A Novel Hybrid Active-Passive Neutral-Point-Clamped Multilevel Conversion Topology

Abstract

This paper presents a novel multilevel neutral-point-clamped (NPC) topology featuring a combination of active (transistor) and passive (diode) clamping. The topology leverages the main benefits of both purely-passive and purely-active NPC topologies. It allows concentrating switching loss in devices with a low commutation power-loop inductance, enabling high switching speeds with low losses and voltage overshoots. At the same time, the proposed topology features a moderate complexity since the number of transistors increases only linearly with the number of levels. The proposed topology represents a trade-off solution especially suitable to implement NPC converter legs with a large number of levels. Detailed simulation results are presented to illustrate the operation of this novel hybrid NPC topology under four levels.