Low-Cost Gate Drive Circuit for Three-Level Neutral-Point-Clamped Voltage-Source Inverter

This paper presents a new hardware implementation of gate drive circuits applied to low-power neutral-point-clamped (NPC) multilevel three-phase inverters. The proposed circuit is based on commercially available MOS-gate driver ICs (MGDs) for large-scale applications, which may reduce the total cost of implementation of NPC inverters. Only one DC power supply is required to feed all the gate drivers for the three-phase system. Detailed design procedures are presented, which include the protection circuits for avoiding hazardous switching states of the power switches. Experimental results of a laboratory prototype demonstrate the validity of the proposed circuit. These results also suggest that for achieving safe operation of snubberless power switches during transients, a hybrid implementation of each NPC phase leg, consisting of MOSFETs with voltage ratings at half the DC bus voltage and of insulated gate bipolar transistors rated at the total DC bus voltage, is recommended.