中国电气工程学报（英文） ›› 2020, Vol. 6 ›› Issue (4): 42-52.doi: 10.23919/CJEE.2020.000029

所属专题： Special Issue on Switched-Capacitor Circuits and Partial Processing Techniques

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  • 收稿日期:2020-09-22 修回日期:2020-11-15 接受日期:2020-11-24 出版日期:2020-12-25 发布日期:2021-01-15

Switched-capacitor Multi-level Inverter with Equal Distribution of the Capacitors Discharging Phases*

Zhiyuan Xu1, Xiaofeng Zheng1, Tong Lin1, Jia Yao1,*, Adrian Ioinovici2   

  1. 1. College of Automation, Nanjing University of Science and Technology, Nanjing 210014, China;
    2. College of Automation, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
  • Received:2020-09-22 Revised:2020-11-15 Accepted:2020-11-24 Online:2020-12-25 Published:2021-01-15
  • Contact: *E-mail: 2636200534@qq.com
  • About author:Zhiyuan Xu received his B.E. degree in electrical engineering from Heilongjiang University of Science and Technology, Harbin, China. He is currently studying for his master’s degree at Nanjing University of Science and Technology, Nanjing, China. His current research interests include switch capacitor, high conversion ratio dc/dc converters.
    Xiaofeng Zheng received his B.E. degree in electrical engineering from Nanjing University of Science and Technology, Nanjing, China. He is currently studying for his master’s degree at Nanjing University of Science and Technology, Nanjing, China. His current research interests include switch capacitor, power factor correction.
    Tong Lin received his B.E. degree in electrical engineering from Hebei University of Science and Technology, Shijiazhuang, China. He is currently studying for his master’s degree at Nanjing University of Science and Technology, Nanjing, China. His current research interests include digital control power factor correction, active clamp soft switching technology, high conversion ratio dc/dc converters, switch capacitor.
    Jia Yao (S’13-M’15) was born in Nanjing, China. She received the B.S. and M.S. degrees in instrumentation engineering from Southeast University, Nanjing, China in 2002 and 2005, respectively, and Ph.D. degree in electrical engineering from Southeast University, in 2015.She is currently an associated professor at Nanjing University of Science and Technology, China. From 2005 to 2010, she was a senior hardware engineer with Mindray Medical bio-medical Electronics Co., Ltd. During 2012-2014, she was a visiting scholar at University of California, Irvine, CA, USA.Her research interests include high conversion ratio dc/dc converters, modeling technique of switching converters and photovoltaic/battery applications.
    Adrian Ioinovici (M’84-SM’85-F’04) is a professor with the Nanjing University of Aeronautics and Astronautics, China, and with the Holon Institute of Technology, Israel. He got the IEEE Fellow grade for “pioneering work in switched-capacitor converters”.He authorized the books Computer- Aided Analysis of Active Circuits (New York: Marcel Dekker, 1990) and Power Electronics and Energy Conversion Systems, Volume 1: Fundamentals and Hard-switching Converters (Wiley, 2013), translated to Chinese in 2017, and the chapter Power Electronics in Encyclopedia of Physical Science and Technology (San Francisco, Academic, 2001). His main research interests are switching-capacitor converters and inverters, large DC gain converters, soft-switching converters.He gave the keynote speech at the 19th China Power Supply Society Conference (2011, Shanghai), and at ECCE Asia (2012, Harbin). Prof. Ioinovici received the Best Paper Award of the IEEE IAS Renewable and Sustainable Energy Conversion Systems Committee at ECCE’12, USA. He served a number of terms as the Chairman of the Technical Committee on Power Systems and Power Electronics of the IEEE CAS Society.Prof. Ioinovici served repetitive terms as an associate editor for Power Electronics of the IEEE Transactions on Circuits and Systems I, and of Journal of Circuits, Systems, and Computers (JCSC). He was an overseas advisor of the IEICE Transactions, Japan and a guest editor of Special Issues of the IEEE Transactions on CAS (1997 and 2003) and of JCSC (2003). He is currently serving as an associate editor for IEEE Transactions on Power Electronics and IEEE Transactions on Industrial Electronics. He served as a guest editor for the special issue “Applications of Predictive Control in Microgrids”-IEEE Transactions on Industrial Electronics, 2020.
  • Supported by:
    *National Natural Science Foundation of China(51707096).

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Abstract: A new switched-capacitor (2n+1) levels inverter with a single input source and equal charge of the capacitors at the input voltage Vin is presented. Compared with its peers from the same class of inverters, the proposed one features an equal or lower components count referred to the boost factor. And, it presents an additional advantage: each voltage level can be obtained by using different capacitors in the discharging phase, such that the decreasing part of the staircase output waveform can be synthesized with different switching topologies than those used in the increasing part. As a consequence, all the capacitors are discharged at the same voltage value at the end of each half-cycle, allowing for the use of smaller capacitors of equal values. When the capacitors are connected in parallel in the charging phase, there is no need to equalize their voltages, so no additional current spikes appear. This also implies less electromagnetic emission (EMI). Two types of modulation strategies are proposed. A half-height fundamental switching frequency modulation strategy allows for reaching the desired peak of the output voltage during the highest voltage level operation. It is advantageous in application of the inverter as a front end of a grid supplied by green sources of energy. A high frequency (fs=200 kHz) modulation strategy accompanied by a duty-cycle control is advantageous for applications which require miniaturization. A 9-level switched-capacitor multi-level inverter (SCMLI) is analyzed and designed. The power losses are calculated. The experimental results for a 9-level inverter with Vin=40 V, Vout=110 Vrms 50 Hz, 200 W confirm the theoretical expectations.

Key words: Switched-capacitor, multi-level inverter, half-height frequency modulation