A Si/SiC Hybrid Five-Level Active NPC Inverter With Improved Modulation Scheme

Compared with full-silicon-carbide (SiC) mosfet converters, the hybrid utilization of Si/SiC converters is an alternative approach to achieve the tradeoff between performance and cost. In this article, a 2-SiC hybrid five-level active neutral-point-clamped (5L-ANPC) full-bridge inverter is proposed. The proposed inverter is constructed by combining a 2-SiC hybrid 3L-ANPC half-bridge inverter and a two-level half-bridge arm. The operation principle of the proposed inverter by using the conventional modulation scheme is analyzed in detail. Furthermore, a dedicated modulation scheme is proposed to lower the conduction losses. The calculated power losses of the 2-SiC hybrid 5L-ANPC full-bridge inverter with the conventional modulation scheme and the proposed modulation scheme are addressed and compared. The proposed modulation scheme exhibits higher efficiencies under high-power conditions. But the conventional modulation scheme shows efficiency superiority under low-power conditions. Therefore, a hybrid modulation scheme is also proposed to achieve an overall high efficiency performance. A 4-kW prototype is built to evaluate the proposed topology and its modulation scheme at conversion efficiency. Experimental results and analysis show that comparing to the conventional modulation scheme, the hybrid modulation scheme can reduce power loss without increasing the hardware cost.