A Highly Reliable Three-Level Neutral-Point-Clamped Inverter With Anti-Shoot-Through Capability

In this article, a high-reliability three-level inverter construction method is proposed to address the risks of shoot through in neutral-point-clamped inverter (NPC). Several highly reliable three-level inverters are discussed in brief. Two types of risks are analyzed when capacitors are shot through. Then, two principles for constructing highly reliable inverters are summarized. Besides, a split-inductor hybrid NPC inverter with anti-shoot-through capability is constructed by using the two principles. Power switches and diodes are connected in series to form the inverter legs. Split inductor is inserted in capacitor loops to suppress the short-circuited current. As a result, the novel structure is able to suppress the shoot-through current for all capacitors and power devices. The voltage stress of all switches and diodes is half of the dc voltage and multiple freewheeling paths are maintained. Finally, simulations and experiments are presented to verify the two principles and the shoot-through current suppression performance.