Special Section on PWM Converter Current Control .... research and theoretical work on electrical drive control and industrial electronics. He is the author or coauthor of over 90 technical papers and reports, as well as 11 books and textbooks.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 45, NO. 5, OCTOBER 1998
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Guest Editorial Special Section on PWM Converter Current Control
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HERE IS NOW a general preference in ac/dc and dc/ac conversion to use voltage-source (VS) rather than currentsource (CS) converters. This trend, which grew in the last two decades, is mainly justified by the introduction of power devices with turn-off capability and by the advantages of a capacitive dc storage, over an inductive one, in terms of weight, cost, and efficiency. Additional advantages include the facts that this kind of converter is well matched with the inductive characteristic of usual ac loads, without the need of ac-side filter capacitors, and that the majority of modern power devices have antiparallel freewheeling diodes, deriving from their physical structure or included in the package. As a result, VS converters (VSC’s) have also become a simple and reliable solution for bidirectional power flow. On the other hand, motors and other ac loads which are usually fed by converters exhibit, in general, better performance and faster response if they are current fed rather than voltage fed. In ac motors, current control (CC) reduces the dependence on stator parameters and allows an immediate action on the flux and torque developed by the machine. In other ac loads, such as in the cases of uninterruptible power supplies (UPS’s) and ac power supplies, CC results in an increased stability of the control loop and in intrinsic short-circuit and overload protection. CC is also needed when converters are used as rectifiers (i.e., as ac/dc converters) or as active filters. In these important and relatively new applications, current must be regulated to obtain the desired active and reactive power and to minimize and/or compensate for line power factor and current harmonics. These requirements can be fulfilled, while keeping the advantages of the VSC power structure (typically, threephase bridge topology), by a closed-loop regulation of the ac-side currents produced by the converter. This solution ensures several additional advantages. Among them, it gives the control of the current waveform within the ac period, which also compensates for load transients and nonlinearities and for commutation delays. The feedback loop also results in some limitations, in that fast-response voltage modulation techniques must be employed, such as pulsewidth modulation (PWM) or discrete pulse modulation (DPM). Optimal techniques, which use precalculated switching patterns within the ac period, cannot be used, as they are not oriented to ensure current waveform control. A number of CC methods have been developed, which differ as to the kind of modulation and the type of control technique used. As regards the modulation, except for DPM, which is used mainly in the case of resonant dc-link (RDCL) Publisher Item Identifier S 0278-0046(98)07014-2.
converters, PWM is generally used. For the latter, fixedor variable-frequency or random modulation can be successfully employed. As regards the control, two main categories can be considered, linear and nonlinear. The first includes proportional integral (PI) and state feedback controllers and predictive techniques with constant switching frequency. The second comprises hysteresis and predictive controllers with on-line optimization. Alternative and innovative kinds of CC, however, have been adopted, such as delta and sigma–delta modulation and neural networks and/or fuzzy logic controls. For each of these categories, a variety of modifications and improvements of the basic principles have been developed, due to extensive work done and to the large interest in the application of this kind of converter. In today’s practice, VSC’s with CC are employed in every application where fast response, high accuracy, and a high level of performance are needed. As these features are required more and more, the interest in cheap, reliable, and high-quality current control techniques is increasing. To help the IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS readership explore the possibilities in VSC-PWM current control, this “Special Section on PWM Converter Current Control” has been prepared. An internationally recognized group of authors has described some of the novel ideas, problems, and their solutions associated with currentcontrolled PWM converters. These papers, covering all groups of PWM current control techniques, will give an impression of the present state of this technology. The Guest Editors would like to take this opportunity to thank all of the authors of this Special Section for their valuable contributions and cooperation. Also, we are grateful to the reviewers, who endeavored to ensure that the papers to be included in this Special Section are of high quality. Finally, we wish to thank the Editor-in-Chief of this TRANSACTIONS, Prof. Joachim Holtz, for his continued support, encouragement, and patience.
MARIAN P. KAZMIERKOWSKI, Guest Editor Institute of Control and Industrial Electronics Warsaw University of Technology 00-662 Warsaw, Poland LUIGI MALESANI, Guest Editor Department of Electrical Engineering University of Padova 35131 Padova, Italy
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IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 45, NO. 5, OCTOBER 1998
Marian P. Kazmierkowski (M’89–SM’91–FM’98) received the M.Sc., Ph.D., and Dr. Sc. degrees in electrical engineering from the Institute of Control and Industrial Electronics, Warsaw University of Technology, Warsaw, Poland, in 1968, 1972, and 1981, respectively. From 1967 to 1969, he was with the Industrial Research Institute of Electrotechnics (IEl), Warsaw, Poland, and from 1969 to 1980, he was with the Institute of Control and Industrial Electronics, Warsaw University of Technology, as an Assistant Professor. From 1980 to 1983, he was with RWTH Aachen, Aachen, West Germany, as an Alexander von Humboldt Fellow. During 1986–1987, he was a Visiting Professor at NTH Trondheim, Trondheim, Norway. Since 1987, he has been a Professor and Director of the Institute of Control and Industrial Electronics, Warsaw University of Technology. He was a Visiting Professor at the University of Minnesota, Minneapolis, in 1990, at the Aalborg University Centre, Aalborg, Denmark, in 1990 and 1995, and at the University of Padova, Padova, Italy, in 1993. He is also currently a Coordinating Professor in the International Danfoss Professor Programme 1997–2000, Aalborg University. He is engaged in research and theoretical work on electrical drive control and industrial electronics. He is the author or coauthor of over 90 technical papers and reports, as well as 11 books and textbooks. His latest book, with Dr. H. Tunia, is Automatic Control of Converter-Fed Drives (Amsterdam, The Netherlands: Elsevier, 1994). Dr. Kazmierkowski was Chairman of the 1996 IEEE International Symposium on Industrial Electronics held in Warsaw, Poland. He is an Associate Editor of the IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, a member of the Executive Board of the IEEE Poland Section, and the IEEE Industrial Electronics and IEEE Power Electronics Societies Joint Chapter Chairman.
Luigi Malesani (M’63–SM’93–F’94) was born in Lonigo, Vicenza, Italy, in 1933. He received the Doctor degree, with honors, in electrical engineering from the University of Padova, Padova, Italy, in 1962. From 1963 to 1964, he was a Researcher with the Centro Gas Ionizzati of CNR. In 1964, he joined the University of Padova, where, until 1975, he was Assistant Professor of Electrical Engineering. From 1968 to 1975, he was also an Associate Professor of Electronic Components. Since 1975, he has been a Professor of Applied Electronics. His interests include power electronics, circuit design, electrical machines, and automatic control. He is the author of numerous papers on these subjects. Prof. Malesani is a member of the Italian Association of Electrical and Electronic Engineers (AEI).
