A new vector control scheme considering iron loss for electric vehicle induction motors

Electric vehicle (EV) motors are characterized for their low inductance and high current density, so that they run at high speed and produce a high starting torque. Due to the low inductance coil design, the current ripple caused by PWM switching makes a significant amount of eddy current loss and hysteresis loss, especially in the high speed operation. If one simply neglects the iron loss, then overall vector control scheme is detuned, resulting in an error in the torque control. The iron loss is modeled, in general, by a parallel resistor R_M to the magnetizing inductor L_M. The authors propose a series R-L model that can account for the effects of the iron loss. A major advantage of the series model is that it does not increase the number of state variables in developing a vector control. In this work, they derive a rotor flux oriented vector control scheme for the series model, and analyze the flux error, orientation angle error, torque error caused by iron loss. Finally, the demonstrate the effectiveness of the proposed control method through computer simulation and experimental results