Tucci, Michele; Riverso, Stefano; Quintero, Juan Carlos Vasquez

    2015-01-01

    We propose a new decentralized control scheme for DC Islanded microGrids (ImGs) composed by several Distributed Generation Units (DGUs) with a general interconnection topology. Each local controller regulates to a reference value the voltage of the Point of Common Coupling (PCC) of the correspond......We propose a new decentralized control scheme for DC Islanded microGrids (ImGs) composed by several Distributed Generation Units (DGUs) with a general interconnection topology. Each local controller regulates to a reference value the voltage of the Point of Common Coupling (PCC...

  20. Zero-voltage switching technique in dc/dc converters

    Science.gov (United States)

    Liu, Kwang-Hwa; Lee, Fred C. Y.

    1990-07-01

    A novel resonant switch operating under the principle of zero-voltage switching is presented. In contrast to the zero-current switching, this technique eliminates the switching loss and dv/dt noise due to the discharging of MOSFET junction capacitances and the reverse recovery of diodes, and enables the converters to operate at high frequencies. A dc analysis of the converter is carried out. The duality relationship between the zero-current switching technique and the zero-voltage switching technique is derived. The two techniques are compared using an example showing the duality between a current-mode quasi-resonant Buck converter and a voltage-mode quasi-resonant boost converter. A 5-MHz 50 V to 5 V flyback converter employing the zero-voltage switching technique has been implemented. The circuit contains the smallest number of components possible, and yet maintains high efficiency at high switching frequency.

  1. Determination of appropriate DC voltage for switched mode power supply (SMPS) loads

    Science.gov (United States)

    Setiawan, Eko Adhi; Setiawan, Aiman; Purnomo, Andri; Djamal, Muchlishah Hadi

    2017-03-01

    Nowadays, most of modern and efficient household electronic devices operated based on Switched Mode Power Supply (SMPS) technology which convert AC voltage from the grid to DC voltage. Based on theory and experiment, SMPS loads could be supplied by DC voltage. However, the DC voltage rating to energize electronic home appliances is not standardized yet. This paper proposed certain method to determine appropriate DC voltage, and investigated comparison of SMPS power consumption which is supplied from AC and DC voltage. To determine the appropriate DC voltage, lux value of several lamps which have same specification energized by using AC voltage and the results is using as reference. Then, the lamps were supplied by various DC voltage to obtain the trends of the lux value to the applied DC voltage. After that, by using the trends and the reference lux value, the appropriate DC voltage can be determined. Furthermore, the power consumption on home appliances such as mobile phone, laptop and personal computer by using AC voltage and the appropriate DC voltage were conducted. The results show that the total power consumption of AC system is higher than DC system. The total power (apparent power) consumed by the lamp, mobile phone and personal computer which operated in 220 VAC were 6.93 VA, 34.31 VA and 105.85 VA respectively. On the other hand, under 277 VDC the load consumption were 5.83 W, 19.11 W and 74.46 W respectively.

  2. A high voltage ratio and low ripple interleaved DC-DC converter for fuel cell applications.

    Science.gov (United States)

    Chang, Long-Yi; Chao, Kuei-Hsiang; Chang, Tsang-Chih

    2012-01-01

    This paper proposes a high voltage ratio and low ripple interleaved boost DC-DC converter, which can be used to reduce the output voltage ripple. This converter transfers the low DC voltage of fuel cell to high DC voltage in DC link. The structure of the converter is parallel with two voltage-doubler boost converters by interleaving their output voltages to reduce the voltage ripple ratio. Besides, it can lower the current stress for the switches and inductors in the system. First, the PSIM software was used to establish a proton exchange membrane fuel cell and a converter circuit model. The simulated and measured results of the fuel cell output characteristic curve are made to verify the correctness of the established simulation model. In addition, some experimental results are made to validate the effectiveness in improving output voltage ripple of the proposed high voltage ratio interleaved boost DC-DC converters.

  3. Analysis of DC output voltage ripple in an electromagnetic doubly salient brushless DC generator

    Institute of Scientific and Technical Information of China (English)

    WANG Li; YAN Yangguang; CAO Xiaoqing; MENG Xiaoli

    2007-01-01

    Considering the salient pole and high magnetic nonlinearity of the electromagnetic doubly salient (EMDS)DC generator,a 12/8 pole prototype EMDS generator is designed and calculated using a 2-D finite element method (FEM).The phenomenon is analyzed and that the phase voltage wave changes between 120°and 180°.The influence of the exciting current and armature reaction on the DC voltage ripple of the generator is discussed in detail.and the nonlinear rules are gained that DC voltage rippie changes accordingly.The theoretical analysis is verified by the simulation and expefimental results.The results are helpful for the optimal design of the generator and the optimal control of excitingwinding.We conelude mat the filter-capacitance of the rectifier can be designed.

  4. A Bidirectional Multi-Port DC-DC Converter Integrating Voltage Equalizer

    DEFF Research Database (Denmark)

    Chen, Jianfei; Hou, Shiying; Deng, Fujin

    2015-01-01

    with a uniform voltage level while eliminating the voltage imbalance. In addition, high step-down and step-up ratios with low component voltage stress can be achieved in the proposed converter. A bidirectional four-port dc-dc converter is presented to do theoretical analysis for the voltage equalization of three...

  5. Variable Rail Voltage Control of a Brushless DC (BLDC) Motor

    Science.gov (United States)

    2013-01-01

    Variable Rail Voltage Control of a Brushless DC (BLDC) Motor by Yuan Chen, Joseph Conroy, and William Nothwang ARL-TR-6308 January 2013...TR-6308 January 2013 Variable Rail Voltage Control of a Brushless DC (BLDC) Motor Yuan Chen, Joseph Conroy, and William Nothwang Sensors...DATES COVERED (From - To) 4. TITLE AND SUBTITLE Variable Rail Voltage Control of a Brushless DC (BLDC) Motor 5a. CONTRACT NUMBER 5b. GRANT

  6. Five-Level Active-Neutral-Point-Clamped DC/DC Converter for Medium-Voltage DC Grids

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Chen, Zhe

    2017-01-01

    effectively eliminate high voltage leaps caused by the dead time effect. In addition, a capacitor voltage control strategy is proposed for the 5L-ANPC dc/dc converter to ensure the balanced flying capacitor voltage and desired five-level voltage waveforms. Finally, simulation and experimental studies......This paper proposes a five-level active-neutralpoint- clamped (5L-ANPC) dc/dc converter for applications in medium voltage dc (MVDC) grids. A modulation strategy is proposed for the 5L-ANPC dc/dc converter to generate multilevel voltage waveforms, which can effectively reduce voltage change rate dv...... are conducted, and the results have verified the proposed converter and control strategies....

  7. Dynamic Performance of Grid Converters using Adaptive DC Voltage Control

    DEFF Research Database (Denmark)

    Trintis, Ionut; Sun, Bo; Guerrero, Josep M.;

    2014-01-01

    This paper investigates a controller that ensures minimum operating dc-link voltage of a back-to-back converter system. The dc-link voltage adapts its reference based on the system state, reference given by an outer loop to the dc-link voltage controller. The operating dc-link voltage should...... be kept as low as possible to increase the power conversion efficiency and increase the reliability of converters. The dynamic performance of the proposed controller is investigated by simulations and experiments....

  8. A Component-Reduced Zero-Voltage Switching Three-Level DC-DC Converter

    DEFF Research Database (Denmark)

    Qin, Zian; Pang, Ying; Wang, Huai;

    2016-01-01

    The basic Zero-Voltage Switching (ZVS) three-level DC-DC converter has one clamping capacitor to realize the ZVS of the switches, and two clamping diodes to clamp the voltage of the clamping capacitor. In order to reduce the reverse recovery loss of the diode as well as its cost, this paper...... proposes to remove one of the clamping diodes in basic ZVS three-level DC-DC converter. With less components, the proposed converter can still have a stable clamping capacitor voltage, which is clamped at half of the dc link voltage. Moreover, the ZVS performance will be influenced by removing the clamping...

  9. A New Control Method of a Resonant Switched-Capacitor Converter and the Application for Balancing of the Split DC Voltages in a Multilevel Inverter

    Science.gov (United States)

    Sano, Kenichiro; Fujita, Hideaki

    This paper proposes a new voltage-balancing circuit for the split dc voltages in a diode-clamped five-level inverter. The proposed circuit is based on a resonant switched-capacitor converter (RSCC), which consists of two half-bridge inverters, a resonant inductor and a resonant capacitor. A new phase-shift control of the RSCC is proposed to improve voltage balancing performance. Theoretical analysis reveals the rating of the RSCC and stored energy in the resonant inductor. Experimental results confirm the reduction of the inductor to one tenth in volume as compared to a conventional voltage-balancing circuit based on buck-boost topology. Moreover, the proposed phase-shift control has demonstrated that it is possible to eliminate the voltage deviation between the dc capacitors.

  10. A Survey on Voltage Boosting Techniques for Step-Up DC-DC Converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam Prasad; Gorji, Saman Asghari;

    2016-01-01

    Step-up dc-dc converters are used to boost the voltage level of the input to a higher output level. Despite of its features such as simplicity of implementation, the fundamental boost dc-dc converter has shortcomings such as low boost ability and low power density. With these limitations, researc...

  11. A Fixed-Frequency Bidirectional Resonant DC-DC Converter Suitable for Wide Voltage Gain Range

    DEFF Research Database (Denmark)

    Shen, Yanfeng; Wang, Huai; Al-Durra, Ahmed;

    2017-01-01

    This paper proposes a new bidirectional resonant dc-dc converter suitable for wide voltage gain range applications (e.g., energy storage systems). The proposed converter overcomes the narrow voltage gain range of conventional resonant DC-DC converters, and meanwhile achieves high efficiency...... and characteristics of the proposed converter are analyzed. Finally, a 1-kW converter prototype is built and the experimental results verify the theoretical analyses....

  12. Extra-High-Voltage DC-DC Boost Converters Topology with Simple Control Strategy

    Directory of Open Access Journals (Sweden)

    K. Rajambal

    2009-01-01

    Full Text Available This paper presents the topology of operating DC-DC buck converter in boost mode for extra-high-voltage applications. Traditional DC-DC boost converters are used in high-voltage applications, but they are not economical due to the limited output voltage, efficiency and they require two sensors with complex control algorithm. Moreover, due to the effect of parasitic elements the output voltage and power transfer efficiency of DC-DC converters are limited. These limitations are overcome by using the voltage lift technique, opens a good way to improve the performance characteristics of DC-DC converter. The technique is applied to DC-DC converter and a simplified control algorithm in this paper. The performance of the controller is studied for both line and load disturbances. These converters perform positive DC-DC voltage increasing conversion with high power density, high efficiency, low cost in simple structure, small ripples, and wide range of control. Simulation results along theoretical analysis are provided to verify its performance.

  13. Elimination of output voltage oscillations in DC-DC converter using PWM with PI controller

    Directory of Open Access Journals (Sweden)

    Sreenivasappa Veeranna Bhupasandra

    2010-01-01

    Full Text Available In this paper the SIMULINK model of a PWM controlled DC-DC converter is modeled using switching function concept to control the speed of the DC motor. The presence of the voltage oscillation cycles due to higher switching frequency in the DC-DC converter is identified. The effect of these oscillations on the output voltage of the converter, Armature current, Developed torque and Speed of the DC motor is analyzed. In order to minimize the oscillation cycles the PI controller is proposed in the PWM controller.

  14. Voltage source inverters for high power, variable-voltage DC power sources

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z. [Department of Engineering and Technology, De Montfort University, Queens Building, The Gateway, Leicester, LE1 9BH, (United Kingdom); Spooner, E. [School of Engineering, University of Durham, Science Laboratories, South Rd, Durham, DRI 3LE, (United Kingdom)

    2001-09-01

    The paper discusses the applications of voltage source inverter (VSI) based power electronic systems for interfacing variable-voltage DC sources to the grid. A variable-speed wind power conversion system is used for illustration, where the VSI-based interface needs to convert a variable DC voltage to a nearly constant AC voltage with high-quality power. The power control principles of VSI are described. Various system configurations and switching strategies are examined by analysis, simulation and experimental methods. It is shown that better utilisation of semiconductors and more flexible control may be achieved by using a separately controlled DC link, rather than a directly connected VSI that has to operate at a lower modulation ratio at higher power. In some cases, multipulse inverter structures may be preferred, despite higher component count, because of reduced switching losses, fault tolerance and the absence of filters. The solutions developed in the study could be applied at a different scale to other renewable energy sources, such as wave or solar photovoltaic devices. (Author)

  15. A Protection Circuit for DC-DC Converter with Voltage Doubler

    Directory of Open Access Journals (Sweden)

    D.Elangovan

    2012-12-01

    Full Text Available This paper proposes a method to obtain a protected voltage gain by employing a protection circuit for the voltage doubler or multiplier circuit in an isolated tyde DC-DC Converter. The entire set up consists of a phase shift converter with a protected bridge/voltage doubler rectifier on the output side. The operating frequency of the phase shift converter is 20-25kHz (depending on the requirement of the application which is high enough to improve the efficiency. Ferrite core transformer is used in place of ordinary air core transformer, which is small in size with number of turns of the transformer is reduced and the overall power density is increased. The doubler circuit consists of electrolytic capacitors, which are rated at 400V in order to comply with IEC65 requirements. This paper proposes an “electrolytic capacitor protection circuit”, which enables the voltage rating of the electrolytics to be reduced to 250V. This circuit results in cost savings of more than 50% in the price of the electrolytic filter capacitors. The circuits were simulated using PSPICE SOFTWARE and the following results were obtained. For an input voltage of 200V, an output of 200V and400V were obtained in bridge mode and doubler mode respectively.

  16. Stability of DC Voltage Droop Controllers in VSC HVDC Systems

    DEFF Research Database (Denmark)

    Thams, Florian; Suul, Jon Are; D’Arco, Salvatore;

    2015-01-01

    Future multi-terminal HVDC systems are expected to utilize dc voltage droop controllers and several control implementations have been proposed in literature. This paper first classifies possible dc droop implementations in a simple framework. Then, the small-signal stability of a VSC-based conver......Future multi-terminal HVDC systems are expected to utilize dc voltage droop controllers and several control implementations have been proposed in literature. This paper first classifies possible dc droop implementations in a simple framework. Then, the small-signal stability of a VSC...

  17. DC Voltage Droop Control Implementation in the AC/DC Power Flow Algorithm: Combinational Approach

    DEFF Research Database (Denmark)

    Akhter, F.; Macpherson, D.E.; Harrison, G.P.

    2015-01-01

    In this paper, a combinational AC/DC power flow approach is proposed for the solution of the combined AC/DC network. The unified power flow approach is extended to include DC voltage droop control. In the VSC based MTDC grids, DC droop control is regarded as more advantageous in terms...... of operational flexibility, as more than one VSC station controls the DC link voltage of the MTDC system. This model enables the study of the effects of DC droop control on the power flows of the combined AC/DC system for steady state studies after VSC station outages or transient conditions without needing...... to use its complete dynamic model. Further, the proposed approach can be extended to include multiple AC and DC grids for combined AC/DC power flow analysis. The algorithm is implemented by modifying the MATPOWER based MATACDC program and the results shows that the algorithm works efficiently....

  18. Active Power and DC-link Voltage Coordinative Control for Cascaded DC-AC Converter with Bidirectional Power Application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Chen, Zhe; Deng, Fujin;

    2015-01-01

    Two stage cascaded converters are widely used in DC/AC hybrid systems to achieve the bidirectional power transmission. The topology of dual active bridge cascaded with inverter (DABCI) is commonly used in this application. This paper proposes a coordinative control method for DABCI and it’s able...... to reduce the DC-link voltage fluctuation between the DAB and inverter, then reduce the stress on the switching devices, as well as improve the system dynamic performance. In the proposed control method, the DAB and inverter are coordinated to control the DC-link voltage and the power......, and this responsibility sharing control can effectively suppress the impact of the power variation on the DC-link voltage, without sacrificing stability. The proposed control method is also effective for DABCI in unidirectional power transmission. The effectiveness of the propose control has been validated by both...

  19. High Output Voltage Based Multiphase Step-Up DC-DC Converter Topology with Voltage Doubler Rectifiers

    Directory of Open Access Journals (Sweden)

    Liao Xiaozhong

    2013-02-01

    Full Text Available High Output Voltage Based Multiphase Step-Up DC-DC Converter topology with voltage doubler rectifiers is presented in this paper. High output voltage is obtained due to the series combination of voltage doubler rectifiers on the secondary side of high frequency transformers. This topology is useful in the application where the output voltage is greater than the input. The two loop control strategy has been developed in order to analyze the stable and effective working of the converter topology. Therefore the working mode analysis of the converter topology has been described in detail. The multiphase step-up DC-DC converter topology is first simulated on MATLAB and then a prototype has been designed in order to verify the simulation and experimental results. Finally the simulation and experimental results are found to be satisfactory.

  20. Characterization of diode valve in medium voltage dc/dc converter for wind turbines

    DEFF Research Database (Denmark)

    Dincan, Catalin Gabriel; Kjær, Philip Carne

    2016-01-01

    This paper proposes a methodology for characterization of medium voltage (MV), medium frequency (MF) rectifier diode valve. The intended application is for 10MW dc/dc converters used in DC offshore wind turbines. Sensitivity to semiconductor component parameter variation, snubber component...

  1. Performance Characteristics of an Armature Voltage Controlled D.C. ...

    African Journals Online (AJOL)

    Performance Characteristics of an Armature Voltage Controlled D.C. Motor. ... the performance characteristics of a test motor are obtained by digital computer analysis. ... speed regulation and response characteristics for the d. c. drive system.

  2. A model based DC analysis of SiPM breakdown voltages

    CERN Document Server

    Nagy, Ferenc; Kalinka, Gabor; Molnar, Jozsef

    2016-01-01

    A new method to determine the breakdown voltage of SiPMs is presented. It is backed up by a DC model which describes the breakdown phenomenon by distinct avalanche turn-on ($V_{01}$) and turn off ($V_{10}$) voltages. It is shown that $V_{01}$ is related to the 'breakdown voltage' that previous DC methods derive from simple reverse current-voltage measurements, while $V_{10}$ is the 'real' breakdown voltage commonly obtained from complex gain-voltage measurements. The proposed method reveals how the microcell population distributes around $V_{01}$ and $V_{10}$. It is found that if this distribution is assumed to be normal, then both voltages and even their standard deviation can readily be extracted from current-voltage curves. Measurements are in good agreement with the theoretical model.

  3. An Optimal Control Strategy for DC Bus Voltage Regulation in Photovoltaic System with Battery Energy Storage

    Directory of Open Access Journals (Sweden)

    Muhamad Zalani Daud

    2014-01-01

    Full Text Available This paper presents an evaluation of an optimal DC bus voltage regulation strategy for grid-connected photovoltaic (PV system with battery energy storage (BES. The BES is connected to the PV system DC bus using a DC/DC buck-boost converter. The converter facilitates the BES power charge/discharge to compensate for the DC bus voltage deviation during severe disturbance conditions. In this way, the regulation of DC bus voltage of the PV/BES system can be enhanced as compared to the conventional regulation that is solely based on the voltage-sourced converter (VSC. For the grid side VSC (G-VSC, two control methods, namely, the voltage-mode and current-mode controls, are applied. For control parameter optimization, the simplex optimization technique is applied for the G-VSC voltage- and current-mode controls, including the BES DC/DC buck-boost converter controllers. A new set of optimized parameters are obtained for each of the power converters for comparison purposes. The PSCAD/EMTDC-based simulation case studies are presented to evaluate the performance of the proposed optimized control scheme in comparison to the conventional methods.

  4. An optimal control strategy for DC bus voltage regulation in photovoltaic system with battery energy storage.

    Science.gov (United States)

    Daud, Muhamad Zalani; Mohamed, Azah; Hannan, M A

    2014-01-01

    This paper presents an evaluation of an optimal DC bus voltage regulation strategy for grid-connected photovoltaic (PV) system with battery energy storage (BES). The BES is connected to the PV system DC bus using a DC/DC buck-boost converter. The converter facilitates the BES power charge/discharge to compensate for the DC bus voltage deviation during severe disturbance conditions. In this way, the regulation of DC bus voltage of the PV/BES system can be enhanced as compared to the conventional regulation that is solely based on the voltage-sourced converter (VSC). For the grid side VSC (G-VSC), two control methods, namely, the voltage-mode and current-mode controls, are applied. For control parameter optimization, the simplex optimization technique is applied for the G-VSC voltage- and current-mode controls, including the BES DC/DC buck-boost converter controllers. A new set of optimized parameters are obtained for each of the power converters for comparison purposes. The PSCAD/EMTDC-based simulation case studies are presented to evaluate the performance of the proposed optimized control scheme in comparison to the conventional methods.

  5. High voltage dc-dc converter with dynamic voltage regulation and decoupling during load-generated arcs

    Science.gov (United States)

    Shimer, Daniel W.; Lange, Arnold C.

    1995-01-01

    A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules.

  6. Power Capability in Low Voltage DC Distribution Systems

    Directory of Open Access Journals (Sweden)

    C.O. Gecan

    2009-12-01

    Full Text Available Recent developments in power electronics components enable the use of power electronics in Low Voltage (LV networks. This development makes the model of a Low Voltage Direct Current (LVDC distribution system possible. The technical and economical benefits of this technology make possible the alternative hypothesis of using DC instead of AC distribution systems. Some aspects, such as increasing the capability of the existing lines, interconnecting distributed generation units and even supplying in DC some loads are creating additional requirements of using a LVDC distribution system. The paper presents some general considerations regarding cables used in a LVAC distribution system and different line reconfigurations witch enable the use of cobles in a LVDC distribution system. The reconfigurations are presented in respect of the DC network topologies: unipolar and bipolar. The central aim of this paper is to investigate capability of power transmission and to calculate the transmission distance for cables used in Low Voltage AC and DC distribution systems. Capability computation is considered in respect of two constrains imposed in the cables cross section selection: cable thermal limit and the maximum allowable voltage drop. Cable thermal limit is represented in calculations by the maximum rated current. The equations used to calculate the power capability are presented for single-phase and threephase AC networks and unipolar and bipolar DC networks. Based on these equations, comparisons between power capability of cables with different cross sections used in Low Voltage DC and AC distribution systems are realized and presented.

  7. A Circulating-Current Suppression Method for Parallel Connected Voltage Source Inverters (VSI) with Common DC and AC Buses

    DEFF Research Database (Denmark)

    Wei, Baoze; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    applications. The basic concept of the proposed circulating-current suppression method is to modify the original current references by using the current difference among the parallel inverters. In the proposed approach, both of cross circulating-current and zero-sequence circulating-current are considered...... on the virtual impedance. Further, a circulating-current control loop is added to improve the average current-sharing performance among parallel VSIs. Experimental results are presented to show the effectiveness of the proposed control method to suppress both of the cross and zero-sequence circulating-currents....

  8. A Reduced-Part, Triple-Voltage DC-DC Converter for Electric Vehicle Power Management

    Energy Technology Data Exchange (ETDEWEB)

    Su, Gui-Jia [ORNL; Tang, Lixin [ORNL

    2007-01-01

    Electrical power systems in future hybrid and fuel cell vehicles may consist of three voltage nets; 14 V, 42 V and high voltage (>200 V) buses. A soft-switched, bi-directional dc-dc converter using only four switches was proposed for interconnecting the three nets. This paper presents a reduced- part dc-dc converter, which decreases the converter cost while retaining all the favorable features of the original topology. Simulation and experimental data are included to verify a simple power flow control scheme.

  9. High-Voltage DC-DC Converter Topology for PV Energy Utilization - Investigation and Implementation

    DEFF Research Database (Denmark)

    Sanjeevikumar, Padmanaban; Blaabjerg, Frede; Wheeler, Patrick

    2017-01-01

    This paper exploited the utilization of photovoltaic (PV) energy system with high-voltage (HV) output DC-DC converter. Classical boost converters are used for both renewable energy integration and HV applications, but limited by reducing output/efficiency in performance. Moreover, as parasitic...... elements suppress the power transfer ratio, converter needs to maximize the PV energy utilization. This investigation study focused to include additional parasitic elements (voltage-lift technique) to a standard DC-DC buck converter and to overcome all the above drawbacks to maximize the PV power...

  10. Analysis of high voltage step-up nonisolated DC-DC boost converters

    Science.gov (United States)

    Alisson Alencar Freitas, Antônio; Lessa Tofoli, Fernando; Junior, Edilson Mineiro Sá; Daher, Sergio; Antunes, Fernando Luiz Marcelo

    2016-05-01

    A high voltage step-up nonisolated DC-DC converter based on coupled inductors suitable to photovoltaic (PV) systems applications is proposed in this paper. Considering that numerous approaches exist to extend the voltage conversion ratio of DC-DC converters that do not use transformers, a detailed comparison is also presented among the proposed converter and other popular topologies such as the conventional boost converter and the quadratic boost converter. The qualitative analysis of the coupled-inductor-based topology is developed so that a design procedure can be obtained, from which an experimental prototype is implemented to validate the theoretical assumptions.

  11. High perfomance selectable value transportable high dc Voltage standard

    CERN Document Server

    Galliana, Flavio; Tet, Luca Roncaglione

    2016-01-01

    At National Institute of Metrological Research (INRIM), a selectable-value Transportable High dcVoltage Standard (THVS) operating in the range from 10 V to 100 V in steps of 10 V, was developed. This Standard was built to cover the lack of high level dc Voltage Standards at voltages higher than 10 V to employ as laboratory (local) or travelling Standards for Inter-Laboratory Comparisons (ILCs). A ground-mobile electronic technique was used to enhance the accuracy of the THVS at the higher values. The THVS shows better noise, better short-mid-term stability than top level dc Voltage and multifunction calibrators (MFCs) and better suitability and insensibility to be transported than these instruments. The project is extensible to 1000 V.

  12. A Circulating Current Suppression Method for Parallel Connected Voltage-Source-Inverters (VSI) with Common DC and AC Buses

    DEFF Research Database (Denmark)

    Wei, Baoze; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2016-01-01

    on circulating current control loops used to modify the reference currents by compensating the error currents among parallel inverters. Both of the cross and zero-sequence circulating currents are considered. The proposed method is coordinated together with droop and virtual impedance control. In this paper...... loop is added to acquire a better average current sharing performance among parallel VSIs, which can effectively suppress both of the cross and zero-sequence circulating currents. Experimental results are presented in order to verify the effectiveness of the proposed control strategy....

  13. Low-voltage limiters at DC railways; Niederspannungsbegrenzer fuer Gleichstrombahnen

    Energy Technology Data Exchange (ETDEWEB)

    Thiede, J. [Balfour Beatty Rail GmbH, Power Systems, Offenbach (Germany); Zeller, P. [Fachhochschul-Sudiengaenge Wels (Austria)

    2002-10-01

    Because the effects of stray currents direct earthing of running rails is undesirable at DC railways. Open links between return conductors and electrically conductive bodies are formed by low-voltage limiters, their application fields being derived from principal rules of return conducting at DC railways and further demands. A suitable technical solution is given by hybrid integrated circuitries. (orig.) [German] Bei DC-Bahnen ist die direkte Bahnerdung der Fahrschienen unerwuenscht wegen der Streustromgefahr. Niederspannungsbegrenzer bilden offene Verbindungen zwischen Rueckleitung und elektrisch leitfaehigen Koerpern. Ihre Einsatzbereiche leiten sich aus den Grundsaetzen der Rueckstromfuehrung bei DC-Bahnen und weiteren Anforderungen ab Eine technische Loesung hierfuer sind Hybridschaltungen. (orig.)

  14. Voltage Regulator for a dc-to-dc Converter

    Science.gov (United States)

    Mclyman, C. W.

    1983-01-01

    New voltage regulator isolates signals from power-switching converter without use of complex circuitry or optical couplers. Only addition is extra secondary winding on existing interstage transformer. Error signals shortcircuit new winding and inhibit converter action. Resistor in series with primary winding limits short-circuit current to prevent damage to circuit components. Extra transformer winding eliminates need for isolation components.

  15. A Four-Phase High Voltage Conversion Ratio Bidirectional DC-DC Converter for Battery Applications

    Directory of Open Access Journals (Sweden)

    Li-Kun Xue

    2015-06-01

    Full Text Available This study presents a four-phase interleaved high voltage conversion ratio bidirectional DC-DC converter circuit based on coupled inductors and switched capacitors, which can eliminate the defects of conventional high voltage conversion ratio bidirectional DC-DC converters in terms of high-voltage/current stress, less efficiency and low-power limitation. Parallel channels are used to reduce current stress at the low-voltage side and series connected switched capacitors are used to enlarge voltage conversion ratio, reduce voltage stress and achieve auto current sharing. This paper proposes the operation principle, feature analysis and optimization design considerations. On this basis the objectives of high voltage conversion ratio, low voltage/current stress, high power density, high efficiency and high-power applications can be achieved. Some experimental results based on a 500 W prototype converter (24 V to 48 V at low-voltage side, 400 V at high-voltage side are given to verify the theoretical analysis and the effectiveness of the proposed converter.

  16. Stability analysis and dynamic response of a DC-link module with a series voltage compensator

    DEFF Research Database (Denmark)

    Wang, Huai; Liu, Wenchao; Chung, Henry

    2013-01-01

    A DC-link module composed of a reduced value of DC-link capacitor and a series voltage compensator has been proposed. The voltage compensator processes the ripple voltage on the DC link and reactive power only, which can be implemented by low-voltage devices. The overall energy storage of the DC...

  17. Techniques for detecting proximity to voltage collapse in AC/DC systems

    Energy Technology Data Exchange (ETDEWEB)

    Canizares, Claudio A. [Escuela Politecnica Nacional, Quito (Ecuador); Long, Willis F.; Alvarado, Fernando L.; DeMarco, CChristopher L. [Wisconsin Univ., Madison, WI (United States)

    1992-12-31

    This paper describes three different techniques to detect proximity to voltage collapse (saddle-node bifurcation) in AC/DC systems; namely, direct (point of collapse) methods, continuation methods, and transient energy function methods. These techniques are compared among them, and also against the voltage sensitivity factor method using a 173 bus ac/dc test system. Various operational conditions are considered for this test system, so that transfer capabilities between areas and the effects of HVDC links can be analysed from the point of view of voltage collapse. 24 refs., 7 figs.

  18. A Super Performance Bandgap Voltage Reference with Adjustable Output for DC-DC Converter

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper presents a super performance bandgap voltage reference for DC-DC converter with adjustable output. It generates a wide range of voltage reference ranging from sub- 1V to 1.221 7 V and has a low temperature coefficient of 2.3 × 10 - 5/K over the temperature variation using the current feedback and resistive subdivision. In addition, the power supply rejection ration of the proposed bandgap voltage reference is 78 dB. When supply voltage varies from 2.5 V to 6 V, output VREF is 1.221 685 ± 0.055 mV.

  19. Voltage Control Scheme with Distributed Generation and Grid Connected Converter in a DC Microgrid

    Directory of Open Access Journals (Sweden)

    Jong-Chan Choi

    2014-10-01

    Full Text Available Direct Current (DC microgrids are expected to become larger due to the rapid growth of DC energy sources and power loads. As the scale of the system expends, the importance of voltage control will be increased to operate power systems stably. Many studies have been performed on voltage control methods in a DC microgrid, but most of them focused only on a small scale microgrid, such as a building microgrid. Therefore, a new control method is needed for a middle or large scale DC microgrid. This paper analyzes voltage drop problems in a large DC microgrid and proposes a cooperative voltage control scheme with a distributed generator (DG and a grid connected converter (GCC. For the voltage control with DGs, their location and capacity should be considered for economic operation in the systems. Accordingly, an optimal DG allocation algorithm is proposed to minimize the capacity of a DG for voltage control in DC microgrids. The proposed methods are verified with typical load types by a simulation using MATLAB and PSCAD/EMTDC.

  20. High performance dc-dc conversion with voltage multipliers. [using transformerless capacitor diode circuit

    Science.gov (United States)

    Harrigill, W. T., Jr.; Myers, I. T.

    1974-01-01

    An experimental 100W 1000V dc-dc converter using a capacitor diode voltage multipler (CDVM) with a nominal frequency of 100 kHz is studied. A component weight of about 1 kg/kW was obtained. Design equations for current, output -ripple and -power, efficiency and output voltage are derived. Agreement between experimental results and calculations is fairly good except for ripple.

  1. AC Voltage Control of DC/DC Converters Based on Modular Multilevel Converters in Multi-Terminal High-Voltage Direct Current Transmission Systems

    Directory of Open Access Journals (Sweden)

    Rui Li

    2016-12-01

    Full Text Available The AC voltage control of a DC/DC converter based on the modular multilevel converter (MMC is considered under normal operation and during a local DC fault. By actively setting the AC voltage according to the two DC voltages of the DC/DC converter, the modulation index can be near unity, and the DC voltage is effectively utilized to output higher AC voltage. This significantly decreases submodule (SM capacitance and conduction losses of the DC/DC converter, yielding reduced capital cost, volume, and higher efficiency. Additionally, the AC voltage is limited in the controllable range of both the MMCs in the DC/DC converter; thus, over-modulation and uncontrolled currents are actively avoided. The AC voltage control of the DC/DC converter during local DC faults, i.e., standby operation, is also proposed, where only the MMC connected on the faulty cable is blocked, while the other MMC remains operational with zero AC voltage output. Thus, the capacitor voltages can be regulated at the rated value and the decrease of the SM capacitor voltages after the blocking of the DC/DC converter is avoided. Moreover, the fault can still be isolated as quickly as the conventional approach, where both MMCs are blocked and the DC/DC converter is not exposed to the risk of overcurrent. The proposed AC voltage control strategy is assessed in a three-terminal high-voltage direct current (HVDC system incorporating a DC/DC converter, and the simulation results confirm its feasibility.

  2. DC-DC converter with a wide load range and a wide input-voltage range

    NARCIS (Netherlands)

    Ting, Y.

    2015-01-01

    This thesis investigated the possibility of increasing the efficiency of a DC-DC converter over a wide load range and a wide input-voltage range based on the Single Active Bridge (SAB) topology with two approaches. The first approach involved making changes to the topology whereas the second made us

  3. A Novel Quasi-SEPIC High-Voltage Boost DC-DC Converter

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; N. Soltani, Mohsen; Mostaan, Ali

    2017-01-01

    This paper proposes a modified coupled-inductor SEPIC dc-dc converter for low power and high voltage gain applications such as for piezoelectric drive systems. The converter uses the same components as of SEPIC converter with an additional diode. Compared to conventional topologies with similar v...

  4. A high voltage gain quasi Z-source isolated DC/DC converter

    DEFF Research Database (Denmark)

    Siwakoti, Yam P.; Blaabjerg, Frede; Loh, Poh Chiang

    2014-01-01

    A compact quasi-Z-source DC/DC converter is presented with high voltage gain, isolated output, and improved efficiency. The improvements in size and performance were achieved by using a square wave inverter with only two output switches driving an isolating transformer in push-pull mode, followed...

  5. High Voltage Coil Current Sensor for DC-DC Converters Employing DDCC

    Directory of Open Access Journals (Sweden)

    M. Drinovsky

    2015-12-01

    Full Text Available Current sensor is an integral part of every switching converter. It is used for over-current protection, regulation and in case of multiphase converters for balancing. A new high voltage current sensor for coil-based current sensing in DC-DC converters is presented. The sensor employs DDCC with high voltage input stage and gain trimming. The circuit has been simulated and implemented in 0.35 um BCD technology as part of a multiphase DC-DC converter where its function has been verified. The circuit is able to sustain common mode voltage on the input up to 40 V, it occupies 0.387*0.345 mm2 and consumes 3.2 mW typically.

  6. High-voltage boost quasi-Z-source isolated DC/DC converter

    DEFF Research Database (Denmark)

    Siwakoti, Yam P.; Blaabjerg, Frede; Loh, Poh Chiang

    2014-01-01

    A high-voltage gain two-switch quasi-Z-source isolated DC/DC converter has been presented in this study. It consists of a quasi-Z-source network at its input, a push-pull square-wave inverter at its middle, and a voltage-doubler rectifier at its output. When coordinated appropriately, the new...... converter uses less switches, a smaller common duty cycle and less turns for the transformer when compared with existing topologies. Its size and weight are therefore smaller, whereas its efficiency is higher. It is therefore well-suited for applications, where a wide range of voltage gain is required like...

  7. A New Secondary Control Approach for Voltage Regulation in DC Microgrids

    DEFF Research Database (Denmark)

    Peyghami Akhuleh, Saeed; Mokhtari, Hossein; Davari, Pooya

    2016-01-01

    In this paper the effect of secondary controller on voltage regulation in dc Micro-Grids (MGs) is studied. Basically, centralized or decentralized secondary controller has been employed to regulate the voltage drop raised by the primary controller. However, in the case of high capacity MGs and long...... feeders with much voltage drop on the line resistances, the conventional methods may not guarantee the voltage regulation on the load busses. Therefore, in addition to compensate the voltage drop of the primary controller, it is necessary to regulate the voltage of critical loads. In this paper, a new...... voltage regulation strategy is proposed to regulate the voltage of MG by employing the average voltage of identified busses, which are determined by the proposed modal analysis. Numerical steady state analysis and preliminary simulation results validate effectiveness of the proposed scheme. Furthermore...

  8. A Novel DC-Link Voltages Balancing Control Method for Cascaded H-Bridge Rectifier%一种H桥级联型PWM整流器的直流母线电压平衡控制新方法

    Institute of Scientific and Technical Information of China (English)

    陶兴华; 李永东; 孙敏

    2011-01-01

    直流电压平衡是H桥级联型整流器(CHBR)控制的主要问题。针对此本文提出了一种电压平衡控制新方法。文中推导了整流器的调制比增量与输出电压之间的关系式。在此基础上,通过反馈的直流电压重新配置调制比,以调节各路直流电压,使之达到平衡。文中讨论了在算法实现中遇到的问题,并给出了解决措施,得到一种较好的控制算法。对所提的方法进行了仿真与实验研究。结果表明,该方法适用于多级级联的CHBR拓扑,能够实现对输入电流以及各级输出电压平衡的控制。%DC-link voltages balancing is very important for cascaded H-bridge rectifier(CHBR).A new control method for voltages balancing is proposed in this paper.The relationship between the modulation index increment and the output voltage error is deduced.Therefore the modulation indexes of the cells are rearranged according to the measured dc voltages and the DC voltages are regulated to be the same value.The implement method for the proposed strategy is discussed in detail and the final method is derived.Simulations and experiments were carried out with the presented method.All of them approve that the proposed method is effective for such cascaded topology.The good performance is achieved when the CHBR is operating on the different conditions.

  9. Performance and scalability of isolated DC-DC converter topologies in low voltage, high current applications

    Energy Technology Data Exchange (ETDEWEB)

    Vaisanen, V.

    2012-07-01

    Fuel cells are a promising alternative for clean and efficient energy production. A fuel cell is probably the most demanding of all distributed generation power sources. It resembles a solar cell in many ways, but sets strict limits to current ripple, common mode voltages and load variations. The typically low output voltage from the fuel cell stack needs to be boosted to a higher voltage level for grid interfacing. Due to the high electrical efficiency of the fuel cell, there is a need for high efficiency power converters, and in the case of low voltage, high current and galvanic isolation, the implementation of such converters is not a trivial task. This thesis presents galvanically isolated DC-DC converter topologies that have favorable characteristics for fuel cell usage and reviews the topologies from the viewpoint of electrical efficiency and cost efficiency. The focus is on evaluating the design issues when considering a single converter module having large current stresses. The dominating loss mechanism in low voltage, high current applications is conduction losses. In the case of MOSFETs, the conduction losses can be efficiently reduced by paralleling, but in the case of diodes, the effectiveness of paralleling depends strongly on the semiconductor material, diode parameters and output configuration. The transformer winding losses can be a major source of losses if the windings are not optimized according to the topology and the operating conditions. Transformer prototyping can be expensive and time consuming, and thus it is preferable to utilize various calculation methods during the design process in order to evaluate the performance of the transformer. This thesis reviews calculation methods for solid wire, litz wire and copper foil winding losses, and in order to evaluate the applicability of the methods, the calculations are compared against measurements and FEM simulations. By selecting a proper calculation method for each winding type, the winding

  10. Space charge accumulation in polymeric high voltage DC cable systems

    NARCIS (Netherlands)

    Bodega, R.

    2006-01-01

    One of the intrinsic properties of the polymeric high voltage (HV) direct current (DC) cable insulation is the accumulation of electrostatic charges. Accumulated charges distort the initial Laplacian distribution of the electric field, leading to a local field enhancement that may cause insulation d

  11. 基于电压下垂法的直流微电网混合储能系统控制策略%Control Strategy of Hybrid Energy Storage Systems in DC Microgrid Based on Voltage Droop Method

    Institute of Scientific and Technical Information of China (English)

    文波; 秦文萍; 韩肖清; 王鹏; 刘家赢

    2015-01-01

    Aiming at stabilizing the DC bus voltage and optimizing the working process of the batteries, this paper presents a control strategy of hybrid energy storage systems in DC microgrid based on voltage droop method. The control strategy makes use of the ultracapacitor compensating the high-frequency components of bus power according to the DC bus voltage, indirectly compensates low-frequency components of bus power through the energy supplement of the batteries on the ultracapacitor, and takes advantage of the unable mutation characteristics of ultracapacitor voltage to achieve the smooth control of battery current. The control system can automatically switch work mode according to the conditions of DC bus voltage, ultracapacitor voltage and the state of charge (SOC) of battery. The experiments show that the control strategy can automatically adjust the output of batteries and ultracapacitor, maintain light fluctuation of DC bus voltage around rating, effectively reduce the frequency of battery charging and discharging and extend its using life.%以稳定直流母线电压和优化蓄电池工作过程为目的,提出了一种基于电压下垂法的直流微电网混合储能控制策略。该控制策略根据直流母线电压信息,利用超级电容快速补偿母线功率缺额的高频部分;通过蓄电池对超级电容进行能量补充,间接补偿母线功率缺额的低频部分;利用超级电容电压不能突变的特点,实现对蓄电池电流的平滑控制。控制系统以直流母线电压、超级电容电压及蓄电池荷电状态为判断条件,自动切换工作模式。实验表明,该控制策略可自动调节蓄电池和超级电容出力,维持直流母线电压在额定值附近小范围波动,有效地减小了蓄电池充放电次数,延长其使用寿命。

  12. Impedance of goat eye lens at different DC voltages.

    Science.gov (United States)

    Kohli, K S; Rai, D V; Jindal, V K; Goyal, N

    1998-09-01

    A computer assisted AC impedance system is used to measure the DC voltage-current (V-I) characteristics and AC impedance of a goat eye lens using a two-probe Ag-AgCl electrode system. The measurement of the V-I characteristics shows that when a DC voltage from 0 mV to 30 mV is applied, the resultant current decreases from an initial value of 0.58 microA to 0.006 microA. However, when the voltage is increases beyond 30 mV, the current increases and reaches a value of 0.9 microA at 100 mV. The data on the frequency response (0.01-10 Hz) of the impedance of lens tissue show an inverse relationship with frequency. The effect of various DC voltages, namely 0, 30, 50, 100 and 200 mV, on the impedance of the eye lens is also investigated over a frequency range of 0.01-10 Hz. The measurement results for both V-I characteristics and AC impedance further suggest the presence of a 30 mV voltage compartment in the goat eye lens.

  13. Efficiency and weight of voltage multiplier type ultra lightweight dc-dc converters

    Science.gov (United States)

    Harrigill, W. T., Jr.; Myers, I. T.

    1975-01-01

    An analytical and experimental study was made of a capacitor-diode voltage multiplier without a transformer which offers the possibility of high efficiency with light weight. The dc-dc conversion efficiencies of about 94 percent were achieved at output powers of 150 watts at 1000 volts using 8x multiplication. A detailed identification of losses was made, including forward drop losses in component, switching losses, reverse junction capacitance charging losses, and charging losses in the main ladder capacitors.

  14. A DC-DC Converter with Wide Input Voltage Range for Fuel Cell and Supercapacitor Application

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael Andreas E.

    2009-01-01

    This paper proposes a novel phase-shift plus duty cycle controlled hybrid bi-directional DC-DC converter based on fuel cells and supercapacitors. The described converter employs two high frequency transformers to couple the half-bridge and full-bridge circuits together in the primary side...... and voltage doubler circuit in secondary side. Boost type converter can limit the output ripple current of the fuel cells; hybrid full-bridge structure can change operating modes according to the different input voltage; phase-shift with duty cycle control scheme is utilized to control the bidirectional power...

  15. High voltage conversion ratio, switched C & L cells, step-down DC-DC converter

    DEFF Research Database (Denmark)

    Pelan, Ovidiu; Muntean, Nicolae; Cornea, Octavian;

    2013-01-01

    The paper presents a high voltage conversion ratio DC-DC step-down topology obtained from a classical buck converter associated with an input switched-capacitor cell and an output switched-inductor cell. Analytical descriptions, the voltage and current limits of the main components are synthesized...... in a comparative form, related to the classical buck structure, in order to emphasis the advantages of the proposed converter. Digital simulations and experimental results obtained with a built prototype are compared. From the first evaluation, the proposed converter is expected to be effectively used at input...

  16. DC power flow control for radial offshore multi-terminal HVDC transmission system by considering steady-state DC voltage operation range

    DEFF Research Database (Denmark)

    Irnawan, Roni; Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2017-01-01

    of this MTDC system due to the inherited limit from point-to-point (PtP) configuration. An analytic method is proposed in order to estimate the steady-state DC voltage operational points of this MTDC system. The proposed method has been confirmed with a conventional DC power flow study result....

  17. Novel Step-Up DC/DC Converter with No Right Half Plane Zero and Reduced Switched Voltage Stress Characteristics

    DEFF Research Database (Denmark)

    Mostaan, Ali; Alizadeh, Ebrahim; Soltani, Mohsen

    2014-01-01

    Novel step-up DC/DC converter is introduced in this paper. This converter is realized with adding the switched capacitor voltage multiplier cell to the three switch step-down DC/DC converter that has been proposed in the literature. The proposed converter is analyzed in the steady state and the v...

  18. PI and Fuzzy Control Strategies for High Voltage Output DC-DC Boost Power Converter - Hardware Implementation and Analysis

    DEFF Research Database (Denmark)

    Padmanaban, Sanjeevi Kumar; Blaabjerg, Frede; Siano, Pierluigi

    2016-01-01

    converter with inbuilt voltage-lift technique and overcome the aforementioned deficiencies. Further, the control strategy is adapted based on proportional-integral (P-I) and fuzzy logic, closed-loop controller to regulate the outputs and ensure the performances. Complete hardware prototype of EHV converter......This paper presents the control strategies by Proportional-Integral (P-I) and Fuzzy Logic (FL) for a DC-DC boost power converter for high output voltage configuration. Standard DC-DC converters are traditionally used for high voltage direct current (HVDC) power transmission systems. But, lack its...... performances in terms of efficiency, reduced transfer gain and increased cost with sensor units. Moreover, the internal self-parasitic components reduce the output voltage and efficiency of classical high voltage converters (HVC). This investigation focused on extra high-voltage (EHV) DC-DC boost power...

  19. DC Grid’s Multi-Point-Voltage Integrated Control Method With Energy Balance Distribution%基于换流站能量均衡的直流电网多点电压综合控制方法

    Institute of Scientific and Technical Information of China (English)

    杨越; 张文亮; 汤广福; 庞辉; 韩丛达

    2016-01-01

    In DC grid, voltage can not only reflect the whole system’s stability, but also has relationship with the converts’ energy, so voltage control is the key point in grid control. This paper analyzed the station constraints and the system constraints seriously, and proposed the DC grid’s multi-point-voltage integrated control method with energy balance distribution. This method resolved the conflicts between station constraints and system constraints, in other words, this method can not only guarantee the nodes’ independence but also guarantee the control variables’ relevance. A five-terminal DC grid was modeled and built in PSCAD to verify the correctness and effectiveness of the multi-point-voltage control method, in the model, normal operation andN–1 fault were considered. The conclusions drawn in this paper can provide theory foundations for the future DC grids’ multi-point-voltage control.%直流电网中的电压大小不仅能够反映整个系统的稳定程度,还与各换流站间的能量分布密切相关,因此直流电网的控制主要在于系统直流电压的控制。该文在详细分析直流输电系统网络约束和换流站约束的基础上,提出了基于能量均衡分布的直流电网多点电压控制方法。该方法可有效解决多点电压控制系统中各换流站约束和网络约束不一致的问题,即该方法既可保证网络约束中各节点变量的独立性又可保证换流站约束中各控制变量的相关性。文中还以五端直流电网为例,在PSCAD中进行模型搭建和仿真计算,通过系统在正常运行和N–1 故障运行两种情况下的响应结果,证明文章所提理论的正确性与有效性。该文结论可为以后直流电网的多点电压控制提供理论依据。

  20. Design of interleaved multilayer rosen type piezoelectric transformer for high voltage dc/dc applications

    DEFF Research Database (Denmark)

    Rødgaard, Martin Schøler; Andersen, Thomas; Meyer, Kaspar Sinding

    2012-01-01

    Research and development within piezoelectric transformer (PT) based converters are rapidly increasing as the technology is maturing and starts to prove its capabilities. Especially for high voltage and high step-up applications, PT based converters have demonstrated good performance and DC....../AC converters are widely used commercially. The availability of PT based converters for DC/DC applications are very limited and are not that developed yet. I this paper an interleaved multi layer Rosen-type PT for high step-up and high output voltage is developed, for driving a 2.5kV dielectric electro active...... and obtain soft switching capabilities. This can be achieved by utilising an advantageous PT structure, which is the main advantage of the interleaved Rosen-type PT. Furthermore the design should be further optimised, in order to achieve soft switching capability. The goal of this paper is to develop a soft...

  1. Enhancement of Voltage Stability of DC Smart Grid During Islanded Mode by Load Shedding Scheme

    Science.gov (United States)

    Nassor, Thabit Salim; Senjyu, Tomonobu; Yona, Atsushi

    2015-10-01

    This paper presents the voltage stability of a DC smart grid based on renewable energy resources during grid connected and isolated modes. During the islanded mode the load shedding, based on the state of charge of the battery and distribution line voltage, was proposed for voltage stability and reservation of critical load power. The analyzed power system comprises a wind turbine, a photovoltaic generator, storage battery as controllable load, DC loads, and power converters. A fuzzy logic control strategy was applied for power consumption control of controllable loads and the grid-connected dual active bridge series resonant converters. The proposed DC Smart Grid operation has been verified by simulation using MATLAB® and PLECS® Blockset. The obtained results show the effectiveness of the proposed method.

  2. Attaching single carbon nanotube on tip's apex using dielectrophoresis of DC-pulse voltage

    Institute of Scientific and Technical Information of China (English)

    Hee-Jin JEONG; Yoong-Ho JUNG; Deug-Woo LEE

    2009-01-01

    Single carbon nanotubes (CNTs) are candidates for a number of electronics and sensing applications, provided that single CNTs can be separated from a bundle of CNTs in suspension. Dielectrophoresis has recently been demonstrated as one route for the extraction of desired CNTs. However, previous methods using dielectrophoresis have found it difficult to extract single nanotubes from bundles of CNTs in solution. Here, we show that this restriction can be overcome by using pulsed DC voltage of an electric field, instead of regular AC and DC voltages.

  3. A New Zero Voltage Switching Buck-Boost Type DC-DC Converter

    Directory of Open Access Journals (Sweden)

    Majid Delshad

    2010-03-01

    Full Text Available In this paper, a new zero voltage switching isolated buck-boost DC-DC converter with active clamp circuit is proposed. The active clamp circuit in this converter not only absorbs voltage spikes across the main switch but also provides soft switching conditions for all switches. All switches are PWM controlled which simplifies the control implementation. One of the main advantages of this converter is the that it operating can operate at high power levels while soft switching conditions exist in both buck and boost modes of converter operation. Since this converter can operate over a wide input voltage range, it can be employed in power factor correction. The experimental results obtained from a 150W prototype circuit operating at 100KHz are presented to confirm the integrity of the proposed circuit.

  4. SOFT-SWITCHED HIGH STEP-UP DC-DC CONVERTER WITH HIGH VOLTAGE GAIN

    Directory of Open Access Journals (Sweden)

    J.C. PAUL IMMANUEL

    2013-04-01

    Full Text Available This paper presents a new design of soft switched high step-up dc-dc converter with high voltage gain which is suitable for high power applications such as Uninterruptible Power System (UPS, Photo Voltaic system and hybrid electric vehicles. The emergence of this front-end converter is to improve the shape of active input current given to the system. This converter proposes Soft-Switching technique to achieve ZVS turn on of active switches and ZCS turn off of diodes using Lr - Cr resonance in the auxiliary circuit. Therefore reduces the switching losses. Comparatively the voltage conversion ratio of this converter is higher when compared with the ordinary boost converter. Hence the voltage gain of this converter is also higher. A simulation platform is created using MATLAB which illustrates the ZVS and ZCS operation of the switches and diodes. Open loop and closed loop controlled converter systems are modelled and simulated.

  5. A dual VCDL DLL based gate driver for zero-voltage-switching DC-DC converter

    Science.gov (United States)

    Xin, Tian; Xiangxin, Liu; Wenhong, Li

    2010-07-01

    This paper presents a dual voltage-controlled-delay-line (VCDL) delay-lock-loop (DLL) based gate driver for a zero-voltage-switching (ZVS) DC-DC converter. Using the delay difference of two VCDLs for the dead time control, the dual VCDL DLL is able to implement ZVS control with high accuracy while keeping good linearity performance of the DLL and low power consumption. The design is implemented in the CSM 2P4M 0.35 μm CMOS process. The measurement results indicate that an efficiency improvement of 2%-4% is achieved over the load current range from 100 to 600 mA at 4 MHz switching frequency with 3.3 V input and 1.3 V output voltage.

  6. A dual VCDL DLL based gate driver for zero-voltage-switching DC-DC converter

    Energy Technology Data Exchange (ETDEWEB)

    Tian Xin; Liu Xiangxin; Li Wenhong, E-mail: wenhongli@fudan.edu.c [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)

    2010-07-15

    This paper presents a dual voltage-controlled-delay-line (VCDL) delay-lock-loop (DLL) based gate driver for a zero-voltage-switching (ZVS) DC-DC converter. Using the delay difference of two VCDLs for the dead time control, the dual VCDL DLL is able to implement ZVS control with high accuracy while keeping good linearity performance of the DLL and low power consumption. The design is implemented in the CSM 2P4M 0.35 {mu}m CMOS process. The measurement results indicate that an efficiency improvement of 2%-4% is achieved over the load current range from 100 to 600 mA at 4 MHz switching frequency with 3.3 V input and 1.3 V output voltage.

  7. SSP Technology Investigation of a High-Voltage DC-DC Converter

    Science.gov (United States)

    Pappas, J. A.; Grady, W. M.; George, Patrick J. (Technical Monitor)

    2002-01-01

    The goal of this project was to establish the feasibility of a high-voltage DC-DC converter based on a rod-array triggered vacuum switch (RATVS) for the Space Solar Power system. The RATVS has many advantages over silicon and silicon-carbide devices. The RATVS is attractive for this application because it is a high-voltage device that has already been demonstrated at currents in excess of the requirement for an SSP device and at much higher per-device voltages than existing or near-term solid state switching devices. The RATVS packs a much higher specific power rating than any solid-state device and it is likely to be more tolerant of its surroundings in space. In addition, pursuit of an RATVS-based system would provide NASA with a nearer-term and less expensive power converter option for the SSP.

  8. A High Voltage-lift Efficient Isolated Full Bridge DC-DC Converter

    Directory of Open Access Journals (Sweden)

    A. Gopi

    2014-05-01

    Full Text Available The aim of this study is to propose a high voltage lift isolated full bridge dc-dc converter. The proposed converter consists of an isolation transformer a low turn ratio to obtain high step up voltage gain. The secondary of the transformer connected with two boosting capacitors which connects parallel when power switches switch on period and discharged in series during the switch off period. In addition full bridge converter on primary side consists of clamping diode and capacitor, leakage energy is recycled there by improving conversion efficiency. The proposed circuits simulated using PSIM software form input voltage of 48V, an output of 410 V obtained. These results and operations experimented and validated by implementing in hardware model at 20/40 Vdc, 20 Watts.

  9. Fast response double series resonant high-voltage DC-DC converter

    Science.gov (United States)

    Lee, S. S.; Iqbal, S.; Kamarol, M.

    2012-10-01

    In this paper, a novel double series resonant high-voltage dc-dc converter with dual-mode pulse frequency modulation (PFM) control scheme is proposed. The proposed topology consists of two series resonant tanks and hence two resonant currents flow in each switching period. Moreover, it consists of two high-voltage transformer with the leakage inductances are absorbed as resonant inductor in the series resonant tanks. The secondary output of both transformers are rectified and mixed before supplying to load. In the resonant mode operation, the series resonant tanks are energized alternately by controlling two Insulated Gate Bipolar Transistor (IGBT) switches with pulse frequency modulation (PFM). This topology operates in discontinuous conduction mode (DCM) with all IGBT switches operating in zero current switching (ZCS) condition and hence no switching loss occurs. To achieve fast rise in output voltage, a dual-mode PFM control during start-up of the converter is proposed. In this operation, the inverter is started at a high switching frequency and as the output voltage reaches 90% of the target value, the switching frequency is reduced to a value which corresponds to the target output voltage. This can effectively reduce the rise time of the output voltage and prevent overshoot. Experimental results collected from a 100-W laboratory prototype are presented to verify the effectiveness of the proposed system.

  10. Model Based Optimization of Integrated Low Voltage DC-DC Converter for Energy Harvesting Applications

    Science.gov (United States)

    Jayaweera, H. M. P. C.; Muhtaroğlu, Ali

    2016-11-01

    A novel model based methodology is presented to determine optimal device parameters for the fully integrated ultra low voltage DC-DC converter for energy harvesting applications. The proposed model feasibly contributes to determine the maximum efficient number of charge pump stages to fulfill the voltage requirement of the energy harvester application. The proposed DC-DC converter based power consumption model enables the analytical derivation of the charge pump efficiency when utilized simultaneously with the known LC tank oscillator behavior under resonant conditions, and voltage step up characteristics of the cross-coupled charge pump topology. The verification of the model has been done using a circuit simulator. The optimized system through the established model achieves more than 40% maximum efficiency yielding 0.45 V output with single stage, 0.75 V output with two stages, and 0.9 V with three stages for 2.5 kΩ, 3.5 kΩ and 5 kΩ loads respectively using 0.2 V input.

  11. Performance of a Voltage Step-Up/Step-Down Transformerless DC/DC Converter: Analytical Model

    Science.gov (United States)

    Suskis, P.; Rankis, I.

    2012-01-01

    The authors present an analytical model for a voltage step-up/step-down DC/DC converter without transformers. The proposed topology is a combination of classic buck and boost converters in one single circuit but with differing operational principles. The converter is developed for a wind power autonomous supply system equipped with a hydrogen electrolytic tank and a fuel cell for energy stabilization. The main power source of the hydrogen-based autonomous supply system is energized by a synchronous generator operating on permanent magnets and equipped with a diode bridge. The input voltage of the converter in this case varies in the range 0-700 V, while its output DC voltage must be 540 V according to the demand of other parts of the system. To maintain the rated voltage, a special electrical load regulation is introduced. The calculations of the converter, the generator (equipped with a diode bridge) as element of the power system supply joint, and the load replaced by resistance are verified with PSIM software.

  12. An Improved Control Strategy of Limiting the DC-Link Voltage Fluctuation for a Doubly Fed Induction Wind Generator

    DEFF Research Database (Denmark)

    Yao, J.; Li, H.; Liao, Y.;

    2008-01-01

    The paper presents to develop a new control strategy of limiting the dc-link voltage fluctuation for a back-to-back pulsewidth modulation converter in a doubly fed induction generator (DFIG) for wind turbine systems. The reasons of dc-link voltage fluctuation are analyzed. An improved control...... strategy with the instantaneous rotor power feedback is proposed to limit the fluctuation range of the dc-link voltage. An experimental rig is set up to valid the proposed strategy, and the dynamic performances of the DFIG are compared with the traditional control method under a constant grid voltage....... Furthermore, the capabilities of keeping the dc-link voltage stable are also compared in the ride-through control of DFIG during a three-phase grid fault, by using a developed 2 MW DFIG wind power system model. Both the experimental and simulation results have shown that the proposed control strategy is more...

  13. Super-Twisting Differentiator-Based High Order Sliding Mode Voltage Control Design for DC-DC Buck Converters

    Directory of Open Access Journals (Sweden)

    Yigeng Huangfu

    2016-06-01

    Full Text Available This paper aims to focus on the smooth output of DC-DC buck converters in wireless power transfer systems under input perturbations and load disturbances using the high-order sliding mode controller (HOSM and HOSM with super-twisting differentiator (HOSM + STD. The proposed control approach needs only measurement of converter output voltage. Theoretical analysis and design procedures, as well as the super-twisting differentiator of the proposed controller are presented in detail with the prescribed convergence law of high-order sliding modes. Comparisons of both simulation and experimental results among conventional proportional-integral (PI control, traditional sliding mode control (SMC, HOSM and HOSM + STD under various test conditions such as steady state, input voltage perturbations and output load disturbances, are presented and discussed. The results demonstrate and validate the effectiveness and robustness of the proposed control method.

  14. A comprehensive analysis and hardware implementation of control strategies for high output voltage DC-DC boost power converter

    DEFF Research Database (Denmark)

    Padmanaban, Sanjeevikumar; Grandi, Gabriele; Blaabjerg, Frede

    2017-01-01

    Classical DC-DC converters used in high voltage direct current (HVDC) power transmission systems, lack in terms of efficiency, reduced transfer gain and increased cost with sensor (voltage/current) numbers. Besides, the internal self-parasitic behavior of the power components reduces the output v...

  15. State space analysis of boost DC/DC converter with voltage mode control

    Science.gov (United States)

    Shenoy, K. Latha; Nayak, C. Gurudas; Mandi, Rajashekar P.

    2017-07-01

    The boost converter belongs to the family of indirect energy transfer converters. The inductor stores energy during switch on and the output capacitor deliver power to the load. During switch off condition, the stored inductive energy appears in series with the input source and supply the output. The paper deals with the small signal analysis of dc-dc boost converter. It is used in modeling the closed loop converter parameters. The boost converter produces an undesirable Right-Half Plane Zero (RHPZ) in the small signal analysis due to which the implementation of voltage mode control needs attention. This requires compensating the regulator such that the crossover frequency occurs well below the frequency of the RHP zero. The paper describes modeling of voltage mode control boost converter operating in continuous conduction mode.

  16. A Simple MPPT Algorithm for Novel PV Power Generation System by High Output Voltage DC-DC Boost Converter

    DEFF Research Database (Denmark)

    Sanjeevikumar, Padmanaban; Grandi, Gabriele; Wheeler, Patrick

    2015-01-01

    This paper presents the novel topology of Photo Voltaic (PV) power generation system with simple Maximum Power Point Tracking (MPPT) algorithm in voltage operating mode. Power circuit consists of high output voltage DC-DC boost converter which maximizes the output of PV panel. Usually traditional...... of DC-DC converters for PV integration. Hence, to overcome these difficulties this paper investigates a DC-DC boost converter together with the additional parasitic component within the circuit to provide high output voltages for maximizing the PV power generation. The proposed power system circuit...... substantially improves the high output-voltage by a simple MPPT closed loop proportional-integral (P-I) controller, and requires only two sensor for feedback needs. The complete numerical model of the converter circuit along with PV MPPT algorithm is developed in numerical simulation (Matlab/Simulink) software...

  17. Electronic Current Transducer (ECT) for high voltage dc lines

    Science.gov (United States)

    Houston, J. M.; Peters, P. H., Jr.; Summerayes, H. R., Jr.; Carlson, G. J.; Itani, A. M.

    1980-02-01

    The development of a bipolar electronic current transducer (ECT) for measuring the current in a high voltage dc (HVDC) power line at line potential is discussed. The design and construction of a free standing ECT for use on a 400 kV line having a nominal line current of 2000 A is described. Line current is measured by a 0.0001 ohm shunt whose voltage output is sampled by a 14 bit digital data link. The high voltage interface between line and ground is traversed by optical fibers which carry digital light signals as far as 300 m to a control room where the digital signal is converted back to an analog representation of the shunt voltage. Two redundant electronic and optical data links are used in the prototype. Power to operate digital and optical electronics and temperature controlling heaters at the line is supplied by a resistively and capacitively graded 10 stage cascade of ferrite core transformers located inside the hollow, SF6 filled, porcelain support insulator. The cascade is driven by a silicon controlled rectifier inverter which supplies about 100 W of power at 30 kHz.

  18. A Multiphase, Modular, Bidirectional, Triple-Voltage DC-DC Converter Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    Su, Gui-Jia [ORNL; Tang, Lixin [ORNL

    2008-01-01

    Electrical power systems in future hybrid and fuel cell vehicles may employ three voltage [14 V, 42 V, and high voltage (HV)] nets. These will be necessary to accommodate existing 14-V loads as well as efficiently handle new heavy loads at the 42-V net and a traction drive on the HV bus. A low-cost DC-DC converter was proposed for connecting the three voltage nets. It minimizes the number of switches and their associated gate driver components by using two half-bridges and a high-frequency transformer. Another salient feature is that the half bridge on the 42-V bus is also utilized to provide the 14-V bus by operating at duty ratios around an atypical value of 1/3. Moreover, it makes use of the parasitic capacitance of the switches and the transformer leakage inductance for soft switching. The use of half bridges makes the topology well suited for interleaved multiphase modular configurations as a means to increase the power level because the capacitor legs can be shared. This paper presents simulation and experimental results on an interleaved two-phase arrangement rated at 4.5 kW. Also discussed are the benefits of operating with an atypical duty ratio on the transformer and a preferred multiphase configuration to minimize capacitor ripple currents.

  19. A Reduced-Part, Triple-Voltage DC-DC Converter for EV/HEV Power Management

    Energy Technology Data Exchange (ETDEWEB)

    Su, Gui-Jia [ORNL; Tang, Lixin [ORNL

    2009-01-01

    Electrical power systems in future hybrid and fuel cell vehicles may consist of three voltage nets: 14 V, 42 V, and high voltage (>200 V) buses. A soft-switched, bidirectional dc-dc converter that uses only four switches was proposed for interconnecting the three nets. This paper presents a reduced-part dc-dc converter, which decreases the converter cost while retaining all the favorable features of the original topology. Experimental data are included to verify a simple power flow control scheme.

  20. High-Voltage 1-kW dc/dc Converter Developed for Low-Temperature Operation

    Science.gov (United States)

    Patterson, Richard L.

    1998-01-01

    Recently, Lewis developed and demonstrated a high-voltage, 1-kW dc/dc converter that operates from room temperature to -184 C. A power supply designed for use in a NASA ion beam propulsion system was utilized as a starting point for the design of a low- (wide-) temperature dc/dc converter. For safety, we decided to halve the output voltage and power level, so the converter was designed for an 80-Vdc input and a 550-Vdc output at 1 kW.

  1. Effect of DC voltage pulses on memristor behavior.

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Brian R.

    2013-10-01

    Current knowledge of memristor behavior is limited to a few physical models of which little comprehensive data collection has taken place. The purpose of this research is to collect data in search of exploitable memristor behavior by designing and implementing tests on a HP Labs Rev2 Memristor Test Board. The results are then graphed in their optimal format for conceptualizing behavioral patterns. This series of experiments has concluded the existence of an additional memristor state affecting the behavior of memristors when pulsed with positively polarized DC voltages. This effect has been observed across multiple memristors and data sets. The following pages outline the process that led to the hypothetical existence and eventual proof of this additional state of memristor behavior.

  2. Nonlinear control of voltage source converters in AC-DC power system.

    Science.gov (United States)

    Dash, P K; Nayak, N

    2014-07-01

    This paper presents the design of a robust nonlinear controller for a parallel AC-DC power system using a Lyapunov function-based sliding mode control (LYPSMC) strategy. The inputs for the proposed control scheme are the DC voltage and reactive power errors at the converter station and the active and reactive power errors at the inverter station of the voltage-source converter-based high voltage direct current transmission (VSC-HVDC) link. The stability and robust tracking of the system parameters are ensured by applying the Lyapunov direct method. Also the gains of the sliding mode control (SMC) are made adaptive using the stability conditions of the Lyapunov function. The proposed control strategy offers invariant stability to a class of systems having modeling uncertainties due to parameter changes and exogenous inputs. Comprehensive computer simulations are carried out to verify the proposed control scheme under several system disturbances like changes in short-circuit ratio, converter parametric changes, and faults on the converter and inverter buses for single generating system connected to the power grid in a single machine infinite-bus AC-DC network and also for a 3-machine two-area power system. Furthermore, a second order super twisting sliding mode control scheme has been presented in this paper that provides a higher degree of nonlinearity than the LYPSMC and damps faster the converter and inverter voltage and power oscillations.

  3. A voltage resonance-based single-ended online fault location algorithm for DC distribution networks

    Institute of Scientific and Technical Information of China (English)

    JIA Ke; LI Meng; BI TianShu; YANG QiXun

    2016-01-01

    A novel single-ended online fault location algorithm is investigated for DC distribution networks.The proposed algorithm calculates the fault distance based on the characteristics of the voltage resonance.The Prony's method is introduced to extract the characteristics.A novel method is proposed to solve the pseudo dual-root problem in the calculation process.The multiple data windows are adopted to enhance the robustness of the proposed algorithm.An index is proposed to evaluate the accuracy and validity of the results derived from the various data windows.The performances of the proposed algorithm in different fault scenarios were evaluated using the PSCAD/EMTDC simulations.The results show that the algorithm can locate the faults with transient resistance using the 1.6 ms data of the DC-side voltage after a fault inception and offers a good precision.

  4. DC-link Voltage Control to Compensate Voltage Deviation for PV–BESSs Integrated System in Low-Voltage (LV Networks

    Directory of Open Access Journals (Sweden)

    Lee Gyu-sub

    2016-01-01

    Full Text Available The exhaustion of fossil fuel and the greenhouse gas emission are one of the most significant energy and environmental issues, respectively. Photovoltaic (PV generators and battery energy storage systems (BESSs have been significantly increased for recent years. The BESSs are mainly used for smoothing active power fluctuation of the PV. In this paper, PV–BESSs integration of two DC/DC converters and one AC/DC converter is investigated and DC-link voltage control to compensate the AC voltage deviation is proposed for the PV‒BESS system in low-voltage (LV networks.

  5. Design and implementation of a bidirectional current-controlled voltage-regulated DC-DC switched-mode converter

    CSIR Research Space (South Africa)

    Coetzer, A

    2016-01-01

    Full Text Available The design and implementation of a bidirectional current-controlled voltage-regulated DC-DC converter is presented. The converter is required to connect a battery of electrochemical cells (the battery) to an asynchronous motor-drive unit via a...

  6. Static DC to DC Power Conditioning-Active Ripple Filter, 1 MHZ DC to DC Conversion, and Nonlinear Analysis. Ph.D. Thesis; [voltage regulation and conversion circuitry for spacecraft power supplies

    Science.gov (United States)

    Sander, W. A., III

    1973-01-01

    Dc to dc static power conditioning systems on unmanned spacecraft have as their inputs highly fluctuating dc voltages which they condition to regulated dc voltages. These input voltages may be less than or greater than the desired regulated voltages. The design of two circuits which address specific problems in the design of these power conditioning systems and a nonlinear analysis of one of the circuits are discussed. The first circuit design is for a nondissipative active ripple filter which uses an operational amplifier to amplify and cancel the sensed ripple voltage. A dc to dc converter operating at a switching frequency of 1 MHz is the second circuit discussed. A nonlinear analysis of the type of dc to dc converter utilized in designing the 1 MHz converter is included.

  7. Five-Level Converter with Low Switching Frequency Applied as DC Voltage Supply

    DEFF Research Database (Denmark)

    Rasmussen, Tonny Wederberg

    1999-01-01

    This paper describes the use of a multi-level converter as a DC supply. Equations for the converter will be deduced in the nondissipative case. The equations provide solutions to DC voltage and the angle of converter voltage. In addition the spectrum for the harmonics after the elimination...

  8. A Voltage Quality Detection Method

    DEFF Research Database (Denmark)

    Chen, Zhe; Wei, Mu

    2008-01-01

    This paper presents a voltage quality detection method based on a phase-locked loop (PLL) technique. The technique can detect the voltage magnitude and phase angle of each individual phase under both normal and fault power system conditions. The proposed method has the potential to evaluate vario...... power quality disturbances, such as interruptions, sags and imbalances. Simulation studies have been performed. The effectiveness of the proposed method has been demonstrated under the simulated typical power disturbances....

  9. Voltage Scheduling Droop Control for State-of-Charge Balance of Distributed Energy Storage in DC Microgrids

    DEFF Research Database (Denmark)

    Li, Chendan; Dragicevic, Tomislav; Aldana, Nelson Leonardo Diaz

    2014-01-01

    the State-of-Charge balance. In this paper, a new droop method based on voltage scheduling for State-of-Charge balance is proposed to keep the SoC balance for the energy storage units. The proposed method has the advantage of avoiding the stability problem existed in traditional methods based on droop gain...... scheduling. Simulation experiment is taken in Matlab on a DC microgrid with two distributed energy storage units. The simulation results show that the proposed method has successfully achieved SoC balance during the load changes while maintaining the DC bus voltage within the allowable range....

  10. Distributed Control to Ensure Proportional Load Sharing and Improve Voltage Regulation in Low-Voltage DC Microgrids

    DEFF Research Database (Denmark)

    Anand, Sandeep; G. Fernandes, Baylon; Guerrero, Josep M.

    2013-01-01

    DC microgrids are gaining popularity due to high efficiency, high reliability, and easy interconnection of renewable sources as compared to the ac system. Control objectives of dc microgrid are: 1) to ensure equal load sharing (in per unit) among sources; and 2) to maintain low-voltage regulation...

  11. Improved DC-link Voltage Balancing Method for Cascaded H-bridge Rectifier%H桥级联型整流器直流电压平衡控制改进算法

    Institute of Scientific and Technical Information of China (English)

    陶兴华; 李永东; 宋义超; 石磊

    2012-01-01

    直流母线电压平衡控制是H桥级联型整流器(CHBR)主要的研究问题。为此在建立CHBR的数学模型基础上,分析了一种基于比例-积分(PI)调节器的CHBR直流电压平衡控制算法,并针对其不能空载运行的问题展开研究,利用相量图法揭示了该方法在空载时失控的内在机理;同时根据分析的结果提出了改进算法。改进算法的主要特点是通过使各功率单元的交流侧电压基波相位保持相同来实现空载条件下的电压控制,它不仅适用于直流电压给定值相同或者不相同的CHBR控制,同时也易于扩展到多单元的CHBR。对所提的算法进行了仿真研究,并搭建两单元CHBR的实验样机,对文中提到的改进算法进行了实验验证。实验结果表明了改进算法的有效性,同时也验证了改进算法和原算法在空载运行特性上的差异。%It is a challenge to balance the DC-link voltages of cascaded H-bridge rectifier(CHBR).We put forward an improved PI-based control method.Firstly,we establish a mathematics model of CHBR and introduce a PI-based DC-voltages balancing method.Then,we adopt the phasorial diagram method to discover and analyze the intrinsic reason that CHBR can not work on no-load condition with this control scheme.Based on the analysis results,measures are taken in control scheme to make the phases of all the cells' AC side voltage equal,which guarantees stability of system when the CHBR works on the no-load condition.The improved method can regulate the cell's voltages well,either the reference voltages are the same or different.Furthermore,it can easily extend to the CHBR with more cells,and is testified by a 4-cell CHBR simulation results.A 2-cell CHBR prototype is built in the laboratory.Accordingly,comparison experiments by the referred control method are done.The experimental results indicate the feasibility of the presented method and good performance on the no-load condition with

  12. DC-link voltage balancing in cascaded H-Bridge converters

    Directory of Open Access Journals (Sweden)

    Lewicki Arkadiusz

    2014-09-01

    Full Text Available In this paper a DC-link voltage balancing strategy for multilevel Cascaded H-Bridge (CHB converter is proposed. Presented solution bases on optimal choice of active vector durations in Space-Vector Pulse Width Modulation (SV-PWM. It makes it possible to DC-link voltages control and to properly generate the output voltage vector in the case of DC-link voltage unbalance. Results of simulation and experimental researches on proposed control strategy are presented in the paper

  13. Regular structures in 5CB liquid crystals under the joint action of ac and dc voltages

    Science.gov (United States)

    Aguirre, Luis E.; Anoardo, Esteban; Éber, Nándor; Buka, Ágnes

    2012-04-01

    A nematic liquid crystal with high, positive dielectric anisotropy (5CB) has been studied under the influence of the combined action of a dc and an ac electric field. Broad frequency, voltage, and cell thickness ranges were considered. Pattern morphologies were identified; the thresholds and critical wave numbers were measured and analyzed as a function of frequency, dc-to-ac voltage ratio, and thickness. The current-voltage characteristics were simultaneously detected.

  14. SVPWM Technique with Varying DC-Link Voltage for Common Mode Voltage Reduction in a Matrix Converter and Analytical Estimation of its Output Voltage Distortion

    Science.gov (United States)

    Padhee, Varsha

    Common Mode Voltage (CMV) in any power converter has been the major contributor to premature motor failures, bearing deterioration, shaft voltage build up and electromagnetic interference. Intelligent control methods like Space Vector Pulse Width Modulation (SVPWM) techniques provide immense potential and flexibility to reduce CMV, thereby targeting all the afore mentioned problems. Other solutions like passive filters, shielded cables and EMI filters add to the volume and cost metrics of the entire system. Smart SVPWM techniques therefore, come with a very important advantage of being an economical solution. This thesis discusses a modified space vector technique applied to an Indirect Matrix Converter (IMC) which results in the reduction of common mode voltages and other advanced features. The conventional indirect space vector pulse-width modulation (SVPWM) method of controlling matrix converters involves the usage of two adjacent active vectors and one zero vector for both rectifying and inverting stages of the converter. By suitable selection of space vectors, the rectifying stage of the matrix converter can generate different levels of virtual DC-link voltage. This capability can be exploited for operation of the converter in different ranges of modulation indices for varying machine speeds. This results in lower common mode voltage and improves the harmonic spectrum of the output voltage, without increasing the number of switching transitions as compared to conventional modulation. To summarize it can be said that the responsibility of formulating output voltages with a particular magnitude and frequency has been transferred solely to the rectifying stage of the IMC. Estimation of degree of distortion in the three phase output voltage is another facet discussed in this thesis. An understanding of the SVPWM technique and the switching sequence of the space vectors in detail gives the potential to estimate the RMS value of the switched output voltage of any

  15. Continuous-flow multi-pulse electroporation at low DC voltages by microfluidic flipping of the voltage space topology

    Science.gov (United States)

    Bhattacharjee, N.; Horowitz, L. F.; Folch, A.

    2016-10-01

    Concerns over biosafety, cost, and carrying capacity of viral vectors have accelerated research into physical techniques for gene delivery such as electroporation and mechanoporation. Advances in microfabrication have made it possible to create high electric fields over microscales, resulting in more efficient DNA delivery and higher cell viability. Continuous-flow microfluidic methods are typically more suitable for cellular therapies where a large number of cells need to be transfected under sterile conditions. However, the existing continuous-flow designs used to generate multiple pulses either require expensive peripherals such as high-voltage (>400 V) sources or function generators, or result in reduced cell viability due to the proximity of the cells to the electrodes. In this paper, we report a continuous-flow microfluidic device whose channel geometry reduces instrumentation demands and minimizes cellular toxicity. Our design can generate multiple pulses of high DC electric field strength using significantly lower voltages (15-60 V) than previous designs. The cells flow along a serpentine channel that repeatedly flips the cells between a cathode and an anode at high throughput. The cells must flow through a constriction each time they pass from an anode to a cathode, exposing them to high electric field strength for short durations of time (the "pulse-width"). A conductive biocompatible poly-aniline hydrogel network formed in situ is used to apply the DC voltage without bringing the metal electrodes close to the cells, further sheltering cells from the already low voltage electrodes. The device was used to electroporate multiple cell lines using electric field strengths between 700 and 800 V/cm with transfection efficiencies superior than previous flow-through designs.

  16. An atmospheric pressure plasma source driven by a train of monopolar high voltage pulses superimposed to a dc voltage

    OpenAIRE

    Stoican, O.S.

    2011-01-01

    Abstract An atmospheric pressure plasma source supplied by an electrical circuit consisting of two voltage sources in parallel connection is reported. One of them is a low-power self-oscillating flyback converter which produces negative voltage pulses with an amplitude of several kilovolts. The high voltage pulses are necessary to ignite an electrical discharge between the electrodes at atmospheric pressure. An additional dc source delivering several hundreds of volts at a few hund...

  17. Optical fiber sensor of partial discharges in High Voltage DC experiments

    Science.gov (United States)

    Búa-Núñez, I.; Azcárraga-Ramos, C. G.; Posada-Román, J. E.; Garcia-Souto, J. A.

    2014-05-01

    A setup simulating High Voltage DC (HVDC) transformers barriers was developed to demonstrate the effectiveness of an optical fiber (OF) sensor in detecting partial discharges (PD) under these peculiar conditions. Different PD detection techniques were compared: electrical methods, and acoustic methods. Standard piezoelectric sensors (R15i-AST) and the above mentioned OF sensors were used for acoustic detection. The OF sensor was able to detect PD acoustically with a sensitivity better than the other detection methods. The multichannel instrumentation system was tested in real HVDC conditions with the aim of analyzing the behavior of the insulation (mineral oil/pressboard).

  18. Optimal Design of DC to DC Boost Converter with Closed Loop Control PID Mechanism for High Voltage Photovoltaic Application

    Directory of Open Access Journals (Sweden)

    R. Arulmurugan

    2012-10-01

    Full Text Available This paper proposes a new dc to dc boost converter using closed loop control proportional Integral and Derivative mechanism for photovoltaic (PV standalone high voltage applications. The boost converter is composed of MOSFETs which are driven by closed loop PWM control. Many advantages including high efficiency, minimum number of switch, high voltage and power, low cost. This converter is attractive for high voltage and high power applications. The analysis and design considerations of the converter are presented. A prototype was implemented for an application requiring a 410W output power, input voltage range from 17.1-V, and a 317-V output voltage. The proposed system efficiency is about 90%.

  19. Optimal Design of DC to DC Boost Converter with Closed Loop Control PID Mechanism for High Voltage Photovoltaic Application

    Directory of Open Access Journals (Sweden)

    R. Arulmurugan

    2013-07-01

    Full Text Available This paper proposes a new dc to dc boost converter using closed loop control proportional Integral and Derivative mechanism for photovoltaic (PV standalone high voltage applications. The boost converter is composed of MOSFETs which are driven by closed loop PWM control. Many advantages including high efficiency, minimum number of switch, high voltage and power, low cost. This converter is attractive for high voltage and high power applications. The analysis and design considerations of the converter are presented. A prototype was implemented for an application requiring a 410W output power, input voltage range from 17.1-V, and a 317-V output voltage. The proposed system efficiency is about 90%.

  20. Four-Switch Three-Phase PMSM Converter with Output Voltage Balance and DC-Link Voltage Offset Suppression

    Directory of Open Access Journals (Sweden)

    Fadil Hicham

    2017-01-01

    Full Text Available High power quality, efficiency, complexity, size, cost effectiveness and switching losses of the direct current to alternating current (DC–AC conversion system are crucial aspects in industrial applications. Therefore, the four-switch three-phase inverter (4S3P has been proposed as an innovative inverter design. However, this topology has been known to have many performance limitations in the low-frequency region, because of the generation of an unbalanced voltage leading to an unbalanced current due to the fluctuation and offset of the centre tap voltage of the DC-link capacitors. Those drawbacks are investigated and solved in this paper in order to provide pure sinusoidal output voltages. The generated output voltages are controlled using proportional-integral (PI controllers to follow the desired voltages. Furthermore, the DC-link capacitor voltage offset is mitigated by subtracting the direct component from the control reference voltage using low pass filters, where this direct voltage component provides the direct current component which leads to DC-link capacitor voltage divergence. A simulation model and experimental setup are used to validate the proposed concept. Many simulation and experimental results are carried out to show the effectiveness of the proposed control scheme.

  1. Application of Multipoint DC Voltage Control in VSC-MTDC System

    Directory of Open Access Journals (Sweden)

    Yang Xi

    2013-01-01

    Full Text Available The voltage-source-converter- (VSC- based multiterminal VSC-HVDC power transmission system (VSC-MTDC is an ideal approach to connect wind farm with power grid. Analyzing the characteristics of doubly fed induction generators as well as the basic principle and the control strategy of VSC-MTDC, a multiterminal DC voltage control strategy suitable for wind farm connected with VSC-MTDC is proposed. By use of PSCAD/EMTDC, the proposed control strategy is simulated, and simulation results show that using the proposed control strategy the conversion between constant power control mode and constant DC voltage control mode can be automatically implemented; thus the DC voltage stability control and reliable power output of wind farm can be ensured after the fault-caused outage of converter station controlled by constant DC voltage and under other faults. The simulation result shows that the model can fulfill multiterminal power transmission and fast response control.

  2. Robust Frequency and Voltage Stability Control Strategy for Standalone AC/DC Hybrid Microgrid

    Directory of Open Access Journals (Sweden)

    Furqan Asghar

    2017-05-01

    Full Text Available The microgrid (MG concept is attracting considerable attention as a solution to energy deficiencies, especially in remote areas, but the intermittent nature of renewable sources and varying loads cause many control problems and thereby affect the quality of power within a microgrid operating in standalone mode. This might cause large frequency and voltage deviations in the system due to unpredictable output power fluctuations. Furthermore, without any main grid support, it is more complex to control and manage the system. In past, droop control and various other coordination control strategies have been presented to stabilize the microgrid frequency and voltages, but in order to utilize the available resources up to their maximum capacity in a positive way, new and robust control mechanisms are required. In this paper, a standalone microgrid is presented, which integrates renewable energy-based distributed generations and local loads. A fuzzy logic-based intelligent control technique is proposed to maintain the frequency and DC (direct current-link voltage stability for sudden changes in load or generation power. Also from a frequency control perspective, a battery energy storage system (BESS is suggested as a replacement for a synchronous generator to stabilize the nominal system frequency as a synchronous generator is unable to operate at its maximum efficiency while being controlled for stabilization purposes. Likewise, a super capacitor (SC and BESS is used to stabilize DC bus voltages even though maximum possible energy is being extracted from renewable generated sources using maximum power point tracking. This newly proposed control method proves to be effective by reducing transient time, minimizing the frequency deviations, maintaining voltages even though maximum power point tracking is working and preventing generators from exceeding their power ratings during disturbances. However, due to the BESS limited capacity, load switching

  3. Development of high voltage dc transmission at Siemens Schuckertwerke up to 1945

    Energy Technology Data Exchange (ETDEWEB)

    Bosch, M.; Schiele, O.

    1966-09-01

    High voltage dc affords advantages over three phase ac in the transmission of power over long distances and over cables, and in the coupling of three phase systems. Mercury arc rectifiers and equipment for dc voltages from 100 to 200 kV were developed and put into service in the period between 1937 and 1945. A few years ago a high voltage dc transmission group was formed by AEG, BBC and Siemens to continue the work interrupted at the end of the war.

  4. The Series Connected Buck Boost Regulator Concept for High Efficiency Light Weight DC Voltage Regulation

    Science.gov (United States)

    Birchenough, Arthur G.

    2003-01-01

    Improvements in the efficiency and size of DC-DC converters have resulted from advances in components, primarily semiconductors, and improved topologies. One topology, which has shown very high potential in limited applications, is the Series Connected Boost Unit (SCBU), wherein a small DC-DC converter output is connected in series with the input bus to provide an output voltage equal to or greater than the input voltage. Since the DC-DC converter switches only a fraction of the power throughput, the overall system efficiency is very high. But this technique is limited to applications where the output is always greater than the input. The Series Connected Buck Boost Regulator (SCBBR) concept extends partial power processing technique used in the SCBU to operation when the desired output voltage is higher or lower than the input voltage, and the implementation described can even operate as a conventional buck converter to operate at very low output to input voltage ratios. This paper describes the operation and performance of an SCBBR configured as a bus voltage regulator providing 50 percent voltage regulation range, bus switching, and overload limiting, operating above 98 percent efficiency. The technique does not provide input-output isolation.

  5. 电压反馈型半桥DC-DC变换器动力学特性%Dynamical Characteristic for Voltage-Feedback Half-Bridge DC-DC Converter

    Institute of Scientific and Technical Information of China (English)

    袁臣虎; 万健如; 李光叶; 周海亮

    2012-01-01

    Voltage-feedback half-bridge DC-DC converter, namely VCHB DC-DC, a dominant component of SMPS system, has rich dynamical characteristic. For revealing internal relation between system stability and circuit parameters, VCHB DC-DC converter was studied in detail. According to practical closed-loop control logic, the general simulation model was set up by using the exact state equations. And the general discrete mathematical model was deduced by stroboscopic maps. Nonlinearity characteristic of VCHB DC-DC converter under different parameters was simulated and analyzed by numerical method. Experimental results show that VCHB DC-DC converter is sensitive to transformer ratio, filter capacitor, inductive storage and error scale factor, while it is not sensitive to changes in error integral coefficient and load. The research results could serve as guidance for circuit parameters selection in VCHB DC-DC converter application.%电压反馈型半桥DC-DC (VCHB DC-DC)变换器组成的开关电源系统是强非线性系统,为揭示其系统稳定性与电路参数之间的内在关系,对VCHB DC-DC变换器进行了研究.结合其实际闭环控制逻辑,利用VCHB DC-DC变换器精确状态方程,建立VCHB DC-DC变换器仿真模型,采用频闪映射对其状态变量进行离散迭代映射,推导其统一的离散数学模型.对不同参数下VCHB DC-DC变换器非线性特性进行仿真和数值分析,并进行相应实验验证.研究结果表明,变压器变比、滤波电容、储能电感和误差比例系数的改变对VCHB DC-DC变换器稳定性影响大,而误差积分系数和负载的变化对其影响较弱.研究成果可为VCHB DC-DC变换器实际应用时的电路参数选取提供指导.

  6. Voltage Stability Bifurcation Analysis for AC/DC Systems with VSC-HVDC

    Directory of Open Access Journals (Sweden)

    Yanfang Wei

    2013-01-01

    Full Text Available A voltage stability bifurcation analysis approach for modeling AC/DC systems with VSC-HVDC is presented. The steady power model and control modes of VSC-HVDC are briefly presented firstly. Based on the steady model of VSC-HVDC, a new improved sequential iterative power flow algorithm is proposed. Then, by use of continuation power flow algorithm with the new sequential method, the voltage stability bifurcation of the system is discussed. The trace of the P-V curves and the computation of the saddle node bifurcation point of the system can be obtained. At last, the modified IEEE test systems are adopted to illustrate the effectiveness of the proposed method.

  7. Pull-in behavior analysis of vibrating functionally graded micro-cantilevers under suddenly DC voltage

    Directory of Open Access Journals (Sweden)

    Jamal Zare

    2015-01-01

    Full Text Available The present research attempts to explain dynamic pull-in instability of functionally graded micro-cantilevers actuated by step DC voltage while the fringing-field effect is taken into account in the vibrational equation of motion. By employing modern asymptotic approach namely Homotopy Perturbation Method with an auxiliary term, high-order frequency-amplitude relation is obtained, then the influences of material properties and actuation voltage on dynamic pull-in behavior are investigated. It is demonstrated that the auxiliary term in the homotopy perturbation method is extremely effective for higher order approximation and two terms in series expansions are sufficient to produce an acceptable solution. The strength of this analytical procedure is verified through comparison with numerical results.

  8. Loading Analysis of Modular Multi-level Converter for Offshore High-voltage DC Application under Various Grid Faults

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Loh, Poh Chiang;

    2016-01-01

    The modular multi-level converter has become an interesting candidate in high-voltage DC systems due to its higher voltage levels and modular construction. Low-voltage ride-through is an important grid requirement for modular multi-level converter–high-voltage DC since not only causes control cha...... be of importance for the design of the cooling system....

  9. Effects of DC bias voltages on the RF-excited plasma-tissue interaction

    Science.gov (United States)

    Yang, Aijun; Liu, Dingxin; Wang, Xiaohua; Li, Jiafeng; Chen, Chen; Rong, Mingzhe; Kong, Michael G.

    2016-10-01

    We present in this study how DC bias voltage impacts on the fluxes of reactive species on the skin tissue by means of a plasma-tissue interaction model. The DC bias voltage inputs less than 2% of the total discharge power, and hence it has little influence on the whole plasma characteritics including the volume-averaged densities of reactive species and the heating effect. However, it pushes the plasma bulk towards the skin surface, which significantly changes the local plasma characteristics in the vicinity of the skin surface, and in consequence remarkably enhances the flux densities of reactive species on the skin tissue. With the consideration of plasma dosage and heat damage on the skin tissue, DC bias voltage is a better approach compared with the common approach of increasing the plasma power. Since the DC voltage is easy to apply on the human body, it is a promising approach for use in clincial applications.

  10. Shaft Voltage and Life of Bearing electric-erosion for the Brushless DC Motor

    Science.gov (United States)

    Maetani, Tatsuo; Isomura, Yoshinori; Komiyama, Hiroshi; Morimoto, Shigeo

    This paper describes the life of noise of bearing electro-erosion in the shaft voltage of brushless DC motors. We confirmed that shaft voltage is suppressed to equal to or less than the dielectric breakdown voltage of bearing lubricant in the insulated rotor proposed for suppression of shaft voltage. However, since bearing electro-erosion appears over time along with the deterioration of noise performance, the threshold of the shaft voltage to secure noise performance over long periods of time is necessary. Therefore, the threshold of the shaft voltage that influences the life of noise was obtained in acceleration tests.

  11. New non-linear control strategy for non-isolated DC/DC converter with high voltage ratio

    Energy Technology Data Exchange (ETDEWEB)

    Shahin, A.; Huang, B.; Martin, J.P.; Pierfederici, S.; Davat, B. [Groupe de Recherche en Electronique et en Electrotechnique de Nancy - INPL - Nancy Universite, 2, Avenue de la Foret de Haye, 54516 Vandoeuvre-les-Nancy Cedex (France)

    2010-01-15

    In this paper, a non-isolated DC/DC converter with high voltage ratio is proposed to allow the interface between a low voltage power source like fuel cell and a high voltage DC bus. To take into account the low voltage-high density characteristics of power sources, a cascaded structure composed of two sub-converters has been chosen and allows obtaining a high voltage ratio. The choice of each sub-converter is based on the requirements of the source and its performances. Consequently, we have chosen a three-interleaved boost converter as the 1st sub-converter whereas the 2nd sub-converter is a three-level boost converter. The control of the whole system is realized thanks to energetic trajectories planning based on flatness properties of the system. The control of both the current and the balance of voltage across the output serial capacitors of the three-level boost converter is ensured by non-linear controllers based on a new non-linear model. Experimental results allow validating the proposed power architecture and its associated control. (author)

  12. Topologies Research of High Voltage and High Power DC/DC Converters Used in DC Grids%用于直流电网的高压大容量DC/DC变换器拓扑研究

    Institute of Scientific and Technical Information of China (English)

    魏晓光; 王新颖; 高冲; 张升

    2014-01-01

    随着世界范围内大力发展直流电网,作为直流电网中关键器件之一的高压大容量 DC/DC 变换器的研究尤为重要。针对目前关于DC/DC变换器研究主要集中于中低压小功率场合的现状,该文首先从多个角度对直流电网用的高压大容量DC/DC变换器进行了需求分析;其次,对现有文献中提出的适用于直流电网的 DC/DC 变换器拓扑进行了研究,并将输入端串联输出端串联(input-series output-series, ISOS)结构和低压 DC/DC 变换器相结合,提出了用于直流电网中输入端和输出端均为高电压场合的 ISOS 型 DC/DC变换器。比较分析了不同拓扑变换器的电压变比、开关器件的电气应力和故障处理能力等,为选择合适的高压大容量DC/DC变换器拓扑提供了依据。%ABSTRACT:As DC/DC converter is one of the most critical components in DC grids, the study of high voltage and high power DC/DC converter is increasingly important with the rapid development of DC grid all over the world. However, the study of DC/DC converter is mostly focused on low or middle voltage and low power applications. In this paper, the requirements of DC/DC Converters used in large DC grids are addressed firstly. And then possible DC/DC converter topologies are reviewed and input-series and output series DC/DC converter is proposed. Finally, in order to provide a basis for selecting suitable high voltage and high power converters in DC grids, the voltage stresses, voltage conversion ratios and fault management ability of different converters topologies are analyzed.

  13. A Half-Bridge Voltage Balancer with New Controller for Bipolar DC Distribution Systems

    Directory of Open Access Journals (Sweden)

    Byung-Moon Han

    2016-03-01

    Full Text Available This paper proposes a half-bridge voltage balancer with a new controller for bipolar DC distribution systems. The proposed control scheme consists of two cascaded Proportional Integral (PI controls rather than one PI control for balancing the pole voltage. In order to confirm the excellence of voltage balancing performance, a typical bipolar DC distribution system including a half-bridge voltage balancer with proposed controller was analyzed by computer simulations. Experiments with a scaled prototype were also carried out to confirm the simulation results. The half-bridge voltage balancer with proposed controller shows better performance than the half-bridge voltage balancer with one PI control for balancing the pole voltage.

  14. Usage of a dc-to-dc converter for voltage adaption between energy storage and propulsion system in electric or hybrid vehicles; Einsatz eines DC/DC-Wandlers zur Spannungsanpassung zwischen Antrieb und Energiespeicher in Elektro- und Hybridfahrzeugen

    Energy Technology Data Exchange (ETDEWEB)

    Schoenen, Timo

    2011-07-01

    Every time a new hybrid or electrical vehicle is developed, different topologies are compared to achieve the best results regarding weight costs and efficiency. The integration of a dc-to-dc converter between the battery stack and the power train is a frequently discussed alternative because the preferred voltage of the inverter and machine are often higher than the voltage of the battery stack. Within this thesis this approach was studied in detail and compared with the conventional concept without using a dc-to-dc converter. Therefore the influence of the dc-link voltage on the components like battery stack, machine, inverter and dc-to-dc converter was investigated. A change of the dc-link voltage leads to changes inside the components which affect weight, surface of the semiconductor devices and efficiency. This correlation could be used to develop a simulation process which optimizes the dc-link voltage regarding the programmed targets. In hybrid and electrical vehicles low weight and minimum costs are important and were defined as the main targets to achieve. The vantages which arise by using a dc-to-dc converter can be opposed to the disadvantages which also occur. The additional degree of freedom caused by the dc-to-dc converter shall be used. To achieve the best results regarding efficiency, the dc-link voltage has to be adapted to the operating point of the machine. First of all the dc-to-dc converter is an additional component with its weight, volume and losses. By the increased dc-link voltage on the drive train side, the size of the semiconductor devices inside the inverter could be reduced. Therefore the number of windings inside the machine has to be adapted accordingly. Also the wiring could be decreased based on the reduced currents. Overall there is still a higher weight and volume caused by the dc-to-dc converter. Also the efficiency map is influenced by the dc-to-dc converter. In the base speed region the dc-to-dc converter leads to a higher

  15. Development of modulation strategies for NPC converter addressing DC link voltage balancing and CMV reduction

    DEFF Research Database (Denmark)

    Boian, D.; Biris, C.; Teodorescu, Remus

    2012-01-01

    in insulation breakdown and bearing failures. By the use of this type of converters, both Electromagnetic Interference (EMI) and harmonic distortions are improved. This paper proposes two modulation strategies for Three Level Neutral Point Clamped Converter (3L-NPC). The main focus of these modulation...... strategies is to reduce the Common Mode Voltage (CMV) and balance the DC Link Voltage....

  16. ZVS Full-Bridge Based DC-DC Converter with Linear Voltage Gain According to Duty Cycle

    Science.gov (United States)

    Do, Hyun-Lark

    2013-09-01

    This paper presents a zero-voltage-switching (ZVS) full-bridge based DC-DC converter with linear voltage gain according to duty cycle. The proposed converter is based on an asymmetrical pulse-width-modulation (APWM) full-bridge converter which has various advantages over other converters. However, it has some drawbacks such as limited maximum duty cycle to 0.5 and narrow input range. The proposed converter overcomes these problems. The duty cycle is not limited and input voltage range is wide. Also, the ZVS operation of all power switches is achieved. Therefore, switching losses are significantly reduced and high-efficiency is obtained. Steady-state analysis and experimental results for the proposed converter are presented to validate the feasibility and the performance of the proposed converter.

  17. Optimal Constant DC Link Voltage Operation of aWave Energy Converter

    Directory of Open Access Journals (Sweden)

    Mats Leijon

    2013-04-01

    Full Text Available This article proposes a simple and reliable damping strategy for wave powerfarm operation of small-scale point-absorber converters. The strategy is based on passiverectification onto a constant DC-link, making it very suitable for grid integration of the farm.A complete model of the system has been developed in Matlab Simulink, and uses real sitedata as input. The optimal constant DC-voltage is evaluated as a function of the significantwave height and energy period of the waves. The total energy output of the WEC is derivedfor one year of experimental site data. The energy output is compared for two cases, onewhere the optimal DC-voltage is determined and held constant at half-hour basis throughoutthe year, and one where a selected value of the DC-voltage is kept constant throughout theyear regardless of sea state.

  18. Disturbance Attenuation of DC Voltage Droop Control Structures in a Multi-Terminal HVDC Grid

    DEFF Research Database (Denmark)

    Thams, Florian; Chatzivasileiadis, Spyros; Prieto-Araujo, Eduardo

    2017-01-01

    of the disturbance rejection of these droop control structures. The approach is based on multi-variable frequency response analysis where both ac and dc grid dynamics are incorporated. In particular, the amplification of dc voltage oscillations due to wind power variations is analyzed using singular value analysis......DC voltage droop control is seen as the preferred control structure for primary voltage control of future multiterminal HVDC systems. Different droop control structures have been proposed in literature which can be classified in eight categories. This paper contributes to an analysis....... Further, the impact of dc cable modeling on the results is discussed. In addition, it is shown that the maximum singular value limits, frequently used in literature for MIMO-analysis, are not sufficient to prove that the impact of certain disturbances on analyzed outputs is within a certain boundary...

  19. Modulation Voltage of High T c DC Superconducting Quantum Interference Device with Damping Resistance

    Science.gov (United States)

    Enpuku, Keiji; Doi, Hideki; Tokita, Go; Maruo, Taku

    1994-05-01

    The effect of damping resistance on the voltage versus flux (V -Φ) relation of the high T c dc superconducting quantum interference device (SQUID) is studied experimentally. Dc SQUID using YBaCuO step-edge junction and damping resistance in parallel with SQUID inductance is fabricated. Measured values of modulation voltage in the V -Φ relation are compared with those of the conventional SQUID without damping resistance. It is shown that modulation voltage is much improved by using damping resistance. The obtained experimental results agree reasonably with theoretical predictions reported previously.

  20. Stability Analysis of DC-link Voltage Control on Autonomous Micro Hydro Power Plant System

    Directory of Open Access Journals (Sweden)

    Feri Yusivar

    2014-12-01

    Full Text Available Micro Hydro Power Plant has become one of the interesting topics to be researched nowadays. This paper deals with the stability analysis on control system of excitation voltage in Micro Hydro Power Plant. The control of this voltage can be achieved by controlling the Permanent Magnet Synchronous Machine (PMSM with particular algorithm so the voltage on the DC-link part of the system can be controlled. Without knowing the exact specification of system parameters, the system will be most likely unstable. The DC-link control system is modeled, simulated, and mathematically analyzed so the parameter specification for the stable system can be obtained.

  1. Stability Analysis of DC-link Voltage Control on Autonomous Micro Hydro Power Plant System

    OpenAIRE

    Feri Yusivar; M. Shanizal; A. Subiantoro; Gunawan, R

    2014-01-01

    Micro Hydro Power Plant has become one of the interesting topics to be researched nowadays. This paper deals with the stability analysis on control system of excitation voltage in Micro Hydro Power Plant. The control of this voltage can be achieved by controlling the Permanent Magnet Synchronous Machine (PMSM) with particular algorithm so the voltage on the DC-link part of the system can be controlled. Without knowing the exact specification of system parameters, the system will be most likel...

  2. New zero voltage switching DC converter with flying capacitors

    Science.gov (United States)

    Lin, Bor-Ren; Shiau, Tung-Yuan

    2016-04-01

    A new soft switching converter is presented for medium power applications. Two full-bridge converters are connected in series at high voltage side in order to limit the voltage stress of power switches at Vin/2. Therefore, power metal-oxide-semiconductor field-effect transistors (MOSFETs) with 600 V voltage rating can be adopted for 1200 V input voltage applications. In order to balance two input split capacitor voltages in every switching cycle, two flying capacitors are connected on the AC side of two full-bridge converters. Phase-shift pulse-width modulation (PS-PWM) is adopted to regulate the output voltage. Based on the resonant behaviour by the output capacitance of MOSFETs and the resonant inductance, active MOSFETs can be turned on under zero voltage switching (ZVS) during the transition interval. Thus, the switching losses of power MOSFETs are reduced. Two full-bridge converters are used in the proposed circuit to share load current and reduce the current stress of passive and active components. The circuit analysis and design example of the prototype circuit are provided in detail and the performance of the proposed converter is verified by the experiments.

  3. Experimental validation of a high voltage pulse measurement method.

    Energy Technology Data Exchange (ETDEWEB)

    Cular, Stefan; Patel, Nishant Bhupendra; Branch, Darren W.

    2013-09-01

    This report describes X-cut lithium niobates (LiNbO3) utilization for voltage sensing by monitoring the acoustic wave propagation changes through LiNbO3 resulting from applied voltage. Direct current (DC), alternating current (AC) and pulsed voltage signals were applied to the crystal. Voltage induced shift in acoustic wave propagation time scaled quadratically for DC and AC voltages and linearly for pulsed voltages. The measured values ranged from 10 - 273 ps and 189 ps 2 ns for DC and non-DC voltages, respectively. Data suggests LiNbO3 has a frequency sensitive response to voltage. If voltage source error is eliminated through physical modeling from the uncertainty budget, the sensors U95 estimated combined uncertainty could decrease to ~0.025% for DC, AC, and pulsed voltage measurements.

  4. dc step response of induced-charge electro-osmosis between parallel electrodes at large voltages

    Science.gov (United States)

    Sugioka, Hideyuki

    2014-07-01

    Induced-charge electro-osmosis (ICEO) is important since it can be used for realizing high performance microfluidic devices. Here, we analyze the simplest problem of ion relaxation around a circular polarizable cylinder between parallel blocking electrodes in a closed cell by using a multiphysics coupled simulation technique. This technique is based on a combination of the finite-element method and finite-volume method for the Poisson-Nernst-Planck (PNP) equations having a flow term and the Stokes equation having an electric stress term. Through this analysis, we successfully demonstrate that on application of dc voltages, quadorapolar ICEO vortex flows grow during the charging time of the cylinder for both unbounded and bounded problems and decay during the charging time of the parallel electrodes only for the bounded problem using blocking electrodes. Further, by proposing a simple model that considers the two-dimensional (2D) PNP equations analytically, we successfully explain the step response time of the ICEO flow for the both unbounded and bounded problems. Furthermore, at low applied voltages, we find analytical formulations on steady diffused-ion problems and steady ICEO-flow problems and examine that our numerical results agree well with the analytical results. Moreover, by considering an ion-conserving condition with 2D Poisson-Boltzmann equations, we explain significant decrease of the maximum slip velocity at large applied voltages fairly well. We believe that our analysis will contribute greatly to the realistic designs of prospective high-performance microfluidic devices.

  5. SIMULATION ANALYSIS ON PROPORTIONAL INTEGRAL AND DERIVATIVE CONTROL OF CLOSED LOOP DC MOTOR DRIVE WITH BIPOLAR VOLTAGE SWITCHING

    Directory of Open Access Journals (Sweden)

    P. Karpagavalli

    2013-01-01

    Full Text Available This study presents the performance of a new four quadrant single phase DC drive closed loop system controlled by proportional integral and derivative controller with Pulse Width Modulation (PWM full bridge DC-DC converter using bipolar voltage switching. The proposed method is found to be more efficient in improving the step response characteristics such as reducing the settling time, rise time, steady state error and maximum overshoot in speed response of the closed loop DC motor drive and also reduced total harmonics distortion in the AC line current when compared to open loop system. The proposed topologies were simulated using MATLAB/Simulink software package and the results were obtained.

  6. Low start-up voltage dc–dc converter with negative voltage control for thermoelectric energy harvesting

    Directory of Open Access Journals (Sweden)

    Pui-Sun Lei

    2015-01-01

    Full Text Available This Letter presents a low start-up voltage dc–dc converter for low-power thermoelectric systems which uses a native n-type MOS transistor as the start-up switch. The start-up voltage of the proposed converter is 300 mV and the converter does not need batteries to start up. The negative voltage control is proposed to reduce the leakage current caused by native n-type transistor and increase the efficiency. The proposed converter was designed using standard 0.18 µm CMOS process with chip size of 0.388 mm^2. The peak efficiency is 63% at load current of 1.5 mA. The proposed converter provides output voltage >1 V at maximum load current of 3.2 mA.

  7. High-frequency high-voltage high-power DC-to-DC converters

    Science.gov (United States)

    Wilson, T. G.; Owen, H. A.; Wilson, P. M.

    1982-01-01

    A simple analysis of the current and voltage waveshapes associated with the power transistor and the power diode in an example current-or-voltage step-up (buck-boost) converter is presented. The purpose of the analysis is to provide an overview of the problems and design trade-offs which must be addressed as high-power high-voltage converters are operated at switching frequencies in the range of 100 kHz and beyond. Although the analysis focuses on the current-or-voltage step-up converter as the vehicle for discussion, the basic principles presented are applicable to other converter topologies as well.

  8. A Survey on Voltage Boosting Techniques for Step-Up DC-DC Converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam Prasad; Gorji, Saman Asghari;

    2016-01-01

    , researches on new voltage boosting techniques are inevitable for various power converter applications. This can be achieved either by additional magnetic or by electric field storage elements with switching elements (switch and/or diode) in different configurations. Such combination of primary voltage...... boosting techniques and topologies are large, which at times may be confusing and difficult to follow/adapt for different applications. Considering these aspects and in order to make a clear sketch of the general law and framework of various voltage boosting techniques, this paper comprehensively reviews...... different voltage boosting techniques and categorizes them according to their circuit performance....

  9. Neutral-point voltage control for a three-level DC-AC inverter using equivalent-input-disturbance approach

    Institute of Scientific and Technical Information of China (English)

    Jie ZHANG; Ryuichi YOKOYAMA; Jinhua SHE; Win WU

    2013-01-01

      One problem with a single source three-level inverter is the drafting of its neutral-point voltage. This may occur during transition or when unbalanced loads are connected to the inverter system. Variation of neutral-point voltage may greatly deteriorate the power quality. In this paper, we employ an equivalent-input-disturbance approach to deal with this problem. By adding an extra neutral leg, the control problem of neutral-point voltage is converted to a disturbance rejection problem. This method suppresses the variation of the neutral-point voltage to a low level and reduces the capacity of DC-link capacitors. Simulation results show the effectiveness of the method.

  10. Inductor based switching DC-DC converter for low voltage power distribution in SLHC

    CERN Document Server

    Michelis, S; Marchioro, A; Kayal, M; PH-EP

    2007-01-01

    In view of a power distribution scheme compatible with the requirements of the SLHC environment, we are evaluating the feasibility of on-board inductor-based DC-DC step-down conversion. Such converter should be an integrated circuit and capable of operating in harsh radiation environments and in the high magnetic field of the experiments. In this paper we present results concerning the choice of the technology, the search for the magnetic components and the calculations of the expected efficiency.

  11. Active power control with undead-band voltage & frequency droop applied to a meshed DC grid test system

    DEFF Research Database (Denmark)

    Vrana, Til Kristian; Zeni, Lorenzo; Fosso, Olav Bjarte

    2012-01-01

    A new method for controlling active power in HVDC grids has been tested on the meshed CIGRE B4 DC grid test system. The control strategy is based on the recently proposed undead-band droop control, which combines DC voltage and AC frequency droop. It provides sufficient roomm for optimisation...... for both normal and disturbed operation. Its main features are flexibility, reliability due to distributed control, easy expandability of the system and minimisation of communication needs. The control technique has been tested and its effectiveness has been verified to demonstrate its suitability...

  12. Push-pull with recovery stage high-voltage DC converter for PV solar generator

    Science.gov (United States)

    Nguyen, The Vinh; Aillerie, Michel; Petit, Pierre; Pham, Hong Thang; Vo, Thành Vinh

    2017-02-01

    A lot of systems are basically developed on DC-DC or DC-AC converters including electronic switches such as MOS or bipolar transistors. The limits of efficiency are quickly reached when high output voltages and high input currents are needed. This work presents a new high-efficiency-high-step-up based on push-pull DC-DC converter integrating recovery stages dedicated to smart HVDC distributed architecture in PV solar energy production systems. Appropriate duty cycle ratio assumes that the recovery stage work with parallel charge and discharge to achieve high step-up voltage gain. Besides, the voltage stress on the main switch is reduced with a passive clamp circuit and thus, low on-state resistance Rdson of the main switch can be adopted to reduce conduction losses. Thus, the efficiency of a basic DC-HVDC converter dedicated to renewable energy production can be further improved with such topology. A prototype converter is developed, and experimentally tested for validation.

  13. Design and power management of an offshore medium voltage DC microgrid realized through high voltage power electronics technologies and control

    Science.gov (United States)

    Grainger, Brandon Michael

    The growth in the electric power industry's portfolio of Direct Current (DC) based generation and loads have captured the attention of many leading research institutions. Opportunities for using DC based systems have been explored in electric ship design and have been a proven, reliable solution for transmitting bulk power onshore and offshore. To integrate many of the renewable resources into our existing AC grid, a number of power conversions through power electronics are required to condition the equipment for direct connection. Within the power conversion stages, there is always a requirement to convert to or from DC. The AC microgrid is a conceptual solution proposed for integrating various types of renewable generation resources. The fundamental microgrid requirements include the capability of operating in islanding mode and/or grid connected modes. The technical challenges associated with microgrids include (1) operation modes and transitions that comply with IEEE1547 without extensive custom engineering and (2) control architecture and communication. The Medium Voltage DC (MVDC) architecture, explored by the University of Pittsburgh, can be visualized as a special type of DC microgrid. This dissertation is multi-faceted, focused on many design aspects of an offshore DC microgrid. The focal points of the discussion are focused on optimized high power, high frequency magnetic material performance in electric machines, transformers, and DC/DC power converters---all components found within offshore, power system architectures. A new controller design based upon model reference control is proposed and shown to stabilize the electric motor drives (modeled as constant power loads), which serve as the largest power consuming entities in the microgrid. The design and simulation of a state-of-the-art multilevel converter for High Voltage DC (HVDC) is discussed and a component sensitivity analysis on fault current peaks is explored. A power management routine is

  14. Electron bunch structure in energy recovery linac with high-voltage dc photoelectron gun

    Science.gov (United States)

    Saveliev, Y. M.; Jackson, F.; Jones, J. K.; McKenzie, J. W.

    2016-09-01

    The internal structure of electron bunches generated in an injector line with a dc photoelectron gun is investigated. Experiments were conducted on the ALICE (accelerators and lasers in combined experiments) energy recovery linac at Daresbury Laboratory. At a relatively low dc gun voltage of 230 kV, the bunch normally consisted of two beamlets with different electron energies, as well as transverse and longitudinal characteristics. The beamlets are formed at the head and the tail of the bunch. At a higher gun voltage of 325 kV, the beam substructure is much less pronounced and could be observed only at nonoptimal injector settings. Experiments and computer simulations demonstrated that the bunch structure develops during the initial beam acceleration in the superconducting rf booster cavity and can be alleviated either by increasing the gun voltage to the highest possible level or by controlling the beam acceleration from the gun voltage in the first accelerating structure.

  15. Voltage ripple compensation for grid connected electrolyser power supply using small DC link capacitor

    DEFF Research Database (Denmark)

    Török, Lajos; Mathe, Laszlo; Munk-Nielsen, Stig

    2014-01-01

    The purpose of this work was to investigate a three-phase-grid connected power supply using small DC link capacitor for electrolyser application. The hydrogen generation system requires low voltage and high current power supply. Thus the structure of the 3-phase power supply is defined as follows......: a three phase rectification, a small DC-link capacitor and a phase-shifted full-bridge converter with current doubler rectification. Design constraints and control problems are investigated. The advantages and problems caused by the use of small DC link capacitor are presented. The control of the system...

  16. DC Voltage Control Strategy for CHB-STATCOM during Capacitive-Inductive Load Transition

    Directory of Open Access Journals (Sweden)

    Bo Zhao

    2012-11-01

    Full Text Available Fluctuation of DC capacitor voltage of CHC-STATCOM(Cascaded H-Bridge Converter Based STATCOM during capacitive-inductive load transition affects the dynamic response of the equipment and, with combination of other factors like of the switching devices, can degrade the stability of the equipment. This paper illustrates the cause ofthe voltage fluctuation and proposes a novel and practical control strategy to suppress it. A simulation was conducted to testify its effectiveness.

  17. Implementation of Inverter with Flexible Voltage Control for A DC Line in a System

    Directory of Open Access Journals (Sweden)

    M. Mohanraj

    2014-02-01

    Full Text Available Due to raising demands in electric power it becomes more important to use the available energy sources efficiently and along with them the distributed generation comes into picture which means collection of energy from many small sources say RES. For distribute generation (DG systems a challenging issue is to smartly integrate renewable-energy sources into the grid as it leads to power quality problems under fault conditions. Another approach for meeting the power demand is to implement TEP .This work proposes an method which uses a control algorithm for inverters for providing a flexible voltage control using reference current generation under grid faults. The controlled inverter designed is used for inversion processes at the receiving end in a HVDC line. A system with three sources is considered, their performances if the three lines connecting three sources are AC lines and if one line is replaced with a DC line is studied. Keywords –

  18. 基于储能设备的直流微电网母线电压控制策略研究%Control Strategy for DC Bus Voltage of DC Microgrid with Energy Storages

    Institute of Scientific and Technical Information of China (English)

    任琛; 刘志娟; 柳雪松

    2015-01-01

    In the DC microgrid with energy storages ,a system operation method and control strategy of DC bus voltage was proposed ,which takes DC bus voltage as control information and converters participating in the control of DC bus voltage .The DC microgrid is composed of one boost converter for PV arrays ,one DC/DC converter for battery charging/discharging ,one bidi‐rectional grid‐tied DC/AC converter and local loads .According to each unit operation features and system operation requirements ,the operations of system are categorized into four modes :iso‐lated with battery charging ,isolated with battery discharging ,grid‐connected with grid‐tied con‐verter inversion and grid‐connected with grid‐tied converter rectification .The operation modes and conversions are determined by the DC bus voltage .The control strategy can ensure that the DC microgrid is available of either grid‐connected mode or isolated mode ,realizing bus voltage stability and optimize energy utilization .The simulation and experiment results verify the effec‐tiveness of the proposed control strategy .%针对含储能设备的直流微电网系统,提出以直流母线电压为控制信号,各接口变换器分段参与母线电压调节的系统运行方法和母线电压控制策略。该控制策略能够保证直流微电网系统在孤岛、并网运行下稳定工作,实现母线电压恒定及能量最优利用。Simulink 仿真和 dSPACE实验验证该控制策略的有效性。

  19. Cascaded transformerless DC-DC voltage amplifier with optically isolated switching devices

    Science.gov (United States)

    Sridharan, Govind (Inventor)

    1993-01-01

    A very high voltage amplifier is provided in which plural cascaded banks of capacitors are switched by optically isolated control switches so as to be charged in parallel from the preceding stage or capacitor bank and to discharge in series to the succeeding stage or capacitor bank in alternating control cycles. The optically isolated control switches are controlled by a logic controller whose power supply is virtually immune to interference from the very high voltage output of the amplifier by the optical isolation provided by the switches, so that a very high voltage amplification ratio may be attained using many capacitor banks in cascade.

  20. Statistical Distributions of Partial Discharges in Oil-paper Insulation Under AC-DC Combined Voltages

    Institute of Scientific and Technical Information of China (English)

    LI Jian; JIANG Tianyan; HE Zhiman; CHENG Changkui; BAO Lianwei

    2012-01-01

    The converter transformer is one of the most critical equipments in high-voltage direct current transmission systems.Valve-side windings have to withstand complex stresses combined of AC,DC,and pulsed voltages.Partial discharges(PDs) can thus easily occur in oil-impregnated paper insulation.The current paper presents the statistical phase-resolved distributions of partial discharges in oil-paper insulation under combined AC and DC voltage stress.First,the voltages in the converter transformer were analyzed.In the experiments,four artificial insulation defect models were designed to generate PD signals under AC-DC combined voltage stress detected by a Rogowski coil sensor.Histograms including the φ-q-n data of these PD signals were created.The variations of φ-q-n data generated by PDs in different insulation defect models were analyzed while increasing the test voltage.Experimental results showed that the PD phase-resolved distributions of different insulation defect models were different from one another.The findings of the current study are useful in further research on the mechanism and pattern recognition of PDs in converter transformers.

  1. A New Secondary Control Approach for Voltage Regulation in DC Microgrids

    DEFF Research Database (Denmark)

    Peyghami Akhuleh, Saeed; Mokhtari, Hossein; Davari, Pooya;

    2016-01-01

    feeders with much voltage drop on the line resistances, the conventional methods may not guarantee the voltage regulation on the load busses. Therefore, in addition to compensate the voltage drop of the primary controller, it is necessary to regulate the voltage of critical loads. In this paper, a new...

  2. The Low Voltage LED Drivers with DC/DC Step Down Converters(I)%LED低压驱动电源——DC/DC降压变换器(上)

    Institute of Scientific and Technical Information of China (English)

    陈传虞

    2011-01-01

    The low voltage LED drivers with DC/DC between output voltage, input DC voltage, the formulas typical step down converter IC and its practical circuit step down converters are analyzed in detail. The relationship used to determine the circuit parameters%详细分析了DC/DC降压变换器驱动LED电路的工作原理,并推导了输出电压与输入电压的关系和电路参数选择依据的公式;给出一种DC/DC降压变换器芯片实例及其实用电路。

  3. Light weight, high power, high voltage dc/dc converter technologies

    Science.gov (United States)

    Kraus, Robert; Myers, Ira; Baumann, Eric

    1990-01-01

    Power-conditioning weight reductions by orders of magnitude will be required to enable the megawatt-power-level space systems envisioned by the Strategic Defense Initiative, the Air Force, and NASA. An interagency program has been initiated to develop an 0.1-kg/kW dc/dc converter technology base for these future space applications. Three contractors are in the first phase of a competitive program to develop a megawatt dc/dc converter. Researchers at NASA Lewis Research Center are investigating innovative converter topology control. Three different converter subsystems based on square wave, resonant, and super-resonant topologies are being designed. The components required for the converter designs cover a wide array of technologies. Two different switches, one semiconductor and the other gas, are under development. Issues related to thermal management and material reliability for inductors, transformers, and capacitors are being investigated in order to maximize power density. A brief description of each of the concepts proposed to meet the goals of this program is presented.

  4. DC-bus voltage control of grid-connected voltage source converter by using space vector modulated direct power control under unbalanced network conditions

    DEFF Research Database (Denmark)

    Xiao, Lei; Huang, Shoudao; Lu, Kaiyuan

    2013-01-01

    Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load. In this......Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load....... In this study, a new proportional-integral-resonant (PI-RES) controller-based, space vector modulated direct power control topology is proposed to suppress the dc-bus voltage ripple and in the same time, controlling effectively the instantaneous power of the VSC. A special ac reactive power reference component...

  5. AN ASSESSMENT OF HIGH-VOLTAGE DC ELECTRICAL POWER IN AIRCRAFT ELECTRICAL SYSTEMS.

    Science.gov (United States)

    If the presently installed three-phase ac transmission system on aircraft were replaced by a higher voltage dc ( HVDC ) transmission using a ground...from one- to two-thirds of the total electrical system weight. HVDC may have some disadvantages such as higher short-circuit currents, some increase in

  6. DC-link Voltage Coordinative-Proportional Control in Cascaded Converter Systems

    DEFF Research Database (Denmark)

    Tian, Yanjun; Loh, Poh Chiang; Deng, Fujin

    2015-01-01

    PI controllers are frequently implemented in cascaded converter system to control the DC-link voltage, because they can achieve zero steady state error. However the PI controller adds a pole at the origin point and a zero on the left half plane, and it increases the control system type number, an...

  7. A decentralized scalable approach to voltage control of DC islanded microgrids

    DEFF Research Database (Denmark)

    Tucci, Michele; Riverso, Stefano; Quintero, Juan Carlos Vasquez

    2016-01-01

    We propose a new decentralized control scheme for DC Islanded microGrids (ImGs) composed by several Distributed Generation Units (DGUs) with a general interconnection topology. Each local controller regulates to a reference value the voltage of the point of common coupling of the corresponding DGU...

  8. 高耐压重叠式反激DC-DC变换器设计%The Design of High Input-bus Voltage Flyback DC-DC Converters

    Institute of Scientific and Technical Information of China (English)

    赵伟光

    2001-01-01

    提出了一种高耐压重叠式反激DC-DC变换器拓扑,成功地解决了高输入母线电 压下低功率开关电源的设计问题。讨论了该拓扑的优点,给出了应用电路。%A topology of overlapping flyback DC-DC converter is proposed in this paper. By using this topology, the problem of designing the switched power converter in high input-bus voltage has been solved successfully. The advantages of this topology are discussed and some useful circuits are given as well.

  9. An on-die ultra-low voltage DC-DC step-up converter with voltage doubling LC-tank

    Science.gov (United States)

    Jayaweera, H. M. P. C.; Pathirana, W. P. M. R.; Muhtaroğlu, Ali

    2016-12-01

    In this paper we report the design, characterization and verification of a novel on-die ultra-low voltage DC-DC converter circuit for energy harvester applications in 0.18 µm complementary metal oxide semiconductor technology. The circuit self-starts, does not use off-chip components, and is thus suitable for use in highly integrated low cost systems. The first version of the design has a five-stage charge-pump stimulated by an oscillator with two center-tap inductors. It is validated on a test chip that this converter can boost 0.25 V-1.7 V for a 60 kΩ load with 15.5% maximum efficiency. The center-tap implementation leads to a 38% area reduction compared to the conventional four planar inductors. The proposed second version of the DC-DC design has a modified LC-tank with center-tap and planar hybrid inductors, which leads to a simulated step up from 0.2 V input to 1.65 V output for a 45 kΩ load with 35% maximum efficiency. The new boost implementation is hence expected to improve both power efficiency and output power capacity significantly compared to the first design, at a cost of a 31% layout area growth. The second revision in addition provides a 15% chip area reduction compared to the conventional four planar-inductor approach.

  10. Multi-Agent-Based Controller for Voltage Enhancement in AC/DC Hybrid Microgrid Using Energy Storages

    Directory of Open Access Journals (Sweden)

    Ahmadali Khatibzadeh

    2017-02-01

    Full Text Available Development of renewable energies and DC loads have led microgrids toward the creation of DC networks. The predictions show that the hybrid microgrids will be used widely in the future. This article has studied the voltage stability in the presence of sources of energy storage in AC/DC hybrid networks. However, because the different dynamics of hybrid networks applying centralized and distributed controllers will be faced with different problems, in this study, a multi-agent control for the microgrid has been used. A new structure referred to here as an event-driven microgrid control management (EDMCM has been developed to control the microgrid. This method increases response speed and accuracy of decision making. Hybrid Network Simulation results confirm the validity of the developed model.

  11. High frequency capacitor-diode voltage multiplier dc-dc converter development

    Science.gov (United States)

    Kisch, J. J.; Martinelli, R. M.

    1977-01-01

    A power conditioner was developed which used a capacitor diode voltage multiplier to provide a high voltage without the use of a step-up transformer. The power conditioner delivered 1200 Vdc at 100 watts and was operated from a 120 Vdc line. The efficiency was in excess of 90 percent. The component weight was 197 grams. A modified boost-add circuit was used for the regulation. A short circuit protection circuit was used which turns off the drive circuit upon a fault condition, and recovers within 5 ms after removal of the short. High energy density polysulfone capacitors and high speed diodes were used in the multiplier circuit.

  12. High-voltage testing of a 500-kV dc photocathode electron gun

    Science.gov (United States)

    Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki; Muto, Toshiya; Yamamoto, Masahiro; Honda, Yosuke; Miyajima, Tsukasa; Iijima, Hokuto; Kuriki, Masao; Kuwahara, Makoto; Okumi, Shoji; Nakanishi, Tsutomu

    2010-03-01

    A high-voltage dc photocathode electron gun was successfully conditioned up to a voltage of 550 kV and a long-time holding test for 8 h was demonstrated at an acceleration voltage of 500 kV. The dc photocathode electron gun is designed for future light sources based on energy-recovery linac and consists of a Cockcroft-Walton generator, a segmented cylindrical ceramic insulator, guard-ring electrodes, a support-rod electrode, a vacuum chamber, and a pressurized insulating gas tank. The segmented cylindrical ceramic insulator and the guard-ring electrodes were utilized to prevent any damage to the insulator from electrons emitted by the support-rod electrode.

  13. Enhanced DC-Link Capacitor Voltage Balancing Control of DC–AC Multilevel Multileg Converters

    DEFF Research Database (Denmark)

    Busquets-Monge, Sergio; Maheshwari, Ram Krishan; Nicolas-Apruzzese, Joan

    2015-01-01

    This paper presents a capacitor voltage balancing control applicable to any multilevel dc–ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc......-link voltage levels and converter legs (for single-phase and multiphase systems), guaranteeing the capacitor voltage control for any modulation index value and load (from idle mode to full power). The associated control loop small-signal transfer function is presented, from which optimum compensator design...... guidelines are derived. The improvement in control performance is verified through simulation and experiments comparing with a previous balancing control strategy in a four-level three-phase dc–ac conversion system. The satisfactory control performance is also verified through simulation in a four-level five...

  14. 超宽工作电压DC/DC变换器设计%Design of wide operating voltage DC/DC converter

    Institute of Scientific and Technical Information of China (English)

    王大为; 赵瑞杰; 陶学军; 田素立; 李朝锋

    2012-01-01

    Based on the situation of the wide output voltage range of solar photovoltaic power generation systems, a wide operating voltage of the DC / DC converter was designed. To solve the shortcoming of high voltage stress of the power when the switch was off, the voltage regulator tube was Introduced in order to clamp the voltage. To ensure the saturation switch conduction of the MOSFET, a rational circuit was designed to induce the current from the secondary circuit as the MOSFET gate driver. Based on the theoretical analysis, simulation and optimization, a 15 W, 1 000 V /200 V input prototype was designed.The test results show that the converter can work stably tor a long time.%针对太阳能光伏发电系统输出电压较宽的情况,设计了一种超宽工作电压的DC/DC变换器.利用稳压管在开关关断时对电路进行电压钳位,解决了单管反激变换器在高电压输入时电力MOSFET电压应力过高的缺陷.通过合理设计电路并从电路副边引入电流作为MOSFET栅极驱动,可以保证开关管的饱和导通.在理论分析、仿真优化、反复调试的基础上,设计了一款15W、1 000 V/200 V输入的样机.经过测试,此变换器可以长时间稳定工作且转换效率比较高.

  15. Voltage Balancing Method on Expert System for 51-Level MMC in High Voltage Direct Current Transmission

    Directory of Open Access Journals (Sweden)

    Yong Chen

    2016-01-01

    Full Text Available The Modular Multilevel Converters (MMC have been a spotlight for the high voltage and high power transmission systems. In the VSC-HVDC (High Voltage Direct Current based on Voltage Source Converter transmission system, the energy of DC link is stored in the distributed capacitors, and the difference of capacitors in parameters and charge rates causes capacitor voltage balance which affects the safety and stability of HVDC system. A method of MMC based on the expert system for reducing the frequency of the submodules (SMs of the IGBT switching frequency is proposed. Firstly, MMC with 51 levels for HVDC is designed. Secondly, the nearest level control (NLC for 51-level MMC is introduced. Thirdly, a modified capacitor voltage balancing method based on expert system for MMC-based HVDC transmission system is proposed. Finally, a simulation platform for 51-level Modular Multilevel Converter is constructed by using MATLAB/SIMULINK. The results indicate that the strategy proposed reduces the switching frequency on the premise of keeping submodule voltage basically identical, which greatly reduces the power losses for MMC-HVDC system.

  16. Advanced medium-voltage bidirectional dc-dc conversion systems for future electric energy delivery and management systems

    Science.gov (United States)

    Fan, Haifeng

    2011-12-01

    The distributed renewable energy generation and utilization are constantly growing, and are expected to be integrated with the conventional grid. The growing pressure for innovative solutions will demand power electronics to take an even larger role in future electric energy delivery and management systems, since power electronics are required for the conversion and control of electric energy by most dispersed generation systems Furthermore, power electronics systems can provide additional intelligent energy management, grid stability and power quality capabilities. Medium-voltage isolated dc-dc converter will become one of the key interfaces for grid components with moderate power ratings. To address the demand of medium voltage (MV) and high power capability for future electric energy delivery and management systems, the power electronics community and industry have been reacting in two different ways: developing semiconductor technology or directly connecting devices in series/parallel to reach higher nominal voltages and currents while maintaining conventional converter topologies; and by developing new converter topologies with traditional semiconductor technology, known as multilevel converters or modular converters. The modular approach uses the well-known, mature, and cheaper power semiconductor devices by adopting new converter topologies. The main advantages of the modular approach include: significant improvement in reliability by introducing desired level of redundancy; standardization of components leading to reduction in manufacturing cost and time; power systems can be easily reconfigured to support varying input-output specifications; and possibly higher efficiency and power density of the overall system. Input-series output-parallel (ISOP) modular configuration is a good choice to realize MV to low voltage (LV) conversion for utility application. However, challenges still remain. First of all, for the high-frequency MV utility application, the low

  17. Experimental Results of a DC Bus Voltage Level Control for a Load-Controlled Marine Current Energy Converter

    Directory of Open Access Journals (Sweden)

    Johan Forslund

    2015-05-01

    Full Text Available This paper investigates three load control methods for a  marine current energy converter using a vertical axis current  turbine (VACT mounted on a permanent magnet synchronous generator  (PMSG. The three cases are; a fixed AC load, a fixed pulse width  modulated (PWM DC load and DC bus voltage control of a DC  load. Experimental results show that the DC bus voltage control  reduces the variations of rotational speed by a factor of 3.5 at the cost  of slightly increased losses in the generator and transmission lines.  For all three cases, the tip speed ratio \\(\\lambda\\ can be kept close to  the expected \\(\\lambda_{opt}\\. The power coefficient is estimated to be  0.36 at \\(\\lambda_{opt}\\; however, for all three cases, the average  extracted power was about \\(\\sim 19\\\\%. A maximum power point  tracking (MPPT system, with or without water velocity measurement,  could increase the average extracted power.

  18. KEY COMPARISON: Report on key comparison EUROMET.EM-K8 (DC voltage ratio)

    Science.gov (United States)

    Marullo Reedtz, G.; Cerri, R.

    2004-01-01

    The purpose of the regional comparison EUROMET.EM-K8 was to compare the scaling capabilities up to 1000 V DC of the European national metrology institutes, thus extending to Europe the evaluation of equivalence of voltage ratio measurements obtained by the comparison CCEM-K8. Twenty laboratories participated, with the Istituto Elettrotecnico Nazionale Galileo Ferraris (Torino, Italy) acting as pilot laboratory. The circulation of the travelling standard, a resistive voltage divider, started in July 1998 and ended in January 2002. The technical protocol requested the measurement of voltage ratios 1000 V/10 V and 100 V/10 V, the measurement of other ratios being optional. Nineteen laboratories reported measurements of the mandatory ratios. For these ratios, the measurement methods used are described and the process to evaluate the comparison reference value and the degrees of equivalence is reported in detail. The relative uncertainty of the comparison, given by the combination of the uncertainty of the reference value and the instability of the transfer standard, was about 0.26×10-6 for ratio 1000 V/10 V and about 0.16×10-6 for ratio 100 V/10 V, at 95% level of confidence. The results for the optional ratios are reported in an appendix. With some exceptions, the agreement between the results is satisfactory. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the Mutual Recognition Arrangement (MRA).

  19. Long Lifetime DC-Link Voltage Stabilization Module for Smart Grid Application

    DEFF Research Database (Denmark)

    Wang, Huai; Chung, Henry; Liu, Wenchao

    2012-01-01

    Power converters enable efficient and flexible control and conversion of electric energy among different smart grid players (i.e. producers, energy storage systems, and loads). One of the expected features of smart grid is that it will be more reliable compared to conventional grid. However, power...... converters are one kind of the lifetime limiting components applied in smart grid. One of the major causes is the malfunction of electrolytic capacitors (E-Caps) which are widely used for stabilizing the dc-link voltage in various types of power converters applied in smart grid. A dc-link module is therefore...

  20. Design and Construction of Low Cost High Voltage dc Power Supply for Constant Power Operation

    Science.gov (United States)

    Kumar, N. S.; Jayasankar, V.

    2013-06-01

    Pulsed load applications like laser based systems need high voltage dc power supplies with better regulation characteristics. This paper presents the design, construction and testing of dc power supply with 1 kV output at 300 W power level. The designed converter has half bridge switched mode power supply (SMPS) configuration with 20 kHz switching. The paper covers the design of half bridge inverter, closed loop control, High frequency transformer and other related electronics. The designed power supply incorporates a low cost OPAMP based feedback controller which is designed using small signal modelling of the converter. The designed converter was constructed and found to work satisfactorily as per the specifications.

  1. FUNCTIONAL CORRELATION OF FP AND DC METHODS

    Directory of Open Access Journals (Sweden)

    Marin Kaluža

    2013-02-01

    Full Text Available Most of organizations today use information-communication technologies (ICT for building an information system (IS. IS is assembled of hardware, software, network resources, organizational and human resources. In IS development process, complexity is crucial for evaluating quantities of resources needed (time, people, money, equipment. Complexity of an IS can be evaluated and/or measured in different phases of development. There are many methods for measuring complexity, but mostly used and thoroughly described method is Function Point Analysis (FP. The opposite method, Database Complexity (DC, does not measure all the aspects of IS, but it could evaluate system complexity depending on the database complexity. DC method is intended to be used for measuring semantic complexity of the IS database, and can be shown by counting attributes A and foreign keys F. This paper describes a very high correlation between FP and DC methods, and defines a function which can in 95% of accuracy express FP values from measured DC values.

  2. A Bidirectional, Triple-Voltage DC-DC Converter for Hybrid and Fuel Cell Vehicle Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    Su, Gui-Jia [ORNL; Tang, Lixin [ORNL

    2007-01-01

    Electrical power systems in future hybrid and fuel cell vehicles may employ three voltage (14V, 42V and high voltage (HV)) nets. These will be necessary to accommodate existing 14V loads as well as efficiently handle new heavy loads at the 42V net and an electrical traction drive on the HV bus. A low-cost bi-directional dc-dc converter was proposed in (10) for connecting the three voltage nets. The converter consists of two half-bridges and a high-frequency transformer; thus minimizing the number of switching devices and their associated gate driver components. One salient feature is that the half-bridge on the 42V bus is also utilized to provide the 14V bus by operating its duty ratio around an atypical value of 1/3. This eliminates the need for an additional 14V/42V converter. Moreover, it makes use of the parasitic capacitance of the switches and the transformer leakage inductance for soft-switching; no extra active switches or passive resonant components are required. The use of half-bridges makes the topology suitable for interleaved multi-phase configurations as a means to increase the power level because the capacitor legs can be shared. This paper presents simulation and experimental results on an interleaved two-phase arrangement rated at 4.5 kW. Also discussed are the benefits of operating with the atypical duty ratio on the transformer and a preferred multi-phase configuration to minimize capacitor ripple currents.

  3. DC high voltage to drive helium plasma jet comprised of repetitive streamer breakdowns

    CERN Document Server

    Wang, Xingxing

    2016-01-01

    This paper demonstrates and studies helium atmospheric pressure plasma jet comprised of series of repetitive streamer breakdowns, which is driven by a pure DC high voltage (auto-oscillations). Repetition frequency of the breakdowns is governed by the geometry of discharge electrodes/surroundings and gas flow rate. Each next streamer is initiated when the electric field on the anode tip recovers after the previous breakdown and reaches the breakdown threshold value of about 2.5 kV/cm. Repetition frequency of the streamer breakdowns excited using this principle can be simply tuned by reconfiguring the discharge electrode geometry. This custom-designed type of the helium plasma jet, which operates on the DC high voltage and is comprised of the series of the repetitive streamer breakdowns at frequency about 13 kHz, is demonstrated.

  4. A Current-Mode Buck DC-DC Converter with Frequency Characteristics Independent of Input and Output Voltages Using a Quadratic Compensation Slope

    Science.gov (United States)

    Sai, Toru; Sugimoto, Yasuhiro

    By using a quadratic compensation slope, a CMOS current-mode buck DC-DC converter with constant frequency characteristics over wide input and output voltage ranges has been developed. The use of a quadratic slope instead of a conventional linear slope makes both the damping factor in the transfer function and the frequency bandwidth of the current feedback loop independent of the converter's output voltage settings. When the coefficient of the quadratic slope is chosen to be dependent on the input voltage settings, the damping factor in the transfer function and the frequency bandwidth of the current feedback loop both become independent of the input voltage settings. Thus, both the input and output voltage dependences in the current feedback loop are eliminated, the frequency characteristics become constant, and the frequency bandwidth is maximized. To verify the effectiveness of a quadratic compensation slope with a coefficient that is dependent on the input voltage in a buck DC-DC converter, we fabricated a test chip using a 0.18µm high-voltage CMOS process. The evaluation results show that the frequency characteristics of both the total feedback loop and the current feedback loop are constant even when the input and output voltages are changed from 2.5V to 7V and from 0.5V to 5.6V, respectively, using a 3MHz clock.

  5. Dynamical Localization in a Two-Electron Quantum Dot Molecule Biased by a dc Voltage

    Institute of Scientific and Technical Information of China (English)

    王立民; 段素青; 赵宪庚; 刘承师; 马本堃

    2003-01-01

    We study the dynamics of two interacting electrons in a coupled-quantum-dot system with a time-dependent external electric field. The numerical results of the two-particle states reveal that the dynamical localization still exists under appropriate dc and ac voltage amplitudes. Such localization is different from the stationary localization phenomenon. Our conclusion is instructive for the field of quantum function devices.

  6. Development of a Novel Bidirectional DC/DC Converter Topology with High Voltage Conversion Ratio for Electric Vehicles and DC-Microgrids

    Directory of Open Access Journals (Sweden)

    Ching-Ming Lai

    2016-05-01

    Full Text Available The main objective of this paper was to study a bidirectional direct current to direct current converter (BDC topology with a high voltage conversion ratio for electric vehicle (EV batteries connected to a dc-microgrid system. In this study, an unregulated level converter (ULC cascaded with a two-phase interleaved buck-boost charge-pump converter (IBCPC is introduced to achieve a high conversion ratio with a simpler control circuit. In discharge state, the topology acts as a two-stage voltage-doubler boost converter to achieve high step-up conversion ratio (48 V to 385 V. In charge state, the converter acts as two cascaded voltage-divider buck converters to achieve high voltage step-down conversion ratio (385 V to 48 V. The features, operation principles, steady-state analysis, simulation and experimental results are made to verify the performance of the studied novel BDC. Finally, a 500 W rating prototype system is constructed for verifying the validity of the operation principle. Experimental results show that highest efficiencies of 96% and 95% can be achieved, respectively, in charge and discharge states.

  7. Microloss DC Voltage Regulator%微功耗直流稳压器

    Institute of Scientific and Technical Information of China (English)

    郁百超

    2012-01-01

    The voltage interception and voltage compensation was employed to stabilize or regulate DC voltage, whose distinguished characteristic is that the core 'circuit could avoid the electro-magnetic interferences (EMI) to the grid for no use of pulse-width modulation (PWM). Therefore its power consumption is kept as low as possible while its lifetime can be as long as possible with an efficiency as high as 99.5%. Moreover, it is safe and reliable, green and energy-conserving and its simple circuit is easy to fabricate. Its cost, volume, weight, and power consumption are about only ten percent of those of the traditional DC voltage regulators.%微功耗直流稳压器采用电压切割和电压补偿的方法,实现了对直流电压的稳定或调整,该直流稳压器最大特点是,主电路不采用PWM脉宽调制,不产生EMI干扰,因此功耗极小而寿命极长,输出直流电压调整率高,效率高达99.5%,安全可靠,节能环保,电路简单,制作安装容易,其成本、体积、重量、功耗都是传统直流稳压器的十分之一。

  8. High voltage threshold for stable operation in a dc electron gun

    Science.gov (United States)

    Yamamoto, Masahiro; Nishimori, Nobuyuki

    2016-07-01

    We report clear observation of a high voltage (HV) threshold for stable operation in a dc electron gun. The HV hold-off time without any discharge is longer than many hours for operation below the threshold, while it is roughly 10 min above the threshold. The HV threshold corresponds to the minimum voltage where discharge ceases. The threshold increases with the number of discharges during HV conditioning of the gun. Above the threshold, the amount of gas desorption per discharge increases linearly with the voltage difference from the threshold. The present experimental observations can be explained by an avalanche discharge model based on the interplay between electron stimulated desorption (ESD) from the anode surface and subsequent secondary electron emission from the cathode by the impact of ionic components of the ESD molecules or atoms.

  9. Analog Circuit Design Low Voltage Low Power; Short Range Wireless Front-Ends; Power Management and DC-DC

    CERN Document Server

    Roermund, Arthur; Baschirotto, Andrea

    2012-01-01

    The book contains the contribution of 18 tutorials of the 20th workshop on Advances in Analog Circuit Design.  Each part discusses a specific to-date topic on new and valuable design ideas in the area of analog circuit design. Each part is presented by six experts in that field and state of the art information is shared and overviewed. This book is number 20 in this successful series of Analog Circuit Design, providing valuable information and excellent overviews of Low-Voltage Low-Power Data Converters - Chaired by Prof. Anderea Baschirotto, University of Milan-Bicocca Short Range Wireless Front-Ends - Chaired by Prof. Arthur van Roermund, Eindhoven University of Technology Power management and DC-DC - Chaired by Prof. M. Steyaert, Katholieke University Leuven Analog Circuit Design is an essential reference source for analog circuit designers and researchers wishing to keep abreast with the latest development in the field. The tutorial coverage also makes it suitable for use in an advanced design.

  10. Comparative Studyon DC Flashover Characteristics of Iced Insulators with Various Test Methods

    Institute of Scientific and Technical Information of China (English)

    HU Jianlin; LUO Mingwu; JIANG Xingliang; SUN Caixin; ZHANG Zhijin; SHU Lichun

    2012-01-01

    In this paper,the DC flashover characteristics of iced insulator strings were explored in the multi-functional artificial climate chamber by four methods,namely,the average flashover voltage method,the minimum flashover voltage method(U-curve method),the maximum withstand method and the 50% withstand method.Typical DC porcelain insulator strings and composite insulators were used as specimens.The results indicate that the average flashover voltage and the minimum flashover voltage obtained by the average flashover voltage method and the minimum flashover voltage method,respectively,obey a normal distribution.The 50% flashover voltage could be gained by the two methods with a minimal test number of nine and were about 8.0%~9.8% and 3.8%~5.9% respectively higher than that gained by the 50% withstand method.This justified the feasibility of employing the Ucurve method and the average flashover voltage method to study the flashover characteristics of iced insulators and their affecting factors.

  11. Investigations of surface characterization of silicone rubber due to tracking phenomena under a.c. and d.c. voltages

    Indian Academy of Sciences (India)

    Uma Maheswar Rao; S S M S Abdul Majeed; C Venkataseshaiah; R Sarathi

    2002-11-01

    In the present work, tracking phenomena has been studied with silicone rubber material under the a.c. and d.c. voltages following IEC-587 standards. The surface condition of the tracked zone was analysed using wide angle X-ray diffraction (WAXD) and thermogravimetric differential thermal analysis (TG–DTA) studies. The tracking time was different for a.c. and d.c. voltages.

  12. Fault Analysis of DC Voltage Dividers in Xiangjiaba--Shanghai ±800 kV UHVDC Project

    Institute of Scientific and Technical Information of China (English)

    LI Fengqi; SHE Zhengqiu; LOU Dianqiang; Rajendra Iyer; Urban Astrom

    2012-01-01

    Transient DC voltage measurement error has been observed several times ever since Xiangjiaba--Shanghai ±800 kV UHVDC project started its commercial operation. The measurement error causes considerable disturbances to the AC networks. By analyzing the time frequency record, simulating faults at different positions of the divider, and testing the gas in voltage dividers, the fault is located and then is proved to be some partial discharges inside DC voltage dividers. The reason of the internal flashes and the solution to the problem is also discussed in this paper. The conclusion is that instead of N2 , SF6 should be used for the internal insulation of high voltage DC voltage dividers.

  13. Analytical evaluation of DC capacitor RMS current and voltage ripple in neutral-point clamped inverters

    Indian Academy of Sciences (India)

    K S GOPALAKRISHNAN; SANTOSH JANAKIRAMAN; SOUMITRA DAS; G NARAYANAN

    2017-06-01

    The sizing of the DC-link capacitor in a three-level inverter is based on the RMS current flowing through it. This paper analyses the DC-link capacitor RMS current in a neutral-point clamped (NPC) inverter and expresses the same as a function of modulation index, line-side current amplitude and power factor. Analytical closed-form expressions are derived for the capacitor RMS current for single-phase half-bridge,single-phase full-bridge and three-phase three-leg topologies of a three-level inverter. The worst-case capacitor current stress is determined for each topology based on the analytical expressions. Further, analytical expressions are derived for the RMS values of low-frequency and high-frequency capacitor currents. These expressions are then used to estimate voltage ripple across the DC capacitor for sinusoidally modulated three-phase NPC inverter. The analytical expressions for the RMS current and voltage ripple are validated experimentally over a wide range of operating points.

  14. Study of DC Circuit Breaker of H2-N2 Mixture Gas for High Voltage

    Science.gov (United States)

    Shiba, Yuji; Morishita, Yukinaga; Kaneko, Shuhei; Okabe, Shigemitsu; Mizoguchi, Hitoshi; Yanabu, Satoru

    Global warming caused by CO2 etc. is a field where the concern is very high. Especially, automobile emissions are problem for it. Therefore, the hybrid car is widely development and used recently. Hybrid car used electric power and gasoline. So, the car reduces CO2. Hybrid car has engine and motor. To rotate the motor, hybrid car has battery. This battery is large capacity. Therefore, the relay should interrupt high DC current for the switch of the motor and the engine. So, hybrid car used hydrogen gas filling relay We studied interruption test for the research of a basic characteristic of hydrogen gas. DC current has not current zero point. So, it is necessary to make the current zero by high arc voltage and forcible current zero point. The loss coefficient and arc voltage of hydrogen is high. Therefore, we studied interruption test for used high arc voltage. We studied interruption test and dielectric breakdown test of air, pure Hydrogen, and Hydrogen- nitrogen mixture gas. As a result, we realized H2-N2(80%-20%) is the best gas.

  15. Influence of Load Modes on Voltage Stability of Receiving Network at DC/AC System

    Directory of Open Access Journals (Sweden)

    Mao Chizu

    2016-01-01

    Full Text Available This paper analyses influence of load modes on DC/AC system. Because of widespread use of HVDC, DC/AC system become more complex than before and the present modes used in dispatch and planning departments are not fit in simulation anymore. So it is necessary to find load modes accurately reflecting characteristics of the system. For the sake of the voltage stability, commutation failure, etc. the practical example of the receiving network in a large DC/AC system in China is simulated with BPA, and the influence of Classical Load Mode (CLM and Synthesis load model (SLM on simulation results is studies. Furthermore, some important parameters of SLM are varied respectively among an interval to analyse how they affect the system. According to this practical examples, the result is closely related to load modes and their parameters, and SLM is more conservative but more reasonable than the present modes. The consequences indicate that at critical states, micro variation in parameters may give rise to change in simulation results radically. Thus, correct mode and parameters are important to enhance simulation accuracy of DC/AC system and researches on how they affect the system make senses.

  16. Development Ground Fault Detecting System for D.C Voltage Line

    Energy Technology Data Exchange (ETDEWEB)

    Kim Taek Soo; Song Ung Il; Gwon, Young Dong; Lee Hyoung Kee [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

    1996-12-31

    It is necessary to keep the security of reliability and to maximize the efficiency of maintenance by prompt detection of a D.C feeder ground fault point at the built ed or a building power plants. At present, the most of the power plants are set up the ground fault indicator lamp in the monitor room. If a ground fault occurs on DC voltage feeder, a current through the ground fault relay is adjusted and the lamps have brightened while the current flows the relay coil. In order to develop such a system, it is analyzed a D.C feeder ground circuit theoretically and studied a principles which can determine ground fault point or a polarity discrimination and a phase discrimination of the line. So, the developed system through this principles can compute a resistance ground fault current and a capacitive ground fault current. It shows that the system can defect a ground fault point or a bad insulated line by measuring a power plant D.C feeder insulation resistance at the un interruptible power status, and therefore the power plant could protect an unexpected service interruption . (author). 18 refs., figs.

  17. Modeling and Analysis of a Low-Voltage DC Distribution System

    Directory of Open Access Journals (Sweden)

    Joon Han

    2015-09-01

    Full Text Available It is well known that the Low-Voltage DC (LVDC distribution system is a promising topology as a future smart distribution system due to its high efficiency and reliability. However, there are still some challenges in the construction and implementation of an LVDC system. For practical application of the LVDC system, therefore, it is necessary to perform any simulation in advance by considering various conditions that can occur in an LVDC system. In order to provide a foundation for analyzing a DC system, this paper presents an LVDC distribution system model including essential components such as power electronic devices, Distributed Energy Resource (DER, and Energy Storage System (ESS, which can be considered for implementation in an LVDC system using Electro-Magnetic Transient Program (EMTP software. Moreover, an analysis of the characteristic in both the steady state and the transient state is conducted in an LVDC distribution system.

  18. 1 kW, 9 kV dc-dc converter module with time-sharing control of output voltage and input current

    Energy Technology Data Exchange (ETDEWEB)

    Borgatti, R.; Stefani, R.; Bressan, O.; Bicciato, F. [F.I.A.R. Electronic Systems Group, Milan (Italy). Avionics Div.; Tenti, P.; Rossetto, L. [Univ. of Padova (Italy). Dept. of Electrical Engineering

    1993-10-01

    The paper describes a dc-dc power module based on a single-stage current-fed converter structure. Control is made according to a time-sharing strategy allowing simultaneous regulation of output voltage and input current. This solution is suitable for high-performance space and avionic applications, giving high efficiency, compactness, and accuracy, speed and robustness of control. Theoretical analysis, design criteria, and experimental results are reported. Application to radar supplies is discussed.

  19. The design of the Sepic dc voltage stabilizer%Sepic直流稳压器的设计

    Institute of Scientific and Technical Information of China (English)

    宋连庆; 宋淑淑

    2015-01-01

    Designed a range of input voltage is 130~300 V, output 12 V/8 A, the working frequency of 100 kHz Sepic dc voltage stabilizer, this paper expounds the main circuit topology structure, and design input protection circuit sauxiliary power supply circuit, PWM control circuit, optical coupling isolation drive circuit and output over voltage, over current protection circuit, feedback method and pulse width modulation technology is applied to implement the stability of voltage and current output.%设计了一种输入交流电压范围为130~300 V,输出12 V/8 A、工作频率为100 kHz的Sepic直流稳压器,阐述了主电路的拓扑结构,并设计了输入保护电路、辅助电源电路、PWM控制电路、光耦隔离驱动电路与输出过压、过流保护电路,应用反馈手段和脉宽调制技术实现电压、电流的稳定。

  20. LOW VOLTAGE NETWORKS INSULATION MONITORING WITH TWO AND THREE VOLTMETER READOUTS METHODS

    Directory of Open Access Journals (Sweden)

    P. Olszowiec

    2016-11-01

    Full Text Available Purpose. In the paper there are described methods of two and three voltmeter readouts for insulation resistance periodic measurement in live DC and AC/DC IT networks. A new measuring method for AC/DC networks is proposed. Application of a novel algorithm for shortening of measurement cycle is explained. Methodology. All methods of two and three voltmeter readouts consist in connection of a resistor and measurement of mean value of network’s fixed point-to-ground voltages. Results. A new algorithm implemented in KDZ-3 device enables determination of steady-state voltage of a DC network’s pole much faster than in other exploited systems. Originality. In author’s modification of two voltmeter readouts method, line-to-ground voltage mean value is measured at AC side of AC/DC network. This innovation has not been applied for implementation of periodic insulation monitoring in AC/DC IT networks yet. Practical value. The use of author’s innovation will allow to execute measurements at AC side of AC/DC IT networks which might be necessary if rectifier’s output circuits are unavailable. Shortening of measurement cycle duration of two or three voltmeter readouts method’s is of great importance in networks with high capacitance.

  1. Evaluation of Niobium as Candidate Electrode Material for DC High Voltage Photoelectron Guns

    Science.gov (United States)

    BastaniNejad, M.; Mohamed, Abdullah; Elmustafa, A. A.; Adderley, P.; Clark, J.; Covert, S.; Hansknecht, J.; Hernandez-Garcia, C.; Poelker, M.; Mammei, R.; hide

    2012-01-01

    The field emission characteristics of niobium electrodes were compared to those of stainless steel electrodes using a DC high voltage field emission test apparatus. A total of eight electrodes were evaluated: two 304 stainless steel electrodes polished to mirror-like finish with diamond grit and six niobium electrodes (two single-crystal, two large-grain, and two fine-grain) that were chemically polished using a buffered-chemical acid solution. Upon the first application of high voltage, the best large-grain and single-crystal niobium electrodes performed better than the best stainless steel electrodes, exhibiting less field emission at comparable voltage and field strength. In all cases, field emission from electrodes (stainless steel and/or niobium) could be significantly reduced and sometimes completely eliminated, by introducing krypton gas into the vacuum chamber while the electrode was biased at high voltage. Of all the electrodes tested, a large-grain niobium electrode performed the best, exhibiting no measurable field emission (< 10 pA) at 225 kV with 20 mm cathode/anode gap, corresponding to a field strength of 18:7 MV/m.

  2. Control model design to limit DC-link voltage during grid fault in a dfig variable speed wind turbine

    Science.gov (United States)

    Nwosu, Cajethan M.; Ogbuka, Cosmas U.; Oti, Stephen E.

    2017-08-01

    This paper presents a control model design capable of inhibiting the phenomenal rise in the DC-link voltage during grid- fault condition in a variable speed wind turbine. Against the use of power circuit protection strategies with inherent limitations in fault ride-through capability, a control circuit algorithm capable of limiting the DC-link voltage rise which in turn bears dynamics that has direct influence on the characteristics of the rotor voltage especially during grid faults is here proposed. The model results so obtained compare favorably with the simulation results as obtained in a MATLAB/SIMULINK environment. The generated model may therefore be used to predict near accurately the nature of DC-link voltage variations during fault given some factors which include speed and speed mode of operation, the value of damping resistor relative to half the product of inner loop current control bandwidth and the filter inductance.

  3. Voltage stability, bifurcation parameters and continuation methods

    Energy Technology Data Exchange (ETDEWEB)

    Alvarado, F.L. [Wisconsin Univ., Madison, WI (United States)

    1994-12-31

    This paper considers the importance of the choice of bifurcation parameter in the determination of the voltage stability limit and the maximum power load ability of a system. When the bifurcation parameter is power demand, the two limits are equivalent. However, when other types of load models and bifurcation parameters are considered, the two concepts differ. The continuation method is considered as a method for determination of voltage stability margins. Three variants of the continuation method are described: the continuation parameter is the bifurcation parameter the continuation parameter is initially the bifurcation parameter, but is free to change, and the continuation parameter is a new `arc length` parameter. Implementations of voltage stability software using continuation methods are described. (author) 23 refs., 9 figs.

  4. A kind of output voltage compensation design of low-voltage and high-current dc power supply%一种低压大电流直流电源的输出电压补偿设计

    Institute of Scientific and Technical Information of China (English)

    谢记华; 张锦鹏; 王金芳

    2015-01-01

    This paper is based on a kind of low-voltage&high-current power supply designed by VICOR DC-DC converter, Through sampling the loading point voltage and applying feedback circuit to adjust the voltage of converter to compensate the drop of the load in high current transmission, so as to achieve the stability of loading point voltage. This paper analyses the basic principle of compensation circuit in detail, introduces the component selection method and proves the feasibility of the circuit by designing and testing voltage compensation circuit.%文中基于一种采用VICOR DC-DC转换器设计的低压大电流直流电源,通过采样负载点电压,外加反馈电路来调节转换器输出电压,以补偿在大电流传输时负载线上的电压降,从而达到稳定负载点电压的目的。本文详细分析了电压补偿电路的原理,介绍了元器件选择方法,并通过电压补偿电路的设计和测试验证了该电路的可行性。

  5. Design of Neutral-Point Voltage Controller of a Three-level NPC Inverter with Small DC-Link Capacitors

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, S.

    2013-01-01

    A Neutral-Point-Clamped (NPC) three-level inverter with small dc-link capacitors is presented in this paper. The inverter requires zero average neutral-point current for stable neutral-point voltage. The small dc-link capacitors may not maintain capacitor voltage balance, even with zero neutral-point...... current. This may happen due to nonlinearities present in the circuit. This requires a fast control of the neutral-point voltage. A simple carrier based modulation strategy which allows modeling of the neutral-point voltage dynamics as a continuous function of power drawn from the inverter is proposed....... This continuous model shows that the neutral-point current is proportional to the power drawn from the inverter, and it enables the use of well established classical control theory for the neutral-point voltage controller design. A simple PI (proportional integral) controller is designed for the neutral-point...

  6. Loading Analysis of Modular Multi-level Converter for Offshore High-voltage DC Application under Various Grid Faults

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Loh, Poh Chiang;

    2016-01-01

    The modular multi-level converter has become an interesting candidate in high-voltage DC systems due to its higher voltage levels and modular construction. Low-voltage ride-through is an important grid requirement for modular multi-level converter–high-voltage DC since not only causes control...... challenges but may also result in overstressed components for the modular multi-level converter. However, the thermal loading of the modular multi-level converter under various grid faults has not yet been clarified. In this article, the power loss and thermal performance of the modular multi-level converter...... during grid voltage dips are studied. The impacts of two typical grid faults to the modular multi-level converter in terms of operating and loading conditions are analytically researched and simulated. It has been found that the operating and loading conditions of the modular multi-level converter under...

  7. Three Phase Two Leg Neutral Point Clamped Converter with output DC Voltage Regulation and Input Power Factor Correction

    Directory of Open Access Journals (Sweden)

    Bogimi Sirisha

    2012-03-01

    Full Text Available In this paper, a three-phase two leg neutral point clamped (NPC converter is presented for power factor correction and dc-link voltage regulation. The adopted converter has simpler circuit configuration and less number of power switches compared to three-level PWM converter. In this circuit configuration, only eight power switches and four clamping diodes with voltage stress of half the dc bus voltage are used. A simplified space vector pulse width modulation scheme (SVPWM is also adopted to track the line current commands. A reference voltage vector is generated on the ac terminal for drawing the sinusoidal line currents with unity power factor. This algorithm reduces the time required to calculate the switching time durations of voltage vectors. The simulation results have been presented to verify the validity and effectiveness of the proposed control strategy.

  8. Development of Voltage Regulation Plan by Composing Subsystem with the SFES for DC On-line Electric Vehicle

    Science.gov (United States)

    Jung, S.; Lee, J. H.; Yoon, M.; Lee, H.; Jang, G.

    The study of the application process of the relatively small size 'Superconducting Flywheel Energy Storage (SFES)' system is conducted to regulate voltage fluctuation of the DC On-Line Electric Vehicle (OLEV) system, which is designed by using DC power system network. It is recommended to construct the power conversion system nearby the substation because the charging system is under the low voltage. But as the system is usually built around urban area and it makes hard to construct the subsystems at every station, voltage drop can occur in power supply inverter that is some distance from the substation. As the alternative of this issue, DC distribution system is recently introduced and has possibility to solve the above issue. In this paper, SFES is introduced to solve the voltage drop under the low voltage distribution system by using the concept of the proposed DC OLEV which results in building the longer distance power supply system. The simulation to design the SFES by using DC power flow analysis is carried out and it is verified in this paper.

  9. Effect of applied dc bias voltage on composition, chemical bonding and mechanical properties of carbon nitride films prepared by PECVD

    Institute of Scientific and Technical Information of China (English)

    LI Hong-xuan; XU Tao; HAO Jun-ying; CHEN Jian-min; ZHOU Hui-di; XUE Qun-ji; LIU Hui-wen

    2004-01-01

    Carbon nitride films were deposited on Si (100) substrates using plasma-enhanced chemical vapor deposition (PECVD) technique from CH4 and N2 at different applied dc bias voltage. The microstructure, composition and chemical bonding of the resulting films were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The mechanical properties such as hardness and elastic modulus of the films were evaluated using nano-indentation. As the results, the Raman spectra, showing the G and D bands, indicate the amorphous structure of the films. XPS and FTIR measurements demonstrate the existence of various carbon-nitride bonds in the films and the hydrogenation of carbon nitride phase. The composition ratio of N to C, the nano-hardness and the elastic modulus of the carbon nitride films increase with increasing dc bias voltage and reach the maximums at a dc bias voltage of 300 V, then they decrease with further increase of the dc bias voltage. Moreover, the XRD analyses indicate that the carbon nitride film contains some polycrystalline C3N4 phase embedded in the amorphous matrix at optimized deposition condition of dc bias voltage of 300 V.

  10. TiN coated aluminum electrodes for DC high voltage electron guns

    Energy Technology Data Exchange (ETDEWEB)

    Mamun, Md Abdullah A.; Elmustafa, Abdelmageed A., E-mail: aelmusta@odu.edu [Department of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, Virginia 23529 and The Applied Research Center, Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Taus, Rhys [Department of Physics, Loyola Marymount University, Los Angeles, California 90045 (United States); Forman, Eric; Poelker, Matthew [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)

    2015-05-15

    Preparing electrodes made of metals like stainless steel, for use inside DC high voltage electron guns, is a labor-intensive and time-consuming process. In this paper, the authors report the exceptional high voltage performance of aluminum electrodes coated with hard titanium nitride (TiN). The aluminum electrodes were comparatively easy to manufacture and required only hours of mechanical polishing using silicon carbide paper, prior to coating with TiN by a commercial vendor. The high voltage performance of three TiN-coated aluminum electrodes, before and after gas conditioning with helium, was compared to that of bare aluminum electrodes, and electrodes manufactured from titanium alloy (Ti-6Al-4V). Following gas conditioning, each TiN-coated aluminum electrode reached −225 kV bias voltage while generating less than 100 pA of field emission (<10 pA) using a 40 mm cathode/anode gap, corresponding to field strength of 13.7 MV/m. Smaller gaps were studied to evaluate electrode performance at higher field strength with the best performing TiN-coated aluminum electrode reaching ∼22.5 MV/m with field emission less than 100 pA. These results were comparable to those obtained from our best-performing electrodes manufactured from stainless steel, titanium alloy and niobium, as reported in references cited below. The TiN coating provided a very smooth surface and with mechanical properties of the coating (hardness and modulus) superior to those of stainless steel, titanium-alloy, and niobium electrodes. These features likely contributed to the improved high voltage performance of the TiN-coated aluminum electrodes.

  11. A distinct sodium channel voltage-sensor locus determines insect selectivity of the spider toxin Dc1a

    Science.gov (United States)

    Bende, Niraj S.; Dziemborowicz, Sławomir; Mobli, Mehdi; Herzig, Volker; Gilchrist, John; Wagner, Jordan; Nicholson, Graham M.; King, Glenn F.; Bosmans, Frank

    2014-07-01

    β-Diguetoxin-Dc1a (Dc1a) is a toxin from the desert bush spider Diguetia canities that incapacitates insects at concentrations that are non-toxic to mammals. Dc1a promotes opening of German cockroach voltage-gated sodium (Nav) channels (BgNav1), whereas human Nav channels are insensitive. Here, by transplanting commonly targeted S3b-S4 paddle motifs within BgNav1 voltage sensors into Kv2.1, we find that Dc1a interacts with the domain II voltage sensor. In contrast, Dc1a has little effect on sodium currents mediated by PaNav1 channels from the American cockroach even though their domain II paddle motifs are identical. When exploring regions responsible for PaNav1 resistance to Dc1a, we identified two residues within the BgNav1 domain II S1-S2 loop that when mutated to their PaNav1 counterparts drastically reduce toxin susceptibility. Overall, our results reveal a distinct region within insect Nav channels that helps determine Dc1a sensitivity, a concept that will be valuable for the design of insect-selective insecticides.

  12. Surface Partial Discharge Characteristics of Oil-paper Insulation Under Combined AC-DC Voltage

    Institute of Scientific and Technical Information of China (English)

    SHA Yanchao; ZHOU Yuanxiang; NIE Dexin; WU Zhirong; DENG Jiangang; LU Licheng

    2013-01-01

    The valve side windings of converter transformers bear AC,DC,impulse,and reversal-polarity voltages during operation,which could result in serious insulation problems of the equipment.By performing experiments with surface discharge model of oil-paper insulation at 80 ℃ under combined AC-DC voltage for 200 h,we studied the spectrums and statistical parameters of partial discharges at different discharge stages.Furthermore,some fingerprint parameters were calculated in order to estimate the development situation of partial discharge,while the characteristic gases dissolved in the transformer oil were measured by gas chromatography.The surface discharges in the experiments were observed using a high speed camera,and a full discharge process could be marked off into four stages as follows.①The elementary stage.When a partial discharge occurs near electrodes,electrical charges are injected into the region near electrodes and causing bubble generation.②Due to their high resistivity and low dielectric constant,the bubbles would bare the major part of the voltage applied to samples.Therefore,discharge happens inside the small bubbles,and it emits a lot of light.③Micmmolecules of gas are produced in discharge,and further ionization in the transformer oil takes place simultaneously when high-energy electrons collide with oil molecules.④The carrier charge moves forward to electrodes driven by the applied electric field,till they neutralize with the charge from electrodes,and hence discharge channels are formed subsequently.

  13. An IFOC-DSVPWM Based DC-Link Voltage Compensation of Z-Source Inverter Fed Induction Motor Drive for EVs

    Directory of Open Access Journals (Sweden)

    Ananda Kumar Akkarapaka

    2015-01-01

    Full Text Available The drop in DC-link voltage of adjustable speed drives (ASD occurs mainly due to the increase in output power demands. This may lead to inefficient operation and eventually the tripping of the drive. This paper presents a Double Space Vector Pulse Width Modulation (DSVPWM technique for boosting and compensating the DC-link voltage of Z-source inverter (ZSI. The DSVPWM technique estimates the required shoot through period of the Z-source inverter to maintain the DC-link voltage constant at the desired level through capacitor voltage control. The DSVPWM can obtain maximum boost at any given modulation index in comparison to simple boost control (SBC method. It also utilizes the dead time more effectively. The speed control of the ZSI fed induction motor drive is done by employing indirect field-oriented (IFO control method. A 32-bit DSP (TMS320F28335 is used to implement the IFOC-DSVPWM method for ZSI. The power structure and the modulation technique are well suited for electric vehicle application.

  14. An isolated bridgeless AC-DC PFC converter using a LC resonant voltage doubler rectifier

    Science.gov (United States)

    Lee, Sin-woo; Do, Hyun-Lark

    2016-12-01

    This paper proposed an isolated bridgeless AC-DC power factor correction (PFC) converter using a LC resonant voltage doubler rectifier. The proposed converter is based on isolated conventional single-ended primary inductance converter (SEPIC) PFC converter. The conduction loss of rectification is reduced than a conventional one because the proposed converter is designed to eliminate a full-bridge rectifier at an input stage. Moreover, for zero-current switching (ZCS) operation and low voltage stresses of output diodes, the secondary of the proposed converter is designed as voltage doubler with a LC resonant tank. Additionally, an input-output electrical isolation is provided for safety standard. In conclusion, high power factor is achieved and efficiency is improved. The operational principles, steady-state analysis and design equations of the proposed converter are described in detail. Experimental results from a 60 W prototype at a constant switching frequency 100 kHz are presented to verify the performance of the proposed converter.

  15. [Spatial distribution of electrons with high energy in atmospheric pressure glow discharge excited by DC voltage].

    Science.gov (United States)

    Liu, Zhi-qiang; Jia, Peng-ying; Liu, Tie

    2013-09-01

    Atmospheric pressure glow discharge excited by a DC voltage was realized in a 6 mm air gap by using a needle-water electrode discharge device. The atompheric pressure glow discharge has characteristic regions such as a cathode fall, a negative glow, a Faraday dark space, a positive column and an anode glow. The discharge is a normal glow through analyzing its voltage-current curve. The emission intensity of 337.1 nm spectral line from the second positive system of N2 was investigated because it can indicate the electron density with high energy. Results show that the maxima of high energy electrons appears in the vicinity of the needle tip, and it almost remains constant at other locations. The density of high energy electrons decreases with increasing the voltage. Similarly, it decreases with increasing the value of the ballast resistor. Oxygen atom is important for the sterilization and disinfection. The distribution of oxygen atom was also investigated by optical emission spectroscopy. It was found that the oxygen distribution is similar with the distribution of high energy electrons. These results are important for the application of atmospheric pressure glow discharge in environmental protection and biological treatment.

  16. A fully on-chip three-terminal switched-capacitor DC-DC converter for low-voltage CMOS LSIs

    Science.gov (United States)

    Kojima, Yuta; Hirose, Tetsuya; Tsubaki, Keishi; Ozaki, Toshihiro; Asano, Hiroki; Kuroki, Nobutaka; Numa, Masahiro

    2016-04-01

    In this paper, we present a fully on-chip switched-capacitor DC-DC converter for low-voltage CMOS LSIs. The converter has three terminals of input, ground, and output, by developing control circuits with fully on-chip configuration. We employ an ultra low-power nanoampere bias current and voltage reference circuit to achieve ultra low-power dissipation of control circuits. It enables us to realize a highly efficient power conversion circuit at light-load-current applications. The converter achieves highly efficient and robust voltage conversion using a pulse frequency modulation control circuit and a start-up/fail-safe circuit. Measurement results demonstrated that the converter can convert a 3.0 V input into 1.2 V output successfully. The start-up and fail-safe operations were confirmed through the measurement. The efficiency was more than 50% in the range of 2-6 µA load current.

  17. Zero-Voltage Switching PWM Strategy Based Capacitor Current-Balancing Control for Half-Bridge Three-Level DC/DC Converter

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Zhang, Qi

    2017-01-01

    The current imbalance among the two input capacitors is one of the important issues of the half-bridge threelevel (HBTL) DC/DC converter, which would affect system performance and reliability. In this paper, a zero-voltage switching (ZVS) pulse-wide modulation (PWM) strategy including two operation...... modes is proposed. Based on the proposed ZVS PWM strategy, a capacitor current-balancing control is proposed for the HBTL DC/DC converter, where the currents on the two input capacitors can be kept balanced by alternating the two operation modes of the proposed ZVS PWM strategy. Therefore, the proposed...... control strategy can improve the performance and reliability of the converter in the aspect of balancing the thermal stresses and lifetimes among the two input capacitors. Finally, simulation and experimental studies are conducted and results verify the proposed control strategy....

  18. A Feed-Forward Control Realizing Fast Response for Three-Branch Interleaved DC-DC Converter in DC Microgrid

    DEFF Research Database (Denmark)

    Wang, Haojie; Han, Minxiao; Yan, Wenli

    2016-01-01

    It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC) is proposed for stor......It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC) is proposed...... for storage batteries in DC microgrids. The working principle of TIDC is analyzed, and the factors influencing the response rate based on the dual-loop constant voltage control for TIDC are discussed, and then the method of feed-forward control for TIDC is studied to improve the response rate for load...

  19. On-chip frequency compensation with a dual signal path operational transconductance amplifier for a voltage mode control DC/DC converter

    Science.gov (United States)

    Qiang, Ye; Jie, Liu; Bing, Yuan; Xinquan, Lai; Ning, Liu

    2012-04-01

    A novel on-chip frequency compensation circuit for a voltage-mode control DC/DC converter is presented. By employing an RC network in the two signal paths of an operational transconductance amplifier (OTA), the proposed circuit generates two zeros to realize high closed-loop stability. Meanwhile, full on-chip integration is also achieved due to its simple structure. Hence, the number of off-chip components and the board space is greatly reduced. The structure of the dual signal path OTA is also optimized to help get a better transition response. Implemented in a 0.5 μm CMOS process, the voltage mode control DC/DC converter with the proposed frequency compensation circuit exhibits good stability. The test results show that both load and line regulations are less than 0.3%, and the output voltage can be recovered within 15 μs for a 400 mA load step. Moreover, the compensation components area is less than 2% of the die's area and the board space is also reduced by 11%. The efficiency of the whole chip can be up to 95%.

  20. Discharge ignition in the diaphragm configuration supplied by DC non-pulsing voltage

    Science.gov (United States)

    Hlochová, L.; Hlavatá, L.; Kozáková, Z.; Krčma, F.

    2016-05-01

    This work deals with the ignition of the discharge in the diaphragm configuration generated in water solutions containing supporting NaCl electrolyte. The reactor has volume of 110 ml and it is made of polycarbonate. HV electrodes made of stainless steel are placed in this reactor. Ceramic (Shapal-MTM) diaphragm is placed in the barrier separating the cathode and the anode space. An electric power source supplies the reactor by constant DC voltage up to 4 kV and electric current up to 300 mA. The discharge ignition is compared in the reactor with different sizes of diaphragms. Measurements are carried out in electrolyte solutions with the same conductivity. Images of plasma streamers and bubble formation are taken by an ICCD camera iStar 734. Electrical characteristics are measured by an oscilloscope LeCroy LT 374 L in order to determine breakdown moments at different experimental conditions.

  1. Voltage source ac-to-dc converters for high-power transmitters

    Science.gov (United States)

    Cormier, R.

    1990-01-01

    This work was done to optimize the design of the components used for the beam power supply, which is a component of the transmitters in the Deep Space Network (DSN). The major findings are: (1) the difference in regulation between a six-pulse and a twelve-pulse converter is at most 7 percent worse for the twelve-pulse converter; (2) the commutation overlap angle of a current source converter equals that of a voltage source converter with continuous line currents; (3) the sources of uncharacteristic harmonics are identified with SPICE simulation; (4) the use of an imperfect phase-shifting transformer for the twelve-pulse converter generates a harmonic at six times the line frequency; and (5) the assumptions usually made in analyzing converters can be relaxed with SPICE simulation. The results demonstrate the suitability of using SPICE simulation to obtain detailed performance predictions of ac-to-dc converters.

  2. 一种MMC-HVDC的直流电压波动抑制新方法%A New Approach for Suppressing DC Voltage Ripples of MMC-HVDC

    Institute of Scientific and Technical Information of China (English)

    周月宾; 江道灼; 胡鹏飞; 梁一桥; 郭捷; 林志勇

    2013-01-01

    针对柔性直流输电系统常规直流电压波动抑制算法中存在的缺陷,提出一种适用于模块化多电平换流器型高压直流输电系统(modular multilevel converter based high voltage direct current,MMC-HVDC)的直流电压波动抑制方法。该方法利用MMC特有的“储能”特性,在交流系统不对称时,控制 MMC 交、直流侧瞬时有功功率不再平衡,从而实现MMC交流侧电流依然保持对称运行,同时直流侧电压、电流和功率保持为恒定。为了实现上述控制功能与目标,建立三相交流系统不对称时 MMC 直流回路的模型,设计αβ0坐标系下以比例谐振调节器为基础的控制策略,且探讨MMC-HVDC中的协调控制问题。最后,搭建71电平背靠背 MMC-HVDC 系统模型进行数字仿真,结果验证了所提控制方法的有效性。%Since the common solution for eliminating DC voltage ripples in voltage sourced converter based high voltage direct current (VSC-HVDC) transmission system has some drawbacks, this paper proposed a new method applied to modular multilevel converter based high voltage direct current (MMC-HVDC). The method uses the sub-module energy storage capability in MMC, making the instantaneous active power between ac and dc side of MMC unequal under unbalanced AC system. Meanwhile, this method keeps the ac current balanced, and eliminates the DC voltage, DC current and DC power ripples as well. To fulfill such a control goal, according to the dc-loop model of MMC, a controller inαβ0 frame based on proportional resonant regulator was designed, and then the coordinated control strategy was discussed in case of MMC-HVDC. Finally, a back-to-back MMC-HVDC simulation model with 71 levels was built to verify the proposed controller. The results show that the controller works well under both balanced and unbalanced AC system.

  3. DC Fast-Charging Stations for EVs Controlled by a Local Battery Storage in Low Voltage Grids

    DEFF Research Database (Denmark)

    Gjelaj, Marjan; Træholt, Chresten; Hashemi Toghroljerdi, Seyedmostafa

    2017-01-01

    Electric Vehicles (EVs) are representing a great opportunity for major car manufacturers to invest resources in new technologies in order to support sustainable transportation and the reduction of 퐂퐎ퟐ emissions, in particular in the metropolitan areas. In recent years, the increasing penetration...... is equipped with a bidirectional AC/DC converter for feeding power back to the grid, two lithium batteries and a DC/DC converter. The proposed solution decreases the charging time of EVs and facilitates the integration of fast chargers in existing low voltage (LV) grids. The charging station can also be used...

  4. Analysis of crowbar action of high voltage DC power supply in the LHD ICRF system

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaodong [Southwestern Institute of Physics, Chengdu, Sichuan (China); Mutoh, T.; Kumazawa, R.; Watari, T.; Seki, T.; Shimpo, F.; Nomura, G.; Saito, K.

    1999-04-01

    Ion Cyclotron Range of Frequency (ICRF) heating will be applied to the Large Helical Device (LHD) at the 2nd experimental campaign in 1998. The LHD ICRF system is characterised by its high power (up to 12 MW at final stage) and steady state operation for more than 30 minutes. One of the main R and D items was a high power and steady state transmitter. The RF transmitter system having a wide frequency range from 25 to 95 MHz was designed and fabricated. This report describes the analysis of the DC power supply that contains the crowbar circuit protecting the tetrode from the arcing inside the tube. The DC power supply of the transmitter is fed from the commercial AC electric line which also supply the power to the LHD helical and poloidal coil power supplies. The voltage drop of the commercial line when the ICRF crowbar action happened is the serious problem for all experimental system. This paper analyses the crowbar effect on the commercial line with and without leakage transformer between the step-up transformer of transmitter and the commercial line. (author)

  5. New lightning current resistant low voltage limiting device for DC railway systems; Neue blitzstromtragfaehige Niederspannungsbegrenzungseinrichtung zum Potenzialschutz von Gleichstrombahnsystemen

    Energy Technology Data Exchange (ETDEWEB)

    Rocks, A.; Hinrichsen, V. [Technische Univ. Darmstadt (Germany). Fachgebiet Hochspannungstechnik; Richter, B. [ABB Schweiz AG, Wettingen (Switzerland); Zayer, H. [ESN Bahngeraete GmbH, Mannheim (Germany)

    2007-07-01

    In dc railway systems, low voltage limiters are applied to limit potential rises in case of failures by forming a permanent short-circuit between return circuit and Earth. These devices can usually carry only moderate lightning currents without permanent failure. In this contribution, a new concept is introduced which provides personal as well as equipment protection by combining a surge arrester and a low voltage limiter in a suited way. (orig.)

  6. Vacuum breakdown limit and quantum efficiency obtained for various technical metals using dc and pulsed voltage sources

    CERN Document Server

    Le Pimpec, F; Paraliev, M; Ganter, R; Hauri, C; Ivkovic, S; 10.1116/1.3478300

    2010-01-01

    For the SwissFEL project, an advanced high gradient low emittance gun is under development. Reliable operation with an electric field, preferably above 125 MV/m at a 4 mm gap, in the presence of an UV laser beam, has to be achieved in a diode configuration in order to minimize the emittance dilution due to space charge effects. In the first phase, a DC breakdown test stand was used to test different metals with different preparation methods at voltages up to 100 kV. In addition high gradient stability tests were also carried out over several days in order to prove reliable spark-free operation with a minimum dark current. In the second phase, electrodes with selected materials were installed in the 250 ns FWHM, 500 kV electron gun and tested for high gradient breakdown and for quantum efficiency using an ultra-violet laser.

  7. Comparative Study of Breakdown Voltage of Mineral, Synthetic and Natural Oils and Based Mineral Oil Mixtures under AC and DC Voltages

    Directory of Open Access Journals (Sweden)

    Abderrahmane Beroual

    2017-04-01

    Full Text Available This paper deals with a comparative study of AC and DC breakdown voltages of based mineral oil mixtures with natural and synthetic esters mainly used in high voltage power transformers. The goal was to analyze the performances of oil mixtures from the dielectric withstand point of view and to predict the behavior of transformers originally filled with mineral oil and re-filled with synthetic or natural ester oils when emptied for maintenance. The study concerns mixtures based on 20%, 50%, and 80% of natural and synthetic ester oils. AC breakdown voltages were measured using a sphere-sphere electrode system according to IEC 60156 specifications; the same specification was adopted for DC measurements since there is no standard specifications for this voltage waveform. A statistical analysis of the mean values, standard deviations, and histograms of breakdown voltage data was carried out. The Normal and Weibull distribution functions were used to analyze the experimental data and the best function that the data followed was used to estimate the breakdown voltage with risk of 1%, 10%, and 50% probability. It was shown that whatever the applied voltage waveforms, ester oils always have a significantly higher breakdown voltage than mineral oil. The addition of only 20% of natural or synthetic ester oil was sufficient to considerably increase the breakdown voltage of mineral oil. The dielectric strength of such a mixture is much higher than that of mineral oil alone and can reach that of ester oils. From the point of view of dielectric strength, the mixtures constitute an option for improving the performance of mineral oil. Thus, re-filling of transformers containing up to 20% mineral oil residues with ester oils, does not present any problem; it is even advantageous when considering only the breakdown voltage. Under AC, the mixtures with natural ester always follow the behavior of vegetable oil alone. With the exception of the 20% mixture of natural

  8. DC Bus Control of Back-to-Back Connected Two-Level PWM Rectifier-Five-Level NPC Voltage Source Inverter to Torque Ripple Reduction in Induction Motor

    Directory of Open Access Journals (Sweden)

    Abdelkrim Thameur

    2015-01-01

    Full Text Available This paper proposes a regulation method of back-to-back connected two-level PWM rectifier-five-level Voltage Source Inverter (VSI in order to reduce the torque ripple in induction motor. First part is dedicated to the presentation of the feedback control of two-level PWM rectifier. In the second part, five-level Neutral Point Clamped (NPC voltage source inverter balancing DC bus algorithm is presented. A theoretical analysis with a complete simulation of the system is presented to prove the excellent performance of the proposed technique.

  9. A Reconfigurable Series Resonant DC-DC Converter for Wide-Input and Wide-Output Voltages

    DEFF Research Database (Denmark)

    Shen, Yanfeng; Wang, Huai; Qin, Zian;

    2017-01-01

    This paper proposes a dual-bridge based LC series resonant dc-dc converter. The input inverter unit incorporates two bridge structures, i.e., a full-bridge inverter and a half-bridge inverter. For the output rectifier, it can be a full-bridge rectifier or an asymmetric half-bridge rectifier. Diff...

  10. Optimal Design of a Push-Pull-Forward Half-Bridge (PPFHB) Bidirectional DC–DC Converter With Variable Input Voltage

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

    2012-01-01

    This paper presents a low-cost bidirectional isolated dc–dc converte, derived from dual-active-bridge converter for the power sources with variable output voltage like supercapacitors. The proposed converter consists of push-pull-forward circuit half-bridge circuit (PPFHB) and a high-frequency tr...... by digital signal processor for comparison purpose. Detailed test results verify the theoretical analysis and demonstrate the validity of optimization design method....

  11. Point of collapse and continuation methods for large ac/dc systems

    Energy Technology Data Exchange (ETDEWEB)

    Canizares, C.A. (Escuela Politecnica Nacional, Quito (Ecuador)); Alvarado, F.L. (Univ. of Wisconsin, Madison, WI (United States))

    1993-02-01

    This paper describes the implementation of both Point of Collapse (PoC) methods and continuation methods for the computation of voltage collapse points (saddle-node bifurcations) in large ac/dc systems. A comparison of the performance of these methods is presented for real systems of up to 2,158 buses. The paper discusses computational details of the implementation of the PoC and continuation methods, and the unique challenges encountered due to the presence of high voltage direct current (HVDC) transmission, area interchange power control regulating transformers, and voltage and reactive power limits. The characteristics of a robust PoC power flow program are presented, and its application to detection and solution of voltage stability problems is demonstrated.

  12. DC-Link Compensation Method for Slim DC Link Drives Fed by Soft Grid

    DEFF Research Database (Denmark)

    Mathe, Laszlo; Rosendahl Andersen, Henrik; Lazar, Radu

    2010-01-01

    harmonic distortion (PWHD) of the line current are degraded, if resonance between the line impedance and the DC-link capacitance occurs. Likewise, the motor performance is affected negatively giving extra torque ripple, vibration and acoustic-noise emission. This paper proposes a novel DC-link compensation...... method, which ensures the stability of the slim DC-link on a soft grid. The proposed compensation method may be used for open- and closedloop control schemes, requiring a small overhead in the digital implementation....

  13. 大功率高压输入的IGBT高频直-直变换器%A High-Power DC-DC Converter for High Frequency High-Input Voltage Using IGBT

    Institute of Scientific and Technical Information of China (English)

    彭光凤; 郝荣泰

    1998-01-01

    For the high frequency and high-input-voltage (sometimes reaching several kilo-volts) converter, its switching devices - IGBTs′ voltage rating can not suit this requirement. In this paper, a new cascaded-inverter-units structure is proposed, in which the high-input-voltage is divided into several parts and each part corresponds to one DC-AC converter. So the IGBT′s operating voltages are equal to the voltage of each divided part. In order to increase the output power, the output-rectifier-diodes usually are used in parallel, a method to balance the current by changing the linking type between the transformer secondary windings and the output-rectifier diodes is recommended. This method fully utilizes the transformer leakage inductance to realize the current-sharing function. In this paper, operation of a high-input voltage, high-power DC-DC converter is described. Both experimental and simulation results are shown for a small-full-scale-model converter.%在高频高压输入的情况下,开关器件绝缘门极双极晶体管(IGBT)的耐压不能满足要求.文中论述了一种逆变单元串联的结构,它将输入的高电压分成几部分,每一部分有一个DC-AC逆变器.此时,IGBT的工作电压等于各部分电压.为了提高输出功率,输出整流二极管通常并联连接,变压器的副边漏电感作为二极管的均流电感.并分析了高压输入的大功率DC-DC逆变器的工作情况,同时给出了模拟结果和实验结果.

  14. Automatic System for the D.C. High Voltage Qualification of the Superconducting Electrical Circuits of the LHC Machine

    CERN Document Server

    Bozzini, D; Russenschuck, Stephan; Bednarek, M; Jurkiewicz, P; Kotarba, A; Ludwin, J; Olek, S

    2008-01-01

    A d.c. high voltage test system has been developed to verify automatically the insulation resistance of the powering circuits of the LHC. In the most complex case, up to 72 circuits share the same volume inside cryogenic lines. Each circuit can have an insulation fault versus any other circuit or versus ground. The system is able to connect up to 80 circuits and apply a voltage up to 2 kV D.C. The leakage current flowing through each circuit is measured within a range of 1 nA to 1.6 mA. The matrix of measurements allows characterizing the paths taken by the currents and locating weak points of the insulation between circuits. The system is composed of a D.C. voltage source and a data acquisition card. The card is able to measure with precision currents and voltages and to drive up to 5 high voltage switching modules offering 16 channels each. A LabVIEW application controls the system for an automatic and safe operation. This paper describes the hardware and software design, the testing methodology and the res...

  15. Isolated DC-DC Converter for Bidirectional Power Flow Controlling with Soft-Switching Feature and High Step-Up/Down Voltage Conversion

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2017-03-01

    Full Text Available In this paper, a novel isolated bidirectional DC-DC converter is proposed, which is able to accomplish high step-up/down voltage conversion. Therefore, it is suitable for hybrid electric vehicle, fuel cell vehicle, energy backup system, and grid-system applications. The proposed converter incorporates a coupled inductor to behave forward-and-flyback energy conversion for high voltage ratio and provide galvanic isolation. The energy stored in the leakage inductor of the coupled inductor can be recycled without the use of additional snubber mechanism or clamped circuit. No matter in step-up or step-down mode, all power switches can operate with soft switching. Moreover, there is a inherit feature that metal–oxide–semiconductor field-effect transistors (MOSFETs with smaller on-state resistance can be adopted because of lower voltage endurance at primary side. Operation principle, voltage ratio derivation, and inductor design are thoroughly described in this paper. In addition, a 1-kW prototype is implemented to validate the feasibility and correctness of the converter. Experimental results indicate that the peak efficiencies in step-up and step-down modes can be up to 95.4% and 93.6%, respectively.

  16. Design of high voltage DC-DC power supply based on LCS703HG%基于LCS703HG的高压DC-DC电源设计

    Institute of Scientific and Technical Information of China (English)

    韩冬林

    2012-01-01

    LCS703HG integrated LLC power stage IC was adopted to realize a DC-DC converter with 380 V DC input and 24 V DC/7 A output. According to characteristic and working principle of LCS703HG, the peripheral application circuit was designed, the key part of the circuit was analyzed, and the design was verified by test results.%采用集成了LLC谐振控制器的半桥功率芯片LCS703HG,实现了380 V DC高压输入,24 V DC/7 A输出的DC-DC电源设计.根据LCS703HG的特性和工作原理,设计了外围应用电路,分析了电路设计中的关键环节,并用测试结果验证了设计.

  17. An Improved Distributed Secondary Control Method for DC Microgrids With Enhanced Dynamic Current Sharing Performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Panbao; Lu, Xiaonan; Yang, Xu; Wang, Wei; Xu, Dianguo

    2016-09-01

    This paper proposes an improved distributed secondary control scheme for dc microgrids (MGs), aiming at overcoming the drawbacks of conventional droop control method. The proposed secondary control scheme can remove the dc voltage deviation and improve the current sharing accuracy by using voltage-shifting and slope-adjusting approaches simultaneously. Meanwhile, the average value of droop coefficients is calculated, and then it is controlled by an additional controller included in the distributed secondary control layer to ensure that each droop coefficient converges at a reasonable value. Hence, by adjusting the droop coefficient, each participating converter has equal output impedance, and the accurate proportional load current sharing can be achieved with different line resistances. Furthermore, the current sharing performance in steady and transient states can be enhanced by using the proposed method. The effectiveness of the proposed method is verified by detailed experimental tests based on a 3 × 1 kW prototype with three interface converters.

  18. DC Hierarchical Control System for Microgrid Applications

    OpenAIRE

    Lu, Xiaonan; Sun, Kai; Guerrero, Josep M.; Huang, Lipei

    2013-01-01

    In order to enhance the DC side performance of AC-DC hybrid microgrid,a DC hierarchical control system is proposed in this paper.To meet the requirement of DC load sharing between the parallel power interfaces,droop method is adopted.Meanwhile,DC voltage secondary control is employed to restore the deviation in the DC bus voltage.The hierarchical control system is composed of two levels.DC voltage and AC current controllers are achieved in the primary control level.

  19. Switching performance and efficiency investigation of GaN based DC-DC Buck converter for low voltage and high current applications

    Science.gov (United States)

    Alatawi, Khaled; Almasoudi, Fahad; Matin, Mohammad

    2016-09-01

    The Wide band-gap (WBG) materials "such as Silicon Carbide (SiC) and Gallium nitride (GaN)" based power switching devices provide higher performance capabilities compared to Si-based power switching devices. The wide band-gap materials based power switching devices outperform Si-based devices in many performance characteristics such as: low witching loss, low conduction loss, high switching frequencies, and high operation temperature. GaN based switching devices benefit a lot of applications such as: future electric vehicles and solar power inverters. In this paper, a DC-DC Buck converter based on GaN FET for low voltage and high current applications is designed and investigated. The converter is designed for stepping down a voltage of 48V to 12V with high switching frequency. The capability of the GaN FET based buck converter is studied and compared to equivalent SiC MOSFET and Si-based MOSFET buck converters. The analysis of switching losses and efficiency was performed to compare the performance capabilities of GaN FET, SiC MOSFET and Si-based MOSFET. The results showed that the overall switching losses of GaN FET are lower than that of SiC and Si-based power switching devices. Also, the performance capability of GaN devices with higher frequencies is studied. GaN devices with high frequencies will reduce the total size and the cost of the power converter. In Addition, the overall efficiency of the DC-DC Buck converter is higher with the GaN FET switching devices, which make it more suitable for low voltage and high current applications.

  20. Regulated dc-to-dc converter for voltage step-up or step-down with input-output isolation

    Science.gov (United States)

    Feng, S. Y.; Wilson, T. G. (Inventor)

    1973-01-01

    A closed loop regulated dc-to-dc converter employing an unregulated two winding inductive energy storage converter is provided by using a magnetically coupled multivibrator acting as duty cycle generator to drive the converter. The multivibrator is comprised of two transistor switches and a saturable transformer. The output of the converter is compared with a reference in a comparator which transmits a binary zero until the output exceeds the reference. When the output exceeds the reference, the binary output of the comparator drives transistor switches to turn the multivibrator off. The multivibrator is unbalanced so that a predetermined transistor will always turn on first when the binary feedback signal becomes zero.

  1. Analysis of a dc SQUID readout scheme with voltage feedback circuit and low-noise preamplifier

    Science.gov (United States)

    Zeng, Jia; Zhang, Yi; Schmelz, Matthias; Mück, Michael; Krause, Hans-Joachim; Braginski, Alex I.; Lee, Yong-Ho; Stolz, Ronny; Kong, Xiangyan; Xie, Xiaoming; Meyer, Hans-Georg; Offenhäusser, Andreas; Jiang, Mianheng

    2014-08-01

    We analyzed the dc SQUID with voltage feedback circuit (VFC) and a low-noise room-temperature preamplifier to evaluate the feasibility of a low-noise SQUID direct-coupled readout scheme (DRS), possibly eliminating the need for a two-stage scheme employing a SQUID preamplifier. The passive VFC, connected in parallel to the SQUID, consists of a resistor Rs in series with an inductor L s. This inductor is coupled to the SQUID by a mutual inductance Ms. The purpose of the VFC is to increase the SQUID’s flux-to-voltage transfer coefficient ∂V/∂Φ, thus reducing the preamplifier noise contribution δΦpreamp. However, at the same time, VFC introduces the thermal noise of Rs, δΦR, which may not be negligible. Generally, the noise of the readout scheme, δΦreadout, may thus include both δΦpreamp and δΦR, i.e., δΦreadout2 = δΦpreamp2 + δΦR2. To characterize the SQUID operation with VFC we introduced two dimensionless parameters, r = Rs/Rd and Δ = (M s/Mdyn) - (Rs/R d), where Rd and Mdyn = 1/(∂i/∂Φ) are dynamic properties of the SQUID itself. For assumed intrinsic SQUID parameters, we then numerically analyzed the dependence of δΦreadout noise components on r and Δ to determine their suitable ranges and the minimum of δΦreadout. To verify our analysis, we experimentally characterized, in liquid helium, three niobium SQUIDs with VFC, having suitably chosen r and Δ. The measured SQUID system flux noise was on the order of 1 μΦ0/√Hz, comparable to the intrinsic noise of the SQUID itself. The deduced equivalent voltage noise was comparable to that of a SQUID preamplifier in the two-stage readout. Simple single-stage ultra-low-noise SQUID DRS readout was thus demonstrated.

  2. Proposal of indexes for fast voltage stability evaluation of ac/dc transmission systems

    Directory of Open Access Journals (Sweden)

    Jorge Wilson González

    2011-01-01

    Full Text Available En este artículo se desarrolla un análisis de estabilidad de tensión de sistemas ca/cd empleando indicadores estáticos y modales. Se propone un tratamiento novedoso para indicadores de estabilidad de tensión, con el fin de obtener una mayor información sobre los requerimientos en redes de variadas fortalezas, en términos de la estabilidad de tensión. El nuevo tratamiento se ofrece como un medio para prevenir potenciales problemas en redes de transmisión de corriente directa, High Voltage dc Transmission Systems (HVdc, conectados a nodos débiles. Los indicadores son convertidos a por unidad y comparados en diferentes relaciones de corto circuito, Short Circuit Ratios (SCR, en una red modificada tipo IEEE de 14 barras, la cual posee un sistema HVdc conectado en su barra más débil. Los alcances pueden servir tanto para planeamiento como para monitoreo en tiempo real de la estabilidad de tensión en sistemas eléctricos de potencia incluyendo nodos ca/cd.

  3. Over-voltage protection system and method

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Song; Dong, Dong; Lai, Rixin

    2017-05-02

    An over-voltage protection system includes an electronic valve connected across two terminals of a circuit and an over-voltage detection circuit connected across one of the plurality of semiconductor devices for detecting an over-voltage across the circuit. The electronic valve includes a plurality of semiconductor devices connected in series. The over-voltage detection circuit includes a voltage divider circuit connected to a break-over diode in a way to provide a representative low voltage to the break-over diode and an optocoupler configured to receive a current from the break-over diode when the representative low voltage exceeds a threshold voltage of the break-over diode indicating an over-voltage condition. The representative low voltage provided to the break-over diode represents a voltage across the one semiconductor device. A plurality of self-powered gate drive circuits are connected to the plurality of semiconductor devices, wherein the plurality of self-powered gate drive circuits receive over-voltage triggering pulses from the optocoupler during the over-voltage condition and switch on the plurality of semiconductor devices to bypass the circuit.

  4. A Grid Voltage Measurement Method for Wind Power Systems during Grid Fault Conditions

    Directory of Open Access Journals (Sweden)

    Cheol-Hee Yoo

    2014-11-01

    Full Text Available Grid codes in many countries require low-voltage ride-through (LVRT capability to maintain power system stability and reliability during grid fault conditions. To meet the LVRT requirement, wind power systems must stay connected to the grid and also supply reactive currents to the grid to support the recovery from fault voltages. This paper presents a new fault detection method and inverter control scheme to improve the LVRT capability for full-scale permanent magnet synchronous generator (PMSG wind power systems. Fast fault detection can help the wind power systems maintain the DC-link voltage in a safe region. The proposed fault detection method is based on on-line adaptive parameter estimation. The performance of the proposed method is verified in comparison to the conventional voltage measurement method defined in the IEC 61400-21 standard.

  5. Development of a New Cascade Voltage-Doubler for Voltage Multiplication

    OpenAIRE

    Arash Toudeshki; Norman Mariun; Hashim Hizam; Noor Izzri Abdul Wahab

    2014-01-01

    For more than eight decades, cascade voltage-doubler circuits are used as a method to produce DC output voltage higher than the input voltage. In this paper, the topological developments of cascade voltage-doublers are reviewed. A new circuit configuration for cascade voltage-doubler is presented. This circuit can produce a higher value of the DC output voltage and better output quality compared to the conventional cascade voltage-doubler circuits, with the same number of stages.

  6. Method and system for a gas tube switch-based voltage source high voltage direct current transmission system

    Energy Technology Data Exchange (ETDEWEB)

    She, Xu; Chokhawala, Rahul Shantilal; Zhou, Rui; Zhang, Di; Sommerer, Timothy John; Bray, James William

    2016-12-13

    A voltage source converter based high-voltage direct-current (HVDC) transmission system includes a voltage source converter (VSC)-based power converter channel. The VSC-based power converter channel includes an AC-DC converter and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and a DC-AC inverter include at least one gas tube switching device coupled in electrical anti-parallel with a respective gas tube diode. The VSC-based power converter channel includes a commutating circuit communicatively coupled to one or more of the at least one gas tube switching devices. The commutating circuit is configured to "switch on" a respective one of the one or more gas tube switching devices during a first portion of an operational cycle and "switch off" the respective one of the one or more gas tube switching devices during a second portion of the operational cycle.

  7. Optimal Design of DC Fast-Charging Stations for EVs in Low Voltage Grids

    DEFF Research Database (Denmark)

    Gjelaj, Marjan; Træholt, Chresten; Hashemi Toghroljerdi, Seyedmostafa

    2017-01-01

    the design of a new DCFCS for EVs coupled with a local Battery Energy Storage (BES). DCFCS is equipped with a bidirectional AC/DC converter for feeding power back to the grid, two lithium batteries and a DC/DC converter. This paper proposes an optimal size of the BES to reduce the negative impacts...

  8. DC-Link Voltage Coordinated-Proportional Control for Cascaded Converter With Zero Steady-State Error and Reduced System Type

    DEFF Research Database (Denmark)

    Tian, Yanjun; Loh, Poh Chiang; Deng, Fujin

    2016-01-01

    Cascaded converter is formed by connecting two subconverters together, sharing a common intermediate dc-link voltage. Regulation of this dc-link voltage is frequently realized with a proportional-integral (PI) controller, whose high gain at dc helps to force a zero steady-state tracking error...... a coordinated control scheme for the cascaded converter, which uses only a proportional dc-link voltage regulator. The resulting converter is thus dynamically faster, and when compared with the conventional PI-controlled converter, it is less affected by impedance interaction between its two subconverters....... Such precise tracking is, however, at the expense of increasing the system type, caused by the extra pole at the origin introduced by the PI controller. The overall system may, hence, be tougher to control. To reduce the system type while preserving precise dc-link voltage tracking, this paper proposes...

  9. Capacitance Estimation Algorithm based on DC-Link Voltage Harmonics Using ANN in Three-Phase Motor Drive Systems

    DEFF Research Database (Denmark)

    Soliman, Hammam Abdelaal Hammam; Davari, Pooya; Wang, Huai

    2017-01-01

    monitoring methodologies are rarely adopted by industry due to shortcomings such as, low estimation accuracy, extra hardware, and increased cost. Therefore, development of new condition monitoring methodologies that are based on advanced software and requires no extra hardware could be more attractive......-link voltage are used as training data to the Artificial Neural Network. Fast Fourier Transform (FFT) of the dc-link voltage is analysed in order to study the impact of capacitance variation on the harmonics order. Laboratory experiments are conducted to validate the proposed methodology and the error analysis...

  10. DC-Link Capacitor Voltage Regulation for Three-Phase Three-Level Inverter-Based Shunt Active Power Filter with Inverted Error Deviation Control

    Directory of Open Access Journals (Sweden)

    Yap Hoon

    2016-07-01

    Full Text Available A new control technique known as inverted error deviation (IED control is incorporated into the main DC-link capacitor voltage regulation algorithm of a three-level neutral-point diode clamped (NPC inverter-based shunt active power filter (SAPF to enhance its performance in overall DC-link voltage regulation so as to improve its harmonics mitigation performances. In the SAPF controller, DC-link capacitor voltage regulation algorithms with either the proportional-integral (PI or fuzzy logic control (FLC technique have played a significant role in maintaining a constant DC-link voltage across the DC-link capacitors. However, both techniques are mostly operated based on a direct voltage error manipulation approach which is insufficient to address the severe DC-link voltage deviation that occurs during dynamic-state conditions. As a result, the conventional algorithms perform poorly with large overshoot, undershoot, and slow response time. Therefore, the IED control technique is proposed to precisely address the DC-link voltage deviation. To validate effectiveness and feasibility of the proposed algorithm, simulation work in MATLAB-Simulink and experimental implementation utilizing a TMS320F28335 Digital Signal Processor (DSP are performed. Moreover, conventional algorithms with PI and FLC techniques are tested too for comparison purposes. Both simulation and experimental results are presented, confirming the improvement achieved by the proposed algorithm in terms of accuracy and dynamic response in comparison to the conventional algorithms.

  11. Dynamic Characteristic Analysis of Linear DC Motor by 3D EMCN Considering Input Voltage

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Kyung Ho; Yeom, Sang Bu [Changwon National University, Changwon(Korea); Hong, JUNG Pyo; Hur Jin; Kang Do Hyunc [Hanyang University(Seoul Campus), Seoul(Korea)

    2002-02-01

    In order to design the Linear DC Motor (LDM) With improved characteristics, transient and steady state analysis are required. Furthermore, 3D analysis is also needed to analyze the precise characteristics like thrust, time harmonics. This paper deals with the transient and dynamic characteristic analysis if LDM by coupling of external circuit and motion equation using 3D Equivalent Magnetic Circuit Network Method (EMCN). For the three dimensional analysis of electric machine, EMCN is very effective method that ensures high accuracy similar to FEM and short computation time. Also, The modeling by EMCN easily allows the mover to move with respect to the Sartre at each time Also, and the spatial moving step is determined by the solution of the mechanical motion equation and the computed electromagnetic thrust. The results are compared with experimental ones to clarify the usefulness and verify the accuracy of the proposed method. (author). 11 refs., 20 figs., 2 tabs.

  12. Sample-Data Modeling of a Zero Voltage Transition DC-DC Converter for On-Board Battery Charger in EV

    Directory of Open Access Journals (Sweden)

    Teresa R. Granados-Luna

    2014-01-01

    Full Text Available Battery charger is a key device in electric and hybrid electric vehicles. On-board and off-board topologies are available in the market. Lightweight, small, high performance, and simple control are desired characteristics for on-board chargers. Moreover, isolated single-phase topologies are the most common system in Level 1 battery charger topologies. Following this trend, this paper proposes a sampled-data modelling strategy of a zero voltage transition (ZVT DC-DC converter for an on-board battery charger. A piece-wise linear analysis of the converter is the basis of the technique presented such that a large-signal model and, therefore, a small-signal model of the converter are derived. Numerical and simulation results of a 250 W test rig validate the model.

  13. Analysis and design of a high-efficiency zero-voltage-switching step-up DC–DC converter

    Indian Academy of Sciences (India)

    Jae-Won Yang; Hyun-Lark Do

    2013-08-01

    A high-efficiency zero-voltage-switching (ZVS) step-up DC–DC converter is proposed. The proposed ZVS DC–DC step-up converter has fixed switching frequency, simple control, and high efficiency. All power switches can operate with ZVS. The output diodes are under zero-current-switching (ZCS) during turn-off. Due to soft-switching operation of the power switches and output diodes, the proposed ZVS DC–DC converter shows high efficiency. Steady-state analysis of the converter is presented to determine the circuit parameters. A laboratory prototype of the proposed converter is developed, and its experimental results are presented for validation.

  14. Charge and fluence lifetime measurements of a dc high voltage GaAs photogun at high average current

    Energy Technology Data Exchange (ETDEWEB)

    J. Grames, R. Suleiman, P.A. Adderley, J. Clark, J. Hansknecht, D. Machie, M. Poelker, M.L. Stutzman

    2011-04-01

    GaAs-based dc high voltage photoguns used at accelerators with extensive user programs must exhibit long photocathode operating lifetime. Achieving this goal represents a significant challenge for proposed high average current facilities that must operate at tens of milliamperes or more. This paper describes techniques to maintain good vacuum while delivering beam, and techniques that minimize the ill effects of ion bombardment, the dominant mechanism that reduces photocathode yield of a GaAs-based dc high voltage photogun. Experimental results presented here demonstrate enhanced lifetime at high beam currents by: (a) operating with the drive laser beam positioned away from the electrostatic center of the photocathode, (b) limiting the photocathode active area to eliminate photoemission from regions of the photocathode that do not support efficient beam delivery, (c) using a large drive laser beam to distribute ion damage over a larger area, and (d) by applying a relatively low bias voltage to the anode to repel ions created within the downstream beam line. A combination of these techniques provided the best total charge extracted lifetimes in excess of 1000 C at dc beam currents up to 9.5 mA, using green light illumination of bulk GaAs inside a 100 kV photogun.

  15. Plasma surface treatment to improve surface charge accumulation and dissipation of epoxy resin exposed to DC and nanosecond-pulse voltages

    Science.gov (United States)

    Zhang, Cheng; Lin, Haofan; Zhang, Shuai; Xie, Qin; Ren, Chengyan; Shao, Tao

    2017-10-01

    In this paper, deposition by non-thermal plasma is used as a surface modification technique to change the surface characteristics of epoxy resin exposed to DC and nanosecond-pulse voltages. The corresponding surface characteristics in both cases of DC and nanosecond-pulse voltages before and after the modification are compared and investigated. The measurement of the surface potential provides the surface charge distribution, which is used to show the accumulation and dissipation process of the surface charges. Morphology observations, chemical composition and electrical parameters measurements are used to evaluate the treatment effects. The experimental results show that, before the plasma treatment, the accumulated surface charges in the case of the DC voltage are more than that in the case of the nanosecond-pulse voltage. Moreover, the decay rate of the surface charges for the DC voltage is higher than that for the nanosecond-pulse voltage. However, the decay rate is no more than 41% after 1800 s for both types of voltages. After the plasma treatment, the maximum surface potentials decrease to 57.33% and 32.57% of their values before treatment for the DC and nanosecond-pulse voltages, respectively, indicating a decrease in the accumulated surface charges. The decay rate exceeds 90% for both types of voltages. These changes are mainly attributed to a change in the surface nanostructure, an increase in conductivity, and a decrease in the depth of energy level.

  16. Nanosecond pulsed electric fields (nsPEFs) low cost generator design using power MOSFET and Cockcroft-Walton multiplier circuit as high voltage DC source

    Science.gov (United States)

    Sulaeman, M. Y.; Widita, R.

    2014-09-01

    Purpose: Non-ionizing radiation therapy for cancer using pulsed electric field with high intensity field has become an interesting field new research topic. A new method using nanosecond pulsed electric fields (nsPEFs) offers a novel means to treat cancer. Not like the conventional electroporation, nsPEFs able to create nanopores in all membranes of the cell, including membrane in cell organelles, like mitochondria and nucleus. NsPEFs will promote cell death in several cell types, including cancer cell by apoptosis mechanism. NsPEFs will use pulse with intensity of electric field higher than conventional electroporation, between 20-100 kV/cm and with shorter duration of pulse than conventional electroporation. NsPEFs requires a generator to produce high voltage pulse and to achieve high intensity electric field with proper pulse width. However, manufacturing cost for creating generator that generates a high voltage with short duration for nsPEFs purposes is highly expensive. Hence, the aim of this research is to obtain the low cost generator design that is able to produce a high voltage pulse with nanosecond width and will be used for nsPEFs purposes. Method: Cockcroft-Walton multiplier circuit will boost the input of 220 volt AC into high voltage DC around 1500 volt and it will be combined by a series of power MOSFET as a fast switch to obtain a high voltage with nanosecond pulse width. The motivation using Cockcroft-Walton multiplier is to acquire a low-cost high voltage DC generator; it will use capacitors and diodes arranged like a step. Power MOSFET connected in series is used as voltage divider to share the high voltage in order not to damage them. Results: This design is expected to acquire a low-cost generator that can achieve the high voltage pulse in amount of -1.5 kV with falltime 3 ns and risetime 15 ns into a 50Ω load that will be used for nsPEFs purposes. Further detailed on the circuit design will be explained at presentation.

  17. Nanosecond pulsed electric fields (nsPEFs) low cost generator design using power MOSFET and Cockcroft-Walton multiplier circuit as high voltage DC source

    Energy Technology Data Exchange (ETDEWEB)

    Sulaeman, M. Y.; Widita, R. [Department of Physics, Nuclear Physics and Biophysics Research Division, Faculty of Mathematics and Natural Science, Institut Teknologi Bandung, Bandung (Indonesia)

    2014-09-30

    Purpose: Non-ionizing radiation therapy for cancer using pulsed electric field with high intensity field has become an interesting field new research topic. A new method using nanosecond pulsed electric fields (nsPEFs) offers a novel means to treat cancer. Not like the conventional electroporation, nsPEFs able to create nanopores in all membranes of the cell, including membrane in cell organelles, like mitochondria and nucleus. NsPEFs will promote cell death in several cell types, including cancer cell by apoptosis mechanism. NsPEFs will use pulse with intensity of electric field higher than conventional electroporation, between 20–100 kV/cm and with shorter duration of pulse than conventional electroporation. NsPEFs requires a generator to produce high voltage pulse and to achieve high intensity electric field with proper pulse width. However, manufacturing cost for creating generator that generates a high voltage with short duration for nsPEFs purposes is highly expensive. Hence, the aim of this research is to obtain the low cost generator design that is able to produce a high voltage pulse with nanosecond width and will be used for nsPEFs purposes. Method: Cockcroft-Walton multiplier circuit will boost the input of 220 volt AC into high voltage DC around 1500 volt and it will be combined by a series of power MOSFET as a fast switch to obtain a high voltage with nanosecond pulse width. The motivation using Cockcroft-Walton multiplier is to acquire a low-cost high voltage DC generator; it will use capacitors and diodes arranged like a step. Power MOSFET connected in series is used as voltage divider to share the high voltage in order not to damage them. Results: This design is expected to acquire a low-cost generator that can achieve the high voltage pulse in amount of −1.5 kV with falltime 3 ns and risetime 15 ns into a 50Ω load that will be used for nsPEFs purposes. Further detailed on the circuit design will be explained at presentation.

  18. Dynamic pattern formation of liquid crystals using binary self-assembled monolayers on an ITO surface under DC voltage.

    Science.gov (United States)

    Ishida, Takao; Oyama, Makiko; Terada, Kei-ichi; Haga, Masa-aki

    2014-12-07

    There have been numerous studies of liquid crystal (LC) convection using sandwich-type LC cells under AC voltage. In contrast to previous LC convection studies under AC voltage, we propose the use of a binary self-assembled monolayer (SAM) with a redox-active Ru complex and insulating octadecyl phosphonic acid (C18) molecules on an indium tin oxide (ITO) surface as the electrode of sandwich-type LC cells under DC bias voltage. This is because the functionalized molecules immobilized on the ITO surface are expected to control the LC orientation and electrical conduction of LC cells, under an exact DC bias voltage. We successfully achieved LC pattern formation using ITO electrodes with binary SAMs in LC cells. Moreover, we confirmed that the LC pattern size was increased by increasing the coverage of the Ru complex in binary SAMs. We consider that a combination of three factors, electrical conduction change, controlling of LC orientation in the initial stage and redox-activity of the Ru-complex, is the reason for LC convection although we cannot fully explain the distribution of these three factors. We believe that our LC pattern formation is promising for new type devices e.g., artificial compound eyes using the LC device technology.

  19. Characteristic Analysis of Partial Discharges and Dissolved Gases Generated Cavityin Oil-paper Insulation Under AC-DC Combined Voltages

    Institute of Scientific and Technical Information of China (English)

    HE Zhiman; LI Jian; BAO Lianwei; JIANG Tianyan; WANG Youyuan

    2012-01-01

    Oil-paper insulation is used within most of high voltage direct current(HVDC) converter transformers.Partial discharge(PD) in oil-paper insulation is a major reason for the development of internal faults in HVDC converter transformer,while PDs in oil-paper insulation mainly occur in terms of gas cavity discharges.There are few study results on the development characteristics of partial discharges in oil-paper insulation and dissolved gases in oils of HVDC converter transformers.Based on a gas cavity discharge model of oil-paper insulation,the present study investigates the development characteristics of partial discharges under AC-DC combined voltages and emphatically examines the variation characteristics of dissolved gases in the discharge development process.Experiment and analysis results show that the characteristics of partial discharges and dissolved gases in oils under AC-DC combined voltages are appreciably different with those under AC voltage.These results provide theoretical support for further research on partial discharges and on dissolved gases of other internal insulating defects and are helpful for the fault diagnosis of HVDC converter transformers.

  20. Evaluation results on the effectiveness of the corrosion protection system for underground pipelines, using the DC-voltage gradient technique

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Antonio Carlos [Petroquimica Uniao S.A., Santo Andre, SP (Brazil)

    2003-07-01

    A pipeline of diameter 6'' with 17.694 km of extension was evaluated how much to the integrity of its external covering and the effectiveness of the system of cathodic protection, using the method DC-Voltage Gradient. The Cathodic Protection in this pipeline is made by seven rectifiers. The gotten data indicate that the potential pipe-ground registered in some check points to the long one of the pipeline is extremely negative, what has led to a super protection of the pipeline for the CP. This if explains for the great proximity between the anodes and the pipeline. For km had been identified 917 failures with a mean density of 50,1 per Km. Beyond the analysis of the data, this work includes conclusions and recommendations detailed for the repairs of the covering of the pipeline and for improvement of the effectiveness of the CP. One sends regards to a combination of repairs in the covering and reevaluation of the CP, in way to improve the protection level and to assure the reduction of the risk of external corrosion. (author)

  1. Dual-Input Soft-Switched DC-DC Converter with Isolated Current-Fed Half-Bridge and Voltage-Fed Full-Bridge for Fuel Cell or Photovoltaic Systems

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

    2013-01-01

    This paper introduces a new zero-voltage-switching (ZVS) isolated DC-DC converter with two input ports which can be utilized in hybrid energy systems, for instance, in a fuel cell and super-capacitor system. By fully using two high frequency transformers, the proposed converter can effectively...

  2. Combined Discrete Space Voltage Vector with Direct Torque Control for Bearingless Brushless DC Motor and Closed-Loop Suspended Force Control

    Directory of Open Access Journals (Sweden)

    Weiran Wang

    2013-06-01

    Full Text Available In order to improve the performance of bearingless brushless DC motor, a closed-loop suspended force controller combining the discrete space voltage vector modulation is applied and the direct torque control is presented in this paper. Firstly, we increase the number of the control vector to reduce the torque ripple. Then, the suspending equation is constructed which is spired by the direct torque control algorithm. As a result, the closed-loop suspended force controller is built. The simulated and experimental results evaluate the performance of the proposed method. The more advantage is that the proposed algorithm can achieve the fast torque response, reduce the torque ripple, and follow ideal stator flux track. Furthermore, the motor which implants the closed-loop suspended force controller cannot onlyobtain the dynamic response rapidly and displacement control accurately, but also has the characteristics of bearingless brushless DC motor (such as simple structure, high energy efficiency, small volume and low failure rate.

  3. Analysis of voltage modulation based active damping techniques for small DC-link drive system

    DEFF Research Database (Denmark)

    Wang, Dong; Lu, Kaiyuan; Rasmussen, Peter Omand;

    2015-01-01

    Small DC-link drive system, built with film capacitor in the DC link, may have the advantages of longer lifetime and the possibility to achieve a more compact design of capacitor bank at medium and high power rates. However, it exhibits instability problem, especially when it is fed by a soft grid...

  4. Isolated PWM DC-AC SICAM with an active capacitive voltage clamp[Pulse Density Modulated; Pulse Width Modulation

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.

    2004-03-15

    In this report an isolated PWM DC-AC SICAM with an active capacitive voltage clamp is presented. AC-DC power supply is implemented in its simplest form: diode rectifier followed by a medium-size charge-storage capacitors and possibly with an EMC filter on the mains entrance. Isolation from the AC mains is achieved using a high frequency (HF) transformer, whose voltages are not audio-modulated. The latter simplifies the design and is expected to have many advantages over the approach where the transformer voltages are modulated in regards to the audio signal reference. Input stage is built as a DC-AC inverter (push-pull, half-bridge or a full-bridge) and operated with 50% duty cycle, with all the challenges to avoid transformer saturation and obtain symmetrical operation. On the secondary side the output section is implemented as rectifier+inverter AC-AC stage, i.e. a true bidirectional bridge, which operation is aimed towards amplification of the audio signal. In order to solve the problem with the commutation of the load current, a dead time between the incoming and outgoing bidirectional switch is implemented, while a capacitive voltage clamp is used to keep the induced overvoltage to reasonable levels. The energy stored in the clamping capacitor is not wasted as in the dissipative clamps, but is rather transferred back to the primary side for further processing using an auxiliary isolated single-switch converter, i.e. an active clamping technique is used. (au)

  5. Thermal conductivity measurement of thin films by a dc method.

    Science.gov (United States)

    Yang, Junyou; Zhang, Jiansheng; Zhang, Hui; Zhu, Yunfeng

    2010-11-01

    A dc method, which needs no complex numerical calculation and expensive hardware configuration, was developed to measure the cross-plane thermal conductivity of thin films in this paper. Two parallel metallic heaters, which were deposited on different parts of the sample, serve simultaneously as the heaters and temperature sensors during the measurement. A direct current was flowed through the same two metallic strips to heat the thin-film sample. The heating power and the heater's temperature were obtained by a data acquisition device, and the thermal conductivity of thin film was calculated. To verify the validity of the dc method, several SiO(2) films with different thicknesses were deposited on Si wafers, respectively, and their thermal conductivities were measured by both the dc method and 3ω method. The results of two methods are in good agreement within an acceptable error, and they are also inconsistent with some of previously published data.

  6. A Novel High-Frequency Voltage Standing-Wave Ratio-Based Grounding Electrode Line Fault Supervision in Ultra-High Voltage DC Transmission Systems

    Directory of Open Access Journals (Sweden)

    Yufei Teng

    2017-03-01

    Full Text Available In order to improve the fault monitoring performance of grounding electrode lines in ultra-high voltage DC (UHVDC transmission systems, a novel fault monitoring approach based on the high-frequency voltage standing-wave ratio (VSWR is proposed in this paper. The VSWR is defined considering a lossless transmission line, and the characteristics of the VSWR under different conditions are analyzed. It is shown that the VSWR equals 1 when the terminal resistance completely matches the characteristic impedance of the line, and when a short circuit fault occurs on the grounding electrode line, the VSWR will be greater than 1. The VSWR will approach positive infinity under metallic earth fault conditions, whereas the VSWR in non-metallic earth faults will be smaller. Based on these analytical results, a fault supervision criterion is formulated. The effectiveness of the proposed VSWR-based fault supervision technique is verified with a typical UHVDC project established in Power Systems Computer Aided Design/Electromagnetic Transients including DC(PSCAD/EMTDC. Simulation results indicate that the proposed strategy can reliably identify the grounding electrode line fault and has strong anti-fault resistance capability.

  7. Comparison of three-phase three-level voltage source inverter with intermediate dc–dc boost converter and quasi-Z-source inverter

    DEFF Research Database (Denmark)

    Panfilov, Dmitry; Husev, Oleksandr; Blaabjerg, Frede

    2016-01-01

    This study compares a three-phase three-level voltage source inverter with an intermediate dc-dc boost converter and a quasi-Z-source inverter in terms of passive elements values and dimensions, semiconductor stresses, and overall efficiency. A comparative analysis was conducted with relative par...

  8. Overmodulation of n-level three-leg DC-AC diode-clamped converters with comprehensive capacitor voltage balance

    DEFF Research Database (Denmark)

    Busquets-Monge, S.; Maheshwari, Ram Krishan; Munk-Nielsen, Stig

    2013-01-01

    This paper presents a novel PWM strategy for nlevel three-leg semiconductor-clamped dc-ac converters in the overmodulation region, with dc-link capacitor voltage balance in every switching cycle. The strategy is based on the virtual-vector concept. Suitable reference vector trajectories are selec...

  9. Development of a portable low-cost and low-noise DC/DC high voltage switching power supply for optics application

    Energy Technology Data Exchange (ETDEWEB)

    Hung, K.-Y.; Chen, Y.-C. [Mingchi Univ. of Technology, Taishan, Taipei, Taiwan (China). Inst. of Mechanical and Electrical Engineering, Dept. of Mechanical Engineering

    2007-07-01

    A commercial power supply is bulky in size, very expensive and produces extremely noisy voltage, carrying approximately 45 mV of surge at the maximum. An avalanche photo diode (APD) is used to detect weak fluorescent signals, making it easy to generate extremely intensified noise, and degrading the S/N ratio. In order to resolve this problem, this paper discussed the development of a portable high voltage transformer-free direct current (DC) drive circuit module with low cost, noise, and power for photoelectric components. The module can be used on photoelectric components requiring high reverse voltage, such as APDs, piezo transformers, vacuum florescent displays, and micro electric machines. The low-noise module effectively reduced the thermal noise of photodiodes, leading to an improvement in the S/N ratio of photoelectric components by approximately 37 per cent. The module was described in detail. Several graphs and tables were presented, including a comparison between various types of converters; the design structure of the control unit circuit; and diagram of converted circuit diagram. It was concluded that the module was efficient, compact, and portable and designed with a transformer-free circuitry. In addition, the power supply module was successfully developed and would be much more feasible to use in developing portable products, such as digital cameras, and other advanced products. 1 tab., 4 figs.

  10. 线性直流稳压电源实验分析%Experimental Analysis of Linear DC Stabilized Voltage Power Supply

    Institute of Scientific and Technical Information of China (English)

    唐红

    2012-01-01

    Stabilized voltage power supply is a important chapter of analog electronics technology course. In the course of teaching practice activities about linear DC stabilized voltage power supply, some phenomenon that test data is not accurate and components are burnt out often turn up. As a result, it is important to master circuit philosophy and test method of stabilized voltage power supply. Students can be familiar with stabilized vohage power supply which is made up of single phase bridge rectifier, capacitor filter and integration of the three terminal regulator and the method to test each technical indication of stabilized voltage power supply.%稳压电源是模拟电子技术课程中重要的章节,在线性直流稳压电源教学实验活动中,常会出现测试数据不准、烧坏元器件等现象,因此掌握稳压电源的电路原理及测试方法极为重要。通过线性稳压电源实验,使学生熟悉由单相桥式整流、电容滤波和集成三端稳压器组成的直流稳压电源;熟悉稳压电源各项技术指标的测量方法。

  11. Research of DC Voltage Ripple of Single-phase AFE%单相有源前端直流电压脉动研究

    Institute of Scientific and Technical Information of China (English)

    杨艳; 朱荣伍

    2011-01-01

    单相PWM整流器作为串联H桥多电平变频器的有源前端,可以满足矿井提升机对电气传动系统能量双向流动能力的要求,但是其输出2次脉动电压使得网侧电流存在3次谐波.针对上述问题,提出了一种稳态误差前馈补偿的方法,即将输出直流电压的二倍频正弦误差信号补偿至直流电压给定信号,以减小电压脉动对电网电流畸变的影响.仿真及硬件实验验证了该方法的有效性.%To take single-phase PWM rectifier as AFE of cascaded H-bridge multi-level frequency converter can satisfy requirement that electric drive system of coal mine hoist must have capacity of bidirectional energy flowing, but there are third harmonic in its AC-side current because of the second ripple of output voltage. To slove the problem, a method of steady-state error feed-forward compensation was put forward, namely frequency-doubled sinusoidal error signal of output DC voltage is compensated to set signal of DC voltage in order to reduce influence of voltage ripple on distorted current of power grid. The results of simulation and hardware experiment showed that the method is effective.

  12. Fault Diagnosis and Fault-tolerant Control of Modular Multi-level Converter High-voltage DC System: A Review

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Wang, Chao;

    2016-01-01

    Modular Multilevel Converter based High Voltage Direct Current (MMC-HVDC) configuration is a promising solution for the efficient grid integration and bulky power transmission over long distance. However, the large number of series connected identical modules in MMC may increase the probability...... strategies of MMC-HVDC systems for the most common faults happened in MMC-HVDC systems covering MMC faults, DC side faults as well as AC side faults. An important part of this paper is devoted to a discussion of the vulnerable spots as well as failure mechanism of the MMC-HVDC system covering switching...... device fault, DC line faults as well as AC grid faults. Special attention is given to the comparison of the corresponding fault diagnosis and fault-tolerant control approaches. Further, focus is dedicated to control/protection strategies and topologies with fault ride-though capability for MMC...

  13. Distributed Nonlinear Control with Event-Triggered Communication to Achieve Current-Sharing and Voltage Regulation in DC Microgrids

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Guerrero, Josep M.

    2017-01-01

    A distributed nonlinear controller is presented to achieve both accurate current-sharing and voltage regulation simultaneously in dc microgrids considering different line impedances’ effects among converters. Then, an improved event-triggered principle for the controller is introduced through...... combining the state-dependent tolerance with a nonnegative offset. In order to design the event-triggered principle and guarantee the global stability, a generalized dc microgrid model is proposed and proven to be positive definite, based on which Lyapunov-based approach is applied. Furthermore, considering...... the effects from constant power loads, the damping performance of proposed controller is further improved and compared with the traditional V-I droop controller. The proposed event-triggered-based communication strategy can considerably reduce the communication traffic and significantly relax the requirement...

  14. Calculation Method for Normal Inducedlongitudinal Voltage on Pilot Cable

    Directory of Open Access Journals (Sweden)

    Abdelaziz B.M. Kamel,

    2014-09-01

    Full Text Available In this paper a full study and detailed calculations of the induced voltage in pilot cables are carried out. First an introduction showing the importance of the induced voltage and its effect in pilot cables. The first calculation method Flat Formation. The second calculation method Trefoil Formation. Then the results obtained for both methods and compared. Finally a conclusion is conduct.

  15. Multi-Purpose Low Voltage Dual Output DC-DC Converter For 100V Power Bus Telecom Platform

    Science.gov (United States)

    Galiana, D.; Mollard, J. M.

    2011-10-01

    The decreasing supply voltages of digital electronic and high speed ADC (Analog to Digital Converter) and DAC (Digital to Analog Converter) require flexible and high current secondary power distribution system. In the frame of the Inmarsat I-XL program, a 12 kW geomobile SatCom satellite, with 100 V regulated power bus, a multi purpose dual output converter was developed for the payload processor as a building block. After a short introduction on the main performance requirements, the baseline architecture is presented. The main drivers of the architecture are reliability, adjustability, radiation tolerant and single event free, volume and mass. The combination of all these constraints highlights the need of significant breakthrough in various domains. Many research results related to packaging and power electronic topics are brought up. These results directly drive the adopted solution presented in the next step followed by a description of the integration of the defined building block in the Inmarsat I-XL payload IP (Integrated Processor). Finally, the main electrical performances such as output ripple and spikes, load step transient and stability are summarized.

  16. A control method for voltage balancing in modular multilevel converters

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2014-01-01

    The modular multilevel converter (MMC) is attractive for medium- or high-power applications because of the advantages of its high modularity, availability, and high power quality. The voltage balancing of the floating capacitors in the cascaded submodules of the MMC is a key issue. In this paper......, a voltage-balancing control method is proposed. This method uses the phase-shifted carrier-based pulsewidth modulation scheme to control high-frequency current components for capacitor voltage balancing in the MMC without measuring the arm currents. Simulations and experimental studies of the MMC were...... conducted, and the results confirm the effectiveness of the proposed capacitor voltage-balancing control method....

  17. THE ANALYSIS OF STEADY VOLTAGE ON THE ACCESSION OF DC TRACTION SUBSTATIONS

    Directory of Open Access Journals (Sweden)

    V. H. Sychenko

    2009-09-01

    Full Text Available Research results of voltage modes at traction substation buses in primary, regional and traction network are presented in the article. Numeric characteristics of probability density distributions are obtained. Autocorrelation functions of positive and negative sequence voltages are analyzed.

  18. Fault Diagnosis and Fault-tolerant Control of Modular Multi-level Converter High-voltage DC System

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Wang, Chao

    2016-01-01

    Modular Multilevel Converter based High Voltage Direct Current (MMC-HVDC) configuration is a promising solution for the efficient grid integration and bulky power transmission over long distance. However, the large number of series connected identical modules in MMC may increase the probability...... strategies of MMC-HVDC systems for the most common faults happened in MMC-HVDC systems covering MMC faults, DC side faults as well as AC side faults. An important part of this paper is devoted to a discussion of the vulnerable spots as well as failure mechanism of the MMC-HVDC system covering switching...

  19. DC to DC power converters and methods of controlling the same

    Science.gov (United States)

    Steigerwald, Robert Louis; Elasser, Ahmed; Sabate, Juan Antonio; Todorovic, Maja Harfman; Agamy, Mohammed

    2012-12-11

    A power generation system configured to provide direct current (DC) power to a DC link is described. The system includes a first power generation unit configured to output DC power. The system also includes a first DC to DC converter comprising an input section and an output section. The output section of the first DC to DC converter is coupled in series with the first power generation unit. The first DC to DC converter is configured to process a first portion of the DC power output by the first power generation unit and to provide an unprocessed second portion of the DC power output of the first power generation unit to the output section.

  20. Selection of DC voltage magnitude using Fibonacci series for new hybrid asymmetrical multilevel inverter with minimum PIV

    Directory of Open Access Journals (Sweden)

    M.R. Banaei

    2014-09-01

    Full Text Available Multilevel inverters are suggested to obtain high quality output voltage. In this paper, a new hybrid configuration is proposed, obtained by cascading one four switches H-bridge cell with a family of multilevel inverters. In addition, by the use of specific sequence for value of DC sources named Fibonacci series, asymmetrical topology of proposed inverter is introduced. Main advantages are that proposed inverter has least Peak Inverse Voltage (PIV than other conventional multilevel converters in both symmetric and asymmetric modes. Also, this topology doubles the number of output levels using only one cascaded four switches H-bridge cell. The PCI-1716 DAQ using PC has been used to generate switching pulses in experimental results. For presenting valid performance of proposed configuration, simulation results carried out by MATLAB/SIMULINK software and the validity of the proposed multilevel inverter is verified by experimental results.

  1. A Feed-Forward Control Realizing Fast Response for Three-Branch Interleaved DC-DC Converter in DC Microgrid

    Directory of Open Access Journals (Sweden)

    Haojie Wang

    2016-07-01

    Full Text Available It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC is proposed for storage batteries in DC microgrids. The working principle of TIDC is analyzed, and the factors influencing the response rate based on the dual-loop constant voltage control for TIDC are discussed, and then the method of feed-forward control for TIDC is studied to improve the response rate for load changing. A prototype of the TIDC is developed and an experimental platform is built. The experiment results show that DC bus voltage sags or swells caused by load changing can be reduced and the time for voltage recovery can be decreased significantly with the proposed feed-forward control.

  2. SoC-Based Output Voltage Control for BESS with a Lithium-Ion Battery in a Stand-Alone DC Microgrid

    Directory of Open Access Journals (Sweden)

    Seung-Yeong Yu

    2016-11-01

    Full Text Available This paper proposes a new DC output voltage control for a battery energy storage system (BESS with a lithium-ion battery based on the state of charge (SoC. The proposed control scheme was verified through computer simulations for a typical stand-alone DC microgrid, which consists of a BESS, photovoltaic (PV panel, engine generator (EG, and DC load. A scaled hardware prototype for a stand-alone DC microgrid was set up in the lab, in which the proposed control scheme was loaded in a DSP controller. The experimental results were compared with the simulation results for performance verification. The proposed control scheme provides relatively lower variation of the DC grid voltage than the conventional droop control.

  3. Design of piezoelectric transformer for DC/DC converter with stochastic optimization method

    Science.gov (United States)

    Vasic, Dejan; Vido, Lionel

    2016-04-01

    Piezoelectric transformers were adopted in recent year due to their many inherent advantages such as safety, no EMI problem, low housing profile, and high power density, etc. The characteristics of the piezoelectric transformers are well known when the load impedance is a pure resistor. However, when piezoelectric transformers are used in AC/DC or DC/DC converters, there are non-linear electronic circuits connected before and after the transformer. Consequently, the output load is variable and due to the output capacitance of the transformer the optimal working point change. This paper starts from modeling a piezoelectric transformer connected to a full wave rectifier in order to discuss the design constraints and configuration of the transformer. The optimization method adopted here use the MOPSO algorithm (Multiple Objective Particle Swarm Optimization). We start with the formulation of the objective function and constraints; then the results give different sizes of the transformer and the characteristics. In other word, this method is looking for a best size of the transformer for optimal efficiency condition that is suitable for variable load. Furthermore, the size and the efficiency are found to be a trade-off. This paper proposes the completed design procedure to find the minimum size of PT in need. The completed design procedure is discussed by a given specification. The PT derived from the proposed design procedure can guarantee both good efficiency and enough range for load variation.

  4. Results of the CESI-CPRI research on extruded cables under DC voltage

    Energy Technology Data Exchange (ETDEWEB)

    Mosca, W.

    1988-10-01

    This paper describes extensive feasibility studies (involving power frequency withstand, partial discharge, short and long duration stress, lighting impulse and polarity reversal tests) on the the use of extruded DC cables for HVDC links. The results indicate that: either XLPe or EPr insulated cables, although not optimized for DC, show dielectric performances under DC stress that may be considered satisfactory (a mean working stress of around 25 kV/mm appears a realistic figure to be attained with proper materials and manufacturing technology); the behaviour under transient stress seems satisfactory (a fundamental role is played by the absence of defects and by the quality of the interfaces between inner/outer semiconductive screen and main insulation); a suitable protection to prevent moisture penetration in the insulation must be provided in order to avoid a significant reduction in cable dielectric performances (the use of a laminated protective covering could be in an interesting solution).

  5. Compensation of DC-link voltage oscillations in grid connected PV systems

    Directory of Open Access Journals (Sweden)

    Carlos Andrés Ramos Paja

    2012-01-01

    Full Text Available Se presenta una técnica para compensar el efecto de las oscilaciones en el enlace DC en sistemas fotovoltaicos. Las principales características de la técnica son: la compensación se aplica directamente al ciclo de trabajo, por tanto es simple de integrar con sistemas tradicionales de maximización de potencia; y el cálculo de la compensación es independiente de los parámetros del sistema, por tanto el diseño es general. Se proveen ecuaciones explicitas para sistemas fotovoltaicos basados en convertidores dc/dc tipo Boost, Buck y Buck-Boost. Finalmente, la solución se valida a través de resultados experimentales.

  6. An Overview of Low Voltage DC Distribution Systems for Residential Applications

    DEFF Research Database (Denmark)

    Diaz, Enrique Rodriguez; Firoozabadi, Mehdi Savaghebi; Quintero, Juan Carlos Vasquez;

    2015-01-01

    The concept of a microgrid has drawn the interest of research community in recent years. The most interesting aspects are the integration of renewable energy sources and energy storage systems at the consumption level, aiming to increase power quality, reliability and efficiency. On top of this...... applications. Several publications that study the potential energy savings and overall advantages of the LVDC distribution systems are analysed. Different power architectures and topologies are discussed. The existing demonstration facilities where LVDC distribution systems have been implemented are also shown......., the increasing of DC-based loads has re-open the discussion of DC vs AC distribution systems. As a consequence a lot of research has been done on DC distribution systems and its potential for residential applications. This paper presents an overview of the LVDC distribution systems used in residential...

  7. DC link current simulation of voltage source inverter with random space vector pulse width modulation

    Directory of Open Access Journals (Sweden)

    Chen Guoqiang

    2016-01-01

    Full Text Available Aiming at analysis complexity, a simulation model is built and presented to analyze and demonstrate the characteristics of the direct current (DC link current of the three-phase two-level inverter with the random space vector pulse width modulation (SVPWM strategy. The developing procedure and key subsystems of the simulation model are given in detail. Several experiments are done using the simulation model. The results verify the efficiency and convenience of the simulation model and show that the random SVPWM scheme, especially the random switching frequency scheme, can efficiently suppress the harmonic peaks of the DC link current.

  8. Suppression of surface charge accumulation on Al{sub 2}O{sub 3}-filled epoxy resin insulator under dc voltage by direct fluorination

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Boya; Zhang, Guixin, E-mail: guixin@mail.tsinghua.edu.cn; Li, Chuanyang; He, Jinliang [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Wang, Qiang [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); School of Mechatronic Engineering, Beijing Institute of Technology, Beijing 100081 (China); An, Zhenlian [Department of Electrical Engineering, Tongji University, Shanghai 201804 (China)

    2015-12-15

    Surface charge accumulation on insulators under high dc voltage is a major factor that may lead to the reduction of insulation levels in gas insulated devices. In this paper, disc insulators made of Al{sub 2}O{sub 3}-filled epoxy resin were surface fluorinated using a F{sub 2}/N{sub 2} mixture (12.5% F{sub 2}) at 50 °C and 0.1 MPa for different durations of 15 min, 30 min and 60 min. A dc voltage was applied to the insulator for 30 min and the charge density on its surface was measured by an electrostatic probe. The results revealed significant lower surface charge densities on the fluorinated insulators in comparison with the original one. Surface conductivity measurements indicated a higher surface conductivity by over three orders of magnitude after fluorination, which would allow the charges to transfer along the surface and thus may suppress their accumulation. Further, attenuated total reflection infrared analysis and surface morphology observations of the samples revealed that the introduction of fluoride groups altered the surface physicochemical properties. These structure changes, especially the physical defects reduced the depth of charge traps in the surface layer, which was verified by the measurement of energy distributions of the electron and hole traps based on the isothermal current theory. The results in this paper demonstrate that fluorination can be a promising and effective method to suppress surface charge accumulation on epoxy insulators in gas insulated devices.

  9. KEY COMPARISON Final report on APMP international comparison APMP.EM-K9: High voltage AC-DC transfer standards

    Science.gov (United States)

    Wei, Yih-Cheng; Yeh, Hsin-Da

    2010-01-01

    The international key comparison APMP.EM-K9 of AC-DC high voltage transfer standards with 12 participants was carried out from June 2000 to January 2004. This comparison offers the same range and frequencies as BIPM key comparison CCEM-K9, voltages at 500 V and 1000 V, frequency from 1 kHz to 100 kHz. This comparison provides the national metrology institutes (NMIs) of the APMP member economies with an opportunity to link the values of their standards for AC-DC transfer difference to the international reference values. The results of the majority of the participating NMIs show an agreement with the reference value within the associated expanded uncertainty given by the individual NMI. The agreement of the results and the tables of the degree of equivalence of the participants are included. The results have been linked to the key comparison CCEM-K9. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  10. Epoxy Based Nanodielectrics for High Voltage DC Applications: Synthesis, Dielectric Properties and Space Charge Dynamics

    NARCIS (Netherlands)

    Andritsch, T.M.

    2010-01-01

    Main goal of the research described in this PhD thesis was to determine the influences of filler size, material and distribution on the DC breakdown strength, permittivity and space charge behaviour of nanocomposites. This should lay the groundwork for tailored insulation materials for HVDC

  11. Epoxy Based Nanodielectrics for High Voltage DC Applications: Synthesis, Dielectric Properties and Space Charge Dynamics

    NARCIS (Netherlands)

    Andritsch, T.M.

    2010-01-01

    Main goal of the research described in this PhD thesis was to determine the influences of filler size, material and distribution on the DC breakdown strength, permittivity and space charge behaviour of nanocomposites. This should lay the groundwork for tailored insulation materials for HVDC applicat

  12. Using variable DC sources in order to improve the voltage quality of a multilevel STATCOM with low frequency modulation

    DEFF Research Database (Denmark)

    Dowlatabadi, Mohammadkazem Bakhshizadeh; Najjar, Mohammad; Blaabjerg, Frede

    2016-01-01

    In this paper, a Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM) method, which utilizes adjustable dc links, is presented for a Static Synchronous Compensator (STATCOM) based on Cascaded H-Bridge (CHB) multilevel converter. The proposed switching algorithm is able to fix the capac...... of the proposed method is verified by simulations in Matlab/Simulink environment....

  13. A highly efficient PV system using a series connection of DC-DC converter output with a photovoltaic panel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ho-sung [Department of Electrical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea); New and Renewable Energy System Research Center, Korea Electro-technology Research Institute, 28-1, Sungju-dong Changwon-si, Kyungsannam-do, 641-120 (Korea); Kim, Jong-Hyun; Min, Byung-Duk; Yoo, Dong-Wook [New and Renewable Energy System Research Center, Korea Electro-technology Research Institute, 28-1, Sungju-dong Changwon-si, Kyungsannam-do, 641-120 (Korea); Kim, Hee-Je [Department of Electrical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea)

    2009-11-15

    A photovoltaic (PV) power conditioning system (PCS) must have high conversion efficiency and low cost. Generally, a PV PCS uses either a single string converter or a multilevel module integrated converter (MIC). Each of these approaches has both advantages and disadvantages. For a high conversion efficiency and low cost PV module, a series connection of a module integrated DC-DC converter output with a photovoltaic panel was proposed. The output voltage of the PV panel is connected to the output capacitor of the fly-back converter. Thus, the converter output voltage is added to the output voltage of the PV panel. The isolated DC-DC converter generates only the difference voltage between the PV panel voltage and the required total output voltage. This method reduces the power level of the DC-DC converter and enhances energy conversion efficiency compared with a conventional DC-DC converter. (author)

  14. 无刷直流电动机调压系统BUCK直流变换仿真%Simulation on BUCK DC Transformer of Brushless DC Motor Voltage Regulation System

    Institute of Scientific and Technical Information of China (English)

    张旭

    2016-01-01

    In order to improve the brushless DC motor voltage regulation system voltage conversion efficiency and reduce power consumption, based on BUCK transformer chopper voltage regulation technology was put forward. In this paper elaborat-ed the circuit structure and mathematical model of brushless DC motor with BUCK mode, analyzed technology of DC converter and BUCK dc transform. Take advantage of MATLAB software SIMULINK module modeling BUCK DC converter, simula-tion for BUCK DC transform under the 20kHz working frequency, got the switch tube gate trigger pulse, inductive voltage and inductance current, output voltage, switching tube and diode current simulation curve. The simulation results and theoretical analysis of waveform basically the same, the rationality was proved of BUCK DC converter model.%为了提高无刷直流电动机调压系统电压转换效率、降低功率消耗,提出基于BUCK变换的斩波调压技术。在阐述BUCK模式下无刷直流电动机电路结构、数学模型基础上,对直流变换器和BUCK直流变换技术进行分析。利用MATLAB软件SIMULINK模块对BUCK直流变换器进行建模,对20kHz工作频率下BUCK直流变换进行仿真,得到开关管门极触发脉冲、电感电压、电感电流、输出电压、开关管电流和二极管电流仿真曲线。仿真结果与理论分析波形基本一致,表明BUCK直流变换器模型的合理性。

  15. DLC Films Deposited by the DC PACVD Method

    Directory of Open Access Journals (Sweden)

    D. Palamarchuk

    2003-01-01

    Full Text Available DLC (Diamond-Like Carbon coatings have been suggested as protective surface layers against wear. However hard DLC coatings, especially those of greater thickness, have poor adhesion to substrates. We have used several ways to increase the adhesion of DLC coatings prepared by the PACVD (Plasma Assisted Chemical Vapour Deposition method on steel substrates. One of these is the DC PACVD method for preparing DLC films.

  16. DLC Films Deposited by the DC PACVD Method

    OpenAIRE

    D. Palamarchuk; M. Zoriy; J. Gurovič; F. Černý; S. Konvičková; I. Hüttel

    2003-01-01

    DLC (Diamond-Like Carbon) coatings have been suggested as protective surface layers against wear. However hard DLC coatings, especially those of greater thickness, have poor adhesion to substrates. We have used several ways to increase the adhesion of DLC coatings prepared by the PACVD (Plasma Assisted Chemical Vapour Deposition) method on steel substrates. One of these is the DC PACVD method for preparing DLC films.

  17. Improved Phasor Estimation Method for Dynamic Voltage Restorer Applications

    DEFF Research Database (Denmark)

    Ebrahimzadeh, Esmaeil; Farhangi, Shahrokh; Iman-Eini, Hossein;

    2015-01-01

    The dynamic voltage restorer (DVR) is a series compensator for distribution system applications, which protects sensitive loads against voltage sags by fast voltage injection. The DVR must estimate the magnitude and phase of the measured voltages to achieve the desired performance. This paper...... proposes a phasor parameter estimation algorithm based on a recursive variable and fixed data window least error squares (LES) method for the DVR control system. The proposed algorithm, in addition to decreasing the computational burden, improves the frequency response of the control scheme based...... on the fixed data window LES method. The DVR control system based on the proposed algorithm provides a better compromise between the estimation speed and accuracy of the voltage and current signals and can be implemented using a simple and low-cost processor. The results of the studies indicate...

  18. Study of DC capacitor parameter selection based on three-phase power supply voltage deviation%基于三相供电电压偏差选取直流电容参数研究

    Institute of Scientific and Technical Information of China (English)

    郭艳清; 冯占伟; 袁天驰

    2015-01-01

    In the voltage type PWM AC/DC/AC conversion , the DC side energy-storage filtering capacitor′s parame-ter selection is one of the key factors for stable operation of the converter .In view of the certain inaccuracy in the DC capacitor′s selection , this paper analyzed the principle of the DC side capacitor′s charge and discharge when the AC/DC/AC conversion circuit in steady state , and studied the voltage relationship between the DC side and the AC side of the converter .A mathematical model between capacitor ripple voltage and three-phase power supply voltage deviation is established .Thus, the capacitance parameter selection method based on the three-phase power supply voltage devi-ation is proposed .This paper respectively gives the appropriate analysis and calculations of filter capacitance when three phase and single phase uncontrolled rectifier circuit provides dc power .And through simulation and experimental verification of the DC filter capacitor energy storage method verifies the validity of arguments .%在电压型PWM AC/DC/AC变换中,直流侧储能滤波电容参数的选取是变换器稳定运行的关键因素之一。针对目前直流侧电容选取存在一定的不精确性,分析了AC/DC/AC变换电路稳态时直流电容充放电的原理,对变换器交直流侧电压的关系进行研究,建立了电容纹波电压与三相供电电压偏差之间的数学模型,提出了基于三相供电电压偏差选取直流侧电容参数的方法。分别对单相和三相不可控整流电路提供直流电源时直流侧电容C的合理选取给出了相应的分析和计算,并通过仿真和试验验证了直流储能滤波电容参数确定方法的有效性。

  19. PowerFactory model for multi-terminal HVDC network with DC voltage droop control

    DEFF Research Database (Denmark)

    Korompili, Asimenia; Wu, Qiuwei

    Nowadays, most of the installed HVDC systems are based on line commutated converters (LCC), since this technology offers a series of advantages, mainly low costs and losses. However, voltage source converters (VSCs) have recently drawn more and more attention, due to their high controllability...

  20. High performance AC–DC control power supply for low voltage ride through inverters

    Indian Academy of Sciences (India)

    K Saichand; Akshay Kumrawat; Vinod John

    2016-02-01

    This paper presents a control power supply (CPS) design which is used to feed power to the subsystems of a power converter. The CPS design presented here maintains a constant 24Vdc output even over a wide (90Vrms to 270Vrms ) ac voltage variation at its input for a High Power Converter (HPC). The circuit design and closed loop control design of such a CPS are presented. During starting, the power supply to the control circuitry of the CPS in turn is obtained using a separate start-up power supply. The various design issues and details of the on-board power supply and start-up power circuit to ensure the reliable start-up and shut down of the CPS are analyzed. The CPS was tested for wide input voltage range (vin) and the performance validates the design. The CPS has also been tested for an input side voltage sag and its performance allows the HPC to meet the low voltage ride-through requirements.

  1. Breakdown Characteristic Analysis of Paper- Oil Insulation under AC and DC Voltage

    Science.gov (United States)

    Anuar, N. F.; Jamail, N. A. M.; Rahman, R. A.; Kamarudin, M. S.

    2017-08-01

    This paper presents the study of breakdown characteristic of Kraft paper insulated with two different types of insulating fluid, which are Palm oil and Coconut oil. Palm oil and Coconut oil are chosen as the alternative fluid to the transformer oil because it has high potential and environmentally-friendly. The Segezha Kraft papers with various thicknesses (65.5 gsm, 75 gsm, 85gsm, 90 gsm) have been used in this research. High Voltage Direct Current (HVDC), High Voltage Alternating Current (HVAC) and carbon track and severity analysis is conducted to observe the sample of aging Kraft paper. These samples have been immersed using Palm oil and Coconut oil up to 90 days to observe the absorption rate. All samples started to reach saturation level at 70 days of immersion. HVDC and HVAC breakdown experiments have been done after the samples had reached the saturation level based on normal condition, immersed in Palm oil and immersed in Coconut oil. All samples immersed in liquid show different breakdown voltage reading compared to normal condition. The analysis of carbon track and severity on surface has been done using Analytical Scanning Electron Microscope (SEM) Analysis. The results of the experiment show that the sample of Kraft paper immersed in Palm oil was better than Coconut oil immersed sample. Therefore the sample condition was the main factor that determines the value of breakdown voltage test. Introduction

  2. Harmonic elimination technique for a single-phase multilevel converter with unequal DC link voltage levels

    DEFF Research Database (Denmark)

    Ghasemi, N.; Zare, F.; Boora, A.A.

    2012-01-01

    on the output voltage quality by reducing its total harmonic distortion, which must take into consideration for some applications such as uninterruptable power supply, motor drive systems and piezoelectric transducer excitation. In order to verify the proposed modulation technique, MATLAB simulations...

  3. A Novel Method for Sensorless Speed Detection of Brushed DC Motors

    Directory of Open Access Journals (Sweden)

    Ernesto Vazquez-Sanchez

    2016-12-01

    Full Text Available Many motor applications require accurate speed measurement. For brushed dc motors, speed can be measured with conventional observers or sensorless observers. Sensorless observers have the advantage of not requiring any external devices to be attached to the motor. Instead, voltage and/or current are measured and used to estimate the speed. The sensorless observers are usually divided into two groups: those based on the dynamic model, and those based on the ripple component. This paper proposes a method that measures the current of brushed dc motors and analyses the position of its spectral components. From these spectral components, the method estimates the motor speed. Three tests, performed each with the speeds ranging from 2000 to 3000 rpm either at constant-speed, at slowly changing speeds, or at rapidly changing speeds, showed that the average error was below 1 rpm and that the deviation error was below 1.5 rpm. The proposed method: (i is a novel method that is not based on either the dynamic model or on the ripple component; (ii requires only the measurement of the current for the speed estimation; (iii can be used for brushed dc (direct current motors with a large number of coils; and (iv achieves a low error in the speed estimation.

  4. Simplified dc to dc converter

    Science.gov (United States)

    Gruber, R. P. (Inventor)

    1984-01-01

    A dc to dc converter which can start with a shorted output and which regulates output voltage and current is described. Voltage controlled switches directed current through the primary of a transformer the secondary of which includes virtual reactance. The switching frequency of the switches is appropriately varied to increase the voltage drop across the virtual reactance in the secondary winding to which there is connected a low impedance load. A starting circuit suitable for voltage switching devices is provided.

  5. Power Flow Analysis for Low-Voltage AC and DC Microgrids Considering Droop Control and Virtual Impedance

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay Kumar; Savaghebi, Mehdi

    2017-01-01

    adequate power flow studies. In this paper, power flow analyses for both AC and DC microgrids are formulated and implemented. The mathematical models for both types of microgrids considering the concept of virtual impedance are used to be in conformity with the practical control of the distributed...... generators. As a result, calculation accuracy is improved for both AC and DC microgrid power flow analyses, comparing with previous methods without considering virtual impedance. Case studies are conducted to verify the proposed power flow analyses in terms of convergence and accuracy. Investigation...

  6. GAPOD and GA DC-voltage regulator based UPFC supplementary cont roller for damping low frequency oscillations in Multi-machine power systems

    Directory of Open Access Journals (Sweden)

    Dakka. Obulesu, Dr. S.F. Kodad, Dr. B.V. Sankar Ram

    2013-08-01

    Full Text Available The Unified Power Flow Controller (UPFC is the most versatile device in the FACTS (Flexible AC Transmission Systems which has emerged to enhance power system stability spectrum and dynamic performance. This paper briefs the effectiveness of the proposed GAPOD and GA DC-voltage regulator which has been tested on a 3-Machine, 9-Bus power system in comparison with Particle swarm optimization based Multi-Stage Fuzzy (PSOMSF DC-voltage regulator. The non-linear time-domain simulation results show thatthe oscillations of synchronous machines could be quickly and effectively damped with proposed GAPOD and GA DC-voltage regulator. The construction and implementation of this controller is fairly easy, which can be useful in real world power system.

  7. Design of a high DC voltage generator and D-T fuser based on particle accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Wagner L.; Campos, Tarcisio P.R., E-mail: wagnerleite@ufmg.b, E-mail: campos@nuclear.ufmg.b [Universidade Federal de Minas Gerais (DEN/ UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Nuclear

    2011-07-01

    This paper approaches a design and simulation of a high voltage Cockcroft Walton multiplier and a compact size deuteron accelerator addressed in neutron generation by d-t fusion. We proposed a circuit arrangement, which was led to simulations. The particle accelerator was computer-generated providing particle transport and electric potential analysis. As results, the simulated voltage multiplier achieved 119 kV, and the accelerator presented a deuteron beam current up to 15 mA, achieving energies in order to 100 keV. In conclusion, the simulation motivates experimental essays in order to investigate the viability of a deuteron accelerator powered by a Cockcroft-Walton source. Such d-t fusor shall produce an interesting ion beam profile, reaching energy values near the d-t fusion cross section peak. (author)

  8. A novel position-sensorless control method for brushless DC motors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.Z., E-mail: Z_X_Z2000@163.co [School of Electrical and Information Engineering, Hunan University, Changsha (China) and School of Computer and Communication, Hunan Institute of Engineering, Xiangtan (China); Wang, Y.N. [School of Electrical and Information Engineering, Hunan University, Changsha (China)

    2011-03-15

    This paper presents the design and implementation of a high performance position-sensorless control scheme for the extensively used brushless DC (BLDC) motors. In the proposed method, with proper PWM strategy, instead of detecting the zero-crossing point (ZCP) of the nonexcited motor back electromagnetic force (EMF) or the average motor terminal to neutral voltage, the true zero-crossing points of back EMF are extracted directly from the difference of the specific average line-to-line voltages with simple RC circuits and comparators. In contrast to conventional methods, the neutral voltage is not needed and the diode freewheeling currents in the nonconducted phase are eliminated completely; therefore, the commutation signals are more accurate and insensitive to the common-mode noise. Moreover, 100% pulse-width-modulation (PWM) duty ratio control of BLDC motors is provided with the presented method. As a result, the proposed method makes it possible to achieve good motor performance over a wide speed range and to simplify the starting procedure. The detailed circuit model is analyzed and some experimental results obtained from a sensorless prototype are shown to verify the analysis and confirm the validity of the proposed method.

  9. Investigation of surface modifications in ethylene propylene diene monomer (EPDM) rubber due to tracking under a.c. and d.c. voltages

    Indian Academy of Sciences (India)

    R Sarathi; Uma Maheswar Rao

    2001-12-01

    In the present work, tracking phenomena has been studied with the ethylene propylene diene monomer (EPDM) material under the a.c. and d.c. voltages, with ammonium chloride/acid rain solution as the contaminant. It is noticed that the tracking time depends on the conductivity and flow rate of the contaminant. The physico-chemical analyses viz. wide angle X-ray diffraction (WAXD), thermo-gravimetric differential thermal analysis (TG-DTA) and the differential scanning calorimetry (DSC) studies, were carried out and it was concluded that the tracking process is a surface degradation process. The tracking time is different for a.c. and d.c. voltages.

  10. Evaluation of E-J characteristics of YBCO coated-conductor by AC inductive method using third-harmonic voltage

    Energy Technology Data Exchange (ETDEWEB)

    Fukumoto, Yosuke; Kiuchi, M.; Otabe, E.S.; Matsushita, T.; Sawa, H.; Inoue, M.; Kiss, T.; Iijima, Y.; Kakimoto, K.; Saitoh, T

    2004-10-01

    The E-J characteristics were measured for a YBCO coated-conductor by using AC inductive method of third-harmonic voltage. The results are compared with the measurements obtained by the four probe method and DC relaxation method of magnetization. The results by three kinds of measurements meet approximately on a single curve and E-J curve in a wide range of electric field is obtained. Hence, the third-harmonic voltage method is useful for a continuous measurement of J{sub c} property of long coated tape. The obtained E-J characteristics are argued.

  11. Synthesis of a CNT-grafted TiO{sub 2} nanocatalyst and its activity triggered by a DC voltage

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, C-S [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621 (China); Tseng, Y-H [Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, 310 (China); Lin, H-Y [Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716 (United States); Huang, C-H [Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, 310 (China); Shen, C-Y [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621 (China); Li, Y-Y [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621 (China); Shah, S Ismat [Department of Materials Sciences and Engineering, University of Delaware, Newark, DE 19716 (United States); Huang, C-P [Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716 (United States)

    2007-11-21

    Carbon nanotube (CNT)-grafted TiO{sub 2} (CNT/TiO{sub 2}) was synthesized as an electrically conductive catalyst that exhibits redox ability under electrical excitation besides ultraviolet (UV) irradiation. The CNT/TiO{sub 2} material was synthesized by a two-step process. Ni nanoparticles were photodeposited onto TiO{sub 2} first. The Ni nanoparticles then served as seeds for the growth of CNTs using the chemical vapor deposition (CVD) of C{sub 2}H{sub 2}. The CNT/TiO{sub 2} nanocomposite exhibits strong oxidation activity toward NO gas molecules via both photocatalysis under UV irradiation and electrocatalysis under a DC voltage of 500 V in dark conditions.

  12. Benchmarking of 3D space charge codes using direct phase space measurements from photoemission high voltage DC gun

    CERN Document Server

    Bazarov, Ivan V; Gulliford, Colwyn; Li, Yulin; Liu, Xianghong; Sinclair, Charles K; Soong, Ken; Hannon, Fay

    2008-01-01

    We present a comparison between space charge calculations and direct measurements of the transverse phase space for space charge dominated electron bunches after a high voltage photoemission DC gun followed by an emittance compensation solenoid magnet. The measurements were performed using a double-slit setup for a set of parameters such as charge per bunch and the solenoid current. The data is compared with detailed simulations using 3D space charge codes GPT and Parmela3D with initial particle distributions created from the measured transverse and temporal laser profiles. Beam brightness as a function of beam fraction is calculated for the measured phase space maps and found to approach the theoretical maximum set by the thermal energy and accelerating field at the photocathode.

  13. Benchmarking of 3D space charge codes using direct phase space measurements from photoemission high voltage dc gun

    Directory of Open Access Journals (Sweden)

    Ivan V. Bazarov

    2008-10-01

    Full Text Available We present a comparison between space charge calculations and direct measurements of the transverse phase space of space charge dominated electron bunches from a high voltage dc photoemission gun followed by an emittance compensation solenoid magnet. The measurements were performed using a double-slit emittance measurement system over a range of bunch charge and solenoid current values. The data are compared with detailed simulations using the 3D space charge codes GPT and Parmela3D. The initial particle distributions were generated from measured transverse and temporal laser beam profiles at the photocathode. The beam brightness as a function of beam fraction is calculated for the measured phase space maps and found to approach within a factor of 2 the theoretical maximum set by the thermal energy and the accelerating field at the photocathode.

  14. DC conduction and breakdown characteristics of Al2O3/cross-linked polyethylene nanocomposites for high voltage direct current transmission cable insulation

    Science.gov (United States)

    Park, Yong-Jun; Kwon, Jung-Hun; Sim, Jae-Yong; Hwang, Ju-Na; Seo, Cheong-Won; Kim, Ji-Ho; Lim, Kee-Joe

    2014-08-01

    We have discussed a cross-linked polyethylene (XLPE) nanocomposite insulating material that is able to DC voltage applications. Nanocomposites, which are composed in polymer matrix mixed with nano-fillers, have received considerable attention because of their potential benefits as dielectrics. The nano-sized alumina oxide (Al2O3)/XLPE nanocomposite was prepared, and three kinds of test, such as DC breakdown, DC polarity reversal breakdown, and volume resistivity were performed. By the addition of nano-sized Al2O3 filler, both the DC breakdown strength and the volume resistivity of XLPE were increased. A little homogeneous space charge was observed in Al2O3/XLPE nanocomposite material in the vicinity of electrode through the polarity reversal breakdown test. From these results, it is thought that the addition of Al2O3 nano-filler is effective for the improvement of DC electrical insulating properties of XLPE.

  15. Dual Input High Step-up DC-DC Converters With Voltage Multiplier Cells%一种基于倍压单元的双输入高增益直流变换器

    Institute of Scientific and Technical Information of China (English)

    孙鹏菊; 李正宇; 张冀; 周雒维

    2016-01-01

    According to the problems that more than one energy source, low output voltage of the battery module and unstable output power in the distributed photovoltaic power generation system, a dual input high step-up DC-DC converter with capacitor-diode multiplier cells was proposed in this paper. The proposed topology has the following advantages: the voltage gain is high, the voltage stress of the switches is low, there are more control freedoms and the sources can deliver power to the load with flexible power management methods. Firstly, the operation mode and the performance characteristics of the converter were presented in detail. Secondly, the steady state analysis, the voltage and current stresses of the switches and the relationship between the input currents were also introduced. Finally, the correctness and feasibility of the proposed circuit topology and the theoretical analysis were fully verified by a 1000W prototype.%针对分布式光伏发电系统电池模块多、输出电压低、功率不稳定等问题,提出了一种基于电容-二极管倍压单元的双输入高增益Boost型直流变换器。该变换器具有电压调节增益高、开关器件电压应力小、控制自由度多、各输入源功率可灵活分配等优点。首先分析了双输入高增益 Boost变换器的工作原理及性能特点,给出了变换器的稳态关系式及开关管电压电流应力计算结果,最后通过一台1000W的实验样机,验证了电路拓扑和理论分析的可行性和正确性。

  16. DC buffering and floating current for a high voltage IMB application

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, J. L. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-08-01

    An interface technique for the latest generation of the Impedance Measurement Box (IMB) has been conceived to enable measurement of impedance spectra for battery modules up to 300V. A 300V capable or higher IMB is an enabling technology for in-situ diagnostics within electric vehicle charging stations or battery back-ups within power distribution sub-stations. It is possible that the existing IMB can be adapted via a 300V interface module to a test battery with voltage significantly greater than 50V. Recently a new concept was conceived for the calibration, algorithm and electronics of the IMB. That algorithm and calibration for that concept have been physically validated. The principal feature of the new electronics is the floating current source excitation of the battery under test. The single ended current excitation of the battery under test, used in the 50V IMB, requires that the negative terminal of the test battery must be the analog ground for the IMB. The new floating current technique allows the test battery to be fully high impedance isolated for a measurement. That isolation will improve IMB noise immunity and enable interrogation of cells internal to a battery module. All these techniques still use the same rapid concept for impedance measurement with the IMB. The purpose of this disclosure is to provide an overview of the analytical validation for three concepts to interface the floating current excitation to a high voltage battery. Recursive simulation models were used in different test scenarios to validate the various new concepts. The analysis will show that it is possible to interface the floating signal current to obtain an impedance measurement on a high voltage test battery. Additionally, the analysis will investigate stress seen by electronics while testing a 300V battery.

  17. Impurity Deionization Effects on Surface Recombination DC Current-Voltage Characteristics in MOS Transistors

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zuhui [Lee-Kuan-Yew Postdoctoral Fellow, 2007-2010, Nanyang Technological University, Singapore 639798 (Singapore); Jie Binbin; Sah Chihtang, E-mail: bb_jie@msn.com [Department of Physics, Xiamen University, Xiamen 361005 (China)

    2010-12-15

    Impurity deionization on the direct-current current-voltage characteristics from electron-hole recombination (R-DCIV) at SiO{sub 2}/Si interface traps in MOS transistors is analyzed using the steady-state Shockley-Read-Hall recombination kinetics and the Fermi distributions for electrons and holes. Insignificant distortion is observed over 90% of the bell-shaped R-DCIV curves centered at their peaks when impurity deionization is excluded in the theory. This is due to negligible impurity deionization because of the much lower electron and hole concentrations at the interface than the impurity concentration in the 90% range. (invited papers)

  18. On-line Identification of the DC motor Parameters by using Least Mean Square Recursive Method

    Directory of Open Access Journals (Sweden)

    Marian Gaiceanu

    2014-09-01

    Full Text Available The on-line least square parameters (electrical and mechanical identification method of the separately DC motor is presented in this paper. The parameters of the DC machine are time dependent; therefore, for the DC drive control the on-line parameters identification procedure is mandatory. By knowing accurately the DC motor parameters, the parameters of the DC speed and current cascade controllers can be obtained.

  19. Precise method for determining avalanche breakdown voltage of silicon photomultipliers

    Science.gov (United States)

    Chirikov-Zorin, I.

    2017-07-01

    A physically motivated method is proposed for determining the avalanche breakdown voltage of silicon photomultipliers (SiPM). The method is based on measuring the dependence of the relative photon detection efficiency (PDErel) on the bias voltage when one type of carriers (electron or hole) is injected into the avalanche multiplication zone of the p-n junction. The injection of electrons or holes from the base region of the SiPM semiconductor structure is performed using short-wave or long-wave light. At a low overvoltage (1-2 V) the detection efficiency is linearly dependent on the bias voltage; therefore, extrapolation to zero PDErel value determines the SiPM avalanche breakdown voltage with an accuracy within a few millivolts.

  20. Ultra-High Voltage DC Convertor Station Equipment Condition Data Access Technology Based on multi-Source Heterogeneous Fusion

    Science.gov (United States)

    Wang, Feng; Zhang, Bo-wen; Han, Shuai; Ren, Wei; Xu, Hai-jun; Fu, Long-ming

    2017-07-01

    With the large-scale construction of special high-voltage project, as well as power supply reliability, security, economic and other increasingly demanding, state monitoring equipment involved in more and more monitoring projects and more and more monitoring data, because these data exist in multiple isolated systems in the Ultra-High Voltage(UHV) AC-DC substation, there is no data sharing mechanism, so a holistic analysis, application and sharing approach for the data set will need a deep consideration. In this paper, the equipment condition monitoring system frame of the UHV converter station and the scheme of the equipment state data access of UHV converter station based on the multi-source and heterogeneous data fusion are presented. Then, data exchange technology of UHV equipment state early warning center was introduced, and a data access and conversion device in the Zhongzhou converter station was deployed to solve the timeliness and functionality difficult of the existing system to meet the requirements of UHV operation and maintenance support.

  1. Characteristics of a Normal Glow Discharge Excited by DC Voltage in Atmospheric Pressure Air

    Science.gov (United States)

    Li, Xuechen; Zhao, Huanhuan; Jia, Pengying

    2013-11-01

    Atmospheric pressure glow discharges were generated in an air gap between a needle cathode and a water anode. Through changing the ballast resistor and gas gap width between the electrodes, it has been found that the discharges are in normal glow regime judged from the current-voltage characteristics and visualization of the discharges. Results indicate that the diameter of the positive column increases with increasing discharge current or increasing gap width. Optical emission spectroscopy is used to calculate the electron temperature and vibrational temperature. Both the electron temperature and the vibrational temperature increases with increasing discharge current or increasing gap width. Spatially resolved measurements show that the maxima of electron temperature and vibrational temperature appeared in the vicinity of the needle cathode.

  2. Pattern recognition of typical defects in high-voltage storage capacitors based on DC partial discharge

    Institute of Scientific and Technical Information of China (English)

    WU GuangNing; BIAN ShanShan; ZHOU LiRen; ZHANG XueQin; RAN HanZheng; YU ChengLong

    2009-01-01

    High-voltage storage capacitors(hereinafter call capacitors for short)have been widely used in pulsed power technology.In accordance with the actual work conditions of capacitors,direct current partial discharge(DCPD)detection was put forward.The whole test system was based on the impedance balance circuit characterized by good configuration and anti-interference ability.Through DCPD detection on capacitors which contained four typical defects respectively,test results revealed that DCPD signals could well reflect the state of capacitor insulation.DCPD distribution spectra of capacitors containing four typical defects were obviously different.Defects in capacitors could be exactly judged by computer-aided pattern recognition based on support vector machine(SVM).

  3. Pattern recognition of typical defects in high-voltage storage capacitors based on DC partial discharge

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    High-voltage storage capacitors(hereinafter call capacitors for short)have been widely used in pulsed power technology.In accordance with the actual work conditions of capacitors,direct current partial discharge(DCPD)detection was put forward.The whole test system was based on the impedance balance circuit characterized by good configuration and anti-interference ability.Through DCPD detection on capacitors which contained four typical defects respectively,test results revealed that DCPD signals could well reflect the state of capacitor insulation.DCPD distribution spectra of capacitors containing four typical defects were obviously different.Defects in capacitors could be exactly judged by computer–aided pattern recognition based on support vector machine(SVM).

  4. The effect of the dc bias voltage on the x-ray bremsstrahlung and beam intensities of medium and highly charged ions of argon.

    Science.gov (United States)

    Rodrigues, G; Lakshmy, P S; Baskaran, R; Kanjilal, D; Roy, A

    2010-02-01

    X-ray bremsstrahlung measurements from the 18 GHz High Temperature Superconducting Electron Cyclotron Resonance Ion Source, Pantechnik-Delhi Ion Source were measured as a function of negative dc bias voltage, keeping all other source operating parameters fixed and the extraction voltage in the off condition. The optimization of medium and highly charged ions of argon with similar source operating parameters is described. It is observed that the high temperature component of the electron is altered significantly with the help of bias voltage, and the electron population has to be maximized for obtaining higher current.

  5. Origin of dc voltage in type II superconducting flux pumps: field, field rate of change, and current density dependence of resistivity

    Science.gov (United States)

    Geng, J.; Matsuda, K.; Fu, L.; Fagnard, J.-F.; Zhang, H.; Zhang, X.; Shen, B.; Dong, Q.; Baghdadi, M.; Coombs, T. A.

    2016-03-01

    Superconducting flux pumps are the kind of devices which can generate direct current into superconducting circuit using external magnetic field. The key point is how to induce a dc voltage across the superconducting load by ac fields. Giaever (1966 IEEE Spectr. 3 117) pointed out flux motion in superconductors will induce a dc voltage, and demonstrated a rectifier model which depended on breaking superconductivity. van de Klundert et al (1981 Cryogenics 21 195, 267) in their review(s) described various configurations for flux pumps all of which relied on inducing the normal state in at least part of the superconductor. In this letter, following their work, we reveal that a variation in the resistivity of type II superconductors is sufficient to induce a dc voltage in flux pumps and it is not necessary to break superconductivity. This variation in resistivity is due to the fact that flux flow is influenced by current density, field intensity, and field rate of change. We propose a general circuit analogy for travelling wave flux pumps, and provide a mathematical analysis to explain the dc voltage. Several existing superconducting flux pumps which rely on the use of a travelling magnetic wave can be explained using the analysis enclosed. This work can also throw light on the design and optimization of flux pumps.

  6. A Quantities Method of Induction Motor Under Unbalanced Voltage Conditions

    Directory of Open Access Journals (Sweden)

    Ayong Hiendro

    2010-08-01

    Full Text Available The most complete definition for the voltage unbalance is using complex voltage unbalance factor (CVUF that consists of its magnitude and angle. Unfortunately, the definition did not distinguish between undervoltage and overvoltage unbalance conditions. In this paper, the analysis of the motor is performed using the method of symmetrical component and MATLAB software is used to investigate the performance of induction motor. The simulation results show that the International Electrotechnical Commission (IEC definition of the voltage unbalance can be applied to evaluate total copper losses precisely. However, the phase angle of unbalance factor must be included for accurate predicting of peak currents and peak copper losses of the phase windings of the motor.The unbalanced conditions which distinguish between under and over voltage unbalance must also be taken into consideration for assessing all the quantities.

  7. 隔离型DC/DC在高压电压电流源设计中的应用%Application of isolated DC/DC converter in high level voltage and current source design

    Institute of Scientific and Technical Information of China (English)

    黄弋; 周菁

    2012-01-01

    由于隔离型DC/DC的安全性、隔离性等特征,该类器件广泛应用于多个电子、工业领域,本文主要介绍了隔离型DC/DC在高压电压电流源中的应用。本文将隔离型双输出DC/DC引入设计,利用DC/DC的隔离特性,将电压电流源的次级输出作为DC/DC器件参考地,将DC/DC器件的两路输出电压作为相关运算放大器的电源电压。常规高压电压电流源设计中需要大量采用高压运算放大器,采用此方案可使用较少的高压运算放大器及更低的成本实现相同功能,同时降低高压电源对PCB电路板上信号的影响。通过实际测量,文中方案输出稳定、精度高,满足设计与使用要求。文中用功能图纸对此类应用进行了详细说明。%Because of the Characteristics of safety and reliability, isolated DC/DC converter is widely used in many fields, such as electronic field and industry field. This paper describes the application of isolated DC/DC converter in ATE voltage and current source designing. The voltage and current source circuit are mainly realized by Operational amplifiers. When isolated DC/DC converter is used in the design, we can use less Operational amplifiers and cost less to realize the same function. In the project, the two voltage outputs of isolated DC/DC converter are used as power supply of Operational amplifiers, and the secondary output of voltage and current source is used as reference ground. It is effective to reduce system noise of high voltage power supply and to make signal quality on PCB getting better. It was confirmed that the system we discussed in this paper meet the requirements of reliability and precision through the measurement result. The details of the schematic are also describes in the paper

  8. Hysteretic Current Controlled Zvs Dc/Dc Converter For Automobile

    DEFF Research Database (Denmark)

    Cernat, M.; Scortarul, P.; Tanase, A.

    2007-01-01

    A novel bi-directional dc-dc converter with ZVS and interleaving for dual voltage systems in automobiles is presented. A variable frequency extended band hysteretic current control method is proposed. In comparison with classical fixed frequency current control PWM, the reverse polarity peak curr...

  9. Active Power Control with Undead-Band Voltage & Frequency Droop for HVDC Converters in Large Meshed DC Grids

    DEFF Research Database (Denmark)

    Vrana, Til Kristian; Zeni, Lorenzo; Fosso, Olav Bjarte

    A new control method for large meshed HVDC grids has been developed, which helps to keep the active power balance at the AC and the DC side. The method definition is kept wide, leaving the possibility for control parameter optimisation. Other known control methods can be seen as specific examples...... the band, but not set to zero as with a regular dead-band. It operates with a minimum of required communication. New converters can be added to the system without changing the control of the other individual converters. It is well suited to achieve high reliability standards due to the distributed control...

  10. 零电压转换PWMDC/DC变换器的研究%Research on Zero-voltage-transition PWM DC/DC Converters

    Institute of Scientific and Technical Information of China (English)

    高原; 邱新芸

    2005-01-01

    介绍了PWM DC/DC变换器的软开关控制.阐述了零电压转换PWM DC/DC变换器的缺点.研究了带吸收电容的零电压转换PWM DC/DC变换器电路.给出了仿真电路和仿真结果.

  11. Leakage current and stability of acrylic elastomer subjected to high DC voltage

    Science.gov (United States)

    Hammami, S.; Jean-Mistral, C.; Jomni, F.; Gallot-Lavallée, O.; Rain, P.; Yangui, B.; Sylvestre, A.

    2015-04-01

    Dielectric elastomers such as 3M VHB4910 acrylate film have been widely used for electromechanical energy conversion such as actuators, sensors and generators, due to their lightweight, high efficiency, low cost and high energy density. Mechanical and electric properties of such materials have been deeply investigated according to various parameters (temperature, frequency, pre-stress, nature of the compliant electrodes…). Models integrating analytic laws deduced from experiments increase their accuracy. Nevertheless, leakage current and electrical breakdown reduce the efficiency and the lifetime of devices made with these polymers. These two major phenomena are not deeply investigated in the literature. Thus, this paper describes the current-voltage characteristics of acrylate 3M VHB4910 and investigates the stability of the current under high electric field (kV) for various temperatures (from 20°C to 80°C) and over short (300 s) and long (12h) periods. Experimental results show that, with gold electrodes at ambient temperature, the current decreases with time to a stable value corresponding to the conduction current. This decrease occurs during 6 hours, whereas in the literature values of current at short time (less than 1 hour) are generally reported. This decrease can be explained by relaxations mechanisms in the polymer. Schottky emission and Poole-Frenkel emission are both evaluated to explain the leakage current. It emerges from this study that the Schottky effect constitutes the main mechanism of electric current in the 3M VHB4910. For high temperatures, the steady state is reached quickly. To end, first results on the leakage current changes for pre-stretch VHB4910 complete this study.

  12. Calculating magnetic shielding effectiveness for high-power dc comparator by magnetic circuit method

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-wei; REN Shi-yan

    2007-01-01

    Magnetic shielding is very important in the design of a high-power dc comparator. This paper addressed the application of magnetic circuit method to calculate the magnetic shielding effectiveness of high-power dc comparators when an external radial magnetic field is added. The mathematical relationship between the magnetic shielding effectiveness and the parameters of the magnetic shielding body were obtained. To verify the validity of the calculation method, we developped a procedure to measure the magnetic shielding effectiveness of the magnetic body by measuring the induction voltage of the detection winding instead of the magnetic intensity at a point in the magnetic shielding body, making the manipulation much easier. The result calculated with the magnetic circuit method turns out to be closer to the measured one compared with that calculated with a conventional algorithm proposed by Ren, suggesting that the magnetic circuit method is an applicable tool for estimating the toroidal cavity magnetic shielding effectiveness of a heavy current comparator when a radial magnetic field is added.

  13. Design and Implementation of Anti-windup PI Control on DC-DC Bidirectional Converter for Hybrid Vehicle Applications

    Directory of Open Access Journals (Sweden)

    Muh. Zakiyullah Romdlony

    2012-07-01

    Full Text Available Well-regulated DC bus voltage is the important point to guarantee the power demand in hybrid vehicle applications. Voltage regulation can be achieved with control method that build switching signal on DC-DC converter. This paper describes design and small scale experimental results of bus voltage regulation control of the DC-DC bidirectional converter with battery and supercapacitor as energy source. The control system consists of two control loops, the outer loop that get DC bus voltage feedback using PI anti-windup back calculation control method. This outer loop will generate a reference current for the inner loop that implement hysteresis control. The inner control loop will compare that reference curent with the source current obtained from the current sensor. Simulation and experimental results show that bus voltage is well-regulated under the load changes with 1% voltage ripple.

  14. Prediction of DC Corona Onset Voltage for Rod-Plane Air Gaps by a Support Vector Machine

    Science.gov (United States)

    Jin, Shuo; Ruan, Jiangjun; Du, Zhiye; Zhu, Lin; Shu, Shengwen

    2016-10-01

    This paper proposes a new method to predict the corona onset voltage for a rod-plane air gap, based on the support vector machine (SVM). Because the SVM is not limited by the size, dimension and nonlinearity of the samples, this method can realize accurate prediction with few training data. Only electric field features are chosen as the input; no geometric parameter is included. Therefore, the experiment data of one kind of electrode can be used to predict the corona onset voltages of other electrodes with different sizes. With the experimental data obtained by ozone detection technology, and experimental data provided by the reference, the efficiency of the proposed method is validated. Accurate predicted results with an average relative less than 3% are obtained with only 6 experimental data. supported by National Natural Science Foundation of China (No. 51477120)

  15. Control strategy and hardware implementation for DC–DC boost power circuit based on proportional–integral compensator for high voltage application

    Directory of Open Access Journals (Sweden)

    Sanjeevikumar Padmanaban

    2015-06-01

    Full Text Available For high-voltage (HV applications, the designers mostly prefer the classical DC–DC boost converter. However, it lacks due to the limitation of the output voltage by the gain transfer ratio, decreased efficiency and its requirement of two sensors for feedback signals, which creates complex control scheme with increased overall cost. Furthermore, the output voltage and efficiency are reduced due to the self-parasitic behavior of power circuit components. To overcome these drawbacks, this manuscript provides, the theoretical development and hardware implementation of DC–DC step-up (boost power converter circuit for obtaining extra output-voltage high-performance. The proposed circuit substantially improves the high output-voltage by voltage-lift technology with a closed loop proportional–integral controller. This complete numerical model of the converter circuit including closed loop P-I controller is developed in simulation (Matlab/Simulink software and the hardware prototype model is implemented with digital signal processor (DSP TMS320F2812. A detailed performance analysis was carried out under both line and load regulation conditions. Numerical simulation and its verification results provided in this paper, prove the good agreement of the circuit with theoretical background.

  16. VLSI Hybrid DC-DC Regulator

    OpenAIRE

    Cosp Vilella, Jordi; Martínez García, Herminio

    2015-01-01

    Hybrid DC-DC regulators are structures that combine both a linear voltage regulator and a switching DC-DC converter. The main objective of this hybrid topology is to converge, in a single circuit topology, the best of both alternatives: a small voltage output ripple, which is a common characteristic of linear regulator circuits, and good energy efficiency, as in switching alternatives. While the linear regulator fixes the required output voltage to a fixed value with negligible steady-state r...

  17. Square wave series voltage compensator with high frequency DC-DC converter; Compensador serie de tensao em onda quadrada com conversor CC-CC de alta frequencia

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Angelo Roberto Rodrigues Resende; Caetano, William Douglas; Pires, Igor Amariz; Silva, Arlete Vieira da [Centro Universitario de Belo Horizonte (UnBH), MG (Brazil)], e-mails: angelogalo2005@hotmail.com, wdouglasbh@gmail.com, igor_amariz@yahoo.com.br, arlete.silva@prof.unibh.br

    2011-07-01

    The square wave series voltage compensator is an equipment used to mitigate voltage sags. In the case of occurrence of a voltage disturbance, the compensator acts generating a square wave voltage to supply the missing voltage. The energy inserted for the compensation is taken from the electrical grid, by a linear source. The purpose of this paper is to present a switching shunt converter instead of a linear one, with the same output parameters in order to increase the power density. This efficiency is demonstrated by simulations. (author)

  18. Electric Insulation Detection Method for High-voltage Insulators

    Directory of Open Access Journals (Sweden)

    Wang Jiajun

    2013-07-01

    Full Text Available The principle of partial discharge detection is that through partial bridged discharge under high voltage electric field, it detects the inner air-filled cavity of high-voltage insulators. And it is a nondestructive detection method based on discharge magnitude to judge the insulation quality. The detecting system that adopts the partial discharge detection is more rigorous than testing system for electricity products, which must have small discharge capacity and higher sensitivity. This paper describes the principles of partial discharge detection and analysis insulation detection.

  19. Method to eliminate flux linkage DC component in load transformer for static transfer switch.

    Science.gov (United States)

    He, Yu; Mao, Chengxiong; Lu, Jiming; Wang, Dan; Tian, Bing

    2014-01-01

    Many industrial and commercial sensitive loads are subject to the voltage sags and interruptions. The static transfer switch (STS) based on the thyristors is applied to improve the power quality and reliability. However, the transfer will result in severe inrush current in the load transformer, because of the DC component in the magnetic flux generated in the transfer process. The inrush current which is always 2 ~ 30 p.u. can cause the disoperation of relay protective devices and bring potential damage to the transformer. The way to eliminate the DC component is to transfer the related phases when the residual flux linkage of the load transformer and the prospective flux linkage of the alternate source are equal. This paper analyzes how the flux linkage of each winding in the load transformer changes in the transfer process. Based on the residual flux linkage when the preferred source is completely disconnected, the method to calculate the proper time point to close each phase of the alternate source is developed. Simulation and laboratory experiments results are presented to show the effectiveness of the transfer method.

  20. Method to Eliminate Flux Linkage DC Component in Load Transformer for Static Transfer Switch

    Directory of Open Access Journals (Sweden)

    Yu He

    2014-01-01

    Full Text Available Many industrial and commercial sensitive loads are subject to the voltage sags and interruptions. The static transfer switch (STS based on the thyristors is applied to improve the power quality and reliability. However, the transfer will result in severe inrush current in the load transformer, because of the DC component in the magnetic flux generated in the transfer process. The inrush current which is always 2~30 p.u. can cause the disoperation of relay protective devices and bring potential damage to the transformer. The way to eliminate the DC component is to transfer the related phases when the residual flux linkage of the load transformer and the prospective flux linkage of the alternate source are equal. This paper analyzes how the flux linkage of each winding in the load transformer changes in the transfer process. Based on the residual flux linkage when the preferred source is completely disconnected, the method to calculate the proper time point to close each phase of the alternate source is developed. Simulation and laboratory experiments results are presented to show the effectiveness of the transfer method.

  1. Self-commutated high-voltage direct current transmission with DC circuit breakers. Backbone for the energy policy turnaround; Selbstgefuehrte Hochspannungs-Gleichstromuebertragung mit DC-Leistungsschalter. Rueckgrat fuer die Energiewende

    Energy Technology Data Exchange (ETDEWEB)

    Goerner, Raphael [ABB AG, Mannheim (Germany). Marketing und Vertrieb, Geschaeftsbereich Grid Systems

    2013-06-01

    The 'current war' between direct current and alternating current is extended by a new location. In the future, both technologies work together in order to provide a reliable power transmission in Germany and long-term in Europe. This is based on the self-guided high-voltage direct current transmission. In conjunction with direct current circuit breakers (DC circuit breaker) the power circuit breakers may help to make the transmission grids more flexible and to minimize losses.

  2. Fast and accurate method for computing ATC with voltage stability

    CERN Document Server

    Eidiani, M; Vahedi, E

    2002-01-01

    Order 889 mandated each control area to computer ATC (Available Transfer Capability) and post them on a communication system called the Open Access Same-time Information System (OASIS). Approaches of computing ATC can be divided into the following groups: Static and Dynamic methods. This paper presents a fast method for ATC calculations with voltage stability termination criteria. We use estimation of the determinant of Jacobian matrix for assessment of voltage stability. This method is compared with these methods: different between energy in SEP (Stable Equilibrium Point) and UEP (Unstable Equilibrium Point), ts index of Dr.Chiang and continuation power flow. The idea are demonstrated on 2, 3, 7 (CIGRE), 10, 30 (IEEE) and 145 bus (Iowa State University).

  3. High-Efficiency dc/dc Converter

    Science.gov (United States)

    Sturman, J.

    1982-01-01

    High-efficiency dc/dc converter has been developed that provides commonly used voltages of plus or minus 12 Volts from an unregulated dc source of from 14 to 40 Volts. Unique features of converter are its high efficiency at low power level and ability to provide output either larger or smaller than input voltage.

  4. 直流电压下的绝缘子质量评估%Study on Quality Assessment of Insulators Subjected to DC Voltages

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The failure of insulators under DC voltages is due to various factors like thermal runaway, ion migration, anode growth, surface erosion, cement growth etc.. However, the rate of failure is higher in polluted zones where surface erosion and puncturing of insulators due to ion migration can occur. Therefore, insulators have to be subjected to accelerated aging tests to simulate ion migration and to check their capability to withstand the stresses. Thermal runaway is also an important test. By carrying out Thermal runaway test at higher temperature, it may be possible to identify the good insulators. This paper presents the work carried out in order to asses the quality of DC insulators by Thermal runaway tests, Ion-migration tests and the measurement of the body resistance of the insulators. The voltage and temperature were varied during these tests in order to clearly identify the good insulators. The result will be useful for the design of insulators for the HVDC transmission system.

  5. Comparative Study of AC/DC High Voltage Transmissions%高压交直流输电比较研究

    Institute of Scientific and Technical Information of China (English)

    王红刚

    2011-01-01

    比较了高压交流输电和高压直流输电的差异,认为,输送同样的电能,高压直流输电损耗少的原因在于载流子在晶格势场中的能态低;由于载流子受到感应电场的作用,高压交流输电载流子在晶格势场中的能态将高于高压直流输电载流子的能态。不论高压交流输电还是高压直流输电都存在着趋肤效应,直流趋肤效应起源于载流子受到的霍尔电场力;交流趋肤效应起源于载流子除了受到霍尔电场力外,还受到了交变电场力的作用.%Comparing the differences between AC and DC high voltage transmissions,it is considered that the reason why the DC high voltage transmission has lower electrical loss in transmitting the same power is that its carriers have low energy state in lattice potential field.As the carriers being affected by induced electric field,carriers of AC will have higher energy state than that of DC in lattice potential field.No matter AC or DC high voltage transmission there is skin effect.The DC skin effect originates from Hall electric field force acting on the carriers,while the AC skin effect originates from not only Hall electric field,but the role of alternating electric field force.

  6. Digital Control of a High Voltage (2.5 kV) Bidirectional Flyback DC-DC Converter for Driving a Capacitive Incremental Actuator

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Maksimovic, Dragan; Zhang, Zhe;

    2016-01-01

    on the output high-voltage (HV) side. Experimental results verifying the bidirectional operation of a high voltage flyback converter are presented, using a 3 kV polypropylene film capacitor as the load. The energy loss distributions of the converter when 4 kV and 4.5 kV HV MOSFETs are used on HV side...

  7. Reduction of DC-link Capacitor in Case of Cascade Multilevel Converters by means of Reactive Power Control

    DEFF Research Database (Denmark)

    Gohil, Ghanshyamsinh Vijaysinh; Wang, Huai; Liserre, Marco

    2014-01-01

    A method to selectively control the amount of dc link voltage ripple by processing desired reactive power by a DC/DC converter in isolated AC/DC or AC/DC/AC system is proposed. The concept can reduce the dc link capacitors used for balancing the input and output power and thereby limiting...... the voltage ripple. It allows the use of smaller dc link capacitor and hence a longer lifetime and at the same time high power density and low cost can be achieved. The isolated DC/DC converter is controlled to process the desired reactive power in addition to the active power. The control system to achieve...

  8. Experimental investigation of dielectric barrier discharge plasma actuators driven by repetitive high-voltage nanosecond pulses with dc or low frequency sinusoidal bias

    Science.gov (United States)

    Opaits, Dmitry F.; Likhanskii, Alexandre V.; Neretti, Gabriele; Zaidi, Sohail; Shneider, Mikhail N.; Miles, Richard B.; Macheret, Sergey O.

    2008-08-01

    Experimental studies were conducted of a flow induced in an initially quiescent room air by a single asymmetric dielectric barrier discharge driven by voltage waveforms consisting of repetitive nanosecond high-voltage pulses superimposed on dc or alternating sinusoidal or square-wave bias voltage. To characterize the pulses and to optimize their matching to the plasma, a numerical code for short pulse calculations with an arbitrary impedance load was developed. A new approach for nonintrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the schlieren technique, burst mode of plasma actuator operation, and two-dimensional numerical fluid modeling. The force and heating rate calculated by a plasma model was used as an input to two-dimensional viscous flow solver to predict the time-dependent dielectric barrier discharge induced flow field. This approach allowed us to restore the entire two-dimensional unsteady plasma induced flow pattern as well as characteristics of the plasma induced force. Both the experiments and computations showed the same vortex flow structures induced by the actuator. Parametric studies of the vortices at different bias voltages, pulse polarities, peak pulse voltages, and pulse repetition rates were conducted experimentally. The significance of charge buildup on the dielectric surface was demonstrated. The charge buildup decreases the effective electric field in the plasma and reduces the plasma actuator performance. The accumulated surface charge can be removed by switching the bias polarity, which leads to a newly proposed voltage waveform consisting of high-voltage nanosecond repetitive pulses superimposed on a high-voltage low frequency sinusoidal voltage. Advantages of the new voltage waveform were demonstrated experimentally.

  9. Insulated DC-to-DC converter with wide input voltage range; Convertisseur continu-continu isole a large plage de tension d'entree: conception d'une alimentation 36 kW pour auxiliaire ferroviaire

    Energy Technology Data Exchange (ETDEWEB)

    Rieux, O.

    2000-11-15

    This thesis presents the research that has been carried out in the context of a collaboration contract between the FAIVELEY Transport company and the laboratoire d'Electrotechnique et d'Electronique Industrielle Laboratory. The goal of this research is the study of a converter that feeds a railway air conditioning unit, and that is fed by the overhead line voltage. It is an insulated DC-to-DC converter, of which input voltage varies from 2 to 5 kV, and output voltage is 600 V. This document introduces and justifies an original energy conversion principle. This principle is based on a series association of ZVS inverters, and a co-ordinated control that takes up the input voltage variations. This document also exposes detailed operation, and design rules applicable to converters based on this principle. Related studies are presented too, on such subjects as in situ reconnection of inverters for adapting to other overhead line types, or fault tolerance. Operation of such a converter has been studied by simulation, thus validating both the topology and the control modes. Experiments have also been carried out to check feasibility of a critical component of the structure: the saturable inductor. (author)

  10. Voltage-sharing Characteristics and Protection Value Setting of Modular Multilevel Converter at Static DC Charging State%MMC静态直流充电时电容均压特性研究和保护定值整定

    Institute of Scientific and Technical Information of China (English)

    李超; 唐志军; 林国栋; 邹焕雄; 翟博龙; 陈锦山

    2016-01-01

    A common problem in the static DC charging process of modular multilevel converter is voltage polarization.Some sub-modules”voltage sags even cause startup and shutdown repeatedly.In order to analyze the voltage-sharing characteristics of MMC,firstly,equivalent impedance of energy-absorbing source is introduced into the simulation model of sub-module;secondly,the mechanism of voltage polarization is studied based on the improved model;finally,a setting process of static DC charging tolerance time protection is proposed which can reduce the degree of voltage polarization.The static DC charging experiment and single tower test are conducted at Xiamen HVDC flexible transmission project and the results show consistence between simulation and experiment,which prove the feasibility of the improved simulation model of the sub-module,the mechanism analysis result of voltage polarization,the correction of static DC charging tolerance time protection value setting method.%模块化多电平换流器在静态直流充电时存在电容电压两极分化的问题,部分子模块甚至因电压跌落导致反复启动。先通过引入取能电源等效阻抗动态参数改进子模块等效模型,然后根据改进后模型仿真分析了电容电压两极分化的机理,最后在仿真基础上提出了静态直流充电耐受时间定值整定方法,通过优化保护定值降低电容电压两极分化程度。依托厦门柔性直流输电工程进行了静态直流充电和单个阀塔加压试验,试验结果与仿真结果基本一致,验证了所提子模块等效模型、电容电压两极分化机理分析和保护定值整定方法的正确性。

  11. Efficient Parametric Identification Method for High Voltage Pulse Transformers

    CERN Document Server

    Aguglia, D; Viarouge, P; Cros, J

    2014-01-01

    This paper presents a new identification method for a pulse transformer equivalent circuit. It is based on an analytical approximation of the frequency-domain impedance data derived from a no-load test with open-circuited secondary winding and only requires measurements of primary current and voltage without phase data. Compared with time consuming and complex methods based on off-line non-linear identification procedures, this simple method also gives an estimation of the error on the identified parameters. The method is validated on an existing pulse transformer.

  12. Correlation between Barrier Width, Barrier Height, and DC Bias Voltage Dependences on the Magnetoresistance Ratio in Ir-Mn Exchange Biased Single and Double Tunnel Junctions

    Science.gov (United States)

    Saito, Yoshiaki; Amano, Minoru; Nakajima, Kentaro; Takahashi, Shigeki; Sagoi, Masayuki; Inomata, Koichiro

    2000-10-01

    Dual spin-valve-type double tunnel junctions (DTJs) of Ir-Mn/CoFe/AlOx/Co90Fe10/AlOx/CoFe/Ir-Mn and spin-valve-type single tunnel junctions (STJs) of Ir-Mn/CoFe/AlOx/CoFe/Ni-Fe were fabricated using an ultrahigh vacuum sputtering system, conventional photolithography and ion-beam milling. The STJs could be fabricated with various barrier heights by changing the oxidization conditions during deposition and changing the annealing temperature after deposition, while the AlOx layer thickness remained unchanged. There was a correlation between barrier width, height estimated using Simmons’ expressions, and dc bias voltage dependence on the MR ratio. The VB dependence on the tunneling magnetoresistance (TMR) ratio was mainly related to the barrier width, and the decrease in the TMR ratio with increasing bias voltage is well explained, taking into account the spin-independent two-step tunneling via defect states in the barrier, as a main mechanism, at room temperature. Under optimized oxidization and annealing conditions, the maximum TMR ratio at a low bias voltage, and the dc bias voltage value at which the TMR ratio decreases in value by half (V1/2) were 42.4% and 952 mV in DTJs, and 49.0% and 425 mV in STJs, respectively.

  13. Research on Topologies of Voltage Balancers Applied in DC Micro-grid%面向直流微电网的电压平衡器拓扑结构研究

    Institute of Scientific and Technical Information of China (English)

    汪飞; 雷志方; 徐新蔚

    2016-01-01

    As an energy-saving efficient DC distribution form, bipolar DC bus has a great advantage in the low voltage DC power system, in which the voltage balancer plays an important role. A voltage balancer, on the one hand, achieves a conversion from unipolar bus to bipolar bus, and it also solves the problem of power imbalance between positive and negative polarity bus. This paper analyzed the existing research results of voltage balancer topologies in detail, and summed up the method of forming voltage balancers. Furthermore, new topologies were proposed, such as Cuk, Super-Sepic/Zeta and interleaved Buck/Boost type voltage balancers. Finally, the correctness of the proposed topologies were verified by simulations, and two phase interleaved Buck/Boost type voltage balancer experimental platform was used to verify its good bipolar bus distribution effect and the fine current sharing and dynamic characteristic of interleaved average current control strategy.%作为一种节能高效的直流配电形式,双极性直流母线配电在低压直流配电系统中具有较大的应用优势,电压平衡器在其中扮演着重要的角色。电压平衡器一方面实现了单极性配电向双极性配电的转化,另一方面也解决了正负极性母线间的功率不平衡问题。该文首先分析了现有的电压平衡器拓扑结构研究成果;然后归纳出了电压平衡器的形成方法,提出了Cuk型电压平衡器、Super-Sepic/Zeta型电压平衡器和交错并联 Buck/Boost 型电压平衡器;最后通过仿真验证了所提出拓扑结构的正确性,通过两相交错并联Buck/Boost型电压平衡器实验平台验证了所提出的交错采样交错平均电流控制策略良好的均流效果和动态响应速度以及平衡器优异的双极性母线配电效果。

  14. Circuit and Method for Communication Over DC Power Line

    Science.gov (United States)

    Krasowski, Michael J.; Prokop, Norman F.

    2007-01-01

    A circuit and method for transmitting and receiving on-off-keyed (OOK) signals with fractional signal-to-noise ratios uses available high-temperature silicon- on-insulator (SOI) components to move computational, sensing, and actuation abilities closer to high-temperature or high-ionizing radiation environments such as vehicle engine compartments, deep-hole drilling environments, industrial control and monitoring of processes like smelting, and operations near nuclear reactors and in space. This device allows for the networking of multiple, like nodes to each other and to a central processor. It can do this with nothing more than the already in-situ power wiring of the system. The device s microprocessor allows it to make intelligent decisions within the vehicle operational loop and to effect control outputs to its associated actuators. The figure illustrates how each node converts digital serial data to OOK 18-kHz in transmit mode and vice-versa in receive mode; though operations at lower frequencies or up to a megahertz are within reason using this method and these parts. This innovation s technique modulates a DC power bus with millivolt-level signals through a MOSFET (metal oxide semiconductor field effect transistor) and resistor by OOK. It receives and demodulates this signal from the DC power bus through capacitive coupling at high temperature and in high ionizing radiation environments. The demodulation of the OOK signal is accomplished by using an asynchronous quadrature detection technique realized by a quasi-discrete Fourier transform through use of the quadrature components (0 and 90 phases) of the carrier frequency as generated by the microcontroller and as a function of the selected crystal frequency driving its oscillator. The detected signal is rectified using an absolute-value circuit containing no diodes (diodes being non-operational at high temperatures), and only operational amplifiers. The absolute values of the two phases of the received signal

  15. ON THE CONVERGENCE OF AN APPROXIMATE PROXIMAL METHOD FOR DC FUNCTIONS

    Institute of Scientific and Technical Information of China (English)

    A. Moudafi; P-E. Maingé

    2006-01-01

    In this paper we prove the convergence of the approximate proximal method for DC functions proposed by Sun et al [6]. Our analysis also permits to treat the exact method.We then propose an interesting result in the case where the second component of the DC function is differentiable and provide some computational experiences which proved the efficiency of our method.

  16. Synchronverter-Enabled DC Power Sharing Approach for LVDC Microgrids

    DEFF Research Database (Denmark)

    Peyghami Akhuleh, Saeed; Davari, Pooya; Mokhtari, Hossein;

    2017-01-01

    In a classical ac Micro-Grid (MG), a common frequency exists for coordinating active power sharing among droop-controlled sources. Like the frequency droop method, a voltage based droop approach has been employed to control the converters in dc MGs. However, voltage variation due to the droop gains...... and line resistances causes poor power sharing and voltage regulation in dc MG, which in most cases are solved by a secondary controller using a communication network. To avoid such an infrastructure and its accompanied complications, this paper proposes a new droop scheme to control dc sources...... by introducing a small ac voltage superimposed onto the output dc voltage of converters. Therefore, dc sources can be coordinated together with the frequency of the ac voltage, without any communication network like Synchronous Generators (SGs) in conventional power systems. Small signal stability analysis...

  17. Chaos analysis and chaotic EMI suppression of DC-DC converters

    CERN Document Server

    Zhang, Bo

    2014-01-01

    Introduces chaos theory, its analytical methods and the means to apply chaos to the switching power supply design DC-DC converters are typical switching systems which have plenty of nonlinear behaviors, such as bifurcation and chaos. The nonlinear behaviors of DC-DC converters have been studied heavily over the past 20 years, yet researchers are still unsure of the practical application of bifurcations and chaos in switching converters. The electromagnetic interference (EMI), which resulted from the high rates of changes of voltage and current, has become a major design criterion in DC-DC co

  18. A novel method to measure the generated voltage of a ZnO nanogenerator

    Energy Technology Data Exchange (ETDEWEB)

    Heever, Stanley T van den; Buettner, Ulrich; Perold, Willem J, E-mail: tsvdh@sun.ac.za [Department of Electrical and Electronic Engineering, Stellenbosch University, Cnr Banghoek Road and Joubert Street, 7600, Stellenbosch (South Africa)

    2011-09-30

    A novel method to measure the output voltage of a zinc oxide nanowire nanogenerator is proposed. Various tests are performed to verify that the output voltage does indeed originate from the nanogenerator and not from environmental noise. Although noise does influence the output voltage measurements, the output voltage is easily distinguishable from the measured noise. It is also shown that the method can be used to determine the internal resistance of the nanogenerator by measuring the output voltage over different output resistors.

  19. Modeling and Design of DC Boost and AC Side Voltage Controllers in Asymmetrical Γ-Source Inverter

    Directory of Open Access Journals (Sweden)

    Seyed Mahyar Mehdizadeh Moghadam

    2014-07-01

    Full Text Available In this paper a control system is proposed to simultaneously control the voltage boost and output voltage of assymetrical Γ-Source Inverters. Dynamic model of the system is used to design the controllers. Voltage boost on assymetrical Γ-Source Inverters is done by voltage control of impedance network capacitor and the regulation of inverter shoot through duty cycle. Since the stability margin of the system is low due to the right half plane zero in its dynamic model, the design of fast control system is impossible therefore a nonlinear feedforward control loop is used to faster the control system performance. Linear control system is used to control the AC-side in synchrony reference frame such that the AC voltage control system regulates the output voltage by means of modulation index regulation. The proposed control system performance is investigated by simulation in MATLAB/Simulink

  20. Capacitor Voltages Measurement and Balancing in Flying Capacitor Multilevel Converters Utilizing a Single Voltage Sensor

    DEFF Research Database (Denmark)

    Farivar, Glen; Ghias, Amer M. Y. M.; Hredzak, Branislav

    2017-01-01

    This paper proposes a new method for measuring capacitor voltages in multilevel flying capacitor (FC) converters that requires only one voltage sensor per phase leg. Multiple dc voltage sensors traditionally used to measure the capacitor voltages are replaced with a single voltage sensor at the ac...... side of the phase leg. The proposed method is subsequently used to balance the capacitor voltages using only the measured ac voltage. The operation of the proposed measurement and balancing method is independent of the number of the converter levels. Experimental results presented for a five-level FC...

  1. Modeling and Design of DC Boost and AC Side Voltage Controllers in Asymmetrical Γ-Source Inverter

    OpenAIRE

    2014-01-01

    In this paper a control system is proposed to simultaneously control the voltage boost and output voltage of assymetrical Γ-Source Inverters. Dynamic model of the system is used to design the controllers. Voltage boost on assymetrical Γ-Source Inverters is done by voltage control of impedance network capacitor and the regulation of inverter shoot through duty cycle. Since the stability margin of the system is low due to the right half plane zero in its dynamic model, the design of fast contro...

  2. Advanced DC/DC converters

    CERN Document Server

    Luo, Fang Lin

    2003-01-01

    INTRODUCTIONHistorical ReviewMultiple Quadrant ChoppersPump CircuitsDevelopment of DC/DC Conversion TechniqueCategorize Prototypes and DC/DC Converters Family TreeVOLTAGE-LIFT CONVERTERSIntroductionSeven Self-Lift ConvertersPositive Output Luo-ConvertersNegative Output Luo-ConvertersModified Positive Output Luo-Converters Double Output Luo-ConvertersPOSITIVE OUTPUT SUPER-LIFT LUO-CONVERTERS IntroductionMain SeriesAdditional SeriesEnhanced Series Re-Enhanced Series Multiple-Enhanced Series Summary of Positive Output

  3. A Coordinated Control for Photovoltaic Generators and Energy Storages in Low-Voltage AC/DC Hybrid Microgrids under Islanded Mode

    Directory of Open Access Journals (Sweden)

    Yao Liu

    2016-08-01

    Full Text Available The increasing penetration of renewable generators can be a significant challenge due to the fluctuation of their power generation. Energy storage (ES units are one solution to improve power supply quality and guarantee system stability. In this paper, a hybrid microgrid is built based on photovoltaic (PV generator and ES; and coordinated control is proposed and developed to achieve power management in a decentralized manner. This control scheme contains three different droop strategies according to characteristics of PV and ES. First, the modified droop control is proposed for PV, which can take full utilization of renewable energy and avoid regulating output active power frequently. Second, to maintain the direct current (DC bus voltage stability, a novel droop control incorporating a constant power band is presented for DC-side ES. Third, a cascade droop control is designed for alternating current (AC-side ES. Thus, the ES lifetime is prolonged. Moreover, interlinking converters (ICs provide a bridge between AC/DC buses in a hybrid microgrid. The power control of IC is enabled when the AC- or DC-side suffer from active power demand shortage. In particular, if the AC microgrid does not satisfy the reactive power demand, IC then acts as a static synchronous compensator (STATCOM. The effectiveness of the proposed strategies is verified by simulations.

  4. Design and Testing of a Low Cost PID Controller Combined with Inverse Derivative Control Action and Its Application in Voltage Control Systems of DC Generator

    Directory of Open Access Journals (Sweden)

    Subrata CHATTOPADHYAY

    2008-01-01

    Full Text Available A single PID controller in a process control loop may suffer from high frequency oscillations without offset or low frequency oscillation with offset. An inverse derivative control action can eliminate both of these errors. In the present paper, a low cost operational amplifier based PID controller with inverse derivative control action has been described. Its transfer function has been derived and is found to be identical with the form already derived by other workers. It has been tested with a process plant analogue and implemented in the voltage control system of a DC generator. Its transfer function along with its characteristics in a process plant analogue and the load characteristics of DC generator with and without this controller have been determined experimentally and reported in this paper.

  5. Atmospheric dc discharges with miniature gas flow as microplasma generation method

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, Takuma; Hamada, Shuhei; Ibuka, Shinji; Yasuoka, Koichi; Ishii, Shozo [Department of Electrical and Electronic Engineering, Tokyo Institute of Technology, Tokyo 152-8552 (Japan)

    2005-06-07

    An atmospheric microplasma is generated by direct-current (dc) discharge in air with a miniature gas flow through a nozzle, which limits plasma volume. Two discharge modes appear in a nozzle-to-mesh electrode system with helium or argon. One is a repetitive pulsed discharge with a current of 10-30 mA and a short pulse width. The fast pulsed current is powered by electric charges stored in the parasitic capacitance, which depends on the spatial arrangement of the electrodes and the power leads. The pulsed discharge makes it possible to develop a discharge scheme for microplasma generation without a high-voltage pulse generator. The other is a sustained dc discharge, which develops with increasing applied voltage. In the case of helium, a glow discharge configuration is observed with a positive column and a layered structure near the cathode. The length of the positive column is affected by electrode separation and gas flow rate.

  6. Ideas on DC-DC Converters for Delivery of Low Voltage and High Currents for the SLHC / ILC Detector Electronics in Magnetic field and Radiation environments

    CERN Document Server

    Dhawan, Satish; Neal, H; Sumner, R; Weber, M; Weber, R

    2007-01-01

    For more efficient power transport to the electronics embedded inside large colliding beam detectors, we explore the feasibility of supplying 48 Volts DC and using local DCDC conversion to 2 V (or lower, depending upon on the lithography of the embedded electronics) using switch mode regulators located very close to the front end electronics. These devices will be exposed to high radiation and high magnetic fields, 10 – 100 Mrads and 2 - 4 Tesla at the SLHC, and 20 Krads and 6 Tesla at the ILC.

  7. An automatic method to analyze the Capacity-Voltage and Current-Voltage curves of a sensor

    CERN Document Server

    Matorras Cuevas, Pablo

    2017-01-01

    An automatic method to perform Capacity versus voltage analysis for all kind of silicon sensor is provided. It successfully calculates the depletion voltage to unirradiated and irradiated sensors, and with measurements with outliers or reaching breakdown. It is built using C++ and using ROOT trees with an analogous skeleton as TRICS, where the data as well as the results of the ts are saved, to make further analysis.

  8. System and method for floating-substrate passive voltage contrast

    Science.gov (United States)

    Jenkins, Mark W.; Cole, Jr., Edward I.; Tangyunyong, Paiboon; Soden, Jerry M.; Walraven, Jeremy A.; Pimentel, Alejandro A.

    2009-04-28

    A passive voltage contrast (PVC) system and method are disclosed for analyzing ICs to locate defects and failure mechanisms. During analysis a device side of a semiconductor die containing the IC is maintained in an electrically-floating condition without any ground electrical connection while a charged particle beam is scanned over the device side. Secondary particle emission from the device side of the IC is detected to form an image of device features, including electrical vias connected to transistor gates or to other structures in the IC. A difference in image contrast allows the defects or failure mechanisms be pinpointed. Varying the scan rate can, in some instances, produce an image reversal to facilitate precisely locating the defects or failure mechanisms in the IC. The system and method are useful for failure analysis of ICs formed on substrates (e.g. bulk semiconductor substrates and SOI substrates) and other types of structures.

  9. Design and development of DC high current sensor using Hall-Effect method

    Science.gov (United States)

    Dewi, Sasti Dwi Tungga; Panatarani, C.; Joni, I. Made

    2016-02-01

    This paper report a newly developed high DC current sensor by using a Hall effect method and also the measurement system. The Hall effect sensor receive the magnetic field generated by a current carrying conductor wire. The SS49E (Honeywell) magnetoresistive sensor was employed to sense the magnetic field from the field concentrator. The voltage received from SS49E then converted into digital by using analog to digital converter (ADC-10 bit). The digital data then processed in the microcontroller to be displayed as the value of the electric current in the LCD display. In addition the measurement was interfaced into Personal Computer (PC) using the communication protocols of RS232 which was finally displayed in real-time graphical form on the PC display. The performance test on the range ± 40 Ampere showed that the maximum relative error is 5.26%. It is concluded that the sensors and the measurement system worked properly according to the design with acceptable accuracy.

  10. Control and dynamic analysis of a parallel-connected single active bridge DC-DC converter for DC-grid wind farm application

    DEFF Research Database (Denmark)

    Park, Kiwoo; Chen, Zhe

    2015-01-01

    This study presents a control strategy and its dynamic analysis of a high-power dc-dc converter, which is constructed with the parallel-connected single active bridge (SAB) dc-dc converters for dc-grid wind farm applications. The structural and operational characteristics of the SAB dc-dc converter...... have several advantages for high-power applications, and the modular concept of the parallel-connected converter is highly beneficial especially for offshore wind farm applications in terms of maintenance cost and fault tolerance. To justify the feasibility of the parallel-connected SAB dc-dc converter...... for dc-grid wind farm applications, an input voltage control method based on the PI control will be introduced and the dynamics of the overall system will be analysed. The analysis results are to be verified by means of simulations and experiments....

  11. Efficient Design in a DC to DC Converter Unit

    Science.gov (United States)

    Bruemmer, Joel E.; Williams, Fitch R.; Schmitz, Gregory V.

    2002-01-01

    Space Flight hardware requires high power conversion efficiencies due to limited power availability and weight penalties of cooling systems. The International Space Station (ISS) Electric Power System (EPS) DC-DC Converter Unit (DDCU) power converter is no exception. This paper explores the design methods and tradeoffs that were utilized to accomplish high efficiency in the DDCU. An isolating DC to DC converter was selected for the ISS power system because of requirements for separate primary and secondary grounds and for a well-regulated secondary output voltage derived from a widely varying input voltage. A flyback-current-fed push-pull topology or improved Weinberg circuit was chosen for this converter because of its potential for high efficiency and reliability. To enhance efficiency, a non-dissipative snubber circuit for the very-low-Rds-on Field Effect Transistors (FETs) was utilized, redistributing the energy that could be wasted during the switching cycle of the power FETs. A unique, low-impedance connection system was utilized to improve contact resistance over a bolted connection. For improved consistency in performance and to lower internal wiring inductance and losses a planar bus system is employed. All of these choices contributed to the design of a 6.25 KW regulated dc to dc converter that is 95 percent efficient. The methodology used in the design of this DC to DC Converter Unit may be directly applicable to other systems that require a conservative approach to efficient power conversion and distribution.

  12. Performance analysis of active damped small DC-link capacitor based drive for unbalanced input voltage supply

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Munk-Nielsen, Stig

    2011-01-01

    A small DC-link capacitor based drive is presented in this paper. The drive shows negative impedance instability at operating points with high power load. A phase portrait is presented for input filter states which exhibit a limit cycle. When the drive is operated with unbalanced input supply...

  13. Pole placement method of controlling chaos in DC-DC buck converters

    Institute of Scientific and Technical Information of China (English)

    Zou Yan-Li; Luo Xiao-Shu; Chen Guan-Rong

    2006-01-01

    Based on the mechanism for the generation of chaos in a buck converter, a pole placement method is proposed and applied to controlling the chaos in a circuit. The control circuit is designed and tested. Numerical calculation and circuit implementation demonstrate the validity of this chaos control method.

  14. THE SYSTEM OF CONTACT SYSTEM POWER SUPPLY OF DC NETWORK WITH A LONGITUDINAL LINE OF HIGH VOLTAGE

    Directory of Open Access Journals (Sweden)

    Yu. P. Honcharov

    2008-02-01

    Full Text Available The power supply system of a contact network using a longitudinal line with points of communication without transformer is considered. The approach allowing to facilitate power filters and the way of switching of in-series connected semiconductor switches with fixing a voltage on them are offered.

  15. Scalable single point power extraction for compact mobile and stand-alone solar harvesting power sources based on fully printed organic photovoltaic modules and efficient high voltage DC/DC conversion

    DEFF Research Database (Denmark)

    Garcia Valverde, Rafael; Villarejo, José A.; Hösel, Markus

    2015-01-01

    Patterns for fully printed polymer solar cells are presented that inherently enable scaling of the power output with single point electrical energy connection is presented. Connection is made to only one end of the printed foil that can be rolled out for light energy harvesting. The power level...... is simply increased/decreased by increasing/decreasing the length of the foil with a corresponding increase/decrease in operating voltage. The current flow runs in both directions along the printed foil thus alleviating the need for post process addition of complex busbar topologies. The power conversion...... takes place in a HVDC–DC converter that is tailored specifically for operation with polymer solar cells by regulation on the input side. The system charges a lithium-polymer battery thus enabling storage of 82 Wh for a printed OPV foil measuring 0.305 m×9 m having a nominal power output of at least 15 W...

  16. Generation of reference dc currents at 1 nA level with the capacitance-charging method

    CERN Document Server

    Callegaro, Luca; D'Elia, Vincenzo; Galliana, Flavio

    2013-01-01

    The capacitance-charging method is a well-established and handy technique for the generation of dc current in the 100 pA range or lower. The method involves a capacitance standard and a sampling voltmeter, highly stable devices easy to calibrate, and it is robust and insensitive to the voltage burden of the instrument being calibrated. We propose here a range extender amplifier, which can be employed as a plug-in component in existing calibration setups, and allows the generation of currents in the 1 nA range. The extender has been employed in the INRIM setup and validated with two comparisons at 100 pA and 1 nA current level. The calibration accuracy achieved on a top-class instrument is 10 ppm at 1 nA.

  17. Modeling and Simulation of DC Power Electronics Systems Using Harmonic State Space (HSS) Method

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

    2015-01-01

    For the efficiency and simplicity of electric systems, the dc based power electronics systems are widely used in variety applications such as electric vehicles, ships, aircrafts and also in homes. In these systems, there could be a number of dynamic interactions between loads and other dc...... based on the state-space averaging and generalized averaging, these also have limitations to show the same results as with the non-linear time domain simulations. This paper presents a modeling and simulation method for a large dc power electronic system by using Harmonic State Space (HSS) modeling....... Through this method, the required computation time and CPU memory for large dc power electronics systems can be reduced. Besides, the achieved results show the same results as with the non-linear time domain simulation, but with the faster simulation time which is beneficial in a large network....

  18. High Bandwidth Zero Voltage Injection Method for Sensorless Control of PMSM

    DEFF Research Database (Denmark)

    Ge, Xie; Lu, Kaiyuan; Kumar, Dwivedi Sanjeet

    2014-01-01

    High frequency signal injection is widely used in PMSM sensorless control system for low speed operations. The conventional voltage injection method often needs filters to obtain particular harmonic component in order to estimate the rotor position; or it requires several voltage pulses to be inj...... in a fast current regulation performance. Injection of zero voltage also minimizes the inverter voltage error effects caused by the dead-time.......High frequency signal injection is widely used in PMSM sensorless control system for low speed operations. The conventional voltage injection method often needs filters to obtain particular harmonic component in order to estimate the rotor position; or it requires several voltage pulses...... to be injected before the position may be estimated. In this paper, a single pulse zero voltage injection method is proposed. The rotor position is directly estimated from the current ripple at half of the switching frequency. No machine parameters are needed and using of filters is avoided. This results...

  19. System and Method for Determining Rate of Rotation Using Brushless DC Motor

    Science.gov (United States)

    Howard, David E. (Inventor); Smith, Dennis A. (Inventor)

    2000-01-01

    A system and method are provided for measuring rate of rotation. A brushless DC motor is rotated and produces a back electromagnetic force (emf) on each winding thereof. Each winding's back-emf is squared. The squared outputs associated with each winding are combined, with the square root being taken of such combination, to produce a DC output proportional only to the rate of rotation of the motor's shaft.

  20. Separation of nanoparticles by a nano-orifice based DC-dielectrophoresis method in a pressure-driven flow.

    Science.gov (United States)

    Zhao, Kai; Peng, Ran; Li, Dongqing

    2016-12-07

    A novel DC-dielectrophoresis (DEP) method employing a pressure-driven flow for the continuous separation of micro/nano-particles is presented in this paper. To generate the DEP force, a small voltage difference is applied to produce a non-uniformity of the electric field across a microchannel via a larger orifice of several hundred microns on one side of the channel wall and a smaller orifice of several hundred nanometers on the opposite channel wall. The particles experience a DEP force when they move with the flow through the vicinity of the small orifice, where the strongest electrical field gradient exists. Experiments were conducted to demonstrate the separation of 1 μm and 3 μm polystyrene particles by size by adjusting the applied electrical potentials. In order to separate smaller nanoparticles, the electrical conductivity of the suspending solution is adjusted so that the polystyrene nanoparticles of a given size experience positive DEP while the polystyrene nanoparticles of another size experience negative DEP. Using this method, the separation of 51 nm and 140 nm nanoparticles and the separation of 140 nm and 500 nm nanoparticles were demonstrated. In comparison with the microfluidic DC-DEP methods reported in the literature which utilize hurdles or obstacles to induce the non-uniformity of an electric field, a pair of asymmetrical orifices on the channel side walls is used in this method to generate a strong electrical field gradient and has advantages such as capability of separating nanoparticles, and locally applied lower electrical voltages to minimize the Joule heating effect.

  1. Study on Test Method for Low Frequency Noise of Optoelectronic Coupled Device in DC/DC Converter%DC/DC电源用光电耦合器低频噪声测试方法研究

    Institute of Scientific and Technical Information of China (English)

    包军林; 孙明; 庄奕琪; 于鹏; 任泽亮

    2012-01-01

    Optoelectronic coupled device (OCD) is a key element of DC/DC converter. The random increase of low frequency noise (LFN) is one of the main failure modes of DC/DC converter. Effective test method and standard for LFN of photoelectric coupler are absent in China. In this paper, characteristics of low frequency noise in OCD and its generation mechanism were investigated in detail. Bias circuit, equipment and method for LFN measurement were proposed. Experimental results from OCD 4N47 in DC/DC converter demonstrated that the proposed method could be used for accurate measurement of low frequency noise of OCDs, providing an effective approach to evaluating typical faults and system suitability of optoelectronic coupler for DC/DC converter.%光电耦合器是DC/DC电源的关键器件,光电耦合器低频噪声的随机增大是该类电源主要失效模式之一.目前,国内尚未形成光电耦合器低频噪声的有效测试方法,更未建立相关标准.文章详细分析了光电耦合器低频噪声特性及产生机理,提出了其低频噪声测试的偏置电路、测试设备和测试方法.针对用于DC/DC电源的典型光电耦合器(4N47)的实测结果表明,该方法能够准确测试光电耦合器的低频噪声,为DC/DC电源用光电耦合器的系统适用性和典型故障提供了一种有效的评估方法.

  2. A resonant dc-dc power converter assembly

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor...... of the second resonant DC-DC power converter are configured for magnetically coupling the first and second resonant DC-DC power converters to each other to forcing substantially 180 degrees phase shift, or forcing substantially 0 degree phase shift, between corresponding resonant voltage waveforms of the first...... and second resonant DC-DC power converters. The first and second inductors are corresponding components of the first and second resonant DC-DC power converters....

  3. Effects of adsorbed proteins, an antifouling agent and long-duration DC voltage pulses on the impedance of silicon-based neural microelectrodes.

    Science.gov (United States)

    Sommakia, Salah; Rickus, Jenna L; Otto, Kevin J

    2009-01-01

    The successful use of implantable neural microelectrodes as neuroprosthetic devices depends on the mitigation of the reactive tissue response of the brain. One of the factors affecting the ultimate severity of the reactive tissue response and the in vivo electrical properties of the microelectrodes is the initial adsorption of proteins onto the surface of the implanted microelectrodes. In this study we quantify the increase in microelectrode impedance magnitude at physiological frequencies following electrode immersion in a 10% bovine serum albumin (BSA) solution. We also demonstrate the efficacy of a common antifouling molecule, poly(ethylene glycol) (PEG), in preventing a significant increase in microelectrode impedance. In addition, we show the feasibility of using long-duration DC voltage pulses to remove adsorbed proteins from the microelectrode surface.

  4. Frequency Domain Modeling and Simulation of DC Power Electronic Systems Using Harmonic State Space Method

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Blaabjerg, Frede

    2016-01-01

    For the efficiency and simplicity of electric systems, the dc power electronic systems are widely used in a variety of applications such as electric vehicles, ships, aircraft and also in homes. In these systems, there could be a number of dynamic interactions and frequency coupling between network...... with different switching frequency or harmonics from ac-dc converters makes that harmonics and frequency coupling are both problems of ac system and challenges of dc system. This paper presents a modeling and simulation method for a large dc power electronic system by using Harmonic State Space (HSS) modeling...... and loads and other converters. Hence, time-domain simulations are usually required to consider such a complex system behavior. However, simulations in the time-domain may increase the calculation time and the utilization of computer memory. Furthermore, frequency coupling driven by multiple converters...

  5. A new method for speed control of a DC motor using magnetorheological clutch

    Science.gov (United States)

    Nguyen, Quoc Hung; Choi, Seung-Bok

    2014-03-01

    In this research, a new method to control speed of DC motor using magnetorheological (MR) clutch is proposed and realized. Firstly, the strategy of a DC motor speed control using MR clutch is proposed. The MR clutch configuration is then proposed and analyzed based on Bingham-plastic rheological model of MR fluid. An optimal designed of the MR clutch is then studied to find out the optimal geometric dimensions of the clutch that can transform a required torque with minimum mass. A prototype of the optimized MR clutch is then manufactured and its performance characteristics are experimentally investigated. A DC motor speed control system featuring the optimized MR clutch is designed and manufactured. A PID controller is then designed to control the output speed of the system. In order to evaluate the effectiveness of the proposed DC motor speed control system, experimental results of the system such as speed tracking performance are obtained and presented with discussions.

  6. Power Balance Control in an AC/DC/AC Converter for Regenerative Braking in a Two-Voltage-Level Flywheel-Based Driveline

    Directory of Open Access Journals (Sweden)

    Janaína G. Oliveira

    2011-01-01

    Full Text Available The integration of a flywheel as a power handling can increase the energy storage capacity and reduce the number of battery charge/discharge cycles. Furthermore, the ability of recovering energy of the vehicle during breaking can increase the system efficiency. The flywheel-based all-electric driveline investigated here has its novelty in the use of a double-wound flywheel motor/generator, which divides the system in two different voltage levels, enhancing the efficiency of the electric driveline. The connection of two AC electrical machines (i.e., the flywheel and the wheel motor with different and variable operation frequency is challenging. A power matching control applied to an AC/DC/AC converter has been implemented. The AC/DC/AC converter regenerates the electric power converted during braking to the flywheel machine, used here as power handling device. By controlling the power balance, the same hardware can be used for acceleration and braking, providing the reduction of harmonics and robust response. A simulation of the complete system during braking mode has been performed both in Matlab and Simulink, and their results have been compared. The functionality of the proposed control has been shown and discussed, with full regeneration achieved. A round-trip efficiency (wheel to wheel higher than 80% has been obtained.

  7. 基于电力电子调压电路的直流不停电融冰技术%Study of DC Ice-melting Without Power Cut Technology Based on Power Electronic Voltage-regulating Circuits

    Institute of Scientific and Technical Information of China (English)

    宋洁莹; 周飞; 拜润清; 蔡林海; 荆平

    2014-01-01

    Ice-coating of transmission lines every year in winter seriously affects reliable operation of power grids in China. Present electrical ice-melting methods all require power interruption, which brings negative effects to power grid. To address this issue, principles and feasibility of DC and AC ice-melting without power cut methods are analyzed, a new DC ice-melting without power cut method is proposed, and its circuit structure and capacity requirements are analyzed. At last, a model of the ice-melting device under PSCAD is built and its principles and functions are verified by simulation. The DC ice-melting without power cut device based on power electronic voltage-regulating circuits has high working efficiency and little influence upon regular power supplying.%我国冬季出现的输电线路覆冰的情况严重影响电力系统的可靠运行,现有的电力融冰均需停电进行,对系统影响较大。针对这个问题,分析交、直流不停电融冰的原理及可行性,提出一种新型的不停电直流融冰方法,对其电路结构和所需容量进行分析,并建立不停电融冰装置仿真模型,进行原理和功能验证。基于电力电子调压电路的不停电直流融冰装置具有融冰效率高且不影响线路供电的优点。

  8. Method for Estimating Low-Frequency Return Current of DC Electric Railcar

    Science.gov (United States)

    Hatsukade, Satoru

    The Estimation of the harmonic current of railcars is necessary for achieving compatibility between train signaling systems and railcar equipment. However, although several theoretical analyses methods for estimating the harmonic current of railcars using switching functions exist, there are no theoretical analysis methods estimating a low-frequency current at a frequency less than the power converter's carrier frequency. This paper describes a method for estimating the spectrum (frequency and amplitude) of the low-frequency return current of DC electric railcars. First, relationships between the return current and characteristics of the DC electric railcars, such as mass and acceleration, are determined. Then, the mathematical (not numerical) calculation results for low-frequency current are obtained from the time-current curve for a DC electric railcar by using Fourier series expansions. Finally, the measurement results clearly show the effectiveness of the estimation method development in this study.

  9. An Experimental Study on Voltage Compensation Method using Autonomous Decentralized Control of Distributed Generators

    Science.gov (United States)

    Tanaka, Shunsuke; Suzuki, Hirokazu

    When many distributed generators (DGs) are connected to a distribution line, the upward power flow from DGs causes the difficulty in line voltage regulation. As the countermeasure, we propose several methods to control the line voltage by use of DGs' reactive power outputs. These methods using only DGs' reactive power are implemented in an autonomous decentralized way. DGs with the function to estimate the line impedance provide the power system with reactive power according to the estimated impedance value, and regulate the line voltage. We evaluate the effect of the proposed methods for voltage compensation by experimental studies using commercial grid-connected inverters for PV system.

  10. Active Damping Control Methods for Three-Phase Slim DC-link Drive System

    DEFF Research Database (Denmark)

    Yang, Feng; Wang, Dong; Blaabjerg, Frede

    2017-01-01

    -choke. However, such drive system suffers from the potential instability issue, due to the negative incremental impedance characteristic caused by the constant power load behavior of the motor drive system, and the influence by the reduced capacitance. Therefore, active damping methods are very important...... for stabilizing such slim dc-link drives together with the benefit of low cost and high flexibility. This paper gives an overview of the state-of-the-art active damping methods for the three-phase slim dc-link drive. The main pros and cons of each method are identified. The theoretical comparison is validated...

  11. Improvement in nano-hardness and corrosion resistance of low carbon steel by plasma nitriding with negative DC bias voltage

    Science.gov (United States)

    Alim, Mohamed Mounes; Saoula, Nadia; Tadjine, Rabah; Hadj-Larbi, Fayçal; Keffous, Aissa; Kechouane, Mohamed

    2016-10-01

    In this work, we study the effect of plasma nitriding on nano-hardness and corrosion resistance of low carbon steel samples. The plasma was generated through a radio-frequency inductively coupled plasma source. The substrate temperature increased (by the self-induced heating mechanism) with the treatment time for increasing negative bias voltages. X-rays diffraction analysis revealed the formation of nitride phases (ɛ-Fe2-3N and γ'-Fe4N) in the compound layer of the treated samples. A phase transition occurred from 3.5 kV to 4.0 kV and was accompanied by an increase in the volume fraction of the γ'-Fe4N phase and a decrease in that of the ɛ-Fe2-3N phase. Auger electron spectroscopy revealed a deep diffusion of the implanted nitrogen beyond 320 nm. The nano-hardness increased by ~400% for the nitrogen-implanted samples compared to the untreated state, the nitride phases are believed to participate to the hardening. Potentiodynamic polarization measurements revealed that the plasma nitriding has improved the corrosion resistance behavior of the material. When compared to the untreated state, the sample processed at 4.0 kV exhibits a shift of +500 mV and a reduction to 3% in its corrosion current. These results were obtained for relatively low bias voltages and short treatment time (2 h).

  12. Effect of bleeding method and low voltage electrical stimulation on ...

    African Journals Online (AJOL)

    None the less, personal observations would recommend the use of TS due ... Electrical stimulation also had no effect on the Warner Bratzler shear force values in the fillet. It can be concluded that low voltage ES has no advantage pertaining to ...

  13. A METHOD FOR DETERMINING LOCATION OF VOLTAGE FLUCTUATIONS SOURCE IN ELECTRIC GRID

    Directory of Open Access Journals (Sweden)

    G.A. Senderovich

    2016-06-01

    Full Text Available Purpose. The purpose of work is development of a method of definition of the location of a source of fluctuations of voltage. Methodology. The reasons of emergence of fluctuations of voltage at an arrangement of a source both in power lines, and in the consumer's networks, are connected with changes of consumption and active and reactive capacities. As criterion for definition of the location of a source of fluctuations of voltage we choose change of size of the active power received by reception substation on equivalent communication with system. The source of fluctuations of voltage is external for the consumer if emergence of fluctuations of voltage leads to the coordinated changes of tension and consumed in the area of active power that corresponds to a condition of the positive regulating effect of active loading on voltage (1. The source of fluctuations of voltage is internal for the consumer if emergence of fluctuations of voltage leads to counter changes of tension and consumed in the area of active power that resembles a condition of the negative regulating effect of active loading on voltage superficially (6. Results. The method of definition of the location of a source of fluctuations of voltage in an electric network which, works by the principle of an assessment of correlation of change of power and tension in a power supply network is developed. The method allows to consider shift between extrema of curves of change of voltage of U(t and power of Pload(t. Originality. The method of definition of an arrangement of a source of fluctuations of voltage is developed. Practical value. The answer to this question where the source of fluctuations of voltage (in the territory of the consumer is located or in an external network confirmed with the determined calculation, can form a basis of the expert opinion for the solution of legal disputes at an assessment of the damages caused by poor quality of electric energy.

  14. 基于电弧电压的混合型直流断路器%Hybrid DC Breaker Based on Arc Voltage

    Institute of Scientific and Technical Information of China (English)

    吕玮; 方太勋; 杨浩; 杨兵; 王宇; 石巍

    2015-01-01

    The hybrid direct current(DC) breaker has good static characteristics and good dynamic characteristics.The multi-terminal high-voltage direct current (HVDC) transmission network is largely dependent on the development of DC circuit breaker technology. This paper presents a hybrid DC circuit breaker based on arc voltage, and derives mathematical relationship of current-commutation.Simulating the key part-high speed switch by the electro-magnetic repulsion mechanism is performed using finite element analysis.A 1 kA/1 5 kV hybrid DC breaker is designed based on the above research,and the test results show that the prototype”s arc maximum current-commutation capacity is 3 kA.The process of current transfer from high-speed switch to solid state switch accords with the exponential function,and is consistent with theoretical derivation.The prototype can break the short-circuit current less than 10 kA within 5 ms,and the break time depends primarily on high-speed switch and arc voltage.%混合型直流断路器同时具有传统机械开关良好的静态特性和固态开关无弧快速关断的动态特性,多端直流输电网络很大程度上依赖于直流断路器技术的发展。文中提出了一种基于电弧电压的混合型直流断路器,推导了电流换流物理过程的数学关系。通过有限元分析软件,进行了关键部件———电磁斥力机构高速开关的仿真计算。在以上基础上进行了1 kA/15 kV 直流断路器样机的设计研制,试验结果表明,该样机的电弧最大换流能力为3 kA,电流从高速开关向固态开关转移的过程呈指数关系,与理论推导相符。该样机能够在5 ms 内分断10 kA 短路电流,分断时间主要取决于高速开关开断速度以及电弧电压大小。

  15. Comparison of pulsating DC and DC power air-water plasma jet: A method to decrease plume temperature and increase ROS

    Science.gov (United States)

    Liu, K.; Hu, H.; Lei, J.; Hu, Y.; Zheng, Z.

    2016-12-01

    Most air-water plasma jets are rich in hydroxyl radicals (•OH), but the plasma has higher temperatures, compared to that of pure gas, especially when using air as working gas. In this paper, pulsating direct current (PDC) power was used to excite the air-water plasma jet to reduce plume temperature. In addition to the temperature, other differences between PDC and DC plasma jets are not yet clear. Thus, comparative studies of those plasmas are performed to evaluate characteristics, such as breakdown voltage, temperature, and reactive oxygen species. The results show that the plume temperature of PDC plasma is roughly 5-10 °C lower than that of DC plasma in the same conditions. The •OH content of PDC is lower than that of DC plasma, whereas the O content of PDC plasma is higher. The addition of water leads in an increase in the plume temperature and in the production of •OH with two types of power supplies. The production of O inversely shows a declining tendency with higher water ratio. The most important finding is that the PDC plasma with 100% water ratio achieves lower temperature and more abundant production of •OH and O, compared with DC plasma with 0% water ratio.

  16. An Improved DC Recovery Method from AC Coefficients of DCT-Transformed Images

    CERN Document Server

    Li, Shujun; Saupe, Dietmar; Kuo, C -C Jay

    2010-01-01

    Motivated by the work of Uehara et al. [1], an improved method to recover DC coefficients from AC coefficients of DCT-transformed images is investigated in this work, which finds applications in cryptanalysis of selective multimedia encryption. The proposed under/over-flow rate minimization (FRM) method employs an optimization process to get a statistically more accurate estimation of unknown DC coefficients, thus achieving a better recovery performance. It was shown by experimental results based on 200 test images that the proposed DC recovery method significantly improves the quality of most recovered images in terms of the PSNR values and several state-of-the-art objective image quality assessment (IQA) metrics such as SSIM and MS-SSIM.

  17. A New Sliding Mode Controller for DC/DC Converters in Photovoltaic Systems

    Directory of Open Access Journals (Sweden)

    M. Sarvi

    2013-01-01

    Full Text Available DC/DC converters are widely used in many industrial and electrical systems. As DC/DC converters are nonlinear and time-variant systems, the application of linear control techniques for the control of these converters is not suitable. In this paper, a new sliding mode controller is proposed as the indirect control method and compared to a simple direct control method in order to control a buck converter in photovoltaic applications. The solar arrays are dependent power sources with nonlinear voltage-current characteristics under different environmental conditions (insolation and temperature. From this point of view, the DC/DC converter is particularly suitable for the application of the sliding mode control in photovoltaic application, because of its controllable states. Simulations are performed in Matlab/Simulink software. The simulation results are presented for a step change in reference voltage and input voltage as well as step load variations. The simulations results of proposed method are compared with the conventional PID controller. The results show the good performance of the proposed sliding mode controller. The proposed method can be used for the other DC/DC converter.

  18. Synthesis of a CNT-grafted TiO(2) nanocatalyst and its activity triggered by a DC voltage.

    Science.gov (United States)

    Kuo, Chien-Sheng; Tseng, Yao-Hsuan; Lin, Hong-Ying; Huang, Chia-Hung; Shen, Chih-Yen; Li, Yuan-Yao; Ismat Shah, S; Huang, Chin-Pao

    2007-11-21

    Carbon nanotube (CNT)-grafted TiO(2) (CNT/TiO(2)) was synthesized as an electrically conductive catalyst that exhibits redox ability under electrical excitation besides ultraviolet (UV) irradiation. The CNT/TiO(2) material was synthesized by a two-step process. Ni nanoparticles were photodeposited onto TiO(2) first. The Ni nanoparticles then served as seeds for the growth of CNTs using the chemical vapor deposition (CVD) of C(2)H(2). The CNT/TiO(2) nanocomposite exhibits strong oxidation activity toward NO gas molecules via both photocatalysis under UV irradiation and electrocatalysis under a DC voltage of 500 V in dark conditions.

  19. Optimal Control for DC Side Voltage of Active Power Filter Based on Auto-Disturbance Rejection Control%基于自抗扰控制技术的有源电力滤波器直流侧电压优化控制

    Institute of Scientific and Technical Information of China (English)

    丁祖军; 刘保连; 张宇林

    2013-01-01

      直流侧电压的稳定控制是保证有源电力滤波器(active power filter,APF)正常工作的关键环节之一。对APF直流侧电压进行建模,在dq坐标系中分析了直流侧电压与d轴电流的数学关系,进而提出了 APF 直流侧电压自抗扰控制器的整体设计方法,给出了自抗扰控制器中的跟踪微分单元、扩张状态观测器和误差反馈单元的设计方法,并采用线性方法对该控制器进行优化,提高了响应速度与控制精度。仿真与试验结果验证了该设计方法的可行性。%  The stable control of DC side voltage is one of key links to ensure normal operation of active power filter (APF). The model of DC side voltage of APF is established and the mathematical relation between DC side voltage and d-axis current is analyzed in dq coordinate system, and then a total design method for auto disturbances rejection controller (ADRC) of DC side voltage of APF is proposed. The design method of tracking differentiator (TD), extended state observer (ECO) and error feedback unit of ADRC are given, and linear optimization is applied to the ADRC to improve its response speed and control accuracy. The feasibility of the proposed design method is validated by simulation and experimental results.

  20. 一种光伏用高升压比高效率直流变换器%A High Voltage Gain High Efficiency DC/DC Converter for PV System

    Institute of Scientific and Technical Information of China (English)

    卓生荣; 皇甫宜耿

    2016-01-01

    以光伏为代表的新能源发电日益受到重视。为提高光伏发电系统的可靠性与发电效率,两级式光伏并网发电系统的前级DC/DC变换器对升压比和效率提出了要求。首先对FIBC 拓扑的工作原理、高升压性能、低电力电子器件应力等进行详细分析,与传统Boost 电路的对比结果验证了 FIBC 的优越性;然后建立了 Boost和FIBC电路的损耗模型,给出了额定工况下的损耗分布和效率,结果表明同电路参数下FIBC 具有更高的效率;接着利用交错控制技术,对FIBC 电感参数进行了优化,进一步提高变换器效率;最后给出Boost 与FIBC 和优化FIBC 在不同工作电流下的效率曲线,结果表明优化后FIBC 效率提高明显,比Boost 更适合用于低压大功率光伏发电系统中。基于Matlab/Simulink平台的仿真结果表明,使用交错技术可以优化电感参数,直流母线输出电压能够稳定在400 V。%The new energy power generation system, like the PV system, is getting more and more attention. In order to improve the reliability and efficiency of the two-level PV generation system, the high voltage gain and high efficiency of the front end is expected. The comparison result between the Floating-output Interleaved-input Boost-derived Converter(FIBC)and the Boost in voltage gain and power electronics device stress validates the superiority of the former. Then the loss models of both circuits have been presented, as well as the power distribution under the rated working condition, which shows that the FIBC is more efficient. Based on the interleaved technology, the parameter of the inductance is optimized and hence reduces the DC resistance and improves the efficiency. Finally, the efficiency versus current curve of the Boost, FIBC and the optimized FIBC is given, which shows that the FIBC is more suitable for low voltage high power PV generation system for its higher efficiency under large current

  1. SoC-Based Droop Method for Distributed Energy Storage in DC Microgrid Applications

    DEFF Research Database (Denmark)

    Lu, Xiaonan; Sun, Kai; Guerrero, Josep M.

    2012-01-01

    With the progress of distributed generation nowadays, microgrid is employed to integrate different renewable energy sources into a certain area. For several kinds of renewable sources have DC outputs, DC microgrid has drawn more attention recently. Meanwhile, to deal with the uncertainty...... in the output of microgrid system, distributed energy storage is usually adopted. Considering that the state-of-charge (SoC) of each battery may not be the same, decentralized droop control method based on SoC is shown in this paper to reach proportional load power sharing. With this method, the battery...

  2. Voltage-Balancing Method for Modular Multilevel Converters Switched at Grid Frequency

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2015-01-01

    The modular multilevel converter (MMC) becomes attractive for high-voltage and high-power applications due to its high modularity, availability, and power quality. The voltage balance issue of capacitors is very important in the MMC, and the balancing of the capacitor voltage is increasingly...... difficult as the switching frequency is reduced. In this paper, a voltage-balancing method is proposed for the MMC switched at grid frequency with reduced losses and does not rely on the arm current. By assigning the low-frequency pulses with different pulse widths, the capacitor charge transfer in the MMC...... can be controlled for keeping the capacitor voltage balancing in the MMC. Simulations and experimental studies of the MMC are conducted, and the results confirm the effectiveness of the proposed capacitor voltage-balancing method....

  3. Distributed Secondary Control for DC Microgrid Applications with Enhanced Current Sharing Accuracy

    DEFF Research Database (Denmark)

    Lu, Xiaonan; Guerrero, Josep M.; Sun, Kai

    2013-01-01

    are used locally as the distributed secondary controllers in each converter to enhance the current sharing accuracy and restore the dc bus voltage simultaneously. All the controllers are realized locally and the LBC system is only used for changing the data of dc voltage and current. Thus, a decentralized......, a distributed secondary control method is proposed. Droop control is employed as the primary control method for load current sharing. Meanwhile, the dc output voltage and current in each module is transferred to the others by the low bandwidth communication (LBC) network. Average voltage and current controllers...

  4. Method to reduce arc blow during DC arc welding of pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Espina-Hernandez, J. H.; Rueda-Morales, G.L.; Caleyo, F.; Hallen, J. M. [Instituto Politecnico Nacional, Mexico, (Mexico); Lopez-Montenegro, A.; Perz-Baruch, E. [Pemex Exploracion y Produccion, Tabasco, (Mexico)

    2010-07-01

    Steel pipelines are huge ferromagnetic structures and can be easily subjected to arc blow during the DC arc welding process. The development of methods to avoid arc blow during pipeline DC arc welding is a major objective in the pipeline industry. This study developed a simple procedure to compensate the residual magnetic field in the groove during DC arc welding. A Gaussmeter was used to perform magnetic flux density measurements in pipelines in southern Mexico. These data were used to perform magnetic finite element simulations using FEMM. Different variables were studied such as the residual magnetic field in the groove or the position of the coil with respect to the groove. An empirical predictive equation was developed from these trials to compensate for the residual magnetic field. A new method of compensating for the residual magnetic field in the groove by selecting the number of coil turns and the position of the coil with respect to the groove was established.

  5. Systems and methods for process and user driven dynamic voltage and frequency scaling

    Science.gov (United States)

    Mallik, Arindam; Lin, Bin; Memik, Gokhan; Dinda, Peter; Dick, Robert

    2011-03-22

    Certain embodiments of the present invention provide a method for power management including determining at least one of an operating frequency and an operating voltage for a processor and configuring the processor based on the determined at least one of the operating frequency and the operating voltage. The operating frequency is determined based at least in part on direct user input. The operating voltage is determined based at least in part on an individual profile for processor.

  6. Flashover Characteristics of Flat Plate Model Under DC Voltage in Wind-sand Condition%风沙条件下的平板模型直流沿面放电特性

    Institute of Scientific and Technical Information of China (English)

    司马文霞; 马高权; 杨庆

    2008-01-01

    The influence of sand dust on discharge of external insulation has caused widespread concern. At present, the research results show wind-sand electricity has a remarkable effect on the discharge characteristics of insulator and has little influence on the discharge characteristics of air gap. The flashover of insulator strings occurs along the insulator surface and air gaps, and the sand dust deposited on the insulator surface may affect the flashover characteristics of insulator strings. This paper studies the flashover characteristics of flat plate model under DC voltage in wind-sand condition. The experimental results show that under positive polarity voltage, the flashover voltage of the flat plate model has a maximum value, while under negative polarity voltage, the flashover voltage of the flat plate model has a minimum value with a certain degree of sand dust deposition. The wind or sand in sand-dust weather has an important effect on the flashover characteristics of the flat plate model. In certain variation range of electric charge, electric charge of sand dust has little effect on the flashover voltage of flat plate model under DC voltage. The deposition of sand has significant influence on the flashover process of flat plate model, which is related to the deposition density and moisture content of sand particle.

  7. DC/DC converter with improved rectification for higher efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Maisel, Peter; Saliternig, Martin [Continental AG, Nuernberg (Germany)

    2010-07-01

    High-power dc-dc converters are an important element of the electrical system of electric vehicles and hybrid electric vehicles. These complex modular components provide the link between the high-voltage level used for the powertrain and the low-voltage bus for the lighting system, engine management and auxiliary needs in the vehicle. The essential requirements for all converters are high efficiency, compact size, lightweight and reliability. A very popular method to increase the efficiency is the synchronous rectification. Parasitic inductances in the commutation circuit and reverse recovery effects can produce a ringing with voltage overshoots at the diodes and the transistors. These spikes can cause higher average power dissipation in the seminconductors and higher EMI (electromagnetic interference).

  8. Production of carbon nanotubes by the magnetron DC sputtering method

    NARCIS (Netherlands)

    Antonenko, SV; Mal'tsev, SN

    2005-01-01

    Carbon films containing multiwall nanotubes were produced by the magnetron de sputtering method. A graphite disc with Y and Ni catalyst plates was used as a target. The structural and morphological properties of the films were investigated using a JEM 2000EXII transmission electron microscope. The f

  9. General Consideration of Measuring System for Operational Test of Thyristor Valves of Ultra High Voltage DC Power Transmission

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hui-gao; XU Fan; ZHANG Chang-chun; HU Zhi-long; LIU Pu; HUANG Xi-dong; WAN Gan; DING Qian

    2011-01-01

    Thyristor valve is one of the key equipments for ultra high voltage direct current (UHVDC)power transmission projects.Before being installed on site,they need to be tested in a laboratory in order to verify their operational performance to satisfy the technical specification of project related.Test facilities for operational tests of thyristor valves are supposed to enable to undertake more severe electrical stresses than those being applied in the thyristor valves under test (test objects).On the other hand,the stresses applied into the test objects are neither higher nor lower than specified by the specification,because inappropriate stresses applied would result in incorrect evaluation of performance on the test objects,more seriously,would cuase the damage of test objects with expensive cost losing.Generally,the process of operational tests is complicated and performed in a complex synthetic test circuit(hereafter as STC),where there are a lot of sensors used for measuring,monitoring and protection on line to ensure that the test circuit functions in good condition.Therefore,the measuring systems embedded play a core role in STC,acting like "eyes".Based on the first project of building up a STC in China,experience of planning measuring systems is summarized so as to be referenced by related engineers.

  10. Direct-detect Type Residual Charge Method with Short-term Voltage Up-down for Water Tree Deterioration Diagnosis in XLPE Cable

    Science.gov (United States)

    Ootaka, Iwao; Aoki, Masaru; Togashi, Hirotaka; Tsujimoto, Tomiyuki; Nakade, Masahiko

    Water tree is one of the unique type of deterioration in XLPE cable, which is the primary cause of aging breakdown. Water tree, which bridges between conductor and shield, can be detected easily, such as DC leakage current method. However, 22kV class or above XLPE cable, most of breakdown occurs before water tree bridges, and there used to be no effective method for detecting non-bridged water tree. In this paper, we've found residual charge in harmful water tree relaxes quickly with AC voltage application. To detect this type of residual charge, we've developed new diagnosis method with “direct-detect type residual charge method" and “short-term voltage up-down method". This new method found to be very effective for diagnosing over 22kV class XLPE cable lines.

  11. Adaptable DC offset correction

    Science.gov (United States)

    Golusky, John M. (Inventor); Muldoon, Kelly P. (Inventor)

    2009-01-01

    Methods and systems for adaptable DC offset correction are provided. An exemplary adaptable DC offset correction system evaluates an incoming baseband signal to determine an appropriate DC offset removal scheme; removes a DC offset from the incoming baseband signal based on the appropriate DC offset scheme in response to the evaluated incoming baseband signal; and outputs a reduced DC baseband signal in response to the DC offset removed from the incoming baseband signal.

  12. A NOVEL METHOD OF VOLTAGE SAG AND SWELL ESTIMATION FOR POWER SYSTEM APPLICATIONS

    Directory of Open Access Journals (Sweden)

    A. Vetrivel

    2013-01-01

    Full Text Available This study presents four simple mathematical models to build the voltage shape with the knowledge of few parameters and detects voltage sag and swells accurately. Fourier series, cubic polynomial, Rational functions and Sum of Sin functions are used in this study to model the voltage profile. A new algorithm is developed to detect sag or swell in all the four models. The voltage estimation due to cubic polynomial has more voltage error and then rational function. The sum of sine function and Fourier series functions does accurate voltage estimation. Errors due to various functions are also tabulated for one electrical cycle. The performance of each method has been compared with other to know the effectiveness of different models and their results are presented.

  13. Pulsed voltage electrospray ion source and method for preventing analyte electrolysis

    Science.gov (United States)

    Kertesz, Vilmos; Van Berkel, Gary

    2011-12-27

    An electrospray ion source and method of operation includes the application of pulsed voltage to prevent electrolysis of analytes with a low electrochemical potential. The electrospray ion source can include an emitter, a counter electrode, and a power supply. The emitter can include a liquid conduit, a primary working electrode having a liquid contacting surface, and a spray tip, where the liquid conduit and the working electrode are in liquid communication. The counter electrode can be proximate to, but separated from, the spray tip. The power system can supply voltage to the working electrode in the form of a pulse wave, where the pulse wave oscillates between at least an energized voltage and a relaxation voltage. The relaxation duration of the relaxation voltage can range from 1 millisecond to 35 milliseconds. The pulse duration of the energized voltage can be less than 1 millisecond and the frequency of the pulse wave can range from 30 to 800 Hz.

  14. A NOVEL OVER—VOLTAGE PROTECTION METHOD FOR 600V SPIC

    Institute of Scientific and Technical Information of China (English)

    LanLei; YeXingning

    2002-01-01

    A novel over-voltage protection method for 600V BPIC(Smart Power IC) is proposed in this paper.The combining FFLRs(Floating Field Limiting Rings) system is designed to be a voltage detector.The detector's voltage can turn off the switch of the APFC(Active Power Factor Correction )Circuit and the bus voltage would fall from 600VDC to 300VDC,so the SPIC and power devices can be protected.The advantages of this design are that the total protection circuits are integrated in SPIC and technologically compatible with CMOS or BCD(Bipolar CMOS-DMOS) technology.

  15. A NOVEL OVER-VOLTAGE PROTECTION METHOD FOR 600V SPIC

    Institute of Scientific and Technical Information of China (English)

    Han Lei; Ye Xingning

    2002-01-01

    A novel over-voltage protection method for 600V SPIC (Smart Power IC) is proposed in this paper. The combining FFLRs (Floating Field Limiting Rings) system is designed to be a voltage detector. The detector's voltage can turn off the switch of the APFC (Active Power Factor Correction) circuit and the bus voltage would fall from 600VDC to 300VDC, so the SPIC and power devices can be protected. The advantages of this design are that the total protection circuits are integrated in SPIC and technologically compatible with CMOS or BCD(BipolarCMOS-DMOS) technology.

  16. A novel method for simulation of brushless DC motor servo-control system based on MATLAB

    Science.gov (United States)

    Tao, Keyan; Yan, Yingmin

    2006-11-01

    This paper provides a research about the simulation of brush-less DC motor (BLDCM) servo control system. Based on the mathematical model of Brush-less DC motor (BLDCM), built the system simulation model with the MATLAB software. When the system model is made, the isolated functional blocks, such as BLDCM block, the rotor's position detection block, change-phase logic block etc. have been modeled. By the organic combination of these blocks, the model of BLDCM can be established easily. The reasonability and validity have been testified by the simulation results and this novel method offers a new thought way for designing and debugging actual motors.

  17. Method and device for ion mobility separations

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, Yehia M.; Garimella, Sandilya V. B.; Smith, Richard D.

    2017-07-11

    Methods and devices for ion separations or manipulations in gas phase are disclosed. The device includes a single non-planar surface. Arrays of electrodes are coupled to the surface. A combination of RF and DC voltages are applied to the arrays of electrodes to create confining and driving fields that move ions through the device. The DC voltages are static DC voltages or time-dependent DC potentials or waveforms.

  18. AC/DC Power Flow Computation Based on Improved Levenberg-Marquardt Method

    Science.gov (United States)

    Cao, Jia; Yan, Zheng; Fan, Xiang; Xu, Xiaoyuan; Li, Jianhua; Cao, Lu

    2015-02-01

    Under the case of ill-conditioning system, this paper is concerned with the AC/DC power flow calculation. The improved Levenberg-Marquardt (ILM) method with adaptive damping factor selection is applied to solve the AC/DC power flow problem. The main purpose of this paper is as follows: one is to provide comparison reference between Newton method, classical LM method (CLM) and ILM method under the well-conditioning system; the other is to research what is the maximal load withstood by power system, under the case of ill-conditioning. Finally, those methods are tested on the 22-bus, the IEEE 118-bus AC/DC system, respectively. Numerical results indicate that the ILM method has the advantage of fast convergent speed. When expanding loads in a certain extent, ILM method can at least find least square solutions, whereas Newton method and CLM method would divergent, and the convergent property of Newton method can be improved by taking some measurements using the information of a least square solution obtained by ILM method.

  19. Minimum-Voltage Vector Injection Method for Sensorless Control of PMSM for Low-Speed Operations

    DEFF Research Database (Denmark)

    Xie, Ge; Lu, Kaiyuan; Kumar, Dwivedi Sanjeet

    2016-01-01

    In this paper, a simple signal injection method is proposed for sensorless control of PMSM at low speed, which ideally requires one voltage vector only for position estimation. The proposed method is easy to implement resulting in low computation burden. No filters are needed for extracting...... may also be further developed to inject two opposite voltage vectors to reduce the effects of inverter voltage error on the position estimation accuracy. The effectiveness of the proposed method is demonstrated by comparing with other sensorless control method. Theoretical analysis and experimental...

  20. A Hybrid Optimization Method for Reactive Power and Voltage Control Considering Power Loss Minimization

    DEFF Research Database (Denmark)

    Liu, Chengxi; Qin, Nan; Bak, Claus Leth;

    2015-01-01

    This paper proposes a hybrid optimization method to optimally control the voltage and reactive power with minimum power loss in transmission grid. This approach is used for the Danish automatic voltage control (AVC) system which is typically a non-linear non-convex problem mixed with both continu...

  1. Methods, systems and apparatus for adjusting modulation index to improve linearity of phase voltage commands

    Energy Technology Data Exchange (ETDEWEB)

    Gallegos-Lopez, Gabriel; Perisic, Milun; Kinoshita, Michael H.

    2017-03-14

    Embodiments of the present invention relate to methods, systems and apparatus for controlling operation of a multi-phase machine in a motor drive system. The disclosed embodiments provide a mechanism for adjusting modulation index of voltage commands to improve linearity of the voltage commands.

  2. Control of improved full-bridge three-level DC/DC converter for wind turbines in a DC grid

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2013-01-01

    transformer in the IFBTL dc/dc converter. A modulation strategy, including two operation modes, is proposed for the IFBTL dc/dc converter. Then, a voltage balancing control strategy is proposed for the IFBTL dc/dc converter. Furthermore, the control of the wind turbine based on the IFBTL dc/dc converter......This paper presents an improved full-bridge three-level (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency...... in a dc-grid system is presented. Finally, a small-scale IFBTL dc/dc converter prototype was built and tested in the laboratory, and the results verify the theoretical analysis....

  3. Method and system for a gas tube-based current source high voltage direct current transmission system

    Energy Technology Data Exchange (ETDEWEB)

    She, Xu; Chokhawala, Rahul Shantilal; Bray, James William; Sommerer, Timothy John; Zhou, Rui; Zhang, Di

    2017-08-29

    A high-voltage direct-current (HVDC) transmission system includes an alternating current (AC) electrical source and a power converter channel that includes an AC-DC converter electrically coupled to the electrical source and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and the DC-AC inverter each include a plurality of legs that includes at least one switching device. The power converter channel further includes a commutating circuit communicatively coupled to one or more switching devices. The commutating circuit is configured to "switch on" one of the switching devices during a first portion of a cycle of the H-bridge switching circuits and "switch off" the switching device during a second portion of the cycle of the first and second H-bridge switching circuits.

  4. Simulation of Outer Rotor Permanent Magnet Brushless DC Motor Using Finite Element Method for Torque Improvement

    OpenAIRE

    Uma Devi Kumaravelu; Sanavullah Mohamed Yakub

    2012-01-01

    A method of simulation and modeling outer rotor permanent magnet brushless DC (ORPMBLDC) motor under dynamic conditions using finite element method by FEMM 4.2 software package is presented. In the proposed simulation, the torque developed at various positions of the rotor, under a complete cycle of excitation of the stator, is analysed. A novel method of sinusoidal excitation is proposed to enhance the overall torque development of ORPMBLDC motor.

  5. Simulation of Outer Rotor Permanent Magnet Brushless DC Motor Using Finite Element Method for Torque Improvement

    Directory of Open Access Journals (Sweden)

    Uma Devi Kumaravelu

    2012-01-01

    Full Text Available A method of simulation and modeling outer rotor permanent magnet brushless DC (ORPMBLDC motor under dynamic conditions using finite element method by FEMM 4.2 software package is presented. In the proposed simulation, the torque developed at various positions of the rotor, under a complete cycle of excitation of the stator, is analysed. A novel method of sinusoidal excitation is proposed to enhance the overall torque development of ORPMBLDC motor.

  6. High-mobility ZrInO thin-film transistor prepared by an all-DC-sputtering method at room temperature.

    Science.gov (United States)

    Xiao, Peng; Dong, Ting; Lan, Linfeng; Lin, Zhenguo; Song, Wei; Luo, Dongxiang; Xu, Miao; Peng, Junbiao

    2016-04-27

    Thin-film transistors (TFTs) with zirconium-doped indium oxide (ZrInO) semiconductor were successfully fabricated by an all-DC-sputtering method at room temperature. The ZrInO TFT without any intentionally annealing steps exhibited a high saturation mobility of 25.1 cm(2)V(-1)s(-1). The threshold voltage shift was only 0.35 V for the ZrInO TFT under positive gate bias stress for 1 hour. Detailed studies showed that the room-temperature ZrInO thin film was in the amorphous state with low carrier density because of the strong bonding strength of Zr-O. The room-temperature process is attractive for its compatibility with almost all kinds of the flexible substrates, and the DC sputtering process is good for the production efficiency improvement and the fabrication cost reduction.

  7. Measurement and analysis of postsynaptic potentials using a novel voltage-deconvolution method.

    Science.gov (United States)

    Richardson, Magnus J E; Silberberg, Gilad

    2008-02-01

    Accurate measurement of postsynaptic potential amplitudes is a central requirement for the quantification of synaptic strength, dynamics of short-term and long-term plasticity, and vesicle-release statistics. However, the intracellular voltage is a filtered version of the underlying synaptic signal and so a method of accounting for the distortion caused by overlapping postsynaptic potentials must be used. Here a voltage-deconvolution technique is demonstrated that defilters the entire voltage trace to reveal an underlying signal of well-separated synaptic events. These isolated events can be cropped out and reconvolved to yield a set of isolated postsynaptic potentials from which voltage amplitudes may be measured directly-greatly simplifying this common task. The method also has the significant advantage of providing a higher temporal resolution of the dynamics of the underlying synaptic signal. The versatility of the method is demonstrated by a variety of experimental examples, including excitatory and inhibitory connections to neurons with passive membranes and those with activated voltage-gated currents. The deconvolved current-clamp voltage has many features in common with voltage-clamp current measurements. These similarities are analyzed using cable theory and a multicompartment cell reconstruction, as well as direct comparison to voltage-clamp experiments.

  8. INVESTIGATION OF TRACKING OF VOLTAGE SIGNAL CONTAINING HARMONICS AND SPIKE BY USING RECURSIVE LEAST SQUARES METHOD

    Directory of Open Access Journals (Sweden)

    H. Hüseyin SAYAN

    2009-01-01

    Full Text Available In this study, recursive least squares method (RLSM that is one of the adaptable classical methods was used. Firstly forgetting factor was adapted to RLSM. Phase information of voltage signal belonging to an electric power network that contains harmonics and spike was obtained by developed approach. Then responses of the algorithm were investigated for voltage collapse, phase shift and spike. Simulation was implemented by using MATLAB® code. Results of simulation were examined and efficiency of method was presented.

  9. An Identification Method of Magnetizing Inrush Current Phenomena by Voltage Waveform

    Science.gov (United States)

    Naitoh, Tadashi; Takeda, Keiki; Toyama, Atsushi; Maeda, Tatsuhiko

    In this paper, the authors propose a new identification method of the magnetizing inrush current phenomena. In general, the identification is done using with current waveform. However, the saturation of current transformer can't give waveform. Therefore, the authors introduce the identification method using with voltage waveform, in which the saturation of voltage transformer doesn't happen. And then, applying the Aitken's Δ2-process, it is showed that the new identification method gives the exact saturation on/off time.

  10. Comparison of Performance and Realization Effort of a Very Sparse Matrix Converter to a Voltage DC Link PWM Inverter with Active Front End

    Science.gov (United States)

    Round, Simon; Schafmeister, Frank; Heldwein, Marcelo; Pereira, Eduardo; Serpa, Leonardo; Kolar, Johann

    This paper undertakes a comparison of the very sparse matrix converter (VSMC) and the back-to-back voltage DC-link converter (BBC) for a permanent magnetic synchronous motor drive application. The VSMC has the same functionality as the conventional matrix converter but a reduced number of switches and lower control complexity. The two converters are designed, using the same IGBT power modules, with a switching frequency of 40kHz and a thermal rating of 6.8kW at an ambient temperature of 45°C. From the design, the volume of the VSMC is 2.3 liters and is half that of the BBC. The efficiency for the VSMC at full load is 94.5% compared to 92% for the BBC. At very low output frequencies the output current of the VSMC can be increased by 25% above nominal compared to a 54% decrease for the BBC. Overall the VSMC offers advantages in volume and efficiency for motor drive applications requiring switching frequencies above 10kHz.

  11. Forward modeling of marine DC resistivity method for a layered anisotropic earth

    Science.gov (United States)

    Yin, Chang-Chun; Zhang, Ping; Cai, Jing

    2016-06-01

    Since the ocean bottom is a sedimentary environment wherein stratification is well developed, the use of an anisotropic model is best for studying its geology. Beginning with Maxwell's equations for an anisotropic model, we introduce scalar potentials based on the divergence-free characteristic of the electric and magnetic (EM) fields. We then continue the EM fields down into the deep earth and upward into the seawater and couple them at the ocean bottom to the transmitting source. By studying both the DC apparent resistivity curves and their polar plots, we can resolve the anisotropy of the ocean bottom. Forward modeling of a high-resistivity thin layer in an anisotropic half-space demonstrates that the marine DC resistivity method in shallow water is very sensitive to the resistive reservoir but is not influenced by airwaves. As such, it is very suitable for oil and gas exploration in shallowwater areas but, to date, most modeling algorithms for studying marine DC resistivity are based on isotropic models. In this paper, we investigate one-dimensional anisotropic forward modeling for marine DC resistivity method, prove the algorithm to have high accuracy, and thus provide a theoretical basis for 2D and 3D forward modeling.

  12. A Novel Dual-input Isolated Current-Fed DC-DC Converter for Renewable Energy System

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

    2010-01-01

    In this paper, a novel isolated current-fed DC-DC converter (boost-type) with two input power sources based on multi-transformer structure, which is suitable for fuel cells and super-capacitors hybrid energy system, is proposed and designed. With particular transformer windings connection strategy......, the proposed converter can draw power from two different DC sources with lower voltage and deliver it to the higher voltage DC bus or load individually and simultaneously. The detailed operation principle of the proposed converter has been analyzed in dual-input mode and single-input mode, respectively....... Furthermore, the method to increase the number of input ports, the magnetic integration structure, and ground loop decoupling are discussed. Experimental results from the lab prototype converter with two DC voltage sources verify the validity of the theoretical analysis and design of the converter....

  13. Methods, systems and apparatus for controlling third harmonic voltage when operating a multi-space machine in an overmodulation region

    Energy Technology Data Exchange (ETDEWEB)

    Perisic, Milun; Kinoshita, Michael H; Ranson, Ray M; Gallegos-Lopez, Gabriel

    2014-06-03

    Methods, system and apparatus are provided for controlling third harmonic voltages when operating a multi-phase machine in an overmodulation region. The multi-phase machine can be, for example, a five-phase machine in a vector controlled motor drive system that includes a five-phase PWM controlled inverter module that drives the five-phase machine. Techniques for overmodulating a reference voltage vector are provided. For example, when the reference voltage vector is determined to be within the overmodulation region, an angle of the reference voltage vector can be modified to generate a reference voltage overmodulation control angle, and a magnitude of the reference voltage vector can be modified, based on the reference voltage overmodulation control angle, to generate a modified magnitude of the reference voltage vector. By modifying the reference voltage vector, voltage command signals that control a five-phase inverter module can be optimized to increase output voltages generated by the five-phase inverter module.

  14. METHODICAL TUNING OF PROPORTIONAL PLUS INTEGRAL CONTROLLERS FOR CASCADE CONTROL OF SEPARATELY EXCITED DC MOTORS

    Directory of Open Access Journals (Sweden)

    Ibrahim Al-Abbas

    2012-01-01

    Full Text Available The cascade control of DC motors by PI controllers was extensively used in industry. Approximation rules based on plotting the output of the system or on computer simulation were used to determine the parameters of these controllers. This study was done to develop mathematical expressions to calculate the parameters of these controllers. Output time functions of the system and there derivatives were used to obtain mathematical relationships relating directly the motor parameters and the controller parameters. These relationships were used in tuning process of the cascade system. The dynamic performances of the system were examined in single loop form and in closed loop form for a step change in control variable (the input voltage as well as for step change in disturbance (mechanical load. The performances of current closed loop system and the speed closed loop were acceptable. The steady state error was zero and the maximum overshoot was less than 20%. The developed relationships can be used in design and analysis of cascade DC drive systems and cascade AC drive systems.

  15. Nonlinear Phenomena and Resonant Parametric Perturbation Control in QR-ZCS Buck DC-DC Converters

    Science.gov (United States)

    Hsieh, Fei-Hu; Liu, Feng-Shao; Hsieh, Hui-Chang

    The purpose of this study is to investigate the chaotic phenomena and to control in current-mode controlled quasi-resonant zero-current-switching (QR-ZCS) DC-DC buck converters, and to present control of chaos by resonant parametric perturbation control methods. First of all, MATLAB/SIMULINK is used to derive a mathematical model for QR-ZCS DC-DC buck converters, and to simulate the converters to observe the waveform of output voltages, inductance currents and phase-plane portraits from the period-doubling bifurcation to chaos by changing the load resistances. Secondly, using resonant parametric perturbation control in QR-ZCS buck DC-DC converters, the simulation results of the chaotic converter form chaos state turn into stable state period 1, and improve ripple amplitudes of converters under the chaos, to verify the validity of the proposes method.

  16. Research on Voltage Sag Protection Based on DC Power Supply Technology%基于直流供电技术的电压暂降保护系统研究

    Institute of Scientific and Technical Information of China (English)

    李江龙; 王丽; 陈文波

    2015-01-01

    The inverter is widely used for its obvious advantages in soft start, variable frequency speed control, optimal design, economic operation and so on. During voltage sag, the inverter will be tripped because of low voltage protection, which would cause the important motor driven by inverter to stop working. This will result in non planned outage in the continuous production enterprises, leading to huge economic losses and even personal safety accidents and environment problems. According to the characteristics of inverter’s AC-DC-AC structure and combining power electronics technology two kinds of voltage sag protection (VSP) systems are researched and developed based on DC power supply technology which take network residual voltage and batteries as energy source respectively. And through Boost DC/DC converter, the VSP system outputs a constant DC voltage, supporting inverter’s DC bus. Experimental data and field applications show that the two kinds of VSP system can ensure the normal operation of inverter during voltage sag which greatly improves the reliability on demand side and saves a lot of economic loss for users.%变频器在软启动、变频调速、优化设计、经济运行等方面具有明显优势,得到广泛应用。在电压暂降期间,变频器会因低压保护而跳闸,造成连续性生产企业非计划停运,带来巨大的经济损失和事故。根据变频器交-直-交的特性,结合电力电子技术,研究开发了两种基于直流供电技术的电压暂降保护系统。两种保护系统分别利用电网残压和蓄电池组作为能量来源,通过Boost DC/DC变换器,输出恒定的直流电压,为变频器直流母线提供恒定的直流电。实验数据和现场应用表明,该两种电压暂降保护系统可以确保变频器在电压暂降期间正常运行,大大提高了供电可靠性,为用户避免了大量的经济损失。

  17. Method of reliability tolerance design based on EDA technology and its application on DC hybrid contactor

    Institute of Scientific and Technical Information of China (English)

    WANG Shu-juan; SHA You-tao; ZHANG Hui; ZHAI Guo-fu

    2007-01-01

    Tolerance design, including tolerance analysis and distribution, is an important part of the electronic system's reliability design. The traditional design needs to construct mathematic model of material circuit, which involves large amount of workload and lacks of practicability. This paper discusses the basic theory of electronic system's reliability tolerance design and presents a new design method based on EDA (Electronic Design Automatic) software. This method has been validated through the application research on reliability tolerance design of the DC hybrid contactor's control circuit.

  18. Classification of methods for measuring current-voltage characteristics of semiconductor devices

    Directory of Open Access Journals (Sweden)

    Iermolenko Ia. O.

    2014-06-01

    Full Text Available It is shown that computer systems for measuring current-voltage characteristics are very important for semiconductor devices production. The main criteria of efficiency of such systems are defined. It is shown that efficiency of such systems significantly depends on the methods for measuring current-voltage characteristics of semiconductor devices. The aim of this work is to analyze existing methods for measuring current-voltage characteristics of semiconductor devices and to create the classification of these methods in order to specify the most effective solutions in terms of defined criteria. To achieve this aim, the most common classifications of methods for measuring current-voltage characteristics of semiconductor devices and their main disadvantages are considered. Automated and manual, continuous, pulse, mixed, isothermal and isodynamic methods for measuring current-voltage characteristics are analyzed. As a result of the analysis and generalization of existing methods the next classification criteria are defined: the level of automation, the form of measurement signals, the condition of semiconductor device during the measurements, and the use of mathematical processing of the measurement results. With the use of these criteria the classification scheme of methods for measuring current-voltage characteristics of semiconductor devices is composed and the most effective methods are specified.

  19. Startup Capability of Boost DC/DC Converter%Boost DC/DC的低压启动能力

    Institute of Scientific and Technical Information of China (English)

    向乾尹; 冯全源

    2011-01-01

    An analytical model was proposed to calculate the minimum startup voltage of a boost DC/ DC converter under a constant current load. The factors, such as the current load, the parasitic parameters, the saturation current and on-resistance of the power switch, the switching frequency, and the minimum startup voltage, etc. , which affect the startup capability of the boost DC/DC converter were analyzed with a steady-state analysis method. The model was applied to the design of a boost DC/ DC converter with a 0. 6 jxm CMOS process, and the maximum error of the minimum startup voltage calculated by the proposed model was 4. 5% compared with that by the HSPICE simulator.%为了准确预测Boost DC/DC低压启动能力,采用稳态分析方法,分析了电流负载、寄生参数、功率开关饱和电流及导通阻抗、开关频率、启动电路最低工作电压等因素对Boost DC/DC低压启动能力的影响,提出了预测Boost DC/DC恒流负载下最小启动电压的解析模型.将该模型应用于采用0.6 μm CMOS工艺的Boost DC/DC设计中,模型计算结果相对HSPICE仿真结果的最大误差为4.5%.本模型可推广至恒定电阻负载的情况.

  20. A New High Frequency Injection Method Based on Duty Cycle Shifting without Maximum Voltage Magnitude Loss

    DEFF Research Database (Denmark)

    Wang, Dong; Lu, Kaiyuan; Rasmussen, Peter Omand

    2015-01-01

    The conventional high frequency signal injection method is to superimpose a high frequency voltage signal to the commanded stator voltage before space vector modulation. Therefore, the magnitude of the voltage used for machine torque production is limited. In this paper, a new high frequency...... injection method, in which high frequency signal is generated by shifting the duty cycle between two neighboring switching periods, is proposed. This method allows injecting a high frequency signal at half of the switching frequency without the necessity to sacrifice the machine fundamental voltage...... amplitude. This may be utilized to develop new position estimation algorithm without involving the inductance in the medium to high speed range. As an application example, a developed inductance independent position estimation algorithm using the proposed high frequency injection method is applied to drive...

  1. Non-contact current and voltage sensing method using a clamshell housing and a ferrite cylinder

    Science.gov (United States)

    Carpenter, Gary D.; El-Essawy, Wael; Ferreira, Alexandre Peixoto; Keller, Thomas Walter; Rubio, Juan C.; Schappert, Michael

    2016-04-26

    A method of measurement using a detachable current and voltage sensor provides an isolated and convenient technique for to measuring current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing that contains the current and voltage sensors, which may be a ferrite cylinder with a hall effect sensor disposed in a gap along the circumference to measure current, or alternative a winding provided through the cylinder along its axis and a capacitive plate or wire disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.

  2. A New Approach for High Efficiency Buck-Boost DC/DC Converters Using Series Compensation

    Science.gov (United States)

    Itoh, Jun-Ichi; Fujii, Takashi

    This paper proposes a novel concept for non-isolated buck-boost DC/DC converter and control method. The proposed concept uses a series connection converter that only regulates the differential voltage between the input and output voltage. As a result, the power converter capacity is decreased. Moreover, the proposed circuit has advantages such as improved efficiency and losses reduction. The fundamental operation, control method, and design method of the proposed circuit are described in this paper. In addition, the validity of the proposed circuit is confirmed by carrying out simulations and experiments.

  3. Advanced High Power DC-DC Converter using A Novel Type Voltage Source Full-Bridge Soft-Switching PWM Inverter with High Frequency Transformer Link for Arc Welding Applications

    Science.gov (United States)

    Morimoto, Keiki; Doi, Toshimitsu; Manabe, Haruhiko; Ahmed, Tarek; Hiraki, Eiji; Lee, Hyun-Woo; Nakaoka, Mutsuo

    This paper presents a new circuit topology of full-bridge soft-switching PWM inverter linked DC-DC power converter composed of conventional full-bridge high frequency PWM inverter with high frequency transformer and an active quasi-resonant snubber consisting of an additional power switching device in series with DC busline and a lossless capacitor in parallel with DC busline. Under this proposed high frequency soft-switching PWM inverter linked DC-DC converter, four power switches in the full-bridge arms and DC busline series switch can achieve ZVS at turn-off commutation. By developing the advanced soft-switching PWM high frequency inverter type DC-DC converter, although the conduction power loss of DC busline series power switch increases a little, the total turn-off switching loss of full-bridge high frequency inverter power modules can be sufficiently lowered more and more in the higher frequency range of 60kHz. As a result, when the switching frequency of high frequency inverter power stage using IGBT power modules is designed so as to be more than about 10kHz, the more the switching frequency of inverter increases, the more this high frequency soft-switching DC-DC converter has remarkable advantage as for the power conversion efficiency as compared with the conventional hard-switching PWM inverter DC-DC converter. Its practical effectiveness of high power density and high performance is actually proved for TIG arc welding equipment in industry.

  4. An ANN Based Capicitor Voltage Balancing Method For Neutral Point Clamped Multi-Level Inverter

    Directory of Open Access Journals (Sweden)

    P.J.S. Praveen,

    2015-11-01

    Full Text Available Multi-level inverters are became popular for usage in medium voltage, low voltage power applications due to flexibility in control and better performance characteristics in terms of harmonic regulation. Neutral point clamped are popular as they require less number of sources as their input when compared with their counter parts i.e. cascaded multi-level inverters and found to be reliable when compared with flying capacitor based multi-level inverters. But when neutral clamped technologies are used for generation of three-phase voltages, the capacitors that are connected at input side experiences imbalance in their voltages, this makes neutral point clamped multi-level inverters less reliable. In the proposed work an attempt is made to study circuits that balances the capacitor voltages and a scheme is investigated for balancing the capacitor voltages. Method proposed in [1] uses PID controller for balancing the capacitor voltages. In this project PI based control scheme and artificial neural network (ANN based control scheme for the front end circuit shown in [1] are designed for achieving balance among the capacitor voltages. The proposed control scheme is simulated with the help of Simpowersystems block set and neural network toolbox of MATLAB software for different load conditions. Results obtained from ANN based controller and PI controller are presented.

  5. Voltage Control Method Using Distributed Generators Based on a Multi-Agent System

    Directory of Open Access Journals (Sweden)

    Hyun-Koo Kang

    2015-12-01

    Full Text Available This paper presents a voltage control method using multiple distributed generators (DGs based on a multi-agent system framework. The output controller of each DG is represented as a DG agent, and each voltage-monitoring device is represented as a monitoring agent. These agents cooperate to accomplish voltage regulation through a coordinating agent or moderator. The moderator uses the reactive power sensitivities and margins to determine the voltage control contributions of each DG. A fuzzy inference system (FIS is employed by the moderator to manage the decision-making process. An FIS scheme is developed and optimized to enhance the efficiency of the proposed voltage control process using particle swarm optimization. A simple distribution system with four voltage-controllable DGs is modeled, and an FIS moderator is implemented to control the system. Simulated data show that the proposed voltage control process is able to maintain the system within the operating voltage limits. Furthermore, the results were similar to those obtained using optimal power flow calculations, even though little information on the power system was required and no power flow calculations were implemented.

  6. 基于Multisim10仿真软件的多输出直流稳压电源设计%Design of Multi-Output DC Stabilized Voltage Supply Based on Multisim10

    Institute of Scientific and Technical Information of China (English)

    刘磊; 胡海燕; 李伟达; 李娟; 秦佳

    2013-01-01

    提出了一种多输出线性直流稳压电源的设计,以固定式集成稳压器为核心,可以提供多个固定的直流电压输出。使用EDA软件平台Multisim10对电源设计过程进行仿真分析,针对仿真过程中发现的问题提出解决方案,提高了实验效率。经对电源样机的实验测试,该电源性能良好、工作可靠,输出电压和输出电流、稳压系数和纹波电压均满足设计要求,可以满足实验设备对多种直流电的需要。%This paper raised design of a kind of linear multi-output direct current (DC) stabilized voltage supply, which was based on ifxed type stabilized voltage integrated circuits (ICs), providing multiple ifxed DC voltage outputs. EDA software platform, Multisim 10 was used to simulate and analyze the design process of power supply. In allusion to problems in simulation process, this paper raised settling plan to improve the efifciency of the experiment. The test for the prototype has proved that this type of power supply is good in performance, reliable in work, meeting the design requirements of output voltage, output current, stabilized voltage coefifcient and output ripple voltage, as well as multi-DC requirements for experimental equipment.

  7. Bidirectional dc-to-dc Power Converter

    Science.gov (United States)

    Griesbach, C. R.

    1986-01-01

    Solid-state, series-resonant converter uses high-voltage thyristors. Converter used either to convert high-voltage, low-current dc power to lowvoltage, high current power or reverse. Taking advantage of newly-available high-voltage thyristors to provide better reliability and efficiency than traditional converters that use vacuum tubes as power switches. New converter essentially maintenance free and provides greatly increased mean time between failures. Attractive in industrial applications whether or not bidirectional capability is required.

  8. DC to DC converters: operation; Hacheurs: fonctionnement

    Energy Technology Data Exchange (ETDEWEB)

    Bernot, F. [Ecole d' Ingenieurs de Tours, 37 (France)

    2002-05-01

    This article deals with pulse width modulation (PWM) and pulse position modulation (PPM) DC to DC converters. A tri-phase PWM converter is made of 6 simple DC/DC converters grouped together into 3 reversible converters of the same type: 1 - single-quadrant voltage lowering converters (hydraulic analogy, study with ideal elements, full scheme with input and output filters); 2 - single-quadrant voltage raising converters (hydraulic analogy, operation); 3 - two quadrants reversible converters (structure construction, quadrants of operation, reversible converter connected to a DC motor); 4 - four-quadrants reversible converters; 5 - other converters structure (current converters and converters with intermediate storage, asymmetrical converters, converters with capacitive storage, insulated converters, resonating converters, status); 6 - conclusion. (J.S.)

  9. A fault-tolerant voltage measurement method for series connected battery packs

    Science.gov (United States)

    Xia, Bing; Mi, Chris

    2016-03-01

    This paper proposes a fault-tolerant voltage measurement method for battery management systems. Instead of measuring the voltage of individual cells, the proposed method measures the voltage sum of multiple battery cells without additional voltage sensors. A matrix interpretation is developed to demonstrate the viability of the proposed sensor topology to distinguish between sensor faults and cell faults. A methodology is introduced to isolate sensor and cell faults by locating abnormal signals. A measurement electronic circuit is proposed to implement the design concept. Simulation and experiment results support the mathematical analysis and validate the feasibility and robustness of the proposed method. In addition, the measurement problem is generalized and the condition for valid sensor topology is discovered. The tuning of design parameters are analyzed based on fault detection reliability and noise levels.

  10. Simulation and Implementation of Quasi Resonant DC-DC Converter

    Directory of Open Access Journals (Sweden)

    N. Devarajan

    2012-01-01

    Full Text Available Problem statement: A half-bridge LLC resonant converter with a voltage doubler rectifier has a simple structure and its Zero-Voltage-Switching (ZVS capability is excellent from zero to full load condition. But conduction loss is more due to high circulating energy thus reducing the system efficiency. Moreover a variable frequency control method makes the control circuits more complicated than those using the Pulse Width Modulation (PWM control method. Thus, DC drive has lower efficiency when it operates on light loads. Approach: To improve the efficiency of the DC drive under light loads, a PWM-controlled quasi-resonant converter is proposed .It has simple control circuits and less conduction loss compared to a half-bridge LLC resonant converter under light load conditions. The proposed converter has a half-bridge LLC resonant converter along with an auxiliary circuit. The load regulation of the proposed converter can be achieved by an auxiliary circuit. Thus the proposed converter is expected to be suitable sustaining power module for the efficiency enhancement of DC drives. As the magnetizing inductance of the proposed converter is larger the circulating energy is considerably reduced under light load conditions. In this study the operational principle, design and modeling of QRC DC-DC converters for DC drives are presented. The PWM controlled quasi resonant converter is implemented using PIC microcontroller 16F184A. Results: The capacitor filter in the output is replaced by pi filter to produce DC with minimum ripple. The experimental results and simulation results are compared. This converter has the advantages like reduced number of switches, reduced transformer and filter size, reduced ripple, reduced switching losses, reduced switching stresses and increased power density. Conclusion: The experimental results closely agree with the simulation results.

  11. Fuzzy Recognition of the High-voltage DC Energy Storage Capacitor Defects Based on Partial Discharge%基于直流局部放电的高压储能电容器缺陷的模糊识别

    Institute of Scientific and Technical Information of China (English)

    王鹏; 吴广宁; 张依强; 张血琴

    2011-01-01

    为提高脉冲功率系统中高压储能电容器的可靠性,笔者利用直流下局部放电对电容器进行缺陷检测,得到直流局部放电测量数据的统计谱图,提出基于模糊数学理论识别电容器缺陷类型的方法.首先从22个统计算子中挑选出12个具有典型特征的统计算子组成特征向量,然后通过内部缺陷、接触缺陷、重叠缺陷、油质缺陷4种典型缺陷的测量,计算出每种缺陷特征向量的正态分布隶属函数.最后对未知缺陷类型的电容器进行了模糊检测和解剖验证,对含有可视气泡已知缺陷的电容器进行了检测和模糊识别,证明了系统的实用性,系统可用于脉冲功率系统组装前电容器的可靠性检测.%Defect detection via partial discharge under DC voltage was conducted to enhance the reliability of storage capacitor in high-voltage pulsed power system, and DC partial discharge measurement data were gained. Fuzzy mathematics theory was adopted for capacitor defect type recognition. Firstly, 12 statistical operators from 22 were selected to form the statistical operator characteristic vector. Then each type of defect's characteristic vector membership function with normal distribution was calculated through the measurement of internal defect, contact defect, overlap defect, and oil quality defect, respectively. Finally,two capacitors with respective an unknown defect and a known defect were detected and anatomized to validate the utility of the method. This proposed method can be used for capacitors reliability detection for pulsed power system prior to assembly.

  12. Initial position estimation method for permanent magnet synchronous motor based on improved pulse voltage injection

    DEFF Research Database (Denmark)

    Wang, Z.; Lu, K.; Ye, Y.

    2011-01-01

    According to saliency of permanent magnet synchronous motor (PMSM), the information of rotor position is implied in performance of stator inductances due to the magnetic saturation effect. Researches focused on the initial rotor position estimation of PMSM by injecting modulated pulse voltage...... vectors. The relationship between the inductance variations and voltage vector positions was studied. The inductance variation effect on estimation accuracy was studied as well. An improved five-pulses injection method was proposed, to improve the estimation accuracy by choosing optimaized voltage vectors...

  13. Post-Treatment Process of Extruded Insulation for 400 kV DC High Voltage Cable%400kV直流高压电缆绝缘挤塑后处理工艺

    Institute of Scientific and Technical Information of China (English)

    王坤; 杨德亮; 陆根生

    2013-01-01

    XLPE material is adopted as insulation of most 400 kV DC high voltage cables,but low molecular additives in material become weakness when suffering DC voltage withstanding test,which leads to low yields.The research of post-treatment extruded insulation for 400 kV DC high voltage cable is carried out.The experiment results of low molecular content in XLPE before and after treatment are compared.As a result the post-treatment processing conditions are cleared leading to the yields of finished products being increased from 65 % to 90 %.%400 kV直流高压电缆大多采用交联聚乙烯(XLPE)材料作为绝缘,材料中低分子添加物影响直流耐压试验通过,造成产品成品率较低.为此,针对400 kV直流高压电缆绝缘挤塑后处理工艺开展了研究,通过对处理前后材料中低分子物质含量的检测,明确了后处理工艺条件,产品成品率由65%提高到90%.

  14. KEY COMPARISONS: Final report: SIM regional comparison of ac-dc voltage transfer difference (SIM.EM.K6a, SIM.EM-K9 and SIM.EM-K11)

    Science.gov (United States)

    Campos, Sara; Filipski, Piotr; Izquierdo, Daniel; Afonso, Edson; Landim, Régis P.; Di Lillo, Lucas; Lipe, Thomas

    2009-01-01

    Three comparisons of ac-dc voltage transfer difference held from January to December 2004 are reported. Six NMIs in the SIM region took part: NRC (Canada), NIST (United States of America), CENAM (Mexico), INTI (Argentina), UTE (Uruguay) and INMETRO (Brazil). The comparisons were proposed to assess the measurement capabilities in ac-dc voltage transfer difference of the NMIs in the SIM region. The test points were selected to link the results with the equivalent CCEM Key Comparisons, through three NMIs participating in both SIM and CCEM key comparisons. Additionally, a SIM.EM-Supplementary comparison was proposed, in support of the SIM NMIs' power/energy meter calibration capabilities. One technical protocol and one travelling standard were used, to economize on time and resources. The report shows the degree of equivalence in the SIM region and also the degree of equivalence with the corresponding CCEM reference value. The results of all participants support the values and uncertainties of the applicable CMC entries for ac-dc voltage transfer difference in the Key Comparison Database held at the BIPM. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  15. Effect of n-value on third harmonic voltage method analyzed by finite element method

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, T. [Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820-8502 (Japan); Otabe, E.S. [Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820-8502 (Japan)], E-mail: otabe@cse.kyutech.ac.jp; Matsushita, T. [Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820-8502 (Japan); Okamoto, H. [Kyushu Electric Power Co., Inc., Shiohara 2-1-47, Minamiku, Fukuoka, 815-8520 (Japan)

    2008-09-15

    To investigate the correctness of the estimation of the critical current density J{sub c} in high-T{sub c} superconductor by third harmonic voltage measurement method, the third harmonic voltage V{sub 3} and the distributions of magnetic flux and current in a superconducting film with various n-values are calculated by FEM using the n-value model. When the AC current I{sub 0}cos{omega}t is applied to a coil, the threshold coil current I{sub th}, which is proportional to J{sub c} in the film, is determined by so-called off-set method for V{sub 3}/I{sub 0}-I{sub 0} curve which is frequently used in the four terminal method. The calculated value of I{sub th} is slightly smaller than that of theoretical value by Bean's model. When the coil current I{sub 0} is smaller than I{sub th}, although the current density distribution is almost uniformly distributed as predicted by Bean's model, the value of current density is smaller than J{sub c}. This behavior is different from the prediction of Bean's model. It is found that the current density is uniform and is equal to J{sub c} for high n-value when I{sub 0} is closed to I{sub th}. Therefore, it seems to be reasonable to estimate J{sub c} by I{sub th} in the above method for superconducting films with n-value higher than 20.

  16. A Stochastic Response Surface Method for Probabilistic Evaluation of the Voltage Stability Considering Wind Power

    Institute of Scientific and Technical Information of China (English)

    BAO Haibo; WEI Hua

    2012-01-01

    The traditional voltage stability analysis method is mostly based on the deterministic model, and ignores the uncertainties of bus loads, power supplies, changes in network configuration and so on. However, the great expansion of renewable power generations such as wind and solar energy in a power system has increased their uncertainty, and traditional techniques are limited in capturing their variable behavior. This leads to greater needs of new techniques and methodologies to properly quantify the voltage stability of power systems.

  17. Modelling of stress fields during LFEM DC casting of aluminium billets by a meshless method

    Science.gov (United States)

    Mavrič, B.; Šarler, B.

    2015-06-01

    Direct Chill (DC) casting of aluminium alloys is a widely established technology for efficient production of aluminium billets and slabs. The procedure is being further improved by the application of Low Frequency Electromagnetic Field (LFEM) in the area of the mold. Novel LFEM DC processing technique affects many different phenomena which occur during solidification, one of them being the stresses and deformations present in the billet. These quantities can have a significant effect on the quality of the cast piece, since they impact porosity, hot-tearing and cold cracking. In this contribution a novel local radial basis function collocation method (LRBFCM) is successfully applied to the problem of stress field calculation during the stationary state of DC casting of aluminium alloys. The formulation of the method is presented in detail, followed by the presentation of the tackled physical problem. The model describes the deformations of linearly elastic, inhomogeneous isotropic solid with a given temperature field. The temperature profile is calculated using the in-house developed heat and mass transfer model. The effects of low frequency EM casting process parameters on the vertical, circumferential and radial stress and on the deformation of billet surface are presented. The application of the LFEM appears to decrease the amplitudes of the tensile stress occurring in the billet.

  18. A high reliable DC-DC converter for charging battery%一种蓄电池充电用高可靠性DC-DC变换器

    Institute of Scientific and Technical Information of China (English)

    陶艳

    2012-01-01

    介绍了一种能将直流高压电源变换为直流低压电源,并对蓄电池进行充电和管理的高可靠性的DC-DC变换器.详细说明了DC-DC变换器的技术参数、功能要求及插槽式模块化结构设计方法,着重阐述了开关电源模块的均流控制、充电管理功能及电路原理;归纳总结了变换器高可靠性的冗余设计及其相应保护功能.%A high reliable DC-DC converter which could transform DC high voltage power supply into DC low voltage power supply,charge and manage the battery was introduced in this paper.Its technical parameters,functional requirements and modular structure design method of slots were illustrated for the DC-DC converter,focusing on the load sharing,charging management and circuit theory of the switching power supply modules; the DC-DC converter reliability redundancy design and its corresponding protection were summarized.

  19. Reliability-Oriented Design of LC Filter in Buck DC-DC Converter

    DEFF Research Database (Denmark)

    Liu, Yi; Huang, Meng; Wang, Huai;

    2015-01-01

    State-of-the-art LC filter design of buck DC-DC converter is based on the specifications of voltage and current ripples and constrains in power density and cost. Since lifetime is an important performance factor in reliability critical applications, this digest proposes a method to optimize...... an optimized LC filter design to fulfill the required lifetime. The theoretical analysis and simulation study are presented which are verified by the experimental results from a buck converter prototype....

  20. 3D DC Resistivity Inversion with Topography Based on Regularized Conjugate Gradient Method

    Directory of Open Access Journals (Sweden)

    Jian-ke Qiang

    2013-01-01

    Full Text Available During the past decades, we observed a strong interest in 3D DC resistivity inversion and imaging with complex topography. In this paper, we implemented 3D DC resistivity inversion based on regularized conjugate gradient method with FEM. The Fréchet derivative is assembled with the electric potential in order to speed up the inversion process based on the reciprocity theorem. In this study, we also analyzed the sensitivity of the electric potential on the earth’s surface to the conductivity in each cell underground and introduced an optimized weighting function to produce new sensitivity matrix. The synthetic model study shows that this optimized weighting function is helpful to improve the resolution of deep anomaly. By incorporating topography into inversion, the artificial anomaly which is actually caused by topography can be eliminated. As a result, this algorithm potentially can be applied to process the DC resistivity data collected in mountain area. Our synthetic model study also shows that the convergence and computation speed are very stable and fast.

  1. A Current-Fed Isolated Bidirectional DC-DC Converter

    DEFF Research Database (Denmark)

    Sun, Xiaofeng; Wu, Xiaoying; Shen, Yanfeng;

    2017-01-01

    This paper proposes a current-fed isolated bidirectional DC-DC converter (CF-IBDC) which has the advantages of wide input voltage range, low input current ripple, low conduction losses, and soft switching over the full operating range. Compared with conventional CF-IBDCs, the voltage spikes of th...

  2. An organic integrated capacitive DC-DC up-converter

    NARCIS (Netherlands)

    Marien, H.; Steyaert, M.; Steudel, S.; Vicca, P.; Smout, S.; Gelinck, G.H.; Heremans, P.L.

    2010-01-01

    In this paper a fully integrated organic DC-DC upconverter is presented in a pentacene p-type only technology. This 3-stage Dickson converter reaches a voltage conversion factor of 3 for a purely capacitive load and 2.5 for a 10 μA load current. The maximal output voltage goes up to 75 V and the Dic

  3. Sheppard-Taylor Isolated High Boost DC-DC Converter

    DEFF Research Database (Denmark)

    Chub, Andrii; Siwakoti, Yam Prasad; Vinnikov, Dmitri

    2017-01-01

    This paper presents a new galvanically isolated step-up dc-dc converter intended for low-power but high step-up applications. The proposed converter is capable of regulating output voltage within a wide range of the input voltage or load variations. In contrast to competitors, the converter can b...

  4. Fabrication and characterization of TiN nanocomposite powders fabricated by DC arc-plasma method

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, K., E-mail: kaneko@zaiko.kyushu-u.ac.j [Department of Materials Science and Engineering, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); JST-CREST (Japan); Kitawaki, K. [Department of Materials Science and Engineering, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Sadayama, S. [FEI Company Japan Ltd., NSS-II Bldg 1F, 13-34 Kohnan 2-chome, Minato-ku, Tokyo 108-0075 (Japan); Razavi, H. [Department of Materials Science and Engineering, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Hernandez-Garrido, J.C.; Midgley, P.A. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Okuyama, H.; Uda, M. [Nano Ceramics Center, National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Sakka, Y. [Nano Ceramics Center, National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047 (Japan); WPI Center for MANA, National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2010-03-04

    TiN nanocomposite powders with various morphologies were synthesized by DC arc-plasma method from Ti-Si ingot under N{sub 2}-H{sub 2}-Ar atmosphere. Microstructures of powders were characterized by powder X-ray diffraction method and transmission electron microscopy with compositional analysis, then morphologies by three-dimensional electron tomography. It was found that the powders were consisted of TiN nanoparticles covered by Ti{sub 5}Si{sub 3} nanoparticles, which possibly suppressed the growth of facets and controlled the final morphologies of TiN-Ti{sub 5}Si{sub 3} nanocomposite.

  5. Line-to-line voltage based modulation scheme for single-phase reduced switch ac-dc-ac converters to achieve improved performance

    DEFF Research Database (Denmark)

    Qin, Zian; Loh, Poh Chiang; Blaabjerg, Frede

    2015-01-01

    . With the SVPWM or DPWM proposed in literatures, the generation of the references is phase voltage based. But the phase voltages actually cannot be controlled directly by the PWM converter, since they can be influenced by both of terminal voltages and the load network while the PWM converter can only control...

  6. High voltage MOSFET devices and methods of making the devices

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Sujit; Matocha, Kevin; Chatty, Kiran

    2015-12-15

    A SiC MOSFET device having low specific on resistance is described. The device has N+, P-well and JFET regions extended in one direction (Y-direction) and P+ and source contacts extended in an orthogonal direction (X-direction). The polysilicon gate of the device covers the JFET region and is terminated over the P-well region to minimize electric field at the polysilicon gate edge. In use, current flows vertically from the drain contact at the bottom of the structure into the JFET region and then laterally in the X direction through the accumulation region and through the MOSFET channels into the adjacent N+ region. The current flowing out of the channel then flows along the N+ region in the Y-direction and is collected by the source contacts and the final metal. Methods of making the device are also described.

  7. Radiation Effects on DC-DC Converters

    Science.gov (United States)

    Zhang, De-Xin; AbdulMazid, M. D.; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2001-01-01

    In this work, several DC-DC converters were designed and built. The converters are Buck Buck-Boost, Cuk, Flyback, and full-bridge zero-voltage switched. The total ionizing dose radiation and single event effects on the converters were investigated. The experimental results for the TID effects tests show that the voltages of the Buck Buck-Boost, Cuk, and Flyback converters increase as total dose increased when using power MOSFET IRF250 as a switching transistor. The change in output voltage with total dose is highest for the Buck converter and the lowest for Flyback converter. The trend of increase in output voltages with total dose in the present work agrees with those of the literature. The trends of the experimental results also agree with those obtained from PSPICE simulation. For the full-bridge zero-voltage switch converter, it was observed that the dc-dc converter with IRF250 power MOSFET did not show a significant change of output voltage with total dose. In addition, for the dc-dc converter with FSF254R4 radiation-hardened power MOSFET, the output voltage did not change significantly with total dose. The experimental results were confirmed by PSPICE simulation that showed that FB-ZVS converter with IRF250 power MOSFET's was not affected with the increase in total ionizing dose. Single Event Effects (SEE) radiation tests were performed on FB-ZVS converters. It was observed that the FB-ZVS converter with the IRF250 power MOSFET, when the device was irradiated with Krypton ion with ion-energy of 150 MeV and LET of 41.3 MeV-square cm/mg, the output voltage increased with the increase in fluence. However, for Krypton with ion-energy of 600 MeV and LET of 33.65 MeV-square cm/mg, and two out of four transistors of the converter were permanently damaged. The dc-dc converter with FSF254R4 radiation hardened power MOSFET's did not show significant change at the output voltage with fluence while being irradiated by Krypton with ion energy of 1.20 GeV and LET of 25

  8. Modular high voltage power supply for chemical analysis

    Science.gov (United States)

    Stamps, James F.; Yee, Daniel D.

    2008-07-15

    A high voltage power supply for use in a system such as a microfluidics system, uses a DC-DC converter in parallel with a voltage-controlled resistor. A feedback circuit provides a control signal for the DC-DC converter and voltage-controlled resistor so as to regulate the output voltage of the high voltage power supply, as well as, to sink or source current from the high voltage supply.

  9. Deicing of medium voltage power transmission lines by Joule heating method

    Energy Technology Data Exchange (ETDEWEB)

    Farokhi, S.; Vahidi, B. [Amirkabir Univ. of Technology, Tehran (Iran, Islamic Republic of). Electrical Engineering Dept.

    2005-07-01

    A Joule heating method for the de-icing of overhead transmission lines was presented. The combined use of short circuits and reduced voltage was introduced as as effective method for the de-icing of sub-transmission lines of a utility in Iran. The method is able to melt ice in a short period of time. The required electrical current and the time needed for melting the ice as a function of wind speed, air temperature and ice thickness was determined by using a finite difference heat transfer model which considered the heat flux terms. An algorithm of the application method was proposed using the finite difference heat transfer model and considering steady state radial heat conduction. The required time for melting the accumulated ice on overhead transmission lines for different values of line current and climatic conditions was calculated. In the proposed method, after disconnecting the end of the line, a 3 phase short circuit was applied and accumulated ice was melted because of Joule losses. The main restrictions to the method were the current rating of facilities, and source capacity. After a consideration of these restrictions, instead of feeding the line by rated voltage, a voltage with a value of about 20 to 40 per cent of its rated voltage was applied and a short circuit on the end of the line should be made. The algorithm was made by collecting the data for the power system, disconnecting both ends of the line from the system and applying required changes on loads. transformers calculated from the load flow of the system. The line was fed with the reduced voltage by connecting the line to a lower level voltage. A case study of the method was presented. 10 refs., 1 tab., 4 figs.

  10. High voltage semiconductor devices and methods of making the devices

    Energy Technology Data Exchange (ETDEWEB)

    Matocha, Kevin; Chatty, Kiran; Banerjee, Sujit

    2017-02-28

    A multi-cell MOSFET device including a MOSFET cell with an integrated Schottky diode is provided. The MOSFET includes n-type source regions formed in p-type well regions which are formed in an n-type drift layer. A p-type body contact region is formed on the periphery of the MOSFET. The source metallization of the device forms a Schottky contact with an n-type semiconductor region adjacent the p-type body contact region of the device. Vias can be formed through a dielectric material covering the source ohmic contacts and/or Schottky region of the device and the source metallization can be formed in the vias. The n-type semiconductor region forming the Schottky contact and/or the n-type source regions can be a single continuous region or a plurality of discontinuous regions alternating with discontinuous p-type body contact regions. The device can be a SiC device. Methods of making the device are also provided.

  11. A sensorless control method for capacitor voltage balance and circulating current suppression of modular multilevel converter

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Loh, Poh Chiang

    2015-01-01

    There are several problems in the Modular Multilevel Converter (MMC), such as the appearance of circulating current, capacitor voltage unbalance and the requirement for a high number of sensors. All these problems will decrease the reliability and raise the cost/uncertainty of using MMC solutions....... As a result, a sensorless control method is proposed in this paper, which targets to improve the performances of MMC in respect to the above mentioned disadvantages: To decrease the cost and simplify the physical implementation, a state observer is proposed and designed to estimate both the capacitor voltages...... and the circulating currents in order to replace the high numbers of sensors. Furthermore, a control method combining the circulating current suppression and the capacitor voltage balancing is conducted based on the proposed state observer. It is concluded that the proposed state observer and control method can...

  12. Research on DC voltage and filtering technology on electronic load%电子负载直流侧电压分析及滤波技术研究

    Institute of Scientific and Technical Information of China (English)

    严雪飞; 朱长青; 赵月飞; 安巧静

    2014-01-01

    The DC side as the energy exchange bridge between the input and output plays an important role in the elec‐tronic load system ,the DC voltage maintaining a nominal level can make the whole system stable .This paper first analy‐sis the system structure and then calculate the DC side voltage and harmonic .On this basis ,an IIR notch filter is de‐signed for filtering the harmonics at the DC side .A simulation is made in Matlab/Simulink and it proves that the IIR notch filter is effective on the DC side harmonic filtering .%电子负载的直流侧作为输入、输出能量之间交换的一个桥梁,在系统中起着重要的作用,其直流电压保持一个额定的水平可以使整个系统稳定的运行。在分析系统结构的基础上,从瞬时功率平衡角度出发,对直流侧电压及其谐波进行了分析计算。在此基础上,设计了相应频率的IIR陷波滤波器对直流侧谐波进行滤除。并在Matlab/Simulink中对应用IIR陷波滤波器的电子负载进行仿真,仿真表明,IIR陷波滤波器对直流侧谐波有着良好的滤波效果。

  13. Method and apparatus for controlling LCL converters using asymmetric voltage cancellation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Hunter; Sealy, Kylee Devro; Sharp, Bryan Thomas; Gilchrist, Aaron

    2016-01-26

    A method and apparatus for LCL resonant converter control utilizing Asymmetric Voltage Cancellation is described. The methods to determine the optimal trajectory of the control variables are discussed. Practical implementations of sensing load parameters are included. Simple PI, PID and fuzzy logic controllers are included with AVC for achieving good transient response characteristics with output current regulation.

  14. Permanent Magnet Flux Online Estimation Based on Zero-Voltage Vector Injection Method

    DEFF Research Database (Denmark)

    Xie, Ge; Lu, Kaiyuan; Kumar, Dwivedi Sanjeet;

    2015-01-01

    In this paper, a simple signal injection method is proposed for sensorless control of PMSM at low speed, which ideally requires one voltage vector only for position estimation. The proposed method is easy to implement resulting in low computation burden. No filters are needed for extracting the h...

  15. Suitability of voltage stability study methods for real-time assessment

    DEFF Research Database (Denmark)

    Perez, Angel; Jóhannsson, Hjörtur; Vancraeyveld, Pieter;

    2013-01-01

    This paper analyzes the suitability of existing methods for long-term voltage stability assessment for real-time operation. An overview of the relevant methods is followed with a comparison that takes into account the accuracy, computational efficiency and characteristics when used for security...

  16. DC system voltage alarm settings of nuclear power plants%核电站核岛直流系统电压报警定值分析与设计

    Institute of Scientific and Technical Information of China (English)

    郝连钢; 孙炜

    2011-01-01

    利用RCC-E关于直流系统电压性能异常变化范围的规定,以及现有核岛直流系统蓄电池年度放电曲线,结合法国EDF核电站核岛直流系统电压高低报警定值,提出了1000 MW核电机组核岛直流系统电压高、低报警定值设计的新方法.电压报警定值按照系统设计方法,电压高报警定值与下游电源匹配,电压低报警后,蓄电池应能再运行半个多小时.运行实践表明,新的电压高、低报警定值设计合理,在电压异常时,能够及时报警,正确地反映了系统运行的状况.%The design of high and low alarm settings for the DC system voltage of 1 000 MW nuclear power plants is proposed according to the scope of abnormal voltage performances stipulated in RCC-E for DC system and the existing annual discharge curve of DC system battery,with the reference to those of French EDF nuclear power plants. The designed high alarm setting matches the downstream power supply. With the designed low alarm setting,about more than half an hour of system operation by battery is allowed after alarm annunciation. Operational results show that,the designed voltage alarm settings are reasonable,the voltage abnormality is timely alarmed ,and the situation of the system operation is correctly reflected.

  17. Research on DC-Link Capacitor Voltage Harmonics Reduction of PWM Rectifier Based on Carrier Phase-Shifting%基于载波移相控制的脉冲整流器直流侧支撑电容电压谐波抑制研究

    Institute of Scientific and Technical Information of China (English)

    王娜; 宋文胜; 冯晓云

    2012-01-01

    In the paper, to reduce the DC-link capacitor voltage harmonics of dual-cascading PWM rectifier in electric traction AC drive system, firstly, the theoretical design method of DC-link capacitor was introduced, then, the characteristic of high order harmonics of DC-link voltage in the steady-state was derived, and DC link voltage ripple of the dual-cascading PWM with carrier phase-shifting technology was analyzed in detail. The theoretical analysis showed that the high order ripples of DC-link voltage were mainly distributed around the twice switching frequency, and the carrier phase-shifting technology could reduce these high order ripples to suppress the DC voltage ripple coefficient. Therefore, the DC-link capacitor could be minimized based on traditional design method in combination with carrier phase-shifting technology, Control methods with and without carrier phase-shifting technology were compared in computer simulation and hardware-in-the-loop(HIL) experiment system respectively, which showed the validity and effectiveness of theoretical analysis.%以电力牵引交流传动系统中两重化脉冲整流器拓扑为研究对象,以实现其直流侧支撑电容电压谐波抑制为目标,首先从理论上分析了直流侧支撑电容容量的设计方法;然后分析了稳态运行时直流侧电压高次谐波的产生机理,并重点分析了两重化脉冲整流器载波移相控制方法对直流侧脉动的影响.理论分析表明直流侧电压高次纹波主要分布在2倍开关频率附近,载波移相控制技术可以有效地抑制直流侧2倍开关频率附近的纹波电压,从而减小直流侧电压纹波系数.因此在传统直流侧支撑电容容量设计方法的基础上,加入载波移相控制可以进一步减小所设计的支撑电容大小.最后对未添加载波移相控制和添加载波移相控制的方法分别进行了计算机仿真和半实物试验测试.Matlab仿真和dSPACE半实物测试结果都验证了理

  18. A combined compensation method for the output voltage of an insulated core transformer power supply

    Science.gov (United States)

    Yang, L.; Yang, J.; Liu, K. F.; Qin, B.; Chen, D. Z.

    2014-06-01

    An insulated core transformer (ICT) power supply is an ideal high-voltage generator for irradiation accelerators with energy lower than 3 MeV. However, there is a significant problem that the structure of the segmented cores leads to an increase in the leakage flux and voltage differences between rectifier disks. A high level of consistency in the output of the disks helps to achieve a compact structure by improving the utilization of both the rectifier components and the insulation distances, and consequently increase the output voltage of the power supply. The output voltages of the disks which are far away from the primary coils need to be improved to reduce their inhomogeneity. In this study, by investigating and comparing the existing compensation methods, a new combined compensation method is proposed, which increases the turns on the secondary coils and employs parallel capacitors to improve the consistency of the disks, while covering the entire operating range of the power supply. This method turns out to be both feasible and effective during the development of an ICT power supply. The non-uniformity of the output voltages of the disks is less than 3.5% from no-load to full-load, and the power supply reaches an output specification of 350 kV/60 mA.

  19. Conception de convertisseurs DC/DC à base de MEMS

    OpenAIRE

    Ghandour, Sahar

    2011-01-01

    Current trends towards miniaturization of electronic circuits had led to the advent of System onChip containing different types of circuits indented to perform different functions. These sub-systemsrequire different supply voltages that are delivered from the SoC supply voltage using several DC/DCconverters. Currently, most of the electronic circuits of portable applications use conventional SMPS(switch mode power supply) DC/DC converters containing an inductor element to stock temporally the...

  20. A Generic Topology Derivation Method for Single-phase Converters with Active Capacitive DC-links

    DEFF Research Database (Denmark)

    Wang, Haoran; Wang, Huai; Zhu, Guorong;

    2016-01-01

    capacitive DCDC- link solutions, but important aspects of the topology assess-ment, such as the total energy storage, overall capacitive energy buffer ratio, cost, and reliability are still not available. This paper proposes a generic topology derivation method of single-phase power converters...... with capacitive DC-links, which derives all existing topologies to our best knowledge, and identify a few new topologies. A reliability-oriented design process is applied to compare the cost of different solutions with the lifetime target of 10 years and 35 years, respectively. It reveals that the most cost...

  1. Radiation effects on DC-DC Converters

    Science.gov (United States)

    Zhang, Dexin; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2000-01-01

    DC-DC switching converters are circuits that can be used to convert a DC voltage of one value to another by switching action. They are increasing being used in space systems. Most of the popular DC-DC switching converters utilize power MOSFETs. However power MOSFETs, when subjected to radiation, are susceptible to degradation of device characteristics or catastrophic failure. This work focuses on the effects of total ionizing dose on converter performance. Four fundamental switching converters (buck converter, buck-boost converter, cuk converter, and flyback converter) were built using Harris IRF250 power MOSFETs. These converters were designed for converting an input of 60 volts to an output of about 12 volts with a switching frequency of 100 kHz. The four converters were irradiated with a Co-60 gamma source at dose rate of 217 rad/min. The performances of the four converters were examined during the exposure to the radiation. The experimental results show that the output voltage of the converters increases as total dose increases. However, the increases of the output voltage were different for the four different converters, with the buck converter and cuk converter the highest and the flyback converter the lowest. We observed significant increases in output voltage for cuk converter at a total dose of 24 krad (si).

  2. 多电平变换器直流侧电压平衡控制电路%DC Bus Capacitor Voltage Balancing Circuits in Diode-Clamped Multilevel Converter

    Institute of Scientific and Technical Information of China (English)

    丁娜; 舒泽亮

    2014-01-01

    为解决二极管箝位型多电平变换器直流侧电容电压不平衡的问题,设计了一种带二级辅助电感的平衡控制电路,通过简单控制可以平衡多电平变换器直流侧所有电容的电压。在分析电路结构和控制原理的基础上,从能量转换的角度出发,给出了辅助电感参数选择的范围。以五电平变换器为研究对象,建立了Matlab/Simulink仿真模型,搭建了实验样机,对比分析了本文平衡电路与传统一级平衡控制电路的电容电压平衡特性。实验结果表明,当二级辅助电路工作时,所有直流侧电容电压在20 ms内达到平衡,电容电压的纹波小于3%。%In order to solve the imbalance of DC bus capacitor voltages in the diode-clamped multilevel converter,a balancing circuit with two-layer auxiliary inductors was designed. With this circuit,the voltages of all the DC-side capacitors in the multilevel converter can be balanced by a simple control. On the basis of analysis of the circuit structure and control principle,the ranges of inductor parameters were analyzed from the viewpoint of energy conversion. Taking a five-level converter as an example,a Matlab/Simulink simulation model and an experimental prototype were built,and the balance characteristics of DC bus capacitor voltages were compared between the proposed two-layer auxiliary circuit and the traditional one-layer circuit. Experimental results verify that the proposed two-layer circuit could effectively balance all the DC bus capacitor voltages within 20 ms,and the capacitor voltage ripple was less than 3%.

  3. Non-isolated DC-AC converter with high voltage gain for autonomous systems of electric power; Conversor CC-CA nao isolado com alto ganho de tensao para aplicacao em sistemas autonomos de energia eletrica

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, George Cajazeiras [Centro Federal de Educacao Tecnologica do Ceara (CEFET/CE), Fortaleza, CE (Brazil); Torrico-Bascope, Rene P. [Universidade Federal do Ceara (PPGEE/UFC), Fortaleza, CE (Brazil). Programa de Pos Graduacao em Engenharia Eletrica; Borges Neto, Manuel Rangel [Centro Federal de Educacao Tecnologica de Petrolina (CEFET-PET), PE (Brazil)

    2008-07-01

    A non-isolated DC-AC converter with high voltage gain with two output sinusoidal voltage - 110 V and 220 V - and frequency 60 Hz for application in autonomous systems of electric power is proposed in this work. This topology consists of a boost converter with high voltage gain, based on three-state switching cell combined with a double half bridge inverter. This configuration type the size and the cost are reduced and the efficiency is gotten better, due to the reduced number of switches. The converters that compose this topology operate with high frequency, reducing the volume of the magnetic materials. can be mention as important characteristics: the voltage stress across the switches of the boost converter are low, due they be naturally clamped by one output filter capacitor, which allows the utilization of switches with lower conduction resistances, and the waveforms of the output voltage of the double half bridge inverter supplies for the load it is sinusoidal and it possesses low harmonic content. (author)

  4. Approaches to Suppressing Shaft Voltage in Brushless DC Motor Driven by PWM Inverter Based on Ungrounded Common-Mode Equivalent Circuit

    Science.gov (United States)

    Maetani, Tatsuo; Isomura, Yoshinori; Watanabe, Akihiko; Iimori, Kenichi; Morimoto, Shigeo

    This paper describes an ungrounded common-mode equivalent circuit for a motor driven by a voltage-source PWM inverter. When the capacitance of the rotor was is small, the reversal of the polarities of the common-mode voltage and shaft voltage is observed. In order to model this reversal, a bridge-type equivalent circuit is proposed. On the basis of calculations and experiment, it is found the values and polarity of the shaft voltage can be are accurately determined with the proposed equivalent circuit. Furthermore, the capacitance value of the insulated rotor required to make the shaft voltage equal to or less than the dielectric breakdown voltage of the bearing grease is obtained.

  5. Efficient Low Voltage Amplification Using Self Starting Voltage Regulator for Storage System

    Directory of Open Access Journals (Sweden)

    Haslinah Binti Mohd Nasir

    2014-10-01

    Full Text Available This paper presents a storage system design based on energy harvesting to achieve batteryless for Wireless Sensor Network (WSN application. The storage system is part of the Wireless Sensor Energy Harvesting to store and amplify the energy harvested from the surroundings. Finding a new sources of renewable energy has becomes a fashionable among researchers nowadays in particular harvesting the energy from the surrounding. However the challenge raised is to boost up the energy that known are very low. Thus the proposed method must be consumes very little power and suitable for ambient environmental sources such as vibration, wind and RF energy and be able to boost up the energy for storage system. The output of the harvested voltage is insufficient for most applications, therefore the system will boost up the input voltage level using DC to DC converter topology to higher dc voltage.The DC to DC converter shall be designed to suit the types of storage required. The output voltage of this DC converter should be sufficient to charge either capacitor or supercapacitor that will be use in this system as the energy storage system. The supercapacitor will provide power to energize any system such as in this case wireless sensor network[1]. In the case of wireless sensor network for example, the node would require the energy during transmitting and receiving data only whereas during standby mode or sleep mode, the amount of energy required would be very small[2]. Therefore the storage system will make use of this standby time or sleep mode of the sensor node to store as much energy as possible. The presented DC to DC converter in this paper has high efficiency upto 85.4% with input voltage between range 300mV to 600mV.

  6. Controlling DC Motor using Microcontroller (PIC16F72) with PWM

    OpenAIRE

    Shruti Shrivastava, Jageshwar Rawat, Amit Agrawal

    2012-01-01

    Motion control plays a vital role in industrial atomization. Different types of motors AC, DC, SERVO or stepper are used depending upon the application; of these DC motors are widely used because of easier controlling. Among the different control methods for DC motor armature voltage control method using pulse width modulation (PWM) is best one. We can realize the PWM using H-bridge built with IGBT switches or transistors. To generate PWM signals we use PIC16F7...

  7. Method and apparatus for connecting high voltage leads to a high temperature super-conducting transformer

    Science.gov (United States)

    Golner, Thomas M.; Mehta, Shirish P.

    2005-07-26

    A method and apparatus for connecting high voltage leads to a super-conducting transformer is provided that includes a first super-conducting coil set, a second super-conducting coil set, and a third super-conducting coil set. The first, second and third super-conducting coil sets are connected via an insulated interconnect system that includes insulated conductors and insulated connectors that are utilized to connect the first, second, and third super-conducting coil sets to the high voltage leads.

  8. Improved Thévenin equivalent methods for real-time voltage stability assessment

    DEFF Research Database (Denmark)

    Perez, Angel; Jóhannsson, Hjörtur; Østergaard, Jacob;

    2016-01-01

    An improved Thévenin equivalent method for real-time voltage stability assessment that uses wide-area information from synchrophasors is proposed. The improvements are a better modeling of the limited synchronous generators, and a processing that anticipates the effect of field current limiters, ...

  9. Evaluation of enhancements to Thevenin equivalent based methods for real-time voltage stability assessment

    DEFF Research Database (Denmark)

    Perez, Angel; Jóhannsson, Hjörtur; Østergaard, Jacob

    2014-01-01

    The possibilities offered by the use of Phasor Measurement Units (PMU) in real - time monitoring provide interesting ways to ensure secure operation of power systems. This paper studies the specific case of voltage stability and the possible improvements to the Thevenin equivalent methods, which...

  10. MPP-Tracking DC-DC converters in Photovoltaic applications. Implementation, modeling and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Leppaeaho, J.

    2011-07-01

    voltage-fed converters in photovoltaic interfacing. This thesis presents the generalized dynamic representation of a switched-mode dc-dc converter which can be applied to analyze all possible conversion schemes. The representation makes a clear distinction between the voltage-fed and current-fed conversion schemes and their stability assessment. It is also shown that the current-fed converters can be implemented by applying three different methods based either on intuition, explicit duality transformation or adding a capacitor at the input terminal of a conventional voltage-fed converter. The study includes dynamic characterizations that have not been presented earlier. (orig.)

  11. High impulse voltage and current measurement techniques fundamentals, measuring instruments, measuring methods

    CERN Document Server

    Schon, Klaus

    2013-01-01

    Equipment to be installed in electric power-transmission and distribution systems must pass acceptance tests with standardized high-voltage or high-current test impulses which simulate the stress on the insulation caused by external lightning discharges and switching operations in the grid. High impulse voltages and currents are also used in many other fields of science and engineering for various applications. Therefore, precise impulse-measurement techniques are necessary, either to prevent an over- or understressing of the insulation or to guarantee the effectiveness and quality of the application. The book deals with: principal generator circuits for generating high-voltage and high-current impulses measuring systems and their calibration according to IEC 60060 and IEC 62475 methods of estimating uncertainties of measurement mathematical and experimental basis for characterizing the transfer behavior of spatially extended systems used for measuring fast transients. This book is intended for engineers and ...

  12. Energy Internet Based on Flexible Medium-voltage DC Distribution%基于柔性中压直流配电的能源互联网系统

    Institute of Scientific and Technical Information of China (English)

    赵彪; 赵宇明; 王一振; 刘国伟; 宋强; 袁志昌; 姚森敬

    2015-01-01

    Energy internet is an effective way to achieve large-scale use of renewable energy source, which has tremendous potential. In this paper, the research statuses of the energy internet and DC distribution were introduced; on this basis, the typical topology of AC energy internet was described and analyzed. Then, the energy internet based on flexible medium-voltage DC distribution was presented, and the topology and key technologies were discussed; taking a park in Shenzhen as an example, the application scheme of energy internet based on flexible medium-voltage DC distribution was analyzed. At last, the development prospect of DC energy internet was forecasted.%能源互联网是解决可再生能源大规模利用的有效途径,具有巨大的发展前景.文中对能源互联网和直流配电技术的研究现状进行介绍,在此基础上,对交流能源互联网的典型结构进行论述和分析;给出一种基于柔性中压直流配电的能源互联网系统,对其系统结构和关键技术进行介绍;以深圳某园区为实例,给出基于柔性中压直流配电网的能源互联网的方案示例,为我国能源互联网的建设提供参考.最后,对基于柔性中压直流配电网的能源互联网的发展前景进行了展望.

  13. A hybrid method for optimal load shedding and improving voltage stability

    Directory of Open Access Journals (Sweden)

    V. Tamilselvan

    2016-03-01

    Full Text Available In this paper, a hybrid method is proposed for reducing the amount of load shedding and voltage collapse. The hybrid method is the combination of Genetic Algorithm (GA and Neural Network (NN. The GA is used by two stages, one is to frame the optimization model and other stage is to generate data set for developing the NN based intelligent load shedding model. The appropriate buses for load shedding are selected based on the sensitivity of minimum eigenvalue of load flow Jacobian with respect to the load shed. The proposed method is implemented in MATLAB working platform and the performance is tested with 6 bus and IEEE 14 bus bench mark system. The result of the proposed hybrid method is compared with the GA based optimization algorithm. The comparison shows that, the proposed method ensures voltage stability with minimum loading shedding.

  14. Study on model current predictive control method of PV grid- connected inverters systems with voltage sag

    Science.gov (United States)

    Jin, N.; Yang, F.; Shang, S. Y.; Tao, T.; Liu, J. S.

    2016-08-01

    According to the limitations of the LVRT technology of traditional photovoltaic inverter existed, this paper proposes a low voltage ride through (LVRT) control method based on model current predictive control (MCPC). This method can effectively improve the photovoltaic inverter output characteristics and response speed. The MCPC method of photovoltaic grid-connected inverter designed, the sum of the absolute value of the predictive current and the given current error is adopted as the cost function with the model predictive control method. According to the MCPC, the optimal space voltage vector is selected. Photovoltaic inverter has achieved automatically switches of priority active or reactive power control of two control modes according to the different operating states, which effectively improve the inverter capability of LVRT. The simulation and experimental results proves that the proposed method is correct and effective.

  15. Overview of Multi-DC-Bus Solutions for DC Microgrids

    DEFF Research Database (Denmark)

    Ricchiuto, D.; Mastromauro, R.A.; Liserre, Marco;

    2013-01-01

    DC Microgrids have recently received a lot of attention in the last years due to high penetration of renewable energy sources as well as distributed energy storage systems. In the future DC microgrids could be preferable respect to AC microgrids in terms of redundancy since multi-DC-Bus solutions...... could provide a continuative power supply to the loads. An overview of Multi-DC-Bus solutions is presented in this paper. The performances are compared on the basis of possible DC microgrid configurations, redundancy, different DC voltage levels....

  16. 一种抑制无刷直流电机转矩脉动的新方法%A Method to Suppress Torque Ripple of Brushless DC Motor

    Institute of Scientific and Technical Information of China (English)

    谢少华; 瞿遂春

    2015-01-01

    对无刷直流电机转矩脉动产生的原因进行全面分析,提出增加前级直流变换器抑制转矩脉动的新方法,使用buck直流变换器,通过调整逆变器的母线电压来抑制转矩脉动,在MATLAB/Simulink环境下基于该方法搭建无刷直流电机仿真模型,并对系统进行仿真分析。仿真结果表明,该方法能够有效抑制无刷直流电机转矩脉动。%Analyzes comprehensively the torque ripple causes of brushless DC motor, and proposes a new method of adding the first stage DC converter to control torque ripple. By using buck DC converter and adjusting bus voltage of the inverter to suppress the torque ripple, on the basis establishes brushless DC motor model in MATLAB/Simulink and simulates the system. The result indicates that the method suppresses the torque ripple of brushless DC motor effectively.

  17. Dynamic voltage decoupling compensation control of distributed DC grid converter for permanent magnet wind generator%永磁风力发电机分布式直流并网动态电压解耦补偿控制

    Institute of Scientific and Technical Information of China (English)

    唐任远; 张洪阳; 张志锋; 朱建光

    2011-01-01

    In order to satisfy the demands of distributed DC grid with permanent magnet (synchronous)wind generator, the control strategy of distributed DC grid converter based on dynamic voltage compensation is proposed and studied with wide operation range. The control principle of excitation component was analyzed, and the basis was provided for high performances and so on. The disturbance variable was defined considering the cross coupling and voltage fluctuates based on the coordinate rotary system, and then the system was compensated. The DC chopper circuit was adopted with auxiliary support capacitance for the matching of diffirent DC voltage level. Fnially, the ariable speed constant voltage control of permanent magnet wind generator was implemented. Simulation and experimental vertify the teasibility and validity of the control stategies.%针对永磁(同步)风力发电机分布式直流并网的要求,提出并研究了一种基于机侧电压动态解耦补偿的且具有宽运行范围的分布式直流并网控制策略.分析了永磁风力发电机励磁分量控制原则,进而为电机的高性能运行提供依据.基于同步旋转坐标系把宽范围运行下系统所有的交叉耦合项和电压波动等原因造成的系统扰动统一定义为一个新的变量扰动,然后对控制系统进行补偿.采用辅助支撑电容的直流斩波电路进一步实现不同直流电压等级的匹配,最终实现永磁风力发电机的变速恒压控制.通过仿真和实验验证了控制策略的可行性和有效性.

  18. A passive DC current sensing methodology

    Science.gov (United States)

    Wang, Dong F.; Liu, Huan; Li, Xiaodong; Li, Yang; Xian, Weikang

    2016-10-01

    This paper proposes a method for passive sensing a two-wire DC current without using any cord separator. In this method, a piezoelectric thin-film cantilever with a micro-magnet on its end is positioned near a power cord. The DC current in the power cord induces a magnetic field, which generates a magnetic force acting on the micro-magnet. Consequently, the piezoelectric cantilever is bent and induces an output voltage that is sensitive to small variations of DC currents. A prototype device has been fabricated and experimentally studied. It was found that the initial peak amplitude of the piezoelectric output voltage increases linearly with the DC current value upon "ON-OFF" switching. Compared to the Hall-effect based sensing, this method has the advantages of no need of driving voltage or cord separators even for two-wire appliance cords. Apart from the conventional consumer electronics, this method may have a wide application foreground in the new emerging fields, such as energy vehicles, lithium ion battery, or smart power grid.

  19. Optimal PowerFlow (OPF) Model with Unified AC-DC Load Flow and Optimal Commitmentfor an AC-catenary Railway Power Supply System (RPSS) fed by aHigh Voltage DC (HVDC) transmission line

    OpenAIRE

    Abrahamsson, Lars; Östlund, Stefan; Söder, Lennart

    2012-01-01

    In this paper an alternative railway power systems design based on an HVDC feeder is studied. The HVDC feeder is connected to the catenary by converters. Such an HVDC line is also appropriate for DC-fed railways and AC-fed railways working at public frequency. A unit commitment optimal power flow model has been developed and is applied on a test system. In this paper, the model is presented in detail. The model, in the form of an MINLP program, uses unified AC-DC power flow to minimize the en...

  20. Analysis of electric field control methods for foil coils in high-voltage linear actuators

    Directory of Open Access Journals (Sweden)

    Beek T.A. van

    2015-12-01

    Full Text Available This paper describes multiple electric field control methods for foil coils in high-voltage coreless linear actuators and their sensitivity to misalignment. The investigated field control methods consist of resistive, refractive, capacitive and geometrical solutions for mitigating electric stress at edges and corners of foil coils. These field control methods are evaluated using 2-D boundary element and finite element methods. A comparison is presented between the field control methods and their ability to mitigate electric stress in coreless linear actuators. Furthermore, the sensitivity to misalignment of the field control methods is investigated.