Zero speed braking control strategy for permanent magnet motor

Using three-phase permanent magnet AC motor (PM motor) as drive part of electric vehicle (EV), the motor must achieve zero speed braking when the vehicle brakes to stop on the slope. Braking force and motor rotation have the same direction when the vehicle is braking in the downhill; and the direction are opposite when braking in the uphill. Therefore, the general control strategy for PM motor cannot realize this function. This paper introduces a new zero speed braking control strategy according to the inherent characteristics of PM motor. By analyzing the structural characteristics and electromagnetic properties of PM motors, this paper proposed a control strategy by combination of the DC chopper and the space voltage vector method. This paper describes the key ideas and method of the control strategy. Experimental results of EV demonstrate the effectiveness of the proposed control strategy.