Impact of Inductor Placement on DC Bus Capacitor of Adjustable Speed Drives under Non-Ideal Supply Voltage Conditions

Abstract

Diode bridge front-end Adjustable Speed Drives (ASDs) generally have an inductor either in the DC side (DC choke) or in the AC side (AC choke). Since both the types of ASDs are commercially widely used, a comparison of their behavior under normal and abnormal grid conditions is of interest. It is identified in this work that there exists a difference in the ripple current through the DC bus capacitor between the two variants. Further, the difference in the ripple current varies depending on the type of the disturbance and its level. As an outcome of the study, it is identified that the stress levels arising in the DC choke variant on the DC bus capacitor are lesser compared to the corresponding AC choke variant under balanced, unbalanced, and distorted grid voltage conditions, for the same value of the equivalent inductance in the AC and DC side. In order to match the stress levels arising in the DC bus capacitor between the ASDs with DC and AC choke, it is found that a 50% higher value of inductance is required in an AC choke variant. The effects are analyzed by simulations and validated using an experimental setup.

Keywords:

• AC choke
• DC choke
• capacitor heating factor
• capacitor stress
• unbalance
• harmonics

Additional information

Notes on contributors

Seshadri Gopalan

Seshadri Gopalan received the B.Tech. degree in electrical and electronics engineering from the Velammal Engineering College (affiliated to Anna University, Chennai), India, in 2011, and the M.Tech. degree in electrical engineering with specialization in power electronics and electrical drives from the Sardar Vallabhbhai National Institute of Technology (NIT), Surat, India, in 2016. He is currently working toward the Ph.D. degree in electrical engineering at the Indian Institute of Technology (IIT), Madras, Chennai, India. During 2011–2014, he was working as a Systems Engineer in Tata Consultancy Services, Chennai, India. He was a University Rank Holder in his B.Tech and Gold Medalist in his M.Tech. His research interests include motor drives, power electronics, and power quality effects on drives.

Krishna Vasudevan

Krishna Vasudevan received his B.Tech. degree in electrical engineering (power) from the Indian Institute of Technology (IIT), Madras, in 1989, and his M.E. degree in electrical engineering from Indian Institute of Science, Bangalore, in 1991. Between 1991 and 1992 he worked as a senior engineer in Kirloskar Electric Company, responsible for developing UPS systems. He received his Ph.D. in electrical engineering from IIT, Madras, in 1996. Between 1996 and 1998, he was also Senior Engineer with M/s Lucas TVS Ltd., involved in the performance improvement of automotive alternators. From 1998 he has been with the Department of Electrical Engineering at IIT Madras, where he is currently a Professor. Dr. Krishna is a recipient of Best student Award during his Master’s study at IISc, and is a recipient of DAAD fellowship for research in Germany during 2006. He has guided several students at the PhD, Masters and Btech levels. He has also interacted with several industries during the course of his tenure at IITM by way of consultancy and technology development. His research interests are in the area of power electronics for renewable energy, machines and drives.

Dinesh Kumar

Dinesh Kumar received Master of Technology (M. Tech) in power system engineering from Indian Institute of Technology (IIT), Roorkee, India, in 2004, and Ph.D. degree in power electronics from the University of Nottingham, U.K., in 2010. From 2004-2005, he served as a Lecturer in the Electrical Engineering Department at National Institute of Technology, Kurukshetra, India. In 2006, he joined Technical University Chemnitz, Germany as a Research Fellow in Power Electronics. Since 2011, he has been with Danfoss Drives A/S, Denmark, where he is involved in many research and industrial projects. He is an Adjunct Associate Professor with School of Electrical Engineering and Robotics, Faculty of Engineering, Queensland University of Technology, Australia. He is a member of the IEC standardization Working Group in TC77A, TC22/SC22G and SyC LVDC committee. He is the Editor in-Chief of International Journal of Power Electronics and the Associate Editor of IEEE Transaction on Industry Applications, IEEE Access Journal, and member of Editorial board of IEEE Transportation Electrification eNewsletter. Dr. Dinesh was the recipient of two IEEE best paper awards. His current research interests include motor drive, harmonic analysis and mitigation techniques, power quality and electromagnetic interference in power electronics.