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EPE-PEMC 2006 - Topic 03: CONTROL OF POWER CONVERTERS
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	A Novel Digital Synchronization Control Strategy for Parallel-Connected Inverters   By Bangyin Liu, Shanxu Duan, Yong Kang, Jian Chen	[View]   [Download]
Abstract: This paper proposed a kind of digital synchronization control strategy based on re-modulation SPWM, and analyzed the control precision and harmonics of the technology. The SPWM re-modulation can decrease the difference of synchronization in phase lock loop control for fully digital inverters in parallel operation. Simulation and experimental results are included to show that this method can improve the synchronization control precision, insure the stability of parallel inverters system and suppress the circulating current between inverter modules.
	A Novel Multi-Dimensional SVPWM Strategy of Multiphase Motor Drives   By Shan Xue, Xuhui Wen, Feng Zhao	[View]   [Download]
Abstract: Multiphase motor drives are multi-dimensional systems, so multiphase SVPWM must be implemented in a multi-dimensional vector space to satisfy motor’s control requirements. In this paper, a novel multi-dimensional multiphase SVPWM strategy, which could synthesize the required voltage vectors not only in d-q subspace but also in other subspaces, is presented. Therefore, this strategy can control all voltage and current harmonics which contribute to the torque positively. Throughout this paper, a five-phase permanent motor drive system is developed as an example, and simulation and experimental results verify the validity of the proposed method. For the purpose of comparison, conventional SVPWM is also tested.
	A Novel Output-Voltage Dip Preventing Circuit for a Synchronous Buck Converter with a Pre-Biased Voltage   By Pei-Yuan Chen, Dan Chen, Fu-Yuan Shih	[View]   [Download]
Abstract: In many Buck converter applications, soft start feature with pre-biased output voltage condition is often necessary to avoid undesirable effects such as in-rush start current, possible inductor saturation, and output voltage overshoot during power-up period. However, in a synchronous Buck converter configuration, such starting condition would lead to output voltage temporary dipping during power-up, which is disallowed in many applications. In this paper, a novel control circuit is proposed to mitigate such a problem. Circuit-level SPICE simulations were conducted to verify the concept. The proposed circuit concept was experimentally verified by using discrete components at the breadboard level. Although the experimental verification was done with discrete components, however, the circuit was conceived with the intention of integrated circuit fabrication.
	A Novel Three-Phase Software Phase-Locked Loop   By William Phipps, Richard Duke, Michael Harrison	[View]   [Download]
Abstract: This paper describes the development of a novel three-phase phase-locked loop (PLL) used to compensate for mains variations by being incorporated as part of a feedforward loop in a three-phase telecommunications power converter. A telecommunications converter must comply with industry standards, in particular the psophometric noise standard CCIF-1951; this is achieved by controlling the output voltage ripple from the dc-dc converter. It is required that psophometric compliance is maintained under expected mains variations documented in the EN50160 power quality standard. The software PLL is simulated and performance characteristics show a high degree of noise rejection while also maintaining good dynamic performance.
	A Powerful Switching Frequency Limitation in Sliding Mode Control   By Jean-Christophe Olivier, Jean-Claude Le Claire, Luc Loron	[View]   [Download]
Abstract: This paper deals with a new analog system which limits the switching frequency in sliding mode control. This analog process consists in adding a second order filter, just before the relay function. It is possible to get a very fast dynamics and a behavior similar to the one predicted by the sliding mode theory. This investigated method is involved in a voltage power supply, which can be used as Uninterruptible Power Supply, with bandwidth greater than 2000Hz. In short, the investigated frequency control method requires a simple analog filter and offers to the users an accurate tracking of the reference signal with a very high robustness.
	A Three-Phase Power Source with Low THD for Energy Meters Calibration   By Gorazd Modrijan, Peter Zajec, Janez Nastran, Henrik Lavric, Danijel Voncina	[View]   [Download]
Abstract: The paper presents an experimental three-phase electronic phantom power source with special requirements, designed for calibrating mostly electronic energy meters. The three-phase power calibrator arrangement generates a variable phantom power of up to 19.2 kVA per phase. Two different power amplifiers, i.e. a voltage and a transconductance amplifier, and other individual components of the power calibrator are introduced and explained. A control method suitable for reducing effects of nonlinear periodic disturbances on electrical quantities, i.e. the output waveforms of voltage and current sources, is explained. The focus is on the theory of a modified repetitive control method based on a procedure with a recurrent integral action distributing the controlled signal in a certain number of intervals and subsequently correcting each interval separately and independently of the remaining intervals. Results acquired with the help of the experimental source are presented.
	Advanced DSP Control of 3-level DC/AC Converter for Variable-Speed PMSG   By Mariusz Malinowski, Wojciech Kolomyjski, Marian P. Kazmierkowski, Sebastian Stynski	[View]   [Download]
Abstract: This paper proposes an advanced control of threephase three-level neutral point clamped (3L-NPC) PWM converter connecting a permanent magnet synchronous generator (PMSG) to a grid. Control scheme is mainly based on active and reactive power loops and contains following additional blocks: virtual flux and filter-capacitor voltage estimators for sensorless operation, active damping (AD) of possible resonances in LCL filter connecting converter to the grid, PWM modulator with DC link voltage balancing and minimization of switching losses. It is shown that the proposed control method exhibits several features as: sensorless operation, robust algorithm, minimization of switching losses as well as simple tuning procedure of AD. Simulation and experimental results have proven a good performance and verified the validity of the proposed system.
	Comparison of Methods for Continuous Transition of Space Vector PWM into Six-Step Mode   By Zdenek Peroutka, Tomas Glasberger	[View]   [Download]
Abstract: The aim of this paper is the comparison of different space vector PWM (SVPWM) strategies enabling the continuous transition into the six-step mode. One of the important factors to be explored is the frequency analysis of the motor quantities in order to be able to evaluate the possible impact of the drive on the traction mains – specifically the impact on the railway signaling.
	Comparisons of Three Control Schemes for Adaptive Voltage Position (AVP) Droop for VRMs Applications   By Martin Lee, Dan Chen, Chih-Wen Liu, Kevin Huang, Eddie Tseng, Ben Tai	[View]   [Download]
Abstract: Based on small-signal models, comparisons were made for three commonly-used control schemes for adaptive voltage position for VRM applications. Performances compared include output impedance, control stability, and audio susceptibility. “AVP+” control compares favorably among the three schemes.
	Construction of FPGA based Hardware Controller for Autonomous Decentralized Control for UPS Application   By Wataru Fujii, Tomoki Yokoyama	[View]   [Download]
Abstract: Design concept of FPGA based hardware controller is proposed with basic modules for the development of power electronics applications. Also an autonomous decentralized control system for single phase UPS inverter with FPGA based hardware controller using software CPU core is described. Progress of FPGA technology makes it possible to include the software macro CPU core into the FPGA chip, a high flexibility can be realized for the construction of the control processor in power electronics application. But the basic modules for power electronics application are not enough in the environment of FPGA development platform. In this paper, several modules are presented for power electronics applications, and also proposed an autonomous distributed control system for single phase UPS inverter with FPGA based hardware controller using CPU core. The advantages of FPGA based hardware control system are discussed.
	Contribution to the Reference Voltage Form of Frequency Inverters   By Jiri Pavelka, Petr Pavelka	[View]   [Download]
Abstract: An AC voltage or current supply having the sinusoidal waveform is the task of most frequency converters. PWM methods of the modulation are used in majority of cases. These methods require forming reference signals for realization of a switching strategy. This contribution deals with to the analysis of possibilities to form a reference signal for the output sinusoidal quantity.
	Control Issues of a ZCS Inverter   By Vincenzo Delli Colli, Roberto Di Stefano, Fabrizio Marignetti, Maurizio Scarano	[View]   [Download]
Abstract: The Ishikawa and Murai zero current switching inverter offers promising charcteristic for several applications. Nevertheless, to date the control issue was not yet fully addressed. The paper reviws the converter evidencing the nonlinearity, the loader-filter resonance issue, and the resonant time duration. An equation for the forecasting of the resonant times is checked. Consequently, a modulator is proposed and described in detail, then verified experimentally. This paper finally proposes and verifies a vector control with active damping. An active damping control structure is defined, tuned and verified by means of experimental tests taking into account serveral versions. Although this work does not fully address the control issue it evidences the control requirements of the converter and it is helpful in the converter evaluation and application.
	Development of an Optimal Fuzzy Controller for Novel Power Architectures in Automotive Applications   By Andres A. Nogueiras, Oscar Lopez, Luis J. Alvarez, Alfonso Lago, Jesus Doval, Jorge Marcos, Carlos Martínez-Penalver	[View]   [Download]
Abstract: The design of synchronous multiphase DC-DC converters allows improvements of the characteristics of high power systems. The automotive industry forecast that future power demands inside a car will oscillate between 2.5 kW and 3.5kW, keeping a dual system of 42/14V batteries. In this paper, an optimal fuzzy controller has been developed to control a synchronous multiphase converter of 1.6kW for dual voltage architecture or in hybrid vehicle applications. The proposed optimal fuzzy controller is analyzed and simulated together with a non lineal model of the power stage, by means of Matlab and Simulink. This simulation platform also integrates tools for a future implementation of the controller embedded in a FPGA. The main contribution of this work is the implementation of an optimal fuzzy algorithm of control that can be used independently of the number of phases of the converter, making it suitable to be applied in a wide range of high power applications. This controller has been designed having in mind the goal of developing a real-time FPGA-based controller, so the complexity has been reduced to a minimum. Hybrid vehicles, aerospace and naval industry power systems can also benefit from the development of this algorithm.
	Digital Control of Two Stage High Power Inverter   By Otu A. Eno, David S. Thompson	[View]   [Download]
Abstract: With increasing demands worldwide for more electrical energy and the desire to reduce greenhouse-gas emissions, increasing attention is directed at sources of renewable energy, such as photovoltaic and wind, the development of clean distributed generation becomes increasingly important. The electrical output from such sources is small and dc. Coupling such outputs to a constant voltage and frequency grid requires two stages of energy conversion: dc-dc and dc-ac. As small-scale inverters tend to have lower efficiency than larger inverters, it is important to optimize the control circuits and to choose a topology with the lowest possible power dissipation, if they are to compete with larger scale converters. This contribution focuses on such a system and its overall control for the efficient and reliable injection of energy into a grid.
	Digital Resistive Current Control for the Parallel Interleaved DC-DC Converters   By Hyun Su Bae, Jae Ho Lee, Bo Hyung Cho	[View]   [Download]
Abstract: In this paper, a digital resistive current (DRC) control for parallel interleaved DC-DC converters is proposed. Converting the effective input characteristic of the converters seen by the source as a resistive load sink for current sharing, the proposed control scheme achieves current mode control, like the conventional analog charge current mode control. Also, the sub-harmonic oscillation at the light load is defined and the method to avoid this problem is presented. Thus, using this control method, it is possible to use the converters operated in continuous conduction mode (CCM) and discontinuous conduction mode (DCM). The complete small signal model with the digital sampling effect is developed to perform the stability analysis and the design guideline. For the design example, two 100W parallel module buck converters with a TMS320F2812 DSP has been built and tested by using the proposed DCR control.
	Digital Variable Frequency Control for Zero Voltage Switching and Interleaving of Synchronous Buck Converters   By Pal Andreassen, Giuseppe Guidi, Tore Undeland	[View]   [Download]
Abstract: When a synchronous buck converter is operated with zero voltage switching (ZVS) and fixed frequency, the direction of the current in the output inductor is alternated each switching period. Thus the output current ripple of the converter is high to ensure zero voltage switching operation at maximum load. With interleaved outputs this leads to high circulating currents at low loads. In this paper, to minimize circulating currents at low loads, solutions for digital control of ZVS with variable switching frequency and interleaving control for bidirectional power flow are presented. The methods have been implemented in a DSP and verified by measurements.
	Fast Current Control of Three-Phase PWM Converter for Rectangular-Waveform Distribution System   By Hitomi Matsue, Takaharu Takeshita	[View]   [Download]
Abstract: This paper presents the input current control scheme of three-phase PWM converters to realize the unity effective power factor and the stable output dc voltage for the rectangular-waveform distribution system. The input current control is based on the discrete-time system. The authors propose the fast control scheme of the input current under the voltage saturation of the PWM converter. The effectiveness of the proposed current control scheme has been verified by experiments.
	Feedback Control of the Three-Level PWM Rectifier: Application to the Stabilisation of the DC Voltages of a Multilevel Inverter   By Farid Bouchafaa, El-Madjid Berkouk, Mohamed Seghir Boucherit, Bruno Francois	[View]   [Download]
Abstract: A serious constraint in a multilevel inverter is the capacitor voltage-balancing. In order to stabilize these DC voltages, we propose to study the cascade constituted by a three phase three-level PWM rectifier, a clamping bridge and a nine level NPC voltage source inverter (VSI). In the first part, the authors present the topology of the nine-level NPC and they propose a model of this converter and the algebraic PWM strategy to control it. Then in the second part, we study the three-level PWM rectifier, which is controlled by a hysteresis strategy. In the last part of this paper, the authors study the stability problem of the input DC voltages of the inverter. Clamping bridges are used to control each DC capacitor voltage. To control the full DC bus voltage a closed loop control is implemented inside the control system of the rectifier. The obtained results are full of promise to use the inverter in high voltage and great power applications as for electrical traction.
	Fixed Frequency Sliding Mode Control for Boost Converter   By Maurice Fadel, Ana Maria Llor	[View]   [Download]
Abstract: This paper describes a sliding mode controller for a boost converter in fixed-frequency operating mode. The control law is built in using a Lyapunov function in order to minimize the energy storage for transient operation. The switching function uses a load observer and is implanted according to a constant frequency scheme. The article notes several tests in numerical simulation.
	Flux Balance Assurance in Output Transformers of Sine-Wave Inverters using DC Autonulling Control Principle   By Henrik Lavric, Rastko Fiser	[View]   [Download]
Abstract: A new approach for flux imbalance prevention is proposed in this paper. The basic idea is to suppress DC component of the transformer primary voltage using the closed control loop around the hybrid amplifier with the first order low-pass filter and the integrator in the feedback path. The operation of proposed scheme is analyzed in detail analytically and by means of computer simulations. Experimental results are in accordance with simulations and confirm the suitability of the cost effective solution.
	FPGA based Discrete Event Current Control Strategy for a Three Phase Inverter   By Ales Polic, Karel Jezernik	[View]   [Download]
Abstract: This paper investigates the possibilities of the design of current control for VSI from the discrete event point of view. Event-driven control approach determines the transistor switching pattern directly from the current error logic signals and is designed using a novel matrix based approach for the description of the discrete event systems. A new approach for description of event-driven systems is introduced. It is based on matrix description of Petri Nets, supplemented with a combination of logic and algebraic equations. The control algorithms designed by proposed approach can be easily implemented on modern DSP an FPGA devices. The approach is illustrated with the design of direct current controller for a three phase inverter fed Permanent Magnet Synchronous Machine and is examined with simulations and experimentally confirmed.
	Hysteresis Regulator with Clocked Commutation in DC/AC Power Converter System   By Yury Kolokolov, Stanislav Koschinsky, Dmitry Tey, Janan Zaytoon, Abdelaziz Hamzaoui	[View]   [Download]
Abstract: Research of hysteresis regulators with clocked commutation in dc/ac converters is presented. Method of hysteresis calculation is offered to improve regulation accuracy of hysteresis regulators with clocked commutation in dc/ac voltage convectors.
	Improvement Signal Output of DM-PWM Inverter for Driving High Efficient Electrical Load   By Pinit Thepsatorn, Chalong Sodaban, Vittaya Tipsuwanporn, Pongsak Jitnaknan	[View]   [Download]
Abstract: This paper is shows technique of improvement signal output of inverter for driving high efficient achieve of improvement is designed by pulse width modulation which is delta modulation in order to use simply method and is not difficult, However, this method achieves high efficient output signal that dives slightly lower percent of harmonic. There more, Signal of output produces obtained heavy sinusoidal and declined dramatically by EMC. In addition, this new method is able to drive static and dynamic load which are not only single phase but also three phases.
	Model Reference Adaptive Control of Asynchronized Synchronous Motor based on Neural Network On-Line Identification   By Li Liu, Xiaoqiong He, Jian Xiao, Helmut Weiss	[View]   [Download]
Abstract: From system control point of view, asynchronized synchronous motor is a complex nonlinear plant with uncertainties, and is hard to be controlled by traditional control method. An excitation control method based on model reference adaptive control of asynchronized synchronous motor using neural network on-line identification is proposed in this paper. This method utilizes the mapping abilities of neural networks to construct the reference model of the plant, and self-learning is achieved by means of neuron. The simulation results show a better robustness and control accuracy of the proposed method.
	Modeling and Control of a Power Electronic Cascade for the Multi DC Bus Supply of a Seven-Level NPC Voltage Source Inverter   By Abdelaziz Talha, El-Madjid Berkouk, Bruno Francois, Mohamed Seghir Boucherit	[View]   [Download]
Abstract: The stability problem of the input DC voltages in a seven-level Neutral Point Clamping (NPC) Voltage Source Inverter (VSI) is recalled and illustrated. A first solution involving six controlled-voltage (CV) rectifiers is presented. A knowledge model of this converter using switching functions and a PWM strategy is detailed. For an economic point of view, a second power structure is proposed. It consists in using only 3 CV rectifiers but the instability of intermediary DC voltages is observed. To solve this problem the power structure is modified by adding clamping bridges across capacitors in order to limit their deviations. Additional control functions are then introduced. The obtained results are full of promise to be used to stabilise the input DC voltages of these converters.
	Multicarrier PWM with DC-Link Ripple Feedforward for Multilevel Inverters   By Samir Kouro, Mauricio Angulo, Jose Rodriguez, Jorge Pontt	[View]   [Download]
Abstract: Multilevel inverters have become an attractive alternative for medium voltage and power quality demanding applications. However, like most power converter families, multilevel inverters are controlled with modulation techniques that are conceptually based on nonlinear waveform synthesis assuming constant dc-link voltages. Nevertheless, real applications have load and supply dependent dc-links that usually present important low frequency ripple. Due to the high switching frequency operation of the converter and the low-pass nature of the loads, the dc-link ripple is also modulated and transmitted to the load, generating undesired low frequency voltage and current distortion. This can be critical in high power applications due to the amount of energy involved in these harmonics. This paper introduces a simple but effective dc-link ripple feedforward strategy into traditional carrier-based modulation techniques, which eliminates the undesired harmonics. Experimental results show the accuracy of the proposed method, which is specially useful for open loop applications.
	On-Line Electrical Quality Improvement of a Single Phase Boost Rectifier with Fuzzy Controller and Experimental Designs   By Jerome Faucher, Pascal Maussion	[View]   [Download]
Abstract: In this paper, experimental design methodology is used for the on-line tuning of a fuzzy controller dedicated to electrical engineering applications with multi-objective criteria. Our purpose is to improve the input and output system characteristics as well as the quality of electrical power. The desirability notion combines here time dynamic and harmonic criteria for a boost rectifier with unity power factor correction and illustrates the trade-off that has to be made between the different properties.
	Optimized Resonant Control for Shunt Active Power Filters   By Antonio Dell Aquila, Maria Marinelli, Vito Giuseppe Monopoli, Agostino Lecci	[View]   [Download]
Abstract: This paper presents an optimization technique of the resonant controller based on the minimization of an objective function through the Nelder-Mead method. This function allows to evaluate the behavior of the system in steady state and transient conditions. The optimized controller has been compared with the Naslin polynomial based one. The results show that by means of the optimization technique it is possible to achieve better performances also in presence of harmonics the control system has not been designed for.
	Predictive Current Control Strategy with Imposed Load Current Spectrum   By Patricio Cortes, Jose Rodriguez, Daniel Quevedo, Cesar Silva	[View]   [Download]
Abstract: A modified predictive current control strategy is presented in order to have control over the spectrum of the load current. The proposed strategy uses a model of the system to predict the behavior of the current for each possible voltage vector generated by the inverter. For that purpose, at each sampling interval, signal predictions are evaluated using a cost function that quantifies the desired system behavior. The cost function used in this work evaluates the filtered error of the load currents. The inclusion of a filter for the load error allows one to manipulate current spectra. Thus, by designing this filter appropriately, the load spectrum can be shaped.
	Predictive Digital Interpolation Current Control   By Carlos Eduardo Carrejo, Enric Vidal-Idiarte, Roberto Giral, Luis Martinez-Salamero	[View]   [Download]
Abstract: The design of a totally digital current control of a dc-dc switching converter has been analysed in this paper. This control consist of the prediction of the time when current inductor will reach the current inductor reference. This prediction has been obtained by means two samples of real inductor current and the application of the general equation of a straight line. This Predictive Digital Interpolation strategy has the same philosophy is classical analogy current control method and also maintain their dynamic characteristic.
	Robust Predictive Dead-Beat Controller for Buck Converters   By Joerg Weigold, Michael Braun	[View]   [Download]
Abstract: This paper presents a predictive dead-beat current controller which uses an online estimation of the system’s behavior. Only the measurement of inductor current is necessary for the realization. This idea also works for variable parameters of the load and of the power supply as well. Here pulse width modulation (PWM) method with constant frequency is taken into use, to limit switching losses. After a setpoint step-change, a new switch duty cycle is computed. If possible, the new setpoint is reached after one pulse period. That means, after the setpoint step-change, it takes one pulse period for the calculation and one more period to reach the final value.
	Sensorless Control of a Grid-Connected PV Converter   By Istvan Varjasi, Attila Balogh, Sandor Halasz	[View]   [Download]
Abstract: The base of our new developed grid-connected PV converter is a low cost general purpose frequency converter. In spite of the lack of voltage sensors a very reliable antiisland protection is reached. In the first section a control structures of the grid-connected converter with UVOC (Utility Voltage Oriented Control) is given while in the second section a method for the sensorless identification of the grid voltage is suggested. The third section describes an ultimate method for anti-island protection with a negligible none-detection zone. Finally the experimental results of the developed low cost general purpose frequency converter are presented.
	Simple Control Algorithm to Balance the DC-Link Voltage in Multilevel Four-Leg Four-Wire Diode Clamped Converters   By Jose I. Leon, Giuseppe Guidi, Leopoldo G. Franquelo, Tore Undeland, Sergio Vazquez	[View]   [Download]
Abstract: Multilevel converters and specially multilevel four-leg four-wire converters actually are an important focus of researchers. Applications as harmonic compensation and energy quality are the major objectives of this type of converters. The balancing of the DC-Link capacitors voltage is a critical problem in multilevel converters and the first control strategy based on using the redundant vectors in a Space Vector Modulation scheme for four-leg four-wire Diode Clamped converters is presented. The balancing algorithm was simulated and finally successfully implemented in a real prototype. It is important to notice that the proposed method is completely generalized an due to it, it is independent of the load and independent of the number of levels of the converter. Besides, the proposed balancing control algorithm works with balanced or unbalanced loads. Experimental results are presented using a 50KW prototype.
	Snubbers in the Three-Phase AC to DC Buck Converter   By Franc Mihalic, Dejan Kos, Miran Rodic, Miro Milanovic	[View]   [Download]
Abstract: In this paper, investigation of effective snubber circuits in the three-phase AC to DC buck converter is presented. Based on the theoretical analysis and from the conventional matrix converters theory approach, the mathematical proof for an AC to DC power converter with unity input displacement factor (IDF) operation without current sensing, is provided. For the DC output current bulky inductance in the output filter is needed and appropriate modulation strategy without open circuit terminals must be assured. High inductance and very short switching times of the power switches are main source of the high and destroying dv/dt in the power converter. This problem can be overcome by proper driving circuits and by appropriate design of the effective snubber circuits not only at the switching power transistors but also at the series diodes as well. And finally, all theoretical considerations are verified by digital simulations and measurements on a low-power prototype of a three-phase buck rectifier.
	Space Vector PWM for a Five-Phase VSI Supplying Two Five-Phase Series-Connected Machines   By Atif Iqbal, Emil Levi	[View]   [Download]
Abstract: A five-phase two-motor drive system with series connection of stator windings and decoupled dynamic control has been introduced recently. The two-motor drive system is supplied from a single five-phase voltage source inverter (VSI) and controlled using vector control scheme. If current control is to be implemented in the rotating reference frame, a PWM method for the five-phase VSI is required to generate required voltages. This paper proposes a scheme to generate inverter output voltages using space vector PWM, in such a way that independent control of two five-phase series-connected machines is achieved with a minimum interaction between the two machines. The method generates output voltages that contain only two lowfrequency fundamentals at operating frequencies required by the two machines. The concept is verified by simulation.
	Stability Analysis of PWM-Controlled Dual Channel Resonant Buck&Boost Converter using PI Controller   By Balazs Buti, Istvan Nagy, Eisuke Masada	[View]   [Download]
Abstract: The paper is concerned with the stability analysis of a feedback controlled resonant dual channel buck&boost converter. The output voltage is controlled by using constant frequency PWM and PI controller. The analysis is based on the eigenvalues of the Jacobian matrix of the Poincaré Map Function (PMF). After small perturbation determining the deviations of the state variables from the periodic trajectory, the Jacobian matrix is calculated without the need to determine the PMF itself. The introduction of the so-called auxiliary state vector greatly facilitates the calculation. Calculation and simulation results included helps the design of the control loop.
	Synchronous Control of Cascaded Three-Level Inverters   By Valentin Oleschuk, Francesco Profumo, Alberto Tenconi, Alexandar Stankovic	[View]   [Download]
Abstract: Novel method of synchronous pulsewidth modulation (PWM) has been disseminated for control of cascaded neutral-point-clamped inverters feeding open-end winding induction motor drive with single dc voltage source. Control algorithms provide in this case full elimination of the common-mode voltages both in each inverter and in the load. Phase voltages of the drive system are characterised by quarter-wave symmetry during the whole control range including the zone of overmodulation, and its spectra do not contain even harmonics and sub-harmonics (combined harmonics). Simulations give the behaviour of the proposed methods of synchronous PWM in these systems. Continuous, discontinuous and “direct-direct” schemes of synchronous PWM, applied for control of cascaded threelevel converters, have been analysed and compared.
	Utilization of Low Distortion Power Electronics Current Sources in Generator of Spatial Magnetic Field   By Michal Gwozdz, Ryszard Porada	[View]   [Download]
Abstract: The paper considers Generator of the Spatial Magnetic Field for medicine purposes. One of essential blocks there is three-channel power electronics current source, powering set of space oriented induction coils (electromagnets) – sources of magnetic field. The control module utilizes DSP based microcomputer for power electronics applications. The microcomputer is integrated with industrial PC in form of PCI card. The execution block utilizes three power electronics inverters, utilizing PWM strategy. The paper describes fundamentals of current source control algorithms and test results of laboratory model of generator.
	Voltage Balance Control for a Multilevel Interface for Renewable Energy Systems   By Edward Christopher, Mark Sumner	[View]   [Download]
Abstract: This paper presents a new method to balance the DC link voltages in a 3 level Diode Clamped Rectifier, even in the presence of unbalanced loads which cause a non-zero neutral point current. The method employs an offset which is added to each of the inverter modulation waves. This offset causes a zero sequence voltage which can drive the desired neutral point current whilst maintaining balanced DC link voltages. Simulation and experimental results confirm the method.
	ZCS Predictive Controllers for High Frequency AC-Link Resonant Converter   By Maurizio Catucci, Jon C. Clare, Patrick W. Wheeler	[View]   [Download]
Abstract: This paper focuses on new control techniques for a direct power converter having a resonant tank on the output side feeding a rectifier. The application being considered is for HV power supplies. The objective of the control is to provide a stable output, with good supply current quality. Two predictive controllers are described, one based on the output tank dynamics and one based on the input filter dynamics, and their performances are compared. Practical results from a laboratory prototype are presented.