An Extremely High Efficient Three-Level Active Neutral-Point-Clamped Converter Comprising SiC and Si Hybrid Power Stages

Abstract

Three-level converters typically feature low switching loss and small filter size. In order to realize a high-power-density design for three-level converters, SiC MOSFETs may be selected instead of using Si insulated-gate bipolar transistors. However, all-SiC-MOSFET-based converters suffer from extremely high total cost. In this paper, a SiC MOSFET and Si device hybrid active neutral-point-clamped (ANPC) converter is proposed. It consists of four Si active switches and only two SiC MOSFETs. Thus, it has lower total cost compared to the all-SiC-MOSFET-based ANPC converter. Furthermore, a dedicated modulation scheme is proposed to completely move all the switching events from Si devices to SiC MOSFETs by using redundant switching states. As a result, the switching losses are significantly reduced and extremely high efficiency is achieved. The proposed converter has fully utilized the low-switching-loss advantage of SiC MOSFETs and the low-cost advantage of Si devices, which shows significant superiority in high-end grid-connected inverter and rectifier applications.