Showing papers in "Advances in Power Electronic in 2011"
TL;DR: In this article, the adaptive hysteresis current control (AHCC) has been introduced which produces hystresis bandwidth which instantaneously results in smoother and constant switching frequency.
Abstract: Hysteresis Current Control (HCC) is widely used due to its simplicity in implementation, fast and accurate response. However, the main issue is its variable switching frequency which leads to extraswitching losses and injecting high-frequency harmonics into the system current. To solve this problem, adaptive hysteresis current control (AHCC) has been introduced which produces hysteresis bandwidth which instantaneously results in smoother and constant switching frequency. In this paper the instantaneous power theory is used to extract the harmonic components of system current. Then fixed-band hysteresis current control is explained. Because of fixed-band variable frequency disadvantages, the adaptive hysteresis current control is explained that leads to fixing the switching frequency and reducing the high-frequency components in source current waveform. Due to these advantages of AHCC, the switching frequency and switching losses will be diminished appropriately. Some simulations are done in MATLAB/Simulink. The Fourier Transform and THD results of source and load currents and the instantaneous switching frequency diagram are discussed to prove the efficiency of this method. The Fourier Transform and THD results of source and load currents are discussed to prove the validity of this method.
43 citations
TL;DR: In this paper, a unique direct driven permanent magnet synchronous generator has been designed and constructed for wind turbines with full variable speed, which can maintain a high efficiency for the whole operational regime.
Abstract: A unique direct driven permanent magnet synchronous generator has been designed and constructed. Results from simulations as well as from the first experimental tests are presented. The generator has been specifically designed to be directly driven by a vertical axis wind turbine and has an unusually low reactance. Generators for wind turbines with full variable speed should maintain a high efficiency for the whole operational regime. Furthermore, for this application, requirements are placed on high generator torque capability for the whole operational regime. These issues are elaborated in the paper and studied through simulations. It is shown that the generator fulfils the expectations. An electrical control can effectively substitute a mechanical pitch control. Furthermore, results from measurements of magnetic flux density in the airgap and no load voltage coincide with simulations. The electromagnetic simulations of the generator are performed by using an electromagnetic model solved in a finite element environment.
35 citations
TL;DR: In this paper, a synchronization scheme for synchronous control of four inverters feeding six-phase drive on the base of an asymmetrical induction motor has been proposed, which has two sets of windings spatially shifted by 30 degrees.
Abstract: Novel method of space-vector-based pulse-width modulation (PWM) has been disseminated for synchronous control of four inverters feeding six-phase drive on the base of asymmetrical induction motor which has two sets of windings spatially shifted by 30 electrical degrees. Basic schemes of synchronized PWM, applied for control of four separate voltage-source inverters, allow both continuous phase voltages synchronization in the system and required power sharing between DC sources. Detailed MATLAB-based simulations show a behavior of six-phase system with continuous and discontinuous versions of synchronized PWM.
20 citations
TL;DR: In this article, a sensorless method for the estimation of the rotor position of the wound-rotor induction machine is described based on the MRAS methodology and consists in the comparison of two models for the evaluation of the active power transferred across the air gap: the reference model and the adaptive model.
Abstract: A sensorless method for the estimation of the rotor position of the wound-rotor induction machine is described in this paper. The method is based on the MRAS methodology and consists in the comparison of two models for the evaluation of the active power transferred across the air gap: the reference model and the adaptive model. The reference model obtains the power transferred across the air gap using directly available and measured stator variables. The adaptive model obtains the same quantity in function of electromotive forces and rotor currents that are measurable on the rotor position, which is under estimation. The method does not need any information about the stator or rotor flux and can be implemented in the rotor or in the stator reference frames with a hysteresis or with a PI controller. The stability analysis gives an unstable region on the rotor current dq plane. Simulation and experimental results show that the method is appropriate for the vector control of the doubly fed induction machine under the stability region.
18 citations
TL;DR: A series active filter and shunt active filter to minimize the power quality impact present in matrix converters instead of passive filter and compensates the sag and swell problems efficiently in matrix converter is proposed.
Abstract: This paper proposes a series active filter and shunt active filter to minimize the power quality impact present in matrix converters instead of passive filter. A matrix converter produces significant harmonics and nonstandard frequency components into load. The proposed system compensates the sag and swell problems efficiently in matrix converter. The proposed system has been tested and validated on the matrix converter using MATLAB/Simulink software. Simulated results confirm that the active power filters can maintain high performance for matrix converter.
9 citations
TL;DR: In this paper, a primary droop current-sharing controller that can integrate into voltage feedback controller and provide a low-cost and simple solution for parallel DC/DC converters system is presented.
Abstract: This paper presents a primary droop current-sharing controller that can integrate into voltage feedback controller and, thus, provides a low-cost and simple solution for parallel DC/DC converters system. From the equivalent small-signal model, a two-port network was adapted to describe the output and control variables for designing voltage and droop current-sharing loops. From the analysis results, the designed primary droop current-sharing controller will not affect the original voltage loop gain profile to let the DC/DC converter preserve desire control performance. After designing a stable DC/DC converter with primary droop current-sharing control, the stability of the interconnected parallel DC/DC converters system was studied. When the cable resistance is reduced, when the cable resistance is reduced, the interconnected system might be unstable. Finally, some simulation and experimental results demonstrated the effectiveness of the proposed controller in a prototype parallel DC/DC converters system.
6 citations
TL;DR: In this paper, a series compensated system with SSSC is presented, where the active series compensation is provided by a three-level twenty four-pulse series compensator, and the SSR characteristics of the combined system with constant reactive voltage control mode in series capacitors are investigated.
Abstract: The advent of series FACTS controllers, thyristor controlled series capacitor (TCSC) and static synchronous Series Compensator (SSSC) has made it possible not only for the fast control of power flow in a transmission line, but also for the mitigation of subsynchronous resonance (SSR) in the presence of fixed series capacitors. SSSC is an emerging controller and this paper presents SSR characteristics of a series compensated system with SSSC. The study system is adapted from IEEE first benchmark model (FBM). The active series compensation is provided by a three-level twenty four-pulse SSSC. The modeling and control details of a three level voltage source converter-(VSC)-based SSSC are discussed. The SSR characteristics of the combined system with constant reactive voltage control mode in SSSC has been investigated. It is shown that the constant reactive voltage control of SSSC has the effect of reducing the electrical resonance frequency, which detunes the SSR. The analysis of SSR with SSSC is carried out based on frequency domain method, eigenvalue analysis and transient simulation. While the eigenvalue and damping torque analysis are based on linearizing the D-Q model of SSSC, the transient simulation considers both D-Q and detailed three phase nonlinear system model using switching functions.
5 citations
TL;DR: In this paper, an efficient power factor correction converter is presented, where two boost-topology switching cells are interleaved to minimize EMI while operating at lower switching frequency and soft switching to minimize losses.
Abstract: An efficient power factor correction converter is presented. Two boost-topology switching cells are interleaved to minimize EMI while operating at lower switching frequency and soft switching to minimize losses. The result is a system with high conversion efficiency, able to operate in a pulse-width-modulation (PWM) way. Seven transition states of the ZVT converter in one switching period are described. In order to illustrate the operational principle key, implementation details, including simulations, are described. The validity of this converter is guaranteed by the obtained results.
4 citations
TL;DR: In this paper, the static synchronous compensator (STATCOM) is a shunt connected voltage source converter (VSC) based FACTS controller using GTOs employed for reactive power control.
Abstract: The static synchronous compensator (STATCOM) is a shunt connected voltage source converter (VSC) based FACTS controller using GTOs employed for reactive power control. A typical application of a STATCOM is for voltage regulation at the midpoint of a long transmission line for the enhancement of power transfer capability and/or reactive power control at the load centre. The PI controller-based reactive current controller can cause oscillatory instability in inductive mode of operation of STATCOM and can be overcome by the nonlinear feedback controller. The transient response of the STATCOM depends on the controller parameters selected. This paper presents a systematic method for controller parameter optimization based on genetic algorithm (GA). The performance of the designed controller is evaluated by transient simulation. It is observed that the STATCOM with optimized controller parameters shows excellent transient response for the step change in the reactive current reference. While the eigenvalue analysis and controller design are based on D-Q model, the transient simulation is based on both D-Q and 3-phase models of STATCOM (which considers switching action of VSC).
4 citations
TL;DR: In this paper, the heat transfer out of an IXZ210N50L MOSFET which is sandwiched between two identical heatsinks was analyzed and the results reveal that a linear decrease in heat flowing away from the top of the MOS FET when compared to the bottom of the FET for each step increase of drain current.
Abstract: MOSFET devices have developed significantly over the past few years to become the number one choice for high-power applications in power electronics and electronic communication. Commercially available devices (such as the IXYS RF manufactured) now operate into the VHF range with output RF powers of up to 300 W. They are optimized for linear operation and suitable for broadcast and communication applications. This paper presents the heat transfer out of an IXZ210N50L MOSFET which is sandwiched between two identical heatsinks. The results reveal a linear decrease in heat flowing away from the top of the MOSFET when compared to the bottom of the MOSFET for each step increase of drain current. Two graphs (representing the top and bottom heatsinks connected to the MOSFET device) contrast the temperature rise for the Bisink technique when the drain current through the IXZ210N50L MOSFET is kept constant at 5 A. The Bisink technique has the advantages of lower on-state resistances and higher output powers when compared to the traditional mounting using only one heatsink, resulting in improved reliability and performance. Results further reveal that the ambient temperature must be measured in the vicinity of the heatsink.
2 citations
TL;DR: In this paper, a discrete-time decoupled current control strategy is proposed to achieve a preferable solution to current coupling effect in the VSC-based three-phase three-line system.
Abstract: Accurate current control of the voltage source converters (VSCs) is one of the key research subjects in modern power electronics. To achieve a preferable solution to current coupling effect in the VSC-based three-phase three-line system, a discrete-time decoupled current control strategy is proposed in the paper. With integration of the α-β transform and two independent current controllers, the proposed methodology can effectively implement decoupled control of the three-phase currents, which can thereby eliminate the impact from the neutral-point voltage especially under asymmetrical loading conditions. Control performance under digital realization was characterized with extensive tests on a shunt active power filter (SAPF) platform. Both the simulative and experimental results have demonstrated that the SAPF could function well and thereby verified the feasibility and effectiveness of the proposed current control methodology.
TL;DR: In this paper, an analog behavioral model of high power gate turn-off thyristor (GTO) was developed based on the use of the realistic diode consideration of non-linear junctions.
Abstract: An analog behavioral model of high power gate turn-off thyristor (GTO) is developed in this paper. The fundamental methodology for the modeling of this power electronic circuit is based on the use of the realistic diode consideration of non-linear junctions. This modeling technique enables to perform different simulations taking into account the turn-on and turn-off transient behaviors in real-time. The equivalent circuits were simulated with analog software developed in our laboratory. It was shown that the tested simple and compact model allows the generation of accurate physical characteristics of power thyristors under dynamic conditions. The model understudy was validated with analog simulations based on operational amplifier devices.
TL;DR: A pulse-width modulator to drive three-phase AC motors performs a numerical modulation technique, but, in order to reduce hardware resources, a hybrid approach merging that calculated modulation with proportional modulation is proposed.
Abstract: A pulse-width modulator to drive three-phase AC motors is described. It performs a numerical modulation technique, also known as optimum or calculated modulation, but, in order to reduce hardware resources, a hybrid approach merging that calculated modulation with proportional modulation is proposed. The modulator is tested in a flash-based field programmable gate array (FPGA) implementation.
TL;DR: This paper proposes a quadratic linearization approach for PMSM based on the approximate linearization technique which does not introduce singularities and tuning of the linearizing transformation is proposed and verified using simulation.
Abstract: Many of the existing control methods for the permanent magnet synchronous motor (PMSM) either deal with steady state models or consider dynamic models under particular cases. A dynamic model of the PM machine allows powerful control-theoretic techniques such as linearization to be applied to the system. Existing exact feedback linearization of dynamic model of PMSM suffers from singularity issues. In this paper, we propose a quadratic linearization approach for PMSM based on the approximate linearization technique which does not introduce singularities. A MATLAB simulation is used to verify the effectiveness of the linearization technique proposed. Also, to account for higher-order and unmodelled dynamics of PMSM, tuning of the linearizing transformation is proposed and verified using simulation.
TL;DR: In this paper, the authors present a stability analysis of train converters in order to evaluate how the controller parameters affect the absorbed current, considering the time-variant nature of the system for the correct tuning of the feedback proportional-integral PI controller.
Abstract: This paper presents a stability analysis of train converters in order to evaluate how the controller parameters affect the absorbed current. The new dynamic model presented in this paper is capable of considering the time-variant nature of the system for the correct tuning of the feedback proportional-integral PI controller, applying a current controlled modulation technique never used in high-power traction converters. The reduction of the harmonic content of the current absorbed by a converter employed at the input stage onboard high-speed trains is really important, considering the interaction with the signaling system set up for traffic control. A computer model of the converter, considering both the power and the control structure, has also been implemented in order to deliver a validated tool for the developed theoretical analysis.