Voltage Compensation Performance of the Voltage Unbalance Compensator Using the Method of Symmetrical Components

This paper reports the voltage unbalance compensation performance of a three-phase inverter for a Voltage Unbalance Compensator (VUC) controlled by using the method of symmetrical components for an induction motor. The VUC consists of a three-phase PWM rectifier, a DC-link capacitor, and an inverter. The rectifier is connected to the power grid lines and the inverter is connected to one of the ends of the open-winding induction motor. It supplies compensating voltage and keeps the terminal voltage balanced of the induction motor when the voltage unbalances occur on the power grid. By using the method of symmetrical components, the unbalanced three-phase voltage can be represented by a combination of balanced three-phase voltages. Therefore, the compensation voltage can be easily controlled. We clarified that the voltage performance of the inverter for the VUC by simulation and experiment. The results showed that the proposed VUC suppressed the voltage unbalance.