A vector control scheme for EV induction motors with a series iron loss model

Abstract

Electric vehicle (EV) motors are characterized by 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 pulsewidth modulation (PWM) switching makes a significant amount of eddy-current loss and hysteresis loss, especially in high-speed operation. If we simply neglect the iron loss, then it detunes the overall vector controller and results 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) We propose a series R-L model that accounts 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 paper, we derive a rotor-flux-oriented vector control scheme for the series model and analyze the flux error, orientation angle error, and torque error caused by iron loss. Finally, we demonstrate the effectiveness of the proposed control method through computer simulation and experimental results.