Chinese Journal of Electrical Engineering ›› 2015, Vol. 1 ›› Issue (1): 37-49.

• Orginal Article • Previous Articles     Next Articles

Overview on Reliability of Modular Multilevel Cascade Converters

Zhengming Zhao*, Kai Li, Ye Jiang, Sizhao Lu, Liqiang Yuan   

  1. State Key Laboratory of Power System, Tsinghua University, Beijing, 100084, China
  • Online:2015-12-25 Published:2015-12-25
  • About author:Kai Li received the B.S. degree in electrical engineering from Wuhan University, Hubei, China, in 2011. Since 2011, he has been working toward the Ph.D. degree in the Department of Electrical Engineering, Tsinghua University, Beijing, China. He was a Visiting Scholar at the Center for Power Electronics Systems, Virginia Tech, Blacksburg, VA, USA, from September 2013 to February 2015. His research interests include modular multilevel converters, PWM strategies and reliability of power electronics converters.
    Ye Jiang received the B.S. degree in electrical engineering from Tsinghua University, Beijing, China, in 2014, where she is currently working toward the Ph.D. degree in electrical engineering. Her research interests include modeling and application techniques of power semiconductor devices.
    Sizhao Lu received the B.S. and M.S. degree in electrical engineering from Harbin Institute of Technology, Harbin, China, in 2008 and 2010, respectively. He is currently working toward the Ph. D. degree with the Department of Electrical Engineering, Tsinghua University, Beijing, China. He was a Visiting Scholar at the Center for Power Electronics Systems, Virginia Tech, Blacksburg, VA, USA, from February 2012 to November 2013.
    His research interests include high-frequency high power threelevel DC-DC converters and Modular Multilevel Converters (MMC).
    Liqiang Yuan received the B.S. and Ph.D. degrees from Tsinghua University, Beijing, China, in 1999 and 2004, respectively. He became an Assistant Professor in 2004 and an Associate Professor in 2008 with the Department of Electrical Engineering, Tsinghua University, Beijing, China.
    Institute of Power Electronics and Motor System, Tsinghua University. His research interests include application techniques of semiconductor devices, solidstate- transformer (SST), and high power high voltage converters.
  • Supported by:
    zhaozm@mail.tsinghua.edu.cn

Abstract: Multi-level converters have been used extensively in modern industry which calls for energy conversion with high-power and high- or medium-voltage. Because of its modularity and scalability, the multi-level converter with modular structure can be extended to different voltage levels and has a variety of forms in practical applications. It has attracted much attention from academia in the past decade, however, as a result of the numerous vulnerable power electronics sub-modules, significant challenges remain with regards to reliability. After summarizing the current research status of modular multilevel cascade converters, the main issues of reliability are reviewed in the paper. Firstly, the failure cases are thoroughly surveyed and classified, and the main failure causes are analyzed. Secondly, the reliability evaluation methods are reviewed and applied to the modular multilevel cascade converters. Thirdly, some promising measures to improve the reliability are presented and discussed, including parameter selection, redundancy design, fault-tolerant control and so on. Then, a complete reliability-oriented design procedure for the modular multilevel cascade converters is proposed. Finally, the challenges and opportunities to improve the reliability are concluded.

Key words: Reliability, modular multi-level cascade converters, failure modes, failure rate, reliability evaluation, fault-tolerant.