Control Method of Electrolytic Capacitorless Dual Inverter for Harmonic Compensation Under Distorted Grid Voltage

This article proposes a harmonic compensation method using an open-end winding interior permanent magnet synchronous motor driven by an electrolytic capacitorless dual inverter under grid disturbances. In a conventional electrolytic capacitorless single inverter, harmonic currents are superimposed on the output current of the inverter owing to the increase in the dc-link voltage ripple caused by grid disturbances. Consequently, the reliability of the motor drive system is reduced, and the torque ripple causes mechanical vibrations. The proposed harmonic compensation method estimates the harmonic voltage and outputs it using a compensating inverter. The experimental results show that peak-to-peak of the motor current and the 150 Hz component of the shaft torque are reduced by 10.3 and 92.4%, respectively, compared to the conventional system under unbalanced input voltage. Therefore, the improvement of reliability of a motor drive system and reduction of the torque ripple are achieved without an energy buffer under grid disturbances.