Power Compensation Method for Single-Phase AC Power Supplied Dual Inverter with Small Capacitor

Abstract

This study proposes a power compensation method for a single-phase ac power supplied dual inverter without a large electrolytic capacitor. In the electrolytic capacitor-less dual inverter, a primary inverter outputs a pulsating power to improve the grid power factor without a power factor correction circuit. However, the low-voltage utilization owing to the power pulsation, which reduces the motor-operating region and system efficiency, is a primary limitation of the system. The proposed method generates voltage reference values of two inverter based on the instantaneous motor power. This facilitates dealing with power flow in the electrolytic capacitor-less dual inverter. In this study, the primary and secondary inverter only output active and reactive power, respectively, using the proposed method. Consequently, a reactive power pulsation, which is unnecessary for the power factor correction, is eliminated, and the voltage utilization of the primary inverter is improved. The simulation and experimental results show that the proposed method increases the output torque and system efficiency by up to 72 % and 11.8 pt., respectively, compared with the conventional control method.