DC-Link Current Harmonics Reduction of a Dual Inverter with a Lower Floating Capacitor Voltage

This study aimed to reduce the input DC-link current harmonics in a dual inverter with a floating capacitor by operating the primary inverter in six steps. The proposed control strategy reduces the floating capacitor voltage by providing a phase-angle difference in the dual inverter depending on the load conditions. The secondary inverter compensates for the lower order harmonics owing to the six-step operation to supply a sinusoidal voltage to the motor. The operating range and DC-link current harmonics were theoretically analyzed and compared with those of the conventional strategy. Furthermore, the performance of the proposed strategy and the floating capacitor voltage dependencies of the input-current harmonics were experimentally demonstrated.