Difference Voltage E/f Control and Stator Voltage Control for Induction Motor with Voltage Unbalance Compensator to Suppress Starting Current

This paper introduces a difference voltage E/f control and difference voltage stator voltage control for an induction motor with a solid-state voltage unbalance compensator (VUC) to suppress starting current. The VUC enables consistent drive performance even if voltage unbalance occurs in power grid sources by providing the zero and negative sequence voltage. However, starting current can be 5 to 6 times more than rated motor current. This leads to the necessity of an increase in the size and cost of the VUC and as well as decreasing motor efficiency. Whereas using a difference voltage E/f control or difference voltage stator voltage control can suppress the starting current to about 40% of theoretical starting current. As a result, using a difference voltage E/f control or a difference voltage stator voltage control are expected to lead to minimization of VUC size.