A novel three-phase multilevel inverter topology with reduced device count for open-end winding motor drives

A novel three-phase multilevel inverter topology for open-end winding motor drives is proposed, featuring a reduced number of power devices. According to such a topology, only two of the motor phase windings are fed by a single-phase neutral point clamped inverter from one side, and a single-phase full bridge inverter from the other, the third motor phase being connected between the midpoints of the two inverters. The proposed topology can generate six different voltage levels in each motor phase and compared to a conventional three-phase three-level neutral point clamped inverter features a reduced amount of power devices and a higher efficiency. Simulations dealing with steady-state and transient conditions have been performed on a 1kW permanent magnet synchronous motor drive to demonstrate the effectiveness of the proposed configuration in a wide operating range.