A research of the status of the PWM of NPC three-level inverter

With science and technology development, the application of inverters in the AC frequency conversion speed regulation system has become a hot research field. Among them, the three-level inverter has received extensive attention from scholars of its low requirements for the withstand voltage level of the device, high switching frequency, smooth output waveform, etc., and the three-level inverter also makes it possible to make the voltage inverter large capacity and high performance. Therefore, the research and development of three-level inverters is of great significance both in technology and practical application. This paper first describes the development of three-level inverters and two modulation methods (SPWM and SVPWM), then introduces the principles of three-level inverters and the two modulations. Next, it summarizes several typical modulation strategies of NPC three-level inverters, followed by comparing and analyzing their advantages and disadvantages. The final part of this paper makes a summary of this text and discusses the future trends and possible research in this area.