A four-level open-end winding induction motor drive with a nested rectifier-inverter combination with two dc power supplies

Abstract

This paper proposes a new nested rectifier–inverter circuit topology for a four-level (4-L) open-end winding induction motor drive (OEWIMD). To realize the 4-L inversion, the nested rectifier–inverter topology operates with unequal dc-link voltages, which are in the ratio of 2:1. The proposed topology has the inher ent ability of avoiding the overcharging of the lower dc-link voltage capacitorbyitshighervoltagecounter-partunlikeinthecaseofthe power circuit configuration proposed in the earlier literature. This paper also proposes a new sample-averaged zero-sequence elim ination pulsewidth modulation (PWM) scheme for the proposed circuit configuration to avoid the flow of zero-sequence current through the motor windings. It is shown that the proposed power circuit is also capable of displaying immunity to a particular type of fault, as it can produce the same output voltage despite the un balancing of oneofthedc-linkcapacitor voltages without changing the modulation strategy. The proposed 4-L OEWIMD along with the associated PWM schemes is simulated and is validated with experimental results