A Voltage Gain-Controlled Modified CFOA And Its Application in Electronically Tunable Four-Mode All-Pass Filter Design

Directory of Open Access Journals (Sweden)

Norbert Herencsar

2012-07-01

Full Text Available This paper presents a new active building block (ABB called voltage gain-controlled modified current feedback amplifier (VGC-MCFOA based on bipolar junction transistor technology. The versatility of the new ABB is demonstrated in new first-order all-pass filter structure design employing single VGC-MCFOA, single grounded capacitor, and three resistors. Introduced circuit provides all four possible transfer functions at the same configuration, namely current-mode, transimpedance-mode, transadmittance-mode, and voltage-mode. The pole frequency of the circuit can be easily tuned by means of DC bias currents. The theoretical results are verified by SPICE simulations based on bipolar transistor arrays AT&T ALA400-CBIC-R process parameters.

A voltage-controlled ring oscillator using InP full enhancement-mode HEMT logic

Energy Technology Data Exchange (ETDEWEB)

Du Rui; Dai Yang; Chen Yanling; Yang Fuhua, E-mail: ddrr@semi.ac.c [Research Center of Semiconductor Integration, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

2009-03-15

A voltage-controlled ring oscillator (VCO) based on a full enhancement-mode InAlAs/InGaAs/InP high electron mobility transistor (HEMT) logic is proposed. An enhancement-mode HEMT (E-HEMT) is fabricated, whose threshold is demonstrated to be 10 mV. The model of the E-HEMT is established and used in the SPICE simulation of the VCO. The result proves that the full E-HEMT logic technology can be applied to the VCO. And compared with the HEMT DCFL technology, the complexity of our fabrication process is reduced and the reliability is improved.

A Comparative Study of Voltage, Peak Current and Dual Current Mode Control Methods for Noninverting Buck-Boost Converter

Directory of Open Access Journals (Sweden)

M. Č. Bošković

2016-06-01

Full Text Available This paper presents a comparison of voltage mode control (VMC and two current mode control (CMC methods of noninverting buck-boost converter. The converter control-to-output transfer function, line-to-output transfer function and the output impedance are obtained for all methods by averaging converter equations over one switching period and applying small-signal linearization. The obtained results are required for the design procedure of feedback compensator to keep a system stable and robust. A comparative study of VMC, peak current mode control (PCMC and dual-current mode control (DCMC is performed. Performance evaluation of the closed-loop system with obtained compensator between these methods is performed via numerical simulations.

Low-voltage analog front-end processor design for ISFET-based sensor and H+ sensing applications

Science.gov (United States)

Chung, Wen-Yaw; Yang, Chung-Huang; Peng, Kang-Chu; Yeh, M. H.

2003-04-01

This paper presents a modular-based low-voltage analog-front-end processor design in a 0.5mm double-poly double-metal CMOS technology for Ion Sensitive Field Effect Transistor (ISFET)-based sensor and H+ sensing applications. To meet the potentiometric response of the ISFET that is proportional to various H+ concentrations, the constant-voltage and constant current (CVCS) testing configuration has been used. Low-voltage design skills such as bulk-driven input pair, folded-cascode amplifier, bootstrap switch control circuits have been designed and integrated for 1.5V supply and nearly rail-to-rail analog to digital signal processing. Core modules consist of an 8-bit two-step analog-digital converter and bulk-driven pre-amplifiers have been developed in this research. The experimental results show that the proposed circuitry has an acceptable linearity to 0.1 pH-H+ sensing conversions with the buffer solution in the range of pH2 to pH12. The processor has a potential usage in battery-operated and portable healthcare devices and environmental monitoring applications.

Frequency to Voltage Converter Analog Front-End Prototype

Science.gov (United States)

Mata, Carlos; Raines, Matthew

2012-01-01

The frequency to voltage converter analog front end evaluation prototype (F2V AFE) is an evaluation board designed for comparison of different methods of accurately extracting the frequency of a sinusoidal input signal. A configurable input stage is routed to one or several of five separate, configurable filtering circuits, and then to a configurable output stage. Amplifier selection and gain, filter corner frequencies, and comparator hysteresis and voltage reference are all easily configurable through the use of jumpers and potentiometers.

Design of auto-control high-voltage control system of pulsed neutron generator

International Nuclear Information System (INIS)

Lv Juntao

2008-01-01

It is difficult to produce multiple anode controlling time sequences under different logging mode for the high-voltage control system of the conventional pulsed neutron generator. It is also difficult realize sequential control among anode high-voltage, filament power supply and target voltage to make neutron yield stable. To these problems, an auto-control high-voltage system of neutron pulsed generator was designed. It not only can achieve anode high-voltage double blast time sequences, which can measure multiple neutron blast time sequences such as Σ, activated spectrum, etc. under inelastic scattering mode, but also can realize neutron generator real-time measurement of multi-state parameters and auto-control such as target voltage pulse width modulation (PWM), filament current, anode current, etc., there by it can produce stable neutron yield and realize stable and accurate measurement of the pulsed neutron full spectral loging tool. (authors)

An improved control method of power electronic converters in low voltage micro-grid

DEFF Research Database (Denmark)

Xiaofeng, Sun; Qingqiu, Lv; Yanjun, Tian

2011-01-01

control of the voltage and frequency deviation added to power references could achieve secondary regulation of the voltage and frequency. In this paper, the authors take the steady and transient transition of grid connecting and disconnecting of the micro-grid as an example, and demonstrate......With the increasing acceptance, micro-grid, combined with distributed generation (DG), may be operated in two modes: grid-connected mode and island mode. In grid connected mode, energy management is the control objective. While in island mode, the control of Voltage and frequency will take...... the place. The conventional droop control can perform the energy management in grid-connected mode, but may not so effective when micro-grid transferring between grid-connected mode and island mode. The paper analysis the micro-grid in different modes (Conventional droop control, Voltage reference...

Voltage-Mode All-Pass Filters Including Minimum Component Count Circuits

Directory of Open Access Journals (Sweden)

Sudhanshu Maheshwari

2007-01-01

Full Text Available This paper presents two new first-order voltage-mode all-pass filters using a single-current differencing buffered amplifier and four passive components. Each circuit is compatible to a current-controlled current differencing buffered amplifier with only two passive elements, thus resulting in two more circuits, which employ a capacitor, a resistor, and an active element, thus using a minimum of active and passive component counts. The proposed circuits possess low output impedance, and hence can be easily cascaded for voltage-mode systems. PSPICE simulation results are given to confirm the theory.

Design of High-Voltage Switch-Mode Power Amplifier Based on Digital-Controlled Hybrid Multilevel Converter

Directory of Open Access Journals (Sweden)

Yanbin Hou

2016-01-01

Full Text Available Compared with conventional Class-A, Class-B, and Class-AB amplifiers, Class-D amplifier, also known as switching amplifier, employs pulse width modulation (PWM technology and solid-state switching devices, capable of achieving much higher efficiency. However, PWM-based switching amplifier is usually designed for low-voltage application, offering a maximum output voltage of several hundred Volts. Therefore, a step-up transformer is indispensably adopted in PWM-based Class-D amplifier to produce high-voltage output. In this paper, a switching amplifier without step-up transformer is developed based on digital pulse step modulation (PSM and hybrid multilevel converter. Under the control of input signal, cascaded power converters with separate DC sources operate in PSM switch mode to directly generate high-voltage and high-power output. The relevant topological structure, operating principle, and design scheme are introduced. Finally, a prototype system is built, which can provide power up to 1400 Watts and peak voltage up to ±1700 Volts. And the performance, including efficiency, linearity, and distortion, is evaluated by experimental tests.

Complete low power controller for high voltage power systems

International Nuclear Information System (INIS)

Sumner, R.; Blanar, G.

1997-01-01

The MHV100 is a custom CMOS integrated circuit, developed for the AMS experiment. It provides complete control for a single channel high voltage (HV) generator and integrates all the required digital communications, D to A and A to D converters, the analog feedback loop and output drivers. This chip has been designed for use in both distributed high voltage systems or for low cost single channel high voltage systems. The output voltage and current range is determined by the external components

Synchronised PWM Schemes for Three-level Inverters with Zero Common-mode Voltage

DEFF Research Database (Denmark)

Oleschuk, Valentin; Blaabjerg, Frede

2002-01-01

This paper presents results of analysis and comparison of novel synchronised schemes of pulsewidth modulation (PWM), applied to three-level voltage source inverters with control algorithms providing elimination of the common-mode voltage. The proposed approach is based on a new strategy of digital...

A Voltage Gain-Controlled Modified CFOA And Its Application in Electronically Tunable Four-Mode All-Pass Filter Design

OpenAIRE

Norbert Herencsar; Jaroslav Koton; Abhirup Lahiri; Bilgin Metin; Kamil Vrba

2012-01-01

This paper presents a new active building block (ABB) called voltage gain-controlled modified current feedback amplifier (VGC-MCFOA) based on bipolar junction transistor technology. The versatility of the new ABB is demonstrated in new first-order all-pass filter structure design employing single VGC-MCFOA, single grounded capacitor, and three resistors. Introduced circuit provides all four possible transfer functions at the same configuration, namely current-mode, transimpedance-mode, transa...

Docking Simulation of the Binding Interactions of Saxitoxin Analogs Produced by the Marine Dinoflagellate Gymnodinium catenatum to the Voltage-Gated Sodium Channel Nav1.4

Directory of Open Access Journals (Sweden)

Lorena M. Durán-Riveroll

2016-05-01

Full Text Available Saxitoxin (STX and its analogs are paralytic alkaloid neurotoxins that block the voltage-gated sodium channel pore (Nav, impeding passage of Na+ ions into the intracellular space, and thereby preventing the action potential in the peripheral nervous system and skeletal muscle. The marine dinoflagellate Gymnodinium catenatum produces an array of such toxins, including the recently discovered benzoyl analogs, for which the mammalian toxicities are essentially unknown. We subjected STX and its analogs to a theoretical docking simulation based upon two alternative tri-dimensional models of the Nav1.4 to find a relationship between the binding properties and the known mammalian toxicity of selected STX analogs. We inferred hypothetical toxicities for the benzoyl analogs from the modeled values. We demonstrate that these toxins exhibit different binding modes with similar free binding energies and that these alternative binding modes are equally probable. We propose that the principal binding that governs ligand recognition is mediated by electrostatic interactions. Our simulation constitutes the first in silico modeling study on benzoyl-type paralytic toxins and provides an approach towards a better understanding of the mode of action of STX and its analogs.

Docking Simulation of the Binding Interactions of Saxitoxin Analogs Produced by the Marine Dinoflagellate Gymnodinium catenatum to the Voltage-Gated Sodium Channel Nav1.4.

Science.gov (United States)

Durán-Riveroll, Lorena M; Cembella, Allan D; Band-Schmidt, Christine J; Bustillos-Guzmán, José J; Correa-Basurto, José

2016-05-06

Saxitoxin (STX) and its analogs are paralytic alkaloid neurotoxins that block the voltage-gated sodium channel pore (Nav), impeding passage of Na⁺ ions into the intracellular space, and thereby preventing the action potential in the peripheral nervous system and skeletal muscle. The marine dinoflagellate Gymnodinium catenatum produces an array of such toxins, including the recently discovered benzoyl analogs, for which the mammalian toxicities are essentially unknown. We subjected STX and its analogs to a theoretical docking simulation based upon two alternative tri-dimensional models of the Nav1.4 to find a relationship between the binding properties and the known mammalian toxicity of selected STX analogs. We inferred hypothetical toxicities for the benzoyl analogs from the modeled values. We demonstrate that these toxins exhibit different binding modes with similar free binding energies and that these alternative binding modes are equally probable. We propose that the principal binding that governs ligand recognition is mediated by electrostatic interactions. Our simulation constitutes the first in silico modeling study on benzoyl-type paralytic toxins and provides an approach towards a better understanding of the mode of action of STX and its analogs.

Analog implementation of an integral resonant control scheme

International Nuclear Information System (INIS)

Pereira, E; Moheimani, S O R; Aphale, S S

2008-01-01

Integral resonant control (IRC) has been introduced as a high performance controller design methodology for flexible structures with collocated actuator–sensor pairs. IRC has a simple structure and is capable of achieving significant damping, over several modes, while guaranteeing closed-loop stability of the system in the presence of unmodeled out-of-bandwidth dynamics. IRC can be an ideal controller for various industrial damping applications, if packaged in a simple easy-to-implement electronic module. This work proposes an analog implementation of the IRC scheme using a single Op-Amp circuit. The objective is to show that with simple analog realization of the modified IRC scheme, it is possible to damp a large number of vibration modes. A brief discussion about the modeling, circuit considerations, implementation and experimental results is presented in order to validate the usefulness and practicality of the proposed analog IRC implementation. (technical note)

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.

Current Mode Control for LLC Series Resonant DC-to-DC Converters

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Jinhaeng Jang

2015-06-01

Full Text Available Conventional voltage mode control only offers limited performance for LLC series resonant DC-to-DC converters experiencing wide variations in operational conditions. When the existing voltage mode control is employed, the closed-loop performance of the converter is directly affected by unavoidable changes in power stage dynamics. Thus, a specific control design optimized at one particular operating point could become unacceptable when the operational condition is varied. This paper presents a new current mode control scheme which could consistently provide good closed-loop performance for LLC resonant converters for the entire operational range. The proposed control scheme employs an additional feedback from the current of the resonant tank network to overcome the limitation of the existing voltage mode control. The superiority of the proposed current mode control over the conventional voltage mode control is verified using an experimental 150 W LLC series resonant DC-to-DC converter.

Near State Vector Selection-Based Model Predictive Control with Common Mode Voltage Mitigation for a Three-Phase Four-Leg Inverter

Directory of Open Access Journals (Sweden)

Abdul Mannan Dadu

2017-12-01

Full Text Available A high computational burden is required in conventional model predictive control, as all of the voltage vectors of a power inverter are used to predict the future behavior of the system. Apart from that, the common mode voltage (CMV of a three-phase four-leg inverter utilizes up to half of the DC-link voltage due to the use of all of the available voltage vectors. Thus, this paper proposes a near state vector selection-based model predictive control (NSV-MPC scheme to mitigate the CMV and reduce computational burden. In the proposed technique, only six active voltage vectors are used in the predictive model, and the vectors are selected based on the position of the future reference vector. In every sampling period, the position of the reference current is used to detect the voltage vectors surrounding the reference voltage vector. Besides the six active vectors, one of the zero vectors is also used. The proposed technique is compared with the conventional control scheme in terms of execution time, CMV variation, and load current ripple in both simulation and an experimental setup. The LabVIEW Field programmable gate array rapid prototyping controller is used to validate the proposed control scheme experimentally, and demonstrate that the CMV can be bounded within one-fourth of the DC-link voltage.

Current and Voltage Mode Multiphase Sinusoidal Oscillators Using CBTAs

Directory of Open Access Journals (Sweden)

M. Sagbas

2013-04-01

Full Text Available Current-mode (CM and voltage-mode (VM multiphase sinusoidal oscillator (MSO structures using current backward transconductance amplifier (CBTA are proposed. The proposed oscillators can generate n current or voltage signals (n being even or odd equally spaced in phase. n+1 CBTAs, n grounded capacitors and a grounded resistor are used for nth-state oscillator. The oscillation frequency can be independently controlled through transconductance (gm of the CBTAs which are adjustable via their bias currents. The effects caused by the non-ideality of the CBTA on the oscillation frequency and condition have been analyzed. The performance of the proposed circuits is demonstrated on third-stage and fifth-stage MSOs by using PSPICE simulations based on the 0.25 µm TSMC level-7 CMOS technology parameters.

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.

A Zero-Voltage Switching Control Strategy for Dual Half-Bridge Cascaded Three-Level DC/DC Converter with Balanced Capacitor Voltages

DEFF Research Database (Denmark)

Liu, Dong; Wang, Yanbo; Chen, Zhe

2017-01-01

The input capacitor's voltages are unbalanced under the conventional control strategy in a dual half-bridge cascaded three-level (TL) DC/DC converter, which would affect the high voltage stresses on the capacitors. This paper proposes a pulse-wide modulation (PWM) strategy with two working modes...... for the dual half-bridge cascaded TL DC/DC converter, which can realize the zero-voltage switching (ZVS). More significantly, a capacitor voltage balance control is proposed by alternating the two working modes of the proposed ZVS PWM strategy, which can eliminate the voltage unbalance on the four input...... capacitors. Therefore, the proposed control strategy can improve the converter's performances in: 1) reducing the switching losses and noises of the power switches; and 2) reducing the voltage stresses on the input capacitors. Finally, the simulation results are conducted to verify the proposed control...

Three-Input Single-Output Voltage-Mode Multifunction Filter with Electronic Controllability Based on Single Commercially Available IC

Directory of Open Access Journals (Sweden)

Supachai Klungtong

2017-01-01

Full Text Available This paper presents a second-order voltage-mode filter with three inputs and single-output voltage using single commercially available IC, one resistor, and two capacitors. The used commercially available IC, called LT1228, is manufactured by Linear Technology Corporation. The proposed filter is based on parallel RLC circuit. The filter provides five output filter responses, namely, band-pass (BP, band-reject (BR, low-pass (LP, high-pass (HP, and all-pass (AP functions. The selection of each filter response can be done without the requirement of active and passive component matching condition. Furthermore, the natural frequency and quality factor are electronically controlled. Besides, the nonideal case is also investigated. The output voltage node exhibits low impedance. The experimental results can validate the theoretical analyses.

Voltage control of a power-frequency E-beam irradiator

International Nuclear Information System (INIS)

Zhou Zhizhong; Hu Shouming; Wang Jun; Guo Honglei; Su Haijun

2012-01-01

Voltage stability and precision are key specifications of an electron beam irradiator. A voltage control system was developed for smooth high voltage regulating on a power frequency electron accelerator. Pillar variac driven by servo motor was used as the regulating device, with a programmable logic controller as the control unit. An industrial PC was employed to realize human-machine interaction. Open-loop and closed-loop modes were employed to regulate the high voltage. Experimental results show that the speed, stability and precision for high voltage regulating were improved greatly, hence a much better performance of the electron accelerator. (authors)

Study on Control Scheme for the Inverters in Low Voltage Microgrid with Nonlinear Loads

Science.gov (United States)

Xu, Jiqiang; Lu, Wenzhou; Wu, Lei

2017-05-01

There are a lot of nonlinear loads in real low voltage microgrid system. It will cause serious output voltage and grid current harmonic distortions problems in island and grid-connected modes, respectively. To solve this problem, this paper proposes a droop control scheme with quasi-proportion and resonant (quasi-PR) controller based on αβ stationary reference frame to make microgrid smoothly switch between grid-connected and island modes without changing control method. Moreover, in island mode, not only stable output voltage and frequency, but also reduced output voltage harmonics with added nonlinear loads can be achieved; In grid-connected mode, not only constant power, but also reduced grid current harmonics can be achieved. Simulation results verify the effectiveness of the proposed control scheme.

Voltage Mode Universal Biquad Using CCCII

Directory of Open Access Journals (Sweden)

Ashish Ranjan

2011-01-01

Full Text Available This paper proposes a multi-input single-output (MISO second-order active-C voltage mode (VM universal filter using two second-generation current-controlled current conveyors (CCCIIs and two equal-valued capacitors. The proposed circuit realizes low pass, band pass, high pass, all pass, and notch responses from the same topology. The filter uses-minimum number of passive components and no resistor which is suitable for IC Design. The filter enjoys low-sensitivity performance and exhibits electronic and orthogonal tunability of pole frequency (0 and quality factor (0 via bias current of CCCIIs. PSPICE simulation results confirm the theory.

Multifunction Voltage-Mode Filter Using Single Voltage Differencing Differential Difference Amplifier

Directory of Open Access Journals (Sweden)

Chaichana Amornchai

2017-01-01

Full Text Available In this paper, a voltage mode multifunction filter based on single voltage differencing differential difference amplifier (VDDDA is presented. The proposed filter with three input voltages and single output voltage is constructed with single VDDDA, two capacitors and two resistors. Its quality factor can be adjusted without affecting natural frequency. Also, the natural frequency can be electronically tuned via adjusting of bias current. The filter can offer five output responses, high-pas (HP, band-pass (BP, band-reject (BR, low-pass (LP and all-ass (AP functions in the same circuit topology. The output response can be selected by choosing the suitable input voltage without the component matching condition and the requirement of additional double gain voltage amplifier. PSpice simulation results to confirm an operation of the proposed filter correspond to the theory.

Voltage control of cavity magnon polariton

Energy Technology Data Exchange (ETDEWEB)

Kaur, S., E-mail: kaurs3@myumanitoba.ca; Rao, J. W.; Gui, Y. S.; Hu, C.-M., E-mail: hu@physics.umanitoba.ca [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Yao, B. M. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); National Laboratory for Infrared Physics, Chinese Academy of Sciences, Shanghai 200083 (China)

2016-07-18

We have experimentally investigated the microwave transmission of the cavity-magnon-polariton (CMP) generated by integrating a low damping magnetic insulator onto a 2D microwave cavity. The high tunability of our planar cavity allows the cavity resonance frequency to be precisely controlled using a DC voltage. By appropriately tuning the voltage and magnetic bias, we can observe the cavity photon magnon coupling and the magnetic coupling between a magnetostatic mode and the generated CMP. The dispersion of the generated CMP was measured by either tuning the magnetic field or the applied voltage. This electrical control of CMP may open up avenues for designing advanced on-chip microwave devices that utilize light-matter interaction.

Coordinated Voltage Control of a Wind Farm based on Model Predictive Control

DEFF Research Database (Denmark)

Zhao, Haoran; Wu, Qiuwei; Guo, Qinglai

2016-01-01

This paper presents an autonomous wind farm voltage controller based on Model Predictive Control (MPC). The reactive power compensation and voltage regulation devices of the wind farm include Static Var Compensators (SVCs), Static Var Generators (SVGs), Wind Turbine Generators (WTGs) and On...... are calculated based on an analytical method to improve the computation efficiency and overcome the convergence problem. Two control modes are designed for both voltage violated and normal operation conditions. A wind farm with 20 wind turbines was used to conduct case studies to verify the proposed coordinated...

Three-Level Inverters with Common-Mode Voltage Cancellation Based on Synchronous Pulsewidth Modulation

DEFF Research Database (Denmark)

Oleschuk, Valentin; Blaabjerg, Frede

2002-01-01

A novel method of direct synchronous pulse-width modulation (PWM) is disseminated to three-level voltage source inverters with control algorithms with elimination of the common-mode voltages in three-phase drive systems with PWM. It provides smooth pulses-ratio changing and a quarter-wave symmetry...... of the voltage waveforms during the whole control range including overmodulation. Continuous, discontinuous and "direct-direct" schemes of synchronous PWM with both algebraic and trigonometric control functions have been analysed and compared. Simulations give the behaviour of the proposed methods and show some...... advantages of synchronous PWM in comparison with asynchronous at low ratios between the switching frequency and fundamental frequency....

DC Voltage Droop Control Structures and its Impact on the Interaction Modes in Interconnected AC-HVDC Systems

DEFF Research Database (Denmark)

Thams, Florian; Chatzivasileiadis, Spyros; Eriksson, Robert

2017-01-01

Different dc voltage droop control structures for future multi-terminal HVDC systems have been proposed in literature. This paper contributes to the evaluation of those structures by an analysis of their impact on the coupling of the interconnected subsystems. In particular, the modes...... of the systems are classified in different subsets according to the participation of the various subsystems. Those subsets are then evaluated qualitatively and quantitatively indicating which impact the choice of the droop control structure has on the degree of coupling between the connected ac and dc systems...

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

Design and implementation of a new modified sliding mode controller for grid-connected inverter to controlling the voltage and frequency.

Science.gov (United States)

Ghanbarian, Mohammad Mehdi; Nayeripour, Majid; Rajaei, Amirhossein; Mansouri, Mohammad Mahdi

2016-03-01

As the output power of a microgrid with renewable energy sources should be regulated based on the grid conditions, using robust controllers to share and balance the power in order to regulate the voltage and frequency of microgrid is critical. Therefore a proper control system is necessary for updating the reference signals and determining the proportion of each inverter in the microgrid control. This paper proposes a new adaptive method which is robust while the conditions are changing. This controller is based on a modified sliding mode controller which provides adapting conditions in linear and nonlinear loads. The performance of the proposed method is validated by representing the simulation results and experimental lab results. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Uncertainty estimation of non-ideal analog switches using programmable Josephson voltage standards for mutual inductance measurement in the joule balance

International Nuclear Information System (INIS)

Wang, Gang; Zhang, Zhonghua; Li, Zhengkun; Xu, Jinxin; You, Qiang

2016-01-01

Measurement of the mutual inductance is one of the key techniques in the joule balance to determine the Planck constant h, where a standard-square-wave compensation method was proposed to accurately measure the dc value of the mutual inductance. With this method, analog switches are used to compose an analog-switch signal generator to synthesize the excitation and compensation voltages. However, the accuracy of the compensation voltage is influenced by the non-ideal behaviors of analog-switches. In this paper, the effect from these non-ideal switches is analyzed in detail and evaluated with the equivalent circuits. A programmable Josephson voltage standard (PJVS) is used to generate a reference compensation voltage to measure the time integration of the voltage waveform generated by the analog-switch signal generator. Moreover, the effect is also evaluated experimentally by comparing the difference between the mutual inductance measured with the analog-switch signal generator and the value determined by the PJVS-analog-switch generator alternately in the same mutual inductance measurement system. The result shows that the impact of analog switches is 1.97  ×  10 −7 with an uncertainty of 1.83  ×  10 −7 (k  =  1) and confirms that the analog switch method can be used regularly instead of the PJVS in the mutual inductance measurement for the joule balance experiment. (paper)

Sliding-mode control of single input multiple output DC-DC converter

Science.gov (United States)

Zhang, Libo; Sun, Yihan; Luo, Tiejian; Wan, Qiyang

2016-10-01

Various voltage levels are required in the vehicle mounted power system. A conventional solution is to utilize an independent multiple output DC-DC converter whose cost is high and control scheme is complicated. In this paper, we design a novel SIMO DC-DC converter with sliding mode controller. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage DC bus and middle-voltage output terminals, which endow the converter with characteristics of simple structure, low cost, and convenient control. In addition, the sliding mode control (SMC) technique applied in our converter can enhance the performances of a certain SIMO DC-DC converter topology. The high-voltage DC bus can be regarded as the main power source to the high-voltage facility of the vehicle mounted power system, and the middle-voltage output terminals can supply power to the low-voltage equipment on an automobile. In the respect of control algorithm, it is the first time to propose the SMC-PID (Proportion Integration Differentiation) control algorithm, in which the SMC algorithm is utilized and the PID control is attended to the conventional SMC algorithm. The PID control increases the dynamic ability of the SMC algorithm by establishing the corresponding SMC surface and introducing the attached integral of voltage error, which endow the sliding-control system with excellent dynamic performance. At last, we established the MATLAB/SIMULINK simulation model, tested performance of the system, and built the hardware prototype based on Digital Signal Processor (DSP). Results show that the sliding mode control is able to track a required trajectory, which has robustness against the uncertainties and disturbances.

Effects of load voltage on voltage breakdown modes of electrical exploding aluminum wires in air

Energy Technology Data Exchange (ETDEWEB)

Wu, Jian; Li, Xingwen, E-mail: xwli@mail.xjtu.edu.cn; Yang, Zefeng; Wang, Kun; Chao, Youchuang; Shi, Zongqian; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China)

2015-06-15

The effects of the load voltage on the breakdown modes are investigated in exploding aluminum wires driven by a 1 kA, 0.1 kA/ns pulsed current in air. From laser probing images taken by laser shadowgraphy, schlieren imaging, and interferometry, the position of the shockwave front, the plasma channel, and the wire core edge of the exploding product can be determined. The breakdown mode makes a transition from the internal mode, which involves breakdown inside the wire core, to the shunting mode, which involves breakdown in the compressed air, with decreasing charging voltage. The breakdown electrical field for a gaseous aluminum wire core of nearly solid density is estimated to be more than 20 kV/cm, while the value for gaseous aluminum of approximately 0.2% solid density decreases to 15–20 kV/cm. The breakdown field in shunting mode is less than 20 kV/cm and is strongly affected by the vaporized aluminum, the desorbed gas, and the electrons emitted from the wire core during the current pause. Ohmic heating during voltage collapses will induce further energy deposition in the current channel and thus will result in different expansion speeds for both the wire core and the shockwave front in the different modes.

130 kV 130 A high voltage switching mode power supply for neutral beam injectors-Control issues and algorithms

International Nuclear Information System (INIS)

Ganuza, D.; Garcia, F.; Zulaika, M.; Perez, A.; Jones, T.T.C.

2005-01-01

The company JEMA has delivered to the Joint European Torus (JET facility in Culham) two high voltage switching mode power supplies (HVSMPS) each rated 130 kVdc and 130 A. One HVSMPS feeds the grids of two PINI loads. This paper describes the main control issues and the algorithms developed for the project. The most demanding requirements from the control point of view is an absolute accuracy of ±1300 V and the possibility of performing up to 255 re-applications of the high voltage during a 20 s pulse. Keeping the output voltage ripple to the specified tolerance has been a major achievement of the control system. Since the output stage is formed of several modules (120) connected in series, their stray capacitance to ground significantly influences the individual contribution of each single module to the global output voltage. Two complementary techniques have been used to balance the effects of the stray capacities. The fast re-applications requirement has a significant impact on the intermediate dc link. This section is composed of a capacity of 0.83 F, which feeds the 120 invertor modules. The dc link is fed by a 12 pulse SCR rectifier, whose matching transformers are connected to the 36 kV grid. Every re-application and every voltage shutdown supposes a quasi-instantaneous power step of 17 MW. Fast open loop algorithms have been implemented in order to keep the dc link voltage within acceptable margins. Moreover, the HVSMPS output characteristics have to be maintained during the rapid and important voltage fluctuations of the 36 kV mains (28-37 kV). The general control system is based on a Simatic S7 PLC, and a SCADA user interface. Up to 1000 signals are acquired. The control system has shown to be also a useful tool to allow for a rapid and accurate identification of faults and their origin

Analog Amplitude Modulation of a High Voltage, Solid State Inductive Adder, Pulse Generator Using MOSFETS

International Nuclear Information System (INIS)

Gower, E J; Sullivan, J S

2002-01-01

High voltage, solid state, inductive adder, pulse generators have found increasing application as fast kicker pulse modulators for charged particle beams. The solid state, inductive adder, pulse generator is similar in operation to the linear induction accelerator. The main difference is that the solid state, adder couples energy by transformer action from multiple primaries to a voltage summing stalk, instead of an electron beam. Ideally, the inductive adder produces a rectangular voltage pulse at the load. In reality, there is usually some voltage variation at the load due to droop on primary circuit storage capacitors, or, temporal variations in the load impedance. Power MOSFET circuits have been developed to provide analog modulation of the output voltage amplitude of a solid state, inductive adder, pulse generator. The modulation is achieved by including MOSFET based, variable subtraction circuits in the multiple primary stack. The subtraction circuits can be used to compensate for voltage droop, or, to tailor the output pulse amplitude to provide a desired effect in the load. Power MOSFET subtraction circuits have been developed to modulate short, temporal (60-400 ns), voltage and current pulses. MOSFET devices have been tested up to 20 amps and 800 Volts with a band pass of 50 MHz. An analog modulation cell has been tested in a five cell high, voltage adder stack

Simple DCM or CRM analog peak current controller for HV capacitor charge-discharge applications

DEFF Research Database (Denmark)

Trintis, Ionut; Dimopoulos, Emmanouil; Munk-Nielsen, Stig

2013-01-01

This paper presents a simple analog current controller suitable for buck and boost converter topologies. The controller operates in DCM or CRM, depending on the setup. The experimental results are presented to validate the proposed controller functionality for a high voltage capacitor charge...

Low-Power, Low-Voltage Analog to Digital ΣΔ

DEFF Research Database (Denmark)

Wismar, Ulrik Sørensen

2007-01-01

, and since long operation time is required, low supply voltage and low power consumption are of paramount importance. Consequently, various topologies have been compared to nd the most power ecient audio frequency modulator topology. Chapter 4 of this thesis compares power consumption of two of the most...... prevalent topologies, the single-loop modulator with integration in discrete time and the single-loop modulator with integration in continuous time. Both modulator topologies are with feedback, and all intermediate signals are in the voltage mode. Chapter 5 treats a modulator without feedback. Another...

Voltage regulation of the Y-source boost DC-DC converter considering effects of leakage inductances based on cascaded sliding-mode control

DEFF Research Database (Denmark)

Ahmadzadeh, Soheil; Markadeh, Gholamreza Arab; Blaabjerg, Frede

2017-01-01

In this study, a sliding mode-based controller is designed for regulating the output voltage of a high step-up DC-DC converter with three coupled inductors called Y-source impedance network. As Y-source converter can provide a very high boost at a lower shoot-through duty cycle of the switch...

A Virtual Inertia Control Strategy for DC Microgrids Analogized with Virtual Synchronous Machines

DEFF Research Database (Denmark)

Wu, Wenhua; Chen, Yandong; Luo, An

2017-01-01

In a DC microgrid (DC-MG), the dc bus voltage is vulnerable to power fluctuation derived from the intermittent distributed energy or local loads variation. In this paper, a virtual inertia control strategy for DC-MG through bidirectional grid-connected converters (BGCs) analogized with virtual...... synchronous machine (VSM) is proposed to enhance the inertia of the DC-MG, and to restrain the dc bus voltage fluctuation. The small-signal model of the BGC system is established, and the small-signal transfer function between the dc bus voltage and the dc output current of the BGC is deduced. The dynamic...... for the BGC is introduced to smooth the dynamic response of the dc bus voltage. By analyzing the control system stability, the appropriate virtual inertia control parameters are selected. Finally, simulations and experiments verified the validity of the proposed control strategy....

Supplementary High-Input Impedance Voltage-Mode Universal Biquadratic Filter Using DVCCs

Directory of Open Access Journals (Sweden)

Jitendra Mohan

2012-01-01

Full Text Available To further extend the existing knowledge on voltage-mode universal biquadratic filter, in this paper, a new biquadratic filter circuit with single input and multiple outputs is proposed, employing three differential voltage current conveyors (DVCCs, three resistors, and two grounded capacitors. The proposed circuit realizes all the standard filter functions, that is, high-pass, band-pass, low-pass, notch, and all-pass filters simultaneously. The circuit enjoys the feature of high-input impedance, orthogonal control of resonance angular frequency (o, and quality factor (Q via grounded resistor and the use of grounded capacitors which is ideal for IC implementation.

Device and methods for writing and erasing analog information in small memory units via voltage pulses

Science.gov (United States)

El Gabaly Marquez, Farid; Talin, Albert Alec

2018-04-17

Devices and methods for non-volatile analog data storage are described herein. In an exemplary embodiment, an analog memory device comprises a potential-carrier source layer, a barrier layer deposited on the source layer, and at least two storage layers deposited on the barrier layer. The memory device can be prepared to write and read data via application of a biasing voltage between the source layer and the storage layers, wherein the biasing voltage causes potential-carriers to migrate into the storage layers. After initialization, data can be written to the memory device by application of a voltage pulse between two storage layers that causes potential-carriers to migrate from one storage layer to another. A difference in concentration of potential carriers caused by migration of potential-carriers between the storage layers results in a voltage that can be measured in order to read the written data.

Stability Boundaries for Offshore Wind Park Distributed Voltage Control

DEFF Research Database (Denmark)

Gryning, Mikkel P.S.; Wu, Qiuwei; Kocewiak, Lukasz

2017-01-01

pilot control. Using data from the actual wind power plant, all stabilizing subsystem voltage proportional-integral controller parameters are first characterized based on their Hurwitz signature. Inner loop current control is then designed using Internal Mode Control principles, and guidelines for feed......In order to identify mechanisms causing slow reactive power oscillations observed in an existing offshore wind power plant, and be able to avoid similar events in the future, voltage control is studied in this paper for a plant with a static synchronous compensator, type-4 wind turbines and a park...... forward filter design are given to obtain required disturbance rejection properties. The paper contributes by providing analytical relations between power plant control, droop, sampling time, electrical parameters and voltage control characteristics, and by assessing frequencies and damping of reactive...

A time to voltage converter and analog memory unit for straw tracking detectors

International Nuclear Information System (INIS)

Callewaert, L.; Eyckmans, W.; Sansen, W.; Stevens, A.; Van der Spiegel, J.; Van Berg, R.; Williams, H.H.; Yau, T.Y.

1990-01-01

In a high precision drift tube or straw tracking system, one measures the time of arrival of the first electron at the anode. While many possible schemes exist, the authors initial judgment was that an analog time measurement would offer both lower power and greater resolution than an equally complex digital system. In addition, they believe that it will be necessary to incorporate all of the system features such as connection to the trigger and DAQ systems in any usable design in order to keep the power, mass and complexity of the final system under control. A low power, sub-nanosecond accuracy, quick recovery, data-driven, multiple sample Time to Voltage Converter suitable for use on high rate straw tracking detectors is described. The described TVC includes virtual storage of analog data in both Level 1 and Level 2 queues and an on board ADC with first order correction for capacitance variations and non-linearities

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. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Iaverage current mode (ACM) control for switching power converters

OpenAIRE

2014-01-01

Providing a fast current sensor direct feedback path to a modulator for controlling switching of a switched power converter in addition to an integrating feedback path which monitors average current for control of a modulator provides fast dynamic response consistent with system stability and average current mode control. Feedback of output voltage for voltage regulation can be combined with current information in the integrating feedback path to limit bandwidth of the voltage feedback signal.

Current Mode Control for LLC Series Resonant DC-to-DC Converters

OpenAIRE

Jinhaeng Jang; Syam Kumar Pidaparthy; Byungcho Choi

2015-01-01

Conventional voltage mode control only offers limited performance for LLC series resonant DC-to-DC converters experiencing wide variations in operational conditions. When the existing voltage mode control is employed, the closed-loop performance of the converter is directly affected by unavoidable changes in power stage dynamics. Thus, a specific control design optimized at one particular operating point could become unacceptable when the operational condition is varied. This paper presents a...

Voltage Harmonic Compensation of a Microgrid Operating in Islanded and Grid-Connected Modes

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Jalilian, Alireza; Vasquez, Juan C.

2011-01-01

In this paper, a method for voltage harmonic compensation in a microgrid operating in islanded and gridconnected modes is presented. Harmonic compensation is done through proper control of distributed generators (DGs) interface converters. In order to achieve proper sharing of the compensation...

OFCC based voltage and transadmittance mode instrumentation amplifier

Science.gov (United States)

Nand, Deva; Pandey, Neeta; Pandey, Rajeshwari; Tripathi, Prateek; Gola, Prashant

2017-07-01

The operational floating current conveyor (OFCC) is a versatile active block due to the availability of both low and high input and output impedance terminals. This paper addresses the realization of OFCC based voltage and transadmittance mode instrumentation amplifiers (VMIA and TAM IA). It employs three OFCCs and seven resistors. The transadmittance mode operation can easily be obtained by simply connecting an OFCC based voltage to current converter at the output. The effect of non-idealities of OFCC, in particular finite transimpedance and tracking error, on system performance is also dealt with and corresponding mathematical expressions are derived. The functional verification is performed through SPICE simulation using CMOS based implementation of OFCC.

Power supply control system for experimental physical facilities

International Nuclear Information System (INIS)

Zelepukin, S.A.; Osipov, Eh.V.; Petrov, V.S.; Sergeev, V.A.; Uglekov, V.Ya.

1979-01-01

A multichannel (to 1024 channels) system for control of power supply voltage is descrited. The system consists of an analog commulator, a digital voltmeter and a special controller. The controller serves at the same time as an interface for connecting the system as a ''unit'' of the VECTOR and SUMMA unified electronic systems. The system has been realized for control of the photomultiplier power supply voltage of the MARK multipurpose experimental device (256 channels, the measurement accuracy is 0.2%, the measuring time is 500 ms per point). Software devised for the HP-2100 computer permits automatical comparison of photomultiplier power supply voltages with sample ones in the mode of continuous control of a single voltage or in the mode of programmed selection of voltages to provide the control in arbitrary order or automatic scanning

Active Power Factor Correction Using a Sliding Mode Controller

Directory of Open Access Journals (Sweden)

Korhan KAYIŞLI

2008-03-01

Full Text Available In this paper, a sliding mode controller is designed for active shaping of the input current in the boost converter. Robustness of the designed controller is tested with variable output voltage references, different loads and network voltage variations. For the simulations, MATLAB/Simulink programme is used. From simulation results, the same phase was provided between input current and input voltage and nearly unity power factor was obtained.

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.

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.

Trap Healing for High-Performance Low-Voltage Polymer Transistors and Solution-Based Analog Amplifiers on Foil.

Science.gov (United States)

Pecunia, Vincenzo; Nikolka, Mark; Sou, Antony; Nasrallah, Iyad; Amin, Atefeh Y; McCulloch, Iain; Sirringhaus, Henning

2017-06-01

Solution-processed semiconductors such as conjugated polymers have great potential in large-area electronics. While extremely appealing due to their low-temperature and high-throughput deposition methods, their integration in high-performance circuits has been difficult. An important remaining challenge is the achievement of low-voltage circuit operation. The present study focuses on state-of-the-art polymer thin-film transistors based on poly(indacenodithiophene-benzothiadiazole) and shows that the general paradigm for low-voltage operation via an enhanced gate-to-channel capacitive coupling is unable to deliver high-performance device behavior. The order-of-magnitude longitudinal-field reduction demanded by low-voltage operation plays a fundamental role, enabling bulk trapping and leading to compromised contact properties. A trap-reduction technique based on small molecule additives, however, is capable of overcoming this effect, allowing low-voltage high-mobility operation. This approach is readily applicable to low-voltage circuit integration, as this work exemplifies by demonstrating high-performance analog differential amplifiers operating at a battery-compatible power supply voltage of 5 V with power dissipation of 11 µW, and attaining a voltage gain above 60 dB at a power supply voltage below 8 V. These findings constitute an important milestone in realizing low-voltage polymer transistors for solution-based analog electronics that meets performance and power-dissipation requirements for a range of battery-powered smart-sensing applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of voltage sags on digitally controlled line connected switched-mode power supplies

DEFF Research Database (Denmark)

Török, Lajos; Munk-Nielsen, Stig

2012-01-01

Different voltage disorders like voltage fluctuations, sags, frequency variations may occur in the power supply networks due to different fault conditions. These deviations from normal operation affects in different ways the line connected devices. Standards were developed to protect and ensure...... of voltage sags is analyzed. Fault tolerant control algorithm was designed, implemented and is discussed. The fault conditions and their effects were investigated at different power levels....

A PURE NODAL-ANALYSIS METHOD SUITABLE FOR ANALOG CIRCUITS USING NULLORS

OpenAIRE

E. Tlelo-Cuautle; L.A. Sarmiento-Reyes

2003-01-01

A novel technique suitable for computer-aided analysis of analog integrated circuits (ICs) is introduced. This technique uses the features of both nodal-analysis (NA) and symbolic analysis, at nullor level. First, the nullor is used to model the ideal behavior of several analog devices, namely: transistors, opamps, OTAs, and current conveyors. From this modeling approach, it is shown how to transform circuits working in voltage-mode to current-mode and vice-versa. Second, it is demonstrated t...

Integrated Circuits for Analog Signal Processing

CERN Document Server

2013-01-01

  This book presents theory, design methods and novel applications for integrated circuits for analog signal processing.  The discussion covers a wide variety of active devices, active elements and amplifiers, working in voltage mode, current mode and mixed mode.  This includes voltage operational amplifiers, current operational amplifiers, operational transconductance amplifiers, operational transresistance amplifiers, current conveyors, current differencing transconductance amplifiers, etc.  Design methods and challenges posed by nanometer technology are discussed and applications described, including signal amplification, filtering, data acquisition systems such as neural recording, sensor conditioning such as biomedical implants, actuator conditioning, noise generators, oscillators, mixers, etc.   Presents analysis and synthesis methods to generate all circuit topologies from which the designer can select the best one for the desired application; Includes design guidelines for active devices/elements...

Reference-Free CMOS Pipeline Analog-to-Digital Converters

CERN Document Server

Figueiredo, Michael; Evans, Guiomar

2013-01-01

This book shows that digitally assisted analog-to-digital converters are not the only way to cope with poor analog performance caused by technology scaling. It describes various analog design techniques that enhance the area and power efficiency without employing any type of digital calibration circuitry. These techniques consist of self-biasing for PVT enhancement, inverter-based design for improved speed/power ratio, gain-of-two obtained by voltage sum instead of charge redistribution, and current-mode reference shifting instead of voltage reference shifting. Together, these techniques allow enhancing the area and power efficiency of the main building blocks of a multiplying digital-to-analog converter (MDAC) based stage, namely, the flash quantizer, the amplifier, and the switched capacitor network of the MDAC. Complementing the theoretical analyses of the various techniques, a power efficient operational transconductance amplifier is implemented and experimentally characterized. Furthermore, a medium-low ...

An Ultra-Low Voltage Analog Front End for Strain Gauge Sensory System Application in 0.18µm CMOS

Science.gov (United States)

Edward, Alexander; Chan, Pak Kwong

This paper presents analysis and design of a new ultra-low voltage analog front end (AFE) dedicated to strain sensor applications. The AFE, designed in 0.18µm CMOS process, features a chopper-stabilized instrumentation amplifier (IA), a balanced active MOSFET-C 2nd order low pass filter (LPF), a clock generator and a voltage booster which operate at supply voltage (Vdd) of 0.6V. The designed IA achieves 30dB of closed-loop gain, 101dB of common-mode rejection ratio (CMRR) at 50Hz, 80dB of power-supply rejection ratio (PSRR) at 50Hz, thermal noise floor of 53.4 nV/√Hz, current consumption of 14µA, and noise efficiency factor (NEF) of 9.7. The high CMRR and rail-to-rail output swing capability is attributed to a new low voltage realization of the active-bootstrapped technique using a pseudo-differential gain-boosting operational transconductance amplifier (OTA) and proposed current-driven bulk (CDB) biasing technique. An output capacitor-less low-dropout regulator (LDO), with a new fast start-up LPF technique, is used to regulate this 0.6V supply from a 0.8-1.0V energy harvesting power source. It achieves power supply rejection (PSR) of 42dB at frequency of 1MHz. A cascode compensated pseudo differential amplifier is used as the filter's building block for low power design. The filter's single-ended-to-balanced converter is implemented using a new low voltage amplifier with two-stage common-mode cancellation. The overall AFE was simulated to have 65.6dB of signal-to-noise ratio (SNR), total harmonic distortion (THD) of less than 0.9% for a 100Hz sinusoidal maximum input signal, bandwidth of 2kHz, and power consumption of 51.2µW. Spectre RF simulations were performed to validate the design using BSIM3V3 transistor models provided by GLOBALFOUNDRIES 0.18µm CMOS process.

HIGH RESOLUTION ANALOG / DIGITAL POWER SUPPLY CONTROLLER

International Nuclear Information System (INIS)

Medvedko, Evgeny A

2003-01-01

Corrector magnets for the SPEAR-3 synchrotron radiation source require precision, high-speed control for use with beam-based orbit feedback. A new Controller Analog/Digital Interface card (CANDI) has been developed for these purposes. The CANDI has a 24-bit DAC for current control and three 24-bit Δ-Σ ADCs to monitor current and voltages. The ADCs can be read and the DAC updated at the 4 kHz rate needed for feedback control. A precision 16-bit DAC provides on-board calibration. Programmable multiplexers control internal signal routing for calibration, testing, and measurement. Feedback can be closed internally on current setpoint, externally on supply current, or beam position. Prototype and production tests are reported in this paper. Noise is better than 17 effective bits in a 10 mHz to 2 kHz bandwidth. Linearity and temperature stability are excellent

PC-based control of a high-voltage injector

International Nuclear Information System (INIS)

Constantin, F.

1998-01-01

current control was realized by a stepping motor that rotates a variable resistor through an insulating stick. Two hundred motor steps per complete rotation assumes a very good resolution in driving the filament current between 0 Amps and maximum 40 Amps. The gas flow control is realized by a stepping motor that drives a needle valve. The flow gas can be varied in very small steps. The vacuum read-out is performed by two gauges, Penning and Pirani, providing a 0 to 10 V analog signal. The DC voltages are input to two ADC channels. The current and voltage source control is performed by ADC and DAC channels that drive/read the source output. The outside computer presents an user friendly interface by a Visual Basic program. It permits to vary all the mentioned quantities and reports periodically (at every two seconds) the output values. The user drives the program only with the mouse, having complete control all over the electric hardware inside the injector. A fast reset function is also provided in case of severe malfunction. (author)

A Novel Sliding Mode Control Technique for Indirect Current Controlled Active Power Filter

Directory of Open Access Journals (Sweden)

Juntao Fei

2012-01-01

Full Text Available A novel sliding mode control (SMC method for indirect current controlled three-phase parallel active power filter is presented in this paper. There are two designed closed loops in the system: one is the DC voltage controlling loop and the other is the reference current tracking loop. The first loop with a PI regulator is used to control the DC voltage approximating to the given voltage of capacitor, and the output of PI regulator through a low-pass filter is applied as the input of the power supply reference currents. The second loop implements the tracking of the reference currents using integral sliding mode controller, which can improve the harmonic treating performance. Compared with the direct current control technique, it is convenient to be implemented with digital signal processing system because of simpler system structure and better harmonic treating property. Simulation results verify that the generated reference currents have the same amplitude with the load currents, demonstrating the superior harmonic compensating effects with the proposed shunt active power filter compared with the hysteresis method.

Improvement of burst-mode control of piezoelectric transformer based DC/DC converter

International Nuclear Information System (INIS)

Vasic, Dejan; Liu, Yuan-Ping; Costa, François; Schwander, Denis; Wu, Wen-Jong

2013-01-01

Burst-mode operation is adopted sometimes in piezoelectric transformer based converters for two major purposes: (1) to achieve voltage regulation in DC/DC converters and (2) to achieve dimming control in backlight inverters. Burst-mode control enables the converter to operate at a constant switching frequency as well as to maintain good efficiency at light load conditions. However, in practice, the piezoelectric transformer cannot instantly stop vibrating in the burst-mode due to its high quality factor. The delay in the output voltage change resulting from this behavior influences the accuracy of the regulation. This paper proposes a control strategy to make the piezoelectric transformer stop more quickly so as to enhance the accuracy of burst-mode control. The proposed method only modifies the control signal of the burst-mode driving circuit. The proposed control strategy is verified by experiments in a step-down 9 W DC/DC converter. (paper)

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

African Journals Online (AJOL)

In this paper, the performance study of a separately excited d. c. motor whose speed is controlled by armature voltage variation is presented. Both the open loop and the closed loop steady state and transient characteristics are reported. The speed controllers considered in the closed loop mode are the proportional and the ...

Shaping the spectra of the line-to-line voltage using signal injection in the common mode voltage

DEFF Research Database (Denmark)

Mathe, Laszlo; Rasmussen, Peter Omand; Pedersen, John Kim

2009-01-01

A drawback of Pulse Width Modulation in electrical drives is the high harmonic content of the line to line voltages, which gives rise to Electro-Magnetic Interference and acoustic noise. By injection of a signal into the common mode voltage, the fundamental is not affected, but new frequency...

Autonomous Control Strategy of DC Microgrid for Islanding Mode Using Power Line Communication

Directory of Open Access Journals (Sweden)

Dong-Keun Jeong

2018-04-01

Full Text Available This paper proposes a DC-bus signaling (DBS method for autonomous power management in a DC microgrid, used to improve its reliability. Centralized power management systems require communication between the power sources and loads. However, the DBS method operates based on the common DC-bus voltage and does not require communication. Based on the DC-bus voltage band, the DC-bus voltage can be used to inform the status of the DC-bus in various scenarios. The DC microgrid operates independently to maintain the system stably in the DC-bus voltage band. The DC microgrid can be divided into a grid-connected mode and an islanding mode. This paper proposes a control strategy based on power management of various independent components in islanding mode. In addition, the autonomous control method for switching the converter’s operation between grid-connected mode and islanding mode is proposed. A DC microgrid test bed consisting of a grid-connected AC/DC converter, a bidirectional DC/DC converter, a renewable energy simulator, DC home appliances and a DC-bus protector is used to test the proposed control strategy. The proposed autonomous control strategy is experimentally verified using the DC microgrid test bed.

A current-mode voltage regulator with an embedded sub-threshold reference for a passive UHF RFID transponder

Energy Technology Data Exchange (ETDEWEB)

Liu Zhongqi [Department of Electronic Engineering, Tsinghua University, Beijing 100084 (China); Zhang Chun; Li Yongming; Wang Zhihua, E-mail: liu-zq04@mails.tsinghua.edu.c [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

2010-06-15

This paper presents a current-mode voltage regulator for a passive UHF RFID transponder. The passive tag power is extracted from RF energy through the RF-to-DC rectifier. Due to huge variations of the incoming RF power, the rectifier output voltage should be regulated to achieve a stable power supply. By accurately controlling the current flowing into the load with an embedded sub-threshold reference, the regulated voltage varies in a range of 1-1.3 V from -20 to 80 {sup 0}C, and a bandwidth of about 100 kHz is achieved for a fast power recovery. The circuit is fabricated in UMC 0.18 {mu}m mixed-mode CMOS technology, and the current consumption is only 1 {mu}A. (semiconductor integrated circuits)

A current-mode voltage regulator with an embedded sub-threshold reference for a passive UHF RFID transponder

International Nuclear Information System (INIS)

Liu Zhongqi; Zhang Chun; Li Yongming; Wang Zhihua

2010-01-01

This paper presents a current-mode voltage regulator for a passive UHF RFID transponder. The passive tag power is extracted from RF energy through the RF-to-DC rectifier. Due to huge variations of the incoming RF power, the rectifier output voltage should be regulated to achieve a stable power supply. By accurately controlling the current flowing into the load with an embedded sub-threshold reference, the regulated voltage varies in a range of 1-1.3 V from -20 to 80 0 C, and a bandwidth of about 100 kHz is achieved for a fast power recovery. The circuit is fabricated in UMC 0.18 μm mixed-mode CMOS technology, and the current consumption is only 1 μA. (semiconductor integrated circuits)

A novel high voltage start up circuit for an integrated switched mode power supply

Energy Technology Data Exchange (ETDEWEB)

Hu Hao; Chen Xingbi, E-mail: huhao21@uestc.edu.c [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2010-09-15

A novel high voltage start up circuit for providing an initial bias voltage to an integrated switched mode power supply (SMPS) is presented. An enhanced mode VDMOS transistor, the gate of which is biased by a floating p-island, is used to provide start up current and sustain high voltage. An NMOS transistor having a high source to ground breakdown voltage is included to extend the bias voltage range to the SMPS. Simulation results indicate that the high voltage start up circuit can start and restart as designed. The proposed structure is believed to be more energy saving and cost-effective compared with other solutions. (semiconductor devices)

Voltage-controlled Enzymes: The new Janus Bifrons

Directory of Open Access Journals (Sweden)

Carlos Alberto Villalba-Galea

2012-09-01

Full Text Available The Ciona intestinalis voltage sensitive phosphatase, Ci-VSP, was the first Voltage-controlled Enzyme (VEnz proven to be under direct command of the membrane potential. The discovery of Ci-VSP conjugated voltage sensitivity and enzymatic activity in a single protein. These two facets of Ci-VSP activity have provided a unique model for studying how membrane potential is sensed by proteins and a novel mechanism for control of enzymatic activity. These facets make Ci-VSP a fascinating and versatile enzyme.Ci-VSP has a voltage sensing domain (VSD that resembles those found in voltage-gated channels (VGC. The VSD resides in the N-terminus and is formed by four putative trans-membrane segments. The fourth segment contains charged residues which are likely involved in voltage sensing. Ci-VSP produces sensing currents in response to changes in potential, within a defined range of voltages. Sensing currents are analogous to gating currents in VGC. As known, these latter proteins contain four VSDs which are entangled in a complex interaction with the pore domain –the effector domain in VGC. This complexity makes studying the basis of voltage sensing in VGC a difficult enterprise. In contrast, Ci-VSP is thought to be monomeric and its catalytic domain –the VSP’s effector domain– can be cleaved off without disrupting the basic electrical functioning of the VSD. For these reasons, VSPs are considered a great model for studying the activity of a VSD in isolation. Finally, VSPs are also phosphoinositide phosphatases. Phosphoinositides are signaling lipids found in eukaryotes and are involved in many processes, including modulation of VGC activity and regulation of cell proliferation. Understanding VSPs as VEnz has been the center of attention in recent years and several reviews has been dedicated to this area. Thus, this review will be focused instead on the other face of this true Janus Bifrons and recapitulate what is known about VSPs as electrically

Scalability of voltage-controlled filamentary and nanometallic resistance memory devices.

Science.gov (United States)

Lu, Yang; Lee, Jong Ho; Chen, I-Wei

2017-08-31

Much effort has been devoted to device and materials engineering to realize nanoscale resistance random access memory (RRAM) for practical applications, but a rational physical basis to be relied on to design scalable devices spanning many length scales is still lacking. In particular, there is no clear criterion for switching control in those RRAM devices in which resistance changes are limited to localized nanoscale filaments that experience concentrated heat, electric current and field. Here, we demonstrate voltage-controlled resistance switching, always at a constant characteristic critical voltage, for macro and nanodevices in both filamentary RRAM and nanometallic RRAM, and the latter switches uniformly and does not require a forming process. As a result, area-scalability can be achieved under a device-area-proportional current compliance for the low resistance state of the filamentary RRAM, and for both the low and high resistance states of the nanometallic RRAM. This finding will help design area-scalable RRAM at the nanoscale. It also establishes an analogy between RRAM and synapses, in which signal transmission is also voltage-controlled.

Digitally Programmable High-Q Voltage Mode Universal Filter

Directory of Open Access Journals (Sweden)

D. Singh

2013-12-01

Full Text Available A new low-voltage low-power CMOS current feedback amplifier (CFA is presented in this paper. This is used to realize a novel digitally programmable CFA (DPCFA using transistor arrays and MOS switches. The proposed realizations nearly allow rail-to-rail swing capability at all the ports. Class-AB output stage ensures low power dissipation and high current drive capability. The proposed CFA/ DPCFA operates at supply voltage of ±0.75 V and exhibits bandwidth better than 95 MHz. An application of the DPCFA to realize a novel voltage mode high-Q digitally programmable universal filter (UF is given. Performances of all the proposed circuits are verified by PSPICE simulation using TSMC 0.25μm technology parameters.

Impacts of Voltage Control Methods on Distribution Circuit’s Photovoltaic (PV Integration Limits

Directory of Open Access Journals (Sweden)

Anamika Dubey

2017-10-01

Full Text Available The widespread integration of photovoltaic (PV units may result in a number of operational issues for the utility distribution system. The advances in smart-grid technologies with better communication and control capabilities may help to mitigate these challenges. The objective of this paper is to evaluate multiple voltage control methods and compare their effectiveness in mitigating the impacts of high levels of PV penetrations on distribution system voltages. A Monte Carlo based stochastic analysis framework is used to evaluate the impacts of PV integration, with and without voltage control. Both snapshot power flow and time-series analysis are conducted for the feeder with varying levels of PV penetrations. The methods are compared for their impacts on (1 the feeder’s PV hosting capacity; (2 the number of voltage violations and the magnitude of the largest bus voltage; (3 the net reactive power demand from the substation; and (4 the number of switching operations of feeder’s legacy voltage support devices i.e., capacitor banks and load tap changers (LTCs. The simulation results show that voltage control help in mitigating overvoltage concerns and increasing the feeder’s hosting capacity. Although, the legacy control solves the voltage concerns for primary feeders, a smart inverter control is required to mitigate both primary and secondary feeder voltage regulation issues. The smart inverter control, however, increases the feeder’s reactive power demand and the number of LTC and capacitor switching operations. For the 34.5-kV test circuit, it is observed that the reactive power demand increases from 0 to 6.8 MVAR on enabling Volt-VAR control for PV inverters. The total number of capacitor and LTC operations over a 1-year period also increases from 455 operations to 1991 operations with Volt-VAR control mode. It is also demonstrated that by simply changing the control mode of capacitor banks, a significant reduction in the unnecessary

Comment on “Voltage-Mode All-Pass Filters Including Minimum Component Count Circuits”

OpenAIRE

Lahiri, Abhirup

2009-01-01

This comment is related to the recently published article “Active and Passive Electronic Components” by S. Maheshwari (2007), which presents single current differencing buffered amplifier (CDBA) and current-controlled current differencing buffered amplifier- (CC-CDBA-) based first-order voltage-mode (VM) all-pass filtering (APF) sections. The paper is reviewed, and additional first-order APF realizations have been proposed.

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.

Low Voltage Current Mode Switched-Current-Mirror Mixer

Directory of Open Access Journals (Sweden)

Chunhua Wang

2009-09-01

Full Text Available A new CMOS active mixer topology can operate at 1 V supply voltage by use of SCM (switched currentmirror. Such current-mode mixer requires less voltage headroom with good linearization. Mixing is achieved with four improved current mirrors, which are alternatively activated. For ideal switching, the operation is equivalent to a conventional active mixer. This paper analyzes the performance of the SCM mixer, in comparison with the conventional mixer, demonstrating competitive performance at a lower supply voltage. Moreover, the new mixer’s die, without any passive components, is very small, and the conversion gain is easy to adjust. An experimental prototype was designed and simulated in standard chartered 0.18μm RF CMOS Process with Spectre in Cadence Design Systems. Experimental results show satisfactory mixer performance at 2.4 GHz.

Monolithic quasi-sliding-mode controller for SIDO buck converter with a self-adaptive free-wheeling current level

Science.gov (United States)

Xiaobo, Wu; Qing, Liu; Menglian, Zhao; Mingyang, Chen

2013-01-01

An analog implementation of a novel fixed-frequency quasi-sliding-mode controller for single-inductor dual-output (SIDO) buck converter in pseudo-continuous conduction mode (PCCM) with a self-adaptive freewheeling current level (SFCL) is presented. Both small and large signal variations around the operation point are considered to achieve better transient response so as to reduce the cross-regulation of this SIDO buck converter. Moreover, an internal integral loop is added to suppress the steady-state regulation error introduced by conventional PWM-based sliding mode controllers. Instead of keeping it as a constant value, the free-wheeling current level varies according to the load condition to maintain high power efficiency and less cross-regulation at the same time. To verify the feasibility of the proposed controller, an SIDO buck converter with two regulated output voltages, 1.8 V and 3.3 V, is designed and fabricated in HEJIAN 0.35 μm CMOS process. Simulation and experiment results show that the transient time of this SIDO buck converter drops to 10 μs while the cross-regulation is reduced to 0.057 mV/mA, when its first load changes from 50 to 100 mA.

Voltage control on a train system

Science.gov (United States)

Gordon, Susanna P.; Evans, John A.

2004-01-20

The present invention provides methods for preventing low train voltages and managing interference, thereby improving the efficiency, reliability, and passenger comfort associated with commuter trains. An algorithm implementing neural network technology is used to predict low voltages before they occur. Once voltages are predicted, then multiple trains can be controlled to prevent low voltage events. Further, algorithms for managing inference are presented in the present invention. Different types of interference problems are addressed in the present invention such as "Interference During Acceleration", "Interference Near Station Stops", and "Interference During Delay Recovery." Managing such interference avoids unnecessary brake/acceleration cycles during acceleration, immediately before station stops, and after substantial delays. Algorithms are demonstrated to avoid oscillatory brake/acceleration cycles due to interference and to smooth the trajectories of closely following trains. This is achieved by maintaining sufficient following distances to avoid unnecessary braking/accelerating. These methods generate smooth train trajectories, making for a more comfortable ride, and improve train motor reliability by avoiding unnecessary mode-changes between propulsion and braking. These algorithms can also have a favorable impact on traction power system requirements and energy consumption.

Efficiency and hardware comparison of analog control-based and digital control-based 70 W two-stage power factor corrector and DC-DC converters

DEFF Research Database (Denmark)

Török, Lajos; Munk-Nielsen, Stig

2011-01-01

A comparison of an analog and a digital controller driven 70 W two-stage power factor corrector converter is presented. Both controllers are operated in average current-mode-control for the PFC and peak current control for the DC-DC converter. Digital controller design and converter modeling...... is described. Results show that digital control can compete with the analog one in efficiency, PFC and THD....

Common-mode Voltage Reduction in a Motor Drive System with a Power Factor Correction

DEFF Research Database (Denmark)

Adabi, J.; Boora, A.A.; Zare, F.

2012-01-01

Common-mode voltage generated by a power converter in combination with parasitic capacitive couplings is a potential source of shaft voltage in an AC motor drive system. In this study, a three-phase motor drive system supplied with a single-phase AC-DC diode rectifier is investigated in order...... to reduce shaft voltage in a three-phase AC motor drive system. In this topology, the AC-DC diode rectifier influences the common-mode voltage generated by the inverter because the placement of the neutral point is changing in different rectifier circuit states. A pulse width modulation technique...

Surface acoustic waves voltage controlled directional coupler

Science.gov (United States)

Golan, G.; Griffel, G.; Yanilov, E.; Ruschin, S.; Seidman, A.; Croitoru, N.

1988-10-01

An important condition for the development of surface wave integrated-acoustic devices is the ability to guide and control the propagation of the acoustic energy. This can be implemented by deposition of metallic "loading" channels on an anisotropic piezoelectric substrate. Deposition of such two parallel channels causes an effective coupling of acoustic energy from one channel to the other. A basic requirement for this coupling effect is the existence of the two basic modes: a symmetrical and a nonsymmetrical one. A mode map that shows the number of sustained modes as a function of the device parameters (i.e., channel width; distance between channels; material velocity; and acoustical exciting frequency) is presented. This kind of map can help significantly in the design process of such a device. In this paper we devise an advanced acoustical "Y" coupler with the ability to control its effective coupling by an externally applied voltage, thereby causing modulation of the output intensities of the signals.

Model Predictive Voltage Control of Wind Power Plants

DEFF Research Database (Denmark)

Zhao, Haoran; Wu, Qiuwei

2018-01-01

the efficacy of the proposed WFVC, two case scenarios were designed: the wind farm is under normal operating conditions and the internal wind power fluctuation is considered; and besides internal power fluctuation, the impact of the external grid on the wind farm is considered.......This chapter proposes an autonomous wind farm voltage controller (WFVC) based on model predictive control (MPC). It also introduces the analytical expressions for the voltage sensitivity to tap positions of a transformer. The chapter then describes the discrete models for the wind turbine...... generators (WTGs) and static var compensators (SVCs)/static var generators (SVGs). Next, it describes the implementation of the on‐load tap changing (OLTC) in the MPC. Furthermore, the chapter examines the cost function as well as the constraints of the MPC‐based WFVC for both control modes. In order to test...

Determining the mode of high voltage breakdowns in vacuum devices

International Nuclear Information System (INIS)

Miller, H.C.; Furno, E.J.; Sturtz, J.P.

1980-01-01

High voltage breakdowns (HVBs) occur in many vacuum devices. It frequently is of great practical interest to know the type (or mode) of such HVB's, since this can indicate weak points in the device. Post-mortems can sometimes be helpful, but it would be quite desirable to have a technique which would allow the HVB mode to be determined in an operating device. Photography can be quite helpful, but unfortunately many devices do not permit optical access to the region of interest. However, the idea of using photography in conjunction with other diagnostic techniques to establish the validity of these techniques seemed promising, since these techniques could then be used to determine the mode of HVBs in opaque devices. A literature search indicates that promising techniques are to measure the voltage applied to the device (or the current through the device) and also to look for x-rays generated by the device during an HVB

Mitigation of Voltage and Current Harmonics in Grid-Connected Microgrids

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Guerrero, Josep M.; Jalilian, Alireza

2012-01-01

In this paper, a control approach is proposed for selective compensation of main voltage and current harmonics in grid-connected microgrids. Two modes of compensation are considered, i.e. voltage and current compensation modes. In the case that sensitive loads are connected to the point of common...... coupling (PCC), voltage compensation mode is activated in order to provide a high voltage quality at PCC. Otherwise, grid current harmonics are mitigated (current compensation mode) in order to avoid excessive harmonic supply by the grid. In both modes, harmonic compensation is achieved through proper...... control of distributed generators (DGs) interface converters. The compensation effort of each harmonic is shared considering the corresponding current harmonic supplied by the DGs. The control system of each DG comprises harmonic compensator, power controllers, voltage and current controllers and virtual...

Sliding-Mode Control to Compensate PVT Variations in Dual Core Systems

NARCIS (Netherlands)

Pourshaghaghi, H.R.; Fatemi, S.H.; Pineda de Gyvez, J.

2012-01-01

In this paper, we present a novel robust sliding-mode controller for stabilizing supply voltage and clock frequency of dual core processors determined by dynamic voltage and frequency scaling (DVFS) methods in the presence of systematic and random variations. We show that maximum rejection for

Research on Integrated Control of Microgrid Operation Mode

Science.gov (United States)

Cheng, ZhiPing; Gao, JinFeng; Li, HangYu

2018-03-01

The mode switching control of microgrid is the focus of its system control. According to the characteristics of different control, an integrated control system is put forward according to the detecting voltage and frequency deviation after switching of microgrid operating mode. This control system employs master-slave and peer-to-peer control. Wind turbine and photovoltaic(PV) adopt P/Q control, so the maximum power output can be achieved. The energy storage will work under the droop control if the system is grid-connected. When the system is off-grid, whether to employ droop control or P/f control is determined by system status. The simulation has been done and the system performance can meet the requirement.

All-Pass Filter Based Linear Voltage Controlled Quadrature Oscillator

Directory of Open Access Journals (Sweden)

Koushick Mathur

2017-01-01

Full Text Available A linear voltage controlled quadrature oscillator implemented from a first-order electronically tunable all-pass filter (ETAF is presented. The active element is commercially available current feedback amplifier (AD844 in conjunction with the relatively new Multiplication Mode Current Conveyor (MMCC device. Electronic tunability is obtained by the control node voltage (V of the MMCC. Effects of the device nonidealities, namely, the parasitic capacitors and the roll-off poles of the port-transfer ratios of the device, are shown to be negligible, even though the usable high-frequency ranges are constrained by these imperfections. Subsequently the filter is looped with an electronically tunable integrator (ETI to implement the quadrature oscillator (QO. Experimental responses on the voltage tunable phase of the filter and the linear-tuning law of the quadrature oscillator up to 9.9 MHz at low THD are verified by simulation and hardware tests.

MOSFET analog memory circuit achieves long duration signal storage

Science.gov (United States)

1966-01-01

Memory circuit maintains the signal voltage at the output of an analog signal amplifier when the input signal is interrupted or removed. The circuit uses MOSFET /Metal Oxide Semiconductor Field Effect Transistor/ devices as voltage-controlled switches, triggered by an external voltage-sensing device.

Coordinated Voltage Control of Distributed PV Inverters for Voltage Regulation in Low Voltage Distribution Networks

DEFF Research Database (Denmark)

Nainar, Karthikeyan; Pokhrel, Basanta Raj; Pillai, Jayakrishnan Radhakrishna

2017-01-01

This paper reviews and analyzes the existing voltage control methods of distributed solar PV inverters to improve the voltage regulation and thereby the hosting capacity of a low-voltage distribution network. A novel coordinated voltage control method is proposed based on voltage sensitivity...... optimization. The proposed method is used to calculate the voltage bands and droop settings of PV inverters at each node by the supervisory controller. The local controller of each PV inverter implements the volt/var control and if necessary, the active power curtailment as per the received settings and based...... on measured local voltages. The advantage of the proposed method is that the calculated reactive power and active power droop settings enable fair contribution of the PV inverters at each node to the voltage regulation. Simulation studies are conducted using DigSilent Power factory software on a simplified...

Analog filters in nanometer CMOS

CERN Document Server

Uhrmann, Heimo; Zimmermann, Horst

2014-01-01

Starting from the basics of analog filters and the poor transistor characteristics in nanometer CMOS 10 high-performance analog filters developed by the authors in 120 nm and 65 nm CMOS are described extensively. Among them are gm-C filters, current-mode filters, and active filters for system-on-chip realization for Bluetooth, WCDMA, UWB, DVB-H, and LTE applications. For the active filters several operational amplifier designs are described. The book, furthermore, contains a review of the newest state of research on low-voltage low-power analog filters. To cover the topic of the book comprehensively, linearization issues and measurement methods for the characterization of advanced analog filters are introduced in addition. Numerous elaborate illustrations promote an easy comprehension. This book will be of value to engineers and researchers in industry as well as scientists and Ph.D students at universities. The book is also recommendable to graduate students specializing on nanoelectronics, microelectronics ...

Potentially damaging failure modes of high- and medium-voltage electrical equipment

International Nuclear Information System (INIS)

Hoy, H.C.

1984-01-01

The high- and medium-voltage electrical equipment failures of both nuclear and nonnuclear electric utilities have been reviewed for possible disruptive failure modes that would be of special concern in a nuclear power plant. The resulting emphasis was on the electrical faults of transformers, switchgear (circuit breakers), lightning (surge) arrestors, high-voltage cabling and buswork, control boards, and other electrical equipment that, through failure, can be the initiating event that may expand the original fault to nearby or associated equipment. Many failures of such equipment were found and documented, although the failure rate of electrical equipment in utilities is historically quite low. Nuclear plants record too few failures to be statistically valid, but failures that have been recorded show that good design usually restricts the failure to a single piece of equipment. Conclusions and recommendations pertaining to the design, maintenance, and operation of the affected electrical equipment are presented

Voltage-Mode Four-Phase Sinusoidal Generator and Its Useful Extensions

Directory of Open Access Journals (Sweden)

Sudhanshu Maheshwari

2013-01-01

Full Text Available This paper introduces a new voltage-mode second-order sinusoidal generator circuit with four active elements and six passive elements, including grounded capacitors. The frequency and condition of oscillation can be independently controlled. The effect of active element’s nonidealities and parasitic effects is also studied; the proposed topology is good in absorbing several parasitic elements involved with the active elements. The circuit is advantageous for generating high frequency signals which is demonstrated for 25 MHz outputs. Several circuit extensions are also given which makes the new proposal useful for real circuit adoption. The proposed theory is validated through simulation results.

A Unified Voltage Harmonic Control Strategy for Coordinated Compensation with VCM and CCM Converters

DEFF Research Database (Denmark)

Zhao, Xin; Meng, Lexuan; Xie, Chuan

2018-01-01

-controlled mode (VCM) and current-controlled mode (CCM), need to cooperatively provide the compensation function. Aiming at this objective, this paper proposes a unified voltage harmonic mitigation strategy for VCM and CCM converters with high harmonic current sharing accuracy. Another advantage of the proposal......Harmonics have been considered as one of the major issues in modern power grids. Considering the high penetration level of power electronic converter interfaced distributed generators (DGs), it is of interest to provide ancillary services through DG interfacing converters, such as harmonic...... compensation. In case of that, multiple DG interfacing converters are utilized to compensate harmonics, and the compensation effort should be properly shared among these converters. However, it is rarely considered in existing literatures that converters operating in different modes, such as voltage...

Analog Fixed Maximum Power Point Control for a PWM Step-downConverter for Water Pumping Installations

DEFF Research Database (Denmark)

Beltran, H.; Perez, E.; Chen, Zhe

2009-01-01

This paper describes a Fixed Maximum Power Point analog control used in a step-down Pulse Width Modulated power converter. The DC/DC converter drives a DC motor used in small water pumping installations, without any electric storage device. The power supply is provided by PV panels working around....... The proposed Optimal Power Point fix voltage control system is analyzed in comparison to other complex controls....... their maximum power point, with a fixed operating voltage value. The control circuit implementation is not only simple and cheap, but also robust and reliable. System protections and adjustments are also proposed. Simulations and hardware are reported in the paper for a 150W water pumping application system...

Monolithic quasi-sliding-mode controller for SIDO buck converter with a self-adaptive free-wheeling current level

International Nuclear Information System (INIS)

Wu Xiaobo; Liu Qing; Zhao Menglian; Chen Mingyang

2013-01-01

An analog implementation of a novel fixed-frequency quasi-sliding-mode controller for single-inductor dual-output (SIDO) buck converter in pseudo-continuous conduction mode (PCCM) with a self-adaptive freewheeling current level (SFCL) is presented. Both small and large signal variations around the operation point are considered to achieve better transient response so as to reduce the cross-regulation of this SIDO buck converter. Moreover, an internal integral loop is added to suppress the steady-state regulation error introduced by conventional PWM-based sliding mode controllers. Instead of keeping it as a constant value, the free-wheeling current level varies according to the load condition to maintain high power efficiency and less cross-regulation at the same time. To verify the feasibility of the proposed controller, an SIDO buck converter with two regulated output voltages, 1.8 V and 3.3 V, is designed and fabricated in HEJIAN 0.35 μm CMOS process. Simulation and experiment results show that the transient time of this SIDO buck converter drops to 10 μs while the cross-regulation is reduced to 0.057 mV/mA, when its first load changes from 50 to 100 mA. (semiconductor integrated circuits)

Modeling, analysis, and design of stationary reference frame droop controlled parallel three-phase voltage source inverters

DEFF Research Database (Denmark)

Vasquez, Juan Carlos; Guerrero, Josep M.; Savaghebi, Mehdi

2011-01-01

and discussed. Experimental results are provided to validate the performance and robustness of the VSIs functionality during Islanded and grid-connected operations, allowing a seamless transition between these modes through control hierarchies by regulating frequency and voltage, main-grid interactivity......Power electronics based microgrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of three-phase VSIs are derived. The proposed voltage and current inner control loops and the mathematical models...

Electronically Tunable Current Controlled Current Conveyor Transconductance Amplifier-Based Mixed-Mode Biquadratic Filter with Resistorless and Grounded Capacitors

Directory of Open Access Journals (Sweden)

Hua-Pin Chen

2017-03-01

Full Text Available A new electronically tunable mixed-mode biquadratic filter with three current controlled current conveyor transconductance amplifiers (CCCCTAs and two grounded capacitors is proposed. With current input, the filter can realise lowpass (LP, bandpass (BP, highpass (HP, bandstop (BS and allpass (AP responses in current mode and LP, BP and HP responses in transimpedance mode. With voltage input, the filter can realise LP, BP, HP, BS and AP responses in voltage and transadmittance modes. Other attractive features of the mixed-mode biquadratic filter are (1 the use of two grounded capacitors, which is ideal for integrated circuit implementation; (2 orthogonal control of the quality factor (Q and resonance angular frequency (ωo for easy electronic tenability; (3 low input impedance and high output impedance for current signals; (4 high input impedance for voltage signal; (5 avoidance of need for component-matching conditions; (6 resistorless and electronically tunable structure; (7 low active and passive sensitivities; and (8 independent control of the voltage transfer gains without affecting the parameters ωo and Q.

Modelling of V-Hz and vector controlled ASDs in PSCAD/EMTDC for voltage sag studies

Energy Technology Data Exchange (ETDEWEB)

Vegunta, S.C. [TNEI Services Ltd, Manchester M1 2PW (United Kingdom); Milanovic, J.V. [School of Electrical and Electronic Engineering of The University of Manchester, PO Box 88, Manchester M60 1QD (United Kingdom); Djokic, S.Z. [School of Engineering of The University of Edinburgh, The King' s Buildings, Mayfield Road, Edinburgh EH9 3JL (United Kingdom)

2010-01-15

This paper deals with modelling and performance of adjustable speed drives (ASDs) subjected to voltage disturbances in electric supply. The aim of this study was to develop appropriate models of typical ASD and investigate their sensitivity to voltage disturbances under various practical modes of operation and control. Accordingly, scalar controlled open and closed loop volts-hertz (V-Hz) and vector controlled closed loop ASDs are modelled in PSCAD/EMTDC environment, and their performance in the presence of voltage disturbances is investigated under typical operating and loading conditions. The drive sensitivity to three-phase, two-phase and single-phase voltage sags and short interruptions was assessed, and the findings are discussed in the paper. Depending on the type of drive control, type of voltage sag, applied load torque and adjusted speed, various sensitivity curves were established and analyzed. (author)

Digital control of high-frequency switched-mode power converters

CERN Document Server

Corradini, Luca; Mattavelli, Paolo; Zane, Regan

This book is focused on the fundamental aspects of analysis, modeling and design of digital control loops around high-frequency switched-mode power converters in a systematic and rigorous manner Comprehensive treatment of digital control theory for power converters Verilog and VHDL sample codes are provided Enables readers to successfully analyze, model, design, and implement voltage, current, or multi-loop digital feedback loops around switched-mode power converters Practical examples are used throughout the book to illustrate applications of the techniques developed Matlab examples are also

Cooperative Control with Virtual Selective Harmonic Capacitance for Harmonic Voltage Compensation in Islanded MicroGrids

DEFF Research Database (Denmark)

Micallef, A.; Apap, M.; Spitero-Stanies, C.

2012-01-01

This paper focuses on the islanded operation of microgrids. In this mode of operation, the microsources are required to cooperate autonomously to regulate the local grid voltage and frequency. Droop control is typically used to achieve this autonomous voltage and frequency regulation. Inverters...... having LCL output filters would cause voltage distortion to be present at the PCC of the local load when non-linear current is supplied to the load due to the voltage drop across the grid side inductor. Techniques to reduce the output voltage distortion typically consist of installing either passive...

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.

Influence of Wind Plant Ancillary Voltage Control on System Small Signal Stability

DEFF Research Database (Denmark)

Su, Chi; Chen, Zhe

2012-01-01

As a common tendency, large-scale wind farms are increasingly connected to the transmission system of modern power grids. This introduces some new challenges to the connected power systems, and the transmission system operators (TSOs) have to put some new requirements as part of the grid codes...... on the integration of wind farms. One common requirement to wind farms is the function of system voltage control which can be implemented in the grid-side convertor controller of a variable speed wind turbine. This ancillary voltage control provided by wind farms could have some influence on the system small signal...... stability. This paper implements an ancillary voltage control strategy on a direct-drive-full-convertor-based wind farm and studies its influence on the damping ratio values of the dominant oscillation mode within the connected power system. All the calculations and simulations are conducted in DIg...

Sensorless sliding mode torque control of an IPMSM drive based on active flux concept

Directory of Open Access Journals (Sweden)

A.A. Hassan

2012-03-01

Full Text Available This paper investigates a novel direct torque control of a sensorless interior permanent magnet synchronous motor based on a sliding mode technique. The speed and position of the interior permanent magnet synchronous motor are estimated online based on active flux concept. To overcome the large ripple content associated with the direct torque, a torque/flux sliding mode controller has been employed. Two integral surface functions are used to construct the sliding mode controller. The command voltage is estimated from the torque and flux errors based on the two switching functions. The idea of the total sliding mode is used to eliminate the problem of reaching phase stability. The space vector modulation is combined with the sliding mode controller to ensure minimum torque and flux ripples and provides high resolution voltage control. The proposed scheme has the advantages of simple implementation, and does not require an external signal injection. In addition, it combines the merits of the direct torque control, sliding mode controller, and space vector modulation besides to the sensorless control. Simulation works are carried out to demonstrate the ability of the proposed scheme at different operating conditions. The results confirm the high performance of the proposed scheme at standstill, low and high speeds including load disturbance and parameters variation.

Adaptive super-twisting sliding mode control for a three-phase single-stage grid-connected differential boost inverter based photovoltaic system.

Science.gov (United States)

Pati, Akshaya K; Sahoo, N C

2017-07-01

This paper presents an adaptive super-twisting sliding mode control (STC) along with double-loop control for voltage tracking performance of three-phase differential boost inverter and DC-link capacitor voltage regulation in grid-connected PV system. The effectiveness of the proposed control strategies are demonstrated under realistic scenarios such as variations in solar insolation, load power demand, grid voltage, and transition from grid-connected to standalone mode etc. Additional supplementary power quality control functions such as harmonic compensation, and reactive power management are also investigated with the proposed control strategy. The results are compared with conventional proportional-integral controller, and PWM sliding mode controller. The system performance is evaluated in simulation and in real-time. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Harmonic voltage excess problem test and analysis in UHV and EHV grid particular operation mode

Science.gov (United States)

Lv, Zhenhua; Shi, Mingming; Fei, Juntao

2018-02-01

The test and analysis of the power quality of some 1000kV UHV transmission lines and 500kV EHV transmission lines is carried out. It is found that there is harmonic voltage excess problems when the power supply of the UHV and EHV voltage line is single-ended or single-loop, the problem basically disappeared after the operation mode change, different operating conditions, the harmonic current has not been greatly affected, indicating that the harmonic voltage changes mainly caused by the system harmonic impedance. With the analysis of MATLAB Simulink system model, it can be seen that there are specific harmonic voltage excess in the system under the specific operating mode, which results in serious distortion of the specific harmonic voltage. Since such phenomena are found in 500kV and 1000kV systems, it is suggested that the test evaluation work should be done under the typical mode of operation in 500kV, 1000kV Planning and construction process to prevent the occurrence of serious distortion and the regional harmonic current monitoring and suppression work should be done.

High Order Sliding Mode Control of Doubly-fed Induction Generator under Unbalanced Grid Faults

DEFF Research Database (Denmark)

Zhu, Rongwu; Chen, Zhe; Wu, Xiaojie

2013-01-01

This paper deals with a doubly-fed induction generator-based (DFIG) wind turbine system under grid fault conditions such as: unbalanced grid voltage, three-phase grid fault, using a high order sliding mode control (SMC). A second order sliding mode controller, which is robust with respect...

Modern analog filter analysis and design a practical approach

CERN Document Server

Raut, R

2011-01-01

Starting from the fundamentals, the present book describes methods of designing analog electronic filters and illustrates these methods by providing numerical and circuit simulation programs. The subject matters comprise many concepts and techniques that are not available in other text books on the market. To name a few - principle of transposition and its application in directly realizing current mode filters from well known voltage mode filters; an insight into the technological aspect of integrated circuit components used to implement an integrated circuit filter; a careful blending of basi

Modeling and control of distributed energy systems during transition between grid connected and standalone modes

Science.gov (United States)

Arafat, Md Nayeem

Distributed generation systems (DGs) have been penetrating into our energy networks with the advancement in the renewable energy sources and energy storage elements. These systems can operate in synchronism with the utility grid referred to as the grid connected (GC) mode of operation, or work independently, referred to as the standalone (SA) mode of operation. There is a need to ensure continuous power flow during transition between GC and SA modes, referred to as the transition mode, in operating DGs. In this dissertation, efficient and effective transition control algorithms are developed for DGs operating either independently or collectively with other units. Three techniques are proposed in this dissertation to manage the proper transition operations. In the first technique, a new control algorithm is proposed for an independent DG which can operate in SA and GC modes. The proposed transition control algorithm ensures low total harmonic distortion (THD) and less voltage fluctuation during mode transitions compared to the other techniques. In the second technique, a transition control is suggested for a collective of DGs operating in a microgrid system architecture to improve the reliability of the system, reduce the cost, and provide better performance. In this technique, one of the DGs in a microgrid system, referred to as a dispatch unit , takes the additional responsibility of mode transitioning to ensure smooth transition and supply/demand balance in the microgrid. In the third technique, an alternative transition technique is proposed through hybridizing the current and droop controllers. The proposed hybrid transition control technique has higher reliability compared to the dispatch unit concept. During the GC mode, the proposed hybrid controller uses current control. During the SA mode, the hybrid controller uses droop control. During the transition mode, both of the controllers participate in formulating the inverter output voltage but with different

Design and Implementation of Digital Current Mode Controller for DC-DC Converters

DEFF Research Database (Denmark)

Taeed, Fazel

to be regulated by a closed-loop controller. The Peak Current Mode Control (PCMC) is one of the most promising control methods for dc-dc converters. It has been known for high bandwidth (speed), and inherent current protection. Increasing the controller bandwidth decreases the output filter size and cost. Analog...

Characteristics of MAO coating obtained on ZK60 Mg alloy under two and three steps voltage-increasing modes in dual electrolyte

Science.gov (United States)

Yang, Jun; Wang, Ze-Xin; Lu, Sheng; Lv, Wei-gang; Jiang, Xi-zhi; Sun, Lei

2017-03-01

The micro-arc oxidation process was conducted on ZK60 Mg alloy under two and three steps voltage-increasing modes by DC pulse electrical source. The effect of each mode on current-time responses during MAO process and the coating characteristic were analysed and discussed systematically. The microstructure, thickness and corrosion resistance of MAO coatings were evaluated by scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), microscope with super-depth of field and electrochemical impedance spectroscopy (EIS). The results indicate that two and three steps voltage-increasing modes can improve weak spark discharges with insufficient breakdown strength in later period during the MAO process. Due to higher value of voltage and voltage increment, the coating with maximum thickness of about 20.20μm formed under two steps voltage-increasing mode shows the best corrosion resistance. In addition, the coating fabricated under three steps voltage-increasing mode shows a smoother coating with better corrosion resistance due to the lower amplitude of voltage-increasing.

On the specification of bus voltages and radial link transfer impedance modes

Energy Technology Data Exchange (ETDEWEB)

El-Sadik, F.M. [Khartoum Univ., Aljamaa, Khartoum (Sudan)

2010-07-01

No algebraic equation has been derived for the steady-state stability limit (SSSL) of radial power system components in terms of their resistive sectional impedance elements and associated scalar node voltage constraints. While many criterion have been developed in the literature for the steady state angle and voltage stability limits of systems with losses, speculation exists about certain advocated metrics for these systems in terms of stability reserve margins as a measure of the risk of blackout and the representation of reactance modes associated with Putman's model for synchronous machines. This paper presented the results of a generalized algebraic statement for the reactance modes under stability conditions in voltage-specified power system components cited in the single machine-infinite bus (SMIB) and the radial power link (RPL) systems. The direct analytical solution to the problem enabled the identification of 2 different constraint relations for the sending (E) and receiving-end voltage regulator (VR) voltages. The paper discussed the general SSSL function plan, conditions for SMIB system reactances, and index results for the voltage stability of radial lines. The results for the R2 influence and influence on radial compensation levels were also presented. Index results for non-operational reactance zones were provided. It was concluded that the algebraic solution in a full representation of system losses would enable identification of additional function discontinuities that might not reveal in a step-by-step numerical algorithm and that may account for the many unresolved transmission system phenomenon associated with SSSL predictions and capacitance compensation schemes. 11 refs., 1 tab., 5 figs., 3 appendices.

Dynamics and stabilization of peak current-mode controlled buck converter with constant current load

International Nuclear Information System (INIS)

Leng Min-Rui; Zhou Guo-Hua; Zhang Kai-Tun; Li Zhen-Hua

2015-01-01

The discrete iterative map model of peak current-mode controlled buck converter with constant current load (CCL), containing the output voltage feedback and ramp compensation, is established in this paper. Based on this model the complex dynamics of this converter is investigated by analyzing bifurcation diagrams and the Lyapunov exponent spectrum. The effects of ramp compensation and output voltage feedback on the stability of the converter are investigated. Experimental results verify the simulation and theoretical analysis. The stability boundary and chaos boundary are obtained under the theoretical conditions of period-doubling bifurcation and border collision. It is found that there are four operation regions in the peak current-mode controlled buck converter with CCL due to period-doubling bifurcation and border-collision bifurcation. Research results indicate that ramp compensation can extend the stable operation range and transfer the operating mode, and output voltage feedback can eventually eliminate the coexisting fast-slow scale instability. (paper)

Z80 based voltage and temperature monitor for the Main Ring control crate: the CC48 card

International Nuclear Information System (INIS)

Seino, K.

1982-06-01

Several years ago, there seemed to be a need to monitor the power supply voltages and temperatures in the three bay racks of the Main Ring service buildings. A few years ago, another engineer seemed to have done a preliminary design using analog voltage comparators. In late 1979, it was proposed to use a microprocessor instead of analog voltage comparators. It was dramatic that all the people at a meeting were excited about the idea and unanimously approved the project. The author can remember some of the reasons why they were so enthusiastic about the idea at the time, i.e., (1) it was new to have microprocessor based cards on the Main Ring control system, (2) programmable alarm limits were preferred to resistor dividers or potentiometers with analog voltage comparators, (3) it was the first to try the communication between a host computer and distributed intelligent cards. The author started the design on the CC48 in January, 1980 and completed in April, 1980. We had the prototype card working in July, 1980 and tested the card on the system in September, 1980. Seven CC48s of the pilot production were installed in July, 1981. We mass-produced 35 more cards and finished installing them around the Main Ring in May, 1982. The author talks about the hardware, software and operation on the CC48 card, and he will make some remarks on his experience on the project

Voltage linear transformation circuit design

Science.gov (United States)

Sanchez, Lucas R. W.; Jin, Moon-Seob; Scott, R. Phillip; Luder, Ryan J.; Hart, Michael

2017-09-01

Many engineering projects require automated control of analog voltages over a specified range. We have developed a computer interface comprising custom hardware and MATLAB code to provide real-time control of a Thorlabs adaptive optics (AO) kit. The hardware interface includes an op amp cascade to linearly shift and scale a voltage range. With easy modifications, any linear transformation can be accommodated. In AO applications, the design is suitable to drive a range of different types of deformable and fast steering mirrors (FSM's). Our original motivation and application was to control an Optics in Motion (OIM) FSM which requires the customer to devise a unique interface to supply voltages to the mirror controller to set the mirror's angular deflection. The FSM is in an optical servo loop with a wave front sensor (WFS), which controls the dynamic behavior of the mirror's deflection. The code acquires wavefront data from the WFS and fits a plane, which is subsequently converted into its corresponding angular deflection. The FSM provides +/-3° optical angular deflection for a +/-10 V voltage swing. Voltages are applied to the mirror via a National Instruments digital-to-analog converter (DAC) followed by an op amp cascade circuit. This system has been integrated into our Thorlabs AO testbed which currently runs at 11 Hz, but with planned software upgrades, the system update rate is expected to improve to 500 Hz. To show that the FSM subsystem is ready for this speed, we conducted two different PID tuning runs at different step commands. Once 500 Hz is achieved, we plan to make the code and method for our interface solution freely available to the community.

Implementation of fuzzy-sliding mode based control of a grid connected photovoltaic system.

Science.gov (United States)

Menadi, Abdelkrim; Abdeddaim, Sabrina; Ghamri, Ahmed; Betka, Achour

2015-09-01

The present work describes an optimal operation of a small scale photovoltaic system connected to a micro-grid, based on both sliding mode and fuzzy logic control. Real time implementation is done through a dSPACE 1104 single board, controlling a boost chopper on the PV array side and a voltage source inverter (VSI) on the grid side. The sliding mode controller tracks permanently the maximum power of the PV array regardless of atmospheric condition variations, while The fuzzy logic controller (FLC) regulates the DC-link voltage, and ensures via current control of the VSI a quasi-total transit of the extracted PV power to the grid under a unity power factor operation. Simulation results, carried out via Matlab-Simulink package were approved through experiment, showing the effectiveness of the proposed control techniques. Copyright © 2015. Published by Elsevier Ltd.

Influence of the braking power control of the traction asynchronous machine in the voltage vector control system under DC

Directory of Open Access Journals (Sweden)

Юлія Олександрівна Слободенюк

2016-11-01

Full Text Available At braking the traction motors are transferred to generator mode and produce electrical energy which passes to the contact mains or storage device in the DC mains for further use. Such braking is called regenerative. The resulting electrical energy can be spent by trains in traction mode. Regenerative braking reduces the consumption of electric power for traction. In electric railways of our country more than 3% of the consumed electrical energy is given back to contact mains annually. As this takes place there arises the task to control the braking of the traction motors with minimal impact on electric power quality and maintaining proper braking performance. Based on the analysis of the characteristics of the brake traction of an electric locomotive with asynchronous electric machines the main braking modes have been chosen: at a constant sliding speed and the stator constant voltage; at constant braking power and the stator constant voltage; at a power value more than the nominal braking power; at a constant load torque; at a constant frequency of the stator. The vector control system with the formation of the reactive component of the stator current and the EMF regulator was chosen, basing on the working conditions characteristics in the electric braking mode (recuperation; namely, that the characteristics are defined by the laws regulating the frequency and voltage across the stator windings. This control system can fully reproduce any predetermined trajectory of traction and braking performance and adjust braking power. The offered system with recuperation can be used as a means of compensation in emergency situations with a power failure

Control and Protection in Low Voltage Grid with Large Scale Renewable Electricity Generation

DEFF Research Database (Denmark)

Mustafa, Ghullam

of the inverter controllers must be developed to Voltage-Frequency (VF) mode; and the others in either PV or PQ modes. The operation of the MG with several PV inverters and single VF inverter is similar to the operation of MG with a synchronous machine as slack bus. The VF inverter establishes the voltage...... of renewable energy based DGs are reduced CO2 emission, reduced operational cost as almost no fuel is used for their operation and less transmission and distribution losses as these units are normally built near to the load centers. This has also resulted in some operational challenges due to the unpredictable...... nature of such power generation sources. Some of the operational challenges include voltage variations due to power fluctuations coming from the DG units. On the other hand, it has also opened up some opportunities. One of the opportunities is islanding operation of the distribution system with DG unit...

Decentralized energy management strategy based on predictive controllers for a medium voltage direct current photovoltaic electric vehicle charging station

International Nuclear Information System (INIS)

Torreglosa, Juan P.; García-Triviño, Pablo; Fernández-Ramirez, Luis M.; Jurado, Francisco

2016-01-01

Highlights: • Electric vehicle charging station supplied by photovoltaic, batteries and grid connection is analyzed. • The bus voltage is the key parameter for controlling the system by decentralized approach. • Decentralized control approach facilities the enlargement of the system. • Photovoltaic and battery systems are controlled by model predictive controllers. • Response by model predictive controllers improves that by PI controllers. - Abstract: The use of distributed charging stations based on renewable energy sources for electric vehicles has increased in recent years. Combining photovoltaic solar energy and batteries as energy storage system, directly tied into a medium voltage direct current bus, and with the grid support, results to be an interesting option for improving the operation and efficiency of electric vehicle charging stations. In this paper, an electric vehicle charging station supplied by photovoltaic solar panels, batteries and with grid connection is analysed and evaluated. A decentralized energy management system is developed for regulating the energy flow among the photovoltaic system, the battery and the grid in order to achieve the efficient charging of electric vehicles. The medium voltage direct current bus voltage is the key parameter for controlling the system. The battery is controlled by a model predictive controller in order to keep the bus voltage at its reference value. Depending on the state-of-charge of the battery and the bus voltage, the photovoltaic system can work at maximum power point tracking mode or at bus voltage sustaining mode, or even the grid support can be needed. The results demonstrate the proper operation and energy management of the electric vehicle charging station under study.

Constant voltage and constant current control implementation for electric vehicles (evs) wireless charger

Science.gov (United States)

Tampubolon, Marojahan; Pamungkas, Laskar; Hsieh, Yao Ching; Chiu, Huang Jen

2018-04-01

This paper presents the implementation of Constant Voltage (CV) and Constant Current (CC) control for a wireless charger system. A battery charging system needs these control modes to ensure the safety of the battery and the effectiveness of the charging system. Here, the wireless charger system does not employ any post-regulator stage to control the output voltage and output current of the charger. But, it uses a variable frequency control incorporated with a conventional PI control. As a result, the size and the weight of the system are reduced. This paper discusses the brief review of the SS-WPT, control strategy and implementation of the CV and CC control. Experimental hardware with 2kW output power has been performed and tested. The results show that the proposed CV and CC control method works well with the system.

Autonomous Control of Current and Voltage Controlled DG Interface Inverters for Reactive Power Sharing and Harmonics Compensation in Islanded Microgrids

DEFF Research Database (Denmark)

Mousazadeh, Seyyed Yousef; Jalilain, Alireza; Savaghebi, Mehdi

2018-01-01

In microgrids, Voltage Source Inverters (VSIs) interfacing Distributed Generation (DG) units can be operated in Voltage or Current Controlled Modes (VCM/CCM). In this paper, a coordinated control of CCM and VCM units for reactive power sharing and voltage harmonics compensation is proposed....... This decentralized control scheme is based on the local measurement of signals. In this way, the need for communication links is removed which results in a simpler and more reliable structure compared to the communication based control structures. To be more exact, the VCM units contribute to harmonics compensation....... Experimental and simulation studies show that the harmonics compensation is achieved by using only local measurements in presence of virtual admittance/impedance schemes of CCM/VCM units. Furthermore, it is demonstrated that the reactive power sharing among the CCM and VCM units is obtained based...

Symmetric voltage-controlled variable resistance

Science.gov (United States)

Vanelli, J. C.

1978-01-01

Feedback network makes resistance of field-effect transistor (FET) same for current flowing in either direction. It combines control voltage with source and load voltages to give symmetric current/voltage characteristics. Since circuit produces same magnitude output voltage for current flowing in either direction, it introduces no offset in presense of altering polarity signals. It is therefore ideal for sensor and effector circuits in servocontrol systems.

Analysis of doubly-fed induction machine operating at motoring mode subjected to voltage sag

Directory of Open Access Journals (Sweden)

Navneet Kumar

2016-09-01

Full Text Available Variable Speed (VS Pumped Storage Plants (PSP equipped with large asynchronous (Doubly-Fed Induction machines are emerging now in hydropower applications. Motoring mode of operation of Doubly-Fed Induction Machine (DFIM is essential and techno-economical in this application due to: (1 its uniqueness in active power controllability, (2 bulk power handing capability with less rated power converters in rotor circuit, and (3 integrating Renewable Energy Sources (RES. This paper investigates the performance of two DFIMs at different power ratings (2.2 kW and 2 MW under voltage sag with different attribute. The test results are analyzed in terms of the peaks in torque, speed, power taken and transient currents in rotor and stator circuits. During sag, stable region for DFIM operation along with speed and stator side reactive power input control is also illustrated. The negative effects of voltage sag are briefly discussed. MATLAB simulation is validated with experimentation. The various observations during simulation and experimental analysis are also supported by the theoretical explanations.

Apple interface for experimental instrumentation and control-Pulse counter, timer, digital-to-analog converter, step motor and relays

International Nuclear Information System (INIS)

Souza, J.H.; Cernicchiaro, G.R.C.; Cavalcante, J.T.P.D.

1989-01-01

An interface plate for Apple II type microcomputer developed aiming to automatize measuring systems in which a TTL pulse counter, output of analogic voltage (with resolution of 12 bits), out put of step-motor control, relay drive, and timer for real time control, are necessary to carry-out the parallel tasks, is described. An application of this plate to a thermoluminescence reader is also presented. (M.C.K.) [pt

Micro controller application as x-ray machine's high voltage controller

International Nuclear Information System (INIS)

Wiranto Budi Santoso; Beny Syawaludin

2010-01-01

The micro controller application as x-ray machine's high voltage controller has been carried out. The purpose of this micro controller application is to give an accurate high voltage supply to the x-ray tube so that the x ray machine could produce the result as expected. The micro controller based X-ray machine's high voltage controller receives an input voltage from the keypad. This input value is displayed in the LCD (Liquid Crystal Display) screen. Then micro controller uses this input data to drive the stepper motor. The stepper motor adjusts the high voltage auto transformer's output according to the input value. The micro controller is programmed using BASCOM-B051 compiler. The test results show that the stepper motor could rotate according to an input value. (author)

Voltage-Sensitive Load Controllers for Voltage Regulation and Increased Load Factor in Distribution Systems

DEFF Research Database (Denmark)

Douglass, Philip James; Garcia-Valle, Rodrigo; Østergaard, Jacob

2014-01-01

This paper presents a novel controller design for controlling appliances based on local measurements of voltage. The controller finds the normalized voltage deviation accounting for the sensitivity of voltage measurements to appliance state. The controller produces a signal indicating desired pow...

Low Voltage CMOS Fully Differential Current Feedback Amplifier with Controllable 3-dB Bandwidth

International Nuclear Information System (INIS)

Madian, A.H.; Mahmoud, S.A.; Ashour, M.A.; Soliman, A.M.

2008-01-01

This paper presents a new CMOS fully differential current feedback operational amplifier with controllable 3-dB bandwidth suitable for analog data processing and acquisition applications. The FDCFOA has the advantage of a wide range controllable 3-dB bandwidth (∼57 MHz to 500 MHz) without changing the feedback resistance this guarantee the stability of the circuit. The FDCFOA has a standby current of 320μA. PSpice simulations of the FDCFOA block were given using 0.25μm CMOS technology from AMI MOSIS and dual supply voltages ±0.75 V

Advanced Control of the Dynamic Voltage Restorer for Mitigating Voltage Sags in Power Systems

Directory of Open Access Journals (Sweden)

Dung Vo Tien

2018-01-01

Full Text Available The paper presents a vector control with two cascaded loops to improve the properties of Dynamic Voltage Restorer (DVR to minimize Voltage Sags on the grid. Thereby, a vector controlled structure was built on the rotating dq-coordinate system with the combination of voltage control and the current control. The proposed DVR control method is modelled using MATLAB-Simulink. It is tested using balanced/unbalanced voltage sags as well as fluctuant and distorted voltages. As a result, by using this controlling method, the dynamic characteristics of the system have been improved significantly. The system performed with higher accuracy, faster response and lower distortion in the voltage sags compensation. The paper presents real time experimental results to verify the performance of the proposed method in real environments.

Fermilab accelerator control system: Analog monitoring facilities

International Nuclear Information System (INIS)

Seino, K.; Anderson, L.; Smedinghoff, J.

1987-10-01

Thousands of analog signals are monitored in different areas of the Fermilab accelerator complex. For general purposes, analog signals are sent over coaxial or twinaxial cables with varying lengths, collected at fan-in boxes and digitized with 12 bit multiplexed ADCs. For higher resolution requirements, analog signals are digitized at sources and are serially sent to the control system. This paper surveys ADC subsystems that are used with the accelerator control systems and discusses practical problems and solutions, and it describes how analog data are presented on the console system

Design and Control of a Dynamic Voltage Restorer

DEFF Research Database (Denmark)

Nielsen, John Godsk

voltage until the energy storage is completely drained or the voltages have returned to normal voltage levels. The control of the HV-DVR is a combined feedforward and feedback control to have a fast response time and load independent voltages. The control is implemented in a rotating dq-reference frame...... electric consumers against voltage dips and surges in the medium and low voltage distribution grid. The thesis first gives an introduction to relevant power quality issues for a DVR and power electronic controllers for voltage dip mitigation. Thereafter the operation and the elements in a DVR are described...... of symmetrical and non-symmetrical voltage dips. In most cases the DVR is capable of restoring the load voltages within 2 ms. During the transition phases load voltage oscillations can be generated and during the return of the supply voltages short time over-voltages can be generated by the DVR. Both...

Nonlinear Robust Control for Low Voltage Direct-Current Residential Microgrids with Constant Power Loads

Directory of Open Access Journals (Sweden)

Martín-Antonio Rodríguez-Licea

2018-05-01

Full Text Available A Direct Current (DC microgrid is a concept derived from a smart grid integrating DC renewable sources. The DC microgrids have three particularities: (1 integration of different power sources and local loads through a DC link; (2 on-site power source generation; and (3 alternating loads (on-off state. This kind of arrangement achieves high efficiency, reliability and versatility characteristics. The key device in the development of the DC microgrid is the power electronic converter (PEC, since it allows an efficient energy conversion between power sources and loads. However, alternating loads with strictly-controlled PECs can provide negative impedance behavior to the microgrid, acting as constant power loads (CPLs, such that the overall closed-loop system becomes unstable. Traditional CPL compensation techniques rely on a damping increment by the adaptation of the source or load voltage level, adding external circuitry or by using some advanced control technique. However, none of them provide a simple and general solution for the CPL problem when abrupt changes in parameters and/or in alternating loads/sources occur. This paper proposes a mathematical modeling and a robust control for the basic PECs dealing with CPLs in continuous conduction mode. In particular, the case of the low voltage residential DC microgrid with CPLs is taken as a benchmark. The proposed controller can be easily tuned for the desired response even by the non-expert. Basic converters with voltage mode control are taken as a basis to show the feasibility of this analysis, and experimental tests on a 100-W testbed include abrupt parameter changes such as input voltage.

Generation of multiple analog pulses with different duty cycles within VME control system for ICRH Aditya system

International Nuclear Information System (INIS)

Joshi, Ramesh; Singh, Manoj; Jadav, H M; Misra, Kishor; Kulkarni, S V

2010-01-01

Ion Cyclotron Resonance Heating (ICRH) is a promising heating method for a fusion device due to its localized power deposition profile, a direct ion heating at high density, and established technology for high RF power generation and transmission at low cost. Multiple analog pulse with different duty cycle in master of digital pulse for Data acquisition and Control system for steady state RF ICRH System(RF ICRH DAC) to be used for operating of RF Generator in Aditya to produce pre ionization and second analog pulse will produce heating. The control system software is based upon single digital pulse operation for RF source. It is planned to integrate multiple analog pulses with different duty cycle in master of digital pulse for Data acquisition and Control system for RF ICRH System(RF ICRH DAC) to be used for operating of RF Generator in Aditya tokamak. The task of RF ICRH DAC is to control and acquisition of all ICRH system operation with all control loop and acquisition for post analysis of data with java based tool. For pre ionization startup as well as heating experiments using multiple RF Power of different powers and duration. The experiment based upon the idea of using single RF generator to energize antenna inside the tokamak to radiate power twice, out of which first analog pulse will produce pre ionization and second analog pulse will produce heating. The whole system is based on standard client server technology using tcp/ip protocol. DAC Software is based on linux operating system for highly reliable, secure and stable system operation in failsafe manner. Client system is based on tcl/tk like toolkit for user interface with c/c++ like environment which is reliable programming languages widely used on stand alone system operation with server as vxWorks real time operating system like environment. The paper is focused on the Data acquisition and monitoring system software on Aditya RF ICRH System with analog pulses in slave mode with digital pulse in

Generation of multiple analog pulses with different duty cycles within VME control system for ICRH Aditya system

Science.gov (United States)

Joshi, Ramesh; Singh, Manoj; Jadav, H. M.; Misra, Kishor; Kulkarni, S. V.; ICRH-RF Group

2010-02-01

Ion Cyclotron Resonance Heating (ICRH) is a promising heating method for a fusion device due to its localized power deposition profile, a direct ion heating at high density, and established technology for high RF power generation and transmission at low cost. Multiple analog pulse with different duty cycle in master of digital pulse for Data acquisition and Control system for steady state RF ICRH System(RF ICRH DAC) to be used for operating of RF Generator in Aditya to produce pre ionization and second analog pulse will produce heating. The control system software is based upon single digital pulse operation for RF source. It is planned to integrate multiple analog pulses with different duty cycle in master of digital pulse for Data acquisition and Control system for RF ICRH System(RF ICRH DAC) to be used for operating of RF Generator in Aditya tokamak. The task of RF ICRH DAC is to control and acquisition of all ICRH system operation with all control loop and acquisition for post analysis of data with java based tool. For pre ionization startup as well as heating experiments using multiple RF Power of different powers and duration. The experiment based upon the idea of using single RF generator to energize antenna inside the tokamak to radiate power twise, out of which first analog pulse will produce pre ionization and second analog pulse will produce heating. The whole system is based on standard client server technology using tcp/ip protocol. DAC Software is based on linux operating system for highly reliable, secure and stable system operation in failsafe manner. Client system is based on tcl/tk like toolkit for user interface with c/c++ like environment which is reliable programming languages widely used on stand alone system operation with server as vxWorks real time operating system like environment. The paper is focused on the Data acquisition and monitoring system software on Aditya RF ICRH System with analog pulses in slave mode with digital pulse in

Generation of multiple analog pulses with different duty cycles within VME control system for ICRH Aditya system

Energy Technology Data Exchange (ETDEWEB)

Joshi, Ramesh; Singh, Manoj; Jadav, H M; Misra, Kishor; Kulkarni, S V, E-mail: rjoshi@ipr.res.i [Institute for plasma research, Bhat, Gandhinagar- 382428 (India)

2010-02-01

Ion Cyclotron Resonance Heating (ICRH) is a promising heating method for a fusion device due to its localized power deposition profile, a direct ion heating at high density, and established technology for high RF power generation and transmission at low cost. Multiple analog pulse with different duty cycle in master of digital pulse for Data acquisition and Control system for steady state RF ICRH System(RF ICRH DAC) to be used for operating of RF Generator in Aditya to produce pre ionization and second analog pulse will produce heating. The control system software is based upon single digital pulse operation for RF source. It is planned to integrate multiple analog pulses with different duty cycle in master of digital pulse for Data acquisition and Control system for RF ICRH System(RF ICRH DAC) to be used for operating of RF Generator in Aditya tokamak. The task of RF ICRH DAC is to control and acquisition of all ICRH system operation with all control loop and acquisition for post analysis of data with java based tool. For pre ionization startup as well as heating experiments using multiple RF Power of different powers and duration. The experiment based upon the idea of using single RF generator to energize antenna inside the tokamak to radiate power twice, out of which first analog pulse will produce pre ionization and second analog pulse will produce heating. The whole system is based on standard client server technology using tcp/ip protocol. DAC Software is based on linux operating system for highly reliable, secure and stable system operation in failsafe manner. Client system is based on tcl/tk like toolkit for user interface with c/c++ like environment which is reliable programming languages widely used on stand alone system operation with server as vxWorks real time operating system like environment. The paper is focused on the Data acquisition and monitoring system software on Aditya RF ICRH System with analog pulses in slave mode with digital pulse in

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...

Coordinated control for low voltage ride-through of a PMSG-based wind power plant

Directory of Open Access Journals (Sweden)

Khagendra Thapa

2016-01-01

Full Text Available Wind turbine generators should be kept connected to a power grid, while supporting the voltage recovery in the case of a grid fault to meet low voltage ride-through requirement in some grid codes. This paper proposes a coordinated control scheme that prevents the increase in the DC-link voltage by reducing the active power in the machine side converter of permanent magnet synchronous generators (PMSGs in proportion to the voltage dip at the terminal of PMSGs. The proposed scheme changes the current priorities from the active current to the reactive current to inject more reactive power for a severe fault depending on the voltage dip. In addition, the grid-side converter operates in a voltage control mode with the slope, which is the ratio of reactive current capability to the voltage tolerance around a rated value. Moreover, during the fault, the slope is changed depending on the voltage dip to inject more reactive current. The performance of the proposed scheme is validated for a wind power plant consisting of 20 units of 5-MW PMSGs using an EMTP-RV simulator. The results demonstrate that the scheme enables the PMSGs not only to survive during the fault, but also to provide a dynamic reactive power support.

Design of a High Performance Green-Mode PWM Controller IC with Smart Sensing Protection Circuits

Directory of Open Access Journals (Sweden)

Shen-Li Chen

2014-08-01

Full Text Available A design of high performance green-mode pulse-width-modulation (PWM controller IC with smart sensing protection circuits for the application of lithium-ion battery charger (1.52 V ~ 7.5 V is investigated in this paper. The protection circuits architecture of this system mainly bases on the lithium battery function and does for the system design standard of control circuit. In this work, the PWM controller will be with an automatic load sensing and judges the system operated in the operating mode or in the standby mode. Therefore, it reduces system’s power dissipation effectively and achieves the saving power target. In the same time, many protection sensing circuits such as: (1 over current protection (OCP and under current protection (UCP, (2 over voltage protection (OVP and under voltage protection (UVP, (3 loading determintion and short circuit protection (SCP, (4 over temperature protection (OTP, (5 VDD surge-spiking protection are included. Then, it has the characteristics of an effective monitoring the output loading and the harm prevention as a battery charging. Eventually, this green-mode pulse-width-modulation (PWM controller IC will be that the operation voltage is 3.3 V, the operation frequency is 0.98 MHz, and the output current range is from 454 mA to 500 mA. Meanwhile, the output convert efficiency is range from 74.8 % to 91 %, the power dissipation efficiency in green-mode is 25 %, and the operation temperature range is between -20 0C ~ 114 0C.

Voltage Support from Electric Vehicles in Distribution Grid

DEFF Research Database (Denmark)

Huang, Shaojun; Pillai, Jayakrishnan Radhakrishna; Bak-Jensen, Birgitte

2013-01-01

The paper evaluates the voltage support functions from electric vehicles (EVs) on a typical Danish distribution grid with high EV penetration. In addition to the popular voltage control modes, such as voltage droop charging (low voltage level leads to low charging power) and reactive power support...

Low-voltage CMOS operational amplifiers theory, design and implementation

CERN Document Server

Sakurai, Satoshi

1995-01-01

Low-Voltage CMOS Operational Amplifiers: Theory, Design and Implementation discusses both single and two-stage architectures. Opamps with constant-gm input stage are designed and their excellent performance over the rail-to-rail input common mode range is demonstrated. The first set of CMOS constant-gm input stages was introduced by a group from Technische Universiteit, Delft and Universiteit Twente, the Netherlands. These earlier versions of circuits are discussed, along with new circuits developed at the Ohio State University. The design, fabrication (MOSIS Tiny Chips), and characterization of the new circuits are now complete. Basic analog integrated circuit design concepts should be understood in order to fully appreciate the work presented. However, the topics are presented in a logical order and the circuits are explained in great detail, so that Low-Voltage CMOS Operational Amplifiers can be read and enjoyed by those without much experience in analog circuit design. It is an invaluable reference boo...

Burst mode control

DEFF Research Database (Denmark)

2015-01-01

to hysteresis on/off control, the new method does not require immediate responses to comparisons of a sense voltage to two reference voltages; rather, according to the new method, only one reference voltage is used, and delays in the feedback loop are allowed to cause some variation of an output of the power...

Direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp

Energy Technology Data Exchange (ETDEWEB)

Ljusev, P.; Andersen, Michael A.E.

2005-07-01

This paper discusses the advantages and problems when implementing direct energy conversion switching-mode audio power amplifiers. It is shown that the total integration of the power supply and Class D audio power amplifier into one compact direct converter can simplify design, increase efficiency and integration level, reduce product volume and lower its cost. As an example, the principle of operation and the measurements made on a direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp are presented. (au)

Direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp

DEFF Research Database (Denmark)

Ljusev, Petar; Andersen, Michael Andreas E.

2005-01-01

This paper discusses the advantages and problems when implementing direct energy conversion switching-mode audio power amplifiers. It is shown that the total integration of the power supply and Class D audio power amplifier into one compact direct converter can simplify the design, increase...... efficiency, reduce the product volume and lower its cost. As an example, the principle of operation and the measurements made on a direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp are presented....

Efficient 2,4-dichloronitrobenzene removal in the coupled BES-UASB reactor: Effect of external voltage mode.

Science.gov (United States)

Chen, Hui; Gao, Xinyi; Wang, Caiqin; Shao, Junjie; Xu, Xiangyang; Zhu, Liang

2017-10-01

In this study, bioelectrochemical-upflow anaerobic sludge blanket (BES-UASB) system was developed for treatment of 2,4-dichloronitrobenzen (DClNB) containing wastewater to investigate the effect of external voltage with different supplying modes. Results showed that 2,4-dichloroaniline (DClAN) was under detection limit in R1 (applied with intermittent voltage) and R2 (applied with continuous voltage) when the DClNB loading increased from 25 to 100gm 3 d -1 (hydraulic retention time (HRT) was decreased from 24 to 6h) while sudden accumulation of DClAN (1.7mgL -1 ) was observed in R0 (control). Dechlorination efficiency (DE) decreased to 32.7%, 45.0% and 45.3% in R0, R1 and R2 when HRT was further shortened to 4h. Microbial community analysis indicated the significant enrichment of dechlorination-related species in R1 and R2 compared with R0, e.g., Dehalobacter and Dehalococcoides. In summary, the BES-UASB system with intermittent voltage is an alternative process for efficient treatment of DClNB containing wastewater, and the energy input was reduced markedly. Copyright © 2017 Elsevier Ltd. All rights reserved.

Voltage control of ferromagnetic resonance

Directory of Open Access Journals (Sweden)

Ziyao Zhou

2016-06-01

Full Text Available Voltage control of magnetism in multiferroics, where the ferromagnetism and ferroelectricity are simultaneously exhibiting, is of great importance to achieve compact, fast and energy efficient voltage controllable magnetic/microwave devices. Particularly, these devices are widely used in radar, aircraft, cell phones and satellites, where volume, response time and energy consumption is critical. Researchers realized electric field tuning of magnetic properties like magnetization, magnetic anisotropy and permeability in varied multiferroic heterostructures such as bulk, thin films and nanostructure by different magnetoelectric (ME coupling mechanism: strain/stress, interfacial charge, spin–electromagnetic (EM coupling and exchange coupling, etc. In this review, we focus on voltage control of ferromagnetic resonance (FMR in multiferroics. ME coupling-induced FMR change is critical in microwave devices, where the electric field tuning of magnetic effective anisotropic field determines the tunability of the performance of microwave devices. Experimentally, FMR measurement technique is also an important method to determine the small effective magnetic field change in small amount of magnetic material precisely due to its high sensitivity and to reveal the deep science of multiferroics, especially, voltage control of magnetism in novel mechanisms like interfacial charge, spin–EM coupling and exchange coupling.

Design of a High Linearity Four-Quadrant Analog Multiplier in Wideband Frequency Range

Directory of Open Access Journals (Sweden)

Abdul kareem Mokif Obais

2017-05-01

Full Text Available In this paper, a voltage mode four quadrant analog multiplier in the wideband frequency rangeis designed using a wideband operational amplifier (OPAMP and squaring circuits. The wideband OPAMP is designed using 10 identical NMOS transistorsand operated with supply voltages of ±12V. Two NMOS transistors and two wideband OPAMP are utilized in the design of the proposed squaring circuit. All the NMOS transistors are based on 0.35µm NMOStechnology. The multiplier has input and output voltage ranges of ±10 V, high range of linearity from -10 V to +10 V, and cutoff frequency of about 5 GHz. The proposed multiplier is designed on PSpice in Orcad 16.6

Dynamic performance enhancement of microgrids by advanced sliding mode controller

Energy Technology Data Exchange (ETDEWEB)

Sofla, Mohammadhassan Abdollahi [Electrical Engineering and Computer Science Dept., University of Toledo, Ohio (United States); Gharehpetian, Gevorg B. [Electrical Engineering Dept., Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

2011-01-15

Dynamics are the most important problems in the microgrid operation. In the islanded microgrid, the mismatch of parallel operations of inverters during dynamics can result in the instability. This paper considers severe dynamics which can occur in the microgrid. Microgrid can have different configurations with different load and generation dynamics which are facing voltage disturbances. As a result, microgrid has many uncertainties and is placed in the distribution network where is full of voltage disturbances. Moreover, characteristics of the distribution network and distributed energy resources in the islanded mode make microgrid vulnerable and easily lead to instability. The main aim of this paper is to discuss the suitable mathematical modeling based on microgrid characteristics and to design properly inner controllers to enhance the dynamics of microgrid with uncertain and changing parameters. This paper provides a method for inner controllers of inverter-based distributed energy resources to have a suitable response for different dynamics. Parallel inverters in distribution networks were considered to be controlled by nonlinear robust voltage and current controllers. Theoretical prove beyond simulation results, reveal evidently the effectiveness of the proposed controller. (author)

Sliding-Mode Control Design of a Boost-Buck Switching Converter for AC Signal Generation

OpenAIRE

Biel Solé, Domingo; Guinjoan Gispert, Francisco; Fossas Colet, Enric; Chavarría Roé, Javier

2004-01-01

This paper presents a sliding-mode control design of a boost–buck switching converter for a voltage step-up dc–ac conversion without the use of any transformer. This approach combines the step-up/step-down conversion ratio capability of the converter with the robustness properties of sliding-mode control. The proposed control strategy is based on the design of two slidingcontrol laws, one ensuring the control of a full-bridge buck converter for proper dc–ac conversion, and the other one the c...

Design automation of switching mode high voltage power supply for nuclear instruments

International Nuclear Information System (INIS)

El-araby, S.M.S.

1999-01-01

This paper presents an automation procedure for the design of switching mode high voltage power supplies, using Pc programming facility. The procedure permits the selection of a ready made or designed ferrite transformer. This selection could be achieved according to the designer desire; as the program includes complete information about ready made ferrite transformer through complete database. The procedure is based on suggested template circuit. Micro-Cap IV simulation package is used to verify the desired high voltage power supply design. Simulation results agree quite well with suggested procedure's results. Design aspects and development needed to increase automation capabilities are also discussed

Computer controlled high voltage system

Energy Technology Data Exchange (ETDEWEB)

Kunov, B; Georgiev, G; Dimitrov, L [and others

1996-12-31

A multichannel computer controlled high-voltage power supply system is developed. The basic technical parameters of the system are: output voltage -100-3000 V, output current - 0-3 mA, maximum number of channels in one crate - 78. 3 refs.

Voltage Balancing Control of Diode-Clamped Multilevel Inverter

Directory of Open Access Journals (Sweden)

ŞCHIOP Adrian

2013-10-01

Full Text Available In this paper is developed a control scheme for mono-phase diode clamped inverter to achieve balancing voltages on inverter capacitors. First, it develops a control scheme without taking into account the need to balance voltage on two capacitors. It examines the effects on the output voltage inverter, and then it realizes two control schemes that will balance the voltages. The simulations of control schemes were performed in OrCAD Pspice.

Toward Wireless Health Monitoring via an Analog Signal Compression-Based Biosensing Platform.

Science.gov (United States)

Zhao, Xueyuan; Sadhu, Vidyasagar; Le, Tuan; Pompili, Dario; Javanmard, Mehdi

2018-06-01

Wireless all-analog biosensor design for the concurrent microfluidic and physiological signal monitoring is presented in this paper. The key component is an all-analog circuit capable of compressing two analog sources into one analog signal by the analog joint source-channel coding (AJSCC). Two circuit designs are discussed, including the stacked-voltage-controlled voltage source (VCVS) design with the fixed number of levels, and an improved design, which supports a flexible number of AJSCC levels. Experimental results are presented on the wireless biosensor prototype, composed of printed circuit board realizations of the stacked-VCVS design. Furthermore, circuit simulation and wireless link simulation results are presented on the improved design. Results indicate that the proposed wireless biosensor is well suited for sensing two biological signals simultaneously with high accuracy, and can be applied to a wide variety of low-power and low-cost wireless continuous health monitoring applications.

High-Voltage-Input Level Translator Using Standard CMOS

Science.gov (United States)

Yager, Jeremy A.; Mojarradi, Mohammad M.; Vo, Tuan A.; Blalock, Benjamin J.

2011-01-01

proposed integrated circuit would translate (1) a pair of input signals having a low differential potential and a possibly high common-mode potential into (2) a pair of output signals having the same low differential potential and a low common-mode potential. As used here, "low" and "high" refer to potentials that are, respectively, below or above the nominal supply potential (3.3 V) at which standard complementary metal oxide/semiconductor (CMOS) integrated circuits are designed to operate. The input common-mode potential could lie between 0 and 10 V; the output common-mode potential would be 2 V. This translation would make it possible to process the pair of signals by use of standard 3.3-V CMOS analog and/or mixed-signal (analog and digital) circuitry on the same integrated-circuit chip. A schematic of the circuit is shown in the figure. Standard 3.3-V CMOS circuitry cannot withstand input potentials greater than about 4 V. However, there are many applications that involve low-differential-potential, high-common-mode-potential input signal pairs and in which standard 3.3-V CMOS circuitry, which is relatively inexpensive, would be the most appropriate circuitry for performing other functions on the integrated-circuit chip that handles the high-potential input signals. Thus, there is a need to combine high-voltage input circuitry with standard low-voltage CMOS circuitry on the same integrated-circuit chip. The proposed circuit would satisfy this need. In the proposed circuit, the input signals would be coupled into both a level-shifting pair and a common-mode-sensing pair of CMOS transistors. The output of the level-shifting pair would be fed as input to a differential pair of transistors. The resulting differential current output would pass through six standoff transistors to be mirrored into an output branch by four heterojunction bipolar transistors. The mirrored differential current would be converted back to potential by a pair of diode-connected transistors

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

Voltage-controlled radial wrinkles of a trumpet-like dielectric elastomer structure

Science.gov (United States)

Mao, Guoyong; Wu, Lei; Fu, Yimou; Liu, Junjie; Qu, Shaoxing

2018-03-01

Wrinkle is usually considered as one failure mode of membrane structure. However, it can also be harnessed in developing smart devices such as dry adhesion tape, diffraction grating, smart window, etc. In this paper, we present a method to generate voltage-controlled radial wrinkles, which are fast response and reversible, in a stretched circular dielectric elastomer (DE) membrane with boundary fixed. In the experiment, we bond a circular plate on the center of the circular membrane and then pull the DE membrane perpendicular to itself via the plate. The stretched DE membrane is a trumpet-like structure. When the stretched DE membrane is subjected to a certain voltage, wrinkles nucleate from the center of the DE membrane and propagate to the boundary as the voltage increases. We adopt a theoretical framework to analyze the nucleation of the wrinkles. A simple wavelength expression is achieved, which is only related to the geometry and the stretch of the DE membrane. Results show that the theory agrees well with the experiment. This work may help the future design of DE actuators in avoiding mechanical instability and provide a new method to generate controllable radial DE wrinkles.

Performance Analysis of Phase Controlled Unidirectional and Bidirectional AC Voltage Controllers

Directory of Open Access Journals (Sweden)

Abdul Sattar Larik

2011-01-01

Full Text Available AC voltage controllers are used to vary the output ac voltage from a fixed ac input source. They are also commonly called ac voltage regulators or ac choppers. The output voltage is either controlled by PAC (Phase Angle Control method or on-off control method. Due to various advantages of ac voltage controllers, such as high efficiency, simplicity, low cost and ability to control large amount of power they efficiently control the speed of ac motors, light dimming and industrial heating, etc. These converters are variable structure systems and generate harmonics during the operation which will affect the power quality when connected to system network. During the last couple of years, a number of new semiconductor devices and various power electronic converters has been introduced. Accordingly the subject of harmonics and its problems are of great concern to power industry and customers. In this research work, initially the simulation models of single phase unidirectional and bidirectional ac voltage controllers were developed by using MATLAB software. The harmonics of these models are investigated by simulation. In the end, the harmonics were also analyzed experimentally. The simulated as well as experimental results are presented.

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

International Nuclear Information System (INIS)

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

2012-01-01

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.

Current-voltage characteristics of carbon nanostructured field emitters in different power supply modes

Science.gov (United States)

Popov, E. O.; Kolosko, A. G.; Filippov, S. V.; Romanov, P. A.; Terukov, E. I.; Shchegolkov, A. V.; Tkachev, A. G.

2017-12-01

We received and compared the current-voltage characteristics of large-area field emitters based on nanocomposites with graphene and nanotubes. The characteristics were measured in two high voltage scanning modes: the "slow" and the "fast". Correlation between two types of hysteresis observed in these regimes was determined. Conditions for transition from "reverse" hysteresis to the "direct" one were experimentally defined. Analysis of the eight-shaped hysteresis was provided with calculation of the effective emission parameters. The phenomenological model of adsorption-desorption processes in the field emission system was proposed.

Design of the all solid high-voltage power supply for a gyrotron body

Energy Technology Data Exchange (ETDEWEB)

Rao, Yihua [School of Mathematics and Physics, University of South China, Hengyang, 421001 (China); Chen, Wenguang, E-mail: 430000485393@usc.edu.cn [School of Electrical Engineering, University of South China, Hengyang, 421001 (China); Hu, Bo [School of Electrical Engineering, University of South China, Hengyang, 421001 (China); Rao, Jun; Huang, Mei; Kang, Zihua; Feng, Kun [Southwestern Institute of Physics, Chengdu, 610041 (China); Huang, Jiaqi [School of Electrical Engineering, University of South China, Hengyang, 421001 (China)

2017-04-15

Highlights: • Completed design of all solid-state high-voltage power supply for gyrotron body on HL-2M ECRH. • Consist of 58 PSM modules and one BUCK module, controlled by DSP system. • Fabricated full voltage 35 kV, 200 mA BPS and tested in dummy load. • The BPS can operate in three modes: single pulse mode, multi-pulse modulation mode and the six-level preset mode. - Abstract: Gyrotron plays an important role in the research of electron cyclotron resonance heating (ECRH) on Tokomak. The high-frequency switched power supply technology and pulse step modulation (PSM) technology are used in the development of the all solid high-voltage body power supply (BPS) for 1 MW/105 GHz Gyrotron on ECRH system. Firstly, the basic structure of the BPS and its control system are introduced. Secondly, the software control algorithm of voltage stabilization and modulate method are developed. Finally, the design is verified by the experiments. The experimental results of the single pulse mode, the multi-pulse modulation mode and the six-level preset mode, are shown. The output voltage of the power supply can reach 35 kV and the current at about 200 mA, which are adjustable in the full range. The maximum modulation frequency can reach 1 kHz and the front edge of the pulse can be adjust from 0 to 3 ms and the accuracy of the output voltage is less than 100 V. The results show that the control method is feasible and can be applied to other high power microwave sources.

Piezo Voltage Controlled Planar Hall Effect Devices.

Science.gov (United States)

Zhang, Bao; Meng, Kang-Kang; Yang, Mei-Yin; Edmonds, K W; Zhang, Hao; Cai, Kai-Ming; Sheng, Yu; Zhang, Nan; Ji, Yang; Zhao, Jian-Hua; Zheng, Hou-Zhi; Wang, Kai-You

2016-06-22

The electrical control of the magnetization switching in ferromagnets is highly desired for future spintronic applications. Here we report on hybrid piezoelectric (PZT)/ferromagnetic (Co2FeAl) devices in which the planar Hall voltage in the ferromagnetic layer is tuned solely by piezo voltages. The change of planar Hall voltage is associated with magnetization switching through 90° in the plane under piezo voltages. Room temperature magnetic NOT and NOR gates are demonstrated based on the piezo voltage controlled Co2FeAl planar Hall effect devices without the external magnetic field. Our demonstration may lead to the realization of both information storage and processing using ferromagnetic materials.

Coordinated Voltage Control of Active Distribution Network

Directory of Open Access Journals (Sweden)

Xie Jiang

2016-01-01

Full Text Available This paper presents a centralized coordinated voltage control method for active distribution network to solve off-limit problem of voltage after incorporation of distributed generation (DG. The proposed method consists of two parts, it coordinated primal-dual interior point method-based voltage regulation schemes of DG reactive powers and capacitors with centralized on-load tap changer (OLTC controlling method which utilizes system’s maximum and minimum voltages, to improve the qualified rate of voltage and reduce the operation numbers of OLTC. The proposed coordination has considered the cost of capacitors. The method is tested using a radial edited IEEE-33 nodes distribution network which is modelled using MATLAB.

Time-division-multiplex control scheme for voltage multiplier rectifiers

Directory of Open Access Journals (Sweden)

Bin-Han Liu

2017-03-01

Full Text Available A voltage multiplier rectifier with a novel time-division-multiplexing (TDM control scheme for high step-up converters is proposed in this study. In the proposed TDM control scheme, two full-wave voltage doubler rectifiers can be combined to realise a voltage quadrupler rectifier. The proposed voltage quadrupler rectifier can reduce transformer turn ratio and transformer size for high step-up converters and also reduce voltage stress for the output capacitors and rectifier diodes. An N-times voltage rectifier can be straightforwardly produced by extending the concepts from the proposed TDM control scheme. A phase-shift full-bridge (PSFB converter is adopted in the primary side of the proposed voltage quadrupler rectifier to construct a PSFB quadrupler converter. Experimental results for the PSFB quadrupler converter demonstrate the performance of the proposed TDM control scheme for voltage quadrupler rectifiers. An 8-times voltage rectifier is simulated to determine the validity of extending the proposed TDM control scheme to realise an N-times voltage rectifier. Experimental and simulation results show that the proposed TDM control scheme has great potential to be used in high step-up converters.

Voltage Controlled Dynamic Demand Response

DEFF Research Database (Denmark)

Bhattarai, Bishnu Prasad; Bak-Jensen, Birgitte; Mahat, Pukar

2013-01-01

Future power system is expected to be characterized by increased penetration of intermittent sources. Random and rapid fluctuations in demands together with intermittency in generation impose new challenges for power balancing in the existing system. Conventional techniques of balancing by large...... central or dispersed generations might not be sufficient for future scenario. One of the effective methods to cope with this scenario is to enable demand response. This paper proposes a dynamic voltage regulation based demand response technique to be applied in low voltage (LV) distribution feeders....... An adaptive dynamic model has been developed to determine composite voltage dependency of an aggregated load on feeder level. Following the demand dispatch or control signal, optimum voltage setting at the LV substation is determined based on the voltage dependency of the load. Furthermore, a new technique...

Investigation of phase-wise voltage regulator control logics for compensating voltage deviations in an experimental low voltage network

DEFF Research Database (Denmark)

Hu, Junjie; Zecchino, Antonio; Marinelli, Mattia

2016-01-01

This paper investigates the control logics of an on-load tap-changer (OLTC) transformer by means of an experimental system validation. The experimental low-voltage unbalanced system consists of a decoupled single-phase OLTC transformer, a 75-metre 16 mm2 cable, a controllable single-phase resistive...... load and an electric vehicle, which has the vehicle-to-grid function. Three control logics of the OLTC transformer are described in the study. The three control logics are classified based on their control objectives and control inputs, which include network currents and voltages, and can be measured...... either locally or remotely. To evaluate and compare the control performances of the three control logics, all the tests use the same loading profiles. The experimental results indicate that the modified line compensation control can regulate voltage in a safe band in the case of various load...

275 C Downhole Switched-Mode Power Supply

Energy Technology Data Exchange (ETDEWEB)

Chris Hutchens; Vijay Madhuravasal

2008-08-31

A vee-square (V2) control based controller IC is developed for a switch mode power supply capable of operating at extreme temperature/harsh environment conditions. A buck type regulator with silicon carbide power junction field effect transistors (JFET) as power devices is used to analyze the performance of controller. Special emphases are made on the analog sub-blocks--voltage reference, operational transconductance amplifier and comparator as individual building blocks. Transformer coupled gate drives and high temperature operable magnetic cores and capacitors are identified and tested for use in the design. Conventional ceramic chip packaging of ICs combined with lead carrier type mounting of passive filter components is introduced for hybrid packaging of the complete product. The developed SMPS is anticipated to support the operation of down-hole microcontrollers and other electronics devices that require low/medium power filtered dc inputs over an operating temperature of 275 C.

DVCCs Based High Input Impedance Voltage-Mode First-Order Filters Employing Grounded Capacitor and Resistor

Directory of Open Access Journals (Sweden)

J. W. Horng

2010-12-01

Full Text Available A voltage-mode high input impedance first-order highpass, lowpass and allpass filters using two differential voltage current conveyors (DVCCs, one grounded capacitor and one grounded resistor is presented. The highpass, lowpass and allpass signals can be obtained simultaneously from the circuit configuration. The suggested filter uses a canonical number of passive components without requiring any component matching condition. The simulation results confirm the theoretical analysis.

PID Controller of Sprayer Chassis by Sliding Mode

Directory of Open Access Journals (Sweden)

Hua Zhang

2017-01-01

Full Text Available In order to solve the straight line drive coordinated control problem of the four-wheel independent drive sprayer chassis, the dynamic model of sprayer chassis and electromagnetic proportional valve controlled hydraulic motor model are established. The additional yaw moment is designed to rectify the deviation with sliding mode variable structure control. PID control strategy is used to calculate the control voltage adjustment of the electromagnetic proportional valve. The simulation results show that the accumulative deviation of the chassis is 0.2 m out of 100 m when the coordinated control strategy is adopted on different adhesive coefficient pavement, which is much smaller than the value without control. The test results of test prototype show that the yaw acceleration of the chassis can be as low as −0.0132 m/s2 on different adhesive coefficient pavement with coordinated control, which is smaller than the value without control, and the straight line drive requirements are met. It is feasible to combine sliding mode variable structure with PID control and use the electromagnetic proportional control technology in the straight line drive coordinated control of sprayer chassis by adding the yaw moment to rectify the deviation of chassis based on the yaw acceleration detection.

A dynamic voltage restorer (DVR) with selective harmonic compensation at medium voltage level

DEFF Research Database (Denmark)

Newman, M.J.; Holmes, D.G.; Nielsen, J.G.

2005-01-01

Dynamic voltage restorers (DVRs) are now becoming more established in industry to reduce the impact of voltage sags to sensitive loads. However, DVRs spend most of their time in standby mode, since voltage sags occur very infrequently, and hence their utilization is low. In principle, it would...... be advantageous if the series-connected inverter of a DVR could also be used to compensate for any steady-state load voltage harmonics, since this would increase the power quality "value-added" benefits to the grid system. However, before this can be done, consideration must be given to the control of steady......-state power through the DVR, the increased losses, and the low modulation depths at which the scheme must operate to achieve acceptable harmonic compensation performance. This paper presents a selective harmonic feedback control strategy that can be easily added to medium-voltage DVR systems to provide...

Double input converters for different voltage sources with isolated charger

Directory of Open Access Journals (Sweden)

Chalash Sattayarak

2014-09-01

Full Text Available This paper presents the double input converters for different voltage input sources with isolated charger coils. This research aims to increase the performance of the battery charger circuit. In the circuit, there are the different voltage levels of input source. The operating modes of the switch in the circuit use the microcontroller to control the battery charge and to control discharge mode automatically when the input voltage sources are lost from the system. The experimental result of this research shows better performance for charging at any time period of the switch, while the voltage input sources work together. Therefore, this research can use and develop to battery charger for present or future.

Microprocessor-controlled, programmable ramp voltage generator

International Nuclear Information System (INIS)

Hopwood, J.

1978-11-01

A special-purpose voltage generator has been developed for driving the quadrupole mass filter of a residual gas analyzer. The generator is microprocessor-controlled with desired ramping parameters programmed by setting front-panel digital thumb switches. The start voltage, stop voltage, and time of each excursion are selectable. A maximum of five start-stop levels may be pre-selected for each program. The ramp voltage is 0 to 10 volts with sweep times from 0.1 to 999.99 seconds

10-bit rapid single flux quantum digital-to-analog converter for ac voltage standard

International Nuclear Information System (INIS)

Maezawa, M; Hirayama, F

2008-01-01

Digital-to-analog (D/A) converters based on rapid single flux quantum (RSFQ) technology are under development for ac voltage standard applications. We present design and test results on a prototype 10-bit version integrated on a single chip. The 10-bit chip includes over 6000 Josephson junctions and consumes a bias current exceeding 1 A. To reduce the effects of the high bias current on circuit operation, a custom design method was employed in part and large circuit blocks were divided into smaller ones. The 10-bit chips were fabricated and tested at low speed. The test results suggested that our design approach could manage large bias currents on the order of 1 A per chip

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.

Sliding Mode Control of a Bidirectional Buck/Boost DC-DC Converter with Constant Switching Frequency

Directory of Open Access Journals (Sweden)

A. Safari

2018-03-01

Full Text Available In this paper, sliding mode control (SMC for a bidirectional buck/boost DC-DC converter (BDC with constant frequency in continuous conduction mode (CCM is discussed. Since the converter is a high-order converter, the reduced-order sliding manifold is exploited. Because of right-half-plan zero (RHPZ in the converter’s duty ratio to output voltage transfer function, sliding mode current controller is used. This controller benefits from various advantages such as fast dynamic response, robustness, stable and small variation of the settling time over a wide range of operation conditions. Because the converter operates in both step-down and step-up modes, two sliding manifold is derived for each mode. The existence and stability conditions are analyzed for both SMC in step-down and step-up modes. Finally, Simulation results are also provided to justify the feasibility of the controller using MATLAB/Simulink.

Controlling the layer localization of gapless states in bilayer graphene with a gate voltage

Science.gov (United States)

Jaskólski, W.; Pelc, M.; Bryant, Garnett W.; Chico, Leonor; Ayuela, A.

2018-04-01

Experiments in gated bilayer graphene with stacking domain walls present topological gapless states protected by no-valley mixing. Here we research these states under gate voltages using atomistic models, which allow us to elucidate their origin. We find that the gate potential controls the layer localization of the two states, which switches non-trivially between layers depending on the applied gate voltage magnitude. We also show how these bilayer gapless states arise from bands of single-layer graphene by analyzing the formation of carbon bonds between layers. Based on this analysis we provide a model Hamiltonian with analytical solutions, which explains the layer localization as a function of the ratio between the applied potential and interlayer hopping. Our results open a route for the manipulation of gapless states in electronic devices, analogous to the proposed writing and reading memories in topological insulators.

NETWORK-CENTRIC TECHNOLOGIES FOR CONTROL OF THREE-PHASE NETWORK OPERATION MODES

Directory of Open Access Journals (Sweden)

Ye. I. Sokol

2017-06-01

Full Text Available Purpose. The development of the control system for three-phase network is based on intelligent technologies of network-centric control of heterogeneous objects. The introduction of unmanned aerial vehicles for monitoring of three-phase network increases the efficiency of management. Methodology. The case of decomposition of the instantaneous capacities of the fixed and variable components for 3-wire system. The features of power balance for the different modes of its functioning. It should be noted that symmetric sinusoidal mode is balanced and good, but really unbalanced, if the standard reactive power is not zero. To solve the problem of compensation is sufficient knowledge of the total value of the inactive components of full power (value of the inactive power without detail. The creation of a methodology of measurement and assessment will require knowledge of the magnitudes of each inactive component separately, which leads to the development of a unified approach to the measurement and compensation of inactive components of full power and the development of a generalized theory of power. Results. Procedure for the compensation of the current of zero sequence excludes from circuit the source, as the active component of instantaneous power of zero sequence, and a vector due to a current of zero sequence. This procedure is performed without time delay as it does not require integration. Only a 3–wire system with symmetrical voltage eliminates pulsations and symmetrization of the equivalent conductances of the phases of the task. Under asymmetric voltage, the power is different, its analysis requires the creation of a vector mathematical model of the energy processes of asymmetrical modes of 3–phase systems. Originality. The proposed method extends the basis of the vector method for any zero sequence voltages and shows that the various theories of instantaneous power three wired scheme due to the choice of a basis in a two

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...... is introduced in the controller, which is necessary in order to reduce the dc-bus voltage ripple and active power harmonics at the same time. The proposed control topology is implemented in the lab. Simulation and experimental results are provided to validate its performance and the analysis presented...

Automated Cryocooler Monitor and Control System

Science.gov (United States)

Britcliffe, Michael J.; Hanscon, Theodore R.; Fowler, Larry E.

2011-01-01

A system was designed to automate cryogenically cooled low-noise amplifier systems used in the NASA Deep Space Network. It automates the entire operation of the system including cool-down, warm-up, and performance monitoring. The system is based on a single-board computer with custom software and hardware to monitor and control the cryogenic operation of the system. The system provides local display and control, and can be operated remotely via a Web interface. The system controller is based on a commercial single-board computer with onboard data acquisition capability. The commercial hardware includes a microprocessor, an LCD (liquid crystal display), seven LED (light emitting diode) displays, a seven-key keypad, an Ethernet interface, 40 digital I/O (input/output) ports, 11 A/D (analog to digital) inputs, four D/A (digital to analog) outputs, and an external relay board to control the high-current devices. The temperature sensors used are commercial silicon diode devices that provide a non-linear voltage output proportional to temperature. The devices are excited with a 10-microamp bias current. The system is capable of monitoring and displaying three temperatures. The vacuum sensors are commercial thermistor devices. The output of the sensors is a non-linear voltage proportional to vacuum pressure in the 1-Torr to 1-millitorr range. Two sensors are used. One measures the vacuum pressure in the cryocooler and the other the pressure at the input to the vacuum pump. The helium pressure sensor is a commercial device that provides a linear voltage output from 1 to 5 volts, corresponding to a gas pressure from 0 to 3.5 MPa (approx. = 500 psig). Control of the vacuum process is accomplished with a commercial electrically operated solenoid valve. A commercial motor starter is used to control the input power of the compressor. The warm-up heaters are commercial power resistors sized to provide the appropriate power for the thermal mass of the particular system, and

Dynamics and stabilization of peak current-mode controlled buck converter with constant current load

Science.gov (United States)

Leng, Min-Rui; Zhou, Guo-Hua; Zhang, Kai-Tun; Li, Zhen-Hua

2015-10-01

The discrete iterative map model of peak current-mode controlled buck converter with constant current load (CCL), containing the output voltage feedback and ramp compensation, is established in this paper. Based on this model the complex dynamics of this converter is investigated by analyzing bifurcation diagrams and the Lyapunov exponent spectrum. The effects of ramp compensation and output voltage feedback on the stability of the converter are investigated. Experimental results verify the simulation and theoretical analysis. The stability boundary and chaos boundary are obtained under the theoretical conditions of period-doubling bifurcation and border collision. It is found that there are four operation regions in the peak current-mode controlled buck converter with CCL due to period-doubling bifurcation and border-collision bifurcation. Research results indicate that ramp compensation can extend the stable operation range and transfer the operating mode, and output voltage feedback can eventually eliminate the coexisting fast-slow scale instability. Project supported by the National Natural Science Foundation of China (Grant No. 61371033), the Fok Ying-Tung Education Foundation for Young Teachers in the Higher Education Institutions of China (Grant No. 142027), the Sichuan Provincial Youth Science and Technology Fund, China (Grant Nos. 2014JQ0015 and 2013JQ0033), and the Fundamental Research Funds for the Central Universities, China (Grant No. SWJTU11CX029).

A Riding-through Technique for Seamless Transition between Islanded and Grid-Connected Modes of Droop-Controlled Inverters

DEFF Research Database (Denmark)

Hu, Shang-hung; Lee, Tzung-Lin; Kuo, Chun-Yi

2016-01-01

This paper presents a seamless transition method for a droop-controlled inverter. The droop control is suitable to make the inverter work as a voltage source in both islanded and grid-connected modes, however, the transfer between theses modes can result in a big inrush current that may damage...... a smooth transition between them, requiring neither synchronization signals nor grid-side information. The control algorithm and design procedure are presented. Experimental results from a laboratory prototype validate the effectiveness of the proposed method....... the system. The proposed method allows the droop-controlled inverter to improve the transient response when transferring between modes, by detecting the inrush current, activating a current control loop during transients, and then transferring back to droop-controlled mode smoothly by using a virtual...

Analogical study of the servo-control of a reactivity modulator

International Nuclear Information System (INIS)

Le Bot, Michel

1969-03-01

In the context of the study of the transfer functions related to the Cabri reactor, this paper presents: the objective of the servo-control (reactivity modulator, reasons for the analogical study), the principles of the servo-control (description of the servo-controlled system, elaboration of the error signal, principles of the phase meter, critical analysis of different types of phase meters), the analogical formulation (transfer diagram of the process, analogical simulation of the process, analogical realization of the phase meter, simulation of the Low Frequency generator), study of the controlled system and results (system responses to echelon and ramp signals, responses of the controlled system with the phase meter in feedback)

Resonance analysis in parallel voltage-controlled Distributed Generation inverters

DEFF Research Database (Denmark)

Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

2013-01-01

Thanks to the fast responses of the inner voltage and current control loops, the dynamic behaviors of parallel voltage-controlled Distributed Generation (DG) inverters not only relies on the stability of load sharing among them, but subjects to the interactions between the voltage control loops...

Sensorless Control of IPMSM by Voltage Injection

DEFF Research Database (Denmark)

Matzen, Torben N.; Bech, Michael Møller

2006-01-01

In this paper a sensorless discrete current control of an Interior Permanent Magnet Synchrouns Motor (IPMSM) by voltage injection is designed and tested. The whole controller is operating in the dq-frame and for this reason the rotor position is essential to know, to transform between the station......In this paper a sensorless discrete current control of an Interior Permanent Magnet Synchrouns Motor (IPMSM) by voltage injection is designed and tested. The whole controller is operating in the dq-frame and for this reason the rotor position is essential to know, to transform between...... the stationary frame and the rotor xed dq-frame. To obtain the position even at standstill a sensorless scheme using voltage injection is added to the current controller....

Design of CMOS analog integrated fractional-order circuits applications in medicine and biology

CERN Document Server

Tsirimokou, Georgia; Elwakil, Ahmed

2017-01-01

This book describes the design and realization of analog fractional-order circuits, which are suitable for on-chip implementation, capable of low-voltage operation and electronic adjustment of their characteristics. The authors provide a brief introduction to fractional-order calculus, followed by design issues for fractional-order circuits of various orders and types. The benefits of this approach are demonstrated with current-mode and voltage-mode filter designs. Electronically tunable emulators of fractional-order capacitors and inductors are presented, where the behavior of the corresponding chips fabricated using the AMS 0.35um CMOS process has been experimentally verified. Applications of fractional-order circuits are demonstrated, including a pre-processing stage suitable for the implementation of the Pan-Tompkins algorithm for detecting the QRS complexes of an electrocardiogram (ECG), a fully tunable implementation of the Cole-Cole model used for the modeling of biological tissues, and a simple, non-i...

Common voltage eliminating of SVM diode clamping three-level inverter connected to grid

DEFF Research Database (Denmark)

Guo, Yougui; Zeng, Ping; Zhu, Jieqiong

2011-01-01

A novel method of common voltage eliminating is put forward for SVM diode clamping three-level inverter connected to grid by calculation of common voltage of its various switching states. PLECS is used to model this three-level inverter connected to grid and good results are obtained. First...... analysis of common mode voltage for switching states of diode clamping 3-level inverter is given in detail. Second the common mode voltage eliminating control strategy of SVM is described for diode clamping three-level inverter. Third, PLECS is briefly introduced. Fourth, the modeling of diode clamping...... three-level inverter is presented with PLECS. Finally, a series of simulations are carried out. The simulation results tell us PLECS is a very powerful tool to real power circuits modeling. They have also verified that proposed common mode voltage eliminating control strategy of SVM is feasible...

Optimal Switching Table-Based Sliding Mode Control of an Energy Recovery Li-Ion Power Accumulator Battery Pack Testing System

Directory of Open Access Journals (Sweden)

Kil To Chong

2013-10-01

Full Text Available The main objective of the present work is to apply a sliding mode controller (SMC to medium voltage and high power output energy recovery Li-ion power accumulator battery pack testing systems (ERLPABTSs, which are composed of a three-level neutral-point-clamped (NPC three-phase voltage source inverter (VSI and a two-level buck-boost converter without an isolating transformer. An inner current decoupled control scheme for the aforementioned system is proposed and two sliding mode planes for active and reactive current control are designed based on the control scheme. An optimized switching table for current convergence is used according to the error sign of the equivalent input voltage and feedback voltage. The proposed ERLPABTS could be used to integrate discharging energy into the power grid when performing high accuracy current testing. The active and reactive power references for the grid-connected inverter are determined based on the discharging energy from the DC-DC converter. Simulations and experiments on a laboratory hardware platform using a 175 kW insulated gate bipolar transistor (IGBT-based ERLPABTS have been implemented and verified, and the performance is found satisfactory and superior to conventional ERLPABPTS.

Improved adaptive input voltage control of a solar array interfacing current mode controlled boost power stage

International Nuclear Information System (INIS)

Sitbon, Moshe; Schacham, Shmuel; Suntio, Teuvo; Kuperman, Alon

2015-01-01

Highlights: • Photovoltaic generator dynamic resistance online estimation method is proposed. • Control method allowing to achieve nominal performance at all time is presented. • The method is suitable for any type of photovoltaic system. - Abstract: Nonlinear characteristics of photovoltaic generators were recently shown to significantly influence the dynamics of interfacing power stages. Moreover, since the dynamic resistance of photovoltaic generators is both operating point and environmental variables dependent, the combined dynamics exhibits these dependencies as well, burdening control challenge. Typically, linear time invariant input voltage loop controllers (e.g. Proportional-Integrative-Derivative) are utilized in photovoltaic applications, designed according to nominal operating conditions. Nevertheless, since actual dynamics is seldom nominal, closed loop performance of such systems varies as well. In this paper, adaptive control method is proposed, allowing to estimate photovoltaic generator resistance online and utilize it to modify the controller parameters such that closed loop performance remains nominal throughout the whole operation range. Unlike previously proposed method, utilizing double-grid-frequency component for estimation purposes and suffering from various drawbacks such as operation point dependence and applicability to single-phase grid connected systems only, the proposed method is based on harmonic current injection and is independent on operating point and system topology

The Study of Operation Modes and Control Strategies of a Multidirectional MC for Battery Based System

Directory of Open Access Journals (Sweden)

Saman Toosi

2015-01-01

Full Text Available To enhance the performance of stand-alone battery based system and to achieve the continuous power transmission, the behavior of multidirectional matrix converter (MDMC has been analyzed in different operation modes. A systematic method interfacing a renewable source, a storage battery, and a load is proposed for a stand-alone battery based power system (SABBPS to utilize the MDMC as PWM converter, inverter, or PWM converter and inverter in different operation modes. In this study, the Extended Direct Duty Pulse Width Modulation (EDDPWM technique has been applied to control the power flow path between the renewable source, load, and the battery. Corresponding to generator voltage, input frequency, and loads demands, several operating states and control strategies are possible. Therefore, the boundaries and distribution of operation modes are discussed and illustrated to improve the system performance. The mathematical equation of the EDDPWM under different operation modes has been derived to achieve the maximum voltage ratio in each mode. The theoretical and modulation concepts presented have been verified in simulation using MATLAB and experimental testing. Moreover, the THD, ripple, and power flow direction have been analyzed for output current to investigate the behavior of system in each operation mode.

Cross Voltage Control with Inner Hysteresis Current Control for Multi-output Boost Converter

DEFF Research Database (Denmark)

Nami, Alireza; Zare, Firuz; Blaabjerg, Frede

2009-01-01

Multi-output boost (MOB) converter is a novel DC-DC converter unlike the regular boost converter, has the ability to share its total output voltage and to have different series output voltage from a given duty cycle for low and high power applications. In this paper, discrete voltage control...... with inner hysteresis current control loop has been proposed to keep the simplicity of the control law for the double-output MOB converter, which can be implemented by a combination of analogue and logical ICs or simple microcontroller to constrain the output voltages of MOB converter at their reference...... voltages against variation in load or input voltage. The salient features of the proposed control strategy are simplicity of implementation and ease to extend to multiple outputs in the MOB converter. Simulation and experimental results are presented to show the validity of control strategy....

Analog techniques in CEBAF's RF control system

International Nuclear Information System (INIS)

Hovater, C.; Fugitt, J.

1989-01-01

Recent developments in high-speed analog technology have progressed into the areas of traditional RF technology. Diode related devices are being replaced by analog IC's in the CEBAF RF control system. Complex phase modulators and attenuators have been successfully tested at 70 MHz. They have three advantages over existing technology: lower cost, less temperature sensitivity, and more linearity. RF signal conditioning components and how to implement the new analog IC's will be covered in this paper. 4 refs., 5 figs

Analog techniques in CEBAF'S RF control system

International Nuclear Information System (INIS)

Hovater, C.; Fugitt, J.

1989-01-01

Recent developments in high-speed analog technology have progressed into the areas of traditional rf technology. Diode-related devices are being replaced by analog IC's in the CEBAF rf control system. Complex phase modulators and attenuators have been successfully tested at 70 MHz. They have three advantages over existing technology: lower cost, less temperature sensitivity, and more linearity. Rf signal conditioning components and how to implement the new analog IC's will be covered in this paper. 4 refs., 5 figs

The transfer voltage standard for calibration outside of a laboratory

Directory of Open Access Journals (Sweden)

Urekar Marjan

2017-01-01

Full Text Available The transfer voltage standard is designed for transferring the analog voltage from a calibrator to the process control workstation for multi-electrode electrolysis process in a plating plant. Transfer voltage standard is based on polypropylene capacitors and operational amplifiers with tera-ohm range input resistance needed for capacitor self-discharging effect cancellation. Dielectric absorption effect is described. An instrument for comparison of reference and control voltages is devised, based on precise window comparator. Detailed description of the main task is given, including constraints, theoretical and practical solutions. Procedure for usage of the standard outside of a laboratory conditions is explained. Comparison of expected and realized standard characteristics is given. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR-32019

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.

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

Digital redesign of anti-wind-up controller for cascaded analog system.

Science.gov (United States)

Chen, Y S; Tsai, J S H; Shieh, L S; Moussighi, M M

2003-01-01

The cascaded conventional anti-wind-up (CAW) design method for integral controller is discussed. Then, the prediction-based digital redesign methodology is utilized to find the new pulse amplitude modulated (PAM) digital controller for effective digital control of the analog plant with input saturation constraint. The desired digital controller is determined from existing or pre-designed CAW analog controller. The proposed method provides a novel methodology for indirect digital design of a continuous-time unity output-feedback system with a cascaded analog controller as in the case of PID controllers for industrial control processes with the presence of actuator saturations. It enables us to implement an existing or pre-designed cascaded CAW analog controller via a digital controller effectively.

Sliding mode control and observation

CERN Document Server

Shtessel, Yuri; Fridman, Leonid; Levant, Arie

2014-01-01

The sliding mode control methodology has proven effective in dealing with complex dynamical systems affected by disturbances, uncertainties and unmodeled dynamics. Robust control technology based on this methodology has been applied to many real-world problems, especially in the areas of aerospace control, electric power systems, electromechanical systems, and robotics. Sliding Mode Control and Observation represents the first textbook that starts with classical sliding mode control techniques and progresses toward newly developed higher-order sliding mode control and observation algorithms and their applications. The present volume addresses a range of sliding mode control issues, including: *Conventional sliding mode controller and observer design *Second-order sliding mode controllers and differentiators *Frequency domain analysis of conventional and second-order sliding mode controllers *Higher-order sliding mode controllers and differentiators *Higher-order sliding mode observers *Sliding mode disturbanc...

Second-order sliding mode control for DFIG-based wind turbines fault ride-through capability enhancement.

Science.gov (United States)

Benbouzid, Mohamed; Beltran, Brice; Amirat, Yassine; Yao, Gang; Han, Jingang; Mangel, Hervé

2014-05-01

This paper deals with the fault ride-through capability assessment of a doubly fed induction generator-based wind turbine using a high-order sliding mode control. Indeed, it has been recently suggested that sliding mode control is a solution of choice to the fault ride-through problem. In this context, this paper proposes a second-order sliding mode as an improved solution that handle the classical sliding mode chattering problem. Indeed, the main and attractive features of high-order sliding modes are robustness against external disturbances, the grids faults in particular, and chattering-free behavior (no extra mechanical stress on the wind turbine drive train). Simulations using the NREL FAST code on a 1.5-MW wind turbine are carried out to evaluate ride-through performance of the proposed high-order sliding mode control strategy in case of grid frequency variations and unbalanced voltage sags. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Design of practical sliding-mode controllers with constant switching frequency for power converters

Energy Technology Data Exchange (ETDEWEB)

Navarro-Lopez, Eva M. [School of Computer Science, Centre for Interdisciplinary Computational and Dynamical Analysis, The University of Manchester, Oxford Road, Kilburn Building, Manchester M13 9PL (United Kingdom); Cortes, Domingo [Seccion de Mecatronica, Departamento de Ingenieria Electrica, CINVESTAV-IPN, Av. IPN 2508, Col. San Pedro Zacatenco, 07360 Mexico City (Mexico); Castro, Christian [Centro de Investigacion en Computacion del IPN, Av. Jose Othon de Mendizabal s/n, Col. Nueva Industrial Vallejo, 07738 Mexico City (Mexico)

2009-05-15

A novel experimentally motivated method in order to design a family of easy-to-implement sliding-mode controllers for power converters is proposed. Two main results are presented. First, the relation between sliding-mode control and average control is reinterpreted so that the limitation of the switching frequency for the closed-loop system is achieved in a more direct way than other methods so far reported in the literature. For this purpose, a class of sliding surfaces which makes the associated equivalent control be the system average control is proposed. Second, the achievement of a constant switching frequency in the controlled system is assured without requiring the sliding-mode-based controller to be modified, unlike most previous works. As a result, the proposed sliding surfaces-type can be directly implemented via a pulse-width modulator. The control methodology is implemented for the voltage control in a boost converter prototype in which the load is considered unknown. Experimental results confirm high performance and robustness under parameters variation. Furthermore, the solution proposed is easy to implement and well-suited for other power converters. (author)

Grid to Standalone Transition Motion-Sensorless Dual-Inverter Control of PMSG With Asymmetrical Grid Voltage Sags and Harmonics Filtering

DEFF Research Database (Denmark)

Fatu, M.; Blaabjerg, Frede; Boldea, I.

2014-01-01

This paper describes a variable-speed motion-sensorless control system for permanent-magnet synchronous generator (PMSG) connected to grid via back-to-back inverters for wind energy generation. The grid-side inverter control system employs proportional-integral (PI) current controllers with cross...... and automatic seamless transfer method from grid connected to stand alone and vice versa. In stand-alone mode, a voltage control scheme with selective harmonic compensation is employed. The PMSG motion-sensorless control system uses an active power controller and a PLL-based observer to estimate the rotor...... and voltage harmonics compensation. While some of the aforementioned issues have been treated rather individually in previous conference publications of the authors, the present paper integrates them into a comprehensive control system of PMSG....

Voltage-Controlled Floating Resistor Using DDCC

Directory of Open Access Journals (Sweden)

M. Kumngern

2011-04-01

Full Text Available This paper presents a new simple configuration to realize the voltage-controlled floating resistor, which is suitable for integrated circuit implementation. The proposed resistor is composed of three main components: MOS transistor operating in the non-saturation region, DDCC, and MOS voltage divider. The MOS transistor operating in the non-saturation region is used to configure a floating linear resistor. The DDCC and the MOS transistor voltage divider are used for canceling the nonlinear component term of MOS transistor in the non-saturation region to obtain a linear current/voltage relationship. The DDCC is employed to provide a simple summer of the circuit. This circuit offers an ease for realizing the voltage divider circuit and the temperature effect that includes in term of threshold voltage can be compensated. The proposed configuration employs only 16 MOS transistors. The performances of the proposed circuit are simulated with PSPICE to confirm the presented theory.

A compact control system to achieve stable voltage and low jitter trigger for repetitive intense electron-beam accelerator based on resonant charging

Science.gov (United States)

Qiu, Yongfeng; Liu, Jinliang; Yang, Jianhua; Cheng, Xinbing; Yang, Xiao

2017-08-01

A compact control system based on Delphi and Field Programmable Gate Array(FPGA) is developed for a repetitive intense electron-beam accelerator(IEBA), whose output power is 10GW and pulse duration is 160ns. The system uses both hardware and software solutions. It comprises a host computer, a communication module and a main control unit. A device independent applications programming interface, devised using Delphi, is installed on the host computer. Stability theory of voltage in repetitive mode is analyzed and a detailed overview of the hardware and software configuration is presented. High voltage experiment showed that the control system fulfilled the requests of remote operation and data-acquisition. The control system based on a time-sequence control method is used to keep constant of the voltage of the primary capacitor in every shot, which ensured the stable and reliable operation of the electron beam accelerator in the repetitive mode during the experiment. Compared with the former control system based on Labview and PIC micro-controller developed in our laboratory, the present one is more compact, and with higher precision in the time dimension. It is particularly useful for automatic control of IEBA in the high power microwave effects research experiments where pulse-to-pulse reproducibility is required.

Enhanced Two-Stage Hierarchical Control for a Dual Mode WECS-Based Microgrid

Directory of Open Access Journals (Sweden)

Rasool M. Imran

2018-05-01

Full Text Available Along with the great benefits of utilizing renewable energy (e.g., wind energy in the power system, there are also some issues, such as increasing the uncertainty and reducing the system inertia. Communication-based centralized control has started to play a significant role in reacting to the aforementioned issues, especially for relatively small systems, such as microgrids. In this context, in this paper, an enhanced communication-based hierarchical control for a dual mode wind energy conversion system-based microgrid is modeled and investigated. The primary stage utilized the P-V/Q-f droop method, which is the preferred droop method to be used in microgrids when the line impedance is mainly resistive. The secondary stage relied on an enhanced methodology for compensating the deviations of voltage and frequency and improving the performance of the microgrid during small and large signal disturbances. Moreover, as this microgrid operates in a dual mode, the mode transition cases from grid-tied mode to autonomous mode and vice versa have been addressed. Thereafter, an improved control scheme for the unplanned outage transition and a modified control scheme for the pre-synchronization and reconnection transition were proposed. Finally, the proposed work was evaluated by the simulation results in MATLAB environment.

Optical control system for high-voltage terminals

International Nuclear Information System (INIS)

Bicek, J.J.

1978-01-01

An optical control system for the control of devices in the terminal of an electrostatic accelerator includes a laser that is modulated by a series of preselected codes produced by an encoder. A photodiode receiver is placed in the laser beam at the high-voltage terminal of an electrostatic accelerator. A decoder connected to the photodiode decodes the signals to provide control impulses for a plurality of devices at the high voltage of the terminal

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...

Coordinated single-phase control scheme for voltage unbalance reduction in low voltage network.

Science.gov (United States)

Pullaguram, Deepak; Mishra, Sukumar; Senroy, Nilanjan

2017-08-13

Low voltage (LV) distribution systems are typically unbalanced in nature due to unbalanced loading and unsymmetrical line configuration. This situation is further aggravated by single-phase power injections. A coordinated control scheme is proposed for single-phase sources, to reduce voltage unbalance. A consensus-based coordination is achieved using a multi-agent system, where each agent estimates the averaged global voltage and current magnitudes of individual phases in the LV network. These estimated values are used to modify the reference power of individual single-phase sources, to ensure system-wide balanced voltages and proper power sharing among sources connected to the same phase. Further, the high X / R ratio of the filter, used in the inverter of the single-phase source, enables control of reactive power, to minimize voltage unbalance locally. The proposed scheme is validated by simulating a LV distribution network with multiple single-phase sources subjected to various perturbations.This article is part of the themed issue 'Energy management: flexibility, risk and optimization'. © 2017 The Author(s).

Grid Voltage Modulated Control of Grid-Connected Voltage Source Inverters under Unbalanced Grid Conditions

DEFF Research Database (Denmark)

Li, Mingshen; Gui, Yonghao; Quintero, Juan Carlos Vasquez

2017-01-01

In this paper, an improved grid voltage modulated control (GVM) with power compensation is proposed for grid-connected voltage inverters when the grid voltage is unbalanced. The objective of the proposed control is to remove the power ripple and to improve current quality. Three power compensation...... objectives are selected to eliminate the negative sequence components of currents. The modified GVM method is designed to obtain two separate second-order systems for not only the fast convergence rate of the instantaneous active and reactive powers but also the robust performance. In addition, this method...

Single DV-DXCCII Based Voltage Controlled First Order All-pass Filter with Inverting and Non-inverting responses

Directory of Open Access Journals (Sweden)

B Chaturvedi

2015-12-01

Full Text Available In this paper, a new voltage controlled first order all-pass filter is presented. The proposed circuit employs a single differential voltage dual-X second generation current conveyor (DV-DXCCII and a grounded capacitor only. The proposed all-pass filter provides both inverting and non inverting voltage-mode outputs from the same configuration simultaneously without any matching condition. Non-ideal analysis along with sensitivity analysis is also investigated. The proposed circuit has low active and passive sensitivities. As an application the proposed all-pass filter is connected in cascade to get higher order filter. The theoretical results are validated thorough PSPICE simulations using TSMC 0.18µm CMOS process parameters.

A current mode feed-forward gain control system for a 0.8 V CMOS hearing aid

Energy Technology Data Exchange (ETDEWEB)

Li Fanyang; Yang Haigang; Liu Fei; Yin Tao, E-mail: yanghg@mail.ie.ac.cn [Institute of Electronics, Chinese Academy of Sciences, Beijing 100080 (China)

2011-06-15

A current mode feed-forward gain control (CMFGC) technique is presented, which is applied in the front-end system of a hearing aid chip. Compared with conventional automatic gain control (AGC), CMFGC significantly improves the total harmonic distortion (THD) by digital gain control. To attain the digital gain control codes according to the extremely weak output signal from the microphone, a rectifier and a state controller implemented in current mode are proposed. A prototype chip has been designed based on a 0.13 {mu}m standard CMOS process. The measurement results show that the supply voltage can be as low as 0.6 V. And with the 0.8 V supply voltage, the THD is improved and below 0.06% (-64 dB) at the output level of 500 mV{sub p-p}, yet the power consumption is limited to 40 {mu}W. In addition, the input referred noise is only 4 {mu}V{sub rms} and the maximum gain is maintained at 33 dB. (semiconductor integrated circuits)

A current mode feed-forward gain control system for a 0.8 V CMOS hearing aid

International Nuclear Information System (INIS)

Li Fanyang; Yang Haigang; Liu Fei; Yin Tao

2011-01-01

A current mode feed-forward gain control (CMFGC) technique is presented, which is applied in the front-end system of a hearing aid chip. Compared with conventional automatic gain control (AGC), CMFGC significantly improves the total harmonic distortion (THD) by digital gain control. To attain the digital gain control codes according to the extremely weak output signal from the microphone, a rectifier and a state controller implemented in current mode are proposed. A prototype chip has been designed based on a 0.13 μm standard CMOS process. The measurement results show that the supply voltage can be as low as 0.6 V. And with the 0.8 V supply voltage, the THD is improved and below 0.06% (-64 dB) at the output level of 500 mV p-p , yet the power consumption is limited to 40 μW. In addition, the input referred noise is only 4 μV rms and the maximum gain is maintained at 33 dB. (semiconductor integrated circuits)

A differential low-voltage high gain current-mode integrated RF receiver front-end

Energy Technology Data Exchange (ETDEWEB)

Wang Chunhua; Ma Minglin; Sun Jingru; Du Sichun; Guo Xiaorong; He Haizhen, E-mail: wch1227164@sina.com [School of Information Science and Technology, Hunan University, Changsha 410082 (China)

2011-02-15

A differential low-voltage high gain current-mode integrated RF front end for an 802.11b WLAN is proposed. It contains a differential transconductance low noise amplifier (G{sub m}-LNA) and a differential current-mode down converted mixer. The single terminal of the G{sub m}-LNA contains just one MOS transistor, two capacitors and two inductors. The gate-source shunt capacitors, C{sub x1} and C{sub x2}, can not only reduce the effects of gate-source C{sub gs} on resonance frequency and input-matching impedance, but they also enable the gate inductance L{sub g1,2} to be selected at a very small value. The current-mode mixer is composed of four switched current mirrors. Adjusting the ratio of the drain channel sizes of the switched current mirrors can increase the gain of the mixer and accordingly increase the gain of RF receiver front-end. The RF front-end operates under 1 V supply voltage. The receiver RFIC was fabricated using a chartered 0.18 {mu}m CMOS process. The integrated RF receiver front-end has a measured power conversion gain of 17.48 dB and an input referred third-order intercept point (IIP3) of -7.02 dBm. The total noise figure is 4.5 dB and the power is only 14 mW by post-simulations. (semiconductor integrated circuits)

Usability Assessment of Two Different Control Modes for the Master Console of a Laparoscopic Surgical Robot

Directory of Open Access Journals (Sweden)

Xiaoli Zhang

2012-01-01

Full Text Available The objective of this study is to evaluate potential interface control modes for a compact four-degree-of-freedom (4-DOF surgical robot. The goal is to improve robot usability by incorporating a sophisticated haptics-capable interface. Two control modes were developed using a commercially available haptic joystick: (1 a virtually point-constrained interface providing an analog for constrained laparoscopic motion (3-DOF rotation and 1-DOF translation, and (2 an unconstrained Cartesian input interface mapping more directly to the surgical tool tip motions. Subjects (n = 5 successfully performed tissue identification and manipulation tasks in an animal model in point-constrained and unconstrained control modes, respectively, with speed roughly equal to that achieved in similar manual procedures, and without a steep learning curve. The robot control was evaluated through bench-top tests and a subsequent qualitative questionnaire (n = 15. The results suggest that the unconstrained control mode was preferred for both camera guidance and tool manipulations.

Secondary Control for Voltage Quality Enhancement in Microgrids

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Jalilian, Alireza; Vasquez, Juan Carlos

2012-01-01

In this paper, a hierarchical control scheme is proposed for enhancement of sensitive load bus (SLB) voltage quality in microgrids. The control structure consists of primary and secondary levels. The primary control level comprises distributed generators (DGs) local controllers. Each of these con......In this paper, a hierarchical control scheme is proposed for enhancement of sensitive load bus (SLB) voltage quality in microgrids. The control structure consists of primary and secondary levels. The primary control level comprises distributed generators (DGs) local controllers. Each...

Alternator control for battery charging

Energy Technology Data Exchange (ETDEWEB)

Brunstetter, Craig A.; Jaye, John R.; Tallarek, Glen E.; Adams, Joseph B.

2015-07-14

In accordance with an aspect of the present disclosure, an electrical system for an automotive vehicle has an electrical generating machine and a battery. A set point voltage, which sets an output voltage of the electrical generating machine, is set by an electronic control unit (ECU). The ECU selects one of a plurality of control modes for controlling the alternator based on an operating state of the vehicle as determined from vehicle operating parameters. The ECU selects a range for the set point voltage based on the selected control mode and then sets the set point voltage within the range based on feedback parameters for that control mode. In an aspect, the control modes include a trickle charge mode and battery charge current is the feedback parameter and the ECU controls the set point voltage within the range to maintain a predetermined battery charge current.

Control and Testing of a Dynamic Voltage Restorer (DVR) at Medium Voltage Level

DEFF Research Database (Denmark)

Nielsen, John Godsk; Newman, Michael; Nielsen, Hans Ove

2004-01-01

power sensitive loads from voltage sags. This paper reports practical test results obtained on a medium voltage (10 kV) level using a DVR at a Distribution test facility in Kyndby, Denmark. The DVR was designed to protect a 400-kVA load from a 0.5-p.u. maximum voltage sag. The reported DVR verifies......The dynamic voltage restorer (DVR) has become popular as a cost effective solution for the protection of sensitive loads from voltage sags. Implementations of the DVR have been proposed at both a low voltage (LV) level, as well as a medium voltage (MV) level; and give an opportunity to protect high...... the use of a feed-forward and feed-back technique of the controller and it obtains both good transient and steady state responses. The effect of the DVR on the system is experimentally investigated under both faulted and non-faulted system states, for a variety of linear and non-linear loads. Variable...

Sliding mode direct power control of RSC for DFIGs driven by variable speed wind turbines

Directory of Open Access Journals (Sweden)

E.G. Shehata

2015-12-01

Full Text Available In spite of its several advantages, a classic direct power control (DPC of doubly fed induction generators (DFIGs driven by variable speed wind turbines has some drawbacks. In this paper, a simple and robust total sliding mode controller (TSMC is designed to improve the classical DPC performance without complicating the overall scheme. The TSMC is designed to regulate the DFIG stator active and reactive powers. Two integral switching functions are selected for describing the switching surfaces of the active and reactive powers. Reaching phase stability problem of the classical sliding mode controller is avoided in the proposed TSMC. Neither current control loops nor accurate values of machine parameters are required in the proposed scheme. In addition, axes transformation of the stator voltage and current are eliminated. The grid side converter is controlled based on DPC principle to regulate both DC-link voltage and total reactive power. The feasibility of the proposed DPC scheme is validated through simulation studies on a 1.5 MW wind power generation system. The performance of the proposed and conventional DPC schemes is compared under different operating conditions.

Dynamic Sliding Mode Evolution PWM Controller for a Novel High-Gain Interleaved DC-DC Converter in PV System

Directory of Open Access Journals (Sweden)

Taizhou Bei

2014-01-01

Full Text Available Considering the disadvantages of the traditional high-gain DC-DC converter such as big size, high voltage stress of switches, and large input current ripple, a novel high-gain interleaved boost converter with coupled-inductor and switched-capacitor was proposed correspondingly and the operation principle together with the steady-state analysis of this converter was also described. Besides, a new control approach-dynamic sliding mode evolution PWM controller (DSME PWM for the novel topological converter based on both dynamic evolution and sliding mode control was also presented. From the simulation results and experimental validation the proposed converter can fulfill high-gain boost, low ripple of both the input current and the output voltage. Furthermore, MPPT technique can be also achieved in a short time by simulation. The efficiency and stability of the converter proposed in this paper can be improved.

Control Of Stepper Motor Movement By DC Voltage

International Nuclear Information System (INIS)

Gayani, Didi; Margono; Indasah, Iin; Sugito

2000-01-01

Instrumentation for controlling the power of reactor of TRIGA Mark II uses the stepper motor to move the control rod of neutron absorbers. The direction and speed of control rod movement are determined by the polarity and the amplitude of DC voltage as an error signal that is the difference of set point of power and the power of being measured on the control system. The unit of stepper motor controller of reactor instrumentation of TRIGA Mark II uses patent module of trade Mark of Vexta, USA. In this chance, the electronic circuit is made to function as the control of stepper motor movement by using the DC voltage to anticipate the problem may be faced in case of repair and maintenance of reactor instrumentation. As a result of experiment, it is stated that the control of motor movement by using DC voltage is performed into 2 stages. First, by making the oscillator that is proportional to the positive DC voltage. Secondly, by making the translator to translate the oscillator signal to be a logic pattern for controlling the movement of stepper motor. Translator and motor driver are made by using the L297 and L298 as a pair of stepper motor controller of SGS T HOMSON

Voltage-sensing domain mode shift is coupled to the activation gate by the N-terminal tail of hERG channels.

Science.gov (United States)

Tan, Peter S; Perry, Matthew D; Ng, Chai Ann; Vandenberg, Jamie I; Hill, Adam P

2012-09-01

Human ether-a-go-go-related gene (hERG) potassium channels exhibit unique gating kinetics characterized by unusually slow activation and deactivation. The N terminus of the channel, which contains an amphipathic helix and an unstructured tail, has been shown to be involved in regulation of this slow deactivation. However, the mechanism of how this occurs and the connection between voltage-sensing domain (VSD) return and closing of the gate are unclear. To examine this relationship, we have used voltage-clamp fluorometry to simultaneously measure VSD motion and gate closure in N-terminally truncated constructs. We report that mode shifting of the hERG VSD results in a corresponding shift in the voltage-dependent equilibrium of channel closing and that at negative potentials, coupling of the mode-shifted VSD to the gate defines the rate of channel closure. Deletion of the first 25 aa from the N terminus of hERG does not alter mode shifting of the VSD but uncouples the shift from closure of the cytoplasmic gate. Based on these observations, we propose the N-terminal tail as an adaptor that couples voltage sensor return to gate closure to define slow deactivation gating in hERG channels. Furthermore, because the mode shift occurs on a time scale relevant to the cardiac action potential, we suggest a physiological role for this phenomenon in maximizing current flow through hERG channels during repolarization.

Secondary Control Scheme for Voltage Unbalance Compensation in an Islanded Droop-Controlled Microgrid

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Jalilian, Alireza; Vasquez, Juan Carlos

2012-01-01

The concept of microgrid hierarchical control is presented recently. In this paper, a hierarchical scheme is proposed which includes primary and secondary control levels. The primary level comprises distributed generators (DGs) local controllers. The local controllers mainly consist of power......, voltage and current controllers, and virtual impedance control loop. The central secondary controller is designed to manage the compensation of voltage unbalance at the point of common coupling (PCC) in an islanded microgrid. Unbalance compensation is achieved by sending proper control signals to the DGs...... local controllers. The design procedure of the control system is discussed in detail and the simulation results are presented. The results show the effectiveness of the proposed control structure in compensating the voltage unbalance....

Current–voltage characteristics of high-voltage 4H-SiC p{sup +}–n{sub 0}–n{sup +} diodes in the avalanche breakdown mode

Energy Technology Data Exchange (ETDEWEB)

Ivanov, P. A., E-mail: Pavel.Ivanov@mail.ioffe.ru; Potapov, A. S.; Samsonova, T. P.; Grekhov, I. V. [Ioffe Physical–Technical Institute (Russian Federation)

2017-03-15

p{sup +}–n{sub 0}–n{sup +} 4H-SiC diodes with homogeneous avalanche breakdown at 1860 V are fabricated. The pulse current–voltage characteristics are measured in the avalanche-breakdown mode up to a current density of 4000 A/cm{sup 2}. It is shown that the avalanche-breakdown voltage increases with increasing temperature. The following diode parameters are determined: the avalanche resistance (8.6 × 10{sup –2} Ω cm{sup 2}), the electron drift velocity in the n{sub 0} base at electric fields higher than 10{sup 6} V/cm (7.8 × 10{sup 6} cm/s), and the relative temperature coefficient of the breakdown voltage (2.1 × 10{sup –4} K{sup –1}).

Digitally controlled analog proportional-integral-derivative (PID) controller for high-speed scanning probe microscopy

Science.gov (United States)

Dukic, Maja; Todorov, Vencislav; Andany, Santiago; Nievergelt, Adrian P.; Yang, Chen; Hosseini, Nahid; Fantner, Georg E.

2017-12-01

Nearly all scanning probe microscopes (SPMs) contain a feedback controller, which is used to move the scanner in the direction of the z-axis in order to maintain a constant setpoint based on the tip-sample interaction. The most frequently used feedback controller in SPMs is the proportional-integral (PI) controller. The bandwidth of the PI controller presents one of the speed limiting factors in high-speed SPMs, where higher bandwidths enable faster scanning speeds and higher imaging resolution. Most SPM systems use digital signal processor-based PI feedback controllers, which require analog-to-digital and digital-to-analog converters. These converters introduce additional feedback delays which limit the achievable imaging speed and resolution. In this paper, we present a digitally controlled analog proportional-integral-derivative (PID) controller. The controller implementation allows tunability of the PID gains over a large amplification and frequency range, while also providing precise control of the system and reproducibility of the gain parameters. By using the analog PID controller, we were able to perform successful atomic force microscopy imaging of a standard silicon calibration grating at line rates up to several kHz.

Sliding Mode Control of DFIG Wind Turbines with a Fast Exponential Reaching Law

Directory of Open Access Journals (Sweden)

Linyun Xiong

2017-11-01

Full Text Available This paper proposes a novel sliding mode control (SMC technique for doubly fed induction generators (DFIGs based on the fast exponential reaching law (FERL. The proposed FERL-based SMC is capable of reducing to a large extent the chattering phenomena existing in the sliding stage. Meanwhile, the reaching stage is accelerated with the introduction of an adaptive gain. The proposed method is employed in a DFIG-based wind energy conversion system (WECS for direct power control (DPC. The FERL-based DPC approach is tested with simulations conducted in Matlab/Simulink under the scenarios of unbalanced grid voltage, grid fault conditions and highly unstable wind speed accompanied by an experimental study. The simulations and experimental results reveal the better performance of the proposed control method in active/reactive power tracking and dc-link voltage maintenance.

Maximum Power Point Tracking Based on Sliding Mode Control

Directory of Open Access Journals (Sweden)

Nimrod Vázquez

2015-01-01

Full Text Available Solar panels, which have become a good choice, are used to generate and supply electricity in commercial and residential applications. This generated power starts with the solar cells, which have a complex relationship between solar irradiation, temperature, and output power. For this reason a tracking of the maximum power point is required. Traditionally, this has been made by considering just current and voltage conditions at the photovoltaic panel; however, temperature also influences the process. In this paper the voltage, current, and temperature in the PV system are considered to be a part of a sliding surface for the proposed maximum power point tracking; this means a sliding mode controller is applied. Obtained results gave a good dynamic response, as a difference from traditional schemes, which are only based on computational algorithms. A traditional algorithm based on MPPT was added in order to assure a low steady state error.

Fault Modeling and Testing for Analog Circuits in Complex Space Based on Supply Current and Output Voltage

Directory of Open Access Journals (Sweden)

Hongzhi Hu

2015-01-01

Full Text Available This paper deals with the modeling of fault for analog circuits. A two-dimensional (2D fault model is first proposed based on collaborative analysis of supply current and output voltage. This model is a family of circle loci on the complex plane, and it simplifies greatly the algorithms for test point selection and potential fault simulations, which are primary difficulties in fault diagnosis of analog circuits. Furthermore, in order to reduce the difficulty of fault location, an improved fault model in three-dimensional (3D complex space is proposed, which achieves a far better fault detection ratio (FDR against measurement error and parametric tolerance. To address the problem of fault masking in both 2D and 3D fault models, this paper proposes an effective design for testability (DFT method. By adding redundant bypassing-components in the circuit under test (CUT, this method achieves excellent fault isolation ratio (FIR in ambiguity group isolation. The efficacy of the proposed model and testing method is validated through experimental results provided in this paper.

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.

Analog-to-digital conversion of spectrometric data in information-control systems of activation analysis

Energy Technology Data Exchange (ETDEWEB)

Mamonov, E I

1972-01-01

Analog-digital conversion (ADC) techniques in nuclear radiation spectrometer channels is a most important link of information control systems in activation analysis. For the development of the ADC of spectrometer channels logico-structural methods of increasing the capacity, procedures for boosting frequency modes and improving the accuracy are promising. Procedures are suggested for increasing the ADC capacity. Insufficient stability and noticeable non-linearity of the spectrometer channel can be corrected at the information processing stage if their regularities are known. Capacity limitations make the development of ADC featuring high stability, capacity and linearity quite urgent.

Electromagnetically induced transparency control in terahertz metasurfaces based on bright-bright mode coupling

Science.gov (United States)

Yahiaoui, R.; Burrow, J. A.; Mekonen, S. M.; Sarangan, A.; Mathews, J.; Agha, I.; Searles, T. A.

2018-04-01

We demonstrate a classical analog of electromagnetically induced transparency (EIT) in a highly flexible planar terahertz metamaterial (MM) comprised of three-gap split-ring resonators. The keys to achieve EIT in this system are the frequency detuning and hybridization processes between two bright modes coexisting in the same unit cell as opposed to bright-dark modes. We present experimental verification of two bright modes coupling for a terahertz EIT-MM in the context of numerical results and theoretical analysis based on a coupled Lorentz oscillator model. In addition, a hybrid variation of the EIT-MM is proposed and implemented numerically to dynamically tune the EIT window by incorporating photosensitive silicon pads in the split gap region of the resonators. As a result, this hybrid MM enables the active optical control of a transition from the on state (EIT mode) to the off state (dipole mode).

On Secondary Control Approaches for Voltage Regulation in DC Microgrids

DEFF Research Database (Denmark)

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

2017-01-01

Centralized or decentralized secondary controller is commonly 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...

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......, and then the system is more difficult to control. This paper proposed a DC-link control method for the two stages cascaded converter, and it uses proportional controller for the DC-link voltage control. This control method can achieve zero steady state error on the DC-link voltage; reduce the control system type...

Secondary control for voltage unbalance compensation in an islanded microgrid

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Guerrero, Josep M.; Jalilian, Alireza

2011-01-01

In this paper, the concept of secondary control is applied for voltage unbalance compensation in an islanded microgrid. The aim of the proposed control approach is to enhance the voltage quality at the point of common coupling (PCC). Unbalance compensation is achieved by proper control...... of distributed generators (DGs). The DGs control structure mainly consists of active and reactive power controllers, virtual impedance loop and voltage and current proportional-resonant controllers. Simulation results are presented for different cases. The results show the effectiveness of the proposed approach...

On Secondary Control Approaches for Voltage Regulation in DC Microgrids

DEFF Research Database (Denmark)

Peyghami, Saeed; Mokhtari, Hossein; Davari, Pooya

2017-01-01

Centralized or decentralized secondary controller is commonly 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 r...

Enhanced Voltage Control of VSC-HVDC Connected Offshore Wind Farms Based on Model Predictive Control

DEFF Research Database (Denmark)

Guo, Yifei; Gao, Houlei; Wu, Qiuwei

2018-01-01

This paper proposes an enhanced voltage control strategy (EVCS) based on model predictive control (MPC) for voltage source converter based high voltage direct current (VSCHVDC) connected offshore wind farms (OWFs). In the proposed MPC based EVCS, all wind turbine generators (WTGs) as well...... as the wind farm side VSC are optimally coordinated to keep voltages within the feasible range and reduce system power losses. Considering the high ratio of the OWF collector system, the effects of active power outputs of WTGs on voltage control are also taken into consideration. The predictive model of VSC...

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.

Autonomous Voltage Unbalance Compensation in an Islanded Droop-Controlled Microgrid

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Jalilian, Alireza; Vasquez, Juan Carlos

2013-01-01

Recently, there is an increasing interest in using distributed generators (DGs) not only to inject power into the grid, but also to enhance the power quality. In this paper, a stationary-frame control method for voltage unbalance compensation in an islanded microgrid is proposed. This method...... is based on the proper control of DGs interface converters. The DGs are controlled to compensate voltage unbalance autonomously while share the compensation effort and also active and reactive power, properly. The control system of the DGs mainly consists of active and reactive power droop controllers......, virtual impedance loop, voltage and current controllers and unbalance compensator. The design approach of the control system is discussed in detail and simulation and experimental results are presented. The results demonstrate the effectiveness of the proposed method in compensation of voltage unbalance....

DiSC: A Simulation Framework for Distribution System Voltage Control

DEFF Research Database (Denmark)

Pedersen, Rasmus; Sloth, Christoffer Eg; Andresen, Gorm

2015-01-01

This paper presents the MATLAB simulation framework, DiSC, for verifying voltage control approaches in power distribution systems. It consists of real consumption data, stochastic models of renewable resources, flexible assets, electrical grid, and models of the underlying communication channels....... The simulation framework makes it possible to validate control approaches, and thus advance realistic and robust control algorithms for distribution system voltage control. Two examples demonstrate the potential voltage issues from penetration of renewables in the distribution grid, along with simple control...

Control voltage and power fluctuations when connecting wind farms

Science.gov (United States)

Berinde, Ioan; Bǎlan, Horia; Oros Pop, Teodora Susana

2015-12-01

Voltage, frequency, active power and reactive power are very important parameters in terms of power quality. These parameters are followed when connecting any power plant, the more the connection of wind farms. Connecting wind farms to the electricity system must not cause interference outside the limits set by regulations. Modern solutions for fast and automatic voltage control and power fluctuations using electronic control systems of reactive power flows. FACTS (Flexible Alternating Current Transmision System) systems, established on the basis of power electronic circuits ensure control of electrical status quantities to achieve the necessary transfer of power to the power grid. FACTS devices can quickly control parameters and sizes of state power lines, such as impedance line voltages and phase angles of the voltages of the two ends of the line. Their use can lead to improvement in power system operation by increasing the transmission capacity of power lines, power flow control lines, improved static and transient stability reserve.

Control voltage and power fluctuations when connecting wind farms

International Nuclear Information System (INIS)

Berinde, Ioan; Bălan, Horia; Oros, Teodora Susana

2015-01-01

Voltage, frequency, active power and reactive power are very important parameters in terms of power quality. These parameters are followed when connecting any power plant, the more the connection of wind farms. Connecting wind farms to the electricity system must not cause interference outside the limits set by regulations. Modern solutions for fast and automatic voltage control and power fluctuations using electronic control systems of reactive power flows. FACTS (Flexible Alternating Current Transmision System) systems, established on the basis of power electronic circuits ensure control of electrical status quantities to achieve the necessary transfer of power to the power grid. FACTS devices can quickly control parameters and sizes of state power lines, such as impedance line voltages and phase angles of the voltages of the two ends of the line. Their use can lead to improvement in power system operation by increasing the transmission capacity of power lines, power flow control lines, improved static and transient stability reserve

Control voltage and power fluctuations when connecting wind farms

Energy Technology Data Exchange (ETDEWEB)

Berinde, Ioan, E-mail: ioan-berinde@yahoo.com; Bălan, Horia, E-mail: hbalan@mail.utcluj.ro; Oros, Teodora Susana, E-mail: teodoraoros-87@yahoo.com [Technical University of Cluj-Napoca, Romania, Faculty of Electrical Engineering, Department of Power Engineering and Management (Romania)

2015-12-23

Voltage, frequency, active power and reactive power are very important parameters in terms of power quality. These parameters are followed when connecting any power plant, the more the connection of wind farms. Connecting wind farms to the electricity system must not cause interference outside the limits set by regulations. Modern solutions for fast and automatic voltage control and power fluctuations using electronic control systems of reactive power flows. FACTS (Flexible Alternating Current Transmision System) systems, established on the basis of power electronic circuits ensure control of electrical status quantities to achieve the necessary transfer of power to the power grid. FACTS devices can quickly control parameters and sizes of state power lines, such as impedance line voltages and phase angles of the voltages of the two ends of the line. Their use can lead to improvement in power system operation by increasing the transmission capacity of power lines, power flow control lines, improved static and transient stability reserve.

Automatic Voltage Control (AVC) System under Uncertainty from Wind Power

DEFF Research Database (Denmark)

Qin, Nan; Abildgaard, Hans; Flynn, Damian

2016-01-01

An automatic voltage control (AVC) system maintains the voltage profile of a power system in an acceptable range and minimizes the operational cost by coordinating the regulation of controllable components. Typically, all of the parameters in the optimization problem are assumed to be certain...... and constant in the decision making process. However, for high shares of wind power, uncertainty in the decision process due to wind power variability may result in an infeasible AVC solution. This paper proposes a voltage control approach which considers the voltage uncertainty from wind power productions....... The proposed method improves the performance and the robustness of a scenario based approach by estimating the potential voltage variations due to fluctuating wind power production, and introduces a voltage margin to protect the decision against uncertainty for each scenario. The effectiveness of the proposed...

IBM-PC based high voltage controller [Paper No.: L7

International Nuclear Information System (INIS)

Mondal, N.K.; Kalmani, S.D.

1993-01-01

A simple IBM-PC/XT based high voltage controller is designed for C.A.E.N. high voltage supply unit, which is being used for testing the prototype detector for future accelerator experiment. The high voltage output of the supply unit can be remotely programmed. The V-set Lemo connectors at the rear panel provides the remote control facility. Similarly V-mon and I-mon can be used for remotely monitoring the voltage set and the current drawn from the supply unit. The controller described here sets the high voltage through V-set and monitors the voltage set, through V-mon at a pre-determined time interval. The monitoring is a background job and is done as an interrupt service routine of IRQ3. A simple menu driven software package used is written in Q-Basic and MASM. (author). 1 fig

Secondary Voltage Control for Harmonics Suppression in Islanded Microgrids

DEFF Research Database (Denmark)

Wang, Xiongfei; Guerrero, Josep M.; Blaabjerg, Frede

2011-01-01

in islanded microgrids. In addition to the centralized controller for fundamental frequency voltage component, a selective harmonic compensator is implemented in the secondary voltage control system. With the help of Park transformation, the cyclic references generated by the selective harmonic compensator...

30 CFR 77.515 - Bare signal or control wires; voltage.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Bare signal or control wires; voltage. 77.515 Section 77.515 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE... COAL MINES Electrical Equipment-General § 77.515 Bare signal or control wires; voltage. The voltage on...

An estimator-based distributed voltage-predictive control strategy for ac islanded microgrids

DEFF Research Database (Denmark)

Wang, Yanbo; Chen, Zhe; Wang, Xiongfei

2015-01-01

This paper presents an estimator-based voltage predictive control strategy for AC islanded microgrids, which is able to perform voltage control without any communication facilities. The proposed control strategy is composed of a network voltage estimator and a voltage predictive controller for each...... and has a good capability to reject uncertain perturbations of islanded microgrids....

Hierarchical Control Scheme for Voltage Harmonics Compensation in an Islanded Droop-Controlled Microgrid

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Guerrero, Josep M.; Jalilian, Alireza

2011-01-01

In this paper, a microgrid hierarchical control scheme is proposed which includes primary and secondary control levels. The primary level comprises distributed generators (DGs) local controllers. The local controller mainly consists of active and reactive power controllers, voltage and current...... controllers, and virtual impedance loop. A novel virtual impedance structure is proposed to achieve proper sharing of non-fundamental power among the microgrid DGs. The secondary level is designed to manage compensation of voltage harmonics at the microgrid load bus (LB) to which the sensitive loads may...... be connected. Also, restoration of LB voltage amplitude and microgrid frequency to the rated values is directed by the secondary level. These functions are achieved by sending proper control signals to the local controllers. The simulation results show the effectiveness of the proposed control scheme....

Unequal Input Voltages Distribution Between the Serial Connected Halfbridges

Directory of Open Access Journals (Sweden)

Radovan Ovcarcik

2006-01-01

Full Text Available This paper describes a topology of DC-DC converter consisting in two serial connected half-bridges. Secondary circuit is realized like a conventional full-wave rectifier. The main advantage of this topology is the possibility of dividing the input voltage between the half-bridges. The converter is controlled using the phase-shift modulation, which allows a ZVSoperation mode. The voltage unbalance between the inputs causes an important problem of the presented topology. It is necessary to avoid it by the control algorithm, which is described in the text. The practical results show a zero voltage switching technique and the limits of the chosen topology and of the control.

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...

Evaluation of Voltage Control Approaches for Future Smart Distribution Networks

Directory of Open Access Journals (Sweden)

Pengfei Wang

2017-08-01

Full Text Available This paper evaluates meta-heuristic and deterministic approaches for distribution network voltage control. As part of this evaluation, a novel meta-heuristic algorithm, Cuckoo Search, is applied for distribution network voltage control and compared with a deterministic voltage control algorithm, the oriented discrete coordinate decent method (ODCDM. ODCDM has been adopted in a state-of-the-art industrial product and applied in real distribution networks. These two algorithms have been evaluated under a set of test cases, which were generated to represent the voltage control problems in current and future distribution networks. Sampled test results have been presented, and findings have been discussed regarding the adoption of different optimization algorithms for current and future distribution networks.

Smart Demand for Improving Short-term Voltage Control on Distribution Networks

DEFF Research Database (Denmark)

Garcia-Valle, Rodrigo; P. Da Silva, Luiz C.; Xu, Zhao

2009-01-01

customer integration to aid power system performance is almost inevitable. This study introduces a new type of smart demand side technology, denoted demand as voltage controlled reserve (DVR), to improve short-term voltage control, where customers are expected to play a more dynamic role to improve voltage...... control. The technology can be provided by thermostatically controlled loads as well as other types of load. This technology is proven to be effective in case of distribution systems with a large composition of induction motors, where the voltage presents a slow recovery characteristic due to deceleration...... of the motors during faults. This study presents detailed models, discussion and simulation tests to demonstrate the technical viability and effectiveness of the DVR technology for short-term voltage control....

Investigation on the Development of a Sliding Mode Controller for Constant Power Loads in Microgrids

Directory of Open Access Journals (Sweden)

Eklas Hossain

2017-07-01

Full Text Available To implement renewable energy resources, microgrid systems have been adopted and developed into the technology of choice to assure mass electrification in the next decade. Microgrid systems have a number of advantages over conventional utility grid systems, however, they face severe instability issues due to the continually increasing constant power loads. To improve the stability of the entire system, the load side compensation technique is chosen because of its robustness and cost effectiveness. In this particular occasion, a sliding mode controller is developed for a microgrid system in the presence of constant power loads to assure a certain control objective of keeping the output voltage constant at 480 V. After that, a robustness analysis of the sliding mode controller against parametric uncertainties was performed and the sliding mode controller’s robustness against parametric uncertainties, frequency variations, and additive white Gaussian noise (AWGN are presented. Later, the performance of the proportional integral derivative (PID and sliding mode controller are compared in the case of nonlinearity, parameter uncertainties, and noise rejection to justify the selection of the sliding mode controller over the PID controller. All the necessary calculations are reckoned mathematically and results are verified in a virtual platform such as MATLAB/Simulink with a positive outcome.

Voltage control in smart grid using T2FLS

DEFF Research Database (Denmark)

Khodayar, Yaser; Sabahi, Kamel; Hajizadeh, Amin

2017-01-01

coordinated to keep the voltage within the standard range. Therefore, in this paper, a multi-agent controller based on type-2 fuzzy logic system (T2FLS) is utilized to coordinate the DG, ULTC, and load to regulate the voltage of the smart grid in the presence of noise and uncertainty. The proposed fuzzy...... system identifies the different parts of the smart grid as an agent (i.e. ULTC, DG, and load) and regulates the voltage by managing them. A 16-bus power system has been utilized to demonstrate the effectiveness of the proposed method. It has been shown that the proposed T2FLS controller outperforms...... the type-1 fuzzy controller and regulates the voltage in an appropriate way even in the presence of the different levels of measurement noise and uncertainty....

Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks

Science.gov (United States)

Pace, D. C.; Austin, M. E.; Bardoczi, L.; Collins, C. S.; Crowley, B.; Davis, E.; Du, X.; Ferron, J.; Grierson, B. A.; Heidbrink, W. W.; Holcomb, C. T.; McKee, G. R.; Pawley, C.; Petty, C. C.; Podestà, M.; Rauch, J.; Scoville, J. T.; Spong, D. A.; Thome, K. E.; Van Zeeland, M. A.; Varela, J.; Victor, B.

2018-05-01

An engineering upgrade to the neutral beam system at the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] enables time-dependent programming of the beam voltage and current. Initial application of this capability involves pre-programmed beam voltage and current injected into plasmas that are known to be susceptible to instabilities that are driven by energetic ( E ≥ 40 keV) beam ions. These instabilities, here all Alfvén eigenmodes (AEs), increase the transport of the beam ions beyond a classical expectation based on particle drifts and collisions. Injecting neutral beam power, P beam ≥ 2 MW, at reduced voltage with increased current reduces the drive for Alfvénic instabilities and results in improved ion confinement. In lower-confinement plasmas, this technique is applied to eliminate the presence of AEs across the mid-radius of the plasmas. Simulations of those plasmas indicate that the mode drive is decreased and the radial extent of the remaining modes is reduced compared to a higher beam voltage case. In higher-confinement plasmas, this technique reduces AE activity in the far edge and results in an interesting scenario of beam current drive improving as the beam voltage reduces from 80 kV to 65 kV.

Resistive RAMs as analog trimming elements

Science.gov (United States)

Aziza, H.; Perez, A.; Portal, J. M.

2018-04-01

This work investigates the use of Resistive Random Access Memory (RRAM) as an analog trimming device. The analog storage feature of the RRAM cell is evaluated and the ability of the RRAM to hold several resistance states is exploited to propose analog trim elements. To modulate the memory cell resistance, a series of short programming pulses are applied across the RRAM cell allowing a fine calibration of the RRAM resistance. The RRAM non volatility feature makes the analog device powers up already calibrated for the system in which the analog trimmed structure is embedded. To validate the concept, a test structure consisting of a voltage reference is evaluated.

Assessment of the operating conditions of coordinated Q-V controller within secondary voltage control system

Directory of Open Access Journals (Sweden)

Arnautović Dušan

2014-01-01

Full Text Available The paper, discusses the possibility to use coordinated Q-V controller (CQVC to perform secondary voltage control at the power plant level. The CQVC performs the coordination of the synchronous generators' (SG reactive power outputs in order to maintain the same total reactive power delivered by the steam power plant (SPP, while at the same time maintaining a constant voltage with programmed reactive droop characteristic at the SPP HV busbar. This busbar is the natural pilot node for secondary voltage control at HV level as the node with maximum power production and maximum power consumption. In addition to voltage control, the CQVC maintains the uniform allocation of reactive power reserves at all SGs in the power plant. This is accomplished by setting the reactive power of each SG at given operating point in accordance to the available reactive power of the same SG at that point. Different limitations imposed by unit's and plant equipment are superimposed on original SG operating chart (provided by the manufacturer in order to establish realistic limits of SG operation at given operating point. The CQVC facilitates: i practical implementation of secondary voltage control in power system, as it is capable of ensuring delivery of reactive power as requested by regional/voltage control while maintaining voltage at system pilot node, ii the full deployment of available reactive power of SGs which in turn contributes to system stability, iii assessment of the reactive power impact/contribution of each generator in providing voltage control as ancillary service. Furthermore, it is also possible to use CQVC to pricing reactive power production cost at each SG involved and to design reactive power bidding structure for transmission network devices by using recorded data. Practical exploitation experience acquired during CQVC continuous operation for over two years enabled implementation of the optimal setting of reference voltage and droop on daily

Application in low level counting of corona counters operating in voltage or current pulse recording modes

International Nuclear Information System (INIS)

Oravec, J.; Usacev, S.; Duka-Zojomi, A.; Sitar, B.; Benovic, D.; Holy, K.

1977-01-01

The advantages of current or voltage modes of recording are discussed. It appears that the current mode is more advantageous in measurements of rare events caused by highly ionizing particles on a high background of weakly ionizing particles. A 2.3 litre multiwire corona counter was used for the determination of 226 Ra content in drinking water. The 226 Ra content was estimated by measuring 222 Rn activity. The minimum measurable activity of the system was 0.07 pCi/l of water. (author)

Analysis of operating conditions of the voltage transformer

Directory of Open Access Journals (Sweden)

Fastiy G. P.

2017-12-01

Full Text Available In electrical networks, constant monitoring of the electrical equipment operation is necessary. To accomplish this task, current transformers and voltage transformers (VT are used, on which the accuracy of electrical measurements, electricity metering, and the reliability of the emergency control system depend. The results of the analysis of the conditions for forming the magnetization of a voltage transformer in the mode with unilateral connection of overhead transmission lines, as well as variants of violations in the 110 kV network that may exist for a relatively long time have been presented. It should be noted that the considered network has its own peculiarities: the overhead transmission lines connected in series have a significant length and a low level of load, which may be a condition for the appearance of a transmission lines capacitive effect (the Ferranti effect, the latter can cause overvoltage. Overvoltage occurs when the operating modes are temporary in terms of operation, adverse combinations of network parameters take place, and can continue until the circuit and network modes change. Most often they appear in asymmetric modes, with short circuits to ground, etc. Asymmetric modes caused by incomplete-phase commutations and wire breaks on the overhead line, as well as wire breaks with subsequent disconnection of power transformers that can affect the voltage level on the VT have been considered. The possibility of VT magnetizing with a prolonged voltage rise in symmetric modes, namely, the manifestation of the Ferranti effect with various loads at substations up to complete switching-off and power transformers switching off has been investigated. The analysis of the measuring voltage transformer operating conditions has been based on materials provided by the "Kolenergo" services.

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.

Voltage Control System of A DC Generator Using PLC

OpenAIRE

Subrata CHATTOPADHYAY; Sagarika PAL

2008-01-01

The voltage control system of a DC generator may suffer from high frequency oscillations without offset or low frequency oscillation with offset. A PID controller can eliminate both these errors. In the present paper, the voltage control system of a DC generator using a PLC based PID controller has been designed. Operation of PLC as a continuous controller has been described and the load characteristic of DC generator with and without controller have been determined experimentally and reporte...

The influence of the analog-to-digital conversion error on the JT-60 plasma position/shape feedback control system

International Nuclear Information System (INIS)

Yoshida, Michiharu; Kurihara, Kenichi

1995-12-01

In the plasma feedback control system (PFCS) and the direct digital controller (DDC) for the poloidal field coil power supply in the JT-60 tokamak, it is necessary to observe signals of all the poloidal field coil currents. Each of the signals, originally measured by a single sensor, is distributed to the PFCS and DDC through different cable routes and different analog-to-digital converters from each other. This produces the conversion error to the amount of several bits. Consequently, proper voltage from feedback calculation cannot be applied to the coil, and hence the control performance is possibly supposed to deteriorate to a certain extent. This paper describes how this error makes an influence on the plasma horizontal position control and how to improve the deteriorated control performance. (author)

A PASSIVELY MODE-LOCKED CR4+:FORSTERITE LASER WITH ELEСTRONICALLY CONTROLLED OUTPUT CHARACTERISTICS

Directory of Open Access Journals (Sweden)

S. A. Zolotovskaya

2011-01-01

Full Text Available Applicability of electronic control of laser output parameters to bulk solid-state laser sources is demonstrated. A single laser source with variable pulse duration for novel imaging and manipulation systems is presented. Stable passive mode-locking of a Cr4+:forsterite laser using a voltage controlled p-n junction quantum dot saturable absorber was achieved. Output shortening from 17,4 to 6,4 ps near-transform limited pulses was obtained by applying reverse bias.

Comparison of two voltage control strategies for a wind power plant

DEFF Research Database (Denmark)

Martinez, Jorge; Kjær, Philip C.; Rodriguez, Pedro

2011-01-01

plants. This paper addresses the analysis of two different voltage control strategies for a wind power plant, i.e. decentralized and centralized voltage control schemes. The analysis has been performed using the equivalent and simplified transfer functions of the system. Using this representation......Larger percentages of wind power penetration translate to more demanding requirements from grid codes. Recently, voltage support at the point of connection has been introduced by several grid codes from around the world, thus, making it important to analyze this control when applied to wind power......, it is possible to investigate the influence of the plant control gain, short circuit ratio, and time delays on the system stability, as well as the fulfillment of the design requirements. The implemented plant voltage control is based on a slope voltage controller, which calculates the references to be sent...

Modes in light wave propagating in semiconductor laser

Science.gov (United States)

Manko, Margarita A.

1994-01-01

The study of semiconductor laser based on an analogy of the Schrodinger equation and an equation describing light wave propagation in nonhomogeneous medium is developed. The active region of semiconductor laser is considered as optical waveguide confining the electromagnetic field in the cross-section (x,y) and allowing waveguide propagation along the laser resonator (z). The mode structure is investigated taking into account the transversal and what is the important part of the suggested consideration longitudinal nonhomogeneity of the optical waveguide. It is shown that the Gaussian modes in the case correspond to spatial squeezing and correlation. Spatially squeezed two-mode structure of nonhomogeneous optical waveguide is given explicitly. Distribution of light among the laser discrete modes is presented. Properties of the spatially squeezed two-mode field are described. The analog of Franck-Condon principle for finding the maxima of the distribution function and the analog of Ramsauer effect for control of spatial distribution of laser emission are discussed.

Programs for control of an analog-signal switching network

International Nuclear Information System (INIS)

D'Ottavio, T.; Enriquez, R.; Katz, R.; Skelly, J.

1989-01-01

A suite of programs has been developed to control the network of analog-signal switching multiplexers in the AGS complex. The software is driven by a relational database which describes the architecture of the multiplexer tree and the set of available analog signals. Signals are routed through a three-layer multiplexer tree, to be made available at four consoles each with three 4-trace oscilloscopes. A menu-structured operator interface program is available at each console, to accept requests to route any available analog signal to any of that console's 12 oscilloscope traces. A common routing-server program provides automatic routing-server program provides automatic routing of requested signals through the layers of multiplexers, maintaining a reservation database to denote free and in-use trunks. Expansion of the analog signal system is easily accommodated in software by adding new signals, trunks, multiplexers, or consoles to the database. Programmatic control of the triggering signals for each of the oscilloscopes is also provided. 3 refs., 4 figs., 3 tabs

Finite Control Set Model Predictive Control for Multiple Distributed Generators Microgrids

Science.gov (United States)

Babqi, Abdulrahman Jamal

This dissertation proposes two control strategies for AC microgrids that consist of multiple distributed generators (DGs). The control strategies are valid for both grid-connected and islanded modes of operation. In general, microgrid can operate as a stand-alone system (i.e., islanded mode) or while it is connected to the utility grid (i.e., grid connected mode). To enhance the performance of a micrgorid, a sophisticated control scheme should be employed. The control strategies of microgrids can be divided into primary and secondary controls. The primary control regulates the output active and reactive powers of each DG in grid-connected mode as well as the output voltage and frequency of each DG in islanded mode. The secondary control is responsible for regulating the microgrid voltage and frequency in the islanded mode. Moreover, it provides power sharing schemes among the DGs. In other words, the secondary control specifies the set points (i.e. reference values) for the primary controllers. In this dissertation, Finite Control Set Model Predictive Control (FCS-MPC) was proposed for controlling microgrids. FCS-MPC was used as the primary controller to regulate the output power of each DG (in the grid-connected mode) or the voltage of the point of DG coupling (in the islanded mode of operation). In the grid-connected mode, Direct Power Model Predictive Control (DPMPC) was implemented to manage the power flow between each DG and the utility grid. In the islanded mode, Voltage Model Predictive Control (VMPC), as the primary control, and droop control, as the secondary control, were employed to control the output voltage of each DG and system frequency. The controller was equipped with a supplementary current limiting technique in order to limit the output current of each DG in abnormal incidents. The control approach also enabled smooth transition between the two modes. The performance of the control strategy was investigated and verified using PSCAD/EMTDC software

Control of total voltage in the large distributed RF system of LEP

CERN Document Server

Ciapala, Edmond

1995-01-01

The LEP RF system is made up of a large number of independent RF units situated around the ring near the interaction points. These have different available RF voltages depending on their type and they may be inactive or unable to provide full voltage for certain periods. The original RF voltage control system was based on local RF unit voltage function generators pre-loaded with individual tables for energy ramping. This was replaced this year by a more flexible global RF voltage control system. A central controller in the main control room has direct access to the units over the LEP TDM system via multiplexers and local serial links. It continuously checks the state of all the units and adjusts their voltages to maintain the desired total voltage under all conditions. This voltage is distributed among the individual units to reduce the adverse effects of RF voltage asymmetry around the machine as far as possible. The central controller is a VME system with 68040 CPU and real time multitasking operating syste...

Phase modulation mode of scanning ion conductance microscopy

Energy Technology Data Exchange (ETDEWEB)

Li, Peng; Zhang, Changlin [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Lianqing, E-mail: lqliu@sia.cn, E-mail: gli@engr.pitt.edu; Wang, Yuechao; Yang, Yang [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Guangyong, E-mail: lqliu@sia.cn, E-mail: gli@engr.pitt.edu [Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261 (United States)

2014-08-04

This Letter reports a phase modulation (PM) mode of scanning ion conductance microscopy. In this mode, an AC current is directly generated by an AC voltage between the electrodes. The portion of the AC current in phase with the AC voltage, which is the current through the resistance path, is modulated by the tip-sample distance. It can be used as the input of feedback control to drive the scanner in Z direction. The PM mode, taking the advantages of both DC mode and traditional AC mode, is less prone to electronic noise and DC drift but maintains high scanning speed. The effectiveness of the PM mode has been proven by experiments.

A large dynamic range radiation-tolerant analog memory in a quarter- micron CMOS technology

CERN Document Server

Anelli, G; Rivetti, A

2001-01-01

An analog memory prototype containing 8*128 cells has been designed in a commercial quarter-micron CMOS process. The aim of this work is to investigate the possibility of designing large dynamic range mixed-mode switched capacitor circuits for high-energy physics (HEP) applications in deep submicron CMOS technologies. Special layout techniques have been used to make the circuit radiation tolerant. The memory cells employ gate-oxide capacitors for storage, permitting a very high density. A voltage write-voltage read architecture has been chosen to minimize the sensitivity to absolute capacitor values. The measured input voltage range is 2.3 V (the power supply voltage V/sub DD/ is equal to 2.5 V), with a linearity of almost 8 bits over 2 V. The dynamic range is more than 11 bits. The pedestal variation is +or-0.5 mV peak-to-peak. The noise measured, which is dominated by the noise of the measurement setup, is around 0.8 mV rms. The characteristics of the memory have been measured before irradiation and after 1...

Cable Insulation Breakdowns in the Modulator with a Switch Mode High Voltage Power Supply

CERN Document Server

Cours, A

2004-01-01

The Advanced Photon Source modulators are PFN-type pulsers with 40 kV switch mode charging power supplies (PSs). The PS and the PFN are connected to each other by 18 feet of high-voltage (HV) cable. Another HV cable connects two separate parts of the PFN. The cables are standard 75 kV x-ray cables. All four cable connectors were designed by the PS manufacturer. Both cables were operating at the same voltage level (about 35 kV). The PS’s output connector has never failed during five years of operation. One of the other three connectors failed approximately five times more often than the others. In order to resolve the failure problem, a transient analysis was performed for all connectors. It was found that transient voltage in the connector that failed most often was subjected to more high-frequency, high-amplitude AC components than the other three connectors. It was thought that these components caused partial discharge in the connector insulation and led to the insulation breakdown. Modification o...

Remote Supervision and Control of Air Conditioning Systems in Different Modes

Science.gov (United States)

Rafeeq, Mohammed; Afzal, Asif; Rajendra, Sree

2018-01-01

In the era of automation, most of the application of engineering and science are interrelated with system for optimal operation. To get the efficient result of an operation and desired response, interconnected systems should be controlled by directing, regulating and commanding. Here, air conditioning (AC) system is considered for experimentation, to supervise and control its functioning in both, automated and manual mode. This paper reports the work intended to design and develop an automated and manual AC system working in remote and local mode, to increase the level of comfort, easy operation, reducing human intervention and faults occurring in the system. The Programmable Logical Controller (PLC) and Supervisory Control and Data Acquisition (SCADA) system were used for remote supervision and monitoring of AC systems using series ninety protocol and remote terminal unit modbus protocol as communication module to operate in remote mode. PLC was used as remote terminal for continuous supervision and control of AC system. SCADA software was used as a tool for designing user friendly graphical user interface. The proposed SCADA AC system successfully monitors and controls in accordance within the parameter limits like temperature, pressure, humidity and voltage. With all the features, this designed system is capable of efficient handling of the resources like the compressor, humidifier etc., with all the levels of safety and durability. This system also maintains the temperature and controls the humidity of the remote location and also looks after the health of the compressor.

Development of a fast voltage control method for electrostatic accelerators

International Nuclear Information System (INIS)

Lobanov, Nikolai R.; Linardakis, Peter; Tsifakis, Dimitrios

2014-01-01

The concept of a novel fast voltage control loop for tandem electrostatic accelerators is described. This control loop utilises high-frequency components of the ion beam current intercepted by the image slits to generate a correction voltage that is applied to the first few gaps of the low- and high-energy acceleration tubes adjoining the high voltage terminal. New techniques for the direct measurement of the transfer function of an ultra-high impedance structure, such as an electrostatic accelerator, have been developed. For the first time, the transfer function for the fast feedback loop has been measured directly. Slow voltage variations are stabilised with common corona control loop and the relationship between transfer functions for the slow and new fast control loops required for optimum operation is discussed. The main source of terminal voltage instabilities, which are due to variation of the charging current caused by mechanical oscillations of charging chains, has been analysed

Voltage splay modes and enhanced phase locking in a modified linear Josephson array

International Nuclear Information System (INIS)

Harris, E.B.; Garland, J.C.

1997-01-01

We analyze a modified linear Josephson-junction array in which additional unbiased junctions are used to greatly enhance phase locking. This geometry exhibits strong correlated behavior, with an external magnetic field tuning the voltage splay angle between adjacent Josephson oscillators. The array displays a coherent in-phase mode for f=(1)/(2), where f is the magnetic frustration, while for 0 p (f)=2aV dc /Φ 0 (1-2f). The locked splay modes are found to be tolerant of critical current disorder approaching 100%. The stability of the array has also been studied by computing Floquet exponents. These exponents are found to be negative for all array lengths, with a 1/N 2 dependence, N being the number of series-connected junctions. copyright 1996 The American Physical Society

Quantum dynamics of a Josephson junction driven cavity mode system in the presence of voltage bias noise

Science.gov (United States)

Wang, Hui; Blencowe, M. P.; Armour, A. D.; Rimberg, A. J.

2017-09-01

We give a semiclassical analysis of the average photon number as well as photon number variance (Fano factor F ) for a Josephson junction (JJ) embedded microwave cavity system, where the JJ is subject to a fluctuating (i.e., noisy) bias voltage with finite dc average. Through the ac Josephson effect, the dc voltage bias drives the effectively nonlinear microwave cavity mode into an amplitude squeezed state (F Armour et al., Phys. Rev. Lett. 111, 247001 (2013), 10.1103/PhysRevLett.111.247001], but bias noise acts to degrade this squeezing. We find that the sensitivity of the Fano factor to bias voltage noise depends qualitatively on which stable fixed point regime the system is in for the corresponding classical nonlinear steady-state dynamics. Furthermore, we show that the impact of voltage bias noise is most significant when the cavity is excited to states with large average photon number.

Computer applications: Automatic control system for high-voltage accelerator

International Nuclear Information System (INIS)

Bryukhanov, A.N.; Komissarov, P.Yu.; Lapin, V.V.; Latushkin, S.T.. Fomenko, D.E.; Yudin, L.I.

1992-01-01

An automatic control system for a high-voltage electrostatic accelerator with an accelerating potential of up to 500 kV is described. The electronic apparatus on the high-voltage platform is controlled and monitored by means of a fiber-optic data-exchange system. The system is based on CAMAC modules that are controlled by a microprocessor crate controller. Data on accelerator operation are represented and control instructions are issued by means of an alphanumeric terminal. 8 refs., 6 figs

On-line control system for electron injector based on autoemission cathode

International Nuclear Information System (INIS)

Egorov, N.V.; Karpov, A.G.; Ovsyannikov, D.A.; Prudnikov, A.P.

1987-01-01

An original on-line system of control of electron injector parameters on the base of an autoemission cathode is described. The system includes hardware (analog-to-digital and graphical displays, a printer, a magnetic disc memory a plotter) and data control and readout equipment. A high-voltage power source of the 'RACE' is controlled by digital measuring devices connected with a computer data via a special matching device. Software includes servicing subroutines for injector controls and those permitting to display, plot and print results. The main operating program functioning in the interactive mode enables to specify the injector operating conditions and check its characteristics

Reynolds analogy for the Rayleigh problem at various flow modes.

Science.gov (United States)

Abramov, A A; Butkovskii, A V

2016-07-01

The Reynolds analogy and the extended Reynolds analogy for the Rayleigh problem are considered. For a viscous incompressible fluid we derive the Reynolds analogy as a function of the Prandtl number and the Eckert number. We show that for any positive Eckert number, the Reynolds analogy as a function of the Prandtl number has a maximum. For a monatomic gas in the transitional flow regime, using the direct simulation Monte Carlo method, we investigate the extended Reynolds analogy, i.e., the relation between the shear stress and the energy flux transferred to the boundary surface, at different velocities and temperatures. We find that the extended Reynolds analogy for a rarefied monatomic gas flow with the temperature of the undisturbed gas equal to the surface temperature depends weakly on time and is close to 0.5. We show that at any fixed dimensionless time the extended Reynolds analogy depends on the plate velocity and temperature and undisturbed gas temperature mainly via the Eckert number. For Eckert numbers of the order of unity or less we generalize an extended Reynolds analogy. The generalized Reynolds analogy depends mainly only on dimensionless time for all considered Eckert numbers of the order of unity or less.

Modeling and Analysis of the Common Mode Voltage in a Cascaded H-Bridge Electronic Power Transformer

Directory of Open Access Journals (Sweden)

Yun Yang

2017-09-01

Full Text Available Electronic power transformers (EPTs have been identified as emerging intelligent electronic devices in the future smart grid, e.g., the Energy Internet, especially in the application of renewable energy conversion and management. Considering that the EPT is directly connected to the medium-voltage grid, e.g., a10 kV distribution system, and its cascaded H-bridges structure, the common mode voltage (CMV issue will be more complex and severe. The CMV will threaten the insulation of the entire EPT device and even produce common mode current. This paper investigates the generated mechanism and characteristics of the CMV in a cascaded H-bridge EPT (CHB-EPT under both balanced and fault grid conditions. First, the CHB-EPT system is introduced. Then, a three-phase simplified circuit model of the high-voltage side of the EPT system is presented. Combined with a unipolar modulation strategy and carrier phase shifting technology by rigorous mathematical analysis and derivation, the EPT internal CMV and its characteristics are obtained. Moreover, the influence of the sinusoidal pulse width modulation dead time is considered and discussed based on analytical calculation. Finally, the simulation results are provided to verify the validity of the aforementioned model and the analysis results. The proposed theoretical analysis method is also suitable for other similar cascaded converters and can provide a useful theoretical guide for structural design and power density optimization.

Generic inertia emulation controller for multi-terminal voltage-source-converter high voltage direct current systems

DEFF Research Database (Denmark)

Zhu, Jiebei; Guerrero, Josep M.; Hung, William

2014-01-01

A generic Inertia Emulation Controller (INEC) scheme for Multi-Terminal Voltage-Source-Converter based HVDC (VSC-MTDC) systems is proposed and presented in this paper. The proposed INEC can be incorporated in any Grid-side Voltage-Source-Converter (GVSC) station, allowing the MTDC terminal...

Electrical model of dielectric barrier discharge homogenous and filamentary modes

Science.gov (United States)

López-Fernandez, J. A.; Peña-Eguiluz, R.; López-Callejas, R.; Mercado-Cabrera, A.; Valencia-Alvarado, R.; Muñoz-Castro, A.; Rodríguez-Méndez, B. G.

2017-01-01

This work proposes an electrical model that combines homogeneous and filamentary modes of an atmospheric pressure dielectric barrier discharge cell. A voltage controlled electric current source has been utilized to implement the power law equation that represents the homogeneous discharge mode, which starts when the gas breakdown voltage is reached. The filamentary mode implies the emergence of electric current conducting channels (microdischarges), to add this phenomenon an RC circuit commutated by an ideal switch has been proposed. The switch activation occurs at a higher voltage level than the gas breakdown voltage because it is necessary to impose a huge electric field that contributes to the appearance of streamers. The model allows the estimation of several electric parameters inside the reactor that cannot be measured. Also, it is possible to appreciate the modes of the DBD depending on the applied voltage magnitude. Finally, it has been recognized a good agreement between simulation outcomes and experimental results.

Electrical model of dielectric barrier discharge homogenous and filamentary modes

International Nuclear Information System (INIS)

López-Fernandez, J A; Peña-Eguiluz, R; López-Callejas, R; Mercado-Cabrera, A; Valencia-Alvarado, R; Muñoz-Castro, A; Rodríguez-Méndez, B G

2017-01-01

This work proposes an electrical model that combines homogeneous and filamentary modes of an atmospheric pressure dielectric barrier discharge cell. A voltage controlled electric current source has been utilized to implement the power law equation that represents the homogeneous discharge mode, which starts when the gas breakdown voltage is reached. The filamentary mode implies the emergence of electric current conducting channels (microdischarges), to add this phenomenon an RC circuit commutated by an ideal switch has been proposed. The switch activation occurs at a higher voltage level than the gas breakdown voltage because it is necessary to impose a huge electric field that contributes to the appearance of streamers. The model allows the estimation of several electric parameters inside the reactor that cannot be measured. Also, it is possible to appreciate the modes of the DBD depending on the applied voltage magnitude. Finally, it has been recognized a good agreement between simulation outcomes and experimental results. (paper)

Global voltage control for the LEP RF system

International Nuclear Information System (INIS)

Ciapala, E.; Butterworth, A.; Peschardt, E.

1993-01-01

The LEG RF system is installed as independent 16 cavity units. In addition to the eight copper cavity units originally installed 12 units with super-conducting cavities are being added for the LEP200 energy upgrade. The total RF voltage determines the synchrotron tune (Qs) and must be controlled precisely during energy ramping. Local function generators in each of the RF units are pre-loaded such that when triggered simultaneously by ramp timing events transmitted over the general timing system the total voltage varies to give the Qs function required. A disadvantage is that loss of RF in a unit at any time after the loading process cannot be corrected. As the number of RF units increases automatic control of the total RF voltage and its distribution around LEP becomes desirable. A global voltage control system, based on a central VME controller, has recently been installed. It has direct and rapid access to the RF units over the LEP time division multiplexing system. Initial tests on operation and performance at fixed energy and during energy ramping are described, as well as the implementation of a Qs loop in which Qs can be set directly using on-line synchrotron frequency measurements

Voltage Control System of A DC Generator Using PLC

Directory of Open Access Journals (Sweden)

Subrata CHATTOPADHYAY

2008-06-01

Full Text Available The voltage control system of a DC generator may suffer from high frequency oscillations without offset or low frequency oscillation with offset. A PID controller can eliminate both these errors. In the present paper, the voltage control system of a DC generator using a PLC based PID controller has been designed. Operation of PLC as a continuous controller has been described and the load characteristic of DC generator with and without controller have been determined experimentally and reported in this paper.

DC Voltage Control and Power-Sharing of Multi-Terminal DC Grids Based on Optimal DC Power Flow and Flexible Voltage Droop Strategy

Directory of Open Access Journals (Sweden)

F. Azma

2015-06-01

Full Text Available This paper develops an effective control framework for DC voltage control and power-sharing of multi-terminal DC (MTDC grids based on an optimal power flow (OPF procedure and the voltage-droop control. In the proposed approach, an OPF algorithm is executed at the secondary level to find optimal reference of DC voltages and active powers of all voltage-regulating converters. Then, the voltage droop characteristics of voltage-regulating converters, at the primary level, are tuned based on the OPF results such that the operating point of the MTDC grid lies on the voltage droop characteristics. Consequently, the optimally-tuned voltage droop controller leads to the optimal operation of the MTDC grid. In case of variation in load or generation of the grid, a new stable operating point is achieved based on the voltage droop characteristics. By execution of a new OPF, the voltage droop characteristics are re-tuned for optimal operation of the MTDC grid after the occurrence of the load or generation variations. The results of simulation on a grid inspired by CIGRE B4 DC grid test system demonstrate efficient grid performance under the proposed control strategy.

Control analysis and experimental verification of a practical dc–dc boost converter

Directory of Open Access Journals (Sweden)

Saswati Swapna Dash

2015-12-01

Full Text Available This paper presents detailed open loop and closed loop analysis on boost dc–dc converter for both voltage mode control and current mode control. Here the boost dc–dc converter is a practical converter considering all possible parasitic elements like ESR and on state voltage drops. The open loop control, closed loop current mode control and voltage mode control are verified. The comparative study of all control techniques is presented. The PI compensator for closed loop current mode control is designed using these classical techniques like root locus technique and bode diagram. The simulation results are validated with the experimental results of voltage mode control for both open loop and closed loop control.

Feedforward Synchronised PWM for Adjustable Speed AC Drives with Different Control Modes

DEFF Research Database (Denmark)

Oleschuk, Valentin; Blaabjerg, Frede; Jensen, Flemming Buus

2002-01-01

This paper presents a novel method of direct synchronised pulswidth modulation (PWM) for three-phase voltage source inverters, feeding induction motors with different control regimes. It is based on the universal algorithm with either simplified algebraic or accurate trigonometric control functions......, with vector approached for determination of the pulse patterns, with vector approach for determination of the pulse patterns. Different control modes of the drive system with synchronised PWM, including standard scalar V/F control, and also V2/F = constant and V/F2 = constant control regimes, have been...... analysed in the paper. Simulations give the behaviour of the PWM techniques proposed. Both continuous and discontinuous schemes of synchronised PWM, applied for the corresponding control regime, have been analysed and compared....

Temperature Stabilized Characterization of High Voltage Power Supplies

CERN Document Server

Krarup, Ole

2017-01-01

High precision measurements of the masses of nuclear ions in the ISOLTRAP experiment relies on an MR-ToF. A major source of noise and drift is the instability of the high voltage power supplies employed. Electrical noise and temperature changes can broaden peaks in time-of-flight spectra and shift the position of peaks between runs. In this report we investigate how the noise and drift of high-voltage power supplies can be characterized. Results indicate that analog power supplies generally have better relative stability than digitally controlled ones, and that the high temperature coefficients of all power supplies merit efforts to stabilize them.

Reproducible and controllable induction voltage adder for scaled beam experiments

Energy Technology Data Exchange (ETDEWEB)

Sakai, Yasuo; Nakajima, Mitsuo; Horioka, Kazuhiko [Department of Energy Sciences, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)

2016-08-15

A reproducible and controllable induction adder was developed using solid-state switching devices and Finemet cores for scaled beam compression experiments. A gate controlled MOSFET circuit was developed for the controllable voltage driver. The MOSFET circuit drove the induction adder at low magnetization levels of the cores which enabled us to form reproducible modulation voltages with jitter less than 0.3 ns. Preliminary beam compression experiments indicated that the induction adder can improve the reproducibility of modulation voltages and advance the beam physics experiments.

Reduced Voltage Scaling in Clock Distribution Networks

Directory of Open Access Journals (Sweden)

Khader Mohammad

2009-01-01

Full Text Available We propose a novel circuit technique to generate a reduced voltage swing (RVS signals for active power reduction on main buses and clocks. This is achieved without performance degradation, without extra power supply requirement, and with minimum area overhead. The technique stops the discharge path on the net that is swinging low at a certain voltage value. It reduces active power on the target net by as much as 33% compared to traditional full swing signaling. The logic 0 voltage value is programmable through control bits. If desired, the reduced-swing mode can also be disabled. The approach assumes that the logic 0 voltage value is always less than the threshold voltage of the nMOS receivers, which eliminate the need of the low to high voltage translation. The reduced noise margin and the increased leakage on the receiver transistors using this approach have been addressed through the selective usage of multithreshold voltage (MTV devices and the programmability of the low voltage value.

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.

A microcontroller application as X-ray machine's high voltage controller

International Nuclear Information System (INIS)

Wiranto Budi Santoso; Beny Syawaludin

2010-01-01

A micro controller application as x-ray machine's high voltage controller has been carried out. The purpose of this micro controller application is to give an accurate high voltage supply to the x-ray tube so that the x-ray machine could produce the result as expected. The micro controller based X-ray machine's high voltage controller receives an input voltage from the keypad. This input value is displayed in the LCD (Liquid Crystal Display) screen. Then micro controller uses this input data to drive a stepper motor. The stepper motor adjusts the high voltage auto transformer's output according to the input value. The micro controller is programmed using BASCOM-8051 compiler. The test results show that the stepper motor could rotate according to an input value (author)

Troubleshooting analog circuits

CERN Document Server

Pease, Robert A

1991-01-01

Troubleshooting Analog Circuits is a guidebook for solving product or process related problems in analog circuits. The book also provides advice in selecting equipment, preventing problems, and general tips. The coverage of the book includes the philosophy of troubleshooting; the modes of failure of various components; and preventive measures. The text also deals with the active components of analog circuits, including diodes and rectifiers, optically coupled devices, solar cells, and batteries. The book will be of great use to both students and practitioners of electronics engineering. Other

Unbalanced voltage control of virtual synchronous generator in isolated micro-grid

Science.gov (United States)

Cao, Y. Z.; Wang, H. N.; Chen, B.

2017-06-01

Virtual synchronous generator (VSG) control is recommended to stabilize the voltage and frequency in isolated micro-grid. However, common VSG control is challenged by widely used unbalance loads, and the linked unbalance voltage problem worsens the power quality of the micro-grid. In this paper, the mathematical model of VSG was presented. Based on the analysis of positive- and negative-sequence equivalent circuit of VSG, an approach was proposed to eliminate the negative-sequence voltage of VSG with unbalance loads. Delay cancellation method and PI controller were utilized to identify and suppress the negative-sequence voltages. Simulation results verify the feasibility of proposed control strategy.

Scorpion β-toxin interference with NaV channel voltage sensor gives rise to excitatory and depressant modes

Science.gov (United States)

Leipold, Enrico; Borges, Adolfo

2012-01-01

Scorpion β toxins, peptides of ∼70 residues, specifically target voltage-gated sodium (NaV) channels to cause use-dependent subthreshold channel openings via a voltage–sensor trapping mechanism. This excitatory action is often overlaid by a not yet understood depressant mode in which NaV channel activity is inhibited. Here, we analyzed these two modes of gating modification by β-toxin Tz1 from Tityus zulianus on heterologously expressed NaV1.4 and NaV1.5 channels using the whole cell patch-clamp method. Tz1 facilitated the opening of NaV1.4 in a use-dependent manner and inhibited channel opening with a reversed use dependence. In contrast, the opening of NaV1.5 was exclusively inhibited without noticeable use dependence. Using chimeras of NaV1.4 and NaV1.5 channels, we demonstrated that gating modification by Tz1 depends on the specific structure of the voltage sensor in domain 2. Although residue G658 in NaV1.4 promotes the use-dependent transitions between Tz1 modification phenotypes, the equivalent residue in NaV1.5, N803, abolishes them. Gating charge neutralizations in the NaV1.4 domain 2 voltage sensor identified arginine residues at positions 663 and 669 as crucial for the outward and inward movement of this sensor, respectively. Our data support a model in which Tz1 can stabilize two conformations of the domain 2 voltage sensor: a preactivated outward position leading to NaV channels that open at subthreshold potentials, and a deactivated inward position preventing channels from opening. The results are best explained by a two-state voltage–sensor trapping model in that bound scorpion β toxin slows the activation as well as the deactivation kinetics of the voltage sensor in domain 2. PMID:22450487

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......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...... in a fast current regulation performance. Injection of zero voltage also minimizes the inverter voltage error effects caused by the dead-time....

A Communication-Less Distributed Voltage Control Strategy for a Multi-Bus AC Islanded Microgrid

DEFF Research Database (Denmark)

Wang, Yanbo; Tan, Yongdong; Chen, Zhe

2014-01-01

This paper presents a communication-less distributed voltage control strategy for a multi-bus AC islanded microgrid. First, a Kalman Filter-based network voltage estimator is proposed to obtain voltage responses without communication links in the presence of load disturbances. Then, a voltage...... and reliability is improved for islanded microgrids due to communication-less operation. The simulations and experimental results are presented to validate the proposed distributed voltage control strategy....... optimal controller using MPC (Model Predictive Control) are developed to implement voltage optimal control. The contributions of this paper are demonstrated: (1) The proposed voltage estimator can dynamically obtain network voltage responses just through local voltage and current associated with each DG...

Enhancement of micro-grid performance during islanding mode using storage batteries and new fuzzy logic pitch angle controller

International Nuclear Information System (INIS)

Kamel, Rashad M.; Chaouachi, A.; Nagasaka, Ken

2011-01-01

Research highlights: → Novel fuzzy pitch angle controller is proposed for smoothing wind fluctuation. → Storage batteries are used for performance improve of MG in islanding mode. → Those new techniques are compared with conventional PI pitch angle controller. -- Abstract: Power system deregulation, shortage of transmission capacities and needing to reduce green house gas have led to increase interesting in distributed generations (DGs) especially renewable sources. This study developed a complete model able to analysis and simulates in details the transient dynamic performance of the Micro-Grid (MG) during and subsequent islanding process. Wind speed fluctuations cause high fluctuations in output power of wind turbine which lead to fluctuations of frequency and voltages of the MG during the islanding mode. In this paper a new fuzzy logic pitch angle controller is proposed to smooth the output power of wind turbine to reduce MG frequency and voltage fluctuations during the islanding mode. The proposed fuzzy logic pitch controller is compared with the conventional PI pitch angle controller which usually used for wind turbine power control. Results proved the effectiveness of the proposed fuzzy controller in improvement of the MG performance. Also, this paper proposed using storage batteries technique to reduce the frequency deviation and fluctuations originated from wind power solar power fluctuations. Results indicate that the storage batteries technique is superior than fuzzy logic pitch controller in reducing frequency deviation, but with more expensive than the fuzzy controller. All models and controllers are built using Matlab (registered) Simulink (registered) environment.

DFIG turbine representation for small signal voltage control studies

DEFF Research Database (Denmark)

Garcia, Jorge Martinez; Kjær, Philip Carne; Teodorescu, Remus

2010-01-01

This paper addresses the representation of a wind power plant, based on wound rotor asynchronous generators, with a centralized voltage controller, by an equivalent transfer function, valid for small signal voltage control studies. This representation allows to investigate the influence...... introduced recently by several grid codes from around the world, making important to analyze this control when applied to wind power plants. The performance of the equivalent transfer function has been evaluated and compared using an equivalent grid with different short circuit ratios and active power...... of the centralized plant control gain and short circuit ratio on the system stability, for instance, by analyzing the zero-pole placement. Larger percentages of wind power penetration translate to more demanding requirements coming from the grid codes, for example voltage support at the point of connection has been...

Direct Flux Control for Stand-Alone Operation Brushless Doubly Fed Induction Generators Using a Resonant-Based Sliding-Mode Control Approach

Directory of Open Access Journals (Sweden)

Kai Ji

2018-04-01

Full Text Available In this paper, a novel voltage control strategy for stand-alone operation brushless doubly fed induction generators for variable speed constant frequency wind energy conversion systems was presented and discussed. Based on the model of the power generation system, the proposed direct flux control strategy employs a nonlinear reduced-order generalized integrator-based resonant sliding-mode control approach to directly calculate and regulate the output value of converter which the control winding stator requires so as to eliminate its instantaneous errors, without involving any synchronous rotating coordinate transformations. The stability, robustness and convergence capability of the proposed control strategy were described and analyzed. Owing to the fact no additional current control inner loops are involved, the system configuration is therefore simplified and the dynamic performance enhanced. A constant converter switching frequency was achieved by using space vector pulse width modulation, which reduces the harmonics of the generator terminal voltage. In addition, the feasibility and validity of the proposed scheme is verified by experiments, and excellent steady and transient performance is achieved.

Modular Hybrid Energy Concept Employing a Novel Control Structure Based on a Simple Analog System

Directory of Open Access Journals (Sweden)

PETREUS, D.

2016-05-01

Full Text Available This paper proposes a novel control topology which enables the setup of a low cost analog system leading to the implementation of a modular energy conversion system. The modular concept is based on hybrid renewable energy (solar and wind and uses high voltage inverters already available on the market. An important feature of the proposed topology is a permanently active current loop, which assures short circuit protection and simplifies the control loops compensation. The innovative analogue solution of the control structure is based on a dedicated integrated circuit (IC for power factor correction (PFC circuits, used in a new configuration, to assure an efficient inverter start-up. The energy conversion system (control structure and maximum power point tracking algorithm is simulated using a new macromodel-based concept, which reduces the usual computational burden of the simulator and achieves high processing speed. The proposed novel system is presented in this article from concept, through the design and implementation stages, is verified through simulation and is validated by experimental results.

Feedback control of acoustic musical instruments: collocated control using physical analogs.

Science.gov (United States)

Berdahl, Edgar; Smith, Julius O; Niemeyer, Günter

2012-01-01

Traditionally, the average professional musician has owned numerous acoustic musical instruments, many of them having distinctive acoustic qualities. However, a modern musician could prefer to have a single musical instrument whose acoustics are programmable by feedback control, where acoustic variables are estimated from sensor measurements in real time and then fed back in order to influence the controlled variables. In this paper, theory is presented that describes stable feedback control of an acoustic musical instrument. The presentation should be accessible to members of the musical acoustics community who may have limited or no experience with feedback control. First, the only control strategy guaranteed to be stable subject to any musical instrument mobility is described: the sensors and actuators must be collocated, and the controller must emulate a physical analog system. Next, the most fundamental feedback controllers and the corresponding physical analog systems are presented. The effects that these controllers have on acoustic musical instruments are described. Finally, practical design challenges are discussed. A proof explains why changing the resonance frequency of a musical resonance requires much more control power than changing the decay time of the resonance. © 2012 Acoustical Society of America.

Design and Analysis of a Slope Voltage Control for a DFIG Wind Power Plant

DEFF Research Database (Denmark)

Martínez, J.; Kjær, P. C.; Rodriguez, Pedro

2012-01-01

This paper addresses a detailed design of a wind power plant and turbine slope voltage control in the presence of communication delays for a wide short-circuit ratio range operation. The implemented voltage control scheme is based upon the secondary voltage control concept, which offers fast...... of connection with the grid. The performance has been tested using PSCAD/EMTDC program. The plant layout used in the simulations is based on an installed wind power plant, composed of 23 doubly fed generator wind turbines. The resulting performance is evaluated using a compilation of grid code voltage control...... response to grid disturbances, despite the communication delays, i.e., this concept is based on a primary voltage control, located in the wind turbine, which follows an external voltage reference sent by a central controller, called secondary voltage control, which is controlling the voltage at the point...

A New Approach to HVDC Grid Voltage Control Based on Generalized State Feedback

DEFF Research Database (Denmark)

Beerten, Jef; Eriksson, Robert; Van Hertem, Dirk

2014-01-01

in the system hamper a straight-forward definition of the power sharing. The use of a common DC voltage signal for the control can solve some of the problems. However, it disregards some of the benefits that are associated with the use of a local voltage control, such as the tendency of a controller using local...... by combining the local voltage signal available at the converter terminals with remote voltage signals at different locations in the DC system by means of communication. The local voltage feedback control is used for a fast, reliable system response. The introduction of the remote voltage signals...... in the control allows to differentiate the system response for different converter outages. Simulation results show the validity of the proposed control scheme....

Sensorless Vector Control of AC Induction Motor Using Sliding-Mode Observer

Directory of Open Access Journals (Sweden)

Phuc Thinh Doan

2013-06-01

Full Text Available This paper develops a sensorless vector controlled method for AC induction motor using sliding-mode observer. For developing the control algorithm, modeling of AC induction motor is presented. After that, a sliding mode observer is proposed to estimate the motor speed, the rotor flux, the angular position of the rotor flux and the motor torque from monitored stator voltages and currents. The use of the nonlinear sliding mode observer provides very good performance for both low and high speed motor operation. Furthermore, the proposed system is robust in motor losses and load variations. The convergence of the proposed observer is obtained using the Lyapunov theory. Hardware and software for simulation and experiment of the AC induction motor drive are introduced. The hardware consists of a 1.5kw AC induction motor connected in series with a torque sensor and a powder brake. A controller is developed based on DSP TMS320F28355. The simulation and experimental results illustrate that fast torque and speed response with small torque ripples can be achieved. The proposed control scheme is suitable to the application fields that require high performance of torque response such as electric vehicles. doi:http://dx.doi.org/10.12777/ijse.4.2.2013.39-43 [How to cite this article: Doan, P. T., Nguyen, T. T., Jeong, S. K., Oh, S. J., & Kim, S. B. (2013. Sensorless Vector Control of AC Induction Motor Using Sliding-Mode Observer. INTERNATIONAL JOURNAL OF SCIENCE AND ENGINEERING, 4(2, 39-43; doi: http://dx.doi.org/10.12777/ijse.4.2.2013.39-43

Switched-capacitor multiply-by-two amplifier with reduced capacitor mismatches sensitivity and full swing sample signal common-mode voltage

International Nuclear Information System (INIS)

Xu Xinnan; Yao Suying; Xu Jiangtao; Nie Kaiming

2012-01-01

A switched-capacitor amplifier with an accurate gain of two that is insensitive to component mismatch is proposed. This structure is based on associating two sets of two capacitors in cross series during the amplification phase. This circuit permits the common-mode voltage of the sample signal to reach full swing. Using the charge-complement technique, the proposed amplifier can reduce the impact of parasitic capacitors on the gain accuracy effectively. Simulation results show that as sample signal common-mode voltage changes, the difference between the minimum and maximum gain error is less than 0.03%. When the capacitor mismatch is increased from 0 to 0.2%, the gain error is deteriorated by 0.00015%. In all simulations, the gain of amplifier is 69 dB. (semiconductor integrated circuits)

Characterization of a pulsed mode high voltage power supply for nuclear detectors

International Nuclear Information System (INIS)

Ghazali, A B; Ahmad, T S; Abdullah, N A

2013-01-01

This paper discusses the characterization of a pulsed mode high voltage power supply (HVPS) using LT1073 chip. The pulsed modulated signal generated from this chip is amplified using a step-up ferrite core transformer of 1:20 turn ratio and then further multiplied and converted into DC high voltage output using a diode-capacitor arrangement. The circuit is powered by a 9V alkaline battery but regulated at 5V supply. It was found that the output for this setup is 520V, 87 μA with 10% load regulation. This output is suitable to operate a pancake-type GM detector, typically model LND 7317 where the plateau is from 475V to 675V. It was also found that when a β-source with intensity of 120 cps is used, the power consumption of the circuit is 5 V, 10.1 mA only. When the battery was left 'on' for 40 hours continuously, the battery's voltage has dropped to 6.9V, meaning that the 5V supply as well as 520V output is still maintained. It is noted that the minimum output voltage of 475V has reached when the regulated supply has reduced to 4.6V and consequently the 9V battery dropped to 6.5V, and this had happened after approximately 3 days of continuous operation. The power efficiency for this circuitry was found to be 89.5%. This result has far better in performance since the commercial portable equipment of this type has normally specified that not less than 8 hours continuous operation only. On the circuit design for this power supply, it was found that the enveloped frequency is 133 Hz with approximately 50% duty cycle. The modulated frequency during 'on' state was found to be 256 KHz in which the majority of power consumption is required.

Low-sensitivity, low-bounce, high-linearity current-controlled oscillator suitable for single-supply mixed-mode instrumentation system.

Science.gov (United States)

Hwang, Yuh-Shyan; Kung, Che-Min; Lin, Ho-Cheng; Chen, Jiann-Jong

2009-02-01

A low-sensitivity, low-bounce, high-linearity current-controlled oscillator (CCO) suitable for a single-supply mixed-mode instrumentation system is designed and proposed in this paper. The designed CCO can be operated at low voltage (2 V). The power bounce and ground bounce generated by this CCO is less than 7 mVpp when the power-line parasitic inductance is increased to 100 nH to demonstrate the effect of power bounce and ground bounce. The power supply noise caused by the proposed CCO is less than 0.35% in reference to the 2 V supply voltage. The average conversion ratio KCCO is equal to 123.5 GHz/A. The linearity of conversion ratio is high and its tolerance is within +/-1.2%. The sensitivity of the proposed CCO is nearly independent of the power supply voltage, which is less than a conventional current-starved oscillator. The performance of the proposed CCO has been compared with the current-starved oscillator. It is shown that the proposed CCO is suitable for single-supply mixed-mode instrumentation systems.

Autonomous Operation of Low Voltage Microgrids

Directory of Open Access Journals (Sweden)

Irena Wasiak

2014-12-01

Full Text Available The article describes the possibilities of LV microgrids operation in the island mode. Control strategies of energy sources connected to the grid by means of invertors are discussed, either for a microgrid connected to the supplying network or during the island mode operation. The presented results of research were conducted at the Laboratory of Distributed Generation at Lodz University of Technology. The study was performed for two variants of reference voltage source: the battery storage and microturbine respectively.

RTDS implementation of an improved sliding mode based inverter controller for PV system.

Science.gov (United States)

Islam, Gazi; Muyeen, S M; Al-Durra, Ahmed; Hasanien, Hany M

2016-05-01

This paper proposes a novel approach for testing dynamics and control aspects of a large scale photovoltaic (PV) system in real time along with resolving design hindrances of controller parameters using Real Time Digital Simulator (RTDS). In general, the harmonic profile of a fast controller has wide distribution due to the large bandwidth of the controller. The major contribution of this paper is that the proposed control strategy gives an improved voltage harmonic profile and distribute it more around the switching frequency along with fast transient response; filter design, thus, becomes easier. The implementation of a control strategy with high bandwidth in small time steps of Real Time Digital Simulator (RTDS) is not straight forward. This paper shows a good methodology for the practitioners to implement such control scheme in RTDS. As a part of the industrial process, the controller parameters are optimized using particle swarm optimization (PSO) technique to improve the low voltage ride through (LVRT) performance under network disturbance. The response surface methodology (RSM) is well adapted to build analytical models for recovery time (Rt), maximum percentage overshoot (MPOS), settling time (Ts), and steady state error (Ess) of the voltage profile immediate after inverter under disturbance. A systematic approach of controller parameter optimization is detailed. The transient performance of the PSO based optimization method applied to the proposed sliding mode controlled PV inverter is compared with the results from genetic algorithm (GA) based optimization technique. The reported real time implementation challenges and controller optimization procedure are applicable to other control applications in the field of renewable and distributed generation systems. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

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.

Isolated data acquisition system for high voltage applications

International Nuclear Information System (INIS)

Waitz, A.; Donaldson, A.

1985-06-01

This report describes the design and operation of a microcomputer controlled system for acquisition of both analog and binary data within the high voltage stages of a linac modulator. The system is comprised of a microprocessor Controller which communicates with the remote data Acquisition circuits via an optical bus. The bus, which uses a 1 MHz Manchester II format, is configured as a loop, starting at the Controller, daisy-chaining the remote cards and terminating back at the Controller. Upon receiving a linac timing pulse, the Controller sends addressed commands to the individual remote cards and receives data back. It then passes this data to the linac control system through a Multibus connection. Each remote circuit can return 16 binary sense and 7 (12 bit) analog parameters within 270 us. This speed is possible because of a pipelined design where one word is transmitted while another is being converted. A data conversion cycle is initiated when a remote data acquisition card receives the proper command and address from the controller

Multi-Period Optimization for Voltage Control System in Transmission Grids

DEFF Research Database (Denmark)

Qin, Nan; Chen, Si; Liu, Chengxi

2015-01-01

Automatic Voltage Control (AVC) systems maintain the voltage in an acceptable range and minimize the power loss of the grid by coordinately regulating the controllable components. Switchable shunts and tap-able transformers are expected to be operated as few times as possible. This paper proposes...

Performance analysis of pulse analog control schemes for LLC resonant DC/DC converters suitable in portable applications

Directory of Open Access Journals (Sweden)

P. Kowstubha

2016-12-01

Full Text Available Performance Analysis of Pulse Analog Control Schemes, predominantly Pulse-Width Modulation (PWM and Pulse-Position Modulation (PPM for LLC resonant DC/DC converter suitable in portable applications is addressed in this paper. The analysis is done for closed loop performance, frequency domain performance, primary and secondary side conduction losses and soft commutation using PSIM 6.0 software and observed that PPM scheme provides better performance at high input voltage with a good selectivity of frequency over a wide range of line and load variations. The performance of LLC resonant DC/DC converter is demonstrated using PPM scheme for a design specifications of 12 V, 5 A output.

System for high-voltage control detectors with large number photomultipliers

International Nuclear Information System (INIS)

Donskov, S.V.; Kachanov, V.A.; Mikhajlov, Yu.V.

1985-01-01

A simple and inexpensive on-line system for hihg-voltage control which is designed for detectors with a large number of photomultipliers is developed and manufactured. It has been developed for the GAMC type hodoscopic electromagnetic calorimeters, comprising up to 4 thousand photomultipliers. High voltage variation is performed by a high-speed potentiometer which is rotated by a microengine. Block-diagrams of computer control electronics are presented. The high-voltage control system has been used for five years in the IHEP and CERN accelerator experiments. The operation experience has shown that it is quite simple and convenient in operation. In case of about 6 thousand controlled channels in both experiments no potentiometer and microengines failures were observed

Calculation of comparators of analog-to-digital converters with account of electric regime of transistor operation and ionizing radiation effect; Raschet komparatov analogo-tsifrovykh preobrazovatelej s uchetom ehlektricheskogo rezhima raboty tranzistorov i vozdejstviya ioniziruyushchego izlucheniya

Energy Technology Data Exchange (ETDEWEB)

Ragozin, A Yu

1994-12-31

Zero shift voltage in comparators of analog-to-digital converters under gamma irradiation with regard to electric mode effect on bipolar transistor degradation is calculated. It is shown that the input range of comparators such weak units are represented by comparators of bipolar and lower grades.

Advanced dc motor controller for battery-powered electric vehicles

Science.gov (United States)

Belsterling, C. A.

1981-01-01

A motor generation set is connected to run from the dc source and generate a voltage in the traction motor armature circuit that normally opposes the source voltage. The functional feasibility of the concept is demonstrated with tests on a Proof of Principle System. An analog computer simulation is developed, validated with the results of the tests, applied to predict the performance of a full scale Functional Model dc Controller. The results indicate high efficiencies over wide operating ranges and exceptional recovery of regenerated energy. The new machine integrates both motor and generator on a single two bearing shaft. The control strategy produces a controlled bidirectional plus or minus 48 volts dc output from the generator permitting full control of a 96 volt dc traction motor from a 48 volt battery, was designed to control a 20 hp traction motor. The controller weighs 63.5 kg (140 lb.) and has a peak efficiency of 90% in random driving modes and 96% during the SAE J 227a/D driving cycle.

An area and power-efficient analog li-ion battery charger circuit.

Science.gov (United States)

Do Valle, Bruno; Wentz, Christian T; Sarpeshkar, Rahul

2011-04-01

The demand for greater battery life in low-power consumer electronics and implantable medical devices presents a need for improved energy efficiency in the management of small rechargeable cells. This paper describes an ultra-compact analog lithium-ion (Li-ion) battery charger with high energy efficiency. The charger presented here utilizes the tanh basis function of a subthreshold operational transconductance amplifier to smoothly transition between constant-current and constant-voltage charging regimes without the need for additional area- and power-consuming control circuitry. Current-domain circuitry for end-of-charge detection negates the need for precision-sense resistors in either the charging path or control loop. We show theoretically and experimentally that the low-frequency pole-zero nature of most battery impedances leads to inherent stability of the analog control loop. The circuit was fabricated in an AMI 0.5-μm complementary metal-oxide semiconductor process, and achieves 89.7% average power efficiency and an end voltage accuracy of 99.9% relative to the desired target 4.2 V, while consuming 0.16 mm(2) of chip area. To date and to the best of our knowledge, this design represents the most area-efficient and most energy-efficient battery charger circuit reported in the literature.

Systems and methods for providing power to a load based upon a control strategy

Science.gov (United States)

Perisic, Milun; Kajouke, Lateef A; Ransom, Ray M

2013-12-24

Systems and methods are provided for an electrical system. The electrical system includes a load, an interface configured to receive a voltage from a voltage source, and a controller configured to receive the voltage from the voltage source through the interface and to provide a voltage and current to the load. Wherein, when the controller is in a constant voltage mode, the controller provides a constant voltage to the load, when the controller is in a constant current mode, the controller provides a constant current to the load, and when the controller is in a constant power mode, the controller provides a constant power to the load.

Energy harvesting from an exercise bike using a switch-mode converter controlled generator

DEFF Research Database (Denmark)

Knott, Arnold; Lindberg-Poulsen, Kristian; Andersen, Thomas

2010-01-01

output of the bike. The complete controller design consists of this power stage, a control circuit, a startup circuit and an overvoltage protection circuit. A functional overview of the entire controller is presented in the paper, along with in-depth descriptions of the specific subcircuits designed....... The system is self-starting and does not require an external power source. There are two modes of operation: Voltage regulated 12V output for connection to a standard inverter, and unregulated output for charging of a 24V battery, with direct linear control of the rotor current, thus simulating road bike...... gearing. Prototype bikes were built and used at several events, and the functionality was experimentally verified....

Controlled Operation of the Islanded Portion of the International Council on Large Electric Systems (CIGRE Low Voltage Distribution Network

Directory of Open Access Journals (Sweden)

Ghullam Mustafa Bhutto

2017-07-01

Full Text Available In islanding, a portion of the power network, comprised of the loads and distributed generation (DG units, is isolated from the rest of the power grid and forms a micro grid (MG. In this condition, it becomes essential for the islanded MG to operate in a stable and controlled manner by providing ancillary services. When the MG is cut off from the main grid, the islanding must be detected by the DG units. In this condition it is essential that one of the controllers should be switched to the voltage-frequency (VF control mode. In islanding, the network loses it slack reference and this reference is established by a VF controller. The voltage and the frequency of the islanded MG deviate when disconnected from the transmission grid and these deviations are caused by the load-generation imbalance. The voltage and the frequency of the islanded MG can be restored to the permissible limits if the desired/exceeded amount of active and reactive power is injected/absorbed by the locally available sources in islanded MG. This paper proposes a control strategy which can compensate the voltage and the frequency deviations in the islanded portion of the International Council on Large Electric Systems (CIGRE low voltage distribution network by using advanced power electronics devices such as STATCOMs for Photovoltaic (PV Units and Battery Energy Storage Systems (BESS STATCOMs (for battery units. The selection of the VF controller for the most suitable DG unit of this test network is also presented in this paper, and the effectiveness of the controllers is verified by presenting simulation results using DIgSILENT (DIgSILENT GmbH, Gomaringen, Germany power factory software version 15.0.

Robust Fallback Scheme for the Danish Automatic Voltage Control System

DEFF Research Database (Denmark)

Qin, Nan; Dmitrova, Evgenia; Lund, Torsten

2015-01-01

This paper proposes a fallback scheme for the Danish automatic voltage control system. It will be activated in case of the local station loses telecommunication to the control center and/or the local station voltage violates the acceptable operational limits. It cuts in/out switchable and tap...... power system....

Circuit and method for controlling the threshold voltage of transistors.

NARCIS (Netherlands)

2008-01-01

A control unit, for controlling a threshold voltage of a circuit unit having transistor devices, includes a reference circuit and a measuring unit. The measuring unit is configured to measure a threshold voltage of at least one sensing transistor of the circuit unit, and to measure a threshold

Design and Implementation of a High-Voltage Generator with Output Voltage Control for Vehicle ER Shock-Absorber Applications

Directory of Open Access Journals (Sweden)

Chih-Lung Shen

2013-01-01

Full Text Available A self-oscillating high-voltage generator is proposed to supply voltage for a suspension system in order to control the damping force of an electrorheological (ER fluid shock absorber. By controlling the output voltage level of the generator, the damping force in the ER fluid shock absorber can be adjusted immediately. The shock absorber is part of the suspension system. The high-voltage generator drives a power transistor based on self-excited oscillation, which converts dc to ac. A high-frequency transformer with high turns ratio is used to increase the voltage. In addition, the system uses the car battery as dc power supply. By regulating the duty cycle of the main switch in the buck converter, the output voltage of the buck converter can be linearly adjusted so as to obtain a specific high voltage for ER. The driving system is self-excited; that is, no additional external driving circuit is required. Thus, it reduces cost and simplifies system structure. A prototype version of the actual product is studied to measure and evaluate the key waveforms. The feasibility of the proposed system is verified based on experimental results.

A New Secondary Control Approach for Voltage Regulation in DC Microgrids

DEFF Research Database (Denmark)

Peyghami, 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...

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.

Second-order Sliding Mode Control of DFIG Based Variable Speed Wind Turbine for Maximum Power Point Tracking

Institute of Scientific and Technical Information of China (English)

Xiangjie Liu; Chengcheng Wang; Yaozhen Han

2017-01-01

This paper proposes a super-twisting second order sliding mode control scheme to maximize the wind energy capture of a doubly fed induction generator based variable speed wind turbine (VSWT) system, and minimize the reactive power simultaneously. Two second order sliding mode controllers are designed to achieve the control objectives, reduce mechanical stress and improve control accuracy. By regulating the generator rotor voltage, one controller makes the wind turbine rotor speed track the optimal speed, which can maximize power generation. The other maintains the rotor current at rated value to minimize the reactive power. A quadratic form Lyapunov function is adopted to determine the range of controller parameters and guarantee the finite time stability. Simulation results on a 1.5 MW doubly fed induction generator (DFIG)-based variable speed wind turbine demonstrate the validity of the proposed control strategy.

Control and Protection Cooperation Strategy for Voltage Instability

DEFF Research Database (Denmark)

Liu, Zhou; Chen, Zhe; Sun, Haishun

2012-01-01

Most cascaded blackouts are caused by unexpected backup relay operations due to low voltage or overload state caused by post fault load restoration dynamics. If such state can be sensed and adjusted appropriately prior to those relay actions, system stability might be sustained. This paper proposed...... a control and protection cooperation strategy to prevent post fault voltage instability. The multi-agent technology is applied for the strategy implementation; the criteria based on wide area measured apparent impedances are defined to choose the control strategy, such as tap changer adjusting or load...

Strategies for Voltage Control and Transient Stability Assessment

Energy Technology Data Exchange (ETDEWEB)

Hiskens, Ian A.

2013-09-25

As wind generation grows, its influence on power system performance will becoming increasingly noticeable. Wind generation di ffers from traditional forms of generation in numerous ways though, motivating the need to reconsider the usual approaches to power system assessment and performance enhancement. The project has investigated the impact of wind generation on transient stability and voltage control, identifying and addressing issues at three distinct levels of the power system: 1) at the device level, the physical characteristics of wind turbine generators (WTGs) are quite unlike those of synchronous machines, 2) at the wind-farm level, the provision of reactive support is achieved through coordination of numerous dissimilar devices, rather than straightforward generator control, and 3) from a systems perspective, the location of wind-farms on the sub-transmission network, coupled with the variability inherent in their power output, can cause complex voltage control issues. The project has sought to develop a thorough understanding of the dynamic behaviour of type-3 WTGs, and in particular the WECC generic model. The behaviour of such models is governed by interactions between the continuous dynamics of state variables and discrete events associated with limits. It was shown that these interactions can be quite complex, and may lead to switching deadlock that prevents continuation of the trajectory. Switching hysteresis was proposed for eliminating deadlock situations. Various type-3 WTG models include control blocks that duplicate integrators. It was shown that this leads to non-uniqueness in the conditions governing steady-state, and may result in pre- and post-disturbance equilibria not coinciding. It also gives rise to a zero eigenvalue in the linearized WTG model. In order to eliminate the anomalous behaviour revealed through this investigation, WECC has now released a new generic model for type-3 WTGs. Wind-farms typically incorporate a variety of

A 16-Channel CMOS Chopper-Stabilized Analog Front-End ECoG Acquisition Circuit for a Closed-Loop Epileptic Seizure Control System.

Science.gov (United States)

Wu, Chung-Yu; Cheng, Cheng-Hsiang; Chen, Zhi-Xin

2018-06-01

In this paper, a 16-channel analog front-end (AFE) electrocorticography signal acquisition circuit for a closed-loop seizure control system is presented. It is composed of 16 input protection circuits, 16 auto-reset chopper-stabilized capacitive-coupled instrumentation amplifiers (AR-CSCCIA) with bandpass filters, 16 programmable transconductance gain amplifiers, a multiplexer, a transimpedance amplifier, and a 128-kS/s 10-bit delta-modulated successive-approximation-register analog-to-digital converter (SAR ADC). In closed-loop seizure control system applications, the stimulator shares the same electrode with the AFE amplifier for effective suppression of epileptic seizures. To prevent from overstress in MOS devices caused by high stimulation voltage, an input protection circuit with a high-voltage-tolerant switch is proposed for the AFE amplifier. Moreover, low input-referred noise is achieved by using the chopper modulation technique in the AR-CSCCIA. To reduce the undesired effects of chopper modulation, an improved offset reduction loop is proposed to reduce the output offset generated by input chopper mismatches. The digital ripple reduction loop is also used to reduce the chopper ripple. The fabricated AFE amplifier has 49.1-/59.4-/67.9-dB programmable gain and 2.02-μVrms input referred noise in a bandwidth of 0.59-117 Hz. The measured power consumption of the AFE amplifier is 3.26 μW per channel, and the noise efficiency factor is 3.36. The in vivo animal test has been successfully performed to verify the functions. It is shown that the proposed AFE acquisition circuit is suitable for implantable closed-loop seizure control systems.

An automatic method to analyze the Capacity-Voltage and Current-Voltage curves of a sensor

CERN Document Server

AUTHOR|(CDS)2261553

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.

Buck supplies output voltage ripple reduction using fuzzy control

Directory of Open Access Journals (Sweden)

Nicu BIZON

2007-12-01

Full Text Available Using the PWM control for switching power supplies the peaks EMI noise appear at the switching frequency and its harmonics. Using randomize or chaotic PWM control techniques in these systems the power spectrum is spread out in all frequencies band spectral emissions, but with a bigger ripple in the output voltage. The proposed nonlinear feedback control method, which induces chaos, is based by fuzzy rules that minimize the output voltage ripple. The feasibility and effectiveness of this relative simple method is shown by simulation. A comparison with the previous control method is included, too.

Voltage-Controlled Reconfigurable Spin-Wave Nanochannels and Logic Devices

Science.gov (United States)

Rana, Bivas; Otani, YoshiChika

2018-01-01

Propagating spin waves (SWs) promise to be a potential information carrier in future spintronics devices with lower power consumption. Here, we propose reconfigurable nanochannels (NCs) generated by voltage-controlled magnetic anisotropy (VCMA) in an ultrathin ferromagnetic waveguide for SW propagation. Numerical micromagnetic simulations are performed to demonstrate the confinement of magnetostatic forward volumelike spin waves in NCs by VCMA. We demonstrate that the NCs, with a width down to a few tens of a nanometer, can be configured either into a straight or curved structure on an extended SW waveguide. The key advantage is that either a single NC or any combination of a number of NCs can be easily configured by VCMA for simultaneous propagation of SWs either with the same or different wave vectors according to our needs. Furthermore, we demonstrate the logic operation of a voltage-controlled magnonic xnor and universal nand gate and propose a voltage-controlled reconfigurable SW switch for the development of a multiplexer and demultiplexer. We find that the NCs and logic devices can even be functioning in the absence of the external-bias magnetic field. These results are a step towards the development of all-voltage-controlled magnonic devices with an ultralow power consumption.

Direct harmonic voltage control strategy for shunt active power filter

DEFF Research Database (Denmark)

Munir, Hafiz Mudassir; Zou, JianXiao; Xie, Chuan

2017-01-01

generation system (DPGS) where the nonlinear loads are highly dispersed. Local harmonic voltage detection based Resistive-APF (R-APF) seems more suitable to be applied in the DPGS, however, R-APF suffers from poor compensation performance and difficulty of parameter tuning. In this paper, a direct harmonic...... voltage control strategy for the S-APF is proposed with local point of common coupling (PCC) voltage detection only. The control strategy design procedure is given in detail. Simulation is conducted in Matlab/Simulink to compare the performance between the R-APF and the proposed method. The results...

Coupling analysis of energy conversion in multi-mode vibration structural control using a synchronized switch damping method

International Nuclear Information System (INIS)

Ji, Hongli; Qiu, Jinhao; Xia, Pinqi; Inman, Daniel

2012-01-01

Modal coupling is an important issue in the analysis and control of structural systems with multi-degrees of freedom (MDOF). In this paper, modal coupling induced by energy conversion in the structural control of an MDOF system using a synchronized switch damping method is investigated theoretically and validated numerically. In the analysis, it is supposed that the voltage on the piezoelectric actuator is switched at the displacement extrema of a given mode. Two types of coupling in energy conversion are considered. The first is whether the switching action based on one mode induces energy conversion of the other modes. The second is whether the vibration of one mode affects the energy conversion of the other modes. The results indicate that the modal coupling in energy conversion is very complicated. In most cases the switching action based on one mode does induce energy conversion of another mode, but the efficiency depends on the frequency ratio of the two modes. The vibration of one mode affects the energy conversion of another mode only when the frequency ratio of the two modes takes some special values. Discussions are also given on the potential application of the theoretical results in the design of an energy harvesting device. (paper)

A Zero Input Current Ripple ZVS/ZCS Boost Converter with Boundary-Mode Control

Directory of Open Access Journals (Sweden)

Ching-Ming Lai

2014-10-01

Full Text Available In this paper, in order to achieve zero ripple conditions, the use of a ripple mirror (RM circuit for the boost converter is proposed. The operation modes are studied and steady-state analyses performed to show the merits of the proposed converter. It is found that the proposed RM circuit technique can provide much better flexibility than the two-phase interleaved boost converter for locating the zero ripple operating point in the design stage. In addition, the choice of using a boundary-mode control is mainly based on the consideration of achieving both ZVS (zero voltage switching/ZCS (zero current switching soft-switching and constant on-time control for the converter. To verify the performance of the proposed converter, a 48 V input and 200 W/200 V output prototype is constructed. Experimental results verify the effectiveness of the proposed converter.

Experiences in simulating and testing coordinated voltage control provided by multiple wind power plants

Energy Technology Data Exchange (ETDEWEB)

Arlaban, T.; Alonso, O.; Ortiz, D. [Acciona Windpower S.A. (Spain); Peiro, J.; Rivas, R. [Red Electrica de Espana SAU (Spain); Quinonez-Varela, G.; Lorenzo, P. [Acciona Energia S.A. (Spain)

2011-07-01

This document presents some field tests performed in a transmission system node in order to check the adequacy of voltage control performance by multiple wind power plants, with an overall capacity of 395 MW. It briefly explains the Spanish TSO motivation towards new voltage control requirements and the necessity of performing such tests in order to set the most convenient voltage control parameters and to verify the stable operation. It presents how different the voltage control capability between modern wind turbines (DFIG) and older ones (SCIG) specifically retrofitted for voltage control is. (orig.)

Voltage stability analysis considering the load dynamic characteristics and the voltage control devices; Analisis de estabilidad de voltaje considerando las caracteristicas dinamicas de la carga y dispositivos de control de voltaje

Energy Technology Data Exchange (ETDEWEB)

Hernandez Alvarez, Enrique

2001-09-15

The research work presented in this thesis, is centered in the voltage stability analysis of medium term considering the effect of the load characteristics and its interaction with the voltage control device models in the transmission network. More concretely, a type of load model is defined and studied with desirable characteristics for the study of the voltage stability, the generic load models derived from field tests and from the application of identification techniques and it is analyzed the influence of the application of control systems to improve the system stability margins. Also, alternatives to the power system modeling for the voltage stability study in complex systems are reviewed. In the first place a fundamental analysis of the voltage characteristics and stability in a simplified power system is presented and the method of adopted analysis is introduced. It is shown that the instability phenomenon is manifested as a singular type bifurcation induced from the critical way of voltage when the system is operated under stress conditions. Next, the contribution of the action of the control devices to the stability margin is analyzed and criteria of the stability analyses are deducted based on the study of such mode. Following a linear model of the power system with desirable characteristics for the study of the voltage stability of medium term is proposed and the characteristics of stability in the context of the study of complex systems are interpreted. The proposed analysis tool is based on the physical notion that the behavior of the voltage control systems in the generators is very rapid with regard to the behavior of the load and has its main application in the preliminary study of the voltage stability of medium and long term. From this model, an analytical tool based on the application of techniques of linear analysis is proposed to approach the problem of determination of critical voltage areas and the contribution of control devices to the

Annealing, temperature, and bias-induced threshold voltage instabilities in integrated E/D-mode InAlN/GaN MOS HEMTs

Science.gov (United States)

Blaho, M.; Gregušová, D.; Haščík, Š.; Ťapajna, M.; Fröhlich, K.; Šatka, A.; Kuzmík, J.

2017-07-01

Threshold voltage instabilities are examined in self-aligned E/D-mode n++ GaN/InAlN/GaN MOS HEMTs with a gate length of 2 μm and a source-drain spacing of 10 μm integrated in a logic invertor. The E-mode MOS HEMT technology is based on selective dry etching of the cap layer which is combined with Al2O3 grown by atomic-layer deposition at 380 K. In the D-mode MOS HEMT, the gate recessing is skipped. The nominal threshold voltage (VT) of E/D-mode MOS HEMTs was 0.6 and -3.4 V, respectively; the technology invariant maximal drain current was about 0.45 A/mm. Analysis after 580 K/15 min annealing step and at an elevated temperature up to 430 K reveals opposite device behavior depending on the HEMT operational mode. It was found that the annealing step decreases VT of the D-mode HEMT due to a reduced electron injection into the modified oxide. On the other hand, VT of the E-mode HEMT increases with reduced density of surface donors at the oxide/InAlN interface. Operation at the elevated temperature produces reversible changes: increase/decrease in the VT of the respective D-/E-mode HEMTs. Additional bias-induced experiments exhibit complex trapping phenomena in the devices: Coaction of shallow (˜0.1 eV below EC) traps in the GaN buffer and deep levels at the oxide/InAlN interface was identified for the E-mode device, while trapping in the D-mode HEMTs was found to be consistent with a thermo-ionic injection of electrons into bulk oxide traps (˜0.14 eV above EF) and trapping at the oxide/GaN cap interface states.

Voltage Control Support and Coordination between Renewable Generation Plants in MV Distribution Systems

DEFF Research Database (Denmark)

Petersen, Lennart; Iov, Florin; Hansen, Anca Daniela

2016-01-01

This paper focusses on voltage control support and coordination between renewable generation plants in medium voltage distribution systems. An exemplary benchmark grid in Denmark, including a number of flexible ReGen plants providing voltage control functionality, is used as a base case. First......, voltage sensitivity analysis is performed to quantify node voltage variations due to injections of reactive power for given operational points of the network. The results are then used to develop an adaptive voltage droop control method, where various droop settings are allocated to each ReGen plant...... according to the sensitivity indices of corresponding node voltages and the location of respective ReGen plants in the distribution system. Case studies are performed in time-domain to analyze the impact of voltage fluctuations due to active power variations of ReGen plants in order to verify...

A large dynamic range radiation tolerant analog memory in a quarter micron CMOS technology

CERN Document Server

Anelli, G; Rivetti, A

2000-01-01

A 8*128 cell analog memory prototype has been designed in a commercial 0.25 jam CMOS process. The aim of this work was to investigate the possibility of designing large dynamic range mixed- mode switched capacitor circuits for High-Energy Physics (HEP) applications in deep submicron CMOS technologies. Special layout techniques have been used to make the circuit radiation tolerant left bracket 1 right bracket . The memory cells employ gate-oxide capacitors for storage, allowing for a very high density. A voltage write - voltage read architecture has been chosen to minimize the sensitivity to absolute capacitor values. The measured input voltage range is 2.3 V (V//D//D = 2.5 V), with a linearity of at least 7.5 bits over 2 V. The dynamic range is more than 11 bits. The pedestal variation is plus or minus 0.5 mV peak-to-peak. The noise measured, which is dominated by the noise of the measurement setup, is around 0.8 mV rms. The characteristics of the memory have been measured before irradiation and after lOMrd (...

A Uniform Voltage Gain Control for Alignment Robustness in Wireless EV Charging

Directory of Open Access Journals (Sweden)

Yabiao Gao

2015-08-01

Full Text Available The efficiency of wireless power transfer is sensitive to the horizontal and vertical distances between the transmitter and receiver coils due to the magnetic coupling change. To address the output voltage variation and efficiency drop caused by misalignment, a uniform voltage gain frequency control is implemented to improve the power delivery and efficiency of wireless power transfer under misalignment. The frequency is tuned according to the amplitude and phase-frequency characteristics of coupling variations in order to maintain a uniform output voltage in the receiver coil. Experimental comparison of three control methods, including fixed frequency control, resonant frequency control, and the proposed uniform gain control was conducted and demonstrated that the uniform voltage gain control is the most robust method for managing misalignment in wireless charging applications.

Voltage-controlled colour-tunable microcavity OLEDs with enhanced colour purity

International Nuclear Information System (INIS)

Choy, Wallace C H; Niu, J H; Li, W L; Chui, P C

2008-01-01

The emission spectrum of single-unit voltage-controlled colour-tunable organic light emitting devices (OLEDs) has been theoretically and experimentally studied. Our results show that by introducing the microcavity structure, the colour purity of not only the destination colour but also the colour-tunable route can be enhanced, while colour purity is still an issue in typical single-unit voltage-controlled colour-tunable OLEDs. With the consideration of the periodical cycling of resonant wavelength and absorption loss of the metal electrodes, the appropriate change in the thickness of the microcavity structure has been utilized to achieve voltage-controlled red-to-green and red-to-blue colour-tunable OLEDs without adding dyes or other organic materials to the OLEDs

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

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 of the distu......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...

Feedback control of resistive wall modes in toroidal devices

International Nuclear Information System (INIS)

Liu, Y.Q.

2002-01-01

Active feedback of resistive wall modes is investigated using cylindrical theory and toroidal calculations. For tokamaks, good performance is obtained by using active coils with one set of coils in the poloidal direction and sensors detecting the poloidal field inside the first wall, located at the outboard mid-plane. With suitable width of the feedback coil such a system can give robust control with respect to variations in plasma current, pressure and rotation. Calculations are shown for ITER-like geometry with a double wall. The voltages and currents in the active coils are well within the design limits for ITER. Calculations for RFP's are presented for a finite number of coils both in the poloidal and toroidal directions. With 4 coils in the poloidal and 24 coils in the toroidal direction, all non-resonant modes can be stabilized both at high and low theta. Several types of sensors, including radial and internal poloidal or toroidal sensors, can stabilize the RWM, but poloidal sensors give the most robust performance. (author)

Artificial intelligence techniques for voltage control

Energy Technology Data Exchange (ETDEWEB)

Ekwue, A.; Cheng, D.T.Y.; Macqueen, J.F.

1997-12-31

In electric power systems, the advantages of reactive power dispatching or optimisation include improved utilisation of reactive power sources and hence reduction in reactive power flows and real losses of the system; unloading of the system and equipment as a result of reactive flow reduction; the power factors of generation are improved and system security is enhanced; reduced voltage gradients and somewhat higher voltages which result across the system from improved operation; deferred capital investment is new reactive power sources as a result of improved utilisation of existing equipment; and for the National Grid Company plc (NGC), the main advantage is reduced out-of-merit operation. The problem of reactive power control has been studied and widely reported in the literature. Non-linear programming methods as well as linear programming techniques for constraint dispatch have been described. Static optimisation of reactive power sources by the use of sensitivity analysis was described by Kishore and Hill. Long range optimum var planning has been considered and the optimum amount and location of network reactive compensation so as to maintain the system voltage within the desired limits, while operating under normal and various insecurity states, have also been studied using several methods. The objective of this chapter is therefore to review conventional methods as well as AI techniques for reactive power control. (Author)

Secondary Frequency and Voltage Control of Islanded Microgrids via Distributed Averaging

DEFF Research Database (Denmark)

W. Simpson-Porco, John; Shafiee, Qobad; Dorfler, Florian

2015-01-01

actions. The frequency controller rapidly regulates the microgrid frequency to its nominal value while maintaining active power sharing among the distributed generators. Tuning of the voltage controller provides a simple and intuitive trade-off between the conflicting goals of voltage regulation...

Coordinated voltage control in offshore HVDC connected cluster of wind power plants

DEFF Research Database (Denmark)

Sakamuri, Jayachandra Naidu; Rather, Zakir Hussain; Rimez, Johan

This paper presents a coordinated voltage control scheme (CVCS) for a cluster of offshore wind power plants connected to a voltage-source converter-based high-voltage direct current system. The primary control point of the proposed voltage control scheme is the introduced Pilot bus, which is having...... by dispatching reactive power references to each wind turbine (WT) in the wind power plant cluster based on their available reactive power margin and network sensitivity-based participation factors, which are derived from the dV/dQ sensitivity of a WT bus w.r.t. the Pilot bus. This method leads...

Fuel Cell/Electrochemical Cell Voltage Monitor

Science.gov (United States)

Vasquez, Arturo

2012-01-01

A concept has been developed for a new fuel cell individual-cell-voltage monitor that can be directly connected to a multi-cell fuel cell stack for direct substack power provisioning. It can also provide voltage isolation for applications in high-voltage fuel cell stacks. The technology consists of basic modules, each with an 8- to 16-cell input electrical measurement connection port. For each basic module, a power input connection would be provided for direct connection to a sub-stack of fuel cells in series within the larger stack. This power connection would allow for module power to be available in the range of 9-15 volts DC. The relatively low voltage differences that the module would encounter from the input electrical measurement connection port, coupled with the fact that the module's operating power is supplied by the same substack voltage input (and so will be at similar voltage), provides for elimination of high-commonmode voltage issues within each module. Within each module, there would be options for analog-to-digital conversion and data transfer schemes. Each module would also include a data-output/communication port. Each of these ports would be required to be either non-electrical (e.g., optically isolated) or electrically isolated. This is necessary to account for the fact that the plurality of modules attached to the stack will normally be at a range of voltages approaching the full range of the fuel cell stack operating voltages. A communications/ data bus could interface with the several basic modules. Options have been identified for command inputs from the spacecraft vehicle controller, and for output-status/data feeds to the vehicle.

Transistor analogs of emergent iono-neuronal dynamics.

Science.gov (United States)

Rachmuth, Guy; Poon, Chi-Sang

2008-06-01

Neuromorphic analog metal-oxide-silicon (MOS) transistor circuits promise compact, low-power, and high-speed emulations of iono-neuronal dynamics orders-of-magnitude faster than digital simulation. However, their inherently limited input voltage dynamic range vs power consumption and silicon die area tradeoffs makes them highly sensitive to transistor mismatch due to fabrication inaccuracy, device noise, and other nonidealities. This limitation precludes robust analog very-large-scale-integration (aVLSI) circuits implementation of emergent iono-neuronal dynamics computations beyond simple spiking with limited ion channel dynamics. Here we present versatile neuromorphic analog building-block circuits that afford near-maximum voltage dynamic range operating within the low-power MOS transistor weak-inversion regime which is ideal for aVLSI implementation or implantable biomimetic device applications. The fabricated microchip allowed robust realization of dynamic iono-neuronal computations such as coincidence detection of presynaptic spikes or pre- and postsynaptic activities. As a critical performance benchmark, the high-speed and highly interactive iono-neuronal simulation capability on-chip enabled our prompt discovery of a minimal model of chaotic pacemaker bursting, an emergent iono-neuronal behavior of fundamental biological significance which has hitherto defied experimental testing or computational exploration via conventional digital or analog simulations. These compact and power-efficient transistor analogs of emergent iono-neuronal dynamics open new avenues for next-generation neuromorphic, neuroprosthetic, and brain-machine interface applications.

Reactive power and voltage control strategy based on dynamic and adaptive segment for DG inverter

Science.gov (United States)

Zhai, Jianwei; Lin, Xiaoming; Zhang, Yongjun

2018-03-01

The inverter of distributed generation (DG) can support reactive power to help solve the problem of out-of-limit voltage in active distribution network (ADN). Therefore, a reactive voltage control strategy based on dynamic and adaptive segment for DG inverter is put forward to actively control voltage in this paper. The proposed strategy adjusts the segmented voltage threshold of Q(U) droop curve dynamically and adaptively according to the voltage of grid-connected point and the power direction of adjacent downstream line. And then the reactive power reference of DG inverter can be got through modified Q(U) control strategy. The reactive power of inverter is controlled to trace the reference value. The proposed control strategy can not only control the local voltage of grid-connected point but also help to maintain voltage within qualified range considering the terminal voltage of distribution feeder and the reactive support for adjacent downstream DG. The scheme using the proposed strategy is compared with the scheme without the reactive support of DG inverter and the scheme using the Q(U) control strategy with constant segmented voltage threshold. The simulation results suggest that the proposed method has a significant improvement on solving the problem of out-of-limit voltage, restraining voltage variation and improving voltage quality.

Improved model predictive control for high voltage quality in microgrid applications

DEFF Research Database (Denmark)

Dragicevic, T.; Al hasheem, Mohamed; Lu, M.

2017-01-01

This paper proposes an improvement of the finite control set model predictive control (FCS-MPC) strategy for enhancing the voltage regulation performance of a voltage source converter (VSC) used for standalone microgrid and uninterrupted power supply (UPS) applications. The modification is based...

Modeling generalized interline power-flow controller (GIPFC using 48-pulse voltage source converters

Directory of Open Access Journals (Sweden)

Amir Ghorbani

2018-05-01

Full Text Available Generalized interline power-flow controller (GIPFC is one of the voltage-source controller (VSC-based flexible AC transmission system (FACTS controllers that can independently regulate the power-flow over each transmission line of a multiline system. This paper presents the modeling and performance analysis of GIPFC based on 48-pulsed voltage-source converters. This paper deals with a cascaded multilevel converter model, which is a 48-pulse (three levels voltage source converter. The voltage source converter described in this paper is a harmonic neutralized, 48-pulse GTO converter. The GIPFC controller is based on d-q orthogonal coordinates. The algorithm is verified using simulations in MATLAB/Simulink environment. Comparisons between unified power flow controller (UPFC and GIPFC are also included. Keywords: Generalized interline power-flow controller (GIPFC, Voltage source converter (VCS, 48-pulse GTO converter

Voltage control and protection in electrical power systems from system components to wide-area control

CERN Document Server

Corsi, Sandro

2015-01-01

Based on the author’s twenty years of experience, this book shows the practicality of modern, conceptually new, wide area voltage control in transmission and distribution smart grids, in detail. Evidence is given of the great advantages of this approach, as well as what can be gained by new control functionalities which modern technologies now available can provide. The distinction between solutions of wide area voltage regulation (V-WAR) and wide area voltage protection (V-WAP) are presented, demonstrating the proper synergy between them when they operate on the same power system as well as the simplicity and effectiveness of the protection solution in this case. The author provides an overview and detailed descriptions of voltage controls, distinguishing between generalities of underdeveloped, on-field operating applications and modern and available automatic control solutions, which are as yet not sufficiently known or perceived for what they are: practical, high-performance and reliable solutions. At th...

Hardware Evolution of Analog Speed Controllers for a DC Motor

Science.gov (United States)

Gwaltney, David A.; Ferguson, Michael I.

2003-01-01

This viewgraph presentation provides information on the design of analog speed controllers for DC motors on aerospace systems. The presentation includes an overview of controller evolution, evolvable controller configuration, an emphasis on proportion integral (PI) controllers, schematic diagrams, and experimental results.

Active Power Filter DC Bus Voltage Piecewise Reaching Law Variable Structure Control

Directory of Open Access Journals (Sweden)

Baolian Liu

2014-01-01

Full Text Available The DC bus voltage stability control is one key technology to ensure that Active Power Filter (APF operates stably. The external disturbances such as power grid and load fluctuation and the system parameters changing may affect the stability of APF DC bus voltage and the normal operation of APF. The mathematical model of DC bus voltage is established according to power balance principle and a DC bus voltage piecewise reaching law variable structure control algorithm is proposed to solve the above problem, and the design method is given. The simulation and experiment results proved that the proposed variable structure control algorithm can eliminate the chattering problem existing in traditional variable structure control effectively, is insensitive to system disturbance, and has good robustness and fast dynamic response speed and stable DC bus voltage with small fluctuation. The above advantages ensure the compensation effect of APF.

Variable speed wind turbine generator system with current controlled voltage source inverter

International Nuclear Information System (INIS)

Muyeen, S.M.; Al-Durra, Ahmed; Tamura, J.

2011-01-01

highlights: → Current controlled voltage source inverter scheme for wind power application. → Low voltage ride through of wind farm. → Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

Variable speed wind turbine generator system with current controlled voltage source inverter

Energy Technology Data Exchange (ETDEWEB)

Muyeen, S.M., E-mail: muyeen0809@yahoo.co [Dept. of Electrical Engineering, Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Al-Durra, Ahmed [Dept. of Electrical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Tamura, J. [Dept. of EEE, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507 (Japan)