Topological Design and Modulation Strategy for Buck-Boost Three-Level Inverters
DEFF Research Database (Denmark)
Teodorescu, Remus; Gao, F.; Blaabjerg, Frede;
2007-01-01
buck-boost three-level inverters that can also support bidirectional power conversion. The proposed front-end circuitry is developed from the Â¿uk-derived buck-boost two-level inverter, and by using the "alternative phase opposition disposition" (APOD) modulation scheme, the buck-boost three......-level inverters can perform distinct five-level line voltage and three-level phase voltage switching by simply controlling the active switches located in the designed voltage boost section of the circuits. As a cost saving option, one active switch can further be removed from the voltage-boost section...
Enhanced Buck-Boost Three-Level Neutral-Point-Clamped Inverters
DEFF Research Database (Denmark)
Tan, K. K.; Gao, F.; Chiang Loh, Poh;
2009-01-01
In traditional three-level neutral-point-clamped (NPC) inverters, a major issue is capacitor voltage imbalance, which results in low order harmonics. The compensation of the capacitor voltages often require additional control complexity, which cannot be conveniently implemented. The "alternative...... method, with the ability to easily adjust for capacitor voltage imbalances. To further improve the boost capability of the three-level NPC inverters, another new topology introduces 2 additional diodes,achieving higher boost performance while totally eliminating thepossibility of capacitor voltage...... phase opposition disposition" (APOD) modulation method used in traditional NPC topologies also has lower harmonics performance as compared to the "phase disposition" (PD) modulation method.In this paper, we introduce a new three-level NPC topology that utilises the harmonically superior PD modulation...
Topological Design and Modulation Strategy for Buck-Boost Three-Level Inverters
DEFF Research Database (Denmark)
Gao, Feng; Loh, Poh Chiang; Teodorescu, Remus;
2009-01-01
can perform distinct five-level line voltage and three-level phase voltage switching by simply controlling the active switches located in the designed voltage boost section of the circuits. As a cost saving option, one active switch can further be removed from the voltage boost section of the circuits...
Diode-assisted buck-boost voltage source inverters
DEFF Research Database (Denmark)
Gao, F.; Loh, P.C.; Teodorescu, Remus;
2007-01-01
This paper proposes buck-boost voltage source inverters with a unique X-shape diode-capacitor network inserted between inverter circuitry and dc source for producing a large voltage boost gain. Comparing with other voltage buck-boost techniques, the presented topologies with only a little more...... passive components can significantly enhance voltage boost capability for dc-ac inversion. With different front-end circuitries, the diode-assisted buck-boost inverters can show different operational principle and voltage boost ratio. Carefully analyzing the operational principle for the inherent energy...
Diode-Assisted Buck-Boost Voltage-Source Inverters
DEFF Research Database (Denmark)
Gao, Feng; Loh, Poh Chiang; Teodorescu, Remus;
2009-01-01
This paper proposes a number of diode-assisted buck-boost voltage-source inverters with a unique X-shaped diode-capacitor network inserted between the inverter circuitry and dc source for producing a voltage gain that is comparatively higher than those of other buck-boost conversion techniques....... Using the diode-assisted network, the proposed inverters can naturally configure themselves to perform capacitive charging in parallel and discharging in series to give a higher voltage multiplication factor without compromising waveform quality. In addition, by adopting different front-end circuitries...
Component-Minimized Buck-Boost Voltage Source Inverters
DEFF Research Database (Denmark)
Gao, F.; Loh, P.C.; Blaabjerg, Frede;
2007-01-01
order to form a distinct neutral potential in the corresponding voltage boost circuitry for correct B4 inverter operation, necessary modifications are derived step by step. The resulted dc networks with symmetrical placement of passive components allow complete charging and equal energy distribution...... between capacitors. Modulation wise, the proposed buck-boost B4 inverters can be controlled using a carefully designed carrier-based pulse-width modulation (PWM) scheme that will always ensure balanced threephase outputs as desired, while simultaneously achieving minimal voltage stress across...
Buck-Boost Current-Source Inverters With Diode-Inductor Network
DEFF Research Database (Denmark)
Gao, Feng; Liang, Chao; Loh, Poh Chiang;
2009-01-01
compared with other recently reported buck-boost CSIs. For controlling the proposed CSIs, two modulation schemes are designed for achieving either optimized harmonic performance or minimized commutation count without influencing the inverter current buck-boost gain. These theoretical findings were...
Novel Family of modified qZS buck-boost multilevel inverters with reduced switch count
DEFF Research Database (Denmark)
Husev, Oleksandr; Strzelecki, Ryszard; Blaabjerg, Frede;
2015-01-01
This paper describes a novel family of modified quasi-Z-source buck-boost multilevel inverters with reduced switch count. The inverters are derived by means of the modified inverter configuration with quasi-Z-source networks. The main benefits of the proposed solutions lie in the increased amount...
Pulse width modulated buck-boost five-level current source inverters
DEFF Research Database (Denmark)
Blaabjerg, Frede; Gao, F.; Loh, P.C.;
2008-01-01
This paper presents new five-level current source inverters (CSIs) with voltage/current buck-boost capability. Being different from the existing multilevel CSI, the proposed CSIs were first designed to regulate the flowing path of dc input current by controlling two additional active switches......, resulting in the natural balance of input current. For maintaining the normalized volt-sec average unchanged, the alternative phase opposition disposition (APOD) modulation scheme with typical gating signal mapping technique from voltage source inverter (VSI) to CSI can be assumed to control the five-level...... buck-boost CSIs. Next by observing the hidden current charging path during inductive charging interval under APOD modulation, it is noted that the buck-boost five-level CSI can then be further modified with lesser active component without degrading output performance. To verify the theoretical findings...
Non-Inverting Buck-Boost Converter for Fuel Cell Applications
DEFF Research Database (Denmark)
Schaltz, Erik; Rasmussen, Peter Omand; Khaligh, Alireza
2008-01-01
Fuel cell DC/DC converters often have to be able to both step-up and step-down the input voltage, and provide a high efficiency in the whole range of output power. Conventional negative output buck-boost and non-inverting buck-boost converters provide both step-up and step-down characteristics....... In this paper the non-inverting buck-boost with either diodes or synchronous rectifiers is investigated for fuel cell applications. Most of previous research does not consider the parasitic in the evaluation of the converters. In this study, detailed analytical expressions of the efficiencies for the system...... composed of fuel cell system and interfacing converter, considering the parasitics, are presented. It is concluded that the implementation with synchronous rectifiers provides the highest efficiency in the whole range of the fuel cell power, and its efficiency characteristic is more suitable for fuel cell...
Single stage buck-boost DC-AC neutral point clamped inverter
DEFF Research Database (Denmark)
Mo, Wei; Loh, Poh Chiang; Andrew, A.;
2012-01-01
This paper proposes a new single stage buck-boost DC-AC neutral point clamped inverter topology which integrates the cascaded configurations of recently introduced inductor-capacitor-capacitor-transformer impedance source network (by Adamowicz) and classic NPC configuration. As a consequence...... windings thus preventing the core from saturation; lowers the voltage stresses and power losses of inverter switches and reduces the sizes of filtering devices and as well as obtains better output performance compared to the original two-level Z-source inverters. A phase disposition pulse width modulation...
Three-Level Z-Source Inverters Using a Single LC Impedance Network
DEFF Research Database (Denmark)
Loh, Poh Chiang; Lim, Sok Wei; Gao, Feng;
2007-01-01
Three-level Z-source inverters are recent single-stage topological solutions proposed for buck-boost energy conversion with all favorable advantages of three-level switching retained. Despite their effectiveness in achieving voltage buck-boost conversion, existing three-level Z-source inverters use...... three-level Z-source inverters, whose output voltage can be stepped down or up using only a single LC impedance network connected between the dc input source and either a neutral-point-clamped (NPC) or dc-link cascaded inverter circuitry. Through careful design of their modulation scheme, both inverters...... can function with the minimum of six device commutations per half carrier cycle (similar to that needed by a traditional buck three-level NPC inverter), while producing the correct volt-sec average and inductive voltage boosting at their ac output terminals. Physically, the designed modulation scheme...
DEFF Research Database (Denmark)
Chiang Loh, Poh; Gao, Feng; Blaabjerg, Frede;
2009-01-01
Three-level Z-source inverters are recent single-stage topological solutions proposed for buck-boost energy conversion with all favorable advantages of three-level switching retained. Despite their proven buck-boost capability, existing three-level Zsource inverters are either too costly with...... numerous passive LC elements needed or poor in spectral quality if the "reduced element count" (REC) variant is used. Instead of being constrained by the tradeoff, this paper proposes an alternative three-level Z-source topological and control combination that can produce optimal output waveform quality...... while using lesser passive LC elements. Through detailed operational analysis, new operating modes of the REC Z-source inverters are identified, which when inserted appropriately to the inverter state sequence will always produce the desired voltage transfer gain with minimized commutation count and...
DEFF Research Database (Denmark)
Loh, Poh Chiang; Blaabjerg, Frede; Lim, Sok Wei;
2007-01-01
Three-level Z-source inverters are recent single-stage topological solutions proposed for buck-boost energy conversion with all favorable advantages of three-level switching retained. Despite their proven buck-boost capability, existing three-level Z-source inverters are either too costly with...... numerous passive LC elements needed or poor in spectral quality if the "reduced element count" (REC) variant is used. Instead of being constrained by the tradeoff, this paper proposes an alternative three-level Z-source topological and control combination that can produce optimal output waveform quality......, while using lesser passive LC elements. Through detailed operational analysis, new operating modes of the REC Z-source inverters are identified, which when inserted appropriately to the inverter state sequence, will always produce the desired voltage transfer gain with minimized commutation count and...
Aalborg Inverter - A New Type of “Buck in Buck, Boost in Boost” Grid-Tied Inverter
DEFF Research Database (Denmark)
Wu, Weimin; Ji, Junhao; Blaabjerg, Frede
2015-01-01
is larger than the magnitude of the ac voltage, it is a voltage-source inverter, and on the contrary it is current-source inverter in the other mode. A 220 V/50 Hz/ 2000 W prototype has been constructed. Simulations and experiments show that it has a good control and system performance....
Aalborg Inverter - A new type of “Buck in Buck, Boost in Boost” Grid-tied Inverter
DEFF Research Database (Denmark)
Wu, Weimin; Blaabjerg, Frede
2013-01-01
This paper presents a new family of high efficiency DC/AC grid-tied inverter with a wide variation of input DC voltage. It is a kind of “Boost in Boost, Buck in Buck” inverter, meaning that only one power stage works at the high frequency to achieve the minimum switching loss. Furthermore, the mi...... the analysis on the equivalent circuits of a “three-level” single-phase inverter. Simulations show it has good control performance.......This paper presents a new family of high efficiency DC/AC grid-tied inverter with a wide variation of input DC voltage. It is a kind of “Boost in Boost, Buck in Buck” inverter, meaning that only one power stage works at the high frequency to achieve the minimum switching loss. Furthermore...
Dual Z-Source Inverter With Three-Level Reduced Common-Mode Switching
DEFF Research Database (Denmark)
Gao, Feng; Loh, Poh Chiang; Blaabjerg, Frede;
2007-01-01
This paper presents the design of a dual Z-source inverter that can be used with either a single dc source or two isolated dc sources. Unlike traditional inverters, the integration of a properly designed Z-source network and semiconductor switches to the proposed dual inverter allows buck......-boost power conversion to be performed over a wide modulation range, with three-level output waveforms generated. The connection of an additional transformer to the inverter ac output also allows all generic wye-or delta-connected loads with three-wire or four-wire configuration to be supplied by the inverter....... Modulationwise, the dual inverter can be controlled using a carefully designed carrier-based pulsewidth-modulation (PWM) scheme that will always ensure balanced voltage boosting of the Z-source network while simultaneously achieving reduced common-mode switching. Because of the omission of dead-time delays...
Institute of Scientific and Technical Information of China (English)
吴春华; 徐坤; 黄建明; 杨宇; 许富强
2011-01-01
The working principle, working mode and impedance transformation of photovoltaic distributed maximum power point tracking ( MPPT) based on non-inverting buck-boost converter are analyzed. The essence of MPPT is elaborated in detail from the perspective of the load impedance matching and a MPPT control strategy for non-inverting buck-boost converter is proposed in this paper. The algorithm can select different working mode automatically in order to make system working at maximum power point. The experimental results verify the feasibility and efficiency of the algorithm.%分析了基于非反相Buck-Boost变换器光伏分布式MPPT的工作原理、工作模式及其阻抗变换特性,从负载阻抗匹配的角度阐述了最大功率点跟踪的实质,并在此基础上提出了用于非反相Buck-Boost变换器的最大功率点跟踪控制策略,此算法能够自适应地选择不同的工作模式,使系统始终工作在最大功率点,实验结果验证了该算法的可行性和有效性.
Fault-tolerant three-level inverter
Edwards, John; Xu, Longya; Bhargava, Brij B.
2006-12-05
A method for driving a neutral point clamped three-level inverter is provided. In one exemplary embodiment, DC current is received at a neutral point-clamped three-level inverter. The inverter has a plurality of nodes including first, second and third output nodes. The inverter also has a plurality of switches. Faults are checked for in the inverter and predetermined switches are automatically activated responsive to a detected fault such that three-phase electrical power is provided at the output nodes.
Research on a Three-Phase DC/AC Inverter Based on Buck-Boost Circuit%基于升降压斩波电路的三相DC/AC逆变器研究
Institute of Scientific and Technical Information of China (English)
陈荣
2013-01-01
In order to solve the problems brought about by the common inverter,we propose a novel three-phase DC/AC inverter topology based on buck-boost circuit,and describes how it works.The implementation method applied for three-phase DC/AC inverter using single phase inverter is given.The single-phase inverter and threephase inverter are studied using PSIM software.The parameters adopted in the realistic simulation,waveforms such as load current,voltage of modulation reference and load were given.The simulation results proved that adopting the three-phase DC/AC inverter could achieve a good performance with wide input voltage range and the output voltage of it can gain a line frequency as 50 Hz and the correctness of theoretical analysis.%为了解决常用的逆变器所带来的问题,我们提出一种新型的带升降压功能的三相DC/AC变换器拓扑,并介绍了其工作原理.借助于PSIM仿真软件,对单相和三相电路进行了仿真研究,提出了由单相组成三相电压输出的构成方法.在列出仿真参数的前提下,给出了负载电压,负载电流以及调制给定电压和逆变器输出电压的仿真结果.仿真结果表明三相DC/AC逆变器可以实现50 kHz高频功率变换下宽输入电压范围工频逆变输出,证明了理论分析的正确性.
Chien-Wei Ma; Jaw-Kuen Shiau
2013-01-01
This paper analyzes and simulates the Li-ion battery charging process for a solar powered battery management system. The battery is charged using a non-inverting synchronous buck-boost DC/DC power converter. The system operates in buck, buck-boost, or boost mode, according to the supply voltage conditions from the solar panels. Rapid changes in atmospheric conditions or sunlight incident angle cause supply voltage variations. This study develops an electrochemical-based equivalent circuit mod...
DEFF Research Database (Denmark)
Goh, Ailian; Gao, Feng; Loh, Pon Chiang;
2007-01-01
control, and push up the overall system costs. Therefore, alternative topological solutions are of interest, and should preferably be implemented using only passive LC elements and diodes, connected as unique impedance networks. A number of possible network configurations are now investigated...... in this paper, and are respectively named as Z-source, H-source, EZ-source and their respective "inverted" variants. The presented impedance networks can either be used with a traditional voltage-source or current-source inverter, and can either be powered by a voltage or current source. All impedance networks...... the practicalities and performances of the described impedance networks....
Trans-Z-source Neutral Point Clamped inverter
DEFF Research Database (Denmark)
Mo, W.; Loh, P. C.; Li, D.;
2012-01-01
Transformer based Z-source (trans-Z-source) inverters are recently proposed by extending the traditional Z-source inverter with higher buck-boost capability as well as reducing the passive components at the same time. Multi-Level Z-source inverters are single-stage topological solutions used for...... buck-boost energy conversion with all the favourable advantages of multi-level switching retained. This paper presents three-level trans-Z-source Neutral Point Clamped (NPC) inverter topology, which achieves both the advantages of trans-Z-source and three-level NPC inverter configuration. With proper...... modulation scheme, the three-level trans-Z-source inverter can function with minimum of six device commutations per half carrier cycle (same as the traditional buck NPC inverter), while maintaining to produce the designed volt-sec average and inductive voltage boosting at ac output terminals. The designed...
A new Zero Voltage Switching three-level NPC inverter
DEFF Research Database (Denmark)
He, Ning; Chen, Yenan; Xu, Dehong;
2015-01-01
A novel Zero Voltage Switching (ZVS) three-level NPC inverter topology using a new ZVS Space Vector Modulation (SVM) scheme is proposed. A detailed operation analysis of ZVS three-level NPC inverter is given. The ZVS condition of the proposed ZVS inverter is derived and it can be achieved of all...... switches in the proposed inverter, which include both the main switches and the auxiliary switches. The design of resonant circuits parameters is also provided. Finally the proposed circuit and ZVS SVM scheme are verified by experimental results and demonstrate a superior performance....
Γ-source Neutral Point Clamped Inverter
DEFF Research Database (Denmark)
Mo, Wei; Loh, Poh Chiang; Blaabjerg, Frede
Transformer based Z-source inverters are recently proposed to achieve promising buck-boost capability. They have improved higher buck-boost capability, smaller size and less components count over Z-source inverters. On the other hand, neutral point clamped inverters have less switching stress...... and better output performance comparing with traditional two-level inverters. Integrating these two types of configurations can help neutral point inverters achieve enhanced votlage buck-boost capability....
Trans-Z-source and Γ-Z-source neutral-point-clamped inverters
DEFF Research Database (Denmark)
Wei, Mo; Loh, Poh Chiang; Blaabjerg, Frede;
2015-01-01
Z-source neutral-point-clamped (NPC) inverters are earlier proposed for obtaining voltage buck-boost and three-level switching simultaneously. Their performances are, however, constrained by a trade-off between their input-to-output gain and modulation ratio. This trade-off can lead to high-volta...
Modeling and Simulation of Buck-Boost Converter with Voltage Feedback Control
Zhou Xuelian; He Qiang
2015-01-01
In order to design the control system, it is necessary to have an exact model of buck-boost converter. This paper put forward the transfer function model of buck-boost converter by the state-space average method. The open-loop transfer function model of uncompensated system is deduced according to the mathematic model of the buck-boost converter, the controller is designed according to frequency domain. The phase and magnitude margin of the open-loop system of the buck-boost converter with co...
Three-Level AC-DC-AC Z-Source Converter Using Reduced Passive Component Count
DEFF Research Database (Denmark)
Loh, Poh Chiang; Gao, Feng; Tan, Pee-Chin;
2009-01-01
This paper presents a three-level ac-dc-ac Z-source converter with output voltage buck-boost capability. The converter is implemented by connecting a low-cost front-end diode rectifier to a neutral-point-clamped inverter through a single X-shaped LC impedance network. The inverter is controlled......-second average at its output, while simultaneously achieving inductive voltage boosting by shooting through either an appropriately selected inverter phase-leg or two phase-legs being commanded simultaneously. More interestingly, these performance features are achieved with no increase in the number...
Nonlinear Phenomena in Buck-Boost Power Factor Correction Converter
Directory of Open Access Journals (Sweden)
Mehrnoosh Vatani
2013-01-01
Full Text Available Buck-Boost Power-Factor-Correction (PFC converter with Average-Current-Model (ACM control is a nonlinear circuit because of the multiplier using and large change in the duty cycle, so its stability analysis must be studied by nonlinear model. In this paper double averaging method is used for describing the model of this converter. By this model we would be able to explain the low frequency dynamics of the system and identify stability boundaries according to circuit parameters and also nonlinear phenomena of this converter are detected.
A TEG Efficiency Booster with Buck-Boost Conversion
Wu, Hongfei; Sun, Kai; Zhang, Junjun; Xing, Yan
2013-07-01
A thermoelectric generator (TEG) efficiency booster with buck-boost conversion and power management is proposed as a TEG battery power conditioner suitable for a wide TEG output voltage range. An inverse-coupled inductor is employed in the buck-boost converter, which is used to achieve smooth current with low ripple on both the TEG and battery sides. Furthermore, benefiting from the magnetic flux counteraction of the two windings on the coupled inductor, the core size and power losses of the filter inductor are reduced, which can achieve both high efficiency and high power density. A power management strategy is proposed for this power conditioning system, which involves maximum power point tracking (MPPT), battery voltage control, and battery current control. A control method is employed to ensure smooth switching among different working modes. A modified MPPT control algorithm with improved dynamic and steady-state characteristics is presented and applied to the TEG battery power conditioning system to maximize energy harvesting. A 500-W prototype has been built, and experimental tests carried out on it. The power efficiency of the prototype at full load is higher than 96%, and peak efficiency of 99% is attained.
Three-Level AC-DC-AC Z-Source Converter Using Reduced Passive Component Count
DEFF Research Database (Denmark)
Loh, Poh Chiang; Gao, Feng; Tan, Pee-Chin;
2007-01-01
This paper presents a three-level ac-dc-ac Z-source converter with output voltage buck-boost capability. The converter is implemented by connecting a low cost front-end diode rectifier to a neutral-point-clamped inverter through a single X-shaped LC impedance network. The inverter is controlled...... a low cost alternative to sensitive applications that need to ride-through frequent input voltage sags. For confirming the converter performance, experimental testing using a constructed laboratory prototype is performed with its captured results presented in a later section of the paper....
Buck-Buck- Boost Regulatr (B3R)
Mourra, Olivier; Fernandez, Arturo; Landstroem, Sven; Tonicello, Ferdinando
2011-10-01
In a satellite, the main function of a Power Conditioning Unit (PCU) is to manage the energy coming from several power sources (usually solar arrays and battery) and to deliver it continuously to the users in an appropriate form during the overall mission. The objective of this paper is to present an electronic switching DC-DC converter called Buck-Buck-Boost Regulator (B3R) that could be used as a modular and recurrent solution in a PCU for regulated or un- regulated 28Vsatellite power bus classes. The power conversion stages of the B3R topology are first described. Then theoretical equations and practical tests illustrate how the converter operates in term of power conversion, control loops performances and efficiency. The paper finally provides some examples of single point failure tolerant implementation using the B3R.
Modeling of SVM Diode Clamping Three-Level Inverter Connected to Grid
DEFF Research Database (Denmark)
Guo, Yougui; Zeng, Ping; Zhu, Jieqiong;
2011-01-01
PLECS is used to model the diode clamping three-level inverter connected to grid and good results are obtained. First the output voltage SVM is described for diode clamping three-level inverter with loads connected to Y. Then the output voltage SVM of diode clamping three-level inverter is simply...... very powerful tool to real power circuits and it is very easy to simulate them. They have also verified that SVM control strategy is feasible to control the diode clamping three-level inverter....
Modeling and Simulation of Buck-Boost Converter with Voltage Feedback Control
Directory of Open Access Journals (Sweden)
Zhou Xuelian
2015-01-01
Full Text Available In order to design the control system, it is necessary to have an exact model of buck-boost converter. This paper put forward the transfer function model of buck-boost converter by the state-space average method. The open-loop transfer function model of uncompensated system is deduced according to the mathematic model of the buck-boost converter, the controller is designed according to frequency domain. The phase and magnitude margin of the open-loop system of the buck-boost converter with compensator have both been increased. After compensating, this control system has the advantages of small overshoot and short settling time. It can also improve control system’s real time property and anti-interference ability.
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...
Design and comparison of three-level three-phase T-source inverters
DEFF Research Database (Denmark)
Shults, T.; Husev, Oleksandr; Blaabjerg, Frede
2015-01-01
This paper presents guidelines for component design of recently proposed topologies of the three-level three-phase T-source inverters. Two different topologies are considered: T-source inverters with discontinuous input current and T-source inverters with continuous input current. Steady state...
Performance Evaluation of Three-Level Z-Source Inverters Under Semiconductor-Failure Conditions
DEFF Research Database (Denmark)
Gao, Feng; Loh, Poh Chiang; Blaabjerg, Frede;
2009-01-01
This paper evaluates and proposes various compensation methods for three-level Z-source inverters under semiconductor-failure conditions. Unlike the fault-tolerant techniques used in traditional three-level inverters, where either an extra phase-leg or collective switching states are used...... under semiconductor-failure conditions. For verifying these described performance features, PLECS simulation and experimental testing were performed with some results captured and shown in a later section for visual confirmation....
Performance Evaluation of Three-Level Z-Source Inverters Under Semiconductor Failure Conditions
DEFF Research Database (Denmark)
Gao, Feng; Loh, P.C.; Vilathgamuwa, D.M.;
2007-01-01
This paper proposes various compensation methods for three-level Z-source inverters under semiconductor failure conditions. Unlike the traditional fault tolerant techniques in three-level inverter by using either an additional phase-leg or collective switching states, the proposed methods simply...... reconfigure the gating signals in order to tolerate the failed semiconductor devices without significantly decreasing the ac output quality and amplitude by properly using the inherent boost characteristic of Z-source network. In addition, the Z-source dual inverters can maintain the zero common mode voltage...
Three Level Diode Clamped Inverter Fed Induction Motor with Dtc-Svm
Directory of Open Access Journals (Sweden)
V. Ranjith Kumar
2013-09-01
Full Text Available This project presents a three-level diode-clamped inverter feeding an asynchronous motor drive with direct torque control (DTC. The control method is based on DTC operating principles. The stator voltage vector reference is computed from the stator flux and torque errors imposed by the flux and torque controllers. This voltage reference is then generated using a diode-clamped inverter, where each phase of the inverter can be implemented using a dc source, which would be available from fuel cells, batteries, or ultra capacitors. This inverter provides nearly sinusoidal voltages with very low distortion, even without filtering, using fewer switching devices. In addition, the multilevel inverter can generate a high and fixed switching frequency output voltage with fewer switching losses, since only the small power cells of the inverter operate at a high switching rate. Therefore, a high performance and also efficient torque and flux controllers are obtained, enabling a DTC solution for multilevel-inverter-powered motor drives. The Pulse Width modulation technique for an inverter permits to obtain three phase system voltages, which can be applied to the controlled output. Space Vector Modulation (SVPWM principle differs from other PWM processes in the fact that all three drive signals for the inverter will be created simultaneously. The implementation of SVPWM process in digital systems necessitates less operation time and also less program memory. This project uses SVPWM technique for generation of pulses for three-level diode clamped inverter. Simulation is carried out on MATLAB-Simulink software.
An Effective Wind Energy System based on Buck-boost Controller
Directory of Open Access Journals (Sweden)
N. Prakash
2013-06-01
Full Text Available In Domestic Wind Machines, if the wind speed is low, the output voltage is not sufficient to charge the battery as it is lower than the rated charging voltage of the battery. This limits the overall efficiency of the Wind Machine to 20%. This study proposed to design and develop a Buck Boost Controller for the effective utilization of the wind machine. By implementing a controller based Buck Boost converter, the voltage produced at the lower wind speeds can also be utilized effectively by boosting it to the rated charging voltage of the battery. Also if the wind speed is high (>14 m/s, the DC output voltage will increase to more than 65 V. The converter bucks this high voltage to the nominal battery charging voltage (52 V, thereby protecting the battery from over charging voltage. Thus the effective utilization of the wind machine has been achieved by the use of the proposed Buck Boost Controller.
Modeling and Analysis of Transformerless High Gain Buck-boost DC-DC Converters
Directory of Open Access Journals (Sweden)
Vu Tran
2014-12-01
Full Text Available This paper proposes a transfomerless switched capacitor buck boost converter model, which provides higher voltage gain and higher efficiency when compared to the conventional buck boost converter. The averaged model based on state-space description is analyzed in the paper. The simulation results are presented to confirm the capability of the converter to generate high voltage ratios. The comparison between the proposed model and the traditional model is also provided to reveal the improvement. The proposed converter is suitable for for a wide application which requires high step-up DC-DC converters such as DC micro-grids and solar electrical energy.
Development of TMS320F2810 DSP Based Bidirectional buck-boost Chopper
Mr. K.S. Chakradhar*1,; M.Ayesha siddiqa2; T.Vandhana3
2014-01-01
A DC - DC converter is an electronic circuit which converts a source of direct current (DC) from one voltage level to another. It is a class of power converter. One common application of DC - DC converters is DC motor control. The Buck - Boost Chopper is a type of DC - DC converter. They are static devices which are used to obtain variable DC voltage from the source of constant DC voltage. Besides the saving in power, Buck-Boost choppers offer greater efficiency, faster respon...
BLDCM Control System Based on Buck-Boost Converter%基于Buck-Boost变换器驱动的无刷直流电动机控制系统
Institute of Scientific and Technical Information of China (English)
孟武胜; 王波; 何博
2011-01-01
An improved topology of brushless DC motor drive with a Buck-Boost converter before 3 phase inverter,The motor can be controlled by technique-multi-loop. This method can reduce switching losses,the inverter size and cost. Effectiveness and feasibility of the proposed control method was verified by MATLAB/Simulink.%提出在无刷直流电动机的驱动三相逆变桥的输入端加前级降压-升压(Buck-Boost)变换器,采用转速和直流母线电流的多环反馈控制方法实现电机的控制.该方法减少了开关损耗,逆变器尺寸和成本.通过MAT-LAB/Simulink仿真验证了该方法的有效性和可行性.
Directory of Open Access Journals (Sweden)
Jaw-Kuen Shiau
2014-08-01
Full Text Available The power converter is one of the essential elements for effective use of renewable power sources. This paper focuses on the development of a circuit simulation model for maximum power point tracking (MPPT evaluation of solar power that involves using different buck-boost power converter topologies; including SEPIC, Zeta, and four-switch type buck-boost DC/DC converters. The circuit simulation model mainly includes three subsystems: a PV model; a buck-boost converter-based MPPT system; and a fuzzy logic MPPT controller. Dynamic analyses of the current-fed buck-boost converter systems are conducted and results are presented in the paper. The maximum power point tracking function is achieved through appropriate control of the power switches of the power converter. A fuzzy logic controller is developed to perform the MPPT function for obtaining maximum power from the PV panel. The MATLAB-based Simulink piecewise linear electric circuit simulation tool is used to verify the complete circuit simulation model.
Analisys of Current-Bidirectional Buck-Boost Based Automotive Switch-Mode Audio Amplifier
DEFF Research Database (Denmark)
Bolten Maizonave, Gert; Andersen, Michael A. E.; Kjærgaard, Claus;
2011-01-01
The following study was carried out in order to assess quantitatively the performance of the buck-boost converter when used as switch-mode audio amplifier. It comprises of, to begin with, the delimitation of design criteria based on the state-ofthe- art solution, which is based in a differential ...
Control of Grid Connected Photovoltaic System Using Three-Level T-Type Inverter
Zorig, Abdelmalik; Belkeiri, Mohammed; Barkat, Said; Rabhi, Abdelhamid
2016-08-01
Three-level T-Type inverter (3LT2I) topology has numerous advantageous compared to three-level neutral-point-clamped (NPC) inverter. The main benefits of 3LT2I inverter are the efficiency, inverter cost, switching losses, and the quality of output voltage waveforms. In this paper, a photovoltaic distributed generation system based on dual-stage topology of DC-DC boost converter and 3LT2I is introduced. To that end, a decoupling control strategy of 3LT2I is proposed to control the current injected into the grid, reactive power compensation, and DC-link voltage. The resulting system is able to extract the maximum power from photovoltaic generator, to achieve sinusoidal grid currents, and to ensure reactive power compensation. The voltage-balancing control of two split DC capacitors of the 3LT2I is achieved using three-level space vector modulation with balancing strategy based on the effective use of the redundant switching states of the inverter voltage vectors. The proposed system performance is investigated at different operating conditions.
Directory of Open Access Journals (Sweden)
S. Sengottaian
2015-08-01
Full Text Available This study deals with a five phase three level Neutral Point Clamped (NPC inverter fed PMSM drive application. The motor performances depend upon mathematical model so the parameters vary are: noise, common mode voltage, flux variation and harmonic levels of the inverter or motor. Voltage saturation is one of the major problems of a motor which occurs due to speed oscillations, more current fluctuations. This problem can be solved by using PWM technique depends on the reference motor torque and flux. In this study Indirect Field Oriented Control (IFOC NPC inverter is suggested to reduce the voltage saturation. The three level neutral point clamped inverter is widely used for medium and high level applications. Compared with standard two level inverter, this type of NPC inverters have more merits. It generates greater number of levels output waveform in lower harmonic content at the same switching frequency and less voltage stress across the semiconductor switches; finally motor performance and control schemes are verified by using MATLAB/SIMULINK.
Modelling and Simulation of Three Level Inverters for Main Drive of the Plate Mill Rolling Stand
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Gasiyarov Vadim R.
2016-01-01
Full Text Available This paper addresses a modelling and a simulation of three level inverters for main drive of the plate mill rolling stand. The main purpose of the article is to develop of a mathematical description of the three level voltage source inverter based on a space vector pulse width modulation and to simulate a consumption current by the main electric drive based on 18-pulse rectification circuit. A twelve-megawatt synchronous motor as a load has been used. The modelling results were simulated at the Matlab/Simulink program. It can allow us to estimate an electromagnetic compatibility of the main electric drive based on transients of the consumption current. The research results can be used to assess the electromagnetic compatibility of powerful three level natural point clamped converters with different types of the space vector pulse width modulation on a load or a grid.
An Efficient Single Impedance Network Three Level Z-Source Neutral Point Clamped Inverter
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C.L.Kuppuswamy
2012-07-01
Full Text Available A multilevel inverter can eliminate the need for the step-up transformer and reduce the harmonics produced by the inverter. Although the multilevel inverter structure was initially introduced as a means of reducing the output waveform harmonic content, it was found that the dc bus voltage could be increased beyond the voltage rating of an individual power device by the use of a voltage clamping network consisting of diodes. By using voltage clamping techniques, the system KV rating can be extended beyond limits of an individual device. This paper presents Impedance (Z Source Neutral Point Clamped (NPC three level inverter with reduced number of impedance source networks and clamping diodes for non-linear loads. Earlier for a three level NPC inverter two separate impedance networks were used. But to reduce the circuit complexity without compromising with output requirement; only one impedance network is used and to substantiate this, the simulation of proposed circuit is carried out using MATLAB/Simulink for a 48 V input supply. A prototype is developed for an input voltage of 26V and the experimental results for the same are presented in this paper.
Neutral-point voltage dynamic model of three-level NPC inverter for reactive load
Maheshwari, Ramkrishan; Munk-Nielsen, Stig; Busquets Monge, Sergio
2012-01-01
A three-level neutral-point-c1amped inverter needs a controller for the neutral-point voltage. Typically, the controller design is based on a dynamic model. The dynamic model of the neutral-point voltage depends on the pulse width modulation technique used for the inverter. A pulse width modulation strategy which allows modeling the neutral-point voltage as a first-order continuous function is proposed in this paper. The new model shows that the neutral-point current is p...
Buck-Boost/Forward Hybrid Converter for PV Energy Conversion Applications
Sheng-Yu Tseng; Chien-Chih Chen; Hung-Yuan Wang
2014-01-01
This paper presents a charger and LED lighting (discharger) hybrid system with a PV array as its power source for electronic sign indicator applications. The charger adopts buck-boost converter which is operated in constant current mode to charge lead-acid battery and with the perturb and observe method to extract maximum power of PV arrays. Their control algorithms are implemented by microcontroller. Moreover, forward converter with active clamp circuit is operated in voltage regulation cond...
DEFF Research Database (Denmark)
Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.
2011-01-01
In this paper, a circuit-level decoupling modulation strategy is proposed for the three-level (TL) neutral-point-clamped (NPC) inverters. With the proposed modulation scheme, the TL-NPC inverter can be decoupled into two three-level Buck converters in each defined operating section, which makes...... without any feedback control. The simulation results show the validity of theoretical analysis....
Directory of Open Access Journals (Sweden)
S. Radha Krishna Reddy
2012-06-01
Full Text Available Multilevel inverters are increasingly being used in high-power medium voltage applications due to their superior performance compared to two-level inverters. Among various modulation techniques for a multilevel inverter, the space vector pulse width modulation (SVPWM is widely used. This paper deals with the three-phase three-level inverter fed induction motor drive. The proposed scheme deals with the development and implementation of three phase three level inverter to improve the efficiency and reliability of the inverter. Simulation tests have been carried out to examine the operating characteristics of the completed three-phase three-level inverter driving induction motor and an RL load with different switching devices and are compared
Direct Torque Control for Three-Level Neutral Point Clamped Inverter-Fed Induction Motor Drive
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M. K. Sahu
2012-04-01
Full Text Available Direct torque control (DTC is a control technique in AC drive systems to obtain high performance torque control. The classical DTC drive contains a pair of hysteresis comparators and suffers from variable switching frequency and high torque ripple. These problems can be solved by using space vector depending on the reference torque and flux. In this paper the space vector modulation technique is applied to the three-level Neutral Point Clamped (NPC inverter control in the proposed DTC-based induction motor drive system, resulting to a significant reduce of torque ripple. Three-level neutral point clamped inverters have been widely used in medium voltage applications. This type of inverters have several advantages over standard two-level VSI, such as greater number of levels in the output voltage waveforms, less harmonic distortion in voltage and current waveforms and lower switching frequencies. This paper emphasizes the derivation of switching states using the Space Vector Pulse Width Modulation (SVPWM technique. The control scheme is implemented using Matlab/Simulink. Experimental results using dSPACE validate the steady-state and the dynamic performance of the proposed control strategy.
Directory of Open Access Journals (Sweden)
Sreedhar Madichetty
2014-02-01
Full Text Available In this paper it proposes a high efficient soft-switching scheme based on zero-voltage-switching (ZVS and zero-current-switching(ZCS principle operated with a simple auxiliary circuit extended range for the front-end isolated DC-AC-DC-AC high power converter with an three phase three level diode clamped multi level inverter by using Minority Charge Carrier inspired optimization technique (MCI with Total Harmonic Distortion(THD,Switching losses, Selective harmonic elimination maintaining with its fundamental as an objective function. Input to the inverter is obtained by the photo voltaic cells and with battery bank. The switching scheme is optimized by MCI technique, analyzed and executed in Matlab and implemented with a digital signal processor (DSP .Experimental results with different loads have observed and shows its effectives, robustness of the applied technique.
Comparative Analysis of PWM Techniques for Three Level Diode Clamped Voltage Source Inverter
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Zulkifilie Bin Ibrahim
2014-07-01
Full Text Available Multilevel inverters are increasingly being used in high-power medium voltage industrial drive applications due to their superior performance compared to conventional two-level inverters. Thre are a number of Pulse width modulation (PWM techniques applied in recent years. The most widely applied PWM techniques are Sine Pulse Width Modulation (SPWM and Space Vector Pulse Width Modulation (SVPWM. SPWM is the most simple modulation technique that can realize easily in analog circuit. However, it has some drawbacks such as higher total harmonic distortion (THD, lower effective DC utilization and lower switching frequency. Space vector pulse width modulation (SVPWM is widely used because of their easier digital realization and better DC bus utilization and lower THD. The complexity is due to the difficulty in determining the reference vector location, on times calculation, and switching states selection. This paper presents a simple SVPWM algorithm for diode clamped three level inverters based on standard two-level SVPWM which can easily determine the location of reference vector, calculate the on-times, the selection of switching states. Three level diode clamped inverter (3LDCI using space vector modulation technique has been modeled and simulated using MATLAB/SIMULINK and Origin 6.1 with a passive R-L load that can be extended to any level. Simulation results are presented to verify the proposed SVPWM control in terms of THD. The results are compared with conventional sinusoidal pulse width modulation (SPWM where SVPWM shows better performance than SPWM in terms of THD.
Modeling of Busbars in High Power Neutral Point Clamped Three-Level Inverters
Institute of Scientific and Technical Information of China (English)
YI Rung; ZHAO Zhengming; ZHONG Yulin
2008-01-01
The busbars in high power neutral point clamped three-level inverters are modeled using the Maxwell Q3D Extractor software, which is based on the partial element equivalent circuits method. The equivalent circuits of the busbars and devices model are simulated in the electric simulator PSIM to analyze the effects of the parasitic inductance on the switching characteristics of the integrated gate commutatedthyristor (IGCT) in different topology positions. The simulation results agree well with the measured imped-ance analyzer results and the IGCT test results, which proves the effectiveness of the modeling method for the large, complex busbars.
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...
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...... PWM with synchronous smooth pulses-ratio changing and a quarter-wave symmetry of the voltage waveforms. Three basic versions of both algebraic and trigonometric synchronised PWM have been analysed. Simulations give the behaviour of the proposed methods and show some advantage of synchronised PWM...
Space vector modulation strategy for neutral-point voltage balancing in three-level inverter systems
DEFF Research Database (Denmark)
Choi, Uimin; Lee, Kyo Beum
2013-01-01
This study proposes a space vector modulation (SVM) strategy to balance the neutral-point voltage of three-level inverter systems. The proposed method is implemented by combining conventional symmetric SVM with nearest three-vector (NTV) modulation. The conventional SVM is converted to NTV...... modulation by properly adding or subtracting a minimum gate-on time. In addition, using this method, the switching frequency is reduced and a decrease of switching loss would be yielded. The neutral-point voltage is balanced by the proposed SVM strategy without additional hardware or complex calculations...
Saswati Swapna Dash; Byamakesh Nayak
2015-01-01
This paper proposes buck-boost capabilities of four quadrant chopper for wide range speed control of DC motor drives using symmetrical impedance network called Z-source network. By controlling the shoot through duty ratio from 0 to 0.5 and non-shoot through techniques, the Z-source four quadrant choppers can produce any desired DC voltage across the DC motor. The switching patterns for both buck and boost operations are presented to achieve four modes of operation of DC motor. As a result, th...
Evaluation of Arm Processor-based Bionic Intelligent Controller for a Buck-boost Converte
Directory of Open Access Journals (Sweden)
M.V. Mini
2015-07-01
Full Text Available This study focuses on performance-comparison of different tuning methods for a PI controller applied to a buck-boost converter. Comparison between the controllers is made by analysis of design methodology implementation issues and empirically measured performance. Design of PI controller is based on frequency response of the converter. The optimization of PI controller is based on ant colony algorithm. Experimental results show that, tuning the PI controller using ACO algorithm gave better performance than the conventional algorithm. This is mainly due to the fact ACO is capable of reducing the overshoot without oscillation.
High-accuracy current sensing circuit with current compensation technique for buck-boost converter
Rao, Yuan; Deng, Wan-Ling; Huang, Jun-Kai
2015-03-01
A novel on-chip current sensing circuit with current compensation technique suitable for buck-boost converter is presented in this article. The proposed technique can sense the full-range inductor current with high accuracy and high speed. It is mainly based on matched current mirror and does not require a large proportion of aspect ratio between the powerFET and the senseFET, thus it reduces the complexity of circuit design and the layout mismatch issue without decreasing the power efficiency. The circuit is fabricated with TSMC 0.25 µm 2P5M mixed-signal process. Simulation results show that the buck-boost converter can be operated at 200 kHz to 4 MHz switching frequency with an input voltage from 2.8 to 4.7 V. The output voltage is 3.6 V, and the maximum accuracy for both high and low side sensing current reaches 99% within the load current ranging from 200 to 600 mA.
Study on Nonlinear Phenomena in Buck-Boost Converter with Switched-Inductor Structure
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Hongchen Liu
2013-01-01
Full Text Available The switched-inductor structure can be inserted into a traditional Buck-Boost converter to get a high voltage conversion ratio. Nonlinear phenomena may occur in this new converter, which might well lead the system to be unstable. In this paper, a discrete iterated mapping model is established when the new Buck-Boost converter is working at continuous conduction current-controlled mode. On the basis of the discrete model, the bifurcation diagrams and Poincare sections are drawn and then used to analyze the effects of the circuit parameters on the performances. It can be seen clearly that various kinds of nonlinear phenomena are easy to occur in this new converter, including period-doubling bifurcation, border collision bifurcation, tangent bifurcation, and intermittent chaos. Value range of the circuit parameters that may cause bifurcations and chaos are also discussed. Finally, the time-domain waveforms, phase portraits, and power spectrum are obtained by using Matlab/Simulink, which validates the theoretical analysis results.
Asymmetrical Γ-Source Inverters
DEFF Research Database (Denmark)
Wei, Mo; Poh Chiang, Loh; Blaabjerg, Frede
2014-01-01
Impedance-source inverters are inverters with voltage-buck-boost capability that cannot be achieved by the traditional inverters. Their boost capability is introduced by shorting their phase legs without causing damages. Impedance-source inverters are therefore less prone to false triggering caus...... current drawn by the proposed inverters is smoother and, hence, more adaptable by the source. Theories and experimental results have been presented in this paper for validating the concepts proposed....
DEFF Research Database (Denmark)
Mira Albert, Maria del Carmen; Zhang, Zhe; Knott, Arnold;
2015-01-01
DC microgrids or nanogrids have attracted increasing research interest in recent years. Therefore, as a critical component, dc-dc converters with multiple inputs are required. In this paper, a dual-input interleaved buck/boost converter is proposed and its corresponding power flow control methods...
Phase Angle Control of Three Level Inverter Based D-STATCOM Using Neuro-Fuzzy Controller
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COTELI, R.
2012-02-01
Full Text Available Distribution Static Compensator (D-STATCOM is a shunt compensation device used to improve electric power quality in distribution systems. It is well-known that D-STATCOM is a nonlinear, semi-defined and time-varying system. Therefore, control of D-STATCOM by the conventional control techniques is very difficult task. In this paper, the control of D-STATCOM is carried out by the neuro-fuzzy controller (NFC which has non-linear and robust structure. For this aim, an experimental setup based on three-level H-bridge inverter is constructed. Phase angle control method is used for control of D-STATCOM's output reactive power. Control algorithm for this experimental setup is prepared in MATLAB/Simulink and downloaded to DS1103 controller card. A Mamdani type NFC is designed for control of D-STATCOM's reactive current. Output of NFC is integrated to increase tracking performance of controller in steady state. The performance of D-STATCOM is experimentally evaluated by changing reference reactive current as on-line. The experimental results show that the proposed controller gives very satisfactory performance under different loading conditions.
DEFF Research Database (Denmark)
Choi, Uimin; Lee, K.B.; Lee, Hyun-Hee
2013-01-01
This paper proposes a neutral-point voltage balancing method for a three-level inverter that uses discontinuous pulse width modulation (DPWM). The performance of a three-level inverter system is affected by the neutral-point voltage unbalancing. Therefore, the voltages of series connected dc...... is implemented by adjusting the discontinuous pulsewidth of positive and negative cycle. The proposed method maintains low switching losses and achieves the effective voltage balancing, without additional hardware and complex calculations. Simulation and experimental results confirm the feasibility...
Directory of Open Access Journals (Sweden)
Saswati Swapna Dash
2015-02-01
Full Text Available This paper proposes buck-boost capabilities of four quadrant chopper for wide range speed control of DC motor drives using symmetrical impedance network called Z-source network. By controlling the shoot through duty ratio from 0 to 0.5 and non-shoot through techniques, the Z-source four quadrant choppers can produce any desired DC voltage across the DC motor. The switching patterns for both buck and boost operations are presented to achieve four modes of operation of DC motor. As a result, the proposed model will have ride through capability during voltage sags, manage during voltage swells, used in any types of DC voltage sources such as fuel cell and solar cell and improve the reliability by reducing EMI noise. Analysis and simulation results are presented to demonstrate these new findings.
On the maximum regulation range in boost and buck-boost converters
Ninomiya, T.; Harada, K.; Nakahara, M.
Two types of instability conditions in boost and buck-boost converters with a feedback loop are analyzed by means of the steady-state characteristic and dynamic small-signal modeling. Type I instability involves a drastic voltage drop, and in Type II instability, a limit-cycle oscillation arises and the output voltage oscillates at low frequencies. The maximum regulation range is derived analytically for the load variation and verified experimentally. For high feedback gain, it is determined by the Type II instability condition, whereas for low feedback gain, it is determined by the Type I instability condition. Type II instability can be suppressed by decreasing the reactor inductance or by increasing the capacitance of a smoothing capacitor. However, Type I instability is found to be independent of these values.
DEFF Research Database (Denmark)
Panfilov, Dmitry; Husev, Oleksandr; Blaabjerg, Frede;
2016-01-01
This study compares a three-phase three-level voltage source inverter with an intermediate dc-dc boost converter and a quasi-Z-source inverter in terms of passive elements values and dimensions, semiconductor stresses, and overall efficiency. A comparative analysis was conducted with relative...... parameters to evaluate converter parameters for any application. The equations obtained were confirmed by simulation and experimental setup. Field of application has been discussed....
DEFF Research Database (Denmark)
Choi, Uimin; Lee, June-Seok; Lee, Kyo-Beum
2014-01-01
This paper proposes a new modulation strategy that balances the neutral-point voltage for three-level neutral-clamped inverter systems. The proposed modulation replaces the P-type or N-type small switching states with other switching states that do not affect the neutral-point voltage. The zero and...
DEFF Research Database (Denmark)
Ma, Ke; Blaabjerg, Frede
2016-01-01
This letter investigates the loss and thermal behaviors of a three-level neutral-point-clamped (3L-NPC) inverter undergoing moderate modulation index, which is typically presented during minor voltage sags of the power grid or speed changes of the electric machines. A series of new space vector m...
DEFF Research Database (Denmark)
Lee, Kyo-Beum; Huh, Sung-Hoe; Yoo, Ji-Yoon;
2005-01-01
A stable sensorless controller for DTC of induction motor fed by three-level inverter using the Radial Basis Function Network (RBFN) is presented in this paper. The torque ripple can be drastically reduced and low speed performance can be obtained in the DTC system for high performance induction...
Design of Three-Phase Three-Level CIC T-Source Inverter with Maximum Boost Control
DEFF Research Database (Denmark)
Shults, Tatiana; Husev, Oleksandr; Roncero-Clemente, Carlos;
2015-01-01
This paper presents guidelines for component design of the three-level three-phase T-source inverter with continuous input current under maximum boost control proposed recently. Steady state analysis under low-frequency current and voltage ripples in the dc side was made. Component sizes for both...
Comparison of the Impedance-Source Networks for Two and Multilevel Buck-Boost Inverter Applications
DEFF Research Database (Denmark)
Husev, Oleksandr; Blaabjerg, Frede; Roncero-Clemente, Carlos;
2016-01-01
Impedance-source networks are an increasingly popular solution in power converter applications, especially in single-stage buck–boost power conversion to avoid additional front-end dc–dc power converters. In the survey papers published, no analytical comparisons of different topologies have been ...
Reliability Improvement of a T-Type Three-Level Inverter With Fault-Tolerant Control Strategy
DEFF Research Database (Denmark)
Choi, Uimin; Blaabjerg, Frede; Lee, Kyo-Beum
2015-01-01
This paper proposes a fault-tolerant control strategy for a T-type three-level inverter when an open-circuit fault occurs. The proposed method is explained by dividing fault into two cases: the faulty condition of half-bridge switches and neutral-point switches. In case of the open-circuit fault...... in a neutral-point switch, two methods will be proposed and compared based on thermal analysis and neutral-point voltage oscillation. The reliability of T-type inverter systems is improved considerably by the proposed algorithm when a switch fails. The proposed method does not require any additional components...
Diagnosis and Tolerant Strategy of an Open-Switch Fault for T-type Three-Level Inverter Systems
DEFF Research Database (Denmark)
Choi, Uimin; Lee, Kyo Beum; Blaabjerg, Frede
2014-01-01
-tolerant strategy is explained by dividing into two cases: the faulty condition of half-bridge switches and the neutral-point switches. The performance of the T-type inverter system improves considerably by the proposed fault tolerant algorithm when a switch fails. The roposed method does not require additional......This paper proposes a new diagnosis method of an open-switch fault and fault-tolerant control strategy for T-type three-level inverter systems. The location of faulty switch can be identified by the average of normalized phase current and the change of the neutral-point voltage. The proposed fault...
Directory of Open Access Journals (Sweden)
Ningning Yang
2016-01-01
Full Text Available In recent days, fractional calculus (FC has been accepted as a novel modeling tool that can extend the descriptive power of the traditional calculus. Fractional-order descriptiveness can increase the flexibility and degrees of freedom of the model by means of fractional parameters. Based on the fact that real capacitors and inductors are “intrinsic” fractional order, fractional calculus is introduced into the modeling process to establish a fractional-order state-space averaging model of the Buck-Boost converter in pseudo-continuous conduction mode (PCCM. Orders of the model are considered as extra parameters, and these parameters have significant influences on the performance of the model. The inductor current, the inductor current ripple, the amplitude of the output voltage, and the transfer functions of the fractional-order model are all related to orders. The contrast simulation experiments are conducted to investigate the performance of integer-order and fractional-order Buck-Boost converters in PCCM. Results of numerical and circuit simulations demonstrate that the proposed theoretical analysis is effective; the fractional-order model of the Buck-Boost converter in PCCM has certain theoretical and practical significance for modeling and performance analysis of other electrical or electronic equipment.
Carrier-Based Common Mode Voltage Control Techniques in Three-Level Diode-Clamped Inverter
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Pradyumn Chaturvedi
2012-01-01
Full Text Available Switching converters are used in electric drive applications to produce variable voltage, variable frequency supply which generates harmful large dv/dt and high-frequency common mode voltages (CMV. Multilevel inverters generate lower CMV as compared to conventional two-level inverters. This paper presents simple carrier-based technique to control the common mode voltages in multilevel inverters using different structures of sine-triangle comparison method such as phase disposition (PD, phase opposition disposition (POD by adding common mode voltage offset signal to actual reference voltage signal. This paper also presented the method to optimize the magnitude of this offset signal to reduce CMV and total harmonic distortion in inverter output voltage. The presented techniques give comparable performance as obtained in complex space vector-based control strategy, in terms of number of commutations, magnitude, and rate of change of CMV and harmonic profile of inverter output voltage. Simulation and experimental results presented confirm the effectiveness of the proposed techniques to control the common mode voltages.
DEFF Research Database (Denmark)
Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, S.
2013-01-01
A Neutral-Point-Clamped (NPC) three-level inverter with small dc-link capacitors is presented in this paper. The inverter requires zero average neutral-point current for stable neutral-point voltage. The small dc-link capacitors may not maintain capacitor voltage balance, even with zero neutral......-point current. This may happen due to nonlinearities present in the circuit. This requires a fast control of the neutral-point voltage. A simple carrier based modulation strategy which allows modeling of the neutral-point voltage dynamics as a continuous function of power drawn from the inverter is proposed...... neutral-point voltage control on the basis of the continuous model. The design method for optimum performance is discussed. The implementation of the proposed modulation strategy and the controller is very simple. The controller is implemented in a 7.5 kW induction machine based drive with only 14 ìF dc...
A New Transformerless Single-Phase Buck-Boost AC Voltage Regulator
Directory of Open Access Journals (Sweden)
YALCIN, F.
2016-05-01
Full Text Available Voltage regulation is one of the important goals for electrical sources and consumers. In this paper a new transformerless single-phase AC voltage regulator based on buck-boost converter topology is presented. The regulator circuit has a simple structure using only two bidirectional active switches, one inductor and one capacitor. A closed loop control system is implemented for the proposed regulator operation. A control law depending on the instantaneous values of the regulator's real input and desired output voltage is obtained and supports the PI controller. The control law allows the controller to obtain efficient pulse width modulation (PWM switching duty ratio for the desired output voltage when the input voltage has surges or fluctuations and the output load is changed. An experimental laboratory setup has been implemented for the proposed AC voltage regulator. The obtained results demonstrate that the proposed topology is capable of and efficient for both bucking and boosting the input AC voltage to a high quality output voltage with a low total harmonic distortion (THD for different input voltage and load conditions.
Buck-Boost/Forward Hybrid Converter for PV Energy Conversion Applications
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Sheng-Yu Tseng
2014-01-01
Full Text Available This paper presents a charger and LED lighting (discharger hybrid system with a PV array as its power source for electronic sign indicator applications. The charger adopts buck-boost converter which is operated in constant current mode to charge lead-acid battery and with the perturb and observe method to extract maximum power of PV arrays. Their control algorithms are implemented by microcontroller. Moreover, forward converter with active clamp circuit is operated in voltage regulation condition to drive LED for electronic sign applications. To simplify the circuit structure of the proposed hybrid converter, switches of two converters are integrated with the switch integration technique. With this approach, the proposed hybrid converter has several merits, which are less component counts, lighter weight, smaller size, and higher conversion efficiency. Finally, a prototype of LED driving system under output voltage of 10 V and output power of 20 W has been implemented to verify its feasibility. It is suitable for the electronic sign indicator applications.
Birchenough, Arthur G.
2003-01-01
Improvements in the efficiency and size of DC-DC converters have resulted from advances in components, primarily semiconductors, and improved topologies. One topology, which has shown very high potential in limited applications, is the Series Connected Boost Unit (SCBU), wherein a small DC-DC converter output is connected in series with the input bus to provide an output voltage equal to or greater than the input voltage. Since the DC-DC converter switches only a fraction of the power throughput, the overall system efficiency is very high. But this technique is limited to applications where the output is always greater than the input. The Series Connected Buck Boost Regulator (SCBBR) concept extends partial power processing technique used in the SCBU to operation when the desired output voltage is higher or lower than the input voltage, and the implementation described can even operate as a conventional buck converter to operate at very low output to input voltage ratios. This paper describes the operation and performance of an SCBBR configured as a bus voltage regulator providing 50 percent voltage regulation range, bus switching, and overload limiting, operating above 98 percent efficiency. The technique does not provide input-output isolation.
DEFF Research Database (Denmark)
Anthon, Alexander; Zhang, Zhe; Andersen, Michael A. E.;
2016-01-01
. The first solution directly replaces the 1200 V primary Si IGBT switches with lower loss 1200 V SiC MOSFETs. The second solution strategically adds 600 V CoolMos FET devices to the conventional Si T-Type inverter to reduce the primary commutation losses. Semiconductor loss models, experimentally verified...
Neutral-point voltage dynamic model of three-level NPC inverter for reactive load
DEFF Research Database (Denmark)
Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, Sergio
2012-01-01
strategy which allows modeling the neutral-point voltage as a first-order continuous function is proposed in this paper. The new model shows that the neutral-point current is proportional to the reactive power drawn from the inverter. Since the model is a first-order model, a simple proportional controller...... is used in this paper to control the neutral-point voltage. Experimental results verifying the proposed modulation strategy and the controller are also presented in this paper....
Analysis and carrier-based modulation of Z-source NPC inverters
Dehghan, Seyed Mohammad; Mohamadian, Mustafa; Gharekhani, Reza
2012-08-01
Multi-level neutral-point-clamped (NPC) inverters are widely used in high and medium voltage applications. However, these inverters are only buck-type converters. Recently z-source NPC inverters have been proposed as the buck-boost three-level inverter. New inverters use a z-source network as the input stage. This article analyses the features and limitations of two main topologies of z-source NPC inverters (dual z-source network NPC inverter and single z-source network NPC inverter). The low-frequency ripple of the inductor current and the capacitor voltage of the z-source networks in the z-source NPC inverters are surveyed. This article also proposes two novel PWM methods for the z-source NPC inverters, which can be easily implemented experimentally. In the proposed methods, generated switching signals for the conventional NPC inverter are modified for the z-source NPC inverter using a simple logic circuit considering the boost factors and the power sharing ratio. The performance of the proposed simple PWM methods is verified by simulation and experimental results.
Institute of Scientific and Technical Information of China (English)
Jie ZHANG; Ryuichi YOKOYAMA; Jinhua SHE; Win WU
2013-01-01
One problem with a single source three-level inverter is the drafting of its neutral-point voltage. This may occur during transition or when unbalanced loads are connected to the inverter system. Variation of neutral-point voltage may greatly deteriorate the power quality. In this paper, we employ an equivalent-input-disturbance approach to deal with this problem. By adding an extra neutral leg, the control problem of neutral-point voltage is converted to a disturbance rejection problem. This method suppresses the variation of the neutral-point voltage to a low level and reduces the capacity of DC-link capacitors. Simulation results show the effectiveness of the method.
Draou, Azeddine
2012-12-01
This paper presents the dynamic performance analysis of an Advanced Static Var Compensator (ASVC) using three-level neutral point-clamped voltage source inverter. The paper presents the principles of operating and the method of reference currents generation. The dynamic behaviour of the system is further analysed using Matlab/Simulink with SimPower Systems toolbox through a set of simulation tests. The results obtained have been applied to an active power filter which might lead to the design of a robust controller for current harmonics and reactive power applications
Directory of Open Access Journals (Sweden)
Muhammad Taufiq Ramadhan
2015-03-01
Full Text Available Penggunaan mobil listrik secara umum terkendala pada beban, kecepatan aktual, serta efisiensi energi. Pemanfaatan Fuzzy Logic Controller untuk pengaturan kecepatan motor DC pada mobil listrik diperlukan untuk meraih kecepatan aktual yang lebih presisi sehingga diperoleh efisiensi energi. Selain itu perlu juga menggunakan Bidirectional Buck-Boost Cascade Converter untuk pengaturan motor DC secara bidirectional, yakni pengaturan saat motoring dan saat pengereman regeneratif (regenerative braking. Hal ini berdasar pada energi yang terbuang percuma, baik itu rugi elektris maupun rugi mekanis saat pengereman.
A tapped-inductor buck-boost converter for a multi-DEAP generator energy harvesting system
DEFF Research Database (Denmark)
Dimopoulos, Emmanouil; Munk-Nielsen, Stig
2014-01-01
Interest on Dielectric ElectroActive Polymer (DEAP) generators has aroused among scientists in recent years, due to the former ones' documented advantages against competing electromagnetic and field-activated technologies. Yet, the need for bidirectional energy flow under high step-up and high step...... the effective operational range of the power electronic converter. In this paper, a bidirectional tapped-inductor buck-boost converter is proposed, addressing high-efficient high step-up and high step-down voltage conversion ratios, for energy harvesting applications based on DEAP generators. The effective...
DEFF Research Database (Denmark)
Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, S.
2012-01-01
The size of passive components in an adjustable speed drive can be reduced by using small dc-link capacitors. The EMI filter in the drive also consists of passive components. The size of the filter can be reduced by using a three-level inverter, which can have low output voltage distortion. Howev....... Results show that the conducted emission from the three-level inverter is lower than that of the two-level inverter. Thus, a three-level inverter requires a smaller EMI filter in motor drives with small dc-link capacitors.......The size of passive components in an adjustable speed drive can be reduced by using small dc-link capacitors. The EMI filter in the drive also consists of passive components. The size of the filter can be reduced by using a three-level inverter, which can have low output voltage distortion. However......, the shaft voltage, and the conducted emission for the small dc-link capacitor based three-level inverter are compared with that of the two-level inverter operated with space vector PWM strategy. Experimental results for the common mode voltage, the shaft voltage, and the conducted emission are presented...
DEFF Research Database (Denmark)
Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.
2013-01-01
carrier wave needed for pulse width modulating. Same as a space vector modulation, the maximum modulation index, 1.1547, can be attainable by the proposed scheme. Moreover, compared to conventional continuous sinusoidal pulse width modulation, using this technique here the switching losses of the devices......A new pulse width modulation (PWM) strategy which is an alternative approach of discontinuous PWM (DPWM) for a three-level neutral point clamped (NPC) inverter is developed and presented in this paper. The proposed PWM scheme not only takes advantage of the special properties available in NPC...... can be reduced by one third. In order to explain the operation of this topology properly, the decoupling principle including the driving signal synthesis and the NP potential variation are analyzed in detail in this paper. Finally the viability and performance of the proposed modulation scheme...
Directory of Open Access Journals (Sweden)
Yap Hoon
2016-07-01
Full Text Available A new control technique known as inverted error deviation (IED control is incorporated into the main DC-link capacitor voltage regulation algorithm of a three-level neutral-point diode clamped (NPC inverter-based shunt active power filter (SAPF to enhance its performance in overall DC-link voltage regulation so as to improve its harmonics mitigation performances. In the SAPF controller, DC-link capacitor voltage regulation algorithms with either the proportional-integral (PI or fuzzy logic control (FLC technique have played a significant role in maintaining a constant DC-link voltage across the DC-link capacitors. However, both techniques are mostly operated based on a direct voltage error manipulation approach which is insufficient to address the severe DC-link voltage deviation that occurs during dynamic-state conditions. As a result, the conventional algorithms perform poorly with large overshoot, undershoot, and slow response time. Therefore, the IED control technique is proposed to precisely address the DC-link voltage deviation. To validate effectiveness and feasibility of the proposed algorithm, simulation work in MATLAB-Simulink and experimental implementation utilizing a TMS320F28335 Digital Signal Processor (DSP are performed. Moreover, conventional algorithms with PI and FLC techniques are tested too for comparison purposes. Both simulation and experimental results are presented, confirming the improvement achieved by the proposed algorithm in terms of accuracy and dynamic response in comparison to the conventional algorithms.
Li, Qing; Zhang, Xiao-ping; Chen, Qi
2011-12-01
The dynamic performance of a novel Buck-Boost matrix converter (BBMC) based on double-loop control strategy is put forward in this paper. The fundamental principle of BBMC has been elaborated and the method of the double-loop control strategy has been built with Matlab, and then the dynamic performances of BBMC based on the double-loop control strategy are discussed. The results show that the output voltage and frequency can be almost constant with the BBMC and double-loop control strategy despite of the changeable input voltage and frequency. Moreover, a high-quality sine output wave with low harmonic distortion can be directly obtained without filtering. So it can be drawn that the BBMC based on the double-loop control strategy has perfectly dynamic performance and practical importance to the engineering.
Shi-Zhou Xu; Feng-You He
2015-01-01
The high-power three-level explosion-proof inverters demand high thermal stability of power devices, and a set of theories and methods is needed to achieve an accurate power-loss calculation of power devices, to establish heat dissipation model, and ultimately to reduce the power loss to improve thermal stability of system. In this paper, the principle of neutral point clamped three-level (NPC3L) inverter is elaborated firstly, and a fourth-order RC equivalent circuit of IGBT is derived, on w...
Institute of Scientific and Technical Information of China (English)
赵犇; 马瑞卿
2015-01-01
An additional DC?DC converter is needed for traditional boost power factor correction ( PFC) converter to obtain low output voltage. When using buck type topology, the distortion of input current is large because no pow?er is transferred to output when gird voltage is lower than output voltage. Thus, the buck?boost type topology be?comes priority in the low output voltage application. Compared with the classic cascaded buck?boost PFC converter, the proposed single stage bridgeless buck?boost topology has lower semiconductors counts, and lower devices counts in the conduction loop which means less conduction losses. The tapped inductor is employed to achieve more attenu?ation. Thus, the proposed topology suits the low output voltage application very well. The One Cycle Control ( OCC) is adopted to achieve good dynamic performance and the elimination of multiplier can simplify the control circuit and reduce the cost. The simulated results and their analysis show preliminarily that:(1) the proposed topology is feasible and has the merits of simple structure and less conduction losses; ( 2 ) the power factor correction using OCC is reliable and has the advantages of low current distortion and high power factor.%传统的boost型功率因数校正变换器需要额外1级DC?DC变换器才能实现低电压输出,而buck型拓扑由于在电网电压低于输出电压时没有输入电流而导致电流畸变很大,因此buck?boost型拓扑就成为在低电压输出场合实现单级式功率因数校正的优先选择. 相较于经典的级联式buck?boost功率因数校正变换器,文中所提出的单级式无桥buck?boost拓扑所需的半导体器件数量更少,且导通回路中的功率器件个数也大大减小,从而可以降低导通损耗;加上引入了耦合电感提高了电压衰减率,因此特别适合低电压输出场合;采用了单周期控制作为功率因数校正的控制方法,具有更好的动态性能,而且电路实现中无需乘法
Directory of Open Access Journals (Sweden)
Shi-Zhou Xu
2015-01-01
Full Text Available The high-power three-level explosion-proof inverters demand high thermal stability of power devices, and a set of theories and methods is needed to achieve an accurate power-loss calculation of power devices, to establish heat dissipation model, and ultimately to reduce the power loss to improve thermal stability of system. In this paper, the principle of neutral point clamped three-level (NPC3L inverter is elaborated firstly, and a fourth-order RC equivalent circuit of IGBT is derived, on which basis the power-loss model of IGBT and the optimized maternal power-loss thermal model, using an optimized power-loss algorithm, are established. Secondly, in accordance with the optimized maternal power-loss thermal model, the generic formulas of power-loss calculation are deduced to calculate the power-loss modification values of NPC3L and soft switching three-level (S3L inverters, which will be the thermal sources during thermal analysis for maternal power-loss thermal models. Finally, the experiment conducted on the 2.1 MW experimental platform shows that S3L inverter has the same excellent output characteristics with NPC3L inverter, reduces the power loss significantly by 213 W in each half-bridge, and decreases the temperature by 10°C, coinciding with the theoretical calculation, which verifies the accuracy of optimized power-loss algorithm and the effectiveness of the improvement.
Demirbaş, Şevki; Fidanboy, Hikmet; Kurt, Erol
2016-08-01
In this paper, detailed analyses of the chaotic behavior observed in a buck-boost converter are presented. Although this basic converter system is already known world-wide for the purpose of dc-dc conversion of the output of renewable energy systems, it indicates certain chaotic regimes where both the output amplitude and frequency change randomly. This chaotic regime can yield an unstable output over the resistive or resistive/inductive electrical loads. This study presents a detailed map for the regular and chaotic regions in terms of material parameters, such as converter capacitance C, resistive load R, and inductive load L. Thus, the stable area of operation for efficient and renewable electricity production will be ascertained for the studied converter system. We emphasize that the material parameters C, R, and L play important roles in generating energy from the solar cell; indeed, the stability increases with higher values of the converter capacitor and load inductance, whereas it decreases according to the resistive load. A number of periodic windows have been observed and the output frequency gives a broad-band spectrum of up to 50 kHz.
A tapped-inductor buck-boost converter for a multi-DEAP generator energy harvesting system
Dimopoulos, Emmanouil; Munk-Nielsen, Stig
2014-03-01
Interest on Dielectric ElectroActive Polymer (DEAP) generators has aroused among scientists in recent years, due to the former ones' documented advantages against competing electromagnetic and field-activated technologies. Yet, the need for bidirectional energy flow under high step-up and high step-down voltage conversion ratios, accompanied by low-average but relatively high-peak currents, imposes great challenges on the design of the employed power electronic converter. On top of that, the shortage of commercially-available, high-efficient, high-voltage, low-power semiconductor devices limits the effective operational range of the power electronic converter. In this paper, a bidirectional tapped-inductor buck-boost converter is proposed, addressing high- efficient high step-up and high step-down voltage conversion ratios, for energy harvesting applications based on DEAP generators. The effective operational range of the converter is extended, by replacing its high-side switch with a string of three serialized MOSFETs, to accommodate the need for high-efficient high-voltage operation. Experiments conducted on a single DEAP generator - part of a quadruple DEAP generator energy harvesting system with all elements installed sequentially in the same circular disk with a 90° phase shift - validate the applicability of the proposed converter, demonstrating energy harvesting of 0.26 J, at 0.5 Hz and 60% delta- strain; characterized by an energy density of 1.25 J per kg of active material.
Directory of Open Access Journals (Sweden)
Jeevan Naik
2015-06-01
Full Text Available In this paper, a design and control for the buck-boost converter, i.e., 1-plus-D converter with a positive output voltage, is presented, which combines the 1-plus-D converter and the synchronous rectified (SR buck converter. By doing so, the problem in voltage bucking of the 1-plus-D converter can be solved, thereby increasing the application capability of the 1-plus-D converter. Since such a converter operates in continuous conduction mode inherently, it possesses the nonpulsating output current, thereby not only decreasing the current stress on the output capacitor but also reducing the output voltage ripple. Above all, both the 1-plus-D converter and the SR buck converter, combined into a buck–boost converter with no right-half plane zero, use the same power switches, thereby causing the required circuit to be compact and the corresponding cost to be down. Furthermore, during the magnetization period, the input voltage of the 1-plus-D converter comes from the input voltage source, whereas during the demagnetization period, the input voltage of the 1-plus-D converter comes from the output voltage of the SR buck converter.
DEFF Research Database (Denmark)
Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, S.
2012-01-01
strategy ensures zero average neutral-point current in a switching period. A newly proposed boundary compression is used to regulate the dc-link voltage at all operating points. A description of the algorithm to implement the modulation strategy is also presented. The main advantage of the proposed......In a voltage source inverter, overmodulation is required to extend the range of operation and enhance the dc-link voltage utilization. A carrier-based implementation of a modulation strategy for the three-level neutral-point-clamped inverter is proposed for the overmodulation region. The modulation...
Diagnosis method of an open-switch fault for a grid-connected T-type three-level inverter system
DEFF Research Database (Denmark)
Choi, U. M.; Lee, K. B.; Blaabjerg, Frede
2012-01-01
This paper proposes a diagnosis method of an open-switch fault and fault-tolerant control algorithm for a grid-connected T-type three-level inverter. The location of the faulty switch is identified by using the changes of average phase current and the neutral-point voltage. The fault-tolerant con......This paper proposes a diagnosis method of an open-switch fault and fault-tolerant control algorithm for a grid-connected T-type three-level inverter. The location of the faulty switch is identified by using the changes of average phase current and the neutral-point voltage. The fault......-tolerant control algorithm can be used when the open switch fault occurs in the middle switches. It is achieved by simply modifying the conventional SVM method. The proposed methods are advantageous as they do not require additional sensors and they do not involve complex calculations. Therefore, this method...
Chebabhi, Ali; Fellah, Mohammed Karim; Kessal, Abdelhalim; Benkhoris, Mohamed F
2016-07-01
In this paper is proposed a new balancing three-level three dimensional space vector modulation (B3L-3DSVM) strategy which uses a redundant voltage vectors to realize precise control and high-performance for a three phase three-level four-leg neutral point clamped (NPC) inverter based Shunt Active Power Filter (SAPF) for eliminate the source currents harmonics, reduce the magnitude of neutral wire current (eliminate the zero-sequence current produced by single-phase nonlinear loads), and to compensate the reactive power in the three-phase four-wire electrical networks. This strategy is proposed in order to gate switching pulses generation, dc bus voltage capacitors balancing (conserve equal voltage of the two dc bus capacitors), and to switching frequency reduced and fixed of inverter switches in same times. A Nonlinear Back Stepping Controllers (NBSC) are used for regulated the dc bus voltage capacitors and the SAPF injected currents to robustness, stabilizing the system and to improve the response and to eliminate the overshoot and undershoot of traditional PI (Proportional-Integral). Conventional three-level three dimensional space vector modulation (C3L-3DSVM) and B3L-3DSVM are calculated and compared in terms of error between the two dc bus voltage capacitors, SAPF output voltages and THDv, THDi of source currents, magnitude of source neutral wire current, and the reactive power compensation under unbalanced single phase nonlinear loads. The success, robustness, and the effectiveness of the proposed control strategies are demonstrated through simulation using Sim Power Systems and S-Function of MATLAB/SIMULINK.
Chebabhi, Ali; Fellah, Mohammed Karim; Kessal, Abdelhalim; Benkhoris, Mohamed F
2016-07-01
In this paper is proposed a new balancing three-level three dimensional space vector modulation (B3L-3DSVM) strategy which uses a redundant voltage vectors to realize precise control and high-performance for a three phase three-level four-leg neutral point clamped (NPC) inverter based Shunt Active Power Filter (SAPF) for eliminate the source currents harmonics, reduce the magnitude of neutral wire current (eliminate the zero-sequence current produced by single-phase nonlinear loads), and to compensate the reactive power in the three-phase four-wire electrical networks. This strategy is proposed in order to gate switching pulses generation, dc bus voltage capacitors balancing (conserve equal voltage of the two dc bus capacitors), and to switching frequency reduced and fixed of inverter switches in same times. A Nonlinear Back Stepping Controllers (NBSC) are used for regulated the dc bus voltage capacitors and the SAPF injected currents to robustness, stabilizing the system and to improve the response and to eliminate the overshoot and undershoot of traditional PI (Proportional-Integral). Conventional three-level three dimensional space vector modulation (C3L-3DSVM) and B3L-3DSVM are calculated and compared in terms of error between the two dc bus voltage capacitors, SAPF output voltages and THDv, THDi of source currents, magnitude of source neutral wire current, and the reactive power compensation under unbalanced single phase nonlinear loads. The success, robustness, and the effectiveness of the proposed control strategies are demonstrated through simulation using Sim Power Systems and S-Function of MATLAB/SIMULINK. PMID:27018144
DEFF Research Database (Denmark)
Ma, Ke; Blaabjerg, Frede
2012-01-01
investigates the loss and thermal performances of a 10 MW 3L-NPC wind power inverter undergoing Low Voltage Ride Through (LVRT) operation. A series of new space vector modulation methods are then proposed to relocate the thermal loading among the power switching devices. It is concluded that, with the proposed......The three-level neutral-point-clamped (3L-NPC) converter is a promising multilevel topology in the application of mega-watts wind power generation system. However, the growing requirements by grid codes may impose high stress and even give reliability problem to this converter topology. This paper...... modulation methods, the thermal distribution in the 3L-NPC wind power inverter undergoing LVRT becomes more equal, and the junction temperature of the most stressed devices can be also relieved. Also the control ability of DC-bus neutral point potential, which is one of the crucial considerations for the 3L...
Institute of Scientific and Technical Information of China (English)
殷立; 王顺强
2012-01-01
The inner intrinsic safety of BUCK-BOOST convert is analyzed by minimum ignition curve. The worst-case energy of BUCK-BOOST is calculated. Comparing with the minimum ignition curve, the intrinsic safety of BUCK-BOOST convert is implemented. Through calculation, the maximum load capacitor and inductance are obtained.%从最小点燃曲线角度分析BUCK-BOOST变换器内部本质安全性能,推算出BUCK-BOOST最恶劣情况下的能量,与火花点燃曲线相比较,得到本安输出的BUCK-BOOST变换器,并通过计算得出最大负载电容及负载电感。
DEFF Research Database (Denmark)
Loh, Poh Chiang; Duan, Na; Liang, Chao;
2007-01-01
reduced component count topology. Proposing alternative configurations with a reduced active semiconductor count, this paper discusses the systematic design of a number of Z-source B4 inverters, whose buck-boost capability is attained passively by inserting LC elements and clamping diodes. Visually, the...... circuitries, hence enhancing reliability. To validate the inverter performance and practicality, experimental testing is performed with a set of representative results presented in the paper for viewing. Advantages and disadvantages of the proposed inverters, as compared to existing circuitries, are also...
Energy Technology Data Exchange (ETDEWEB)
Widyan, M.S.
2010-07-01
Photovoltaic (PV) cells for powering direct current (DC) motors are designed to provide maximum output power at the rated conditions of the motors. This paper presented the dynamic and steady-state characteristics of DC shunt, series and permanent-magnet motors fed by PV cells via a DC-DC buck-boost (step up-step down) switch mode converter. It considered the nonlinearities of the output characteristics of the PV cells and that of the magnetization curve of the machines. In order to address the problem of voltage regulation of the PV cells and the variation in solar illumination, the duty cycle controls the output voltage of the DC-DC converter to maintain a fixed voltage across the terminals of the motors at any realistic loading conditions. In this study, the DC-DC buck-boost switch mode converter achieved a fixed voltage across the terminals of the motors and therefore good speed regulation under a wide range of loading conditions and solar intensities. The entire study was carried out using the Matrix Laboratory Program MATLAB{sup TM} software.
Directory of Open Access Journals (Sweden)
Bharati Raja
2012-12-01
Full Text Available This work presents the comparative study of the different PWM techniques to reduce the common-mode voltage (CMV at the output of neutral point diode clamped inverter for variable speed drives. Here the comparative study is done by the phase opposition disposed (POD, sinusoidal pulse width modulation (SPWM, phase disposition (PD, phase shift (PS space vector modulation (SVM techniques are proposed. A good trade-off between the quality of the output voltage and the partial magnitude of the CMV is achieved in this work. The scheme is proposed for three-level inverter. This work realizes the implementation of Three-level diode clamped MLI for three-phase (Y-Δ induction motor with the implementation of a space vector modulation technique without any additional control algorithm to reduce CMV within the range + Vdc/6. The Simulation with a 1HP induction motor drive system is setup in Matlab-2011b and the same results validated effectively by hardware – FPGA-SPARTEN III processor and its shows that the CM voltage is effectively reduced and the maximum output voltage is not affected.
Directory of Open Access Journals (Sweden)
Faqiang Wang
2011-01-01
Full Text Available The influence of switching frequency on the low-frequency oscillation in the voltage-controlled buck-boost converter is studied in this paper. Firstly, the mathematical model of this system is derived. And then, a glimpse at the influence of switching frequency on the low-frequency oscillation in this system by MATLAB/Simulink is given. The improved averaged model of the system is established, and the corresponding theoretical analysis is presented. It is found that the switching frequency has an important influence on the low-frequency oscillation in the system, that is, the low-frequency oscillation is easy to occur when the switching frequency is low. Finally, the effectiveness of the improved averaged model and the theoretical analysis are confirmed by circuit experiment.
Institute of Scientific and Technical Information of China (English)
刘文江; 张晓军; 王旭光
2006-01-01
提出和设计了一种新型BUCK-BOOST AC-AC变换电路,详细阐述了其结构和工作原理.该电路采用ARM嵌入式处理器和先进的控制策略,实现了全数字控制.实验结果表明,该电路具有很好的调压效果.
Institute of Scientific and Technical Information of China (English)
张伦健; 卢春艳; 陈利萍
2013-01-01
研究了一种具有升降压能力的中点箝位型(NPC)三电平Z源逆变器(ZSI),给出三电平ZSI拓扑结构,并分析其工作原理.基于传统三电平逆变器的空间矢量调制原理,设计了一种不需要死区延时的三电平ZSI空间矢量调制法,通过对两个阻抗网络进行选择性直通控制,使三电平ZSI对直流输入电压进行升压的同时,不会产生额外的器件换流.基于Matlab/Simulink搭建仿真模型对所设计的空间矢量调制法进行仿真分析,仿真结果表明所设计的调制法具有有效性.%A neutral-point-clamped (NPC) three level Z source inverter with both voltage-buck and voltage-boost capabilities was studied in this paper.The topologic of three level Z source inverter was provided,and its basic principle was analyzed.Based on space vector modulation algorithm of conventional three level inverter,an appropriate pulse width modulation (PWM) algorithm with no requirement for deadtime delay was designed for three level Z source inverter by short circuiting two impendence network selectively,it made the Z source inverter have the minimal device commutations per switching cycle when ZSI boosted the voltage.In order to verify the designed SVPWM algorithm,the simulation model of three level Z source inverter was built.The simulation results demonstrate that the designed SVPWM algorithm was valid.
George, Libin; Gargiulo, Gaetano Dario; Lehmann, Torsten; Hamilton, Tara Julia
2016-06-01
This paper presents the design of a reconfigurable buck-boost switched-capacitor DC-DC converter suitable for use in a wide range of biomedical implants. The proposed converter has an extremely small footprint and uses a novel control method that allows coarse and fine control of the output voltage. The converter uses adaptive gain control, discrete frequency scaling and pulse-skipping schemes to regulate the power delivered to a range of output voltages and loads. Adaptive gain control is used to implement variable switching gain ratios from a reconfigurable power stage and thereby make coarse steps in output voltage. A discrete frequency scaling controller makes discrete changes in switching frequency to vary the power delivered to the load and perform fine tuning when the output voltage is within 10% of the target output voltage. The control architecture is predominately digital and it has been implemented as part of a fully-integrated switched-capacitor converter design using a standard bulk CMOS 0.18 μm process. Measured results show that the converter has an output voltage range of 1.0 to 2.2 V, can deliver up to 7.5 mW of load power and efficiency up to 75% using an active area of only 0.04 mm (2), which is significantly smaller than that of other designs. This low-area, low-complexity reconfigurable power converter can support low-power circuits in biomedical implant applications. PMID:26600247
George, Libin; Gargiulo, Gaetano Dario; Lehmann, Torsten; Hamilton, Tara Julia
2016-06-01
This paper presents the design of a reconfigurable buck-boost switched-capacitor DC-DC converter suitable for use in a wide range of biomedical implants. The proposed converter has an extremely small footprint and uses a novel control method that allows coarse and fine control of the output voltage. The converter uses adaptive gain control, discrete frequency scaling and pulse-skipping schemes to regulate the power delivered to a range of output voltages and loads. Adaptive gain control is used to implement variable switching gain ratios from a reconfigurable power stage and thereby make coarse steps in output voltage. A discrete frequency scaling controller makes discrete changes in switching frequency to vary the power delivered to the load and perform fine tuning when the output voltage is within 10% of the target output voltage. The control architecture is predominately digital and it has been implemented as part of a fully-integrated switched-capacitor converter design using a standard bulk CMOS 0.18 μm process. Measured results show that the converter has an output voltage range of 1.0 to 2.2 V, can deliver up to 7.5 mW of load power and efficiency up to 75% using an active area of only 0.04 mm (2), which is significantly smaller than that of other designs. This low-area, low-complexity reconfigurable power converter can support low-power circuits in biomedical implant applications.
Nine Level Inverter with Boost Converter from Renewable Energy Source
Directory of Open Access Journals (Sweden)
Maruthu Pandiyan.R
2015-01-01
Full Text Available A new single phase nine level multilevel inverter is proposed. The input to the proposed nine level multilevel inverter is obtained from solar panel . The solar energy obtained from the solar panel is not constant and it varies with times. In order to maintain the constant voltage obtained from the solar panel the boost converter is used to maintain the constant output voltage using MPPT ( Perturb and observe algorithm algorithm. Then the buck boost converter output voltage is stored in the battery bank. Finally the battery energy is connected to the 9 level inverter circuits. The harmonics in the inverter is eliminated by using the fuzzy logic controller. The gate pulse for the multilevel inverter is given by the fuzzy logic controller which in turn reduces the harmonics in the inverter. Then the inverter output is connected to the grid are some application.
Magnetically Coupled Impedance-Source Inverters
DEFF Research Database (Denmark)
Loh, Poh Chiang; Blaabjerg, Frede
2013-01-01
input-to-output gain and the presence of an impedance network. The former means a high dc-link voltage, which can stress the semiconductor switches unnecessarily. The latter leads to increases in cost and size, which similarly are undesirable. To lessen these concerns, an interesting approach is to use......Z-source inverters are a new class of inverters proposed with output voltage or current buck-boost ability. Despite their general attractiveness, there are some present limitations faced by existing Z-source inverters, most of which are linked to their requirement for low modulation ratio at high...... magnetically coupled transformers or inductors to raise the gain and modulation ratio simultaneously, while reducing the number of passive components needed. A study of the approach is now presented to show how various existing magnetically coupled inverters can be derived by applying a generic methodology...
Magnetically coupled impedance-source inverters
DEFF Research Database (Denmark)
Loh, Poh Chiang; Blaabjerg, Frede
2012-01-01
input-to-output gain, and the presence of an impedance network. The former means a high dc-link voltage, which can stress the semiconductor switches unnecessarily. The latter leads to increases in cost and size, which similarly are undesirable. To lessen these concerns, an interesting approach is to use......Z-source inverters are a new class of inverters proposed with output voltage or current buck-boost ability. Despite their general attractiveness, there are some present limitations faced by existing Z-source inverters. Most of which are linked to their requirement for low modulation ratio at high...... magnetically coupled transformers or inductors to raise the gain and modulation ratio simultaneously, while reducing the number of passive components needed. A study of the approach is now presented to show how various existing magnetically coupled inverters can be derived by applying a generic methodology...
Energy Technology Data Exchange (ETDEWEB)
Erdman, W.; Keller, J.; Grider, D.; VanBrunt, E.
2014-11-01
A high-efficiency, 2.3-MW, medium-voltage, three-level inverter utilizing 4.5-kV Si/SiC (silicon carbide) hybrid modules for wind energy applications is discussed. The inverter addresses recent trends in siting the inverter within the base of multimegawatt turbine towers. A simplified split, three-layer laminated bus structure that maintains low parasitic inductances is introduced along with a low-voltage, high-current test method for determining these inductances. Feed-thru bushings, edge fill methods, and other design features of the laminated bus structure provide voltage isolation that is consistent with the 10.4-kV module isolation levels. Inverter efficiency improvement is a result of the (essential) elimination of the reverse recovery charge present in 4.5-kV Si PIN diodes, which can produce a significant reduction in diode turn-off losses as well as insulated-gate bipolar transistor (IGBT) turn-on losses. The hybrid modules are supplied in industry-standard 140 mm x 130 mm and 190 mm x 130 mm packages to demonstrate direct module substitution into existing inverter designs. A focus on laminated bus/capacitor-bank/module subassembly level switching performance is presented.
NPC型三电平逆变器供电的永磁同步电机矢量控制系统%PMSM vector control system by NPC three-level inverter-fed
Institute of Scientific and Technical Information of China (English)
谢剑云; 徐华勒
2014-01-01
Because three -level neutral point clamped ( NPC ) inverter has less distorted output , good control performance and other advantages , a new vector control method for the permanent magnet synchronous motor ( PMSM) based on a three-level NPC inverter is presented .Firstly, the three-level NPC inverter space voltage vector pulse width modulation ( SVPWM ) technique is analyzed in detail . Then, this NPC inverter is applied in PMSM vector control .Finally, a simulation experiment of the pro-posed control algorithm is carried out .The simulation results show the proposed method can effectively suppress the torque ripple and improve driving performance for the PMSM driver system .%在分析永磁同步电机矢量控制理论的基础上，结合三电平中点钳位（ NPC）逆变器输出谐波含量低、控制性能好等优点，提出了一种基于NPC型三电平逆变器的永磁同步电机（ PMSM ）矢量控制方法。深入分析了三电平逆变器空间电压矢量脉宽调制（ SVPWM ）技术，并利用Matlab/Simulink进行了基于三电平逆变器SVPWM算法的PMSM矢量控制仿真实验，结果表明三电平逆变器SVPWM和PMSM矢量控制的有机结合，有效地抑制了转矩脉动，提高了驱动性能。
Research on Three-phase and Three-level PV's Inverter Based on SVPWM%基于SVPWM的三相三电平光伏并网逆变器的研究
Institute of Scientific and Technical Information of China (English)
张雪; 曹勇; 胡艳美; 邢峰华
2015-01-01
For two-stage grid-connected inverter of photovoltaic system, the controlling method of a three-phase and three-level inverter was introduced based on voltage space vector, so it can achieve a lower switching frequency, weaken the waveform distortion of line current in the AC side, and improve power factor in the AC side. The structure of a three-phase and three-level photovoltaic grid inverter was designed and the system incremental method was used to achieve maximum power tracking; The grid inverter control mode selects SVPWM. In addition, this paper sets up the simulation model through Matlab/Simulink to verify the feasibility system and improve the power quality of grid inverter.%针对两级式光伏发电系统的并网逆变器，提出基于电压空间矢量作为三相三电平逆变器的控制方式，实现了降低开关频率，减弱了交流侧线电流的波形畸变，提高交流侧的功率因数。设计了三相三电平光伏并网逆变器系统的结构，采用导纳增量法实现最大功率跟踪，并网逆变器的控制方式选用 SVPWM ，并通过Matlab/Simulink搭建仿真模型，验证了系统可行性，改善了并网逆变器的电能质量。
DEFF Research Database (Denmark)
Blaabjerg, Frede; Vilathgamuwa, D. M.; Loh, Poh Chiang;
2009-01-01
Distributed generation (DG) systems are usually connected to the grid using power electronic converters. Power delivered from such DG sources depends on factors like energy availability and load demand. The converters used in power conversion do not operate with their full capacity all the time......-stage buck-boost inverter, recently proposed Z-source inverter (ZSI) is a good candidate for future DG systems. This paper presents a controller design for a ZSI-based DG system to improve power quality of distribution systems. The proposed control method is tested with simulation results obtained using...
Institute of Scientific and Technical Information of China (English)
张佩炯
2011-01-01
空间矢量脉宽调制在多电平逆变器的控制中应用广泛,但是随着电平数增加,控制算法渐趋复杂化。提出了三电平空间矢量脉宽调制控制方法,将三电平电压矢量区变换为由两电平空间矢量区构成,从而通过使用两电平空间矢量脉宽调制方法简化了控制算法。该方法理论上可应用于更高电平逆变器的控制中,仿真验证了方法的可行性。%Space vector pulse width modulation is widely applied in control of multi-level inverters, but following increasing of level number, the control algorithm becomes more and more complicated. Three-level space vector pulse width modulation control method was raised to transfer three-level voltage vector zone to two-level space vector zones, so as to simplify the control algorithm with two-level space vector pulse modulation method. The method on the theory can be used to control much higher level inverters and simulation has verified feasibility of the method.
基于不同调制方式的三电平逆变器仿真研究%Research and simulation of three-level inverter based on different modulations
Institute of Scientific and Technical Information of China (English)
牛海伟; 任永峰; 刘峰; 关勇; 丛雨
2013-01-01
首先讨论了三电平二极管中点箝位型PWM逆变器电路拓扑,其次分析了空间电压矢量脉宽调制(SVPWM)的基本原理,并在Matlab/simulink中对三电平逆变器进行了仿真,然后分析了载波相移调制(CPS-SPWM)技术的基本原理,并利用这种调制方式在PSIM仿真软件中对三电平逆变器进行了仿真,仿真结果证实了SVPWM算法和CPS-SPWM实现方法是正确可行的.%The circuit topology of the three-phase,three-level,and diode neutral-point-clamped PWM inverter was discussed,and the basic principle of the SVPWM was analyzed.The vector space was divided into six large areas,and each large one was divided into six small areas.The simulation model of the control system for the three-phase three-level PWM inverter was established in the Matlab simulation environment.The simulation results verify that the proposed vector PWM algorithm and realizing method are valid and feasible.
A Non-isolated Three-level Dual Buck Photovoltaic Grid-connected Inverter%一种不隔离三电平双Buck光伏并网逆变器
Institute of Scientific and Technical Information of China (English)
嵇保健; 洪峰; 赵剑锋
2012-01-01
To enhance conversion efficiency,the study of photovoltaic grid-connected inverter without transformers is an important trend.In order to avoid leakage currents of grid-connected inverters without transformer,a novel three-level dual Buck grid-connected inverter was proposed,which obtained by simplifying the structure of three-level dual Buck inverters.The voltage of the stray capacitor to ground,which was clamped by the huge input capacitors,was equal to the half value of the bus voltage,so the leakage current was eliminated.The current of this topology pass through fewer elements than that of traditional topology and would not pass through body diodes,so that it could achieve higher efficiency.Meanwhile,a multi-loop control method including voltage-balancing control was proposed and analyzed.Both simulation and experimental results verify that the structure and the control method of this grid-connected inverter is correct and feasible.%为提高变换效率,无变压器式光伏并网逆变器是近年来的研究热点。针对无变压器拓扑的漏电流问题,提出一种三电平双Buck光伏并网逆变器,是在独立型双Buck三电平逆变器基础上,简化其电路结构得到。对地寄生电容电压被输入电容钳位在母线电压的一半,消除了漏电流。该拓扑续流回路经过的器件较传统拓扑数量少,且不经过性能较差的体二极管,有利于获得更高效率。还提出和分析包括均压控制在内的多环控制策略。仿真和实验验证了该结构及控制方案的正确性和可行性。
Institute of Scientific and Technical Information of China (English)
俞鹏; 王明渝; 王磊
2010-01-01
研究了一种新型的三相单级Buck-Boost PFC变换器,用一个PWM信号同时控制4个开关管的通断状态,实现升/降压调压;基于交流侧的LC滤波实现了功率因数校正,并解决了传统的Buck-Boost变换器体积过大和输出电压反向的问题.介绍了变换器的工作原理并分析了稳态时的工作状况、输入电流谐波状况;设计了电压闭环控制系统;利用MATLAB/Simulink建立仿真模型,仿真结果验证了变换器的性能.
Novel, Four-Switch, Z-Source Three-Phase Inverter
DEFF Research Database (Denmark)
Antal, Robert; Muntean, Nicolae; Boldea, Ion;
2010-01-01
This paper presents a new z-source three phase inverter topology. The proposed topology combines the advantages of a traditional four-switch three-phase inverter with the advantages of the z impedance network (one front-end diode, two inductors and two X connected capacitors). This new topology......, besides the self-boost property, has low switch count and it can operate as a buck-boost inverter. In contrast to standard four-switch three-phase inverter which operates at half dc input voltage the proposed four-switch z-source inverter, by self boosting, brings the output voltage at same (or higher......) value as in six switch standard three-phase inverter. The article presents the derivation of the equations describing the operation of the converter based on space vector analysis, validation through digital simulations in PSIM and preliminary experimental results on a laboratory setup with a dsPIC30F...
Institute of Scientific and Technical Information of China (English)
周熙炜; 梅芳; 陈金平; 林海
2016-01-01
深入分析基本空间矢量SV与特定谐波消去SHEPWM之间的内在联系，提出三电平NPC逆变器的一种基于空间分区矢量提取的SHEPWM调制策略,推导出空间电压矢量PWM的三相等效调制波规则采样的开关角矩阵，得出基本空间矢量SV的选用与规则采样的运算关系以及SHEPWM的脉冲状态由基本SV组成的矢量序列特殊解。在此基础上，在三电平NPC逆变器的矢量空间六边形所分区的两电平六边形中，研究SHEPWM脉冲序列的空间电压矢量组成的扇区分布，并提取相应的基本SV，求解作用时间。 SHEPWM的脉冲状态由空间分区提取的基本SV矢量序列运算合成而实现，避开了其开关角非线性超越方程组的求解，并具有同样的消谐效果且便于实现。%According to the studies of internal relation for the basic space vector(SV) and the selective harmonic elimination PWM (SHEPWM), this paper puts forward a kind of SHEPWM implementation strategy based on the space partition vector SV extraction to the three-level NPC inverter, deduces the space voltage vector switch angle matrix of the three-phase equivalent modulation wave regulation sampling and the operation relationship. So, on the basis of the switch angle trajectory characteristics of SHEPWM and its realization by regulation sampling, the SHEPWM waveform pulse state can be gained by the vectors sequence special solution which composed of basic SV vector. To the three-level inverter, on the Two level small hexagon which be partitioned from space vector hexagon, the work sector allocation of SHEPWM pulse state be researched, and the corresponding basic SV vector and its action time also be achieved by the experiment and FFT analysis. This method avoid the solution of SHEPWM switch angle nonlinear transcendental equations, and it has the same effect of harmonic elimination and to facilitate online implementation.
Institute of Scientific and Technical Information of China (English)
宋文祥; 张旭
2012-01-01
在电机控制过程中,死区和管压降的存在导致逆变器输出波形畸变.为了消除电压和电流的畸变,死区和管压降补偿是必要的.本文给出了一种简洁高效的三电平电压型逆变器死区补偿方法,用以改善电机的输出波形,详细分析了死区产生机理,利用电流矢量对死区进行准确补偿.根据PWM状态和电流矢量的位置分析功率器件压降的变化,结合电流方向进行补偿.最后基于F2812DSP芯片的三电平逆变器实验平台对该方法进行了开环和闭环实验研究,验证了理论分析的正确性和实际可行性.%In order to prevent the output waveforms distortion due to dead-time and forward voltage, we must add the dead-time and forward voltage compensation in the process of motor control. This paper introduced a simple and efficient dead-time compensation method for three-level inverter to improve output waveforms. The cause of dead-time was analysed in detail, and dead-time can be compensated accurately using current vector. We analyse the changes in forward voltage of power devices based on PWM state and the position of current vector, and then compensate according to the current direction. Finally open and closed loop experiments are done to prove the proposed strategy through experiment on a three-level model inverter developed with F2812DSP. We can prove that the analysis is correct and the method can be used in practice.
Directory of Open Access Journals (Sweden)
S. Suresh Kumar,
2014-01-01
Full Text Available A modified pulse width modulation technique for Z-source inverter based BLDC motor is proposed and analyzed in this project.The Z-source inverter can be used as Buck/Boost converter with lower cost and high efficiency. BLDC motors are used in electric vehicles where portability and efficiency are required. This drive system provides advantages of both BLDC motors and Z-source inverter, and can be used in fuel cell system and other adjustable speed drive application. In this project principle of modified pulse width modulation technique is implemented and simulated. The model of a three phase Z-source inverter has been discussed based on modified pulse with modulation technique. The simulation of Z-source inverter based BLDC motor is done using the MATLAB/SIMULINK.
Power decoupling with autonomous reference generation for single-phase differential inverters
DEFF Research Database (Denmark)
Yao, Wenli; Zhang, Xiaobin; Wang, Xiongfei;
2015-01-01
The second-harmonic power ripple in single-phase inverter may introduce the issue of low reliability and low power density. In order to replace the bulky dc-link capacitor, an alternative approach is to use active power decoupling so that the ripple power can be diverted into other energy storages....... However, the performance of existing active power decoupling methods depends heavily on certain control references, which unfortunately are parameter dependent. In this paper an autonomous reference generation technique is proposed for single phase differential inverter without relying on the system...... parameters. A unified average switching model is firstly derived for Buck, Buck-Boost and Boost differential inverter, which is apparently have nonlinear characteristics. Then, dual-loop cascading control and a feedback linearization method is employed to design the inner- and outer loop controllers, which...
Institute of Scientific and Technical Information of China (English)
姚川; 阮新波; 曹伟杰; 陈沛琳
2013-01-01
The two-switch Buck-Boost (TSBB) converter is suitable for wide input voltage applications, and a two-mode control scheme with two modulation signals and one carrier can be adopted to achieve high efficiency and automatic modes-switching over the entire input voltage range. The corresponding operating modes are the Buck mode with high input voltages and the Boost mode with low input voltage. In order to reduce the influence of the input voltage disturbance on the output voltage, input voltage feed-forward (IVFF) functions based on the small-signal models of different operating modes were derived, and the effect of the variable circuit parameters on the IVFF functions was analyzed, then a two-mode control scheme with IVFF compensation was proposed. With this proposed control scheme for the TSBB converter, automatic selections of operating modes and the corresponding IVFF functions can be achieved simultaneously. Besides, nearly smooth switching between Buck and Boost modes is guaranteed. Then, high efficiency and improved input transient response over the entire input voltage range are both achieved. For exhibiting the advantages of the proposed control scheme clearly, comparisons between the two-mode control with and without IVFF compensation had been presented in this paper. Finally, a suitable power prototype was fabricated to validate the effectiveness of the control scheme.% 双管Buck-Boost变换器适用于宽输入电压范围场合。采用双调制–单载波的两模式控制策略可实现其整个输入电压范围内的高效率和工作模式的自动平滑切换，其工作模式即为高输入电压区间的 Buck 模式和低输入电压区间的Boost模式。为抑制输入电压扰动对输出电压的影响，通过建立双管Buck-Boost变换器不同工作模式下的小信号模型，推导相应的输入电压前馈函数，并分析电路参数变化对前馈函数的影响，进而提出一种带输入电压前馈的两模式控制
Push-Pull Converter Fed Three-Phase Inverter for Residential and Motor Load
Directory of Open Access Journals (Sweden)
Samuel Rajesh Babu
2015-06-01
Full Text Available The proposed paper is an new approach for power conditioning of a PV (photo-voltaic cell array. The main objective is to investigate an approach to provide and improve the delivered electric energy by means of power conditioning structures with the use of alternative renewable resources (ARRs for remote rural residential or industrial non-linear loads. This approach employs a series-combined connected boost and buck boost DC-DC converter for power conditioning of the dc voltage provided by a photo-voltaic array. The input voltage to the combined converters is 100 V provided from two series connected PV cells, which is converted and increased to 200 V at the dc output voltage. Series-combined connected boost and buck-boost DC-DC converters operate alternatively. This helps to reduce the input ripple current and provide the required 400 Vdc on a sinusoidal PWM three-phase inverter. Analysis of the two series-combined DC-DC converters is presented along with simulation results. Simulations of the series-combined DC-DC converters are presented with an output DC voltage of 200 V and a maximum output load of Po = 600 W.
Directory of Open Access Journals (Sweden)
A. Santhi Mary Antony
2015-06-01
Full Text Available Current fed Quasi Z-Source Inverters (qZSI have the advantages of voltage buck-boost capability, improved reliability, reduced passive component ratings, continuous input current, a common dc rail between source and inverter and unique regeneration capability. This current-fed qZSIs are bidirectional with an additional diode, unlike the voltage-fed ZSI that needs a switch to achieve bidirectional power flow. Since current fed quasi Z Source Inverter has many advantages it can be employed for motor drive applications such as Brushless DC motor (BLDC drive. Therefore this study proposes the use of qZSI for BLDC motor. The simulation results for the same are presented in this study.
DEFF Research Database (Denmark)
Gajanayake, C.J.; Vilathgamuwa, D.M.; Loh, P.C.;
2007-01-01
, the utility has an obligation to deliver a quality supply to consumers. Interestingly, with the increase in energy demand and penetration of renewable sources, generation units popularly known as Distributed Generators (DGs) are increasingly connected at the distribution level. Most of these sources...... functions of the power distribution like harmonics and unbalance mitigation etc. Moreover, some of these DG sources have large operating ranges demanding special converters with wide operating range. Being a single stage buck-boost inverter, recently proposed Z-source inverter is a good candidate for future...... DG systems. Considering these factors, this paper presents the controller design for a Z-source inverter based DG system to improve the power quality of distribution systems. To improve the reference tracking and to eliminate harmonics, a p+resonance and repetitive controller designed using a simple...
Institute of Scientific and Technical Information of China (English)
陈国呈; 宋文祥; 武慧; 孙承波
2006-01-01
This paper proposes a novel SVPWM ( space vector pulse width modulation) strategy for the three-level neutral-point-clamped voltage source inverter, based on the particular disposition of all the redundant voltage vectors. The new modulation approach shows superior performance for harmonic voltage and balancing control of neutral-point potential compared to the popular eight-stage centered SVPWM. It realizes suppression of inverter neutral-point potential variation by accurately modifying redundant factor of small vectorspairs, only requiring information of DC-link capacitor voltages and three-phase load currents. This is convenient to apply and is compatible of digital computer realization. Feasibility of the proposed control approach is verified by simulation and experimental results.
A Robust Chattering-Avoiding Sliding Mode Control for Buck-Boost Converter%一种鲁棒无抖颤滑模控制的Buck-Boost变换器
Institute of Scientific and Technical Information of China (English)
皇甫宜耿; 吴宇; 马瑞卿
2014-01-01
In the process of power generation by new energy sources, such as wind, light and hydrogen, the ran-domness of energy input and power output often appear;this puts forward higher requirements for the robust design of power converters. The power converter based on traditional sliding mode, due to its discrete control law, makes chattering phenomenon inevitable. In order to suppress the above problem, this paper presents a novel chattering-avoiding converter based on the super-twisting sliding modes. The core idea is to transfer the discrete control law to high order sliding manifold, essentially eliminating the impact of chattering effect. To remove the intermittent dis-turbance in the new energy power generation, this paper compares the effect of the converter controlled by super-twisting sliding mode controller with the classic PI controller in a typical Buck-Boost power converter as an example. The simulation results and their analysis show preliminarily that: (1) under the condition of large disturbances in input and output, the converter controlled by super-twisting sliding mode has stronger robustness;(2) in response tracking, the converter has a faster convergence;the frequency response can reach more than 20 Hz, far superior to the classic PI control.%利用风、光、氢等新能源发电过程中，经常遇到能量输入和功率输出的随机性，这对电源变换器鲁棒性设计提出了更高要求。针对传统滑模控制变换器由于自身控制律的离散型存在不可避免的抖颤问题，基于一种Super-Twisting控制算法设计无抖颤滑模变换器，其核心思想是将离散控制律转移至更高阶的滑模面，从本质上消除抖颤的影响。以电源变换器Buck-Boost为例，针对新能源发电中存在的间歇性扰动问题，与典型PI控制效果进行对比试验。仿真结果表明：1）动态滑模控制变换器在输入、输出大扰动下具有很强的鲁棒性；2）在频响跟踪方面具
Directory of Open Access Journals (Sweden)
Meenakshi T.
2016-09-01
Full Text Available This paper presents the modeling and simulation of a novel topology of quasi Z-Multilevel Inverter with stepped DC input. The proposed inverter incorporates a simple switching technique with reduced component count and is aimed at producing boosted multilevel output AC voltage. The inverter consists of two stages and the buck /boost operation is obtained by varying the shoot through period of the pulses obtained by maximum constant boost control with third harmonic injection. With all the advantages of the quasi Z-network, the proposed inverter eliminates the fly back diodes and capacitors present in a conventional Z-Multilevel Inverter. Further the stress on the devices is less which leads to reduction in component value and hence the cost. The novel stepped DC coupled Single Phase quasi Z-Multilevel Inverter is modeled and simulated in the MATLAB - SIMULINK environment and its performance is analyzed for varying input and switching conditions. The voltage and current waveforms across each stage of the inverter is analyzed and the results are presented for different levels of input.
Institute of Scientific and Technical Information of China (English)
毛惠丰; 孔德鹏; 陈增禄; 杨旭; 王兆安
2015-01-01
提出了一种单相 H 桥电压型逆变器三电平滞环电流跟踪控制方法。该控制方法具有载波移相PWM调制效果以及无死区效应的特点。在稳态条件下，误差电流被严格限制在内环中。当指令电流发生突变并且达到外环的上或下阈值时，逆变器输出最高或最低电平以使误差电流以最快速度趋近于0。与传统的三电平滞环电流控制方法相比，该控制方法能进一步改善逆变器输出电流的波形。通过仿真和实验结果验证了该方法的有效性。%ABSTRACT:A new three-level hysteresis current controller for single-phase H-bridge voltage source inverters (VSI) is proposed here. The proposed hysteresis current controller has successfully combined the advantage of the symmetrical unipolar carrier-based PWM and no dead-time effects. Under steady-state conditions, the current error will be confined within the inner band. When the commanded current step changes so that the current error exceeds the outer hysteresis band, the extreme voltage level is selected to force the current error towards zero quickly. Compared with the conventional three-level hysteresis current controller, the proposed hysteresis current controlled single-phase H-bridge voltage source inverters can further improve the inverter output current waveform. Simulated and experimental results have been given to demonstrate the validity and features of the novel hysteresis current controller with the improved switching scheme.
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
A comparative study of hybrid system monitoring based on bond graph and Petri net modelling,A comparison of high-power converter topologies for the implementation of FACTS controllers,A Configuration and Control Method of DC Loop Type Distribution System - Including Distributed Generators,A Cost Effective Three-Level MOSFET Inverter for Low Power Drives,A discrete sliding mode control of a buck-boost inverter
Institute of Scientific and Technical Information of China (English)
张茂松; 王群京; 李国丽; 王秀芹
2016-01-01
The neutral-point potential balancing control is very important for the NPC three-level inverter, but existing literatures can’t accurately analysis the potential drift by physical model. This paper proposed an accurate mathematical model of the D-STATCOM based on NPC three-level inverter with unknown disturbances and parametric perturbation, and then a novel robust current control withL2-gain performance based on the combination with repetitive control and passivity-based control was realized. The analysis indicates that the basic reason for the neutral-point potential drift is the unbalanced distribution of active power caused by parametric perturbation. By injecting zero-sequence voltage, the neutral-point potential balancing control can be realized based on the active power exchange between the dc-link capacitors. The effectiveness and performance of this model and control strategy is verified by simulation and has been tested on a practical installation and operation of ±400kVar, 1.14kV equipment in coal mine power supply system.%中点电位的平衡控制是中点钳位式三电平拓扑安全可靠运行的关键，但现有文献均未能通过建立精确的数学模型对中点电位漂移的物理机理进行精确分析，控制参数整定困难。该文建立了考虑未知干扰和参数摄动影响的中点钳位式三电平 D-STATCOM 的精确数学模型，利用重复控制与无源性控制相结合的方法实现了基于鲁棒 L2性能准则的电流控制器设计，精确分析了参数摄动导致的有功能量分配不均是中点电位漂移的根本原因。通过零序分量注入，利用直流侧上下端电容器之间的有功能量交换实现了中点电位的平衡控制。通过仿真以及1.14 kV,±400 kVar煤矿供电系统的工程应用，验证了该文所建立模型的准确性以及所提控制算法的可行性和有效性。
Directory of Open Access Journals (Sweden)
E.Rajendran
2013-10-01
Full Text Available Wind energy is a leader area of application for variable-speed generators operating on the constant grid frequency. This paper depicts the power quality enhancement in wind power system using permanent magnet synchronous generator (PMSG and Quasi Z-source Inverter. The PMSG is connected to the power network by means of a quasi z-source inverter (qZSI. The PMSG are used by these technologies due to extraordinary characteristics such as a smaller amount weight and volume, superior performance, eradicate the gear box and no need of peripheral power in permanent magnet excitation. The PMSG overcome the induction generator and other generators, because of their splendid performances without take up the grid power. But Induction Generator always needs the grid connectionfor getting power to start. In this paper the quasi Z-source inverter is a present that is a novel topology conjugated from the traditional Z source Inverter. The qZSI inherits all the advantages of the ZSI, that is performs buck-boost, inversion and power control in wind energy conversion system (WECS Moreover, the proposed qZSI the matchless advantages of less component ratings and stable dc current from the source. All over boost control methods are built for the ZSI can be used by the qZSI .This Paper presents hysteresis current control technique for the quasi Z- source inverter.
Arctic research at three levels.
McNabb, Steven
2004-01-01
This paper is a posthumous publication of a Steven McNabb's presentation to the 1993 annual meeting of the American Anthropological Association. In it he described how the Social Transitions in the North research project involved explicit cross-cultural contact or participation at three levels: between scientists and public agencies; between scientists and study populations; and between research teams themselves. He explored a few of the entanglements and opportunities that arise in those interactions. Dr. McNabb urged northern researchers to avoid embracing rigid standards, for they will result in more entanglements and fewer opportunities. On the otherhand, if researchers are open-minded, they will be able to treat each dilemma as an opportunity that will make for better science.
Institute of Scientific and Technical Information of China (English)
王建渊; 雷国惠; 钟彦儒
2015-01-01
中点电位不平衡是二极管中点箝位( NPC)型三电平逆变器存在的固有问题，在学术及工程实践中受到了广泛关注。中点电位平衡控制方法可以分为两大类，硬件和软件方法，基于硬件的控制方法主要是依靠外部电路调整，一般通过Boost和Buck等电路对电容进行充放电来调节中点电位以达到平衡，因而增加了整个逆变器的成本。在深入分析引起中点电位不平衡因素的基础上介绍了一种提高中点电位鲁棒性的滞环控制+精确控制策略。该控制策略将滞环控制与精确控制方法相结合，设置一定的环宽作为两种算法的切换条件，超出设定环宽使用滞环控制，在环宽内使用精确控制方法。进行了仿真和实验验证，结果证明该方法解决了滞环控制粗略、存在控制盲区并且控制效果受功率因数影响大的问题，同时弥补了精确控制中当中点电压发生偏移以后不具备将中点电位拉回平衡点的能力。有效地抑制中点电位波动，提高中点电位控制的鲁棒性。%The unbalance of neutral-point potential is an inherent problem of three-level neutral point clamped ( NPC) inverter, it is paid wide range attention in academic research and engineering practice. This NPC method is divided into two types:hardware and software method. The hardware method mainly depends on external circuit to adjust, in with Boost and Buck circuit are used to control the capacitor charge and discharge and implement the balance of neutral point voltage. This method increases the cost of whole inverter. The factors were analyzed which cause the unbalance of neutral-point voltage, and one hysteresis and precise control strategy of improving the robustness of neutral-point voltage was introduced. This control strategy combines hysteresis control with precise control,and a certain band width is set as the two different control methods switching condition. If the
Institute of Scientific and Technical Information of China (English)
肖飞; 谢桢; 吕昊
2013-01-01
In order to improve the wave of voltage, a delay signal cancel(DSC) method has been used to distinguish and control the positive and negative sequence components. However, while reinforcing the voltage waveform, the method increases the imbalance of the current, which results in seriously neutral-point voltage oscillating, under the space vector pulse width modulation (SVPWM). Thus, impact of the negative sequence current to neutral-point voltage oscillation is calculated. The results show that the neutral-point control ability could be increased or decreased with the negative sequence component increasing, which is mostly depended on the power factor. When the modulate proportion is bigger than 0. 5, the neutral-point control ability can be descend to zero because of the inconsonance between the power factor and negative sequence gene. Moreover, the boundary of the ability to control the unbalance by controlling the redundant voltage small vectors is found. Therefore the neutral-point control SVPWM is built. Plus, a integrate control strategy for three-level neutral-point clamped (NPC) voltage source inverter with unbalanced load based on distinguishing and controlling the positive and negative sequence components by DSC is put forward. Simulation exhibit that by the presented method, the negative sequence voltage can be restrained, and the negative sequence current makes the neutral-point unbalanced, while the voltage fluctuation at the neutral-point is controlled by the integrate control strategy. It is proved that under the integrated control strategy, three-level NPC voltage source inverter( VSI) performs well with unbalance load.%为了改善不平衡负载条件下三电平中点钳位型(NPC)电压型逆变器的输出电压波形,采用了延迟信号撤销法(DSC)分离出正序和负序电压分量分别进行控制.但此方法在修正了电压波形的同时,会进一步增加输出电流的不对称性,导致在空间矢量脉宽调制算法(SVPWM)
Pérez Germán, Javer
2012-01-01
The PRIMES laboratory is a common platform shared by academics and industrialists around power electronics problems such as high temperature packaging or power electronics reliability. Because of its new development, new equipments have to be d In the field of power electronics, a multilevel inverter has to be designed. The main objective of this EPS project is to design the multilevel inverter. Some tasks could be : 1. Choice of the power converter architecture, 2. Simulati...
Three-level cervical disc herniation
Directory of Open Access Journals (Sweden)
St. Iencean Andrei
2015-09-01
Full Text Available Multilevel cervical degenerative disc disease is well known in the cervical spine pathology, with radicular syndromes or cervical myelopathy. One or two level cervical herniated disc is common in adult and multilevel cervical degenerative disc herniation is common in the elderly, with spinal stenosis, and have the same cause: the gradual degeneration of the disc. We report the case of a patient with two level cervical disc herniation (C4 – C5 and C5 – C6 treated by anterior cervical microdiscectomy both levels and fusion at C5 – C6; after five years the patient returned with left C7 radiculopathy and MRI provided the image of a left C6 – C7 disc herniation, he underwent an anterior microsurgical discectomy with rapid relief of symptoms. Three-level cervical herniated disc are rare in adults, and the anterior microdiscectomy with or without fusion solve this pathology.
Periodically driven three-level systems
Kenmoe, M. B.; Fai, L. C.
2016-09-01
We study the dynamics of a three-level system (ThLS) sinusoidally driven in both longitudinal and transverse directions and in the presence of a uniaxial anisotropy D entering the generic Hamiltonian through the zero-energy splitting term D (Sz)2 where Sz is the projection of the spin vector along the quantization direction. As a consequence of the addition of this term, the order of the symmetry group of the Hamiltonian is increased by a unit and we observe a sequence of cascaded SU(3) Landau-Zener-Stückelberg-Majorana (LZSM) interferometers. The study is carried out by analytically and numerically calculating the probabilities of nonadiabatic and adiabatic evolutions. For nonadiabatic evolutions, two main approximations based on the weak and strong driving limits are discussed by comparing the characteristic frequency of the longitudinal drive with the amplitudes of driven fields. For each of the cases discussed, our analytical results quite well reproduce the gross temporal profile of the exact numerical probabilities. This allows us to check the range of validity of analytical results and confirm our assumptions. For adiabatic evolutions, a general theory is constructed allowing for the description of adiabatic passages in arbitrary ThLSs in which direct transitions between states with extremal spin projections are forbidden. A compact formula for adiabatic evolutions is derived and numerically tested for some illustrative cases. Interference patterns demonstrating multiple LZSM transitions are reported. Applications of our results to the nitrogen vacancy center in diamond are discussed.
Directory of Open Access Journals (Sweden)
K.Mohan Krishna
2015-12-01
Full Text Available Multilevel inverter topology has developed recently as a very important alternative in the area of high power medium voltage energy control. In multilevel inverter, thethree basic types of topologies used are diode clamped inverter (neutral point clamped, capacitorclamped (flying capacitor and cascaded multi cell with separate dc sources. Multilevel inverters are used in medium voltage and high power applications with less harmonic contents. This paper proposes a software implementation of neutral point clamped (NPC three level voltage source inverter using space vector pulse width modulation (SVPWM techniques. The inverter feeds an electrical system which is controlled by field oriented control (FOC.The improvement of the control technique is achieved using intelligence techniques. The operation of the electrical system is verified in steady state and transient state responses. This software implementation is performed by using matlab/Simulink software. This paper gives comparison between SVPWM three phase three level with neutral point clamped and without neutral point clamped. Finally, the comparative study of different techniques was implemented.
INVERTER MULTI LEVEL TIPE JEMBATAN SATU FASA TIGA TINGKAT DENGAN MIKROKONTROLER AT89S51
Directory of Open Access Journals (Sweden)
A. Warsito A. Warsito
2012-02-01
Full Text Available Inverter is a power electronics circuit which is used to convert DC voltage and current to AC voltage andcurrent. In conventional inverter, most commonly used, only has three level voltage, those are +Vdc, -Vdc,and zero. Meanwhile both square inverters and SWPM inverter has big harmonic distortion. In SPWMinverter scheme, high frequency switching must be used to minimize total harmonic distortion (THD. Multilevel inverter is a type of inverter that has more than one level of voltage and current output.The major advantages of multi level inverters are a good voltage waveform, small harmonic dirtortion,switching component operated under low frequency, and it can supply a big power.This paper will discuse the construction of single phase three level multi level inverters, hardware testinginclude output waveform THD, and the comparisson of multilevel inverter with other conventional invertersscheme suc as PWM inverters modulation, and square waveform inverter. Atmel’s AT89S51 microcontrollerused to control switching scheme in this multi level inverter. By this power electronic circuit, it is expected alow cost and reliable multi level inverters prototipe.
Analytic Solutions of Three-Level Dressed-Atom Model
Institute of Scientific and Technical Information of China (English)
WANG Zheng-Ling; YIN Jian-Ping
2004-01-01
On the basis of the dressed-atom model, the general analytic expressions for the eigenenergies, eigenstates and their optical potentials of the A-configuration three-level atom system are derived and analysed. From the calculation of dipole matrix element of different dressed states, we obtain the spontaneous-emission rates in the dressed-atom picture. We find that our general expressions of optical potentials for the three-level dressed atom can be reduced to the same as ones in previous references under the approximation of a small saturation parameter. We also analyse the dependences of the optical potentials of a three-level 85Rb atom on the laser detuning and the dependences of spontaneous-emission rates on the radial position in the dark hollow beam, and discuss the probability (population) evolutions of dressed-atomic eigenstates in three levels in the hollow beam.
Hierarchical Three-level Ontology for Text Processing
Gladun, Victor; Velychko, Vitalii; Svyatogor, Leonid
2008-01-01
The principal feature of ontology, which is developed for a text processing, is wider knowledge representation of an external world due to introduction of three-level hierarchy. It allows to improve semantic interpretation of natural language texts.
Three-Level 48-Pulse STATCOM with Pulse Width Modulation
Singh, Bhim; Srinivas, Kadagala Venkata
2016-03-01
In this paper, a new control strategy of a three-level 48-pulse static synchronous compensator (STATCOM) is proposed with a constant dc link voltage and pulse width modulation at fundamental frequency switching. The proposed STATCOM is realized using eight units of three-level voltage source converters (VSCs) to form a three-level 48-pulse STATCOM. The conduction angle of each three-level VSC is modulated to control the ac converter output voltage, which controls the reactive power of the STATCOM. A fuzzy logic controller is used to control the STATCOM. The dynamic performance of the STATCOM is studied for the control of the reference reactive power, the reference terminal voltage and under the switching of inductive and capacitive loads.
Hybrid-Source Impedance Networks
DEFF Research Database (Denmark)
Li, Ding; Gao, Feng; Loh, Poh Chiang;
2010-01-01
Hybrid-source impedance networks have attracted attention among researchers because of their flexibility in performing buck-boost energy conversion. To date, three distinct types of impedance networks can be summarized for implementing voltage-type inverters with another three types summarized...... for current-type inverters. These impedance networks can in principle be combined into two generic network entities, before multiple of them can further be connected together by applying any of the two proposed generalized cascading concepts. The resulting two-level and three-level inverters implemented using...... the cascaded networks would have a higher output voltage gain and other unique advantages that currently have not been investigated yet. It is anticipated that these advantages would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually...
Three level MV converter using series connected IGBT's
DEFF Research Database (Denmark)
Munk-Nielsen, Stig; Vaerens, M.C.P.; Sundvall, J.
2009-01-01
A simple method of serial connecting IGBT's is applied and standard low voltage IGBT modules are used in the MV test inverter to evaluate the method. The dc link voltage is 2.4 kV and the RMS output line to line voltage is 1.7kV. The method works and test experiences are presented in paper....
Using Averaged Modeling for Capacitors Voltages Observer in NPC Inverter
Directory of Open Access Journals (Sweden)
Bassem Omri
2012-01-01
Full Text Available This paper developed an adaptive observer to estimate capacitors voltages of a three-level neutral-point-clamped (NPC inverter. A robust estimated method using one parameter is proposed, which eliminates the voltages sensors. An averaged modeling of the inverter was used to develop the observer. This kind of modeling allows a good trade-off between simulation cost and precision. Circuit model of the inverter (implemented in Simpower Matlab simulator associated to the observer algorithm was used to validate the proposed algorithm.
DEFF Research Database (Denmark)
Siwakoti, Yam P.; Town, Graham; Loh, Poh Chiang;
2014-01-01
higher boost, the inverter can operate at a higher modulation index, thereby minimizing switching device stress and providing better output power quality. In addition, the inverter has more degrees of freedom for setting the voltage gain and modulation index than other classical impedance-source networks......This paper introduces a new 3-phase Y-source inverter whose gain is presently not matched by classical impedance-network-based inverters operating at the same duty ratio. The proposed network uses a tightly coupled transformer with three windings. By squeezing the shoot-through range while keeping...
A Tapped-Inductor Buck-Boost Converter for a Dielectric ElectroActive Polymer Generator
DEFF Research Database (Denmark)
Dimopoulos, Emmanouil; Munk-Nielsen, Stig
2014-01-01
Energy harvesting applications based on Dielectric ElectroActive Polymer (DEAP) generators have been in the spotlight in recent years after the latter ones’ documented advantages against competing electromagnetic and field-activated technologies. Yet, the need for bidirectional energy flow under...
Analysis of current-bidirectional buck-boost based switch-mode audio amplifier
DEFF Research Database (Denmark)
Bolten Maizonave, Gert; Andersen, Michael A. E.; Kjærgaard, Claus;
2011-01-01
in a differential mode buckbased amplifier with a boost converter as power supply. The averaged switch modelling of the differential mode current bidirectional topology is also used, in order to analyze the steady state and frequency-wise behaviour of this converter and parameterize it to meet the design criteria....... Next, several piecewise-linear siimulation resultss are shown with detail enough to emphasize the features of the converter. A simple prototype is implemented to verify the main predicted features. Presently no previous publicat ion could be found containing a thorough analysis of this topology...
Superradiant phase transitions with three-level systems
Baksic, Alexandre; Ciuti, Cristiano
2013-01-01
We determine the phase diagram of $N$ identical three-level systems interacting with a single photonic mode in the thermodynamical limit ($N \\to \\infty$) by accounting for the so-called diamagnetic term and the inequalities imposed by the Thomas-Reich-Kuhn (TRK) oscillator strength sum rule. The key role of transitions between excited levels and the occurrence of first-order phase transitions is discussed. We show that, in contrast to two-level systems, in the three-level case the TRK inequalities do not always prevent a superradiant phase transition in presence of a diamagnetic term.
A Three-level 4 x 3 Conventinal Matrix Converter
DEFF Research Database (Denmark)
Rong, Runjie; Loh, Poh Chiang; Wang, Peter;
2007-01-01
This paper proposes a topology of a three-level 4 × 3 conventional matrix converter with 12 bi-directional switches. PWM control and modulation index compensation have been investigated. Operation theory has been verified by the simulation results using Matlab. The simulation results show that th...
On hybrid states of two and three level atoms
Billionnet, C.
2005-01-01
We calculate atom-photon resonances in the Wigner-Weisskopf model, admitting two photons and choosing a particular coupling function. We also present a rough description of the set of resonances in a model for a three-level atom coupled to the photon field. We give a general picture of matter-field resonances these results fit into.
Exploration and Planning in a Three-Level Cognitive Architecture
DEFF Research Database (Denmark)
Kraft, Dirk; Baseski, Emre; Popovic, Mila;
2008-01-01
We describe an embodied cognitive system based on a three-level architecture that includes a sensorimotor layer, a mid-level layer that stores and reasons about object-action episodes, and a high-level symbolic planner that creates abstract action plans to be realised and possibly further specifi...
An EMTDC Model of a Three Level four MVAR Compensator
DEFF Research Database (Denmark)
Rasmussen, Tonny Wederberg
1997-01-01
The paper discusses the dynamic characteristics of a three level ±4mvar solid state var compensator which is built and will be used for dynamic reactive power compensation in a wind farm. An investigation has been carried out of the influence of the compensator reactor, the DC intermediate voltag...
Energy Technology Data Exchange (ETDEWEB)
Zhao, Zilai [General Motors LLC, Detroit, MI (United States); Gough, Charles [General Motors LLC, Detroit, MI (United States)
2016-04-22
The goal of this Cooperative Agreement was the development of a Next Generation Inverter for General Motors’ electrified vehicles, including battery electric vehicles, range extended electric vehicles, plug-in hybrid electric vehicles and hybrid electric vehicles. The inverter is a critical electronics component that converts battery power (DC) to and from the electric power for the motor (AC).
Energy Technology Data Exchange (ETDEWEB)
Zhao, Zilai; Gough, Charles
2016-01-15
The goal of this Cooperative Agreement was the development of a Next Generation Inverter for General Motors’ electrified vehicles, including battery electric vehicles, range extended electric vehicles, plug-in hybrid electric vehicles and hybrid electric vehicles. The inverter is a critical electronics component that converts battery power (DC) to and from the electric power for the motor (AC).
Illustrating Polymerization using Three-level Model Fusion
Kolesar, Ivan; Parulek, Julius; Viola, Ivan; Bruckner, Stefan; Stavrum, Anne-Kristin; Hauser, Helwig
2014-01-01
Research in cell biology is steadily contributing new knowledge about many different aspects of physiological processes like polymerization, both with respect to the involved molecular structures as well as their related function. Illustrations of the spatio-temporal development of such processes are not only used in biomedical education, but also can serve scientists as an additional platform for in-silico experiments. In this paper, we contribute a new, three-level modeling approach to illu...
Interactively illustrating polymerization using three-level model fusion
Kolesar, Ivan; Parulek, Julius; Viola, Ivan; Bruckner, Stefan; Stavrum, Anne-Kristin; Hauser, Helwig
2014-01-01
Background Research in cell biology is steadily contributing new knowledge about many aspects of physiological processes, both with respect to the involved molecular structures as well as their related function. Illustrations of the spatio-temporal development of such processes are not only used in biomedical education, but also can serve scientists as an additional platform for in-silico experiments. Results In this paper, we contribute a new, three-level modeling approach to illustrate phys...
Vulnerability of complex networks under three-level-tree attacks
Hao, Yao-hui; Han, Ji-hong; Lin, Yi; Liu, Lin
2016-11-01
We investigate vulnerability of complex networks including model networks and real world networks subject to three-level-tree attack. Specifically, we remove three different three-level-tree structures: RRN (Random Root Node), MaxDRN (Max Degree Root Node) and MinDRN (Min Degree Root Node) from a network iteratively until there is no three-level-tree left. Results demonstrate that random network is more robust than scale-free network against three tree attacks, and the robustness of random network decreases as the increases. And scale-free network shows different characteristics in different tree attack modes. The robustness of scale-free is not affected by the parameters for RRN, but increases as the increases for MinDRN. The important thing is that MaxDRN is the most effective in the three tree attack modes, especially for scale-free network. These findings supplement and extend the previous attack results on nodes and edges, and can thus help us better explain the vulnerability of different networks, and provide an insight into more tolerant real complex systems design.
Directory of Open Access Journals (Sweden)
Nagarathna M
2015-06-01
Full Text Available Solar energy the most efficient, eco-friendly and abundantly available energy source in the nature. It can be converted into electrical energy in cost effective manner. In recent years, the interest in solar energy has risen due to surging oil prices and environmental concern. In many remote or underdeveloped areas, direct access to an electric grid is impossible and a photovoltaic inverter system would make life much simpler and more convenient. With this in mind, it is aimed to design, build, and test a solar panel inverter. This inverter system could be used as backup power during outages, battery charging, or for typical household applications. The main components of this solar system are solar cell, dc to dc boost converters, and inverter. Sine wave push pull inverter topology is used for inverter. In this topology only two MOSFETs are used and isolation requirement between control circuit and power circuit is also less which helps to decrease the cost of solar inverter.
DEFF Research Database (Denmark)
Zhang, Zhe; Anthon, Alexander; Andersen, Michael A. E.
2014-01-01
frequencyincreases due to high switching loss of the equipped high voltagepower switches. In order to reduce switching loss and herebyenhance efficiency, a newly proposed circuit-level decouplingmodulation (CLDM) scheme is applied for these two widely usedthree-phase three-level inverters, as well...... as their correspondingloss analyses are addressed. The switching loss reduction isevaluated comprehensively undervariant modulation indices andload power factors. The analysis results reveal that the CLDM isan alternative discontinuouspulse-width modulation (DPWM)approach for inverters with high switching frequencies...
Ionization characteristics of three-level atoms by nonmonochromatic lasers
International Nuclear Information System (INIS)
Ionization characteristics of two-step excitation by two intense nonmonochromatic (finite bandwidth) lasers are investigated. By approximating the laser fields by a stochastic model of a chaotic field, the stochastic atomic-density-matrix equations for three-level atoms are first obtained. Comparing with the analytical solution, the accuracy of our model is confirmed. By using this model, the ionization characteristics are studied in detail as a function of laser bandwidth. The dependence of laser bandwidth on the Doppler averaged ionization probability is also investigated. (author)
Semistar Invertibility on Integral Domains
Institute of Scientific and Technical Information of China (English)
Marco Fontana; Giampaolo Picozza
2005-01-01
A natural development of the recent work about semistar operations leads to investigate the concept of "semistar invertibility". Here, we show the existence of a "theoretical obstruction" for extending many results, proved for star-invertibility, to the semistar case. For this reason, we introduce two distinct notions of invertibility in the semistar setting (called *-invertibility and quasi-*-invertibility), we discuss the motivations of these "two levels" of invertibility and we extend, accordingly, many classical results proved for the d-, v-, t- and w-invertibility.
Directory of Open Access Journals (Sweden)
Ming-Hung Chen
2015-06-01
Full Text Available This paper describes the design and implementation of three-level power converters for wind-driven permanent-magnet synchronous generators with unbalanced loads. To increase voltage stress and reduce current harmonics in the electrical power generated by a wind generator, a three-phase, three-level rectifier is used. Because a synchronous rotating frame is used on the AC-input side, the use of a neutral-point-clamped controller is proposed to increase the power factor to unity and reduce current harmonics. Furthermore, a novel six-leg inverter is proposed for transferring energy from the DC voltage to a three-phase, four-wire AC source with a constant voltage and a constant frequency. The power converters also contain output transformers and filters for power buffering and filtering, respectively. All three output phase voltages are fed back to control the inverter output during load variations. A digital signal processor is used as the core control device for implementing a 1.5 kV, 75 kW drive system. Experimental data show that the power factor is successfully increased to unity and the total current harmonic distortion is 3.2% on the AC-input side. The entire system can attain an efficiency of 91%, and the voltage error between the upper and lower capacitors is approximately zero. Experimental results that confirm the high performance of the proposed system are presented.
Three-level description of the domino cellular automaton
Czechowski, Zbigniew
2010-01-01
Inspired by the approach of kinetic theory of gases, a three-level description (microscopic, mesoscopic and macroscopic) of cellular automaton is presented. To provide an analytical treatment a simple domino cellular automaton with avalanches was constructed. Formulas concerning exact relations for density, clusters, avalanches and other parameters in an equilibrium state were derived. It appears that some relations are approximately valid for deviations from the equilibrium, so the adequate Ito equation could be constructed. The equation provides the time evolution description of some variable on the macroscopic level. The results also suggest a motive for applying of the procedure of construction of the Ito equation (from time series data) to natural time series.
Consciousness, Mind, and Spirit: Three Levels of Human Cognition
Directory of Open Access Journals (Sweden)
Andrej Ule
2015-10-01
Full Text Available The article elucidates three important concepts and realities that refer to cognitive phenomena and are often (mistakenly used as synonyms: consciousness (slo. zavest, mind (slo. um, and spirit (slo. duh. They present three levels of human cognition: individual-experiential, individual-mental, and trans-individual-mental. Simply put: the concept of consciousness pertains to the waking mental life of a human being, while the concept of mind pertains to the ability and activity to consciously comprehend and understand contents and objects of human activity. I delineate three “types” of spirit: personal spirit, objective spirit, and the objectification of spirit in productions of human culture; I have doubts, however, about the existence of cosmic or super-cosmic dimensions of spirit, although some interpretations of quantum physics and modern cosmology suggest that such dimensions are possible.
Matched Pulse Propagation in a Three-Level System
Park, Q H
1997-01-01
The Bãcklund transformation for the three-level Maxwell-Bloch equation is presented in the matrix potential formalism. By applying the Bãcklund transformation to a constant electric field background, we obtain a general solution for matched pulses (a pair of solitary waves) which can emit or absorb a light velocity solitary pulse but otherwise propagate with their shapes invariant. In the special case, this solution describes a steady state pulse without emission or absorption, and becomes the matched pulse solution recently obtained by Hioe and Grobe. A nonlinear superposition rule is derived from the solitons as well as nonabelian breathers. Various new features of these solutions are addressed. In particular, we analyze in detail the scattering of "invertons", a specific pair of different wavelength solitons one of which moving with the velocity of light. Unlike the usual case of soliton scattering, the broader inverton changes its sign through the scattering. Surprisingly, the light velocity inverton re...
CONSTRUCTING UNIFORM DESIGNS WITH TWO- OR THREE-LEVEL
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
When the number of runs is large, to search for uniform designs in the sense of low-discrepancy is an NP hard problem. The number of runs of most of the available uniform designs is small (≤ 50). In this article, the authors employ a kind of the so-called Hamming distance method to construct uniform designs with two- or three-level such that some resulting uniform designs have a large number of runs. Several infinite classes for the existence of uniform designs with the same Hamming distances between any distinct rows are also obtained simultaneously. Two measures of uniformity, the centered L2-discrepancy (CD, for short) and wrap-around L2-discrepancy (WD, for short), are employed.
A Novel Space Vector Technique for the Direct Three-level Matrix Converter
Directory of Open Access Journals (Sweden)
C. Agees Kumar
2014-10-01
Full Text Available This study proposes a novel Direct Torque Control (DTC method for the Direct Three level Matrix Converter (DTMC, which uses both the input phase voltage vectors (short vectors and the input line voltage vectors (long vectors. The problem of voltage imbalance at the input filter capacitance due to the use of the short vectors is addressed with an additional voltage hysteresis comparator. With the errors of torque, flux, sin Ψ and the neutral point voltage, an Optimum Switching Table (OST is designed for the DTMC. The OST generates the necessary switching signals for the DTC of the DTMC. The DTMC topology with the modified ISVM technique reduces the THD at the output. The proposed DTMC Indirect Space Vector pulse width Modulation (ISVM technique uses the idea of multilevel inverter SVM technique along with the proposed neutral current balancing strategy for generating the firing pulses. The switching loss model for the DTMC is developed and the performance of the DTMC is compared with that of the Conventional Matrix Converter (CMC. The performance of the proposed DTC technique for the DTMC is evaluated through simulation to explain the reduced torque ripple characteristics. To validate the proposed DTMC ISVM technique, a 3 kVA direct multilevel matrix converter prototype was developed.
Energy Technology Data Exchange (ETDEWEB)
Mozaffari Niapour, S.A.KH., E-mail: s.a.kh.mozaffari.niapour@gmail.com [Faculty of Electrical and Computer Engineering, University of Tabriz, 51664 Tabriz (Iran, Islamic Republic of); Danyali, S.; Sharifian, M.B.B.; Feyzi, M.R. [Faculty of Electrical and Computer Engineering, University of Tabriz, 51664 Tabriz (Iran, Islamic Republic of)
2011-08-15
Highlights: {yields} Employing the BLDC motor in water pumping systems. {yields} Utilizing the ZSI as a single-stage power converter in the PV water pumping systems based on BLDC motor. {yields} Improvement of the conventional IC MPPT method with the fuzzy logic control scheme to save more energy from the PV array. {yields} Taking the advantages of the DTC drive of the BLDC motor. {yields} Optimizing the water pumping system speed response characteristic by PSO. - Abstract: This paper discusses operation performance of a water pumping system consist of a brushless dc (BLDC) motor coupled a centrifugal pump and accompanying a Z-source inverter (ZSI) fed by a photovoltaic (PV) array, to be improved. Despite conventional double-stage power converters, this paper proposes utilizing a single-stage ZSI to extract the maximum power of the PV array and supply the BLDC motor simultaneously. Utilizing the ZSI provides some inherent advantages such as high efficiency and low cost, which is very promising for PV systems due to its novel voltage buck/boost capability. In addition, in order to precisely perform the maximum power point tracking (MPPT) of the PV array the fuzzy logic-incremental conductance (FL-IC) MPPT scheme is proposed. The proposed FL-IC MPPT scheme provides enough modification to the conventional IC method to enjoy an appropriate variable step size MPPT control signal for the ZSI. Moreover, direct torque control (DTC) is found more effective in comparison with hysteresis current control with current shaping to drive the BLDC motor, because it benefits from faster torque response, reduced torque ripple, less sensitivity to parameters variations, and simple implementation. In the mean time, due to the frequently variations of the PV power generation; delivered mechanical power to the centrifugal pump is variable. Thus, the BLDC motor should be driven with variable reference speed. In order to improve the speed transient response of the BLDC motor and enhance
Stabilization of invert emulsions
Energy Technology Data Exchange (ETDEWEB)
Agishev, M.Kh.
1978-10-01
The technology is given for developing emulsifier-salts of diethylenetriamine and oxidized waste products during the production of fatty acids in order to make invert emulsions that are used in the drilling of oil wells. 6 references, 3 figures, 1 table
Rippel, W. E.; Edwards, D. B.
1984-01-01
Commutation by field-effect transistor allows more efficient operation. High voltage field-effect transistor (FET) controls silicon controlled rectifiers (SCR's). Circuit requires only one capacitor and one inductor in commutation circuit: simpler, more efficient, and more economical than conventional inverters. Adaptable to dc-to-dc converters.
DEFF Research Database (Denmark)
Anthon, Alexander
their trade-offs. The contributions are: • Comprehensive loss analysis and identification of major loss contributors within T-Type converter topology operating in inverter and rectifier context. • Evaluation of the use and loss benefits of Silicon Carbide switching devices in the T-Type structure...
Green power inverter. Test report; Green power inverter. Proevningsrapport
Energy Technology Data Exchange (ETDEWEB)
Poulsen, Soeren; Katic, I.
2004-10-01
The report contains Danish Technological Institute's contribution to measurements carried out in connection with the PSO project 'Green Power Inverter'. During the project a module inverter for photovoltaic plants has been developed, i.e. an inverter designed to be installed on every single solar cell module. The objective of the measurements has been to do an independent verification of the inverters yield and compare the results to State-of-the-Art on this area. Therefore an analysis of two commercial solar cell inverters in the same power range has been carried through. (BA)
Inverting the Linear Algebra Classroom
Talbert, Robert
2014-01-01
The inverted classroom is a course design model in which students' initial contact with new information takes place outside of class meetings, and students spend class time on high-level sense-making activities. The inverted classroom model is so called because it inverts or "flips" the usual classroom design where typically class…
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Blaabjerg, Frede; Loh, Poh Chiang
2015-01-01
This paper introduces a new inverter topology called a “quasi-Y-source inverter”. The proposed inverter inherits all the advantages of the original Y-source inverter. In addition, the new topology draws continuous current from the source which is required for many renewable sources. It also has d...
DEFF Research Database (Denmark)
Blaabjerg, Frede; Loh, Poh Chiang; Gao, F.
2008-01-01
input source and inverter bridge. This impedance network allows the output end of a voltage-type Z-source inverter to be shorted for voltage-boosting without causing a large current flow, and the terminal current of a current-type inverter to be interrupted for current boosting without introducing over...... since an added filter will raise the system cost, and at times can complicate the dynamic tuning and resonant consideration of the inverters. The same embedded concept can also be used for designing a full range of voltage and current-type inverters with each of them tested experimentally using a number...
DEFF Research Database (Denmark)
Chiang Loh, Poh; Gao, Feng; Blaabjerg, Frede
2010-01-01
input source and inverter bridge. This impedance network allows the output end of a voltage-type Z-source inverter to be shorted for voltage boosting without causing a large current flow and the terminal current of a current-type inverter to be interrupted for current boosting without introducing...... is a favorable advantage, since an added filter will raise the system cost and, at times, can complicate the dynamic tuning and resonant consideration of the inverters. The same embedded concept can also be used for designing a full range of voltage- and current-type inverters with each of them...
Inverted organic photovoltaic cells.
Wang, Kai; Liu, Chang; Meng, Tianyu; Yi, Chao; Gong, Xiong
2016-05-21
The advance in lifestyle, modern industrialization and future technological revolution are always at high expense of energy consumption. Unfortunately, there exist serious issues such as limited storage, high cost and toxic contamination in conventional fossil fuel energy sources. Instead, solar energy represents a renewable, economic and green alternative in the future energy market. Among the photovoltaic technologies, organic photovoltaics (OPVs) demonstrate a cheap, flexible, clean and easy-processing way to convert solar energy into electricity. However, OPVs with a conventional device structure are still far away from industrialization mainly because of their short lifetime and the energy-intensive deposition of top metal electrode. To address the stability and cost issue simultaneously, an inverted device structure has been introduced into OPVs, bridging laboratory research with practical application. In this review, recent progress in device structures, working mechanisms, functions and advances of each component layer as well their correlations with the efficiency and stability of inverted OPVs are reviewed and illustrated.
Inverted organic photovoltaic cells.
Wang, Kai; Liu, Chang; Meng, Tianyu; Yi, Chao; Gong, Xiong
2016-05-21
The advance in lifestyle, modern industrialization and future technological revolution are always at high expense of energy consumption. Unfortunately, there exist serious issues such as limited storage, high cost and toxic contamination in conventional fossil fuel energy sources. Instead, solar energy represents a renewable, economic and green alternative in the future energy market. Among the photovoltaic technologies, organic photovoltaics (OPVs) demonstrate a cheap, flexible, clean and easy-processing way to convert solar energy into electricity. However, OPVs with a conventional device structure are still far away from industrialization mainly because of their short lifetime and the energy-intensive deposition of top metal electrode. To address the stability and cost issue simultaneously, an inverted device structure has been introduced into OPVs, bridging laboratory research with practical application. In this review, recent progress in device structures, working mechanisms, functions and advances of each component layer as well their correlations with the efficiency and stability of inverted OPVs are reviewed and illustrated. PMID:27087582
Inverted organic photosensitive device
Energy Technology Data Exchange (ETDEWEB)
Forrest, Stephen R.; Tong, Xiaoran; Lee, Jun Yeob; Cho, Yong Joo
2015-09-08
There is disclosed a method for preparing the surface of a metal substrate. The present disclosure also relates to an organic photovoltaic device including a metal substrate made by such method. Also disclosed herein is an inverted photosensitive device including a stainless steel foil reflective electrode, an organic donor-acceptor heterojunction over the reflective electrode, and a transparent electrode over the donor-acceptor heterojunction.
A Three Level Autonomous Software System for Increased Science Return
Robinson, P. I.; Mancinelli, R. L.; Landheim, R.
2005-12-01
The development of smart science instruments for autonomous operation (on Earth or in space) has the potential to increase science return and reduce the risk of experiment failure. When researchers are confronted with unexpected data/results of the experimental test system, they must determine whether the experimental setup has failed, or scientific discovery is being made. These two classes of events could have the same time series signature. To directly address this issue, we have developed a three-level software system referred to as E3, which consists of an engineering level, an experiment level, and an executive level. Each level of the software system is designed in a modular fashion using model based feedback controllers. The same feedback control mechanism is used for each level; the model itself determines the level. To determine if failure of the experimental setup can explain the data/results, researchers run calibration tests for hardware (e.g., sensors and actuators) as well as verify that the software (e.g., controls and analog to digital conversion routines) is running as planned. If anomalies are found, then modifications are made to the experimental setup, or the anomaly is accepted as the new baseline state of the instrument. The engineering level of the E3 software system is responsible for this process. To determine if scientific discovery, as opposed to failure, can explain the data/results, a researcher tries to explain the difference between the observed and expected results. These explanations are terms of the basic processes of nature to determine the rate limiting step(s) of a complex set of processes, where the flux could be due to heat transfer, mass transfer, momentum transfer, or chemical reaction processes. Once the differences are understood, modifications are made to the software control of the experiment, as well as to the model the researcher is building over the course of repeated experiments. The experiment level of the E3
Energy Technology Data Exchange (ETDEWEB)
Blackmon, J.B.
1979-07-01
Implications of employing a non-inverting heliostat design with a lower capital cost relative to an inverting design are considered from three standpoints: (1) effects of dust buildup, corresponding cleaning frequencies, and resultant cleaning costs; (2) effects of hail impact; and (3) refleccted beam safety issues. It is concluded that elimination of the inverting stow hardware and addition of reflector area in the slot required for inverting the reflector provides a direct subsystem cost savings. Since the non-inverting heliostat must be stowed face-up during high winds, reflectance degradation rates due to dust buildup are increased. The economic optimum cleaning frequency and allowed loss of reflectance due to dust buildup are determined so as to minimize the total system cost, and it is found that an overall cost savings of 12-13 percent results if the inverting capability is eliminated. Hail impact damage and probability of occurrence for the United States are determined within the accuracy of available data. Analysis indicates that the commercial heliostat laminate glass design considered will survive 1 1/2 inch hailstones and is suitable for installation over most of the US with low to negligible risk from hail damage. Reflected beam safety hazards are analyzed for the non-inverting design relative to the inverting design. No compelling reason is found to require an inverting stow capability, and therefore, a non-inverting stow heliostat is concluded to be a viable, cost-effective option.
Inverted Pendulum Swing Up Controller
Kennedy, David; Conlon, James
2011-01-01
The inverted pendulum is a classic control problem. The system is open – loop unstable and continuously wants to reach equilibrium by falling over. The system must be stabilised by means of feedback. The developed inverted pendulum system is shown in Figure 1. In order to balance the pendulum in the inverted position the pivot must be moved continuously to correct the falling pendulum. This is similar to trying to vertically balance a broom on your hand. This interesting control problem is...
Gas cooled traction drive inverter
Energy Technology Data Exchange (ETDEWEB)
Chinthavali, Madhu Sudhan
2016-04-19
The present invention provides a modular circuit card configuration for distributing heat among a plurality of circuit cards. Each circuit card includes a housing adapted to dissipate heat in response to gas flow over the housing. In one aspect, a gas-cooled inverter includes a plurality of inverter circuit cards, and a plurality of circuit card housings, each of which encloses one of the plurality of inverter cards.
Applications of cascade multilevel inverters
Institute of Scientific and Technical Information of China (English)
彭方正; 钱照明
2003-01-01
Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own de ca-pacitor. The new inverter can : ( 1 ) generate almost sinusoidal waveform voltage while only switching one timeper fundamental cycle ; (2) dispense with multi-pulse inverters' transformers used in conventional utility in-terfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features,feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical,simulated, and experimental results demonstrated the superiority of the new inverters.
Applications of cascade multilevel inverters
Institute of Scientific and Technical Information of China (English)
彭方正; 钱照明
2003-01-01
Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own dc capacitor. The new inverter can: (1) generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle; (2) dispense with multi-pulse inverters' transformers used in conventional utility interfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features, feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical, simulated, and experimental results demonstrated the superiority of the new inverters.
Comparison of Modulation Techniques for Multilevel Inverter fed Permanent Magnet Synchronous Motor
Directory of Open Access Journals (Sweden)
V. NAGA BHASKAR REDDY
2010-10-01
Full Text Available Multilevel inversion is a power conversion strategy in which the output voltage is obtained in steps thus bringing the output closer to a sine wave and reduces the Total Harmonic Distortion. Multilevel inverter structures have been developed to overcome shortcomings in solid-state switching device ratings so that they can be applied to higher voltage systems. In recent years, the multilevel inverters have drawn tremendous interest in the area of high-power medium-voltage energy control. Three different topologies have been proposed for multilevel inverters like Diode-Clamped Inverter, Capacitor Clamped Inverter and Cascaded Multi cell Inverter. In addition, several modulation and control strategies have been developed or adopted for multilevel inverters including the following multilevel Sinusoidal Pulse Width Modulation (SPWM, and Space Vector Modulation. In this paper, simulation of various modulating techniques i.e., Pulse Width Modulate techniques such as Sinusoidal PWM, Trapezoidal PWM, Stepped PWM, Stair case PWM, third harmonicinjected PWM, Modified SVPWM are applied for both Diode Clamped Three-Level Inverter and Diode Clamped Five-Level Inverter, and Space Vector PWM technique are analyzed for DC3LI. The best modulationtechnique are extended to Permanent Magnet Synchronous Motor.
Probabilistic Teleportation of an Unknown Two-Particle Three-Level Entangled State
Institute of Scientific and Technical Information of China (English)
戴宏毅; 李承祖; 陈平行
2004-01-01
We propose a scheme to teleport probabilistically an unknown two-particle three-level entangled state by using two partial entangled two-particle three-level states as the quantum channel. This scheme can be directly generalized to teleport an unknown N-particle three-level entangled state by using N partial-entangled two-particle three-level states as the quantum channel.
Generation of the nonlocal quantum entanglement of three three-level particles by local operations
Institute of Scientific and Technical Information of China (English)
Jin Xing-Ri; Zhang Ying-Qiao; Jin Zhe; Zhang Shou
2005-01-01
We propose a scheme to realize the nonlocal quantum entanglement of three three-level particles by using a three-particle entangled state of three levels as a quantum channel with the aid of some local unitary transformations. This scheme can be directly generalized to the nonlocal quantum entanglement of N three-level particles.
Simplified High-Power Inverter
Edwards, D. B.; Rippel, W. E.
1984-01-01
Solid-state inverter simplified by use of single gate-turnoff device (GTO) to commutate multiple silicon controlled rectifiers (SCR's). By eliminating conventional commutation circuitry, GTO reduces cost, size and weight. GTO commutation applicable to inverters of greater than 1-kilowatt capacity. Applications include emergency power, load leveling, drives for traction and stationary polyphase motors, and photovoltaic-power conditioning.
Simulation of inverter dominated minigrids
Energy Technology Data Exchange (ETDEWEB)
Engler, A.; Osika, O. [Inst. fuer Solare Energieversorgungstechnik (ISET) e.V., Kassel (Germany)
2003-07-01
In order to assess the load flow, the transient behaviour and the stability of inverter dominated minigrids, a model for inverters and a transmission system has been developed. The inverters are represented by a frequency and voltage controlled three phase voltage source and the transmission systems consists of switches, overhead lines ({pi}-equivalent), transformers and a load. The inverters operate in parallel via the MV-distribution system and supply an active load. The contribution of each inverter is determined by the setting of the applied droops (similar to conventional power plants). Furthermore an approach for stability assessment of such systems is introduced. This research work is related to the EC-funded project MicroGrids. (orig.)
Institute of Scientific and Technical Information of China (English)
郭强; 刘和平; 彭东林
2015-01-01
Considering the tougher standards on operation temperature and reliability, an electric vehicle ( EV) motor drive system based on current-fed trans-Z source inverter was presented. The inverter is a single-stage topology, which has Buck-Boost characteristic and achieves bidirectional power flow. The drive system can overcome the drawbacks of the traditional EV drives. It can realize output voltage range from 0 to any times of battery voltage,requires no DC bus capacitors, and provides sinusoidal voltage out-put to the motor, reduces the inverter cost and the failure rate. The different operation states and the e-quivalent circuits of the system were elaborated. The mapping relationship of multi-degrees of control freedom between duty ratios of open-zero states, non-open states and DC-link voltage gain was estab-lished. The available range for different operation modes was discussed, and ac voltage of inverter versus modulation index and power factor was clarified. A prototype of current-fed trans-Z-source inverter was built,the experimental results were presented to verify the theoretical analysis.%鉴于对电动汽车驱动系统运行温度及可靠性的严格要求，提出基于高性能电流型trans-Z源逆变器电机驱动系统，其拓扑是一种具有升-降压功能的单级逆变器，具有能量双向流动的特点。该系统能够克服传统驱动系统中缺点与不足：具有输出电压的任意升-降压功能；无需直流母线电容，提供正弦驱动电压，同时降低了硬件成本、提高了整个驱动系统的可靠性。文中详细分析了系统工作原理并推导出不同运行模式的等效电路，建立多自由度控制下直通零状态、开路零状态与直流链电压增益的映射关系；明确了系统在不同模式下的运行范围，量化逆变器输出电压与控制变量及功率因数之间的关系。最后通过实验验证了理论分析的正确性与实用性。
Transformerless PV inverters. Final report
Energy Technology Data Exchange (ETDEWEB)
Borup, U.
2009-12-15
Since the start of the project the market for grid connected PV inverters have developed further. When the project started three - phase inverter were only available in high power systems. The technology developed within this project will enable three phase technology also to be implemented in string inverters for system down to 10 kW. We expect this to be very attractive due to the increased demand for symmetrical feed-in to the grid. The project relevance is therefore high and the sector continues to develop very much driven by technology. Especially the inverter technology is getting a lot of focus. The inverter systems are expected to take a much larger role in supporting the electrical grid in the future. The technology platform developed within the project is prepared to be extended with these utility functionalities. The main results of the project were: 1) A new technology concept for transformer-less inverters has been demonstrated with a number of prototypes. 2) Efficiency above 97,7% has been proven. 3) Efficiency and Maximum power point tracking has been optimized to ensure that almost all energy produced of the panels is transferred to the grid. 4) The platform is developed with a very fast control board, which enables extended functionality as demanding grid supporting functions in the future. Details about cost price and details about the control loop implementation is excluded from the report due to the competitive situation for Danfoss Solar Inverters A/S. (LN)
Energy Technology Data Exchange (ETDEWEB)
Lee, H. [Kyungnam University (Korea, Republic of)
1996-10-27
A soft switching method with small switching loss was proposed for the purpose of increasing the efficiency of a DC-DC boost converter which converted a DC current generated by solar cells to a variable DC current. Existing current converters are supplemented by using a snubber circuit around the switch so as to protect the switch by a hard switching action. However, with an increase of the output current, snubber loss is increased, reducing the efficiency. In order to solve this problem, the partial resonant switch method was applied to the converter; with this method of partially forming a resonant circuit only at the time of turning on/off of the switch, the switching loss was reduced through the soft switching, thereby making the proposed converter operate with high efficiency. Moreover, the resonant element of the partial resonant circuit using a snubber condenser, the energy accumulated in the condenser was regenerated on the power supply side without loss of snubber. With the regenerated energy, the proposed converter was provided with a smaller ratio of switching to use than the conventional converter. 4 refs., 7 figs., 1 tab.
Latha. S. C; Dr. Venugopal .N
2014-01-01
The portable devices development of semiconductor manufacturing technology, conversion efficiency, power consumption, and the size of devices have become the most important design criteria of switching power converters. For portable applications better conveniences extension of battery life and improves the conversion efficiency of power converters .It is essential to develop accurate switching power converters, which can reduce more wasted power energy. The proposed topology can ...
Directory of Open Access Journals (Sweden)
Latha. S. C
2014-11-01
Full Text Available The portable devices development of semiconductor manufacturing technology, conversion efficiency, power consumption, and the size of devices have become the most important design criteria of switching power converters. For portable applications better conveniences extension of battery life and improves the conversion efficiency of power converters .It is essential to develop accurate switching power converters, which can reduce more wasted power energy. The proposed topology can achieve faster transient responses when the supply voltages are changed for the converter by making use of the feed forward network .With mode select circuit the conduction & switching losses are reduced the positive buck–boost converter operate in buck, buck–boost, or boost converter. By adding feed-forward techniques, the proposed converter can improve transient response when the supply voltages are changed. The designing, modeling & experimental results were verified in MATLAB/ Simulink. The fuzzy logic controller is used as controller.
Detecting and mitigating inverter aging
International Nuclear Information System (INIS)
Nuclear power plants use inverters to supply power to safety-related equipment, instrumentation, and controls. They convert direct current (dc) to alternating current (ac) power, thereby making low voltage ac power available even under a station blackout condition. As part of the U.S. NRC's nuclear plant aging research (NPAR) program, the operating experience of this equipment has been analyzed to determine the dominant failure modes and causes. This paper summarizes that data, and then describes methods which can be employed to detect inverter degradation prior to failure, as well as methods to minimize the failure effects. In both cases, the mitigation of inverter aging is emphasized
Institute of Scientific and Technical Information of China (English)
DAIHong-Yi; KUANGLe-Man; LICheng-Zu
2005-01-01
We propose a scheme to probabilistically teleport an unknown arbitrary three-level two-particle state by using two partial entangled two-particle states of three-level as the quantum channel. The classical communication cost required in the ideal probabilistic teleportation process is also calculated. This scheme can be directly generalized to teleport an unknown and arbitrary three-level K-particle state by using K partial entangled two-particle states of three-level as the quantum channel.
Directory of Open Access Journals (Sweden)
Jelena Loncarski
2015-04-01
Full Text Available The standard solution for the traction system in battery powered electric vehicles (EVs is a two-level (2L inverter feeding a three-phase motor. A simple and effective way to achieve a three-level (3L inverter in battery-supplied electric vehicles consists of using two standard three-phase 2L inverters with the open-end winding connection of standard three-phase ac motors. The 3L inverter solution can be usefully adopted in EVs since it combines several benefits such as current ripple reduction, increment of phase motor voltage with limited voltage ratings of the two battery banks, improvement in system reliability, etc. The reduction in current ripple amplitude is particularly relevant since it is a source of electromagnetic interference and audio noise from the inverter-motor power connection cables and from the motor itself. By increasing the inverter switching frequency the ripple amplitude is reduced, but the drive efficiency decreases due to the proportionally increased switching losses. In this paper the peak-to-peak ripple amplitude of the dual-2L inverter is evaluated and compared with the corresponding ripple of the single-2L inverter, considering the same voltage and power motor ratings. The ripple analysis is carried out as a function of the modulation index to cover the whole modulation range of the inverter, and the theoretical results are verified with experimental tests carried out by an inverter-motor drive prototype.
DEFF Research Database (Denmark)
Loh, Poh Chiang; Li, Ding; Blaabjerg, Frede
2013-01-01
Voltage-type Γ-Z-source inverters are proposed in this letter. They use a unique Γ-shaped impedance network for boosting their output voltage in addition to their usual voltage-buck behavior. Comparing them with other topologies, the proposed inverters use lesser components and a coupled transfor......Voltage-type Γ-Z-source inverters are proposed in this letter. They use a unique Γ-shaped impedance network for boosting their output voltage in addition to their usual voltage-buck behavior. Comparing them with other topologies, the proposed inverters use lesser components and a coupled...... transformer for producing the high-gain and modulation ratio simultaneously. The obtained gain can be tuned by varying the turns ratio γΓZ of the transformer within the narrow range of 1 <; γΓZ ≤ 2. This leads to lesser winding turns at high gain, as compared to other related topologies. Experimental testing...
Inverter Ground Fault Overvoltage Testing
Energy Technology Data Exchange (ETDEWEB)
Hoke, Andy [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nelson, Austin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Chakraborty, Sudipta [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Chebahtah, Justin [SolarCity Corporation, San Mateo, CA (United States); Wang, Trudie [SolarCity Corporation, San Mateo, CA (United States); McCarty, Michael [SolarCity Corporation, San Mateo, CA (United States)
2015-08-12
This report describes testing conducted at NREL to determine the duration and magnitude of transient overvoltages created by several commercial PV inverters during ground fault conditions. For this work, a test plan developed by the Forum on Inverter Grid Integration Issues (FIGII) has been implemented in a custom test setup at NREL. Load rejection overvoltage test results were reported previously in a separate technical report.
THD Reduction in Performance of Cascaded Multi-Level Inverter Fed Induction Motor Drive
Directory of Open Access Journals (Sweden)
Naveen Kumar Verma
2013-12-01
Full Text Available The multilevel inverter power structure plays a vital role in the power industry. It is easier to produce a high-power, high-voltage inverter with the multilevel structure. The topologies of multilevel inverter have several advantages such as lower total harmonic distortion (THD, lower electromagnetic interference (EMI generation, reduction of voltage ratings of the power semiconductor switching devices and high output voltage. This paper presents a universal control scheme based on multicarrier PWM methods and its implementation in three-level, five-level and nine-level cascaded inverters feeding a three phase induction motor. This paper compares total harmonic distortion values of voltage and current waveforms of induction motors between different levels.
SIMPLIFIED SVPWM ALGORITHM BASED DIODE CLAMPED 3-LEVEL INVERTER FED DTC-IM DRIVE
Directory of Open Access Journals (Sweden)
C. HARI KRISHNA
2012-05-01
Full Text Available This paper presents a simplified space vector pulse width modulation (SVPWM based diode clamped threelevel inverter fed direct torque controlled (DTC induction motor drive. The space vector diagram of three-level inverter is simplified into two-level inverter. So the selection of switching sequences is done as conventional two-level SVPWM method. Thus, the proposed algorithm reduces the complexity involved in the PWM algorithm. To validate the proposed PWM lgorithm, several simulation studies have been carried and resultsare presented. From the results, it can be observed that the proposed algorithm reduces the total harmonic distortion (THD of the line current and line voltages when compared with the 2-level inverter fed induction motor drive.
Control and Modeling of Push-Pull Forward Three-Level Converter for Microgrid
DEFF Research Database (Denmark)
Yao, Zhilei; Xu, Jing; Guerrero, Josep M.
2015-01-01
Renewable energy sources are widely used in microgrid. Output voltage of them is often low and varies widely. Because diodes in three-level legs in traditional three-level (TL) converter are substituted by MOSFETs, the push-pull forward (PPF) TL converter is very suitable for wide and low...
Grid Connected WECS with A Five Level DCMLI using PID Controller
Directory of Open Access Journals (Sweden)
G.Balaji
2014-07-01
Full Text Available This paper deals with the analysis, modeling and control system for permanent magnet synchronous generator (PMSG based wind turbine connected to the grid. A wind energy conversion using DC-DC Buck- Boost Converter for permanent magnet synchronous generator (PMSG based variable speed wind energy conversion system (WECS has been proposed which is integrated with grid using five-level diode clamped multilevel (DCMLI inverter. In this work the instantaneous values of input side current and voltage of DC-DC buck-boost converter are utilized for implementing the PID controller. The proposed work is verified by the simulation in Powersim.
Directory of Open Access Journals (Sweden)
Rashmi S
2014-03-01
Full Text Available This paper proposes the Dynamic modeling and performance analysis of Permanent magnet synchronous generator (PMSG based Wind Generation System (WGS. This system consists of Wind Turbine, PMSG, Diode Rectifier, Buck- Boost converter, Voltage source Inverter (VSI. PMSG and Buck Boost converter are employed in WGS to get efficient output according to the load requirement without damaging the system. The output of the VSI is injected to the grid and used for Home Application. The proposed model dynamic simulation results are tested in MATLAB Simulink
Simplified design of switching power supplies
Lenk, John
1996-01-01
Simplified Design of Switching Power Supplies is an all-inclusive, one-stop guide to switching power-supply design. Step-by-step instructions and diagrams render this book essential for the student and the experimenter, as well as the design professional.Simplified Design of Switching Power Supplies concentrates on the use of IC regulators. All popular forms of switching supplies, including DC-DC converters, inverters, buck, boost, buck-boost, pulse frequency modulation, pulse width modulation, current-mode control and pulse skipping, are described in detail. The design examples may
Directory of Open Access Journals (Sweden)
P.Saravanan
2013-05-01
Full Text Available The total harmonic distortion is the major problem in cascaded multilevel inverters. Compared to the three level voltage source inverters, the step-wise output voltage is a major advantage of multilevel inverters. In phase I, the minimization of THD with reduced number of switches using genetic algorithm(GA in a cascaded multilevel inverter with common H-bridge is used. The selective harmonic elimination pulse width modulation technique(SHEPWM has been applied to cascaded multilevel inverter to eliminate lower order harmonics.THD value is minimized by using minimization of total harmonic distortion (MTHD technique in an eleven level cascaded multilevel inverter with common H-bridge and also the harmonics upto 13th order will be reduced. In phase II, a cascaded multilevel inverter with common H-bridge is implemented in the shunt active filter for further reduction of THD and also for load current compensation. A photovoltaic cell is used as a continuous source of energy. Simulation and performance is verified by using MATLAB/Simulink.
Analytic solution and pulse area theorem for three-level atoms
Shchedrin, Gavriil; O'Brien, Chris; Rostovtsev, Yuri; Scully, Marlan O.
2015-12-01
We report an analytic solution for a three-level atom driven by arbitrary time-dependent electromagnetic pulses. In particular, we consider far-detuned driving pulses and show an excellent match between our analytic result and the numerical simulations. We use our solution to derive a pulse area theorem for three-level V and Λ systems without making the rotating wave approximation. Formulated as an energy conservation law, this pulse area theorem can be used to understand pulse propagation through three-level media.
A control strategy for a three-level unified power quality conditioner
Monteiro, Luís F. C.; Costa, José C. C.; Aredes, Maurício; Afonso, João L.
2005-01-01
In this work a control strategy for a three-level Unified Power Quality Conditioner (UPQC) is introduced. Basically, this control strategy is based on the set of active and non-active (reactive) power definitions in the time domain, which have been proposed by Fryze in the 30´s of the last century. The goal of this work consists in expand this control strategy to deal with three-level converters. The use of three-level converters allows a better performance of the equipment, by reducing...
Control and Modeling of Push-Pull Forward Three-Level Converter for Microgrid
Yao, Zhilei; Xu, Jing; Josep M. Guerrero
2015-01-01
Renewable energy sources are widely used in microgrid. Output voltage of them is often low and varies widely. Because diodes in three-level legs in traditional three-level (TL) converter are substituted by MOSFETs, the push-pull forward (PPF) TL converter is very suitable for wide and low inputvoltage applications. It can operate at two-level and three-level modes. Modeling of the proposed converter is established. Control of the proposed converter is designed, which contains output voltage l...
Schemes for Probabilistic Teleportation of an Unknown Three-Particle Three-Level Entangled State
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
In this paper, two schemes for teleporting an unknown three-particle three-level entangled state are proposed. In the first scheme, two partial three-particle three-level entangled states are used as the quantum channels, while in the second scheme, three two-particle three-level non-maximally entangled states are employed as quantum channels.It is shown that the teleportation can be successfully realized with certain probability, for both two schemes, if a receiver adopts some appropriate unitary transformations. It is shown also that the successful probabilities of these two schemes are different.
Using a PFET To Commutate an SCR
Edwards, D. B.; Ripple, W. E.
1984-01-01
Accidental turn-on prevented. PFET diverts load current around SCR to prevent false SCR triggering from current and voltage switching transients. New circuit used in all types of single phase and polyphase inverters and in buck-boost-, and flyback regulators.
Accelerating development of advanced inverters :
Energy Technology Data Exchange (ETDEWEB)
Neely, Jason C.; Gonzalez, Sigifredo; Ropp, Michael; Schutz, Dustin
2013-11-01
The high penetration of utility interconnected photovoltaic (PV) systems is causing heightened concern over the effect that variable renewable generation will have on the electrical power system (EPS). These concerns have initiated the need to amend the utility interconnection standard to allow advanced inverter control functionalities that provide: (1) reactive power control for voltage support, (2) real power control for frequency support and (3) better tolerance of grid disturbances. These capabilities are aimed at minimizing the negative impact distributed PV systems may have on EPS voltage and frequency. Unfortunately, these advanced control functions may interfere with island detection schemes, and further development of advanced inverter functions requires a study of the effect of advanced functions on the efficacy of antiislanding schemes employed in industry. This report summarizes the analytical, simulation and experimental work to study interactions between advanced inverter functions and anti-islanding schemes being employed in distributed PV systems.
A High Power Density Three-level Parallel Resonant Converter for Capacitor Charging
Sheng, Honggang
2009-01-01
This dissertation proposes a high-power, high-frequency and high-density three-level parallel resonant converter for capacitor charging. DC-DC pulsed power converters are widely used in military and medical systems, where the power density requirement is often stringent. The primary means for reducing the power converter size has been to reduce loss for reduced cooling systems and to increase the frequency for reduced passive components. Three-level resonant converters, which combine the mer...
Seixas, Mafalda; Melicio, Rui; Mendes, Victor,; Figueiredo, Joao
2014-01-01
This paper is on an offshore wind energy conversion system equipped with full-power three-level converter and permanent magnet synchronous generator. Multi-level converters, namely three-level converters, are limited by unbalance voltage in the direct current link capacitors. A new control strategy for the selection of the output voltage vectors is proposed in order to improve balance of voltage in the capacitors.
Analysis of Subsynchronous Resonance with Three Level Twelve-Pulse VSC based SSSC
Padiyar, KR; Prabhu, Nagesh
2003-01-01
This paper presents the analysis and simulation of a series compensated system with a static synchronous series compensator (SSSC) as a part of the total compensation. The objective is to investigate the subsynchronous resonance (SSR) characteristic of the combined system. The IEEE first benchmark model (FBM) is considered for the analysis. The active series compensation is provided by a three level twelve pulse SSSC. The modelling and control details of a three level voltage source converter...
Advanced Modular Inverter Technology Development
Energy Technology Data Exchange (ETDEWEB)
Adam Szczepanek
2006-02-04
Electric and hybrid-electric vehicle systems require an inverter to convert the direct current (DC) output of the energy generation/storage system (engine, fuel cells, or batteries) to the alternating current (AC) that vehicle propulsion motors use. Vehicle support systems, such as lights and air conditioning, also use the inverter AC output. Distributed energy systems require an inverter to provide the high quality AC output that energy system customers demand. Today's inverters are expensive due to the cost of the power electronics components, and system designers must also tailor the inverter for individual applications. Thus, the benefits of mass production are not available, resulting in high initial procurement costs as well as high inverter maintenance and repair costs. Electricore, Inc. (www.electricore.org) a public good 501 (c) (3) not-for-profit advanced technology development consortium assembled a highly qualified team consisting of AeroVironment Inc. (www.aerovironment.com) and Delphi Automotive Systems LLC (Delphi), (www.delphi.com), as equal tiered technical leads, to develop an advanced, modular construction, inverter packaging technology that will offer a 30% cost reduction over conventional designs adding to the development of energy conversion technologies for crosscutting applications in the building, industry, transportation, and utility sectors. The proposed inverter allows for a reduction of weight and size of power electronics in the above-mentioned sectors and is scalable over the range of 15 to 500kW. The main objective of this program was to optimize existing AeroVironment inverter technology to improve power density, reliability and producibility as well as develop new topology to reduce line filter size. The newly developed inverter design will be used in automotive and distribution generation applications. In the first part of this program the high-density power stages were redesigned, optimized and fabricated. One of the main
Control and design of full-bridge three-level converter for renewable energy sources
DEFF Research Database (Denmark)
Yao, Zhilei; Xu, Jing; Guerrero, Josep M.
2015-01-01
Output voltage of renewable energy sources, such as fuel cell and PV cell, is often low and varies widely with load and environmental conditions. Therefore, the high step-up DC-DC converter is needed between renewable energy sources and the grid-connected inverter. However, voltage stress...
Inverting an Introductory Statistics Classroom
Kraut, Gertrud L.
2015-01-01
The inverted classroom allows more in-class time for inquiry-based learning and for working through more advanced problem-solving activities than does the traditional lecture class. The skills acquired in this learning environment offer benefits far beyond the statistics classroom. This paper discusses four ways that can make the inverted…
Solar Charged Stand Alone Inverter
Directory of Open Access Journals (Sweden)
M.Vasugi
2014-07-01
Full Text Available This paper deals with solar powered stand alone inverter which converts the variable dc output of a photovoltaic solar panel into ac that can be fed to loads. Stand alone inverters are used in systems where the inverter get its energy from batteries charged by photo voltaic arrays. A charge controller limits the rate at which electric current is added to or drawn from electric batteries. This charge discharge controller is needed to prevent the battery from being overcharged or discharged thus prolonging its life. The charge/discharge control is necessary in order to achieve safety and increase the capacity of the battery. The project has been tested according its operational purposes. Maximum power rating of the experimented solar charge controller is 100W according battery capacities. Cost effective solar charge controller has been designed and implemented to have efficient system and much longer battery lifetime. The dc output is given to inverter and then it is supplied to loads. This method is very cheap and cost effective.
21 CFR 184.1859 - Invert sugar.
2010-04-01
... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Invert sugar. 184.1859 Section 184.1859 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1859 Invert sugar. (a) Invert sugar (CAS Reg. No. 8013-17-0) is an...
Security of Invertible Media Authentication Schemes Revisited
Dönigus, Daniel; Endler, Stefan; Fischlin, Marc; Hülsing, Andreas; Jäger, Patrick; Lehmann, Anja; Podrazhansky, Sergey; Schipp, Sebastian; Tews, Erik; Vowe, Sven; Walthart, Matthias; Weidemann, Frederik
Dittmann, Katzenbeisser, Schallhart and Veith (SEC 2005) introduced the notion of invertible media authentication schemes, embedding authentication data in media objects via invertible watermarks. These invertible watermarks allow to recover the original media object (given a secret encryption key), as required for example in some medical applications where the distortion must be removable.
DEFF Research Database (Denmark)
Guo, Xiaoqiang; Cavalcanti, Marcelo C.; Farias, Alexandre M.;
2013-01-01
Modulation strategy is one of the most important issues for three-level neutral-point-clamped inverters in three-phase transformerless photovoltaic systems. A challenge for modulation is how to keep the common-mode voltages constant to reduce the leakage currents. A single-carrier modulation...
Single-electron differential-amplifier/inverter/non-inverter
Hung, K.-M.; Chen, C.-S.; Lin, T.-W.
2006-07-01
This work presents a single-electron differential amplifier (SEDA), inverter, and non-inverter based on the triple single-dopant quantum-dot (TSDQD) configuration, with new structures. The competition between the field-induced and confinement-related shifts in the wavefunction of the quantum dots yields a field-controllable spatial-displacement single-electron transistor. Deeper impurity levels in quantum dots promise a higher operating temperature and higher on/off current ratios. The I- V characteristics of the device, studied using the transfer Hamiltonian approach (THA), show that the ratio of on/off currents is >80 000 and the voltage gain is >4 eV/Ry, where V is the applied voltage.
Physically feasible three-level transitionless quantum driving with multiple Schrödinger dynamics
Song, Xue-Ke; Ai, Qing; Qiu, Jing; Deng, Fu-Guo
2016-05-01
Three-level quantum systems, which possess some unique characteristics beyond two-level ones, such as electromagnetically induced transparency, coherent trapping, and Raman scatting, play important roles in solid-state quantum information processing. Here, we introduce an approach to implement the physically feasible three-level transitionless quantum driving with multiple Schrödinger dynamics (MSDs). It can be used to control accurately population transfer and entanglement generation for three-level quantum systems in a nonadiabatic way. Moreover, we propose an experimentally realizable hybrid architecture, based on two nitrogen-vacancy-center ensembles coupled to a transmission line resonator, to realize our transitionless scheme which requires fewer physical resources and simple procedures, and it is more robust against environmental noises and control parameter variations than conventional adiabatic passage techniques. All these features inspire the further application of MSDs on robust quantum information processing in experiment.
Two-body interactions and decay of three-level Rydberg-dressed atoms
Helmrich, S; Pehoviak, N; Whitlock, S
2015-01-01
We theoretically analyze the interactions and decay rates for atoms dressed by multiple laser fields to strongly interacting Rydberg states using a quantum master equation approach. In this framework a comparison of two-level and three-level Rydberg-dressing schemes is presented. We identify a resonant enhancement of the three-level dressed interaction strength which originates from cooperative multiphoton couplings as well as small distance dependent decay rates. In this regime the soft-core shape of the potential is independent of the sign of the bare Rydberg-Rydberg interaction, while its sign can be repulsive or attractive depending on the intermediate state detuning. As a consequence, near-resonant Rydberg dressing in three-level atomic systems may enable the realization of laser driven quantum fluids with long-range and anisotropic interactions and with controllable dissipation.
Two-body interactions and decay of three-level Rydberg-dressed atoms
Helmrich, S.; Arias, A.; Pehoviak, N.; Whitlock, S.
2016-02-01
We theoretically analyze the interactions and decay rates for atoms dressed by multiple laser fields to strongly interacting Rydberg states using a quantum master equation approach. In this framework a comparison of two-level and three-level Rydberg-dressing schemes is presented. We identify a resonant enhancement of the three-level dressed interaction strength which originates from cooperative multiphoton couplings as well as small distance dependent decay rates. In this regime the soft-core shape of the potential is independent of the sign of the bare Rydberg-Rydberg interaction, while its sign can be repulsive or attractive depending on the intermediate state detuning. As a consequence, near-resonant Rydberg dressing in three-level atomic systems may enable the realization of laser driven quantum fluids with long-range and anisotropic interactions and with controllable dissipation.
Grid Integration of Single Stage Solar PV System using Three-level Voltage Source Converter
Hussain, Ikhlaq; Kandpal, Maulik; Singh, Bhim
2016-08-01
This paper presents a single stage solar PV (photovoltaic) grid integrated power generating system using a three level voltage source converter (VSC) operating at low switching frequency of 900 Hz with robust synchronizing phase locked loop (RS-PLL) based control algorithm. To track the maximum power from solar PV array, an incremental conductance algorithm is used and this maximum power is fed to the grid via three-level VSC. The use of single stage system with three level VSC offers the advantage of low switching losses and the operation at high voltages and high power which results in enhancement of power quality in the proposed system. Simulated results validate the design and control algorithm under steady state and dynamic conditions.
Transformerless dc-Isolated Converter
Rippel, Wally E.
1987-01-01
Efficient voltage converter employs capacitive instead of transformer coupling to provide dc isolation. Offers buck/boost operation, minimal filtering, and low parts count, with possible application in photovoltaic power inverters, power supplies and battery charges. In photovoltaic inverter circuit with transformerless converter, Q2, Q3, Q4, and Q5 form line-commutated inverter. Switching losses and stresses nil because switching performed when current is zero.
A Comparative analysis of three level VSC based multi-pulse STATCOM
Directory of Open Access Journals (Sweden)
Smruti Ranjan Barik
2014-07-01
Full Text Available This paper presents a comparative analysis among different models of three level NPC (Neutral point clamped VSC (Voltage source converter based STATCOMs. Here separate models of 12- pulse, 24-pulse, 36-pulse, 48-pulse VSC based STATCOMs are configured in MATLAB environment. These individual models are synthesized using appropriate number of three level converters which are switched at fundamental frequency and their gate pulse pattern are properly phase shifted to get desired number of pulses. The simulation results of each individual model are analyzed in three different modes: inductive, capacitive and floating mode. Harmonic content of the proposed higher pulse models are limited as per IEEE 519 standards.
Dynamic Behavior of Lambda-Type Three-Level Atoms and Two-Mode Cavity Field
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A system comprising of Lambda-type three-level atoms and the two-mode cavity field is considered in this paper. Under the adiabatical approximation and the large detuning condition, the effective Hamiltonian of the system in the interaction picture can be given out. If the two identical three-level atoms pass through the cavity in turn, the entangled state atoms can be generated. When the interaction time is taken to an appropriate value, the maximally entangled states are created. At the same time, the dynamic behaviors of the system are studied in detail.
Cascaded Multicell Trans-Z-Source Inverters
DEFF Research Database (Denmark)
Li, Ding; Chiang Loh, Poh; Zhu, Miao;
2013-01-01
Inverters with high-output voltage gain usually face the problem of high-input current flowing through their components. The problem might further be exaggerated if the inverters use high-frequency magnetic devices like transformers or coupled inductors. Leakage inductances of these devices must....... Simulation and experimental results have shown that the multicell inverters can produce the same high-voltage gain, while keeping currents and voltages of the components low. The inverters can also step down their output voltages like a traditional voltage-source inverter without compromising waveform...
Multilevel Inverter by Cascading Industrial VSI
DEFF Research Database (Denmark)
Teodorescu, Remus; Blaabjerg, Frede; Pedersen, John Kim;
2002-01-01
-source inverter that uses three IGBT triphase inverter modules along with an output transformer to obtain a 3 p.u. multilevel output voltage is introduced. The system yields in high-quality multistep voltage with up to 4 levels and low dv/dt, balanced operation of the inverter modules, each supplying a third...... of the motor rated kVA. The concept of using cascaded inverters is further extended to a new modular motor-modular inverter system where the motor winding connections are reconnected into several three-phase groups, either six-lead or 12-lead connection according to the voltage level, each powered...
Advancement in solar PV Inverter
Directory of Open Access Journals (Sweden)
Devendra Doda
2012-09-01
Full Text Available This teardown article will delve into the architectural design and components of a solar inverter card starting from the Solar panel DC inputs and working through the DC to AC conversion process to the AC output that is sent out to the power grid. Features needed to be implemented into such a design to meet various safety and other performance standards as well as stringent power company demands upon the signal that is put onto their grid will be shown. In the process, major elements and component choices made in the design of the series of solar inverters, from the EMI suppression capacitors with a special emphasis on isolation and protection, through the smart use of optically isolated MOSFETgatedrivers.
Carrier-based modulation schemes for various three-level matrix converters
DEFF Research Database (Denmark)
Blaabjerg, Frede; Loh, P.C.; Rong, R.C.;
2008-01-01
Matrix converters with three-level phase switching and five-level line switching characteristics have recently been proposed as improved ldquoall semiconductorrdquo ac-ac power processors. For their control, different modulation schemes have also been developed with different researchers claiming...... be implemented on a single common hardware platform....
A three-level framework for performance-based railway timetabling
DEFF Research Database (Denmark)
Goverde, Rob M P; Bešinović, Nikola; Binder, Anne;
2016-01-01
. This paper presents a performance-based railway timetabling framework integrating timetable construction and evaluation on three levels: microscopic, macroscopic, and a corridor fine-tuning level, where each performance indicator is optimized or evaluated at the appropriate level. A modular implementation...
Radiation forces on a three-level atom in the high-order Bessel beams
Institute of Scientific and Technical Information of China (English)
Wang Zheng-Ling; Yin Jian-Ping
2008-01-01
The general expressions of the average dissipative and dipole forces acting on a A-configuration three-level atom in an arbitrary light field are derived by means of the optical Bloch equations based on the atomic density matrix elements, and the general properties of the average dissipative and dipole forces on a three-level atom in the linearly-polarized high-order Bessel beams (HBBs) are analysed. We find a resonant property (with two resonant peaks) of the dissipative force and a non-resonant property (with two pairs of non-resonant peaks) of the dipole force on the three-level atom, which are completely different from those on the two-level atom. Meanwhile we find a saturation effect of the average dissipative force in the HBB, which comes from the saturation of the upper-level population. Our study shows that the general expressions of the average dissipative and dipole forces on the three-level atom will be simplified to those of the two-level atom under the approximation of large detuning. Finally, we study the axial and azimuthal Doppler cooling of atoms in 1D optical molasses composed of two counter-propagating HBBs and discuss the azimuthal influence of the HBB on the Doppler cooling limit. We also find that the Doppler limit of atoms in the molasses HBB is slightly below the conventional Doppler limit of hг/(2кB) due to the orbital angular momentum lh of the HBB.
High-Speed Generation of Entangled States for Two Three-Level Atoms
Institute of Scientific and Technical Information of China (English)
ZHENG Shi-Biao
2007-01-01
A scheme is presented for generating entangled states for two three-level atoms in a cavity. In the scheme two atoms simultaneously interact with a cavity mode with a small detuning. Thus, the operation time is very short,which is important in view of decoherence.
Kramers-Kronig relation in a Doppler-broadenedΛ-type three-level system
Institute of Scientific and Technical Information of China (English)
王梦; 庞兆广; 王如泉; 左战春; 芦小刚; 白金海; 裴丽娅; 缪兴绪; 高艳磊; 吴令安; 傅盘铭; 杨世平
2015-01-01
We measure the absorption and dispersion in a Doppler-broadenedΛ-type three level system by resonant stimulated Raman spectroscopy with homodyne detection. Through studying the dressed state energies of the system, it is found that the absorption and dispersion satisfy the Kramers–Kronig relation. The absorption and dispersion spectra calculated by employing this relation agree well with our experimental observations.
Initiation of superfluorescence in a three-level ''swept-gain'' amplifier
International Nuclear Information System (INIS)
Initiation of superfluorescence in a medium consisting of three-level atoms is studied. Strong influence of the pump pulse evolution on the superfluorescence radiation is pointed out. The explicit formulas for the average superfluorescence intensity and the delay time are presented and their dependence on the length of the sample is discussed. (author)
International Nuclear Information System (INIS)
Voltage source inverter (VSI) can produce single and three-phase (3P) AC voltages from a constant or variable DC voltage. There are many ways to control the VSI output voltage. Each control way produces some harmonics at the VSI output voltage. The space vector pulse width modulation (SVPWM) may be more effective than other modulation methods, e.g. harmonic injection, phase shifting, multi career pulse width modulation, in decreasing the low order harmonics (LOH). Different switching strategies (SSs) of power electronic devices in SVPWM have some specific advantages and disadvantages with regard to one another. In this paper, a comparative study between different SVPWM SSs is carried out by considering some objective functions such as total harmonic distortion (THD), power and switching losses, the ratio of the harmonic components to the fundamental component, distortion factor (DF). It is also shown that by selecting an optimized and appropriate SS for SVPWM, the harmonic orders, which are the multiples of the frequency index (FI), are eliminated. Then, to investigate the impact of variations of the capacitors voltage and switching frequency on power quality criteria, the most appropriate and optimized SS is applied to a 3P three-level (3L) neutral-point-clamped (NPC) VSI to supply a 3P load. This paper also presents a novel and optimized SS and control approach for a 3L two-quadrant (2Q) chopper in NPC VSI superconducting magnetic energy storage (SMES). Using the proposed SS, the voltage of the VSI capacitors in SMES can be independently controlled; also, the minimum power and switching losses - as well as the proper convection - can be achieved using this same strategy. The simulation results indicate that when combined with a proportional-integral (PI) control approach the proposed SS can be easily implemented in the power networks and can balance and stabilize the multi-level VSIs' capacitor voltage level. The voltage variation of the capacitors in the steady
Energy Technology Data Exchange (ETDEWEB)
Mohammad Reza, Alizadeh Pahlavani [Department of Electrical Engineering, Iran University of Science and Technology (IUST), Tehran (Iran, Islamic Republic of); Ali, Mohammadpour Hossine [Department of Electrical Engineering, University of South Carolina, Columbia, SC (United States)
2010-12-15
Voltage source inverter (VSI) can produce single and three-phase (3P) AC voltages from a constant or variable DC voltage. There are many ways to control the VSI output voltage. Each control way produces some harmonics at the VSI output voltage. The space vector pulse width modulation (SVPWM) may be more effective than other modulation methods, e.g. harmonic injection, phase shifting, multi career pulse width modulation, in decreasing the low order harmonics (LOH). Different switching strategies (SSs) of power electronic devices in SVPWM have some specific advantages and disadvantages with regard to one another. In this paper, a comparative study between different SVPWM SSs is carried out by considering some objective functions such as total harmonic distortion (THD), power and switching losses, the ratio of the harmonic components to the fundamental component, distortion factor (DF). It is also shown that by selecting an optimized and appropriate SS for SVPWM, the harmonic orders, which are the multiples of the frequency index (FI), are eliminated. Then, to investigate the impact of variations of the capacitors voltage and switching frequency on power quality criteria, the most appropriate and optimized SS is applied to a 3P three-level (3L) neutral-point-clamped (NPC) VSI to supply a 3P load. This paper also presents a novel and optimized SS and control approach for a 3L two-quadrant (2Q) chopper in NPC VSI superconducting magnetic energy storage (SMES). Using the proposed SS, the voltage of the VSI capacitors in SMES can be independently controlled; also, the minimum power and switching losses - as well as the proper convection - can be achieved using this same strategy. The simulation results indicate that when combined with a proportional-integral (PI) control approach the proposed SS can be easily implemented in the power networks and can balance and stabilize the multi-level VSIs' capacitor voltage level. The voltage variation of the capacitors in the
Phase-factor-dependent symmetries and quantum phases in a three-level cavity QED system
Fan, Jingtao; Yu, Lixian; Chen, Gang; Jia, Suotang
2016-05-01
Unlike conventional two-level particles, three-level particles may support some unitary-invariant phase factors when they interact coherently with a single-mode quantized light field. To gain a better understanding of light-matter interaction, it is thus necessary to explore the phase-factor-dependent physics in such a system. In this report, we consider the collective interaction between degenerate V-type three-level particles and a single-mode quantized light field, whose different components are labeled by different phase factors. We mainly establish an important relation between the phase factors and the symmetry or symmetry-broken physics. Specifically, we find that the phase factors affect dramatically the system symmetry. When these symmetries are breaking separately, rich quantum phases emerge. Finally, we propose a possible scheme to experimentally probe the predicted physics of our model. Our work provides a way to explore phase-factor-induced nontrivial physics by introducing additional particle levels.
First direct evidence of a vertebrate three-level trophic chain in the fossil record.
Kriwet, Jürgen; Witzmann, Florian; Klug, Stefanie; Heidtke, Ulrich H J
2008-01-22
We describe the first known occurrence of a Permian shark specimen preserving two temnospondyl amphibians in its digestive tract as well as the remains of an acanthodian fish, which was ingested by one of the temnospondyls. This exceptional find provides for the first time direct evidence of a vertebrate three-level food chain in the fossil record with the simultaneous preservation of three trophic levels. Our analysis shows that small-sized Lower Permian xenacanthid sharks of the genus Triodus preyed on larval piscivorous amphibians. The recorded trophic interaction can be explained by the adaptation of certain xenacanthids to fully freshwater environments and the fact that in these same environments, large temnospondyls occupied the niche of modern crocodiles. This unique faunal association has not been documented after the Permian and Triassic. Therefore, this Palaeozoic three-level food chain provides strong and independent support for changes in aquatic trophic chain structures through time. PMID:17971323
The asymmetry of the Autler-Townes doublet in a three-level system
Institute of Scientific and Technical Information of China (English)
Zhang Lian-Shui; Feng Xiao-Min; Li Xiao-Wei; Han Li; Fu Guang-Sheng
2004-01-01
The effect of the Bloch-Siegert shift on a strongly driven transition is studied in a three-level double-resonance configuration and the result is presented in this paper. We show that when a resonantly driven transition is probed to a third level, the Bloch-Siegert shift leads to an asymmetric Autler-Townes doublet. An important conclusion is that the asymmetry depends only on the driving field intensity, in contrast to a previous study where it is reported that the asymmetry depends not only on the driving field intensity but also on the characteristics of the three-level system. Our result implies an alternative way of measuring the Bloch-Siegert shift.
Design of LCL-Filter Based Three-level Active Power Filter
Directory of Open Access Journals (Sweden)
Shilan Chen
2013-07-01
Full Text Available This paper proposes an improved design of LCL-Filters for Three-Level Shunt Active power filters (APF. Available design principles are presented to achieve high compensation bandwidth and low switching frequency current. Then, affecitons of different parameters are taken into consideration of constraints on LCL-Filter design with detail analysis of ripple current. A simple and practical design procedure of LCL-Filter for Three-Level APF is subsequently proposed. The first step is to choose the resonant frequency of LCL-Filter according to the highest order harmonic needed to be compensated. Then it is aim to optimize the parameters of the LCL-Filter based on the design principles and constraints. The simulation results verify the effectiveness of the proposed method.
Vacuum-Induced Quantum Interference in a Trapped ∧-Configuration Three-Level System
Institute of Scientific and Technical Information of China (English)
WANG Zheng-Ling; YIN Jian-Ping
2005-01-01
@@ In consideration of quantization of centre-of-mass motion, we derive the second-order solution of the dynamic equation of a ∧-configuration three-level atom confined in an approximately harmonic trap by using the timedependent perturbation theory. It is found that there are a series of dark lines in the second-order probability spectrum with multi-peak structures, which is the result of the quantum interference from the same vacuum mode in the spontaneous decay process of the trapped atom from the upper level to the two nearby lower levels. Our study shows that the second-order spectrum may be modified by the oscillation frequency Ω of the trap and the frequency difference △ between two lower levels of the three-level atom, and the depth of the dark lines from the vacuum-induced quantum interference effect is strongly dependent on the above two parameters (Ω and △).
On inverting the Koszul complex
Khuri-Makdisi, Kamal
2007-01-01
Let V be an n-dimensional vector space. We give a direct construction of an exact sequence that gives a GL(V)-equivariant "resolution" of each symmetric power S^t V in terms of direct sums of tensor products of the form \\wedge^{i_1} V \\otimes ... \\otimes \\wedge^{i_p} V. This exact sequence corresponds to inverting the relation in the representation ring of GL(V) that is described by the Koszul complex, and has appeared before in work by B. Totaro, analogously to a construction of K. Akin invo...
Multilevel Inverters for Electric Vehicle Applications
Energy Technology Data Exchange (ETDEWEB)
Habetler, T.G.; Peng, F.Z.; Tolbert, L.M.
1998-10-22
This paper presents multilevel inverters as an application for all-electric vehicle (EV) and hybrid-electric vehicle (HEV) motor drives. Diode-clamped inverters and cascaded H-bridge inverters, (1) can generate near-sinusoidal voltages with only fundamental frequency switching; (2) have almost no electromagnetic interference (EMI) and common-mode voltage; and (3) make an EV more accessible/safer and open wiring possible for most of an EV'S power system. This paper explores the benefits and discusses control schemes of the cascade inverter for use as an EV motor drive or a parallel HEV drive and the diode-clamped inverter as a series HEV motor drive. Analytical, simulated, and experimental results show the superiority of these multilevel inverters for this new niche.
Selection of Carrier Waveforms for PWM Inverter
Institute of Scientific and Technical Information of China (English)
陈国呈; 屈克庆; 许春雨; 孙承波
2003-01-01
In this paper the influence of different carrier waveforms upon the output characteristics of PWM inverter is described in detail. When a triangular carrier waveform is used in hard-switching PWM inverters, harmonics exist in the neighborhood of the output frequency of the inverter output voltage and current due to the dead time. The triangular carrier waveform used in soft-switching PWM inverter will cause difficulties in controlling resonance-trigger time, higher loss in the resonant circuit, and less utilization of the DC bus voltage. If a sawtooth carrier is used in hard-switching PWM inverter, there will be severe distortion in the current waveform. When sawtooth carriers with alternate positive and negative slopes are used in soft-switching PWM inverters, the resonancetrigger time is easy to control, and distortion in the output voltage and current caused by the dead time will not appear.
Cascaded trans-z-source inverters
DEFF Research Database (Denmark)
Li, Ding; Loh, Poh Chiang; Zhu, Miao;
2011-01-01
the compatibility for distributed sources. Unlike existing techniques, voltage stresses within the proposed inverters are better distributed among the passive components. Theoretical analysis for explaining these operating features has already been discussed before simulation were performed and an experimental......Z-source inverter is a recently proposed single-stage inverter with added voltage-boost capability for complementing the usual voltage-buck operation of a traditional voltage-source inverter. As long as the transformer element added in to the z-source concept, a trans-z-source inverter with one...... transformer and one capacitor is reported recently. This paper has adapted the cascaded concept into the trans-z-source and trans-quasi-z-source inverters to extend each to the cascaded topologies before combination is made with allowing more sources embedded which reduces the capacitor voltage and enhanced...
Enhanced Nonlinear Generation in a Three-Level Medium with Spatially Dependent Coherence
Paspalakis, E
2002-01-01
We consider a method for efficient parametric generation of a laser pulse. A single laser field is injected to a three-level medium which has two lower states and one excited state. The lower states are prepared initially in a position-dependent coherent superposition state. It is shown that by proper choice of the position dependence of the superposition along the direction of propagation, the incoming field can be converted completely to a new field.
Coordinating Three-Level Supply Chain by Revenue-Sharing Contract with Sales Effort Dependent Demand
Qinghua Pang; Yuer Chen; Yulu Hu
2014-01-01
Revenue-sharing contract is a kind of mechanism to improve performance or to achieve perfect coordination of supply chain. Considering a three-level supply chain consisting of a manufacturer, a distributor, and a retailer who faces a stochastic and sales effort dependent demand, the paper analyzes the impact of sales effort on supply chain coordination and expounds the reasons why traditional revenue-sharing contract cannot coordinate supply chain in this condition. Given three cases: only th...
Transient Emission of Three-Level Atoms in a Photonic Crystal with a Pseudogap
Institute of Scientific and Technical Information of China (English)
XU Xing-Sheng; CHEN Hong-Da
2006-01-01
@@ We study the transient behaviour of an external field induced transient emission of three-level atomic systems embedded in a photonic crystal with a pseudogap. The expressions for fluorescence spectra and emission dynamics for luminescent materials in the pseudogap are obtained. The properties of the transient gain in the pseudogap are discussed. It shows that the transient emission in the pseudogap can be effectively controlled.
First direct evidence of a vertebrate three-level trophic chain in the fossil record
Kriwet, Jürgen; Witzmann, Florian; Klug, Stefanie; Heidtke, Ulrich H.J
2007-01-01
We describe the first known occurrence of a Permian shark specimen preserving two temnospondyl amphibians in its digestive tract as well as the remains of an acanthodian fish, which was ingested by one of the temnospondyls. This exceptional find provides for the first time direct evidence of a vertebrate three-level food chain in the fossil record with the simultaneous preservation of three trophic levels. Our analysis shows that small-sized Lower Permian xenacanthid sharks of the genus Triod...
Effects of colored noise on Landau-Zener Transitions: Two and Three-Level Systems
Kenmoe, M. B.; Phien, H. N.; Kiselev, M. N.; L.C.Fai
2012-01-01
We investigate the Landau-Zener transition in two- and three- level systems subject to a classical Gaussian noise. Two complementary limits of the noise being fast and slow compared to characteristic Landau-Zener tunnel times are discussed. The analytical solution of a density matrix (Bloch) equation is given for a long time asymptotic of transition probability. It is demonstrated that the transition probability induced/assisted by the fast noise can be obtained through a procedure of {\\it Bl...
Emission spectrum of a harmonically trapped A-type three-level atom
Institute of Scientific and Technical Information of China (English)
Guo Hong; Tang Pei
2013-01-01
We theoretically investigate the emission spectrum for a ∧-type three-level atom trapped in the node of a standing wave.We show that the atomic center-of-mass motion not only directly affects the peak number,peak position,and peak height in the atomic emission spectrum,but also influences the effects of the cavity field and the atomic initial state on atomic emission spectrum.
Nonlinear Theory of Light Speed Reduction in a Three-Level A System
Institute of Scientific and Technical Information of China (English)
王德重; 李代军; 刘夏姬; 李师群; 王育竹
2001-01-01
We present a nonlinear theory of light velocity reduction in a three-level A system based on electromagneticllyinduced transparency. Analysis shows that the probe field propagates with a velocity that is quite strongly dependent on its intensity instead of being merely approximately dependent on the coupling intensity. Moreover,the minimum group velocity of the probe field is analytically given for a given input power.
Gavryusev, V; Ferreira-Cao, M; Zürn, G; Hofmann, C S; Günter, G; Schempp, H; Robert-de-Saint-Vincent, M; Whitlock, S; Weidemüller, M
2016-01-01
We present combined measurements of the spatially-resolved optical spectrum and the total excited-atom number in an ultracold gas of three-level atoms under electromagnetically induced transparency conditions involving high-lying Rydberg states. The observed optical transmission of a weak probe laser at the center of the coupling region exhibits a double peaked spectrum as a function of detuning, whilst the Rydberg atom number shows a comparatively narrow single resonance. By imaging the transmitted light onto a charge-coupled-device camera, we record hundreds of spectra in parallel, which are used to map out the spatial profile of Rabi frequencies of the coupling laser. Using all the information available we can reconstruct the full one-body density matrix of the three-level system, which provides the optical susceptibility and the Rydberg density as a function of spatial position. These results help elucidate the connection between three-level interference phenomena, including the interplay of matter and li...
Gavryusev, V.; Signoles, A.; Ferreira-Cao, M.; Zürn, G.; Hofmann, C. S.; Günter, G.; Schempp, H.; Robert-de-Saint-Vincent, M.; Whitlock, S.; Weidemüller, M.
2016-08-01
We present combined measurements of the spatially resolved optical spectrum and the total excited-atom number in an ultracold gas of three-level atoms under electromagnetically induced transparency conditions involving high-lying Rydberg states. The observed optical transmission of a weak probe laser at the center of the coupling region exhibits a double peaked spectrum as a function of detuning, while the Rydberg atom number shows a comparatively narrow single resonance. By imaging the transmitted light onto a charge-coupled-device camera, we record hundreds of spectra in parallel, which are used to map out the spatial profile of Rabi frequencies of the coupling laser. Using all the information available we can reconstruct the full one-body density matrix of the three-level system, which provides the optical susceptibility and the Rydberg density as a function of spatial position. These results help elucidate the connection between three-level interference phenomena, including the interplay of matter and light degrees of freedom and will facilitate new studies of many-body effects in optically driven Rydberg gases.
A coordination theoretic model for three level supply chains using contracts
Indian Academy of Sciences (India)
Arshinder; Arun Kanda; S G Deshmukh
2009-10-01
Typically, supply chain members are dependent on each other to manage various resources and information. The conﬂicting objectives and lack of coordination between supply chain members may often cause uncertainties in supply and demand. The basic elements of coordination theory like interdependency, coherency and mutuality may help in effective ﬂow of information and material between the dependent supply chain members. Supply chain contract can be an effective coordination mechanism to motivate all the members to be a part of the entire supply chain. There are different types of supply chain contracts such as buy back and quantity ﬂexibility contracts. Supply chain performance may be substantially improved by properly designing the contracts to share risks and rewards. The objective of this paper is to explore the applicability of coordination elements through an analytical model in three-level (Manufacturer–distributor–retailer) serial supply chains using contracts. The model evaluates the impact of supply chain contracts on various performance measures. The impact of some contract may be on some speciﬁc performance measure only, which helps managers to choose the type of contract if there is an objective of improving certain performance measure before hand. In three-level supply chains, the contracts are designed at two distinct interfaces: Manufacturer–distributor and distributor–retailer. The model demonstrates the complexity in evaluating the decision variables of three level supply chains. The proposed model is a novel approach to apply coordination theory at various levels of supply chain. The model also presents how the coordination elements are related to each other in various coordination cases.
Cooling and trapping of three-level atoms in a bichromatic standing wave
Pu, H.; Cai, T.; Bigelow, N. P.; Grove, T. T.; Gould, P. L.
1995-02-01
We show that a three-level atom in the cascade configuration can be stably trapped and cooled in one dimension by an intense bichromatic standing wave. At the two-photon resonance, rectified dipole forces result in a deep potential well which can be used to localize the atoms in space. In the vicinity of the rectified potential minimum, the spatial dependence of the dressed state energies can lead to a velocity dependence of the force which produces damping of the atomic motion. Consideration of the heating effects of momentum diffusion indicates that cooling and stable trapping at low temperatures is possible in such a bichromatic field.
Observation of three-level rectified dipole forces acting on trapped atoms
Grove, T. T.; Duncan, B. C.; Sanchez-Villicana, V.; Gould, P. L.
1995-06-01
We have observed rectified dipole forces acting on three-level atoms in the cascade configuration. Laser cooled and trapped rubidium atoms are illuminated with an intense bichromatic standing wave (780 and 776 nm) tuned near resonance with the 5S1/2-->5P3/2-->5D5/2 transitions. The resulting rectified forces produce periodic potential wells (71-μm period), which localize the cold atoms. Experimental results are in reasonable agreement with theoretical predictions. These forces may be useful in atom optics and laser traps.
THE CONSTRUCTIONS OF ALMOST BINARY SEQUENCE PAIRS WITH THREE-LEVEL CORRELATION BASED ON CYCLOTOMY
Institute of Scientific and Technical Information of China (English)
Peng Xiuping; Xu Chengqian
2012-01-01
In this paper,a new class of almost binary sequence pair with a single zero element is presented.The almost binary sequence pairs with three-level correlation are constructed based on cyclotomic numbers of order 2,4,and 6.Most of them have good correlation and balance property,whose maximum nontrivial correlation magnitudes are 2 and the difference between the numbers of occurrence of +1's and -1's are 0 or 1.In addition,the corresponding binary sequence pairs are investigated as well and we can also get some kinds of binary sequence pairs with optimum balance and good correlation.
Enhanced cooling of a V-type three-level atom in an optical cavity
Institute of Scientific and Technical Information of China (English)
Liu Li-Wei; Tan Lei; Ding Cai-Ying; Zhang Yu-Qing; Tan Wen-Ting
2008-01-01
We have studied theoretically and numerically the enhanced cooling of a V-type three-level atom in a high-finesse optical cavity and shown that the cooling rate can be increased by one order of magnitude over that of a two-level atom,and the momentum amplitude tends to a stationary state much smaller than that of a two-level atom.We have further shown that the cooling rate can be significantly improved by using feedback and a time-dependent pump.
Detecting non-Abelian geometric phases with three-level {Lambda} systems
Energy Technology Data Exchange (ETDEWEB)
Du Yanxiong; Xue Zhengyuan; Zhang Xinding; Yan Hui [Laboratory of Quantum Information Technology, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China)
2011-09-15
We show that a non-Abelian gauge potential in two nearly degenerated dressed states may be induced by two laser beams interacting with a three-level {Lambda} atomic system. We demonstrate that the populations of the atomic states at the end of a composed path formed by two closed loops are dependent on the order of those two loops, showing an unambiguous signature of the non-Abelian geometric phase. Through numerical calculations, we show that the non-Abelian feature of the geometric phases can be tested under realistic conditions.
Integrated Differential Three-Level High-Voltage Pulser Output Stage for CMUTs
DEFF Research Database (Denmark)
Llimos Muntal, Pere; Larsen, Dennis Øland; Jørgensen, Ivan Harald Holger;
2015-01-01
A new integrated differential three-level highvoltage pulser output stage to drive capacitive micromachined ultrasonic transducers (CMUTs) is proposed in this paper. A topology comparison between the new differential output stage and the most commonly used single-ended topology is performed...... in order to assess the performance of the new output stage. The new topology achieves a 10.9% lower power consumption and an area reduction of 23.5% for the same specifications. The differential output stage proposed is able to generate pulses with a slew rate of 2 V/ns, a frequency of 5MHz and voltage...
Photon statistics of radiation in an incoherently pumped three-level cascade system
Ahmed, Shaik; Singh, Suneel; Lakshmi, P Anantha
2014-01-01
We study the intensity-intensity correlations of the radiation emitted on probe transition in a three level cascade electromagnetically induced transparency (EIT) scheme. By applying an incoherent pump, we also monitor further changes in the characteristics of the emitted radiation. It is found that application of even a very weak incoherent pump can significantly alter the characteristics of the emitted radiation, even though the EIT characteristics remain unaltered. Our study demonstrates that for certain range of parameter values, the two photon correlation function in the probe transition oscillates between classical and non-classical domains.
Kramers-Kronig relation in a Doppler-broadened Λ-type three-level system
Wang, Meng; Lu, Xiao-Gang; Bai, Jin-Hai; Pei, Li-Ya; Miao, Xing-Xu; Gao, Yan-Lei; Wu, Ling-An; Fu, Pan-Ming; Yang, Shi-Ping; Pang, Zhao-Guang; Wang, Ru-Quan; Zuo, Zhan-Chun
2015-11-01
We measure the absorption and dispersion in a Doppler-broadened Λ-type three level system by resonant stimulated Raman spectroscopy with homodyne detection. Through studying the dressed state energies of the system, it is found that the absorption and dispersion satisfy the Kramers-Kronig relation. The absorption and dispersion spectra calculated by employing this relation agree well with our experimental observations. Project supported by the National Basic Research Program of China (Grant Nos. 2013CB922002 and 2010CB922904), the National Natural Science Foundation of China (Grant Nos. 11274376 and 61308011), and the Natural Science Foundation of Hebei Province, China (Grant No. A2015205161).
Emission Probability of the Cascade Three-Level-Atom Mazer with Injected Atomic Coherence
Institute of Scientific and Technical Information of China (English)
熊锦; 张智明
2002-01-01
We investigate the effects of the injected atomic coherence on the atomic emission probability of the micromaser injected with ultracold cascade three-level atoms by considering that the atoms are initially in the coherent superposition states of the two upper levels. We show that there is no interference between the transitions from the two upper levels to the lowest level. In the large atom-field-detuning case, the atomic emission probability decreases as the coherent parameter increases. In the zero atom-field-detuning case, the atomic emission probability has three sets of resonance peaks. The reason for these results has been explained.
Controlling Single-Photon Transport along an Optical Waveguide by using a Three-Level Atom
Institute of Scientific and Technical Information of China (English)
TIAN Wei; CHEN Bin; XU Wei-Dong
2012-01-01
We theoretically investigate the single-photon transport properties in an optical waveguide embedded with a V-type three-level atom (VTLA) based on symmetric and asymmetric couplings between the photon and the VTLA.Our numerical results show that the transmission spectrum of the incident photon can be well controlled by virtue of both symmetric and asymmetric coupling interactions.A multifrequency photon attenuator is realized by controlling the asymmetric coupling interactions.Furthermore,the influences of dissipation of the VTLA for the realistic physical system on single-photon transport properties are also analyzed.
Coherent Phase Control of Multiphoton Ionization in Three-Level Ladder-Type System
Institute of Scientific and Technical Information of China (English)
ZHANG Shi-An; CHEN Yu-Ting; WANG Zu-Geng; SUN Zhen-Rong
2009-01-01
We present the theoretical investigation of photoelectron spectroscopy resulting from the strong field induced multiphoton ionization in a typical three-level ladder-style system.Our theoretical results show that the photoelectron spectral structure can be alternatively steered by spectral phase modulation.This physical mechanism for strong field quantum control is explicitly exploited by the time-dependent dressed state population.It is concluded that the phase-shaped laser pulses can be used to selectively manipulate the multiphoton ionization process in complicated quantum systems.
Smart Inverters for Utility and Industry Applications
DEFF Research Database (Denmark)
Xue, Yaosuo; Guerrero, Josep M.
2015-01-01
system control and communication requirements during both normal and faulty operations. Challenges may present when multiple distributed inverters are required to collectively achieve a common goal. With Industry 4.0, it is expected that smart inverters will be highly demanded at conversion...
A truncated bivariate inverted Dirichlet distribution
Directory of Open Access Journals (Sweden)
Saralees Nadarajah
2013-05-01
Full Text Available A truncated version of the bivariate inverted dirichlet distribution is introduced. Unlike the inverted dirichlet distribution, this possesses finite moments of all orders and could therefore be a better model for certain practical situations. One such situation is discussed. The moments, maximum likelihood estimators and the Fisher information matrix for the truncated distribution are derived.
Cascaded impedance networks for NPC inverter
DEFF Research Database (Denmark)
Li, Ding; Gao, Feng; Loh, Poh Chiang;
2010-01-01
Multilevel inverters are getting more and more attracted because they have better output waveform quality and lower semiconductor voltage stress. The Z-source NPC is a kind of single stage multilevel inverter which has the ability of voltage boost. But the boost capability is relatively low when...
Circuit controls transients in SCR inverters
Moore, E. T.; Wilson, T. G.
1964-01-01
Elimination of starting difficulties in SCR inverters is accomplished by the addition of two taps of the output winding of the inverter. On starting or under transient loads, the two additional taps deliver power through diodes without requiring quenching of SCR currents in excess of normal starting load.
Nanostructured Inverted Organic Photovoltaic Cells
Thomas, Michael
Organic photovoltaic cells (OPVs)are promising devices for inexpensive power generation from sunlight. Organic semiconductors, the basic materials for OPVs, can be fabricated using a broad range of fabrication technologies from vapor deposition to solution processing. Upon light absorption, a strongly bound exciton is generated which can diffuse to a donor-acceptor heterojunction. At this interface it can be dissociated into free charge carriers which can be collected by the device electrodes. A major challenge for OPVs are short exciton diffusion lengths of up to 20 nm. Morphology engineering is required in order to harvest the exciton before it recombines and improve OPV performance. This work focuses on the study of nanostructured morphologies for use in inverted architecture OPVs. Glancing angle deposition (GLAD)is employed to fabricate nanocolumnar acceptor films. Through combining these nanostructured C60 films with a conjugated polymer donor P3CBT and a small molecule 3-Q, inverted OPVs are fabricated with the goal to analyze effect of morphology engineering on device performance. A major challenge was that C60 were found to be soluble in most commonly used organic solvents such as dichlorobenzene or chloroform. Although this challenge has limited the donor choice and therefore has limited device performance, a significant effect of morphology engineering could be observed. All GLAD structured C60 OPVs outperformed state of the art architectures such as planar films and bulk heterojunctions fabricated with the same materials. For P3CBT in particular the GLAD structured devices exhibited a twofold increase in power conversion efficiency compared with bulk heterojunctions and a fourfold increase compared with planar devices. In a further study, the acceptor materials PTCDA and C60 were co-evaporated into a single film. PTCDA is stable against non-polar organic solvents while C60 provides a high electron mobility. Nanocolumnar acceptor blended PTCDA:C60 films
Leakage current measurement in transformerless PV inverters
DEFF Research Database (Denmark)
Kerekes, Tamas; Sera, Dezso; Mathe, Laszlo
2012-01-01
Photovoltaic (PV) installations have seen a huge increase during the last couple of years. Transformerless PV inverters are gaining more share of the total inverter market, due to their high conversion efficiency, small weight and size. Nevertheless safety should have an important role in case...... of these tranformerless systems, due to the missing galvanic isolation. Leakage and fault current measurement is a key issue for these inverter topologies to be able to comply with the required safety standards. This article presents the test results of two different current measurement sensors that were suggested...... to be used in commercial PV inverters for the measurement of leakage and fault ground currents. The German VDE0126–1–1 standard gives the limit for fault and leakage ground currents and all grid connected PV inverters have to comply with these limits and disconnect from the grid in case of a fault....
Coordinating Three-Level Supply Chain by Revenue-Sharing Contract with Sales Effort Dependent Demand
Directory of Open Access Journals (Sweden)
Qinghua Pang
2014-01-01
Full Text Available Revenue-sharing contract is a kind of mechanism to improve performance or to achieve perfect coordination of supply chain. Considering a three-level supply chain consisting of a manufacturer, a distributor, and a retailer who faces a stochastic and sales effort dependent demand, the paper analyzes the impact of sales effort on supply chain coordination and expounds the reasons why traditional revenue-sharing contract cannot coordinate supply chain in this condition. Given three cases: only the retailer bears the sales effort cost, only the manufacturer bears the sales effort cost, and the retailer bears the sales effort cost with the manufacturer, the paper proposes an improved revenue-sharing contract based on quantity discount policy to coordinate the supply chain. It illustrates that improved revenue sharing contract can coordinate supply chain by implementing it in one transaction or two transactions of three-level supply chain. The model of improved revenue-sharing contract is optimized, respectively, by addition form and multiplication form with sales effort dependent demand. Formulas are given to determine the optimal contract parameters. Finally, numerical experiments are given to test the accuracy of the model of improved revenue-sharing contract.
Characterization of interface traps on MOS transistor submicronic by the three level charge pumping
Sellami, M.; Bouchemat, M.; Kahouadji, M.; Djahli, F.
2005-05-01
Because of its efficiency, its high precision and its easy use regarding to classical techniques of Si-Sio2 (C-V, DLTS, Conductanceldots), interface characterization, the charge pumping technique has seen a large evolution these years. Many improvements have been made other, derivation techniques have been developed (at three-level charge pumping, spectroscopic charge pumping ldots) This technique is particularly used for very slight geometry MOS transistors damaging, where other techniques have no utility. This damaging often leads to the creation of a fixed trapped charge in the oxide coat and active electronically defaults in the oxide Semi-conductor interface after the application of ageing constraint (ionizing radiation, injection carrier). This ageing is so pronounced when the dimensions are slight this represents the main obstacle that the microelectronics must face. In this article we simulate the three-level charge pumping technique with SPICE3F4 simulator. This simulation will permit the obtaining of spatial and energetic spread of defaults at the interface.
B-MIC: An Ultrafast Three-Level Parallel Sequence Aligner Using MIC.
Cui, Yingbo; Liao, Xiangke; Zhu, Xiaoqian; Wang, Bingqiang; Peng, Shaoliang
2016-03-01
Sequence alignment is the central process for sequence analysis, where mapping raw sequencing data to reference genome. The large amount of data generated by NGS is far beyond the process capabilities of existing alignment tools. Consequently, sequence alignment becomes the bottleneck of sequence analysis. Intensive computing power is required to address this challenge. Intel recently announced the MIC coprocessor, which can provide massive computing power. The Tianhe-2 is the world's fastest supercomputer now equipped with three MIC coprocessors each compute node. A key feature of sequence alignment is that different reads are independent. Considering this property, we proposed a MIC-oriented three-level parallelization strategy to speed up BWA, a widely used sequence alignment tool, and developed our ultrafast parallel sequence aligner: B-MIC. B-MIC contains three levels of parallelization: firstly, parallelization of data IO and reads alignment by a three-stage parallel pipeline; secondly, parallelization enabled by MIC coprocessor technology; thirdly, inter-node parallelization implemented by MPI. In this paper, we demonstrate that B-MIC outperforms BWA by a combination of those techniques using Inspur NF5280M server and the Tianhe-2 supercomputer. To the best of our knowledge, B-MIC is the first sequence alignment tool to run on Intel MIC and it can achieve more than fivefold speedup over the original BWA while maintaining the alignment precision.
DEFF Research Database (Denmark)
Choi, Uimin; Blaabjerg, Frede; Lee, Kyo-Beum
2014-01-01
To improve the efficiency of the photovoltaic (PV) system, the centralized topology using three-level inverters are widely used. In this system, PV modules are separately connected to the split DC-links. This causes a decrease of maximum power point tracking (MPPT) efficiency under the partial...
Wang, Zhiping; Cao, Dewei; Yu, Benli
2016-05-01
We present a new scheme for three-dimensional (3D) atom localization in a three-level atomic system via measuring the absorption of a weak probe field. Owing to the space-dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the probe absorption. It is found that, by properly varying the parameters of the system, the probability of finding the atom in 3D space can be almost 100%. Our scheme opens a promising way to achieve high-precision and high-efficiency 3D atom localization, which provides some potential applications in laser cooling or atom nano-lithography via atom localization. PMID:27140374
Absorption Spectra of a Three-Level Atom Embedded in a PBG Reservoir
Institute of Scientific and Technical Information of China (English)
ZHANG Ke; ZHANG Han-Zhuang
2007-01-01
We introduce the 'decay rate' terms into the density matrix equations of an atom embedded in a photonic band gap (PSG)reservoir successfully.By utilizing the master equations,the probe absorption spectra and the refractivity properties of a three-level atom in the PBG reservoir are obtained.The interaction between the atom and the PBG reservoir as well as the effects of the quantum interference on the absorption of the atom has also been taken into account.It is interesting that two different types of the anomalous dispersion relations of refractivity are exhibited in one dispersion line.The methodology used here can be applied to theoretical investigation of quantum interference effects of other atomic models embedded in a PBG reservoir.
Multiscale dynamics of open three-level quantum systems with two quasi-degenerate levels
International Nuclear Information System (INIS)
We consider a three-level quantum system interacting with a bosonic thermal reservoir. Two energy levels of the system are nearly degenerate but well separated from the third one. The system-reservoir interaction constant is larger than the energy difference of the degenerate levels, but it is smaller than the separation between the latter and the remaining level. We show that the quasi-degeneracy of energy levels leads to the existence of a manifold of quasi-stationary states, and the dynamics exhibits two characteristic time scales. On the first, shorter one, initial states approach the quasi-stationary manifold. Then, on the much longer second time scale, the final unique equilibrium is reached. (paper)
Social Influence Study in Online Networks：A Three-Level Review
Institute of Scientific and Technical Information of China (English)
李辉; 崔江涛; 马建峰
2015-01-01
Social network analysis (SNA) views social relationships in terms of network theory consisting of nodes and ties. Nodes are the individual actors within the networks; ties are the relationships between the actors. In the sequel, we will use the term node and individual interchangeably. The relationship could be friendship, communication, trust, etc. These reason is that these relationships and ties are driven by social influence, which is the most important phenomenon that distinguishes social network from other networks. In this paper, we present an overview of the representative research work in social influence study. Those studies can be classified into three levels, namely individual, community, and network levels. Throughout the study, we are able to unveil a series of research directions in future and possible applications based on the state-of-the-art study.
A high-resolution time-to-digital converter using a three-level resolution
Dehghani, Asma; Saneei, Mohsen; Mahani, Ali
2016-08-01
In this article, a three-level resolution Vernier delay line time-to-digital converter (TDC) was proposed. The proposed TDC core was based on the pseudo-differential digital architecture that made it insensitive to nMOS and pMOS transistor mismatches. It also employed a Vernier delay line (VDL) in conjunction with an asynchronous read-out circuitry. The time interval resolution was equal to the difference of delay between buffers of upper and lower chains. Then, via the extra chain included in the lower delay line, resolution was controlled and power consumption was reduced. This method led to high resolution and low power consumption. The measurement results of TDC showed a resolution of 4.5 ps, 12-bit output dynamic range, and integral nonlinearity of 1.5 least significant bits. This TDC achieved the consumption of 68.43 µW from 1.1-V supply.
Dynamics of cascade three-level system interacting with the classical and quantized ﬁeld
Indian Academy of Sciences (India)
Mihir Ranjan Nath; Surajit Sen; Gautam Gangopadhyay
2003-12-01
We study the exact solutions of the cascade three-level atom interacting with a single mode classical and quantized ﬁeld with different initial conditions ofthe atom. For the semiclassical model, it is found that if the atom is initially in the middle level, the time-dependent populations of the upper and lower levels are always equal. This dynamical symmetry exhibited by the classical ﬁeld is spoiled on quantization of the ﬁeld mode. To reveal this non-classical effect, a Euler matrix formalism is developed to solve the dressed states of the cascade Jaynes–Cummings model (JCM). Possible modiﬁcation of such an effect on the collapse and revival phenomenon is also discussed by taking the quantized ﬁeld in a coherent state.
Wang, Zhiping; Cao, Dewei; Yu, Benli
2016-05-01
We present a new scheme for three-dimensional (3D) atom localization in a three-level atomic system via measuring the absorption of a weak probe field. Owing to the space-dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the probe absorption. It is found that, by properly varying the parameters of the system, the probability of finding the atom in 3D space can be almost 100%. Our scheme opens a promising way to achieve high-precision and high-efficiency 3D atom localization, which provides some potential applications in laser cooling or atom nano-lithography via atom localization.
Laser cooling of a high-temperature oscillator by a three-level system
Lau, Hoi-Kwan; Plenio, Martin B.
2016-08-01
We study the laser cooling of a mechanical oscillator through the coupling with a dissipative three-level system. Under a background temperature beyond the Lamb-Dicke regime, we extend the standard cooling analysis by separately studying the classical motion and the quantum dynamics of the oscillator. In ladder-system cooling, the cooling rate degrades by orders of magnitude at large classical motion. This phenomenon causes a critical transition of the final temperature at a hot background. In stark contrast, electromagnetic-induced-transparency (EIT) cooling with a Λ system produces significant negative cooling rate at high motional excitation. At steady state, the oscillator could exhibit both cooling and lasing behaviors. We argue that a successful EIT cooling requires either a poor quality oscillator to suppress the lasing effect, or terminating the cooling process at a transient stage.
Statistics of scattered photons from a driven three-level emitter in 1D open space
Energy Technology Data Exchange (ETDEWEB)
Roy, Dibyendu [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Div. and Center for Nonlinear Studies; Bondyopadhaya, Nilanjan [Visva-Bharati University, Santiniketan (India). Integrated Science Education and Research Centre
2014-01-07
We derive the statistics of scattered photons from a Λ- or ladder-type three-level emitter (3LE) embedded in a 1D open waveguide. The weak probe photons in the waveguide are coupled to one of the two allowed transitions of the 3LE, and the other transition is driven by a control beam. This system shows electromagnetically induced transparency (EIT) which is accompanied with the Autler-Townes splitting (ATS) at a strong driving by the control beam, and some of these effects have been observed recently. We show that the nature of second-order coherence of the transmitted probe photons near two-photon resonance changes from bunching to antibunching to constant as strength of the control beam is ramped up from zero to a higher value where the ATS appears.
A Novel Neutral Point Voltage Control Strategy for Three-Level NPC APF Based on SVPWM
Directory of Open Access Journals (Sweden)
Yao Xiaolong
2015-01-01
Full Text Available The unbalance of the neutral point voltage is an inherent problem of three-level neutral-point-clamped (NPC Active Power Filter (APF; this paper analyzes the causes of unbalanced neutral point voltage and studies the reason of the unbalance of the neutral point voltage. A novel neutral point voltage control strategy using Space Vector Pulse Width Modulation (SVPWM is proposed. The proposed strategy is based on the traditional SVPWM, by controlling the effect time of small vector, which can change the state of the midpoint voltage fluctuation, and the neutral point voltage can be maintained balance. The influence of the vector on neutral point balance is investigated in depth. Simulation results show the neutral point voltage balancing control strategy based on SPWM is effective.
Berry phases in the three-level atoms driven by quantized light fields
Indian Academy of Sciences (India)
Mai-Lin Liang; Zong-Cheng Xu; Bing Yuan
2008-03-01
A theoretical analysis of Berry's phases is given for the three-level atoms interacting with external one-mode and two-mode quantized light fields. Three main results are obtained: (i) There is a Berry phase which vanishes in the classical limit or this Berry phase is completely induced by the field quantization; (ii) Berry's phases for the one-mode field and the two-mode field can be equal so long as the photon numbers of the two-mode field are properly chosen; (iii) In the two-mode case, Berry phases of the atom interacting with one mode is affected by the other mode even if the photon number of the other mode is zero.
Temperature limits in laser cooling of free atoms with three-level cascade transitions
Cruz, Flavio C; Magno, Wictor C
2013-01-01
We employ semiclassical theoretical analysis to study laser cooling of free atoms using three-level cascade transitions, where the upper transition is much weaker than the lower one. This represents an alternate cooling scheme, particularly useful for group II atoms. We find that temperatures below the Doppler limits associated with each of these transitions are expected. The lowest temperatures arise from a remarkable increase in damping and reduced diffusion compared to two-level cooling. They are reached at the two-photon resonance, where there is a crossing between the narrow and the partially-dark dressed states, and can be estimated simply by the usual Doppler limit considering the decay rate of the optical coherence between these states.
Spatial Four Wave Mixing, Probe Images, and Fluorescence Signals in Dressed Three-Level System
Lan, Huayan; Sun, Jia; Wu, Zhenkun; Zhang, Dan; Zhang, Yiqi; Zheng, Huaibin; Zhang, Yanpeng
2013-10-01
We investigate the spatial images of the probe, generated four wave mixing (FWM) signal and the accompanying fluorescence spectrum signal simultaneously in FWM process in a cascade three-level atomic system for the first time. We experimentally observe and theoretically investigate the three spectrum signals versus the probe field as well as the dressing field frequency detunings. Utilizing the experimental results of spectrum signals, the cross phase modulation and the relative position between the weak and strong beams, we analyze the characteristics indicated in the spatial images of probe transmission and FWM, such as focusing or defocusing, shift and splitting in detail. Such studies can be used in all-optical controlled spatial signal transmission.
Negative and positive hysteresis in double-cavity optical bistability in three-level atom
Babu, H Aswath
2010-01-01
We present novel hysteretic behaviour of a three-level ladder atomic system exhibiting double-cavity optical bistability in the mean-field limit. The two fields coupling the atomic system experience feedback via two independent, unidirectional, single mode ring cavities and exhibit cooperative phenomena, simultaneously. The system displays a range of rich dynamical features varying from normal switching to self pulsing and a period-doubling route to chaos for both the fields. We focus our attention to a new hump like feature in the bistable curve arising purely due to cavity induced inversion, which eventually leads to negative hysteresis in the bistable response. This is probably the only all-optical bistable system that exhibits positive as well as negative bistable hysteresis in different input field intensity regimes. For both the fields, the switching times, the associated critical slowing down, the self-pulsing characteristics, and the chaotic behaviour can be controlled to a fair degree, moreover, all ...
Radiation pressure and laser cooling of a three-level atom in a ladder configuration
Institute of Scientific and Technical Information of China (English)
Tan Lei; Wang Zhi-Cheng; Gu Huai-Qiang
2004-01-01
Radiation pressure and laser cooling of a moving three-level ladder-type atom in bichromatic travelling fields are considered. The dependence of the force on parameters such as detunings, Rabi frequencies and spontaneous decay rates is calculated numerically and shown graphically, and analytical expressions for the force are obtained for some special parameter values. It is shown that the radiation pressure shows Doppler-shifted resonance peaks resulting respectively from one-photon and two-photon transitions. Using the present scheme, Doppler cooling of sodium exploiting the 3 2S1/2-3 2P3/2-3 2D5/2 cascade transitions is investigated. It is found that temperatures lower than the Doppler limit can be achieved.
A new interleaved double-input three-level boost converter
DEFF Research Database (Denmark)
Chen, Jianfei; Hou, Shiying; Sun, Tao;
2016-01-01
This paper proposes a new interleaved double-input three-level Boost (DITLB) converter, which is composed of two boost converters indirectly in series. Thus, a high voltage gain, together with a low component stress and a small input current ripple due to the interleaved control scheme, is achieved....... The operating principle of the DITLB converter under the individual supplying power (ISP) and simultaneous supplying power (SSP) mode is analyzed. In addition, closed-loop control strategies composed of a voltage-current loop and a voltage-balance loop, have been researched to make the converter operate...... steadily and to alleviate the neutral-point imbalance issue. Experimental results verify correctness and feasibility of the proposed topology and control strategies....
Development of a Three-Level Risk Assessment Strategy for Nanomaterials
O'Brien, N.; Cummins, E.
The release of nanomaterials and, in particular, free nanoparticles into the environment from secondary sources such as industrial manufacturing and consumer products as well as from intentional environmental application has compelled a need for a broad and pre-emptive analysis of nanomaterial fate and transport in the environment and subsequent potential human exposure pathways. The novel and potentially reactive characteristics of nanomaterials have lead to predictions on potential undesirable ramifications of exposure to these materials on human health. The three-level risk assessment strategy presented in this work has its basis in qualitative model equations that represent the inter-relationships between the different material and process characteristics and environmental behaviors and their relationship to potential exposure scenarios. The factors that influence these behaviors are examined, and the potential application of this risk assessment strategy in a semi-quantitative model is considered.
Stimulated Raman adiabatic passage in a three-level superconducting circuit
Kumar, K. S.; Vepsäläinen, A.; Danilin, S.; Paraoanu, G. S.
2016-02-01
The adiabatic manipulation of quantum states is a powerful technique that opened up new directions in quantum engineering--enabling tests of fundamental concepts such as geometrical phases and topological transitions, and holding the promise of alternative models of quantum computation. Here we benchmark the stimulated Raman adiabatic passage for circuit quantum electrodynamics by employing the first three levels of a transmon qubit. In this ladder configuration, we demonstrate a population transfer efficiency >80% between the ground state and the second excited state using two adiabatic Gaussian-shaped control microwave pulses. By doing quantum tomography at successive moments during the Raman pulses, we investigate the transfer of the population in time domain. Furthermore, we show that this protocol can be reversed by applying a third adiabatic pulse, we study a hybrid nondiabatic-adiabatic sequence, and we present experimental results for a quasi-degenerate intermediate level.
Dressed excitonic states and quantum interference in a three-level quantum dot ladder system
Energy Technology Data Exchange (ETDEWEB)
Gerardot, B D; Brunner, D; Dalgarno, P A; Warburton, R J [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Karrai, K [Center for NanoScience and Department fuer Physik der LMU, Geschwister-Scholl-Platz 1, 80539 Munich (Germany); Badolato, A [Institute of Quantum Electronics, ETH Zurich, 8093 Zurich (Switzerland); Petroff, P M [Materials Department, University of California, Santa Barbara, CA 93106 (United States)], E-mail: b.d.gerardot@hw.ac.uk
2009-01-15
We observe dressed states and quantum interference effects in a strongly driven three-level quantum dot ladder system. The effect of a strong coupling field on one dipole transition is measured by a weak probe field on the second dipole transition using differential reflection. When the coupling energy is much larger than both the homogeneous and inhomogeneous linewidths an Autler-Townes splitting is observed. Significant differences are observed when the transitions resonant with the strong and weak fields are swapped, particularly when the coupling energy is nearly equal to the measured linewidth. This result is attributed to quantum interference: destructive or constructive interference with modest visibility is observed depending on the pump/probe geometry. The data demonstrate that coherence of both the bi-exciton and the exciton is maintained in this solid-state system, even under intense illumination, which is crucial for prospects in quantum information processing and nonlinear optical devices.
Nonperturbative Leakage Elimination Operators and Control of a Three-Level System
Jing, Jun; Wu, Lian-Ao; Byrd, Mark; You, J. Q.; Yu, Ting; Wang, Zhao-Ming
2015-05-01
Dynamical decoupling operations have been shown to reduce errors in quantum information processing. Leakage from an encoded subspace to the rest of the system space is a particularly serious problem for which leakage elimination operators (LEOs) were introduced. Here we provide an analysis of nonideal pulses, rather than the well-understood idealization or bang-bang controls. Under realistic conditions, we show that these controls will provide the same protection from errors as idealized controls. Our work indicates that the effectiveness of LEOs depends on the integral of the pulse sequence in the time domain, which has been missing because of the idealization of pulse sequences. Our results are applied to a three-level system for the nitrogen-vacancy centers under an external magnetic field and are illustrated by the fidelity dynamics of LEO sequences, ranging from regular rectangular pulses, random pulses, and even disordered (noisy) pulses.
Directory of Open Access Journals (Sweden)
Shifang Guo
2016-02-01
Full Text Available We develop a theory of original quantum mechanism for finding strong optical activity quantum optical system in three-level non-chiral nanostructures, where symmetrical incidence (the propagation of the incident light is vertical to the plane of nanostructures is considered. The theory is validated via both analytical and numerical analysis of specifically designed non-chiral coupled quantum dots models. In particular, by proper designing of the incidence, tunable terahertz wave polarized even in the opposite direction of the incidence is obtained. The effect could be explored for developing novel highly efficient terahertz polarization rotator and modulators, and may lead to the appearance of a new class of negative index terahertz nanostructures.
Directory of Open Access Journals (Sweden)
Ahmad Jaafarnehad
2015-09-01
Full Text Available The role and importance of supply chain management, has faced with many challenges and problems. Although a comprehensive model of supply chain issues, has not been explained, we have to indicate that issues such as reviewing the theoretical foundations of information systems, marketing, financial management, logistical and organizational relations have been considered by many researchers. The objective of supply chain management is to improve various activities and components to increase overall supply chain system benefits. In order to achieve the overall objectives, many contradictions may occur between the components and different levels of supply chain and the contradictions that these disorders over time, result in decreased strength and competitiveness of the supply chain. Such conflicts, like marketing costs (advertising, pricing and inventory can occur during the supply chain life cycle. A Game Theory approach with respect to property is the appropriate tool for collaboration in the supply chain. This tool is used for collaborative making in any kind of supply chain such as cooperative supply chain and non-cooperative supply chain. In the present study and assuming a lack of cooperation between different levels of a supply chain, a dynamic game with complete information has been generated. In addition identifying appropriate leaders of various levels of the supply chain is considered. Non-Cooperative dynamic game mode (Stackelberg Game, for each of the three levels of supply chain including retailers, suppliers and manufacturers are modeled. Depending on the bargaining power and its position in the market, any level of supply chain can make a leader of the following rule. In the present study, the equilibrium model to play Stackelberg game may be led by a leader or leading players and ultimately identifying and modeling the appropriate unlimited three level supply chain are determined.
Modified Embedded Switched Inductor Z Source Inverter
Directory of Open Access Journals (Sweden)
V. Saravanan
2014-05-01
Full Text Available A novel modified embedded switched inductor Z-source inverter is proposed by inserting the photovoltaic panels at various locations to improve the output voltage boosting performance. The proposed inverter have the concepts of embedded and switched inductor Z source network to have better features in terms of increased voltage boost inversion ability, continuous input current, reduced voltage stress on the switches/capacitors. Simulations are carried out by employing (120° pulse width modulation scheme. Hardware implementation of the proposed topology of rating 150 W, 60 V is made and the results are experimentally verified. Switch device power and reliability evaluation of the proposed inverter are also calculated.
Passive synchronized Q-switching between a quasi-three-level and a four-level laser
DEFF Research Database (Denmark)
Cheng, Haynes Pak Hay; Tidemand-Lichtenberg, Peter; Jensen, Ole Bjarlin;
2011-01-01
Synchronized Q-switching between quasi-three-level and four-level lasers is interesting for sum-frequency generation into the blue and ultraviolet. We report, for the first time, stable synchronized Q-switching between a quasi-three-level laser at 946 nm and a four-level laser at 1064 nm in an al...
Inverted CERN School of Computing
IT Department
2011-01-01
The 5th edition of the Inverted CERN School of Computing (iCSC, “Where students turn into teachers”) will take place next Thursday and Friday (3 and 4 of March) at CERN, Building 31 - IT Amphitheatre - Third Floor. Attendance is free and open to everyone. The programme is designed so that you can attend the lectures that interest you. This year highlights: Cloud Computing, Software Engineering, Cryptography Registration is not mandatory, but will allow you to obtain a copy of the full booklet (first registered, first served). Programme overview: Thursday 3 March 2011 10:00 - 10:15 Introduction School opening 10:15 - 11:10 Lecture 1 Virtualization: what it is, how it works – Luigi Gallerani 11:20 - 12:15 Lecture 2 Server Virtualization at work – Carlos Garcia Fernandez 14:00 - 14:55 Lecture 3 Unweaving Clouds: Principles and Practice – Belmiro Moreira 15:30 - 16:25 Lecture 4 Understanding Cryptography: From Caesar to Public-Key – Nicola...
The Benefits of SiC MOSFETs in a T-Type Inverter for Grid-Tie Applications
DEFF Research Database (Denmark)
Anthon, Alexander; Zhang, Zhe; Andersen, Michael A. E.;
2016-01-01
with SiC MOSFETs is not so clear-cut. This paper now explores this issue by presenting a detailed comparison of the use of Si and SiC devices for a three-level T-Type inverter operating in grid-tie applications. The study uses datasheet values, switching loss measurements and calibrated heat sink thermal...... semiconductor conduction losses because the output current always flows through two switching devices. In contrast, the T-Type multilevel inverter has less conduction losses because only a single outer loop switching device is required to connect the converter output to the upper and lower DC buses, albeit...... power level or the switching frequency to be significantly increased for the same device losses. Hence the use of SiC MOSFETS for T-Type inverters can be seen to be an attractive and potentially cost effective alternative, since only two switching devices per phase leg need to be upgraded....
Directory of Open Access Journals (Sweden)
Nor Faezah Alias
2013-12-01
Full Text Available Three-level Neutral Point Clamped (NPC inverter allows the configuration of switching devices to operate at high voltage and produce lower current/voltage harmonics. It is known that, DTC of induction machine which employs hysteresis controller has major drawbacks namely larger torque ripple and variable switching frequency. This paper aims to propose a suitable voltage vector selection to provide better torque regulation and lower switching frequency by employing DTC with 3-level NPC multilevel inverter. A simple switching strategy was formulated using 7-level torque hysteresis and 2-level flux hysteresis controllers to give more options in selecting an appropriate voltage vector, inherently, according the motor operation conditions. The improvements offered were verified through simulations.
Inverted aggregates of luminescent ruthenium metallosurfactants
D. Domínguez-Gutiérrez; G. de Paoli; A. Guerrero-Martinez; G. Ginocchietti; D. Ebeling; E. Eiser; L. De Cola; C.J. Elsevier
2008-01-01
Metallosurfactants and their resulting aggregates combine unique spectroscopic and reactivity properties due to space confinement. We have found the requirements to obtain the first inverted micelles with luminescent metallosurfactants. The compounds possess several long linear chains that favour th
Work Station For Inverting Solar Cells
Feder, H.; Frasch, W.
1982-01-01
Final work station along walking-beam conveyor of solar-array assembly line turns each pretabbed solar cell over, depositing it back-side-up onto landing pad, which centers cell without engaging collector surface. Solar cell arrives at inverting work station collector-side-up with two interconnect tabs attached to collector side. Cells are inverted so that second soldering operation takes place in plain view of operator. Inversion protects collector from damage when handled at later stages of assembly.
Smart Inverters for Utility and Industry Applications
Xue, Yaosuo; Josep M. Guerrero
2015-01-01
Smart inverters are emerging with increasing renewable energy and smart grid development. While the recent work reviewed mostly focuses on defining standardized control functionalities and smart grid communication protocols, we take a holistic approach in this paper and propose a holon-type smart inverter concept, which features autonomous, adaptive, cooperative and plug-and-play functions. Self-awareness is also continually driven by power electronics inherently. These features can be favora...
Development of a high power NPC inverter
International Nuclear Information System (INIS)
It has been widely reported that the Common-Mode-Current disturbs a stable operation in various accelerator complex. The reason why we have such an undesired noise current is that, in an inverter circuit, the potential of neutral point will be fluctuated between high-voltage to ground-potential during each switching modes. In the Neutral-Point-Clamped (NPC) inverters, on the other hands, the neutral point of output terminals can be always clamped to the ground-potential if we chose a proper switching algorism. So that no voltage will be applied across the neutral-point and the ground potential. This is the reason why we have initiated a development of the NPC inverter to apply it into the accelerator complex. In an inverter circuit, undesirable surge voltage will be applied during its switching period. This surge voltage exceeds the maximum rating of an IGBT in worst case. Moreover, the surge voltage will increase the switching loss in devices. It is important to reduce this surge voltage to secure a stable operation of the inverter circuit. Details of our approach to minimize the surge voltage and the operational results of a developed NPC inverter are reviewed in this article. (author)
Invertible authentication for 3D meshes
Dittmann, Jana; Benedens, Oliver
2003-06-01
Digital watermarking has become an accepted technology for enabling multimedia protection schemes. Based on the introduced media independent protocol schemes for invertible data authentication in references 2, 4 and 5 we discuss the design of a new 3D invertible labeling technique to ensure and require high data integrity. We combine digital signature schemes and digital watermarking to provide a public verifiable integrity. Furthermore the protocol steps in the other papers to ensure that the original data can only be reproduced with a secret key is adopted for 3D meshes. The goal is to show how the existing protocol can be used for 3D meshes to provide solutions for authentication watermarking. In our design concept and evaluation we see that due to the nature of 3D meshes the invertible function are different from the image and audio concepts to achieve invertibility to guaranty reversibility of the original. Therefore we introduce a concept for distortion free invertibility and a concept for adjustable minimum distortion invertibility.
Analysis of three level supply chain of inventory with deterioration for multi-items
Directory of Open Access Journals (Sweden)
Narayan Singh
2014-05-01
Full Text Available The objective of this work is to generalize the three echelon supply chain model proposed by Jaber and Goyal (2008 [Jaber, M. Y., & Goyal, S. K. (2008. Coordinating a three-level supply chain with multiple suppliers, a vendor and multiple buyers. International Journal Production Economics, 116, 95-103.] for multi-items where single item was considered in production and distribution. This paper develops the coordination amongst different parties in a three-echelon supply chain with a centralized decision process. Producer, suppliers and retailers are the parties of the supply chain where multiple suppliers deliver various types of raw materials to a producer; producer produces different types of items, multi-items, in different units of the factory and supplies the items to multiple retailers. Different deterioration rates for finished items and raw materials are also considered. The model developed of this paper guarantees that the local costs for the members either remain the same as before coordination, or decrease as a result of coordination. A numerical example along with graphical illustrations is considered and the sensitivity analysis is provided to test the feasibility of the proposed model.
Two-mode mazer injected with V-type three-level atoms
Institute of Scientific and Technical Information of China (English)
梁文青; 张智明; 谢绳武
2003-01-01
The properties of the two-mode mazer operating on V-type three-level atoms are studied. The effect of the oneatom pumping on the two modes of the cavity field in number-state is asymmetric, that is, the atom emits a photon into one mode with some probability and absorbs a photon from the other mode with some other probability. This effect makes the steady-state photon distribution and the steady-state photon statistics asymmetric for the two modes. The diagram of the probability currents for the photon distribution, given by the analysis of the master equation, reveals that there is no detailed balance solution for the master equation. The computations show that the photon statistics of one mode or both modes can be sub-Poissonian, that the two modes can have anticorrelation or correlation, that the photon statistics increases with the increase of thermal photons, and that the resonant position and strength of the photon statistics are influenced by the ratio of the two coupling strengths of the two modes. These properties are also discussed physically.
Coupling of a nano mechanical oscillator and an atomic three-level medium
Sanz-Mora, A; Wüster, S; Rost, J -M
2015-01-01
We theoretically investigate the coupling of an ultracold three-level atomic gas and a nano-mechanical mirror via classical electromagnetic radiation. The radiation pressure on the mirror is modulated by absorption of a probe light field, caused by the atoms which are electromagnetically rendered nearly transparent, allowing the gas to affect the mirror. In turn, the mirror can affect the gas as its vibrations generate opto-mechanical sidebands in the control field. We show that the sidebands cause modulations of the probe intensity at the mirror frequency, which can be enhanced near atomic resonances. Through the radiation pressure from the probe beam onto the mirror, this results in resonant driving of the mirror. Controllable by the two photon detuning, the phase relation of the driving to the mirror motion decides upon amplification or damping of mirror vibrations. This permits direct phase locking of laser amplitude modulations to the motion of a nano-mechanical element opening a perspective for cavity-f...
Spontaneous emission spectrum of a three-level atom embedded in photonic crystal
Institute of Scientific and Technical Information of China (English)
刘国强; 王健; 张汉壮
2005-01-01
The two models of three-level (one upper level and two lower levels, or two upper levels and one lower level) atom embedded in a double-band photonic crystal are adopted. The atomic transitions from the upper levels to the lower levels are assumed to be coupled by the same reservoir which are respectively the isotropic photonic band gap (PBG)modes, the anisotropic PBG modes and the free vacuum modes. The effects of the fine structure of the atomic ground state levels in the model with one upper level and two lower levels, and the quantum interferences in the model with two upper levels and one lower level on the spontaneous emission spectrum of an atom are investigated in detail. Most interestingly, it is shown that new spontaneous emission lines are produced from the fine splitting of atomic ground state levels in the isotropic PBG case. The quantum interferences induce additional narrow spontaneous lines near the transition from the empty upper level to the lower level.
Variable universe adaptive fuzzy control on the quadruple inverted pendulum
Institute of Scientific and Technical Information of China (English)
李洪兴; 苗志宏; 王家银
2002-01-01
This paper focuses on the control problem of the quadruple inverted pendulum by variable universe adaptive fuzzy control.First,the mathematical model on the quadruple inverted pendulum is described and its controllability is versified.Then,an efficient controller on the quadruple inverted pendulum is designed by using variable universe adaptive fuzzy control theory.Finally the simulation of the quadruple inverted pendulum is shown in detail.Besides,the experimental results on the hardware systems,i.e.real object systems,on a single inverted pendulum,a double inverted pendulum and a triple inverted pendulum are briefly introduced.``
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.
Analyze and Improve Lifetime in 3L-NPC Inverter from Power Cycle and Thermal Balance
DEFF Research Database (Denmark)
Chen, Quan; Chen, Zhe; Wang, Qunjing;
2014-01-01
Three-level Neutral-point-clamped (3L-NPC) topology is becoming a realistic alternative to the conventional one in high-voltage and high-power application. Studies show that the power cycling mean time to failure (MTTF) of the semiconductor bond wire in 3L-NPC inverter system may be very short...... and load voltage is applied to reduce power cycle and switching losses. And then, three-level active neutral point-clamped topology is taken into account to wake the most thermo stressed device. In order to validate the improve lifetime method in this paper, a 2MW 3L-NPC converter used in wind energy has...... under some common conditions. Firstly, this paper shows the impact of some key parameters on power electronic system lifetime according the analysis of semiconductor failure mechanism. Secondly, a switching frequency reduction method based on the position relationship between the flowing current...
Directory of Open Access Journals (Sweden)
Ivan Enrici
Full Text Available Parkinson's disease (PD is characterised by well-known motor symptoms, whereas the presence of cognitive non-motor symptoms, such as emotional disturbances, is still underestimated. One of the major problems in studying emotion deficits in PD is an atomising approach that does not take into account different levels of emotion elaboration. Our study addressed the question of whether people with PD exhibit difficulties in one or more specific dimensions of emotion processing, investigating three different levels of analyses, that is, recognition, representation, and regulation.Thirty-two consecutive medicated patients with PD and 25 healthy controls were enrolled in the study. Participants performed a three-level analysis assessment of emotional processing using quantitative standardised emotional tasks: the Ekman 60-Faces for emotion recognition, the full 36-item version of the Reading the Mind in the Eyes (RME for emotion representation, and the 20-item Toronto Alexithymia Scale (TAS-20 for emotion regulation.Regarding emotion recognition, patients obtained significantly worse scores than controls in the total score of Ekman 60-Faces but not in any other basic emotions. For emotion representation, patients obtained significantly worse scores than controls in the RME experimental score but no in the RME gender control task. Finally, on emotion regulation, PD and controls did not perform differently at TAS-20 and no specific differences were found on TAS-20 subscales. The PD impairments on emotion recognition and representation do not correlate with dopamine therapy, disease severity, or with the duration of illness. These results are independent from other cognitive processes, such as global cognitive status and executive function, or from psychiatric status, such as depression, anxiety or apathy.These results may contribute to better understanding of the emotional problems that are often seen in patients with PD and the measures used to test
Spontaneous parametric down-conversion in a three-level system
International Nuclear Information System (INIS)
We have studied the space-time entangled Stokes-anti-Stokes photons generated from a three-level system. In the presence of counterpropagating pump and control lasers, paired Stokes and anti-Stokes fields are spontaneously emitted into opposite directions. The two-photon wave packet is generally a convolution of the phase matching and the third-order nonlinear susceptibility and the feature of the joint temporal correlation is determined by either of them. When the phase matching plays a major role in determining the spectral width of biphotons, the two-photon interference exhibits as conventional type-II spontaneous parametric down-conversion (SPDC). However, if the spectral width of paired photons is determined by the third-order nonlinear susceptibility, two types of four-wave mixings (FWMs) destructively interfere and contribute to the two-photon coincidences. In such a case, the coincidence counting rate appears as a damped Rabi oscillation and exhibits the photon antibunching. The oscillation frequency is equal to the effective Rabi frequency. We have also discussed polarization-entanglement generation in a three-state case. It is found that if the phase matching is crucial in determining the properties of paired Stokes and anti-Stokes photons, the generated state is the same as the degenerate type-II SPDC. However, if the spectral width is mainly controlled by the resonant linewidths in the third-order nonlinearity, one can select one FWM to produce polarization-entangled biphotons, but paired photons from the other FWM process is nonpolarization entangled
Average Dissipative and Dipole Forces on a Three-Level Atom in a Laguerre-Gaussian Beam
Institute of Scientific and Technical Information of China (English)
WANG Zheng-Ling; YIN Jian-Ping
2005-01-01
@@ By means of the optical Bloch equations based on the atomic density matrix elements, the general expressions of the average dissipative force, dipole force and the mechanical torque acting on a A-configuration three-level atom in a linearly-polarized Laguerre-Gaussian beam (LGB) with an angular momentum of lh are derived, and the general properties of the average dissipative and dipole force on the three-level atom in the linearly-polarized LGB are analysed. We find a resonant property (with two resonant peaks) of the dissipative force and a non-resonant property (with two pairs of non-resonant peaks) of the dipole force on the three-level atom, which are completely different from those on the two-level atom. Our study also shows that all of general expressions on the three-level atom will be simplified to those on the two-level atom in the approximation of large detuning.
Performance analysis of new type grid-tied inverter-Aalborg Inverter
DEFF Research Database (Denmark)
Wu, Weimin; Wang, Zhen; Ji, Junhao;
2014-01-01
Aalborg Inverter is a grid-tied DC/AC inverter. In order to optimize the design, its power losses are analyzed in detail, combined with a description of the single-phase operating principle and the modulation strategy. A 2 kW / 220 V experimental prototype is constructed to verify the theoretical...
Qinghua Pang; Yanli Hou; Yifei Lv
2016-01-01
Considering that the market demand is stochastic and dependent on effort, this essay shows that the benchmark revenue-sharing contract could not coordinate a three-level supply chain consisting of one manufacturer, one distributor, and one retailer. By assuming that the retailer himself bears the effort cost, coordination is achieved by implementing revenue-sharing contract based on rebate and penalty policy in one transaction or two transactions of three-level supply chain, and the former is...
Song, Kyung Jin; Kim, Gyu Hyung; Choi, Byeong Yeol
2011-01-01
Background To evaluate the clinical efficacy of three-level anterior cervical arthrodesis with polyethyletherketone (PEEK) cages and plate fixation for aged and osteoporotic patients with degenerative cervical spinal disorders. Methods Twenty one patients, who had undergone three-level anterior cervical arthrodesis with a cage and plate construct for degenerative cervical spinal disorder from November 2001 to April 2007 and were followed up for at least two years, were enrolled in this study....
Institute of Scientific and Technical Information of China (English)
2011-01-01
A single phase three-level converter （shown in Fig. 1） has been widely applied in high-speed railway electrical traction drive systems. But the main technical drawback of the three-level converter is DC-link neutral point voltage drift. In order to solve this problem, it is important to understand the cause of DC-link neutral point voltage drift.
Understanding USB-C Buck-Boost battery charging%解密USB-C升压-降压电池充电
Institute of Scientific and Technical Information of China (English)
魏佳
2016-01-01
本文分析了传统PC电源架构，描述了随着可反转USB Type-CTM线缆连接器的USB-C输电的广泛应用，PC电源架构将发生较大的变化。通过探讨不同的电池充电方法，解释了USB-C升压-降压充电拓扑如何才能提供设计工程师要求的灵活性、高效率和小解决方案尺寸。
A three-level non-deterministic modeling methodology for the NVH behavior of rubber connections
Stenti, A.; Moens, D.; Sas, P.; Desmet, W.
2010-03-01
Complex built-up structures such as vehicles have a variety of joint types, such as spot-welds, bolted joints, rubber joints, etc. Rubber joints highly contribute to the nonlinear level of the structure and are a major source of uncertainties and variability. In the general framework of developing engineering tools for virtual prototyping and product refinement, the modeling of the NVH behavior of rubber joints involve the computational burden of including a detailed nonlinear model of the joint and the uncertainties and variability typical of that joint in a full-scale system model. However, in an engineering design phase the knowledge on the joint rubber material properties is typically poor, and the working conditions a rubber joint will experience are generally not known in detail. This lack of knowledge often do not justify the computational burden and the modeling effort of including detailed nonlinear models of the joint in a full-scale system model. Driven by these issues a non-deterministic numerical methodology based on a three-level modeling approach is being developed. The methodology aims at evaluating directly in the frequency domain the sensitivity of the NVH behavior of a full-scale system model to the rubber joint material properties when nonlinear visco-elastic rubber material behavior is considered. Rather than including directly in the model a representation of the rubber nonlinear visco-elastic behavior, the methodology proposes to model the material nonlinear visco-elastic behavior by using a linear visco-elastic material model defined in an interval sense, from which the scatter on the full-scale system NVH response is evaluated. Furthermore the development of a multi-level solution scheme allows to reduce the computational burden introduced by the non-deterministic approach by allowing the definition of an equivalent linear interval parametric rubber joint model, ready to be assembled in a full-scale system model at a reasonable
Weather Regimes and Preferred Transition Paths in a Three-Level Quasigeostrophic Model.
Kondrashov, D.; Ide, K.; Ghil, M.
2004-03-01
Multiple flow regimes are reexamined in a global, three-level, quasigeostrophic (QG3) model with realistic topography in spherical geometry. This QG3 model, using a T21 triangular truncation in the horizontal, has a fairly realistic climatology for Northern Hemisphere winter and exhibits multiple regimes that resemble those found in atmospheric observations. Four regimes are robust to changes in the classification method, k-means versus mixture modeling, and its parameters. These regimes correspond roughly to opposite phases of the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO), respectively.The Markov chain representation of regime transitions is refined here by finding the preferred transition paths in a three-dimensional (3D) subspace of the model's phase space. Preferred transitions occur from the positive phase of the NAO (NAO+) to that of the AO (AO+), from AO+ to NAO-, and from NAO- to NAO+, but not directly between opposite phases of the AO. The angular probability density function (PDF) of the regime exits that correspond to these preferred transitions have one or, sometimes, two fairly sharp maxima. These angular PDF maxima are, in most cases, not aligned with the line segments between regime centroids in phase space and might point to heteroclinic or homoclinic connections between unstable equilibria in the model's phase space. Preferred transitions paths are also determined for a stochastically forced Lorenz system to help explain this striking feature of the QG3 model.The episodic description of the model's low-frequency variability via the Markov chain of multiple regimes is complemented by an oscillatory description. Multichannel singular-spectrum analysis is applied to the trajectory in the same 3D subspace. Two statistically significant oscillations are found and have periods of 19 and 37 days, respectively. Both oscillations have four composites that include NAO+, AO+, and NAO-, in this order. The fourth composite occurs between
Power inverter implementing phase skipping control
Energy Technology Data Exchange (ETDEWEB)
Somani, Utsav; Amirahmadi, Ahmadreza; Jourdan, Charles; Batarseh, Issa
2016-10-18
A power inverter includes a DC/AC inverter having first, second and third phase circuitry coupled to receive power from a power source. A controller is coupled to a driver for each of the first, second and third phase circuitry (control input drivers). The controller includes an associated memory storing a phase skipping control algorithm, wherein the controller is coupled to receive updating information including a power level generated by the power source. The drivers are coupled to control inputs of the first, second and third phase circuitry, where the drivers are configured for receiving phase skipping control signals from the controller and outputting mode selection signals configured to dynamically select an operating mode for the DC/AC inverter from a Normal Control operation and a Phase Skipping Control operation which have different power injection patterns through the first, second and third phase circuitry depending upon the power level.
Radiological follow-up of inverted papilloma
Energy Technology Data Exchange (ETDEWEB)
Petit, P.; Vivarrat-Perrin, L.; Champsaur, P.; Juhan, V.; Chagnaud, C.; Vidal, V.; Gaubert, J.Y.; Bartoli, J.M.; Moulin, G. [Department of Radiology, Groupe Hospitalier de la Timone, Centre Hospitalier et Universitaire de Marseille, F-13385 Marseille Cedex 5 (France); Dessi, P.; Zanaret, M. [Department of Head and Neck Surgery, Groupe Hospitalier de la Timone, Centre Hospitalier et Universitaire de Marseille, F-13385 Marseille Cedex 5 (France)
2000-07-01
The aim of this study was to describe cross-sectional imaging features of recurrent papilloma of the nasal fossa and paranasal sinuses and to evaluate the role of MR and CT in the postoperative follow-up of this lesion. Magnetic resonance imaging and CT of ten patients who presented recurrence of inverted papilloma were reviewed and correlated to initial imaging, endoscopy, and surgical reports. Imaging patterns of recurrent inverted papilloma are identical to those of initial tumors and recurrence location is closely related to the site of the former lesion. Magnetic resonance is more efficient than CT for the diagnosis and evaluation of extensions. Magnetic resonance supplies the deficiencies of endoscopy in case of extensions to the frontal sinus or the lateral recess of the antrum, especially if mucosal hyperplasia or sinusitis is associated. Magnetic resonance imaging is the first imaging modality to perform in the follow-up after removal of inverted papilloma. (orig.)
An SCR inverter for electric vehicles
Latos, T.; Bosack, D.; Ehrlich, R.; Jahns, T.; Mezera, J.; Thimmesch, D.
1980-01-01
An inverter for an electric vehicle propulsion application has been designed and constructed to excite a polyphase induction motor from a fixed propulsion battery source. The inverter, rated at 35kW peak power, is fully regenerative and permits vehicle operation in both the forward and reverse directions. Thyristors are employed as the power switching devices arranged in a dc bus commutated topology. This paper describes the major role the controller plays in generating the motor excitation voltage and frequency to deliver performance similar to dc systems. Motoring efficiency test data for the controller are presented. It is concluded that an SCR inverter in conjunction with an ac induction motor is a viable alternative to present dc vehicle propulsion systems on the basis of performance and size criteria.
Maskless inverted pyramid texturization of silicon.
Wang, Yan; Yang, Lixia; Liu, Yaoping; Mei, Zengxia; Chen, Wei; Li, Junqiang; Liang, Huili; Kuznetsov, Andrej; Xiaolong, Du
2015-06-02
We discovered a technical solution of such outstanding importance that it can trigger new approaches in silicon wet etching processing and, in particular, photovoltaic cell manufacturing. The so called inverted pyramid arrays, outperforming conventional pyramid textures and black silicon because of their superior light-trapping and structure characteristics, can currently only be achieved using more complex techniques involving lithography, laser processing, etc. Importantly, our data demonstrate a feasibility of inverted pyramidal texturization of silicon by maskless Cu-nanoparticles assisted etching in Cu(NO3)2 / HF / H2O2 / H2O solutions and as such may have significant impacts on communities of fellow researchers and industrialists.
Decoupling Control Strategy for Single Phase SPWM Parallel Inverters
Institute of Scientific and Technical Information of China (English)
Shun-Gang Xu; Jian-Ping Xu; Tai-Qiang Cao
2009-01-01
A decoupling control strategy of inverter parallel system is proposed based on the equivalent output impedance of single phase voltage source SPWM (sinusoidal pulse width modulation) inverter. The active power and reactive power are calculated in terms of output voltage and current of the inverter, and sent to the other inverters in the parallel system via controller area network (CAN) bus. By calculating and decoupling the circumfluence of the active power and reactive power, the inverters can share load current via the regulation of the reference-signal phase and amplitude. Experimental results of an 110V/2kVA inverter parallel system show the feasibility of the decoupling control strategy.
Control of a Stand-Alone Variable Speed Wind Energy Supply System †
Mohamed M. Hamada; Mohamed A. A. Wahab; Tomonobu Senjyu; Mohamed Orabi; Mahmoud M. Hussein
2013-01-01
This paper presents a simple control strategy for the operation of a variable speed stand-alone wind turbine with a permanent magnet synchronous generator (PMSG). The PMSG is connected to a three phase resistive load through a switch mode rectifier and a voltage source inverter. Control of the generator side converter is used to achieve maximum power extraction from the available wind power. Control of the DC-DC bidirectional buck-boost converter, which is connected between batteries bank and...
Biess, J. J.; Inouye, L. Y.; Shank, J. H.
1974-01-01
A high-voltage, high-power LC series resonant inverter using SCRs has been developed for an Ion Engine Power Processor. The inverter operates within 200-400Vdc with a maximum output power of 2.5kW. The inverter control logic, the screen supply electrical and mechanical characteristics, the efficiency and losses in power components, regulation on the dual feedback principle, the SCR waveforms and the component weight are analyzed. Efficiency of 90.5% and weight density of 4.1kg/kW are obtained.
MPPT algorithm for voltage controlled PV inverters
DEFF Research Database (Denmark)
Kerekes, Tamas; Teodorescu, Remus; Liserre, Marco;
2008-01-01
This paper presents a novel concept for an MPPT that can be used in case of a voltage controlled grid connected PV inverters. In case of single-phase systems, the 100 Hz ripple in the AC power is also present on the DC side. Depending on the DC link capacitor, this power fluctuation can be used...
The Internet and the Inverted Classroom.
Lage, Maureen J.; Platt, Glenn
2000-01-01
Describes a Web site that is for an undergraduate principles of microeconomics course and a main component of "The Inverted Classroom" in which lectures take place outside of class. Explains that the Web site is divided into four sections: (1) the classroom; (2) the desk; (3) the coffee shop; and (4) the library. (CMK)
Strong Connections and Invertible Weak Entwining Structures
Institute of Scientific and Technical Information of China (English)
J.N.ALONSO (A)LVAREZ; J.M.FERN(A)NDEZ VILABOA; R.GONZ(A)LEZ RODR(I)GUEZ
2012-01-01
In this paper we obtain a criterion under which the bijectivity of the canonical morphism of a weak Galois extension associated to a weak invertible entwining structure is equivalent to the existence of a strong connection form.Also we obtain an explicit formula for a strong connection under equivariant projective conditions or under coseparability conditions.
Solar Power Station Output Inverter Control Design
Directory of Open Access Journals (Sweden)
J. Bauer
2011-04-01
Full Text Available The photovoltaic applications spreads in these days fast, therefore they also undergo great development. Because the amount of the energy obtained from the panel depends on the surrounding conditions, as intensity of the sun exposure or the temperature of the solar array, the converter must be connected to the panel output. The Solar system equipped with inverter can supply small loads like notebooks, mobile chargers etc. in the places where the supplying network is not present. Or the system can be used as a generator and it shall deliver energy to the supply network. Each type of the application has different requirements on the converter and its control algorithm. But for all of them the one thing is common – the maximal efficiency. The paper focuses on design and simulation of the low power inverter that acts as output part of the whole converter. In the paper the design of the control algorithm of the inverter for both types of inverter application – for islanding mode and for operation on the supply grid – is discussed. Attention is also paid to the design of the output filter that should reduce negative side effects of the converter on the supply network.
Inverted porphyrins and expanded porphyrins: An overview
Indian Academy of Sciences (India)
S K Pushpan; S Venkatraman; V G Anand; J Sankar; H Rath; T K Chandrashekar
2002-08-01
Porphyrins and metallopophyrins have attracted the attention of chemists for the past 100 years or more owing to their widespread involvement in biology. More recently, synthetic porphyrins and porphyrin-like macrocycles have attracted the attention of researchers due to their diverse applications as sensitizers for photodynamic therapy, MRI contrasting agents, and complexing agents for larger metal ions and also for their anion binding abilities. The number of -electrons in the porphyrin ring can be increased either by increasing the number of conjugated double bonds between the pyrrole rings or by increasing the number of heterocyclic rings. Thus, 22 sapphyrins, 26 rubyrins, 30 heptaphyrins, 34 octaphyrins and higher cyclic polypyrrole analogues containing 40, 48, 64, 80 and 96 systems have recently been reported in the literature. These macrocycles show rich structural diversity where normal and different kinds of inverted structures have been identified. In this review, an attempt has been made to collect the literature of the inverted porphyrins and expanded porphyrins reported until December 2001. Since the meso aryl expanded porphyrins have tendency to form both inverted and non-inverted structures more emphasis has been given to meso aryl expanded porphyrins.
Teleporting N-qubit unknown atomic state by utilizing the V-type three-level atom
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Realizing the teleportation of quantum state, especially the teleportation of N-qubit quantum state, is of great importance in quantum information. In this paper, Raman-interaction of the V-type degenerate three-level atom and single-mode cavity field is studied by utilizing complete quantum theory. Then a new scheme for teleporting N-qubit unknown atomic state via Raman-interaction of the V-type degenerate three-level atom with a single-mode cavity field is proposed, which is based upon the complete quantum theory mentioned above.
Teleporting N-qubit unknown atomic state by utilizing the Ⅴ-type three-level atom
Institute of Scientific and Technical Information of China (English)
ZHANG XinHua; YANG ZhiYong; XU PeiPei
2009-01-01
Realizing the teleportation of quantum state, especially the teleportation of N-qubit quantum state, is of great importance in quantum information. In this paper, Raman-interaction of the Ⅴ-type degenerate three-level atom and single-mode cavity field is studied by utilizing complete quantum theory. Then a new scheme for teleporting N-qubit unknown atomic state via Raman-interaction of the Ⅴ-type degen-erate three-level atom with a single-mode cavity field is proposed, which is based upon the complete quantum theory mentioned above.
Operating Temperatures of Open-Rack Installed Photovoltaic Inverters
Energy Technology Data Exchange (ETDEWEB)
Zhang, Z.; Wang, L.; Kurtz, Sarah; Wu, J.; Quan, P.; Sorensen, R.; Liu, S.; Bai, J. B.; Zhu, Z. W.
2016-11-01
This paper presents a model for evaluating the heat-sink and component temperatures of open-rack installed photovoltaic inverters. These temperatures can be used for predicting inverter reliability. Inverter heat-sink temperatures were measured for inverters connected to three grid-connected PV (photovoltaic) test systems in Golden, Colorado, US. A model is proposed for calculating the inverter heat-sink temperature based on the ambient temperature, the ratio of the consumed power to the rated power of the inverter, and the measured wind speed. To verify and study this model, more than one year of inverter DC/AC power, irradiance, wind speed, and heat sink temperature rise data were collected and analyzed. The model is shown to be accurate in predicting average inverter temperatures, but will require further refinement for prediction of transient temperatures.
Study on inverter fault-tolerant operation of PMSM DTC
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
This paper presents an investigation of inverter fault-tolerant operation for a permanent magnet synchronous motor (PMSM) direct torque control (DTC) system under various inverter faults. The performance of a faulty standard 6-switch inverter driven PMSM DTC system is analyzed. To avoid the loss or even disaster caused by the inverter faults, a topology-modified inverter with fault-tolerant capability is introduced, which is reconfigured as a 3-phase 4-switch inverter. The modeling of the 4-switch inverter is then analyzed and a novel DTC strategy with a unique nonlinear perpendicular flux observer and feedback compensation scheme is proposed for obtaining a continuous, disturbance-free drive system. The simulation and experimental results demonstrate that the proposed inverter fault-tolerant PMSM DTC system is able to operate stably and continuously with acceptable static and pretty good dynamic performance.
Inferring protein inverted question markprotein interaction complexes from immunoprecipitation data
J. Kutzera; H.C.J. Hoefsloot; A. Malovannaya; A.B. Smit; I. van Mechelen; A.K. Smilde
2013-01-01
BACKGROUND: Protein inverted question markprotein interactions in cells are widely explored using small inverted question markscale experiments. However, the search for protein complexes and their interactions in data from high throughput experiments such as immunoprecipitation is still a challenge.
Inverter Anti-Islanding with Advanced Grid Support in Single- and Multi-Inverter Islands
Energy Technology Data Exchange (ETDEWEB)
Hoke, Andy
2016-08-16
As PV and other DER systems are connected to the grid at increased penetration levels, island detection may become more challenging for two reasons: 1. In islands containing many DERs, active inverter-based anti-islanding methods may have more difficulty detecting islands because each individual inverter's efforts to detect the island may be interfered with by the other inverters in the island. 2. The increasing numbers of DERs are leading to new requirements that DERs ride through grid disturbances and even actively try to regulate grid voltage and frequency back towards nominal operating conditions. These new grid support requirements may directly or indirectly interfere with anti-islanding controls. This report describes a series of tests designed to examine the impacts of both grid support functions and multi-inverter islands on anti-islanding effectiveness.
C. R. Balamurugan; S. P. NATARAJAN; R. BENSRAJ
2012-01-01
This paper presents the comparison of Unipolar Inverted Sine Carrier Pulse Width Modulation (UISCPWM) techniques for the Cascaded Multi Level Inverter (CMLI). Due to switch combination redundancies, there are certain degrees of freedom to generate the multilevel AC output voltage. This paper presents the use of Control Freedom Degree (CFD) combination. The effectiveness of the pulse width modulation strategies developed using CFD are demonstrated using simulation. The results indicate that th...
Mobile Inverted Constructivism: Education of Interaction Technology in Social Media
Chai, Jia-Xiang; Fan, Kuo-Kuang
2016-01-01
The combination of social media and invert teaching is a new path to inverting interation technology education and reconstructing the curriculum of context. In this paper, based on the theory of constructivism learning, a model named Mobile Inverted Constructivism (MIC) is provided. Moreover, in view of the functional quality of social media in…
Multi-cell Trans-z-source Inverters
DEFF Research Database (Denmark)
Li, Ding; Loh, Poh Chiang; Zhu, Miao;
2011-01-01
Z-source inverter is a single-stage inverter with added voltage-boost capability for complementing the usual voltage-buck operation of a traditional voltage-source inverter. And it embedded with two capacitors and two inductors in its impedance network. As long as magnetically coupling components...
Indian Academy of Sciences (India)
JAGHOURI HAKIMEH; SARBISHAEI MOHSEN; JAVIDAN KUROSH
2016-05-01
We solve the Nakajima–Zwanzig (NZ) non-Markovian master equation to study the dynamics of different types of three-level atomic systems interacting with bosonic Lorentzian reservoirs at zero temperature. Von Neumann entropy (S) is used to show the evolution of the degree of entanglement of the subsystems. The results presented are also compared with some recently published reports.
Dong, Nianbo; Spybrook, Jessaca; Kelcey, Ben
2016-01-01
The purpose of this study is to propose a general framework for power analyses to detect the moderator effects in two- and three-level cluster randomized trials (CRTs). The study specifically aims to: (1) develop the statistical formulations for calculating statistical power, minimum detectable effect size (MDES) and its confidence interval to…
Irby, Stefan M.; Phu, Andy L.; Borda, Emily J.; Haskell, Todd R.; Steed, Nicole; Meyer, Zachary
2016-01-01
There is much agreement among chemical education researchers that expertise in chemistry depends in part on the ability to coordinate understanding of phenomena on three levels: macroscopic (observable), sub-microscopic (atoms, molecules, and ions) and symbolic (chemical equations, graphs, etc.). We hypothesize this "level-coordination…
Efficient three-wave mixing in a three-level atomic medium with an assisting microwave driven field
Institute of Scientific and Technical Information of China (English)
Li Jia-Hua; Luo Jin-Ming; Yang Wen-Xing; Zhan Zhi-Ming
2006-01-01
The potential for nonlinear conversion between two laser pulses in a three-level V-type medium with assistance of an auxiliary microwave resonant radiation is studied. The results show that microwave driven field can lead to the parametric generation of a new laser pulse with high conversion efficiency when a weak pump laser pulse is applied.
DEFF Research Database (Denmark)
Pouresmaeil, Edris; Montesinos-Miracle, Daniel; Gomis-Bellmunt, Oriol
2011-01-01
This paper presents a control strategy of multilevel converters for integration of renewable energy resources into power grid. The proposed technique provides compensation for active, reactive, and harmonic current components of grid-connected loads. A three-level H-bridge converter is proposed a...
A scheme for conditional quantum phase gate via bimodal cavity and a Λ-type three-level atom
Institute of Scientific and Technical Information of China (English)
Cai Jian-Wu; Fang Mao-Fa; Liao Xiang-Ping; Zheng Xiao-Juan
2006-01-01
We propose a scheme to implement a two-qubit conditional quantum phase gate for the intracavity field via a single three-level Λ-type atom driven by two modes in a high-Q cavity. The quantum information is encoded on the Fock states of the bimodal cavity. The gate's averaged fidelity is expected to reach 99.8%.
Institute of Scientific and Technical Information of China (English)
Jun Qian; Chengpu Liu; Shangqing Gong
2005-01-01
The effects of vacuum-induced coherence (VIC) on the properties of the absorption and gain of the probe field in an equispaced three-level ladder atomic system are investigated. It is found that lasing without inversion (LWI) is remarkably enhanced due to the effect of VIC in the case of the small incoherent pump rate.
Real-Time Estimation of Power System Frequency Using a Three-Level Discrete Fourier Transform Method
Directory of Open Access Journals (Sweden)
Soon-Ryul Nam
2014-12-01
Full Text Available This paper proposes a three-level discrete Fourier transform (DFT method to provide an accurate estimate of power system frequency in real time. The first level decomposes a power system signal into two orthogonal cosine- and sine-filtered signals. The second and third levels are used to determine the amplitude ratio of the cosine- and sine-filtered signals without encountering the zero-crossing problem and with an increase in ability to suppress harmonics and inter-harmonics. The performance of the three-level DFT method is evaluated using computer-simulated signals with harmonics and inter-harmonics. The three-level DFT method is also implemented on a digital signal processor (DSP-based hardware prototype, and its performance in the hardware implementation is evaluated using a real-time digital simulator (RTDS. The evaluation results show that the three-level DFT method can achieve real-time estimation of power system frequency with satisfactory performance.
Hardware implementation of the quadruple inverted pendulum with single motor
Institute of Scientific and Technical Information of China (English)
LI Hongxing; WANG Jiayin; FENG Yanbin; GU Yundong
2004-01-01
Inverted pendulums are always used to verify some qualities and effect of certain control theory or method. Single or double inverted pendulum control system has been extensively studied for education and research purposes. However how to control a triple inverted pendulum is a difficult problem, which just a couple of control experts can solve including us. Undoubtedly, to implement controlling of a quadruple inverted pendulum is a very difficult problem, but we first successfully accomplished it using variable universe adaptive fuzzy control method in August, 2002. In this paper, a controller for a quadruple inverted pendulum is demonstrated using the variable universe adaptive fuzzy control theory.
Electronic Document Management Using Inverted Files System
Suhartono, Derwin; Setiawan, Erwin; Irwanto, Djon
2014-03-01
The amount of documents increases so fast. Those documents exist not only in a paper based but also in an electronic based. It can be seen from the data sample taken by the SpringerLink publisher in 2010, which showed an increase in the number of digital document collections from 2003 to mid of 2010. Then, how to manage them well becomes an important need. This paper describes a new method in managing documents called as inverted files system. Related with the electronic based document, the inverted files system will closely used in term of its usage to document so that it can be searched over the Internet using the Search Engine. It can improve document search mechanism and document save mechanism.
Electronic Document Management Using Inverted Files System
Directory of Open Access Journals (Sweden)
Suhartono Derwin
2014-03-01
Full Text Available The amount of documents increases so fast. Those documents exist not only in a paper based but also in an electronic based. It can be seen from the data sample taken by the SpringerLink publisher in 2010, which showed an increase in the number of digital document collections from 2003 to mid of 2010. Then, how to manage them well becomes an important need. This paper describes a new method in managing documents called as inverted files system. Related with the electronic based document, the inverted files system will closely used in term of its usage to document so that it can be searched over the Internet using the Search Engine. It can improve document search mechanism and document save mechanism.
Micro-inverter solar panel mounting
Morris, John; Gilchrist, Phillip Charles
2016-02-02
Processes, systems, devices, and articles of manufacture are provided. Each may include adapting micro-inverters initially configured for frame-mounting to mounting on a frameless solar panel. This securement may include using an adaptive clamp or several adaptive clamps secured to a micro-inverter or its components, and using compressive forces applied directly to the solar panel to secure the adaptive clamp and the components to the solar panel. The clamps can also include compressive spacers and safeties for managing the compressive forces exerted on the solar panels. Friction zones may also be used for managing slipping between the clamp and the solar panel during or after installation. Adjustments to the clamps may be carried out through various means and by changing the physical size of the clamps themselves.
Inverter Modelling Techniques for Protection Studies
Wijnhoven, Thomas; Tant, Jeroen; Deconinck, Geert
2012-01-01
Traditional fault calculation techniques are not capable of accurately modelling the short-circuit behaviour of inverter interfaced distributed generation (IIDG). As the share of IIDG continues to rise, more accurate fault simulations are required. This paper gives an overview of fault calculation techniques described in literature. All techniques are evaluated from the viewpoint of protection studies in medium and low voltage grids with a high share of IIDG. The averaged value modelling tech...
FET commutated current-FED inverter
Rippel, Wally E. (Inventor); Edwards, Dean B. (Inventor)
1983-01-01
A shunt switch comprised of a field-effect transistor (Q.sub.1) is employed to commutate a current-fed inverter (10) using thyristors (SCR1, SCR2) or bijunction transistors (Q.sub.2, Q.sub.3) in a full bridge (1, 2, 3, 4) or half bridge (5, 6) and transformer (T.sub.1) configuration. In the case of thyristors, a tapped inverter (12) is employed to couple the inverter to a dc source to back bias the thyristors during commutation. Alternatively, a commutation power supply (20) may be employed for that purpse. Diodes (D.sub.1, D.sub.2) in series with some voltage dropping element (resistor R.sub.12 or resistors R.sub.1, R.sub.2 or Zener diodes D.sub.4, D.sub.5) are connected in parallel with the thyristors in the half bridge and transformer configuration to assure sharing the back bias voltage. A clamp circuit comprised of a winding (18) negatively coupled to the inductor and a diode (D.sub.3) return stored energy from the inductor to the power supply for efficient operation with buck or boost mode.
Synthesizing Virtual Oscillators to Control Islanded Inverters
Energy Technology Data Exchange (ETDEWEB)
Johnson, Brian B.; Sinha, Mohit; Ainsworth, Nathan G.; Dorfler, Florian; Dhople, Sairaj V.
2016-08-01
Virtual oscillator control (VOC) is a decentralized control strategy for islanded microgrids where inverters are regulated to emulate the dynamics of weakly nonlinear oscillators. Compared to droop control, which is only well defined in sinusoidal steady state, VOC is a time-domain controller that enables interconnected inverters to stabilize arbitrary initial conditions to a synchronized sinusoidal limit cycle. However, the nonlinear oscillators that are elemental to VOC cannot be designed with conventional linear-control design methods. We address this challenge by applying averaging- and perturbation-based nonlinear analysis methods to extract the sinusoidal steady-state and harmonic behavior of such oscillators. The averaged models reveal conclusive links between real- and reactive-power outputs and the terminal-voltage dynamics. Similarly, the perturbation methods aid in quantifying higher order harmonics. The resultant models are then leveraged to formulate a design procedure for VOC such that the inverter satisfies standard ac performance specifications related to voltage regulation, frequency regulation, dynamic response, and harmonic content. Experimental results for a single-phase 750 VA, 120 V laboratory prototype demonstrate the validity of the design approach. They also demonstrate that droop laws are, in fact, embedded within the equilibria of the nonlinear-oscillator dynamics. This establishes the backward compatibility of VOC in that, while acting on time-domain waveforms, it subsumes droop control in sinusoidal steady state.
Energy Technology Data Exchange (ETDEWEB)
Agamy, Mohammed; Harfman-Todorovic, Maja; Elasser, Ahmed; Essakiappan, Somasundaram
2013-03-01
Photovoltaic architectures with distributed power electronics provide many advantages in terms of energy yield as well as system level optimization. As the power level of the solar farm increases it becomes more beneficial to increase the dc collection network voltage, which requires the use of power devices with higher voltage ratings, and thus making the design of efficient, low cost, distributed power converters more challenging. In this paper a simple partial power converter topology is proposed. The topology is implemented using a three-level switching cell, which allows the use of semiconductor devices with lower voltage rating; thus improving design and performance and reducing converter cost. This makes the converters suitable for use for medium to high power applications where dc-link voltages of 600V~1kV may be needed without the need for high voltage devices. Converter operation and experimental results are presented for two partial power circuit variants using three-level switching cells.
A location-inventory model for distribution centers in a three-level supply chain under uncertainty
Ali Bozorgi-Amiri; M. Saeed Jabalameli; Sara Gharegozloo Hamedani
2013-01-01
We study a location-inventory problem in a three level supply chain network under uncertainty, which leads to risk. The (r,Q) inventory control policy is applied for this problem. Besides, uncertainty exists in different parameters such as procurement, transportation costs, supply, demand and the capacity of different facilities (due to disaster, man-made events and etc). We present a robust optimization model, which concurrently specifies: locations of distribution centers to be opened, inve...
Nonclasssical Properties in Two-Mode Fields Resonantly Interacting with a Three-Level [Ⅰ]-Type Atom
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Some noclassical properties in electromagnetic Reid are investigated for the interaction of two-modes initially taken in coherent-state representation with the three-level [Ⅰ]-type atom, such as squeezing properties and violation of the Cauchy-Schwartz inequality. The enhancement of Geld squeezing is found by selective atomic measurement. The Cauchy-Schwartz inequality is violated by the application of the classical Geld followed by detection in excited state.
Passively Mode-Locked Quasi-Three-Level Nd:LuVO4 Laser with Semiconductor Saturable Absorber Mirror
Institute of Scientific and Technical Information of China (English)
HE Kun-Na; WEI Zhi-Yi; XU Chang-Wen; LI De-Hua; ZHANG Zhi-Guo; ZHANG nuai-Jin; WANG Ji-Yang; GAO Chun-Qing
2008-01-01
@@ We demonstrate a passively cw mode-locked Nd:LuVO4 laser operating on the quasi-three-level at 916 nm with a Z-folded resonator.Using a semiconductor saturable absorber mirror (SESAM) as the passive mode-locking device, we achieve stable cw mode locking with 6.7 ps pulse duration at repetition rate of 133 MHz and 88row average output power under the pump power of 17.1 W.
Institute of Scientific and Technical Information of China (English)
Zhang Qin; Qu Guang-Hui; Tang Yuan-He; Jin Kang; Ji Wei-Li
2012-01-01
We study the light propagation properties in a V-type three-level atomic system interacting with two independent broadband squeezed baths.Using the graphic method,the dependences of the absorption and the dispersion of the system on the coupling field strength,the incoherent pumping field strength and the intensity of the squeezed vacuum are analysed. The result shows that the probe pulse propagation can be changed from subluminal to superluminal speed.
Institute of Scientific and Technical Information of China (English)
ZHANG Dengyu; TANG Shiqing; WANG Xinwen; XIE Lijun; ZHAN Xiaogui; CHEN Yinhua
2011-01-01
A simple scheme is presented for generating four-photon entangled states with interaction between a three-level atom and two bimodal cavities.In the proposed protocol,the quantum information is encoded on Fock states of the cavity fields.The detection of the atom can collapse the cavity made/wave function to the desired state.The experimental feasibility of our proposal is also discussed.
Two-step Doppler cooling of a three-level ladder system with an intermediate metastable level
Champenois, Caroline; Hagel, Gaetan; Knoop, Martina; Houssin, Marie; Zumsteg, Cedric; Vedel, Fernande; Drewsen, Michael
2007-01-01
Doppler laser cooling of a three-level ladder system using two near-resonant laser fields is analyzed in the case of the intermediate level being metastable while the upper level is short-lived. Analytical as well as numerical results for e.g. obtainable scattering rates and achievable temperatures are presented. When appropriate, comparisons with two-level single photon Doppler laser cooling is made. These results are relevant to recent experimental Doppler laser cooling investigations addre...
Institute of Scientific and Technical Information of China (English)
XU Jing-Bo; ZOU Xu-Bo; GAO Xiao-Chun; FU Jian
2004-01-01
With the help of an SU(3) dynamical algebraic structure, we find an exact solution of the Milburn equation for the system of a three-level atom in the Ξ configuration interacting with one quantized field mode with arbitrary detuning. The exact solution is then used to discuss the influence of the intrinsic decoherence on the nonclassical properties of the system, such as collapes and revivals of the atomic populations, oscillations of the photon number distribution, and squeezing of the radiation field.
Institute of Scientific and Technical Information of China (English)
HU Wen-Hui; YUAN Kai-Jun; HAN Yong-Chang; Shu Chuang-Cun; CONG Shu-Lin
2007-01-01
The Autler-Townes (AT) splitting in femtosecond photoelectron spectrum of three-level Lii molecules is theoretically investigated using time-dependent quantum wave packet method. With proper femtosecond laser pulses, three peaks of the AT splitting can be observed in the photoelectron spectrum. The AT splitting stems from rapid Rabi oscillation caused by intense ultrashort laser pluses. The effects of laser parameters on the molecular ionization dynamics are also discussed.
Compact high-power tunable three-level operation of double cladding Nd-doped fiber laser
Fu, L. B.; Ibsen, M; Richardson, D J; Nilsson, J.; Payne, D. N.; Grudinin, A. B.
2005-01-01
We present a compact high-power continuous-wave tunable neodymium-doped double cladding fiber laser operating on three-level 4F3/2 - 4I9/2 transition with a maximum output power up to 810 mW. At 926.7 nm, it has a maximum slope efficiency of 49.3% against absorbed 808-nm pump. By compressing the fiber Bragg grating, 15-nm tuning range is achieved.
Test protocols for advanced inverter interoperability functions :
Energy Technology Data Exchange (ETDEWEB)
Johnson, Jay Dean; Gonzalez, Sigifredo; Ralph, Mark E.; Ellis, Abraham; Broderick, Robert Joseph
2013-11-01
Distributed energy resources (DER) such as photovoltaic (PV) systems, when deployed in a large scale, are capable of influencing significantly the operation of power systems. Looking to the future, stakeholders are working on standards to make it possible to manage the potentially complex interactions between DER and the power system. In 2009, the Electric Power Research Institute (EPRI), Sandia National Laboratories (SNL) with the U.S. Department of Energy (DOE), and the Solar Electric Power Association (SEPA) initiated a large industry collaborative to identify and standardize definitions for a set of DER grid support functions. While the initial effort concentrated on grid-tied PV inverters and energy storage systems, the concepts have applicability to all DER. A partial product of this on-going effort is a reference definitions document (IEC TR 61850-90-7, Object models for power converters in distributed energy resources (DER) systems) that has become a basis for expansion of related International Electrotechnical Commission (IEC) standards, and is supported by US National Institute of Standards and Technology (NIST) Smart Grid Interoperability Panel (SGIP). Some industry-led organizations advancing communications protocols have also embraced this work. As standards continue to evolve, it is necessary to develop test protocols to independently verify that the inverters are properly executing the advanced functions. Interoperability is assured by establishing common definitions for the functions and a method to test compliance with operational requirements. This document describes test protocols developed by SNL to evaluate the electrical performance and operational capabilities of PV inverters and energy storage, as described in IEC TR 61850-90-7. While many of these functions are not now required by existing grid codes or may not be widely available commercially, the industry is rapidly moving in that direction. Interoperability issues are already apparent as
International Nuclear Information System (INIS)
A three-level hierarchical calcium phosphate/collagen/hydroxyapatite (CaP/Col/HAp) scaffold for bone tissue engineering was developed using biomimetic synthesis. Porous CaP ceramics were first prepared as substrate materials to mimic the porous bone structure. A second-level Col network was then composited into porous CaP ceramics by vacuum infusion. Finally, a third-level HAp layer was achieved by biomimetic mineralization. The three-level hierarchical biomimetic scaffold was characterized using scanning electron microscopy, energy-dispersive x-ray spectra, x-ray diffraction and Fourier transform infrared spectroscopy, and the mechanical properties of the scaffold were evaluated using dynamic mechanical analysis. The results show that this scaffold exhibits a similar structure and composition to natural bone tissues. Furthermore, this three-level hierarchical biomimetic scaffold showed enhanced mechanical strength compared with pure porous CaP scaffolds. The biocompatibility and osteoinductivity of the biomimetic scaffolds were evaluated using in vitro and in vivo tests. Cell culture results indicated the good biocompatibility of this biomimetic scaffold. Faster and increased bone formation was observed in these scaffolds following a six-month implantation in the dorsal muscles of rabbits, indicating that this biomimetic scaffold exhibits better osteoinductivity than common CaP scaffolds. (papers)
Directory of Open Access Journals (Sweden)
Stefan Seuring
2011-04-01
Full Text Available Supply chain management and closed-loop supply chain management (CLSCM have developed into established concepts in recent years. The related material cycles and product returns form an important part of all related processes with high potential for reducing environmental burden. The paper proposes a framework for (environmentally triggered closed-loop supply chain management, spanning three different levels: the societal or governance, the chain and the actor level. Within each level, a set of activities or processes can be identified. Taken together, the levels allow a comprehensive analysis of a closed-loop supply chain system. This is illustrated building on two case studies in the textile and apparel industry, where closed-loop supply chains have been designed to take specific apparel products back. The case studies are analyzed against all three levels and allow exemplification of related challenges and interrelations among the three levels. The three levels contribute to the further comprehension of the multiple issues having to be taken into account for successfully implementing closed-loop supply chains.
Directory of Open Access Journals (Sweden)
C. R. Balamurugan
2012-11-01
Full Text Available This paper presents the comparison of Unipolar Inverted Sine Carrier Pulse Width Modulation (UISCPWM techniques for the Cascaded Multi Level Inverter (CMLI. Due to switch combination redundancies, there are certain degrees of freedom to generate the multilevel AC output voltage. This paper presents the use of Control Freedom Degree (CFD combination. The effectiveness of the pulse width modulation strategies developed using CFD are demonstrated using simulation. The results indicate that the chosen five level inverter triggered by the developed UISC phase shift PWM and UISC variable frequency PWM strategy with sine and stepped wave references and UISC alternate phase opposition disposition PWM strategy with 60 degree reference exhibit reduced harmonics and UISC carrier overlapping PWM provides higher fundamental RMS output voltage for all three chosen references. Simulations are performed using MATLAB-SIMULINK.
DEFF Research Database (Denmark)
Choi, Ui-Min; Blaabjerg, Frede; Lee, Kyo-Beum
2015-01-01
The centralized topology with three-level inverters are widely used in photovoltaic (PV) systems due to their less installation costs and complexity. However, the common maximum power point tracking (MPPT) is a disadvantage of the centralized topology particularly under the partial shading...... and panel mismatch conditions. In this system, if PV modules are separately connected to the split capacitor voltage, the MPPT efficiency can be improved by the proposed control strategy. By the proposed method, the two capacitor voltages can be controlled asymmetrically to perform the separate MPPTs...
Design of inverters for the PHOTONERGY project
Energy Technology Data Exchange (ETDEWEB)
NONE
2003-08-01
The PHOTONERGY project (the former SolcelleInverter project) was initiated on the 1st of September 2001, with a state-of-the-art analysis, which concluded into specifications. Based on this 23 topologies were analyzed in for efficiencies. The results from this analysis was five candidates which all showed a somewhat good efficiency. These five topologies were in further investigated by means of an initial design-iteration and simulations. Two different solutions were picked up in due to their high efficiency and low cost. 1. The standard full-bridge phase shifted DC/DC converter together with a standard DC/AC inverter, 2. A modified version of the novel Shimizu topology. A patent is pending on this modified version. These two inverters are in this document developed and made ready for prototyping. This includes design and selection of reactive- and switching-components, e.g. filter- and bulk-capacitors, low- and high-frequency inductors, high frequency transformers, MOSFETs and diodes. The design of auxiliary circuits is also included, e.g. gate drivers for the MOSFETs, measuring circuits for the grid-current and -voltage, PV-module-current and voltage, protection circuits, hardware near controllers and finally a switch mode power supply. However, the design of the various controllers, except the hardware near PV-current controller for the full bridge phase shifted converter, is not documented in this report but will come later on. This includes all controllers, e.g. maximum power point tracking for the PV-module, utility grid current controller, DC-link voltage controller, phase locked loops, and detection of islanding operation. All of these control loops are to be implemented in a micro-controller. (au)
Using Inverted Indices for Accelerating LINGO Calculations
DEFF Research Database (Denmark)
Kristensen, Thomas Greve; Nielsen, Jesper; Pedersen, Christian Nørgaard Storm
2011-01-01
The ever growing size of chemical data bases calls for the development of novel methods for representing and comparing molecules. One such method called LINGO is based on fragmenting the SMILES string representation of molecules. Comparison of molecules can then be performed by calculating the...... queries. The previous best method for rapidly calculating the LINGOsim similarity matrix required specialised hardware to yield a significant speedup over existing methods. By representing LINGO multisets in the verbose representation and using inverted indices it is possible to calculate LINGOsim...
An Inverted Curriculum for CS1
DEFF Research Database (Denmark)
Caspersen, Michael Edelgaard
2003-01-01
Most introductory programming courses and textbooks are structured according to the constructs of the adopted programming language and not on the basis of those language independent concepts, principles and techniques of programming that the students should master by the end of the course. We...... present and discuss the inverted curriculum for our introductory object-oriented programming course, and our experiences from teaching this course for four years. We identify four levels for the systematic construction of programs, and the structure of our programming course is based on these four levels...
On the invertibility of elementary operators
Boudi, Nadia; Bračič, Janko
2013-01-01
Let $\\mathscr{X}$ be a complex Banach space and $\\mathcal{L}(\\mathscr{X})$ be the algebra of all bounded linear operators on $\\mathscr{X}$. For a given elementary operator $\\Phi$ of length $2$ on $\\mathcal{L}(\\mathscr{X})$, we determine necessary and sufficient conditions for the existence of a solution of the equation ${\\rm X} \\Phi=0$ in the algebra of all elementary operators on $\\mathcal{L}(\\mathscr{X})$. Our approach allows us to characterize some invertible elementary operators of length...
Review of multilevel voltage source inverter topologies and control schemes
Energy Technology Data Exchange (ETDEWEB)
Colak, Ilhami [Department of Electrical Education, Faculty of Technical Education, Gazi University, Besevler, Ankara 06500 (Turkey); Kabalci, Ersan, E-mail: kabalci@nevsehir.edu.t [Department of Technical Programs, Vocational Collage of Haci Bektas, Nevsehir University, Hacibektas, Nevsehir 50800 (Turkey); Bayindir, Ramazan [Department of Electrical Education, Faculty of Technical Education, Gazi University, Besevler, Ankara 06500 (Turkey)
2011-02-15
In this study, the most common multilevel inverter topologies and control schemes have been reviewed. Multilevel inverter topologies (MLIs) are increasingly being used in medium and high power applications due to their many advantages such as low power dissipation on power switches, low harmonic contents and low electromagnetic interference (EMI) outputs. The selected switching technique to control the inverter will also have an effective role on harmonic elimination while generating the ideal output voltage. Intensive studies have been performed on carrier-based, sinusoidal, space vector and sigma delta PWM methods in open loop control of inverters. The selection of topology and control techniques may vary according to power demands of inverter. This paper and review results constitute a useful basis for matching of inverter topology and the best control scheme according to various application areas.
Generalized SVPWM Algorithm for Two Legged Three Phase Multilevel Inverter
Directory of Open Access Journals (Sweden)
Devisree Sasi
2013-07-01
Full Text Available This paper establishes the inherent fractal structure in the space vector representation of two legged three phase multilevel inverters. The established fractal structure is utilized to propose a generalized algorithm for space vector PWM generation for two legged multilevel inverters. The voltage space vectors of higher level inverters can be generated from the voltage space vectors of equivalent 2-level inverter. The proposed algorithm can be easily extended to n-level inverters without any computational complexity and it doesn’t use any look up table for sector identification. The paper explains the proposed method for 5-level inverter and simulation results are presented for 2-level, 3-level and 5-level configurations in MATLAB/SIMULINK.
Practical Results of a Five-level Flying Capacitor Inverter
Directory of Open Access Journals (Sweden)
O. Sivkov
2010-01-01
Full Text Available This paper investigates the realization of a five-level Flying Capacitor Inverter. After a brief description of general Power Electronic Converters and an introduction to the advantages of Multilevel Inverters over conventional two-level Inverters the main focus is on the five-level Flying Capacitor Inverter. The Flying Capacitor Multilevel Inverter (FCMI is a Multilevel Inverter (MI where the capacitor voltage can be balanced using only a control strategy for any number of levels. After a general description of five-level FCMI topology, the simulation and experimental results are presented. The capacitor voltage is stabilized here with various output voltage amplitude values. The simulation and experimental results of five-level FCMI show that the voltage is stabilized on capacitors using the control strategy. A single-phase five-level FCMI model is currently being developed and constructed in the laboratory. Some of the experimental results are available.
Radeonychev, Y. V.; Erukhimova, M. A.; Kocharovskaya, O. A.; Vilaseca, R.
2004-10-01
The response of a three-level atomic system driven by a resonant coherent field acting on a transition near the photonic band-edge of a photonic band-gap material as well as the general case of a frequency-dependent reservoir is studied. The strong frequency dependence of the radiation mode spectral density on the scale of the driving field Rabi frequency is shown to lead to essential and controllable changes in the refractive index, as well as to effects of electromagnetically induced transparency and lasing without inversion. Such an effective dynamic control of the atomic response enables for applications in nonlinear optics and optical computing and communications.
Lee, Woo-Mi; An, Youn-Joo
2015-05-01
In this study, we demonstrated the three-level trophic transfer of quantum dots (QDs) within the aquatic food chain. Using bioimaging, we observed QD transfer from protozoa (Astasia longa) to zooplankton (Moina macrocopa) to fish (Danio rerio). Bioimaging is an effective tool that can improve our understanding of the delivery of nanomaterials in vivo. Measurement with an intravital multiphoton laser scanning microscope visually proved the transfer of QDs from the first to the second and the second to the third levels. As QDs may be passed from lower organisms to humans via the food chain, our findings have implications for the safety of their use. PMID:25119416
Narrowband Biphoton Generation with Four-Wave Mixing in a Far-Detuning Three-Level System
Institute of Scientific and Technical Information of China (English)
CHEN Peng; ZHOU Shu-Yu; XU Zhen; DUAN Ya-Fan; CUI Guo-Dong; HONG Tao; WANG Yu-Zhu
2011-01-01
Non-classical paired photons are generated by a four-wave mixing process in a far-detuning three-level system with cold atoms.A violation of the Cauchy-Schwartz inequality of a factor of 310 is observed.This phenomenon shows that paired photons have a non-classical correlation. The experimental results are compared with theoretical results obtained using perturbation theory.The oscillation frequencies of the two-photon intensity correlation functions are in reasonable agreement with the effective Rabi frequencies of the coupling laser.However,we find that the dephasing rates (or decay rates) observed are far larger than the theoretical values.
Directory of Open Access Journals (Sweden)
Jiraporn Janwised
2014-01-01
Full Text Available We introduce a new technique, a three-level average linear-implicit finite difference method, for solving the Rosenau-Burgers equation. A second-order accuracy on both space and time numerical solution of the Rosenau-Burgers equation is obtained using a five-point stencil. We prove the existence and uniqueness of the numerical solution. Moreover, the convergence and stability of the numerical solution are also shown. The numerical results show that our method improves the accuracy of the solution significantly.
Jiraporn Janwised; Ben Wongsaijai; Thanasak Mouktonglang; Kanyuta Poochinapan
2014-01-01
We introduce a new technique, a three-level average linear-implicit finite difference method, for solving the Rosenau-Burgers equation. A second-order accuracy on both space and time numerical solution of the Rosenau-Burgers equation is obtained using a five-point stencil. We prove the existence and uniqueness of the numerical solution. Moreover, the convergence and stability of the numerical solution are also shown. The numerical results show that our method improves the accuracy of the solu...
José Luis Moletta; Ivanor Nunes Prado; Carlos Alberto Fugita; Carlos Emanuel Eiras; Camila Barbosa Carvalho; Daniel Perotto
2014-01-01
The objective of this experiment was to evaluate quantitative and qualitative characters of carcass and meat from bulls and steers finished in feedlot during a 116 day period, in individual stalls and fed with a diet of corn silage and three levels of concentrate (0.70; 0.97 and 1.23% of body weight). The concentrate was formulated with 25% soybean meal, 73% of ground corn grain 1% of a mineral mix and 1% of limestone. A total of 169 composite Purunã animals, being 94 bulls and 75 steers with...
Medium Voltage Three-level Converters for the Grid Connection of aMulti-MW Wind Turbine
DEFF Research Database (Denmark)
Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig;
2009-01-01
Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter...... connection circuit (without capacitive switching ripple filters), the 3L-HB-VSC is expected to be superior with respect to power density and reliability over the 3L-NPC- and -FC-VSCs....
Medium voltage three-level converters for the grid connection of a multi-MW wind turbine
DEFF Research Database (Denmark)
Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig;
2009-01-01
Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter...... connection circuit (without capacitive switching ripple filters), the 3L-HB-VSC is expected to be superior with respect to power density and reliability over the 3L-NPC- and -FC-VSCs....
A diode-pumped Nd3+-doped gadolinium gallium garnet quasi-three-level laser at 933 nm
Liu, J. H.; Han, Y. H.; Zhao, Y. D.
2013-11-01
We report for the first time a Nd3+-doped gadolinium gallium garnet (Nd:GGG) laser operating on a quasi-three-level laser at 933 nm, based on the 4F3/2-4I9/2 transition. Continuous wave 691 mW output power at 933 nm is obtained under 10.2 W of incident pump power. Moreover, intracavity second-harmonic generation has also been achieved with a blue power of 89 mW by using a LiB3O5 (LBO) nonlinear crystal.
Institute of Scientific and Technical Information of China (English)
Zhu Ai-Dong; Zhang Shou
2004-01-01
The dynamical property of a cascade three-level atom is investigated in the condition of atomic motion. The influence of atomic motion on the population and dipole squeezing is discussed. The results show that atomic motion makes the amplitude of atomic population be steady and increasing the parameter ep which denotes the atomic motion and the structure of field mode can shorten the period of collapse-revivals. By choosing an appropriate paramenter ep, we can obtain a dipole squeezed atom of long standing.
Hawaiian Electric Advanced Inverter Test Plan - Result Summary
Energy Technology Data Exchange (ETDEWEB)
Hoke, Anderson; Nelson, Austin; Prabakar, Kumaraguru; Nagarajan, Adarsh
2016-10-14
This presentation is intended to share the results of lab testing of five PV inverters with the Hawaiian Electric Companies and other stakeholders and interested parties. The tests included baseline testing of advanced inverter grid support functions, as well as distribution circuit-level tests to examine the impact of the PV inverters on simulated distribution feeders using power hardware-in-the-loop (PHIL) techniques. hardware-in-the-loop (PHIL) techniques.
Soft Switching SEPP High Frequency Inverter for Induction Heating
Ogiwara, Hiroyuki; Nakaoka, Mutsuo
This paper presents a novel circuit topology to attain soft switching operation of a high frequency inverter. Its output power is regulated over a wide range using a PWM control technique by connecting an auxiliary resonant circuit to the conventional single ended push pull (SEPP) high frequency inverter for induction heating. All switching devices in the proposed inverter are operated soft switching mode. This paper describes its circuit constitution and obtained experimental results from a practical point of view.
Photovoltaic Inverter Controllers Seeking AC Optimal Power Flow Solutions
Dall'Anese, Emiliano; Dhople, Sairaj V.; Giannakis, Georgios B.
2014-01-01
This paper considers future distribution networks featuring inverter-interfaced photovoltaic (PV) systems, and addresses the synthesis of feedback controllers that seek real- and reactive-power inverter setpoints corresponding to AC optimal power flow (OPF) solutions. The objective is to bridge the temporal gap between long-term system optimization and real-time inverter control, and enable seamless PV-owner participation without compromising system efficiency and stability. The design of the...
Design of a Broadband Inverted Conical Quadrifilar Helix Antenna
Jingyan Mo; Wei Liu; Weidong Fang; Haigao Xue; Zhongchao Lin
2016-01-01
This paper introduces the design of a broadband inverted conical circularly polarized quadrifilar helix antenna (QHA). The antenna has many good characteristics, including wide beam and broad bandwidth, which are achieved by utilizing inverted conical geometry and adjusting the dimensions of the inverted conical support. The antenna is fed by a wideband network to provide 90° phase difference between the four arms with constant amplitude. The antenna impedance and axial ratio bandwidth values...
Linear Maps Preserving Invertibility or Related Spectral Properties
Institute of Scientific and Technical Information of China (English)
Jin Chuan HOU; Peter SEMRL
2003-01-01
We survey some recent results on linear maps on operator algebras that preserve invert-ibility. We also consider related problems such as the problem of the characterization of linear mapspreserving spectrum, various parts of spectrum, spectral radius, quasinilpotents, etc. We present someresults on elementary operators and additive operators preserving invertibility or related properties. Inparticular, we give a negative answer to a problem posed by Gao and Hou on characterizing spectrum-preserving elementary operators. Several open problems are also mentioned.
Finishing report for the 'SolcelleInverter' project
Energy Technology Data Exchange (ETDEWEB)
Boekhoej Kjaer, S.
2005-03-01
The main objective for this research project was to develop an inverter for the AC module, where one PV module is equipped with its own dedicated inverter, and connected to the grid. A topology, among many different candidates, has been selected, based on analysis's. The inverter has been optimized in respect to cost, reliability, and efficiency, and a prototype has been build. (au)
Robustness analysis of the efficiency in PV inverters
DEFF Research Database (Denmark)
Pigazo, Alberto; Liserre, Marco; Blaabjerg, Frede;
2013-01-01
During last years an increasing attention has been paid to the efficiency of grid-connected PV inverters. They are manufactured from a number of discrete components and by using a certain topology and control strategy. Hence, the performance of a certain PV inverter not only depends on the selected...... provides a better understanding of the PV inverter performance and, in this sense, the definition of the European Efficiency must be reviewed in order to show the quality of the manufactured product....
Integral inverter/battery charger for use in electric vehicles
Thimmesch, D.
1983-01-01
The design and test results of a thyristor based inverter/charger are discussed. A battery charger is included integral to the inverter by using a subset of the inverter power circuit components. The resulting charger provides electrical isolation between the vehicle propulsion battery and ac line and is capable of charging a 25 kWh propulsion battery in 8 hours from a 220 volt ac line. The integral charger employs the inverter commutation components at a resonant ac/dc isolated converter rated at 3.6 kW. Charger efficiency and power factor at an output power of 3.6 kW are 86% and 95% respectively. The inverter, when operated with a matching polyphase ac induction motor and nominal 132 volt propulsion battery, can provide a peak shaft power of 34 kW (45 ph) during motoring operation and 45 kW (60 hp) during regeneration. Thyristors are employed for the inverter power switching devices and are arranged in an input-commutated topology. This configuration requires only two thyristors to commutate the six main inverter thyristors. Inverter efficiency during motoring operation at motor shaft speeds above 450 rad/sec (4300 rpm) is 92-94% for output power levels above 11 KW (15 hp). The combined ac inverter/charger package weighs 47 kg (103 lbs).
Multilayer control for inverters in parallel operation without signal interconnection
DEFF Research Database (Denmark)
Hua, Ming; Hu, Haibing; Xing, Yan;
2011-01-01
by adjusting the phase and amplitude of the output voltage respectively. The second layer is to compensate the droop voltage caused by the droop control and thus improve the load regulation performance of the inverter. The third layer limits the phase deviation between the inverter and the shared ac bus......A multilayer control is proposed for inverters with wireless parallel operation in this paper. The control is embedded in every inverter respectively and consists of three layers. The first layer is based on an improved droop method, which shares the active and reactive power in each module...
Advanced DC/AC inverters applications in renewable energy
Luo, Fang Lin
2013-01-01
DC/AC inversion technology is of vital importance for industrial applications, including electrical vehicles and renewable energy systems, which require a large number of inverters. In recent years, inversion technology has developed rapidly, with new topologies improving the power factor and increasing power efficiency. Proposing many novel approaches, Advanced DC/AC Inverters: Applications in Renewable Energy describes advanced DC/AC inverters that can be used for renewable energy systems. The book introduces more than 100 topologies of advanced inverters originally developed by the authors,
Inverting dedevelopment: geometric singularity theory in embryology
Bookstein, Fred L.; Smith, Bradley R.
2000-10-01
The diffeomorphism model so useful in the biomathematics of normal morphological variability and disease is inappropriate for applications in embryogenesis, where whole coordinate patches are created out of single points. For this application we need a suitable algebra for the creation of something from nothing in a carefully organized geometry: a formalism for parameterizing discrete nondifferentiabilities of invertible functions on Rk, k $GTR 1. One easy way to begin is via the inverse of the development map - call it the dedevelopment map, the deformation backwards in time. Extrapolated, this map will inevitably have singularities at which its derivative is zero. When the dedevelopment map is inverted to face forward in time, the singularities become appropriately isolated infinities of derivative. We have recently introduced growth visualizations via extrapolations to the isolated singularities at which only one directional derivative is zero. Maps inverse to these create new coordinate patches directionally rather than radically. The most generic singularity that suits this purpose is the crease f(x,y) equals (x,x2y+y3), which has already been applied in morphometrics for the description of focal morphogenetic phenomena. We apply it to embryogenesis in the form of its analytic inverse, and demonstrate its power using a priceless new data set of mouse embryos imaged in 3D by micro-MR with voxels smaller than 100micrometers 3.
Towards high performance inverted polymer solar cells
Gong, Xiong
2013-03-01
Bulk heterojunction polymer solar cells that can be fabricated by solution processing techniques are under intense investigation in both academic institutions and industrial companies because of their potential to enable mass production of flexible and cost-effective alternative to silicon-based electronics. Despite the envisioned advantages and recent technology advances, so far the performance of polymer solar cells is still inferior to inorganic counterparts in terms of the efficiency and stability. There are many factors limiting the performance of polymer solar cells. Among them, the optical and electronic properties of materials in the active layer, device architecture and elimination of PEDOT:PSS are the most determining factors in the overall performance of polymer solar cells. In this presentation, I will present how we approach high performance of polymer solar cells. For example, by developing novel materials, fabrication polymer photovoltaic cells with an inverted device structure and elimination of PEDOT:PSS, we were able to observe over 8.4% power conversion efficiency from inverted polymer solar cells.
Directory of Open Access Journals (Sweden)
Qinghua Pang
2016-01-01
Full Text Available Considering that the market demand is stochastic and dependent on effort, this essay shows that the benchmark revenue-sharing contract could not coordinate a three-level supply chain consisting of one manufacturer, one distributor, and one retailer. By assuming that the retailer himself bears the effort cost, coordination is achieved by implementing revenue-sharing contract based on rebate and penalty policy in one transaction or two transactions of three-level supply chain, and the former is a special case of the latter. When the disruptions induce the changes of the market demand, the revenue-sharing contract could not coordinate the supply chain. To deal with the problem, this essay introduces two forms of improved revenue-sharing contracts which have antidisruption ability. The model of improved revenue-sharing contract is optimized when the market demand is in the additive form with effort dependent demand. Formulas are given to calculate the optimal contract parameters. Finally, this essay demonstrates the accuracy of the model of improved revenue-sharing contract with the help of numerical examples.
A SVPWM Control Algorism for Three-level Inverter and Its Simulation%三电平逆变器空间电压矢量控制算法仿真研究
Institute of Scientific and Technical Information of China (English)
陈亚爱; 李政学; 李正熙; 周京华
2007-01-01
分析了三电平空间电压矢量调制基本原理,给出了一种采用最近三矢量法合成参考矢量的空间矢量脉宽调制( Space Vector Pulse Width Modulation , SVPWM )算法及小三角形区域判断规则、合成参考电压矢量的相应输出电压矢量作用顺序和开关信号的产生方法,探讨了影响三电平逆变器中点电压平衡的主要因素,并推导出各合成电压矢量的作用时间.仿真结果验证了本算法的有效性.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Objective: The functional relationship between calculated alpha band spectral power and inter-/intra-hemispheric coherence during a three-level working memory task of patients with mild cognitive impairment (MCI) was investigated. Methods:Subjects included 35 MCI patients according to the DSM-Ⅳ criteria (mean age: 62.3, SD: 6.5) and 34 healthy controls (mean age:57.4, SD: 4.0) were selected from the community at large. All subjects performed a simple calculation and recall task with three levels of working memory load while electroencephalograph (EEG) signal was recorded. The spectral EEG power was computed over alphal (8.0～10.0 Hz) and alpha2 (10.5～13.0 Hz) frequency bands and was compared between rest stage and working memory processing stage by two-way ANOVA. Post hoc testing analyzed the differences between each two levels of working memory load during task processing. The inter-hemisphere EEG coherence of frontal (F3-F4), central (C3-C4), parietal (P3-P4), temporal (T5-T6) as well as occipital (O1-O2) was compared between MCI patients and normal controls. The EEG signals from F3-C3,F4-C4, C3-P3, C4-P4, P3-O1, P4-O2, T5-C3, T6-C4, T5-P3 and T6-P4 electrode pairs resulted from the intra-hemispheric action for alphal and alpha2 frequency bands. Result: There was significantly higher EEG power from MCI patients than from normal controls both at rest and during working memory processing. Significant differences existed between rest condition and three-level working memory tasks (P＜0.001). The inter- and intra-hemispheric coherence during working memory tasks showed a "drop to rise" tendency compared to that at rest condition. There was significantly higher coherence in MCI patients than in the controls.When task difficulties increased, the cortical connectivity of intra-hemispheric diminished while the inter-hemispheric connectivity dominantly maintained the cognitive processing in MCI patients. Conclusion: The results of the present study indicate that the
Institute of Scientific and Technical Information of China (English)
付光杰; 王圣慧; 陈舒; 王建任; 顾宝龙
2012-01-01
The direct rotor magnetic field oriented vector control system of Aysnchronous motor is very complex,and the flux feedback signal is not easy to obtain. So this article presents a three-level slip frequency control method with high control precision, control method is simple, high static and dynamic performance characteristics based on slip frequency control method, This method does not need complex coordinate transformation and flux detection. By application of MATLAB/Simulink software to build a simulation model, in the simulation a large number of parameters through the process of debugging and optimization of the ratio adjustment, this system can eliminate the steady-state error and the ability to quickly reduce the deviation. The simulation results show, the three-level inverter slip frequency control system has good control performance.%异步电动机的直接转子磁场定向矢量控制系统极其复杂,而且磁链反馈信号不易获取,鉴于此提出了一种 基于三电平转差频率控制的方法,该方法无需进行复杂的坐标变换和磁通检测,具有控制精度高、控制方法简单、较高的动静态性能等特点.应用MATLAB/Simulink软件搭建了系统的仿真模型,在仿真实验过程中通过大量的参数调试和配比的优化调节,本系统能够消除稳态误差并能够快速减小偏差.仿真结果证明了,三电平转差频率变频调速系统具有良好的控制性能.
Three-phase inverter for small high speed motors
Mccormick, John A.; Valenzuela, Javier A.
1991-01-01
A high-frequency three-phase inverter is being developed to drive a miniature centrifugal compressor which is a key component in a long-life space-borne cryocooler. The inverter is a unique transformer-coupled design, tailored to the low-voltage high-current characteristic of the compressor's induction motor. The design and performance demonstration of a breadboard model of the inverter are described. The cryocooler uses a reverse-Brayton cycle with turbomachines to provide 5 watt of cooling at 70 K. The design target for input power to the compressor motor is 175 watts. Line-to-neutral phase voltage waveforms to be supplied by the inverter have an amplitude of 15 volt-rms at a frequency of 8 kHz. DC power at 28 volt is supplied to the inverter. The breadboard inverter was tested with a preliminary development model of the compressor. It drove the compressor over a range of operating conditions encompassing frequencies of 5 to 9 kHz at powers of 56 to 437 watt. Inverter efficiencies, calculated from experimentally verified loss models, ranged from 89 to 95 percent over the tests. The design target on efficiency is 90 percent. The inverter was demonstrated to supply starting current adequate to overcome the starting friction of the compressor's self-acting gas bearings by a safe margin.
Three-phase inverter for small high speed motors
McCormick, John A.; Valenzuela, Javier A.
1991-07-01
A high-frequency three-phase inverter is being developed to drive a miniature centrifugal compressor which is a key component in a long-life space-borne cryocooler. The inverter is a unique transformer-coupled design, tailored to the low-voltage high-current characteristic of the compressor's induction motor. The design and performance demonstration of a breadboard model of the inverter are described. The cryocooler uses a reverse-Brayton cycle with turbomachines to provide 5 watt of cooling at 70 K. The design target for input power to the compressor motor is 175 watts. Line-to-neutral phase voltage waveforms to be supplied by the inverter have an amplitude of 15 volt-rms at a frequency of 8 kHz. DC power at 28 volt is supplied to the inverter. The breadboard inverter was tested with a preliminary development model of the compressor. It drove the compressor over a range of operating conditions encompassing frequencies of 5 to 9 kHz at powers of 56 to 437 watt. Inverter efficiencies, calculated from experimentally verified loss models, ranged from 89 to 95 percent over the tests. The design target on efficiency is 90 percent. The inverter was demonstrated to supply starting current adequate to overcome the starting friction of the compressor's self-acting gas bearings by a safe margin.
Three Phase Soft Commutation Auxilary Resonant Pole Inverter
Directory of Open Access Journals (Sweden)
Vaclav Sladecek
2006-01-01
Full Text Available This paper covers the circuit modification of the power part of the inverter with auxiliary resonant poles utilising configuration of switches realised with routinely produced IGBT modules. Covered is also the control optimisation which goal is the minimisation of switching of the auxiliary resonant pole. Presented results were gained on a prototype of an inverter laboratory sample.
Entropy squeezing of the field interacting with a nearly degenerate V-type three-level atom
Institute of Scientific and Technical Information of China (English)
Zhou Qing-Chun; Zhu Shi-Ning
2005-01-01
The position- and momentum-entopic squeezing properties of the optical field in the system of a nearly degenerate three-level atom interacting with a single-mode field are investigated. Calculation results indicate that when the field is initially in the vacuum state, it may lead to squeezing of the position entropy or the momentum entropy of the field if the atom is prepared properly. The effects of initial atomic state and the splitting of the excited levels of the atom on field entropies are discussed in this case. When the initial field is in a coherent state, we find that position-entropy squeezing of the field is present even if the atom is prepared in the ground state. By comparing the variance squeezing and entropy squeezing of the field we confirm that entropy is more sensitive than variance in measuring quantum fluctuations.
Tunable continuous-wave laser at quasi-three-level with a disordered Nd:LGS crystal.
Wang, Qing; Wei, Zhiyi; Zhang, Yongdong; Zhang, Zhiguo; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang; Gao, Mingwei; Gao, Chunqing; Wang, Zhenlin
2011-05-15
A diode-pumped tunable CW Nd(3+):LGS laser at quasi-three-level has been demonstrated. The output power up to 403 mW at the central wavelength of 904 nm was obtained, corresponding to a slope efficiency of 29.7%. Taking advantage of the broad emission spectrum of the disordered crystal Nd:LGS, we tuned the laser wavelength within the spectral range of 899.8 to 906.6 nm with an etalon inserted into the V-type cavity. To the best of our knowledge, it is the first time to obtain a tunable laser based on the (4)F(3/2)-(4)I(9/2) transition of Nd(3+)-doped crystals.
Control of improved full-bridge three-level DC/DC converter for wind turbines in a DC grid
DEFF Research Database (Denmark)
Deng, Fujin; Chen, Zhe
2013-01-01
This paper presents an improved full-bridge three-level (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency...... transformer in the IFBTL dc/dc converter. A modulation strategy, including two operation modes, is proposed for the IFBTL dc/dc converter. Then, a voltage balancing control strategy is proposed for the IFBTL dc/dc converter. Furthermore, the control of the wind turbine based on the IFBTL dc/dc converter...... in a dc-grid system is presented. Finally, a small-scale IFBTL dc/dc converter prototype was built and tested in the laboratory, and the results verify the theoretical analysis....
Fang, Yao-Lung L.; Baranger, Harold U.
2016-08-01
We study photon correlations generated by scattering from three-level systems (3LS) in one dimension. The two systems studied are a 3LS in a semi-infinite waveguide (3LS plus a mirror) and two 3LS in an infinite waveguide (double 3LS). Our two-photon scattering approach naturally connects photon correlation effects with inelastically scattered photons; it corresponds to input-output theory in the weak-probe limit. At the resonance where electromagnetically induced transparency (EIT) occurs, we find that no photons are scattered inelastically and hence there are no induced correlations. Slightly away from EIT, the total inelastically scattered flux is large, being substantially enhanced due to the additional interference paths. This enhancement carries over to the two-photon correlation function, which exhibits non-classical behavior such as strong bunching with a very long time-scale. The long time scale originates from the slow-light effect associated with EIT.
Phase Control of Group Velocity in a Doppler-Broadened Λ-Type Three-Level System
Qiu, Tian-Hui; Xie, Min
2016-06-01
We theoretically investigate the phase control role on the group velocity of a weak probe field in a Doppler-broadened Λ-type three-level atomic system with the spontaneously generated coherence effect enhanced by an incoherence pump. We find that the absorption-dispersion of the probe field behaves phase and Doppler broadening-dependent phenomena, and testify that the quite large group index can be realized. The group velocity of the probe field can be switched from subluminal to superluminal or vice versa by modulating the relative phase of the two applied light fields. In contrast to the counterpropagating setting, the copropagating case is more suitable for the purpose considered in this paper due to the effectiveness of Doppler-free.
Borgohain, Nitu; Konar, S.
2016-06-01
The paper presents a theoretical study of the modulation instability of a continuous or quasi-continuous optical probe in a three level quantum well system under electromagnetically induced transparency. The modulation instability is affected by the control field detuning, as well as even-order dispersion and by the strength of Kerr (third-order) and quintic (fifth-order) nonlinearities. The fourth-order dispersion reduces the bandwidth over which modulation instability occurs, whereas the quintic nonlinearity saturates the growth of the modulation instability. Detuning the control field from resonance can significantly reduce the growth of the modulation instability at both low and high power levels. At low powers, the system becomes stable against modulation instability for small detuning of the control field and at high powers modulation instability disappears for larger detuning.
Institute of Scientific and Technical Information of China (English)
Sun Yan-Fen; Tan Lei; Xu Yan
2013-01-01
We study the features of electromagnetically induced transparency (Err) in a single ∧-type three-level atom placed in a high-finesse cavity under the action of a coupling laser and a probe laser.Our calculations show that three transparency windows appear when the pump strength is large enough.This can be explained by the residual pump in the cavity mostly resulting in energy splitting.The level ｜3> is split into four slightly different energy levels,and interference takes place between the excitation pathways.Furthermore,it is also shown that the frequencies of the EIT windows can be tuned by changing the coupling field detuning △2,and that the reflection profile is very sensitive to the cavity field detuning △c.
Institute of Scientific and Technical Information of China (English)
Liu Ji-Cai; Wang Chun-Xin; Gel'mukhanov Faris; Wang Chuan-Kui
2008-01-01
This paper investigates the dynamics of cooperative emissions in a cascade three-level system driven by an ultrashort laser pulse by solving numerically the full-wave Maxwell-Bloeh equations.The 4,4'-bis(dimethylamino) stilbene molecule is used as the model molecule because of its strong two-photon absorption property.The two-colour cooperative emissions are studied as functions of molecular number density and dephasing rate of the dipole coherence.The propagation effects on the evolution of the cooperative radiations are also taken into account.The cooperative radiations are enhanced for large number density of the molecule,while the fast dephasing of the dipole coherence reduces the intensity of the cooperative radiations and delays the emission times or even inhibits the formation of the emissions.The delay time of the radiation decreases with the increase of the molecular number density and the propagation distance.
Phase-controlled atom-photon entanglement in a three-level ∧-type closed-loop atomic system
Institute of Scientific and Technical Information of China (English)
Ali Mortezapour; Zeinab Kordi; Mohammad Mahmoudi
2013-01-01
We study the entanglement of dressed atom and its spontaneous emission in a three-level A-type closed-loop atomic system in a multi-photon resonance condition and beyond it.It is shown that the von Neumann entropy in such a system is phase-dependent,and it can be controlled by either the intensity or relative phase of applied fields.It is demonstrated that for the special case of the Rabi frequency of applied fields,the system is disentangled.In addition,we take into account the effect of Doppler broadening on the entanglement and it is found that a suitable choice of laser propagation direction allows us to obtain the steady state degree of entanglement (DEM) even in the presence of the Doppler effect.
International Nuclear Information System (INIS)
Fractional time derivative, an abstract mathematical operator of fractional calculus, is used to describe the real optical system of a V-type three-level atom embedded in a photonic crystal. A fractional kinetic equation governing the dynamics of the spontaneous emission from this optical system is obtained as a fractional Langevin equation. Solving this fractional kinetic equation by fractional calculus leads to the analytical solutions expressed in terms of fractional exponential functions. The accuracy of the obtained solutions is verified through reducing the system into the special cases whose results are consistent with the experimental observation. With accurate physical results and avoiding the complex integration for solving this optical system, we propose fractional calculus with fractional time derivative as a better mathematical method to study spontaneous emission dynamics from the optical system with non-Markovian dynamics.
Fang, Yao-Lung L
2016-01-01
We study photon correlations generated by scattering from three-level systems (3LS) in one dimension. The two systems studied are a 3LS in a semi-infinite waveguide (3LS plus a mirror) and two 3LS in an infinite waveguide (double 3LS). Our scattering approach naturally connects photon correlation effects with inelastically scattered photons; it corresponds to input-output theory in the weak-probe limit. At the resonance where electromagnetically induced transparency (EIT) occurs, we find that no photons are scattered inelastically and hence there are no induced correlations. Slightly away from EIT, the total inelastically scattered flux is large, being substantially enhanced due to the additional interference paths. This enhancement carries over to the two-photon correlation function, which exhibits non-classical behavior such as strong bunching with a very long time-scale. The long time scale originates from the slow-light effect associated with EIT.
Linear control of the flywheel inverted pendulum.
Olivares, Manuel; Albertos, Pedro
2014-09-01
The flywheel inverted pendulum is an underactuated mechanical system with a nonlinear model but admitting a linear approximation around the unstable equilibrium point in the upper position. Although underactuated systems usually require nonlinear controllers, the easy tuning and understanding of linear controllers make them more attractive for designers and final users. In a recent paper, a simple PID controller was proposed by the authors, leading to an internally unstable controlled plant. To achieve global stability, two options are developed here: first by introducing an internal stabilizing controller and second by replacing the PID controller by an observer-based state feedback control. Simulation and experimental results show the effectiveness of the design. PMID:24480638
Motion Analysis Based on Invertible Rapid Transform
Directory of Open Access Journals (Sweden)
J. Turan
1999-06-01
Full Text Available This paper presents the results of a study on the use of invertible rapid transform (IRT for the motion estimation in a sequence of images. Motion estimation algorithms based on the analysis of the matrix of states (produced in the IRT calculation are described. The new method was used experimentally to estimate crowd and traffic motion from the image data sequences captured at railway stations and at high ways in large cities. The motion vectors may be used to devise a polar plot (showing velocity magnitude and direction for moving objects where the dominant motion tendency can be seen. The experimental results of comparison of the new motion estimation methods with other well known block matching methods (full search, 2D-log, method based on conventional (cross correlation (CC function or phase correlation (PC function for application of crowd motion estimation are also presented.
Subintegrality, invertible modules and Laurent polynomial extensions
Indian Academy of Sciences (India)
Vivek Sadhu
2015-05-01
Let ⊆ be a commutative ring extension. Let $\\mathcal{I}$(, ) be the multiplicative group of invertible -submodules of . In this article, we extend a result of Sadhu and Singh by finding a necessary and sufficient condition on an integral birational extension ⊆ of integral domains with dim ≤ 1, so that the natural map $\\mathcal{I}$(, ) $→$ $\\mathcal{I}(A[X,X^{-1}],B[X,X^{-1}])$ is an isomorphism. In the same situation, we show that if dim ≥ 2, then the condition is necessary but not sufficient. We also discuss some properties of the cokernel of the natural map $\\mathcal{I}(A,B)→ \\mathcal{I}[X,X^{-1}], B[X,X^{-1}])$ in the general case.
Invertible Program Restructurings for Continuing Modular Maintenance
Cohen, Julien; Ajouli, Akram
2012-01-01
When one chooses a main axis of structural decompostion for a software, such as function- or data-oriented decompositions, the other axes become secondary, which can be harmful when one of these secondary axes becomes of main importance. This is called the tyranny of the dominant decomposition. In the context of modular extension, this problem is known as the Expression Problem and has found many solutions, but few solutions have been proposed in a larger context of modular maintenance. We solve the tyranny of the dominant decomposition in maintenance with invertible program transformations. We illustrate this on the typical Expression Problem example. We also report our experiments with Java and Haskell programs and discuss the open problems with our approach.
Alkaline degradation of invert sugar from molasses.
Yang, Byung Y; Montgomery, Rex
2007-11-01
Sugar beet and sugar cane molasses have been shown to be suitable starting materials for producing de-icer preparations. The sucrose in the molasses is hydrolyzed to glucose and fructose by invertase. The reducing sugars are then degraded by NaOH, the alkali being neutralized by the sugar acids produced, resulting in an increase of the ionic strength and consequently depression of the freezing point of the resulting solution. For the preparation of de-icers, the desired freezing point depression to a temperature of less than about -20 degrees C can be achieved by adjusting the amount and concentration of the alkali metal hydroxide used. The resulting products are biodegradable and eliminate the corrosive effects associated with the use of conventional chloride salts. Degradation of invert sugar by NaOH has been achieved without an external heat source. The reaction products showed the same freezing point depression as seen in the degradation products from pure glucose. PMID:17222551
On Invertible Sampling and Adaptive Security
DEFF Research Database (Denmark)
Ishai, Yuval; Kumarasubramanian, Abishek; Orlandi, Claudio;
2011-01-01
Secure multiparty computation (MPC) is one of the most general and well studied problems in cryptography. We focus on MPC protocols that are required to be secure even when the adversary can adaptively corrupt parties during the protocol, and under the assumption that honest parties cannot reliably...... erase their secrets prior to corruption. Previous feasibility results for adaptively secure MPC in this setting applied either to deterministic functionalities or to randomized functionalities which satisfy a certain technical requirement. The question whether adaptive security is possible for all...... functionalities was left open. We provide the first convincing evidence that the answer to this question is negative, namely that some (randomized) functionalities cannot be realized with adaptive security. We obtain this result by studying the following related invertible sampling problem: given an efficient...
Highly efficient fully transparent inverted OLEDs
Meyer, J.; Winkler, T.; Hamwi, S.; Schmale, S.; Kröger, M.; Görrn, P.; Johannes, H.-H.; Riedl, T.; Lang, E.; Becker, D.; Dobbertin, T.; Kowalsky, W.
2007-09-01
One of the unique selling propositions of OLEDs is their potential to realize highly transparent devices over the visible spectrum. This is because organic semiconductors provide a large Stokes-Shift and low intrinsic absorption losses. Hence, new areas of applications for displays and ambient lighting become accessible, for instance, the integration of OLEDs into the windshield or the ceiling of automobiles. The main challenge in the realization of fully transparent devices is the deposition of the top electrode. ITO is commonly used as transparent bottom anode in a conventional OLED. To obtain uniform light emission over the entire viewing angle and a low series resistance, a TCO such as ITO is desirable as top contact as well. However, sputter deposition of ITO on top of organic layers causes damage induced by high energetic particles and UV radiation. We have found an efficient process to protect the organic layers against the ITO rf magnetron deposition process of ITO for an inverted OLED (IOLED). The inverted structure allows the integration of OLEDs in more powerful n-channel transistors used in active matrix backplanes. Employing the green electrophosphorescent material Ir(ppy) 3 lead to IOLED with a current efficiency of 50 cd/A and power efficiency of 24 lm/W at 100 cd/m2. The average transmittance exceeds 80 % in the visible region. The on-set voltage for light emission is lower than 3 V. In addition, by vertical stacking we achieved a very high current efficiency of more than 70 cd/A for transparent IOLED.
Design of 6 switched 3-level inverter with RL load
Directory of Open Access Journals (Sweden)
Ali Saygın
2016-10-01
Full Text Available In this study, an alternative topology to multilevel inverter topologies is given. 6 IGBT seminconductor switches are used in this topology and coupled inductors are used in the output stage of the inverter. Using coupled inductors voltages, the 6 switched 3-level inverter has been obtained. In the simulation study, Proportional Integral (PI controller has been used. By using the data taken from controller, the required switching signals have been produced for a 6 switched 3-level inverter. These signals have been taken by using space vector pulse width modulation technique. Using Computer Aided Design (CAD analysis a RL load that have 10 Ω and 0.2 H values is simulated and inverter performance has been investigated.
Z - Source Multi Level Inverter Based PV Generation System
Directory of Open Access Journals (Sweden)
T. Lakhmi kanth
2014-09-01
Full Text Available In this paper a novel technique of Z-Source multilevel Inverter based PV Generation system is implemented and simulated using MATLAB-Simulink simulation software. The Photovoltaic cells are healthier option for converting solar energy into electricity. Due to high capital cost and low efficiency PV cells have not yet been a fully smart choice for electricity users. To enhance the performance of the system, Z-Source multi level inverter can be used in place of conventional Voltage Source Inverter (VSI in Solar Power Generation System. The PV cell model is developed using circuit mathematical equations. The Z-Source multilevel inverter is modeled to realize boosted DC to AC conversion (inversion with low THD. Outcome shows that the energy conversion efficiency of ZSMLI is a lot improved as compared to conventional voltage Source Inverter (VSI. By doing FFT analysis we can know the total THD.
Photovoltaic Inverter Controllers Seeking AC Optimal Power Flow Solutions
Energy Technology Data Exchange (ETDEWEB)
Dall' Anese, Emiliano; Dhople, Sairaj V.; Giannakis, Georgios B.
2016-07-01
This paper considers future distribution networks featuring inverter-interfaced photovoltaic (PV) systems, and addresses the synthesis of feedback controllers that seek real- and reactive-power inverter setpoints corresponding to AC optimal power flow (OPF) solutions. The objective is to bridge the temporal gap between long-term system optimization and real-time inverter control, and enable seamless PV-owner participation without compromising system efficiency and stability. The design of the controllers is grounded on a dual ..epsilon..-subgradient method, while semidefinite programming relaxations are advocated to bypass the non-convexity of AC OPF formulations. Global convergence of inverter output powers is analytically established for diminishing stepsize rules for cases where: i) computational limits dictate asynchronous updates of the controller signals, and ii) inverter reference inputs may be updated at a faster rate than the power-output settling time.
Energy Technology Data Exchange (ETDEWEB)
Hoke, Anderson [National Renewable Energy Lab. (NREL), Golden, CO (United States); Nelson, Austin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Miller, Brian [National Renewable Energy Lab. (NREL), Golden, CO (United States); Chakraborty, Sudipta [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bell, Frances [SolarCity, San Mateo, CA (United States); McCarty, Michael [SolarCity, San Mateo, CA (United States)
2016-07-01
As PV and other DER systems are connected to the grid at increased penetration levels, island detection may become more challenging for two reasons: 1.) In islands containing many DERs, active inverter-based anti-islanding methods may have more difficulty detecting islands because each individual inverter's efforts to detect the island may be interfered with by the other inverters in the island. 2.) The increasing numbers of DERs are leading to new requirements that DERs ride through grid disturbances and even actively try to regulate grid voltage and frequency back towards nominal operating conditions. These new grid support requirements may directly or indirectly interfere with anti-islanding controls. This report describes a series of tests designed to examine the impacts of both grid support functions and multi-inverter islands on anti-islanding effectiveness. Crucially, the multi-inverter anti-islanding tests described in this report examine scenarios with multiple inverters connected to multiple different points on the grid. While this so-called 'solar subdivision' scenario has been examined to some extent through simulation, this is the first known work to test it using hardware inverters. This was accomplished through the use of power hardware-in-the-loop (PHIL) simulation, which allows the hardware inverters to be connected to a real-time transient simulation of an electric power system that can be easily reconfigured to test various distribution circuit scenarios. The anti-islanding test design was a modified version of the unintentional islanding test in IEEE Standard 1547.1, which creates a balanced, resonant island with the intent of creating a highly challenging condition for island detection. Three common, commercially available single-phase PV inverters from three different manufacturers were tested. The first part of this work examined each inverter individually using a series of pure hardware resistive-inductive-capacitive (RLC
Novel T-Z source inverter with high voltage gain and reduced transformer turn ratio
DEFF Research Database (Denmark)
Mostaan, Ali; Sharifi Malfejani, Saeed; Soltani, Mohsen;
2015-01-01
Novel voltage source inverter based on the Z source inverter structure is introduced in this paper. In this new inverter, two inductors of the impedance network in conventional Z source inverter are replaced with two transformers or coupled inductors, but unlike the T-Z source inverter that it......'s voltage gain is raised with increasing the transformers turn ratio, the voltage gain in the proposed inverter is raised with lowering the transformer turn ratio. Therefore, transformers with lower turn ratio are required in the proposed inverter in compare with T- Z source inverter that can lead to lower...
International Nuclear Information System (INIS)
The three-level scaling approach was developed for the scientific design of an integral test facility and then it was applied to the design of the scaled facility known as the Purdue University Multi-Dimensional Integral Test Assembly (PUMA). The NRC technical program group for severe accident scaling developed the conceptual framework for this scaling methodology. The present scaling method consists of the integral system scaling, whose components comprise the first two levels, and the phenomenological scaling constitutes the third level of scaling. More specifically, the scaling is considered as follows: (1) the integral response function scaling, (2) control volume and boundary flow scaling, and (3) local phenomena scaling. The first two levels are termed the top-down approach while the third level is the bottom-up approach. This scheme provides a scaling methodology that is practical and yields technically justifiable results. It ensures that both the steady state and dynamic conditions are simulated within each component, and also scales the inter-component mass and energy flows as well as the mass and energy inventories within each component. (orig.)
Vas, Zoltán; Fuisz, Tibor I; Fehérvári, Péter; Reiczigel, Jenő; Rózsa, Lajos
2013-04-01
Brood parasitic birds, their foster species and their ectoparasites form a complex coevolving system composed of three hierarchical levels. However, effects of hosts' brood parasitic life-style on the evolution of their louse (Phthiraptera: Amblycera, Ischnocera) lineages have never been tested. We present two phylogenetic analyses of ectoparasite richness of brood parasitic clades. Our hypothesis was that brood parasitic life-style affects louse richness negatively across all avian clades due to the lack of vertical transmission routes. Then, narrowing our scope to brood parasitic cuckoos, we explored macroevolutionary factors responsible for the variability of their louse richness. Our results show that taxonomic richness of lice is lower on brood parasitic clades than on their nonparasitic sister clades. However, we found a positive covariation between the richness of cuckoos' Ischnoceran lice and the number of their foster species, possibly due to the complex and dynamic subpopulation structure of cuckoo species that utilize several host species. We documented diversity interactions across a three-level host parasite system and we found evidence that brood parasitism has opposing effects on louse richness at two slightly differing macroevolutionary scales, namely the species richness and the genera richness. PMID:23550748
Directory of Open Access Journals (Sweden)
Qinghua Pang
2014-01-01
Full Text Available Considering the market demand is stochastic and dependent on price, this paper shows that the revenue-sharing contract could coordinate a three-level supply chain consisting of one manufacturer, one distributor, and one retailer under normal environment. However, the original revenue-sharing contract cannot coordinate the supply chain under disruptions in circumstances of certain incidents leading to significant changes in market demand and causing additional deviation costs. To solve the problem, this essay introduces two improved forms of revenue-sharing contract: a mixed contract form based on a quantity discount policy and a pure form, which are characterized by antidisruption ability. The model of improved revenue-sharing contract is optimized when the market demand is in the additive form or in the multiplicative form with price dependent demand. Formulas are given to calculate the optimal contract parameters. Finally, this essay demonstrates the accuracy of the model of improved revenue-sharing contract with the help of numerical examples.
Dynamics of a three-level V-type atom driven by a cavity photon and microwave field
Yan-Li, Xue; Shi-Deng, Zhu; Ju, Liu; Ting-Hui, Xiao; Bao-Hua, Feng; Zhi-Yuan, Li
2016-04-01
We discuss the dynamics of a three-level V-type atom driven simultaneously by a cavity photon and microwave field by examining the atomic population evolution. Owing to the coupling effect of the cavity photon, periodical oscillation of the population between the two upper states and the ground state takes place, which is the well-known vacuum Rabi oscillation. Meanwhile, the population exchange between the upmost level and the middle level can occur due to the driving action of the external microwave field. The general dynamic behavior is the superposition of a fast and a slow periodical oscillation under the cooperative and competitive effect of the cavity photon and the microwave field. Numerical results demonstrate that the time evolution of the population is strongly dependent on the atom-cavity coupling coefficient g and Rabi frequency Ω e that reflects the intensity of the external microwave field. By modulating the two parameters g and Ω e, a large number of population transfer behaviors can be achieved. Project supported by the National Natural Science Foundation of China (Grant Nos. 11434017 and 11374357) and the National Basics Research Program of China (Grant No. 2013CB632704).
Indian Academy of Sciences (India)
Mihir Ranjan Nath; Surajit Sen; Asoke Kumar Sen; Gautam Gangopadhyay
2008-07-01
We develop a scheme to construct the Hamiltonians of the lambda-, vee- and cascade-type three-level configurations using the generators of (3) group. It turns out that this approach provides a well-defined selection rule to give different Hamiltonians for each configuration. The lambda- and vee-type configurations are exactly solved with different initial conditions while taking the two-mode classical and quantized fields. For the classical field, it is shown that the Rabi oscillation of the lambda model is similar to that of the vee model and the dynamics of the vee model can be recovered from lambda model and vice versa simply by inversion. We then proceed to solve the quantized version of both models by introducing a novel Euler matrix formalism. It is shown that this dynamical symmetry exhibited in the Rabi oscillation of two configurations for the semiclassical models is completely destroyed on quantization of the field modes. The symmetry can be restored within the quantized models when both field modes are in the coherent states with large average photon number which is depicted through the collapse and revival of the Rabi oscillations.
Etxeberria, A.; Vechiu, I.; Baudoin, S.; Camblong, H.; Kreckelbergh, S.
2014-02-01
The increasing use of distributed generators, which are mainly based on renewable sources, can create several issues in the operation of the electric grid. The microgrid is being analysed as a solution to the integration in the grid of the renewable sources at a high penetration level in a controlled way. The storage systems play a vital role in order to keep the energy and power balance of the microgrid. Due to the technical limitations of the currently available storage systems, it is necessary to use more than one storage technology to satisfy the requirements of the microgrid application. This work validates in simulations and experimentally the use of a Three-Level Neutral Point Clamped converter to control the power flow of a hybrid storage system formed by a SuperCapacitor and a Vanadium Redox Battery. The operation of the system is validated in two case studies in the experimental platform installed in ESTIA. The experimental results prove the validity of the proposed system as well as the designed control algorithm. The good agreement among experimental and simulation results also validates the simulation model, that can therefore be used to analyse the operation of the system in different case studies.
A location-inventory model for distribution centers in a three-level supply chain under uncertainty
Directory of Open Access Journals (Sweden)
Ali Bozorgi-Amiri
2013-01-01
Full Text Available We study a location-inventory problem in a three level supply chain network under uncertainty, which leads to risk. The (r,Q inventory control policy is applied for this problem. Besides, uncertainty exists in different parameters such as procurement, transportation costs, supply, demand and the capacity of different facilities (due to disaster, man-made events and etc. We present a robust optimization model, which concurrently specifies: locations of distribution centers to be opened, inventory control parameters (r,Q, and allocation of supply chain components. The model is formulated as a multi-objective mixed-integer nonlinear programming in order to minimize the expected total cost of such a supply chain network comprising location, procurement, transportation, holding, ordering, and shortage costs. Moreover, we develop an effective solution approach on the basis of multi-objective particle swarm optimization for solving the proposed model. Eventually, computational results of different examples of the problem and sensitivity analysis are exhibited to show the model and algorithm's feasibility and efficiency.
Multilayer Control for Inverters in Parallel Operation without Intercommunications
DEFF Research Database (Denmark)
Hua, Ming; Hu, Haibing; Xing, Yan;
2012-01-01
among the inverters. The second layer is designed to compensate the voltage deviations caused by the mentioned droop control, thus improving the load-voltage regulation of the system. The third layer is a quasi-synchronization control aiming to roughly adjust the angle of the inverter to be close......In this paper, a multilayer control is proposed for inverters able to operate in parallel without intercommunications. The first control layer is an improved droop method that introduces power proportional terms into the conventional droop scheme, letting both active and reactive power to be shared...
Optimized Pulse Width Modulation for transformerless active-NPC inverters
DEFF Research Database (Denmark)
Achilladelis, Nikolaos; Koutroulis, Eftichios; Blaabjerg, Frede
2014-01-01
The transformerless DC/AC inverter topologies are employed in Photovoltaic systems in order to improve the power conversion efficiency, power density and cost. The Active-Neutral Point Clamped (Active-NPC) transformerless inverters have the advantage of achieving better thermal balance among...... their power semiconductors. In this paper, a new modulation technique is proposed for optimally controlling the power switches employed in transformerless Active-NPC inverters. The design results demonstrate that compared to the existing PWM strategies, using the proposed method results in lower total power...
Design of a Broadband Inverted Conical Quadrifilar Helix Antenna
Directory of Open Access Journals (Sweden)
Jingyan Mo
2016-01-01
Full Text Available This paper introduces the design of a broadband inverted conical circularly polarized quadrifilar helix antenna (QHA. The antenna has many good characteristics, including wide beam and broad bandwidth, which are achieved by utilizing inverted conical geometry and adjusting the dimensions of the inverted conical support. The antenna is fed by a wideband network to provide 90° phase difference between the four arms with constant amplitude. The antenna impedance and axial ratio bandwidth values are more than 39% and 31.5%, respectively. The measured results coincide well with the simulated ones, which verified the effectiveness of the proposed design.
Photovoltaic Simplified Boost Z Source Inverter for Ac Module Applications
Directory of Open Access Journals (Sweden)
J. Sam Alaric
2014-08-01
Full Text Available This study mainly proposed PV z source boost inverter used to boundary grid or ac module applications. Separate types of converter used for solar system due to its current lagging, here capacitor multiplier based boost converter introduced for maintain the current lagging and voltage gain. Here, the switched inductor z source inverter implemented for grid interface. Proposed z source inverter is controlled by pulse width modulation. A simplified capacitor multiplier controlled by continuous conduction mode, A detailed topology analysis and a generalized discussion are given. The multiplier boost converter has the merits of maintain voltage level and reducing cost and current lagging. Simulation results are implemented and analysis MATLAB software.
Electric machine and current source inverter drive system
Hsu, John S
2014-06-24
A drive system includes an electric machine and a current source inverter (CSI). This integration of an electric machine and an inverter uses the machine's field excitation coil for not only flux generation in the machine but also for the CSI inductor. This integration of the two technologies, namely the U machine motor and the CSI, opens a new chapter for the component function integration instead of the traditional integration by simply placing separate machine and inverter components in the same housing. Elimination of the CSI inductor adds to the CSI volumetric reduction of the capacitors and the elimination of PMs for the motor further improve the drive system cost, weight, and volume.
Intelligence Controller for STATCOM Using Cascaded Multilevel Inverter
Directory of Open Access Journals (Sweden)
C. C. Asir Rajan
2010-01-01
Full Text Available This paper presents a special gating pattern swapping technique for cascaded multilevel inverter, which is used for STATCOM.By using this technique besides minimizing the harmonic level, the inverter unit fundamental output voltages areequalized. Therefore, all the inverter units in each phase leg can equally share the exchanged active and reactive powerwith the utility grid. This greatly helps the dc-link voltages balancing control. PI Control is employed for improving performance.Fuzzy control is employed to the system for enhancing transient stability. The performance is analyzed usingdigital simulation.
Optimal Design of Modern Transformerless PV Inverter Topologies
DEFF Research Database (Denmark)
Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede
2013-01-01
The design optimization of H5, H6, neutral point clamped, active-neutral point clamped, and conergy-NPC transformerless photovoltaic (PV) inverters is presented in this paper. The components reliability in terms of the corresponding malfunctions, affecting the PV inverter maintenance cost during...... clamped, active-neutral point clamped and conergy-NPC PV inverters designed using the proposed optimization process feature lower levelized cost of generated electricity and lifetime cost, longer mean time between failures and inject more PV-generated energy into the electric grid than their nonoptimized...... counterparts, thus maximizing the total economic benefit obtained during the operational time of the PV system....
An iterative method to invert the LTSn matrix
Energy Technology Data Exchange (ETDEWEB)
Cardona, A.V.; Vilhena, M.T. de [UFRGS, Porto Alegre (Brazil)
1996-12-31
Recently Vilhena and Barichello proposed the LTSn method to solve, analytically, the Discrete Ordinates Problem (Sn problem) in transport theory. The main feature of this method consist in the application of the Laplace transform to the set of Sn equations and solve the resulting algebraic system for the transport flux. Barichello solve the linear system containing the parameter s applying the definition of matrix invertion exploiting the structure of the LTSn matrix. In this work, it is proposed a new scheme to invert the LTSn matrix, decomposing it in blocks and recursively inverting this blocks.
Closed Loop Analysis of Multilevel Inverter fed Drives
Directory of Open Access Journals (Sweden)
Bharath VS
2014-05-01
Full Text Available This paper deals with the simulation and implementation of multilevel inverter for drives application. Here the focuses will be on improving the efficiency of the multilevel inverter and quality of output voltage waveform. The circuit is developed towards high efficiency, high performance, and low cost, simple control scheme. Harmonics Elimination were implemented to reduce the Total Harmonics Distortion (THD value which is achieved by selecting appropriate switching angles. In this paper to determine the performance of rectifier, steady state analysis is done. Furthermore, the merits of multilevel inverter topology are inherited.Closed loop control is done to analysis the stability of the system.
Design of New Single-phase Multilevel Voltage Source Inverter
Directory of Open Access Journals (Sweden)
Rasoul Shalchi Alishah
2014-07-01
Full Text Available Multilevel inverters with more number of levels can produce high quality voltage waveforms. In this paper, a new single-phase structure for multilevel voltage source inverter is proposed which can generate a large number of levels with reduced number of IGBTs, gate driver circuits and diodes. Three algorithms for determination of dc voltage sources’ magnitudes are presented which provide odd and even levels at the output voltage waveform. A comparison is presented between proposed multilevel inverter and conventional cascade topology. The proposed topology is analyzed by the experimental and simulation results.
Six transformer based asymmetrical embedded Z-source inverters
DEFF Research Database (Denmark)
Wei, Mo; Poh Chiang, Loh; Chi, Jin;
2013-01-01
Embedded/Asymmetrical embedded Z-source inverters were proposed to maintain smooth input current/voltage across the dc source and within the impedance network, remain the shoot-through feature used to boost up the dc-link voltage without adding bulky filter at input side. This paper introduces a ...... a class of transformer based asymmetrical embedded Z-source inverters which keep the smooth input current and voltage while achieving enhanced voltage boost capability. The presented inverters are verified by laboratory prototypes experimentally....
Inverted Metamorphic Multijunction (IMM) Cell Processing Instructions
Energy Technology Data Exchange (ETDEWEB)
Duda, A.; Ward, S.; Young, M.
2012-02-01
This technical report details the processing schedule used to fabricate Inverted Metamorphic Multijunction (IMM) concentrator solar cells at The National Renewable Energy Laboratory (NREL). These devices are used as experimental test structures to support the research at NREL that is focused on increasing the efficiency of photovoltaic power conversion. They are not intended to be devices suitable for deployment in working concentrator systems primarily because of heat sinking issues. The process schedule was developed to be compatible with small sample sizes and to afford relatively rapid turn-around times, in support of research efforts. The report describes the use of electro deposition of gold for both the back and front contacts. Electro-deposition is used because of its rapid turn around time and because it is a benign metallization technique that is seldom responsible for damage to the semiconductors. The layer transfer technique is detailed including the use of a commercially available adhesive and the etching away of the parent gallium arsenide substrate. Photolithography is used to define front contact grids as well as the mesa area of the cell. Finally, the selective wet chemical etchant system is introduced and its use to reveal the back contact is described.
Grid Connected Five-level Dual-Buck Full-bridge Inverter With High Efficiency%高效率五电平双降压式全桥并网逆变器
Institute of Scientific and Technical Information of China (English)
张犁; 孙农; 邢岩
2012-01-01
为提高并网逆变器的变换效率,提出一种新颖的五电平双降压式全桥并网逆变器,它由三电平双降压式全桥拓扑、输入分压电容和钳位支路组合得到。其滤波电感和开关器件的电压阶梯仅为输入电压的一半,故磁性元件体积小、质量轻,且每个开关周期仅有一个开关管高频动作,降低了开关损耗。分析了该拓扑的工作原理和调制策略,并分别搭建五电平和三电平双降压式全桥并网逆变器实验样机进行效率比较。实验结果表明,所提五电平拓扑的欧洲效率较三电平拓扑高出0.5%。由三电平双降压式半桥拓扑与两电平桥臂组合,提出另外2种五电平双降压式全桥并网逆变器拓扑。最后对提出的3种拓扑的损耗和成本进行了详细的分析和对比。%In order to improve the efficiency of the grid-tied inverter,a novel five-level dual Buck full bridge inverter,which s derived from a three-level dual Buck full bridge inverter by adding two input split capacitors and a clamping circuit,was proposed.In the proposed inverter,the step voltages both on the filter inductor and across the switches are only half of the input voltage,resulting in a smaller size of the inductor.Furthermore,only one of these switches is operating at high switching frequency in any switching cycle,thus reducing switching losses.The operation principle and modulation strategy of the proposed inverter were analyzed.In order to make comparison,the proposed inverter prototype and a three-level inverter prototype were built respectively.Efficiency measurement show that the proposed inverter gains 0.5% higher Europe efficiency than the three-level inverter.Another two five-level dual Buck full bridge inverters were derived by combining a three-level dual Buck half bridge inverter and a two-level half bridge topology.These three proposed inverters were analyzed and compared in details in terms of power losses and cost.
Directory of Open Access Journals (Sweden)
Riyadh G. Omar
2014-12-01
Full Text Available Four-leg voltage source inverter is an evolution of the three-leg inverter, and was ought about by the need to handle the non-linear and unbalanced loads. In this work Matlab/ Simulink model is presented using space vector modulation technique. Simulation results for worst conditions of unbalanced linear and non-linear loads are obtained. Observation for the continuity of the fundamental inverter output voltages vector in stationary coordinate is detected for better performance. Matlab programs are executed in block functions to perform switching vector selection and space vector switching.
Directory of Open Access Journals (Sweden)
José Luis Moletta
2014-02-01
Full Text Available The objective of this experiment was to evaluate quantitative and qualitative characters of carcass and meat from bulls and steers finished in feedlot during a 116 day period, in individual stalls and fed with a diet of corn silage and three levels of concentrate (0.70; 0.97 and 1.23% of body weight. The concentrate was formulated with 25% soybean meal, 73% of ground corn grain 1% of a mineral mix and 1% of limestone. A total of 169 composite Purunã animals, being 94 bulls and 75 steers with average age of 20 months. The interaction between physiological condition and level of concentrate was not significant (P>0.05 for any of the studied variables. Likewise, no effect of level of concentrate was detected upon the same traits. The bulls presented heavier slaughter weight (493.1 kg in comparison with the steers (450.0 kg as well as higher carcass yield (55.2 vs. 53.5%, resulting in a hot carcass weight 12.1% heavier than bulls animals, though with a lower degree of carcass finishing (3.6 vs. 4.2 mm, respectively. Bulls produced carcasses with better conformation and higher area of Longissimus dorsi (68.6 vs. 63.3 cm2, and higher percentage of muscle in comparison with castrated (66.5 vs. 62.8%. The meat from bulls was darker and with lower degree of marbling in relation to steers. Nevertheless, no differences were observed for tenderness nor for juiciness, though steers had more palatable meat.
Inverted cone-shaped all-silicon photonic nanoresonators
Schmitt, Sebastian W; Christiansen, Silke H
2015-01-01
A novel type of photonic resonator based on a silicon nanostructure with inverted cone geometry is demonstrated. After excitation with visible light, individual inverted nanocones show near-infrared photonic modes with a high quality factor (Q). A thorough mode analysis reveals that this type of nanocavity geometry sustains a multitude of strongly confined whispering gallery modes, which are characterized by efficient and directional, vertical out-coupling of near-infrared light. Investigating the relation between the inverted nanocone geometry and the mode formation leads to simple design rules that permit to control the number and wavelength of the hosted modes. The unique optical features of the suitably designed all-Si inverted nanocone resonators will raise great interest in vibrant research fields such as silicon nanolasing, optoelectronics, sensing or solar light concentration.
Reliability Assessment of Transformerless PV Inverters considering Mission Profiles
Directory of Open Access Journals (Sweden)
Yongheng Yang
2015-01-01
Full Text Available Due to the small volume and high efficiency, transformerless inverters have gained much popularity in grid-connected PV applications, where minimizing leakage current injection is mandatory. This can be achieved by either modifying the modulation schemes or adding extra power switching devices, resulting in an uneven distribution of the power losses on the switching devices. Consequently, the device thermal loading is redistributed and thus may alter the entire inverter reliability performance, especially under a long-term operation. In this consideration, this paper assesses the device reliability of three transformerless inverters under a yearly mission profile (i.e., solar irradiance and ambient temperature. The mission profile is translated to device thermal loading, which is used for lifetime prediction. Comparison results reveal the lifetime mismatches among the power switching devices operating under the same condition, which offers new thoughts for a robust design and a reliable operation of grid-connected transformerless PV inverters with high efficiency.
High Radiation Resistance Inverted Metamorphic Solar Cell Project
National Aeronautics and Space Administration — The innovation in this SBIR Phase II project is the development of a unique triple junction inverted metamorphic technology (IMM), which will enable the...
Mathematical modeling of elastic inverted pendulum control system
Institute of Scientific and Technical Information of China (English)
Chao XU; Xin YU
2004-01-01
Inverted pendulums are important objects of theoretical investigation and experiment in the area of control theory and engineering.The researches concentrate on the rigid finite dimensional models which are described by ordinary differential equations(ODEs).Complete rigidity is the approximation of practical models;Elasticity should be introduced into mathematical models in the analysis of system dynamics and integration of highly precise controller.A new kind of inverted pendulum,elastic inverted pendulum was proposed,and elasticity was considered.Mathematical model was derived from Hamiltonian principle and variational methods,which were formulated by the coupling of partial differential equations(PDE) and ODE.Because of infinite dimensional,system analysis and control of elastic inverted pendulum is more sophisticated than the rigid one.
Analysis and design of controllers for a double inverted pendulum
DEFF Research Database (Denmark)
Niemann, Hans Henrik; Poulsen, J K
2003-01-01
A physical control problem is studied with the μ methodology. The issues of modelling, uncertainty modelling, performance specification, controller design and laboratory implementation are discussed. The laboratory experiment is a double inverted pendulum placed on a cart. The limitations...
Study of Inverted Pendulum Robot Using Fuzzy Servo Control Method
Directory of Open Access Journals (Sweden)
Dazhong Wang
2012-09-01
Full Text Available The inverted pendulum robot is a classical problem in controls. The inherit instabilities in the setup make it a natural target for a control system. Inverted pendulum robot is suitable to use for investigation and verification of various control methods for dynamic systems. Maintaining an equilibrium position of the pendulum pointing up is a challenge as this equilibrium position is unstable. As the inverted pendulum robot system is nonlinear it is well‐suited to be controlled by fuzzy logic. In this paper, Lagrange method has been applied to develop the mathematical model of the system. The objective of the simulation to be shown using the fuzzy control method can stabilize the nonlinear system of inverted pendulum robot.
Application ofBoost Inverter to Multi Input PV system
Directory of Open Access Journals (Sweden)
G.SHINYVIKRAM
2014-11-01
Full Text Available With the shortage of the energy and ever increasing of the oil price, research on the renewable and green energy sources, especially the solar arrays and the fuel cells, becomes more and more important. How to achieve high step- up and high efficiency DC/DC converters is the major consideration in the renewable power applications due to the low voltage of PV arrays and fuel cells. The conventional boost converters increase the harmonics rate and add an extra stage of power conversion. This paper proposes a boost dc-ac inverter that can invert and boost the output voltage in a single stage. In this paper the proposed boost dc-ac inverter is applied to the solar power panels and is simulated using Simulink. The output results of the boost inverter are worthy promising.
Performance model for grid-connected photovoltaic inverters.
Energy Technology Data Exchange (ETDEWEB)
Boyson, William Earl; Galbraith, Gary M.; King, David L.; Gonzalez, Sigifredo
2007-09-01
This document provides an empirically based performance model for grid-connected photovoltaic inverters used for system performance (energy) modeling and for continuous monitoring of inverter performance during system operation. The versatility and accuracy of the model were validated for a variety of both residential and commercial size inverters. Default parameters for the model can be obtained from manufacturers specification sheets, and the accuracy of the model can be further refined using measurements from either well-instrumented field measurements in operational systems or using detailed measurements from a recognized testing laboratory. An initial database of inverter performance parameters was developed based on measurements conducted at Sandia National Laboratories and at laboratories supporting the solar programs of the California Energy Commission.
Scalable Video Coding with Invertible Sampling Lattice Conversion
Ishida, Takuma; 石田, 拓麿
2006-01-01
The goal of this study is to develop non-separable multi-rate systems integreted with invertible video format coversion in order to offer a spatio-temporal resoluton control function as a new option for scalable video coding.
Virtual Oscillator Control Maintains Grid Operations with High Inverter Penetrations
Energy Technology Data Exchange (ETDEWEB)
2016-06-01
VOC makes each inverter behave electrically like a spring, 'bouncing back' to its normal operating range when disturbed. Coupling these inverters electronically could result in a new way to stabilize power grids. VOC has been demonstrated in a microgrid using several small inverters. In addition, five custom-designed inverters have been built and will be tested with grid simulations at NREL using power hardware-in-the-loop technology. VOC may provide a simple method to keep microgrids stable -- a topic of growing interest as resilience to energy disruptions gains prominence. VOC may also provide a means to transition power grids from today's inertia-dominated systems to systems that do not rely on rotating machinery.
High Radiation Resistance Inverted Metamorphic Solar Cell Project
National Aeronautics and Space Administration — The innovation in the proposed SBIR Phase I project is the development of a unique triple unction inverted metamorphic technology (IMM), which will enable the...
Triple inverter pierce oscillator circuit suitable for CMOS
Wessendorf; Kurt O.
2007-02-27
An oscillator circuit is disclosed which can be formed using discrete field-effect transistors (FETs), or as a complementary metal-oxide-semiconductor (CMOS) integrated circuit. The oscillator circuit utilizes a Pierce oscillator design with three inverter stages connected in series. A feedback resistor provided in a feedback loop about a second inverter stage provides an almost ideal inverting transconductance thereby allowing high-Q operation at the resonator-controlled frequency while suppressing a parasitic oscillation frequency that is inherent in a Pierce configuration using a "standard" triple inverter for the sustaining amplifier. The oscillator circuit, which operates in a range of 10 50 MHz, has applications for use as a clock in a microprocessor and can also be used for sensor applications.
A Two-Stage Wind Grid Inverter with Boost Converter
Directory of Open Access Journals (Sweden)
Yanbo Che
2014-01-01
Full Text Available At present, the conversion efficiency of commercial small wind grid inverter is low, and, in case of low wind speed, the wind energy cannot be used efficiently. In order to resolve this problem, it is necessary to improve the topological structure and control strategy, and design a new small wind grid inverter. In this paper, we apply a two-voltage stage topology with boost converter. The boost circuit is to achieve the maximum power output of the wind energy by the segmented regulation, while the improved inverter topology realizes the overall system function with the former stage circuit. The experimental results show that the new wind grid inverter has superior performance in the low wind speed, and has the high quality energy output. This research has an important practical significance to improve the utilization of renewable energy.
Analysis and Modeling of Transformerless Photovoltaic Inverter Systems
DEFF Research Database (Denmark)
Kerekes, Tamas
demands. This continuously increasing consumption overloads the distribution grids as well as the power stations, therefore having a negative impact on power availability, security and quality. One of the solutions for overcoming this is the grid-connected photovoltaic (PV) system. PV inverter systems can...... be improved in terms of efficiency using transformerless topologies, but new problems related to leakage current need to be dealt with. The work presented in this thesis deals with analyzing and modeling of transfor-merless PV inverter systems regarding the leakage current phenomenon that can damage solar......, the objectives and limitations of the project are enumerated. The chapter finishes with the outline of the thesis. Chapter 2: Overview of grid connected PV systems, gives an overview about grid connected PV inverters, focusing on transformerless inverters and related safety issues. The parasitic capacitance...
SINGLE - PHASE INVERTER CONTROL TECHNIQUES FOR INTERFACING RENEWABLE ENERGY SOURCES
C.Nallasivam
2015-01-01
A novel current control technique is proposed to control power flow from a renewable energy source feeding a microgrid system through a three - phase parallel - connected inverter. The parallel - connected inverter ensures that the power flow from the grid with low - current total harmonic distortion even in the presence of nonlinear load. The renewable energy sources ar e paralleled, and the average of this constant sup...
SEPP-ZVS High Frequency Inverter Incorporating Auxiliary Switch
Ogiwara, Hiroyuki; Itoi, Misao; Nakaoka, Mutsuo
This paper presents a novel circuit topology to attain ZVS operation of a high frequency inverter over a wide range output power regulation using a PWM control technique by connecting an auxiliary switch to the conventional single ended push-pull (SEPP) ZVS high frequency inverter. A switching current is injected into the main switches via the auxiliary switch only during the short period between its turn-on and off times to supply a current required for its ZVS operation.
Grounding Effect on Common Mode Interference of Underground Inverter
Cheng, Qiang; Cheng, Ning; LI Zhen-shuang
2013-01-01
For the neutral point not grounded characteristics of underground power supply system in coal mine, this paper studied common mode equivalent circuit of underground PWM inverter, and extracted parasitic parameters of interference propagation path. The author established a common mode and differential mode model of underground inverter. Taking into account the rise time of PWM, the simulation results of conducted interference by Matlab software is compared with measurement spectrum on the AC s...
Resistance Spot Welding with Middelfrequency-Inverter Weling Gun
DEFF Research Database (Denmark)
Rasmussen, Mogens H.
The paper presents the results of investigations concerning the process stability and weldability lobes for uncoated sheets of 1.0 mm thickness when performing resistance spot welding with a middlefrequency-inverter welding gun......The paper presents the results of investigations concerning the process stability and weldability lobes for uncoated sheets of 1.0 mm thickness when performing resistance spot welding with a middlefrequency-inverter welding gun...
Tri-State Current Source Inverter With Improved Dynamic Performance
DEFF Research Database (Denmark)
Blaabjerg, Frede; Loh, Poh Chiang; Wong, Chow Pang;
2008-01-01
Traditional dc-ac current source inverter (CSI) has a right-half-plane (RHP) zero in its control-to-output transfer function. This RHP zero causes the inverter output to fall before rising when a step increase in command reference is required (commonly known as non-minimum-phase effect). To achie...... prototype for demonstrating its improved dynamic performance with no commutation difficulties introduced....
THD ANALYSIS OF DIFFERENT LEVELS IN DIODE CLAMPED INVERTER
Milind S Marathe; Vaibhav D Patil
2013-01-01
A multilevel inverter with assumed equal dc sources, the multilevel fundamental switching scheme is used to control the needed power electronics switches. Also, a method is presented where switching angles are computed such that a desired fundamental sinusoidal voltage is produced while at the same time certain higher order harmonics are eliminated. In this paper PWM switching technique in three, four, five, six-level diodeclamped multilevel inverter (DCMLI) has been tested in Matlab/Simulink...
Instantaneous Current Feedback Control Strategy on Buck Mode Inverter
Institute of Scientific and Technical Information of China (English)
2011-01-01
Control strategies for Buck mode inverter have important effect on static and dynamic characteristics, reliability, load capacity, and short-circuit resistance. Instantaneous current feedback control strategies include instantaneous inductor current feedback control and instantaneous capacitor current feedback control, both of which have essential difference. When the Buck mode inverter respectively adopts instantaneous inductor current and capacitor current feedback control strategies, characteristics of stability, output voltage and power, short circuit, nonlinear load and dynamic are fully investigated in this paper.
A New Green Power Inverter for Fuel Cells
DEFF Research Database (Denmark)
Andersen, Gert Karmisholt; Klumpner, Christian; Kjær, Søren Bækhøj;
2002-01-01
power to the grid. The proposed converter consists of an isolated dc-dc converter cascaded with a single phase H-bridge inverter. The dc-dc converter is a current-fed push-pull converter. A new dedicated voltage mode startup procedure has been developed in order to limit the inrush current during......%) and the inverter operates with a near unity power factor and a low current THD....
Harmonic Reduction In Five Level Inverter Based Dynamic Voltage Restorer
Directory of Open Access Journals (Sweden)
S. Leela
2010-12-01
Full Text Available This study deals with harmonic reduction in the five level inverter based Dynamic Voltage Restorer(DVR. The control of DV R that injects a voltage in series with a distribution feeder is presented. DVR is a power electronic controller that can protect sensitive loads from disturbances in supply system. DVR can regulate the voltage at the load. The simulation results of five level inverter based DVR are presented. The spectrum for the output voltage is also presented.
Invertible Clipping for Increasing the Power Efficiency of OFDM Amplification
Ragusa, Salvatore; Palicot, Jacques; Louët, Yves; Lereau, Christian
2006-01-01
International audience Large fluctuations of OFDM signal amplitude represent an important problem for power amplification in mobile communication systems. In this paper, we propose a new Peak-to-Average Power Ratio (PAPR) reduction method based on the well known clipping and filtering one. Called "invertible clipping", it is performed thanks to a "soft clipping function". Since this soft clipping can be inverted in reception side, degradations are compensated. The derived method benefits f...
A New Phase-Shifted Cascade High Voltage Inverter
Institute of Scientific and Technical Information of China (English)
Lau Eng Tin
2005-01-01
This paper presents a unique novel design of the phase-shifted cascade high voltage inverter. Thehigh voltage inverter utilizes fewer power switches and supplies a balance load. The usage of phase shifttransformer and phase shifting SPWM ensures that input and output harmonic wave content is low and outputvoltage change (du/dt) has a low rate, meeting all the requirements of the power authorities. The most out-standing feature is the energy saving with very fast cost recovery.