Vector control of induction motor for electric vehicles considering iron losses and its energy optimization strategy

Electric vehicle induction motors(IM)are usually characterized by their low magnetizing inductance, which causes a significant amount of iron losses especially in high-speed operation. Classical vector control is notorious by its low efficiency under light load and inaccurate control by neglecting iron losses. Firstly, a structure diagram of the IM is proposed in a synchronously rotating frame of reference based on its dynamic mathematical model including iron losses. The effects of iron losses on performance of rotor flux oriented controlled IM are then discussed, and the compensation strategies are also given under both steady-state and transient operations. Moreover, the losses of IM in operation are discussed and an energy optimization control strategy of IM driving system based on loss model is proposed, the effects of iron equivalent resistance variation on energy optimization are analyzed as well. Finally, experimental and simulation results show that the compensation strategy provides good performance on flux and torque control, and the energy optimization strategy improves the motor efficiency remarkably and has advantages of high optimization speed, small torque and speed fluctuation, which provide a sound solution for a good performance and high efficiency IM drive system for electric vehicles.