Three-Level Inverter Scheme with Common Mode Voltage Elimination and DC-Link Capacitor Voltage Balancing for an Open End Winding Induction Motor Drive

A DC link capacitor voltage balancing scheme for an three-level inverter with open end winding induction motor drive is proposed in this paper. The multiplicity of the switching combinations of the inverter voltage locations is best exploited to arrive at the capacitor balancing criterion. All the inverter vector locations, which has unbalancing effect on the capacitor voltages, exhibits greater multiplicity than the conventional neutral point clamped three-level inverter. These switching combinations can be used properly to balance the capacitor voltages. The effect of various switching combinations on the capacitor voltages is established and then a closed loop hysteresis controller based capacitor voltage balancing scheme is proposed. The performance of the proposed scheme for various operating conditions is demonstrated through simulation and experimental results. A 1.5 kW induction motor with open end windings is used for experimental verification of the proposed scheme