Sensorless torque VSS control of EV

Novel induction motor speed sensorless torque control optimizing both torque response and efficiency is proposed. The control is quite different than the conventional field-oriented or direct torque control. First, the produced torque is explicitly continuous output variable of control. Second, a new rotor flux observer, which allows speed sensorless operation of IM by low and zero speed, was developed. A new stator and rotor flux controller/observer based on continuous sliding mode and Lyapunov theory are developed. The proposed robust control scheme allows a smooth transition into the field weakening region and the full utilization of the inverter current and voltage capability during acceleration or regenerative braking of EV. The drive system including an 18 kW, 4 pole, 120 V battery-powered IM and a 30 kW IGBT inverter has been applied to a pick up truck (EV).