A Si and SiC Hybrid Arms ANPC Converter Achieving Comprehensive Optimization of Power Quality, Efficiency, and Cost

Wide bandgap (WBG) power semiconductors such as silicon carbide (SiC) can significantly improve the performance of multilevel converters. However, there are three challenges for large-scale application: high cost, limited power ratings, and reliability issues. In this paper, we propose a Si and SiC hybrid arms active neutral-point-clamped (ANPC) converter, using smaller current rating SiC devices compared to other Si devices in this topology. By employing the hybrid-frequency modulation scheme, the Si devices switch at fundamental frequency (FF) or low frequency (LF), while the SiC devices switch at high frequency (HF). The equivalent circuit of the proposed converter is derived to analyze the principle of LF current ripple compensation. The closed-loop cooperative current control strategy is proposed to realize unequal current sharing in two arms and complete LF current ripple compensation. The Si arm processes major power, while the SiC arm compensates the LF current ripple generated by the Si arm and processes minor power. The proposed topology and control strategy are validated by simulation and experimental results. Compared with the existing typical topologies, the comprehensive optimization of power quality, efficiency, and cost is realized.