Capacitors for Power Electronics – from an Application Perspective

Abstract: Capacitors are one of the key components in typical power electronic systems in terms of cost, volume, and reliability. Power electronics applications are consuming unprecedented quantities of electrolytic capacitors, film capacitors, and ceramic capacitors. This tutorial aims to the sizing, modeling, and reliability of capacitors from an application perspective, focusing on both classical and emerging power electronics applications. It will start with a brief introduction to different types of capacitors used in power electronics applications, and their respective technology limits and emerging developments. Then the performance factors and sizing criteria of capacitors for various power electronic applications will be discussed. A model based design approach and multi-objective optimization for capacitor banks will be presented. A two-terminal active capacitor concept will also be presented, which enables reduced design cost or
increased power density in a couple of power electronic applications by directly replacing passive capacitors. Condition monitoring of capacitors will be introduced in terms of methodologies and principles. Throughout the tutorial, a few step-by-step examples will be included, such as capacitors for DC-DC converters, Modular Multi-Level Converters (MMC), and photovoltaic inverters. The tutorial covers the state-of-the-art research outcomes with balanced contents for both audiences with entry-level and advanced knowledge on the topic. It intends to bridge the gaps among university researchers, industry power electronic designers, and capacitor manufacturers. The target participants are: 1) University researchers who are interested in practical considerations in capacitors for power electronic applications, latest capacitor technologies, and active capacitor concepts; 2) Industry power electronic designers who would like to have better understanding in how to optimally sizing capacitors to fulfill electrical, thermal, and reliability aspects of product specifications with cost and performance optimization; and 3) Capacitor manufacturers who would like to know more about the specific demands from various power electronic applications, to be better at supporting customers with optimized and dedicated capacitor solutions.

Huai Wang is currently a Research Thrust Leader with the Center of Reliable Power Electronics (CORPE), and the Vice Leader of the Efficient and Reliable Power Electronics Research Program at Aalborg University, Denmark. His research addresses the fundamental challenges in modelling and validation of power electronic component failure mechanisms, and application issues in system-level predictability, condition monitoring, circuit architecture, and robustness design. In CORPE, he also leads a capacitor research group including multiple PhD projects on capacitors and its applications in power electronic systems, and collaborates with various industry companies across the value chain from manufacturers to end-users of capacitors. Prof. Wang is the lecturer of a 2-day Industry/PhD course on Capacitors in Power Electronics Applications at Aalborg University. He has given 21 tutorials at leading power electronics and reliability engineering conferences (e.g., ECCE, APEC, IECON, PCIM, ESREF, etc.) and a few keynote speeches in the above research areas. His book on Capacitors in Power Electronics Applications: Sizing, Modeling, and Reliability expects to be published by Wiley in 2019. Prof. Wang received his PhD degree from the City University of Hong Kong, Hong Kong, China, and Bachelor degree from Huazhong University of Science and Technology, Wuhan, China. He was a visiting scientist with the ETH Zurich, Switzerland, from August to September, 2014 and with the Massachusetts Institute of Technology (MIT), Cambridge, MA, USA, from September to November, 2013. He was with the ABB Corporate Research Center, Baden, Switzerland, in 2009. He received the Richard M. Bass Outstanding Young Power Electronics Engineer Award from the IEEE Power Electronics Society in 2016, and the Green Talents Award from the German Federal Ministry of Education and Research in 2014. He is currently the Chair of IEEE PELS/IAS/IE Chapter in Denmark. He serves as an Associate Editor of IET Power Electronics, IET Electronics Letters, IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS, and IEEE TRANSACTIONS ON POWER ELECTRONICS.