A Four-Level Open-End Winding Induction Motor Drive With a Nested Rectifier-Inverter Combination With Two DC Power Supplies

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 inherent ability of avoiding the overcharging of the lower dc-link voltage capacitor by its higher voltage counter-part unlike in the case of the power circuit configuration proposed in the earlier literature. This paper also proposes a new sample-averaged zero-sequence elimination 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 unbalancing of one of the dc-link capacitor 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.