Tutorial Title: Topologies and Control of Multilevel Converters

The controllability of capacitor voltages in multilevel converters is essential to enable their use in practice. This includes the voltage balancing of the dc-link capacitors and the flying capacitor (FC) voltage control. When the number of voltage levels of neutral-point-clamped (NPC) converters is four or higher, the capacitor voltage control becomes particularly challenging. To address this issue, various new hybrid multilevel topologies and new modulation and control strategies have been proposed with many recent developments. In particular, the virtual vector/zero modulation, combined with optimal zero-sequence injection, has shown superior capability to balance the dc-link capacitor voltages through software, without the need of additional hardware. This enables conventional NPC converters with four or higher number of levels to operate independently as a single rectifier or inverter (or with a passive front end) over the full power factor and modulation index range. This tutorial will answer questions such as: How can we derive the various multilevel topologies integrating semiconductor devices, dc-link capacitors, and flying capacitors? How do we enable their capacitor voltage balance through modulation and control? This tutorial will cover the basic multilevel converter topologies, their control, and their applications. It is suitable for researchers interested in multilevel converters at various levels.

Presenters’  Information

Xibo Yuan, China University of Mining and Technology

Professor Xibo Yuan received the B.S. degree from the China University of Mining and Technology, Xuzhou, China, and the Ph.D. degree from Tsinghua University, Beijing, China, in 2005 and 2010, respectively, both in electrical engineering. He has held Professor positions at the China University of Mining and Technology and the University of Bristol. He is a Distinguished Lecturer of the IEEE Power Electronics Society, a Fellow of IET and received several best paper awards from IEEE journals and conferences and the Isao Takahashi Power Electronics Award in 2018.

His research interests include power electronics and motor drives, wind power generation, multilevel converters, application of wide-bandgap devices, electric vehicles and more electric aircraft technologies.