High-Efficiency operation of PWM inverter-driven hysteresis motor with short-duration overexcitation

This paper presents the new scheme for high-efficiency operation of PWM inverter-driven hysteresis motor with short-duration overexcitation. When the terminal voltage V_i of the hysteresis motor running at synchronous speed is continuously increased up to nV_i (n>1) and then continuously decreased to V_i, input currents are reduced and output power is increased at the same time. Because of this, the efficiency becomes high. In this paper, the terminal voltage is controlled by changing the modulation degree of PWM inverter continuously.