Efficiency Improvement of PMSM Drive System Using Discontinuous Current Control Method at Low Torque Region

Abstract

This paper proposes a discontinuous current control method to increase the efficiency of the motor drive system at the low torque operating points. At the low torque region, loss of the inverter accounts for a large proportion of the total loss compared to the loss occurring in the motor. Reducing the inverter loss at the low torque region is the key to increase the overall system efficiency. There is a motor output torque point at which the efficiency of the motor drive system is maximized at a certain speed. The maximum efficiency motor output point is determined by the motor loss and inverter loss characteristics, and the discontinuous current control method utilizes the average motor output of the maximum efficiency point. In this paper, two-phase commutation discontinuous current control method is introduced. This makes it possible to further reduce the switching loss in addition to utilizing the maximum efficiency point of the motor drive system. The validity and performance of the proposed control method are verified through experiments.