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EPE-PEMC 2002 - Topic 03: Control of Converters
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	A Fuzzy Current Control for Three-Phase Four-Wire Shunt Active Filters   By A. Dell'Aquila; A. Lecci	[View]   [Download]
Abstract: The aim of this work is the introduction of a fuzzy current control for a three-phase four-wire shunt active filter. Proposed control is able to ensure a proper reduction of current tracking error while allowing a fixed frequency switching operation of the inverter legs. The effectiveness of this shunt active filter is proved in simulation where the pollution produced by a non-linear load has been drastically compensated. Good results have been achieved in reactive power compensation and neutral current reduction too.
	A Hysteresis Modulation Technique for NPC Inverters in Digitally Controlled Induction Motor Drives   By A. Bellini; S. Bifaretti; S. Costantini	[View]   [Download]
Abstract: The recent development of the new power transistor generation has led to the realization of High Voltage/High Current IGBTs, which allow the electric power management with higher commutation speed. Therefore, IGBTs have been progressively replacing GTO devices in low and medium voltage inverters used in trams or regional trains and now they are also becoming attractive for modern locomotives. Nevertheless the maximum voltage supported by the actually available IGBTs doesn’t yet permit the employment of two-level VSI in high-speed or heavy traction drives applications; so, to take advantage of IGBTs characteristics, Neutral Point Clamped inverters must be used. The paper analyzes the peculiarities of the previously developed hysteresis modulation techniques for NPC inverters and suggests a suitable improvement. The proposed technique keeps the advantages of simplest hysteresis controls, i.e. fast response, good accuracy, no need to know load parameters; in addition, the modulator can be easily implemented if the microcontroller performs the error zone computation and a Programmable Logic Device provides the inverter control signals.
	A New Modulation Method to Reduce Common-Mode Voltages in Multilevel Inverters   By J. Pontt; J. Rodríguez; P. Correa	[View]   [Download]
Abstract: This paper proposes a new modulation strategy for multilevel inverters, which selects voltage vectors that generate zero common-mode voltage in the load, working at low switching frequency. Experimental results confirm that the method is highly effective and simple to implement in a modern microprocessor. The voltage distortion (THD), the number of commutations and the linearity are also studied. Finally, it is concluded that the proposed strategy is highly suited for inverters with a high number of levels.
	A Novel Control Concept for Highest Precision Accelerator Power Supplies   By F. Jenni; M. Horvat; L. Tanner	[View]   [Download]
Abstract: Accelerator applications need extremely precise power supplies (PS) for their various magnets. For the control an exact modelling of the PS and the load is essential. A sophisticated analog to digital conversion scheme is the key part for the necessary precision. A fully digital controller enabled identical control hard- and software for 580 units, allowing high flexibility of the control structures. Adaptions for different types of PS are made by software parameter adjustments only.
	A voltage sag detection algorithm based on rectified voltage processing   By A. Mariscotti; M. Mazzucchelli; R. Chiumeo; A. Florio	[View]   [Download]
Abstract: An algorithm for voltage sag detection, based on the processing of the rectified voltage waveform, is presented and its performances are evaluated by means of artificial voltage/current signals, recorded voltage waveforms (at some MV/LV transformers) and simulated voltage/current waveforms (using ATP circuit simulator). The algorithm is intended to detect voltage sag occurrence and to trigger the disconnection of the faulty supply network and subsequently the connection of the voltage support system. In the actual implementation the voltage support system is composed of a Voltage Source Inverter connected to the MV busbar by a coupling transformer with filter bank and supplied by a Superconductive Magnetic Energy Storage (SMES) system.
	Analysis of Energy Converters for DC and AC Supply Sources Operated from an Accumulator Plant on Field   By J. Borka; M. Horvath	[View]   [Download]
Abstract: The aim of the work is to substitute the traditional rotary machine equipment driven by environment-polluting, internal combustion engine on field with an up-to date, energy-saving, environment-friendly electronic DC and AC supply source operated from an accumulator plant. This solution serves for supplying both the DC compact welding equipment and the AC electric hand tools of 230 V, 50/60 Hz.
	Analysis of Flux and Torque Control Improvement of AC Motor Controlled by DTC Method   By A. Sikorski; M. Korzeniewski	[View]   [Download]
Abstract: Method of interpretation of flux and stator current distortion for small rotor angular velocity of AC motor controlled by DTC method is presented in paper. Correctness such analyse was confirmed by simulation and experimental results.
	Bandwidth and maximum switching frequency of multicell converters   By R. Ameur; T. Meynard; M. Fadel	[View]   [Download]
Abstract: In this paper, the authors focus on the evaluation of the bandwidth of the series multicell converter. A method to determine the theoretical limit of the operational frequency is presented. Several control laws using a constant switching frequency are proposed and compared. The final aim is to realize a control law which has the maximum bandwith.
	Compensation of Buck PWM Rectifier Input Current Harmonics Caused by Distorted Line Voltages   By J. Matulka; J. Ribkowski; R. Barlik; M. Nowak	[View]   [Download]
Abstract: The paper discusses certain aspects of the PWM line current type rectifier control. The capacitors present on the line side together with line and input chokes inductance create an oscillating circuit. Its second order transfer function gains current harmonics existing in the supply line voltage – specially those which are close to filter resonant frequency. In previous papers methods of damping of the excited oscillations has been proposed but if the line voltage contains harmonics the input current also has to be distorted respectively to LC filter transfer function. The control method proposed in the paper, designed for line PWM buck converter, ensures elimination of low order line current harmonics caused by voltage distortion. The results obtained by simulations confirm positive features of the method with regard to one and three-phase converters. Laboratory investigations done with an IGBT 10 kVA three phase converter also gave positive results respective to the high dynamic control structure implemented in DSP.
	Control of a Three Phase Inverter Feeding an Unbalanced Load and Operating in Parallel with Other Power Sources   By M. Hauck; H. Späth	[View]   [Download]
Abstract: A control for a three phase inverter, acting as a voltage source, is presented. The inverter is able to work in parallel with a constant-voltage constant-frequency system, as well as with other inverters or also in standalone. There’s no communication interface needed. The different power sources can share the load also under unbalanced conditions. To achieve this the frequency and the amplitude of the grid voltage can have small variations. By introducing a secondary control load sharing is even possible without frequency or amplitude deviations in steady-state. Measurements are presented to prove the good control behaviour.
	Control Of AC-DC Line Frequency Resonant Converter   By T. Vinnal; J. Järvik; K. Janson	[View]   [Download]
Abstract: The ac-dc line frequency resonant converter with parametric alternating of parallel and series resonant mode (PSA converter) have high power factor and efficiency. Still the current control of PSA converter from nominal to zero is a specific problem. The control is achieved, where together with phase control of inductive circuit of converter the current of capacitive circuit is by-passed from the rectifier with the help of additional thyristors. By control correction of power factor is also possible.
	DC-DC Converter With Intelligent Power Module Safety Operation Problems Of IPM   By A. Pracownik; S. Kosiorowski; M. Tondos	[View]   [Download]
Abstract: Protection against damage states in a dc-dc converter with an Intelligent Power Module has been the main goal of the described investigations. These works concern both elimination of adverse impacts of IGBT transistor capacitance links on the converter control system and protection of IPM module during short circuit in an external load.
	Development of Embedded Control based on Simulation   By P. Bauer; P. J. Van Duijsen	[View]   [Download]
Abstract: Embedded control is in Power Electronic systems and electrical drives still more and more replacing the traditional electronic controls. The design of embedded controls usually takes place in a development environment programming the microprocessor, micro controller or DSP. Important in the design of embedded controls is the interaction with the controllable power electronics. Therefore a combination between the program development environment and the Power Electronics simulator is required. Ability to simulate the power converter circuit and at the same time to step with a debugger through the programming embedded control source code is hereby offered. In the paper such a development of embedded control with the help of a simulator is described.
	Experimental Investigation of Overmodulation Region of Inverter-Fed Ac Drives   By A. Zacharov; I. Varjasi; S. Halász	[View]   [Download]
Abstract: The results of theoretical investigation of the overmodulation strategies are presented and used for the practical evaluation of the overmodulation control region of inverter-fed ac drives. Different PWM strategies (space vector and two-phase or Flat-Top modulations) are realized by DSP control and are experimentally investigated. Special consideration was taken to maintain the effect of switching delays and dead time negligible. It was shown that asynchronous modulation together with overmodulation causes significant torque fluctuation even if the frequency ratio is above one hundred.
	FPGA-Based Modulator for Five-Level Inverter Control using Pulse Patterns for Harmonic Elimination   By E. Weigand; D. Hasenkopf; J. Xie	[View]   [Download]
Abstract: In this article, a modulator implementation for the control of a voltage-source inverter with computed pulse patterns is described. The pulse patterns can be computed using the harmonic elimination approach. The time critical sections of the modulator functionality are implemented using programmable logic devices (PLD), which are very similar to field programmable gate arrays (FPGA). Via a PC bus interface, the PLD is connected to a host processor, which performs the higher level control tasks. The inverter is built up from three identical phase-modules. Each phase-module consists of a full-bridge-circuit in three-level topology, and therefore has five different output voltage levels per phase. With this inverter, diffirent control methods for active balancing of railway traction power supplies are investigated.
	Generalised Voltage Control For A Multi-Purpose Switchng Mode Converter   By D. V. Nicolae; M. J. Case	[View]   [Download]
Abstract: In this paper, a single-phase switching mode converter acting as a unity power factor rectifier and/or as active power filter with no alteration in the topology is studied. A generalized voltage control taking in consideration the output power of the DC bus is developed. To demonstrate the improved response of the voltage regulator, a battery charger as “unknown dc load” is used.
	H. Control of a Bi-Directional Flyback Power Converter   By W. E. Bury; S. Ramamurthy; S. Lewis; J. Dzieza; D. Czarkowski	[View]   [Download]
Abstract: A bi-directional flyback converter utilizing an H-inf controller for tracking was designed and tested. The H-inf controller was reduced from a 3rd to a 2nd order function with a theoretical limitation of 10 kHz. This paper presents the experimental and theoretical results for the controller autonomously and in a closed loop
	High quality voltage source using a multi-converter strategy   By N. Ginot; J.-C. Le Claire	[View]   [Download]
Abstract: As often as not, the multilevel converters are used in order to increase the output power [1]. Here we propose a way for paralleling the inverters. So, this paper deals with both converters whose one of them acts as a slave current power source, and the other acts as a voltage master source. The slave current controlled converter feeds the power to the load when the voltage controlled converter is in charge of the voltage reference tracking. Therefore, by combining some converters, it is possible to share out the output power, when a single inverter uses a high frequency switching and accurately tracks the reference. The next synoptic (fig 1) illustrates such a structure.
	Hysteresis Current Regulation for the Field-Oriented-Controlled Induction Motor Drives with Matrix Converter   By V. Perelmuter	[View]   [Download]
Abstract: In this paper regulation of the field-oriented components of the induction motor (IM) stator current vector is investigated. It is supposed that IM is fed from a matrix converter. Hysteresis current regulation is performed in the rotating reference frame. A new control method of the displacement angle between the input line-to-neutral voltage vector and the corresponding input current vector is proposed that in comparison with the conventional method gives an opportunity, with using of a simpler algorithm, to improve the IM utilization together with reducing of the commutation frequency. For algorithm different modifications analytical relations are received for computation of the system main characteristics. The problems of input current filtration, that are very urgent in this class of converters, are investigated too. The simulation that illustrate the operation of the proposed system and its comparison with the other known schemes is presented.
	Investigation of a Current Controller in Synchronous Reference Frames for Inverter-Based Active Balancing of Single-Phase Railway Loads   By D. Hasenkopf; J. Xie	[View]   [Download]
Abstract: Railway traction power supply systems are fed directly from the public three-phase grid, if both operate at the same frequency. These railway substations are high power single-phase loads. This paper discusses a controller working in synchronous reference frames for a shunt inverter used for active balancing of the single-phase loads.
	Low Switching Frequency PWM with Selective Harmonic Elimination for Three-Phase Three-Level Inverters   By J. Pontt; J. Rodriguez; R. Benavides; M. Müller; R. De Solminihac	[View]   [Download]
Abstract: Low Switching Frequency Modulation with Harmonic Elimination for Three-Level Inverters reduces harmonic distortion at the Three-Phase load, EMI emissions and thermal stress in power switches. The calculation algorithm for the 3-, 5-, and 7-Angle-Scheme and the remaining harmonics up to the order 31 are presented. Experimental and simulated results verifies the expectations.
	Microprocessor - Based PWM Inverter   By M. Tondos; A. Stobiecki; P. Michalak	[View]   [Download]
Abstract: The paper presents a three-phase, voltage source inverter designed for supplying induction motors of several kilowatts rated power. The basic component of the inverter power circuit is an intelligent power module PM15RSH120 of the Mitsubishi Electric manufacture, comprising seven IGBT transistors with gate drivers and protection system in an insulated package. The inverter control system with Intel 8051 microcontroller used as a supervisory controller and MA828-1 GEC Plessey Semiconductors PWM generator employed for three-phase voltage waveform generation has been described. Additional inverter protection systems and selected results of laboratory tests have been presented.
	Modeling and Control of a Three-Phase Neutral-Point-Clamped Inverter by Means of a Direct Space Vector Control of Line to Line Voltages   By B. François; E. Semail	[View]   [Download]
Abstract: This paper presents a modulation strategy that enables to copy directly modulated waveform onto output voltages of a three-phase N.P.C. inverter. A particular modeling of this converter is presented. The feasibility of a space vector scheme without using a Park transform is studied. All voltage vectors are drawn into the line to line voltage frame. Then three voltage vectors are selected for the modulation and simultaneously their durations are calculated. The effect of the modulation on the capacitor divider is studied and a balancing strategy is deduced.
	PC-based control hardware for 200-kW double three-level converter   By V. Staudt; A. Steimel; M. Kail	[View]   [Download]
Abstract: A digital control system based on generic x86 PC components was implemented in order to develop and evaluate control algorithms for high power active front ends (AFE) in the megawatt range on a scaled-down 200-kW test bench. In this paper the overall converter-system and its requirements to the digital control are described. A high performance / low cost target hardware for digital control is proposed that offers a reasonable alternative to powerful comercially available DSP systems. The crucial necessities for using a PC system as a reliable real-time platform are pointed out and several tests of the control hardware are proposed. Their results are presented and discussed with respect to the suitability of the PC-system for hard realtime control. While most features of DSP systems are already implemented, aspects for improvement and drawbacks of the proposed system are pointed out as well.
	Reference Harmonics Reduction Method for Utility Tie Converter with Digital Controller   By H. Shiraishi; E. Masada; M. Ohshima; K. Shutoh; J. Baba	[View]   [Download]
Abstract: Reference harmonics reduction method is proposed. For reference harmonic reduction method, first-order hold or second-order hold are proposed and designing method are proposed and discussed to reduce harmonics generated by a digital controller owing to the difference between current controlling period and reference generation period when a converter with high current control performance is used.
	Special Operating Conditions and Control Procedures of Energy Converters for Half-Wave X-ray Equipment   By J. Borka; M. Horvath	[View]   [Download]
Abstract: Up-to-date X-ray equipment cannot be realised without applying modern power electronic energy converters, e.g., high frequency inverters, network-friendly converters, etc. The anode supply unit of the X-ray equipment operates in special loading conditions and requires a special control procedure. The realisation of optimal supply conditions (modulation method, energy transfer and switching frequency, etc.) of the anode transformer with significant winding capacitance and stray inductance in high voltage X-ray equipment is an important problem in practice and is interesting from theoretical viewpoints, as well. These problems have been formed the substantial parts of R&D work.
	Spice Dynamic Macromodel of PWM Controller with Selfheating Taken Into Account   By J. Zarebski; K. Górecki	[View]   [Download]
Abstract: The paper presents the problem of electrothermal modelling of PWM controllers for SPICE, including the selfheating phenomenon. A new form of the electrothermal macromodel of SG3525A controller consisting of three blocks representing the electrical model along with the parameters dependent on temperature, the thermal model and the model of the real power dissipated in the considered device, is proposed. The macromodel was implemented to SPICE and to illustrate its correctness and usefulness some analysis and measurements of the electrothermal performances of SG3525A controller, operating both in the catalogue test circuit and in the boost converter, have been carried out. As it is seen from the presented results selfheating affects strongly some parameters and characteristics of the investigated controller.
	Triphase Cascaded Converters with Direct Synchronous Pulsewidth Modulation   By V. Oleschuk; B. K. Bose; F. Blaabjerg	[View]   [Download]
Abstract: A novel method of direct synchronous pulsewidth modulation (PWM) is applied for control of modular multilevel converters consisting from three standard triphase inverter modules along with an 0.33 p.u. output transformer. The proposed method provides synchronisation of the voltage waveforms for both each module and the composed voltage at the output of the converter. Multilevel output voltage of the converter has quarter-wave symmetry during the whole range including the zone of overmodulation. Both continuous and discontinuous versions of synchronous PWM, based on a vector approach for determination of the pulse patterns, have been analysed and compared using simulations of the systems with low switching frequencies, which normally are used in high power systems.
	Use of Resonance in the Control of a Current Source Rectifier   By X. Guillaud; J. F. Glowacka; P. Degobert	[View]   [Download]
Abstract: Pulse width modulated current source rectifiers find their application in current source power converters . For this type of rectifier, special attention has to be given for the starting of the current source and an appropriated control algorithm is needed. We propose a rigorous method for the modelling of the process and the design of the appropriate control algorithm. The LC filter placed between the voltage generator and the converter is very sensitive to the effect of voltage harmonic disturbances. We present an application of multiresonant controller to improve the spectral analysis of the line current.