High performance induction motor drive with optimized excitation current control

A high performance induction motor drive is presented in this paper. The drive has two important features: (a) it can produce a highest possible starting/braking torque to improve the dynamic performance of the drive; and (b) it can maximize the energy efficiency when the motor operates in steady state. Both features are achieved by optimizing the excitation current (rotor flux) of the motor. A nonlinear model for the induction motor in the MT synchronous rotating frame is derived, based on which the magnetic saturation of the motor can be accurately taken into account. The principle of optimized excitation current control is elaborated. The nonlinear motor model is integrated into the indirect field oriented vector control. The control algorithm is implemented by a multi-processor digital controller. It is demonstrated through computer simulation and experiments that the drive dynamic performance is optimized and the energy efficiency is maximized. The proposed drive is particularly suitable for electric vehicle and traction applications.