An Efficiency Study of SiC-MOSFET Based Three-Level NPC Inverters

The demand for high-performance inverters is also growing with the increasing renewable energy usage. Among various inverters topologies, the three-level neutral point clamped inverters (3LNI) are widely used due to higher voltage capability and lower output voltage harmonics. The 1-type, T-type, and Active-type are well-known types of 3LNIs. This article derives the required mathematical formulas for efficiency analysis for the types above. Besides, it shows how using silicon Carbide (SiC) power devices can improve 3LNIs performance in high power/voltage range. In this regard, an experimental setup with 800V DC voltage, the line-to-line voltage of 380Vrms, 8.8A output phase current, and 40 kHz switching frequency has been developed. The experimental results conform to mathematical calculations and demonstrates that the efficiency and power density of the SiC-based 3LTI can improve up to 98% and 8.5W/inch3, respectively.