An Improved Modulation Strategy For "Sic Plus Si" Hybrid Five-Level Active Npc Inverters

The utilization of wide bandgap devices such as silicon carbide (SiC) devices can significantly reduce the switching losses due to its fast switching speed. However, it cannot be widely used because of its high cost. Thus, "SiC+Si" hybrid topology is proposed. It only replaces a part of devices with SiC devices, thus the total cost is lower than that of the all-SiC-devices-based topology. Furthermore, the efficiency of the hybrid topology can be improved by applying suitable modulation strategies. Among all of the studies on hybrid applications, few attentions have been paid to reducing the conduction losses. This paper proposes an improved modulation strategy based on "SiC+Si" hybrid five-level active neutral point clamped inverter (FL-ANPC) topology, which can not only reduce the switching losses, but also reduce the conduction losses. In addition, as only two SiC MOSFETs are used, the cost is greatly reduced compared with the all-SiC-MOSFETs-based topology. Experimental results are presented to confirm the benefits of this proposed modulation strategy of FL-ANPC inverter.