Compact ASD Topologies for Single-Phase Integrated Motor Drives with Sinusoidal Input Current

Abstract

A standard configuration of an Adjustable Speed Drive (ASD) consists of two separate units: an AC motor, which runs with fixed speed when it is supplied from a constant frequency grid voltage and a frequency converter, which is used to provide the motor with variable voltage-variable frequency needed to adjust the speed ofthe motor. The integrated motor drive concept is a result of merging the two units in order to achieve the following benefits [1–3]: reducing the design and the commissioning time in complex industrial equipments, no need for a cabinet to host the frequency converter, no need for shielded cables to reduce EMI (Electro Magnetic Interference), no need for cables for the speed transducers or for other sensors for industrial process control (e.g. pressure). This solution is currently available up to 7.5 kW being not used in the medium and high power range due to a low-density integration ofthe converter caused by the large size of the passive components (electrolytic capacitors and iron chokes) and vibration ofthe converter enclosure.

This paper analyzes the implementation aspects for obtaining a compact and cost effective single-phase ASD with sinusoidal input current, investigating the physical removal of power inductors from the converter enclosure in conjunction with reducing the number of semiconductor active devices. There are two ways to do that: to integrate the inductors in the unused area of the stator yoke of the motor or to use the leakage inductance of the induction motor as a boost inductor for a PFC (Power Factor Correction) stage controlled by the inverter zero-sequence voltage component. By determining how much energy is possible to store in a corner inductor, it is proven that integrating the magnetics into the stator yoke is a feasible solution. Topologies of single-phase converters that take advantage ofthe motor leakage inductance are analyzed. The installed power in silicon active devices of these topologies is compared with a standard situation, showing that this will involve higher cost. As the iron core ofthe inductors is not suitable for high frequency operation, higher core losses will occur, but outside the converter enclosure. The advantages are: the reduction of the number of active semiconductor devices, the reduction ofthe ASD size and the better integration potential.

Key Words:

• AC machines
• Adjustable speed drives
• Converter circuits
• Converter control
• Induction motors
• Integrated adjustable speed drives
• Modulation strategies
• Passive components
• Power factor correction
• Single phase systems

Additional information

Notes on contributors

Christian Klumpner

Christian Klumpner was bom in Resita, Romania, in 1972. He received his B.Sc. degree in electromechanical engineering from the University of Resita, Romania in 1995, and his M.Sc. and Ph.D. degrees in electrical engineering from “Politehnica” University of Timisoara, Romania, in 1996 and 2001, respectively. From 1996 to 1997, he was with Bee Speed, Timisoara, Romania and from 1997 to 2000, he was a Ph.D. student at “Politehnica” University of Timisoara, Romania. Between 1998–2000, he was a Guest Researcher at Institute of Energy Technology, Aalborg University, Denmark, where he was working with matrix converters, in conjunction with his Ph.D. thesis, under the auspices of the Danfoss Professor Programme. From 2001 to 2003 he was a Research Assistant Professor at the same Institute, continuing the research work in direct power conversion under the auspices of the Innovation PostDoc Programme supported by the Danish Research Agency and Danfoss Drives A/S. As of October 2003, he is a Lecturer at the School of Electrical Engineering, University of Nottingham, UK. His research area is in power electronics and ac drives, with special focus on direct power conversion.

Frede Blaabjerg

Frede Blaabjerg (S’86-M’88-SM97-F’03) was born in Erslev, Denmark, on May 6, 1963. He received the M.Sc.EE. from Aalborg University, Denmark in 1987, and the PhD. degree from the Institute of Energy Technology, Aalborg University, in 1995. He was employed at ABB-Scandia, Randers, from 1987–1988. During 1988–1992 he was a PhD. student at Aalborg University. He became an Assistant Profes-sor in 1992 at alborg University, in 1996 Associate I Professor and in 1998 full professor in power electronics and drives the same place. In 2000 he was visiting professor in University of Padova, Italy as well as he became part-time programme research leader at Research Center Risoe in wind turbines. In 2002 he was visiting professor at Curtin University of Technology, Perth, Australia. His research areas are in power electronics, static power converters, ac drives, switched reluctance drives, modelling, characterization of power semiconductor devices and simulation, power quality, wind turbines and green power inverter. He is involved in more than fifteen research projects with the industry. Among them has been the Danfoss Professor Programme in Power Electronics and Drives. He is the author or co-author of more than 350 publications in his research fields including the book “Control in Power Electronics” (Eds. M.P. Kazmierkowski, R. Krishnan, F. Blaabjerg) 2002, Academic Press. Dr. Blaabjerg is a member of the European Power Electronics and Drives Association and the IEEE Industry Applications Society Industrial Drives Committee. He is also a member of the Industry Power Converter Committee and the Power Electronics Devices and Components Committee in the IEEE Industry Application Society. He is associated editor of the IEEE Transactions on Industry Applications, IEEE Transactions on Power Electronics, Journal of Power Electronics and of the Danish journal Elteknik. He has served as member of the Danish Technical Research Council in Denmark 1997–2003 and from 2001–2003 he was chairman. He has also been chairman of the Danish Small Satellite programme and the Center Contract Committee which supports collaboration between universities and industry. He became a member of the Danish Academy of Technical Science in 2001 and in 2003 he became a member of the academic council. From 2002–2003 he became a member of the Board of the Danish Research Councils. In 2004 he became chairman of the programme committee Energy and Environment. He received the 1995 Angelos Award for his contribution in modulation technique and control of electric drives, and an Annual Teacher prize at Aalborg University, also 1995. In 1998 he received the Outstanding Young Power Electronics Engineer Award from the IEEE Power Electronics Society. He has received four IEEE Prize paper awards during the last six years. In 2002 he received the C.Y. O’Connor fellowship from Perth, Australia , in 2003 the Statoil-prize for his contributions in Power Electronics and in 2004 the Grundfos Prize in acknowledgement of his international scientific research in power electronics.

Paul Thøgersen

Paul B. Thoegersen was bORN in Thy, Denmark, in 1959. He received the M.sc.E.E. and Ph.D. degrees from Aalborg University, Aalborg East, Denmark, in 1984 and 1989, respectively. He was an Assistant Professor at Aalborg University from 1988 to 1991. Since 1991, he has been with Danfoss Drives A/S, Graasten, Denmark, as a Research and Development Engineer. In 1996, he became Manager of Technology. His research areas are frequency converters and control and simulation of ac drives. His relationship with Aalborg University has continued through participation in a number of Ph.D. program project steering committees and as the Danfoss Drives Manager of the Danfoss Professor Programme. Dr. Thoegersen was appointed as an Adjunct Professor in the Institute of Energy Technology, Aalborg University, in 1999. He also received the Angelo Award in 1999 for his contributions to the development of industrial drives. He is a member of the European Power Electronics and Drives Association and the IEEE Industry Applications, IEEE Power Engineering, and IEEE Industrial Electronics Societies.