Automatic tracking of MTPA trajectory in IPM motor drives based on AC current injection

The paper deals with a novel approach for the real-time tracking of the maximum-torque-per-ampere (MTPA) trajectory of an IPM motor drive. The proposed approach is based on the injection of proper tests signals and allows the MTPA trajectory to be learned and updated in the drive during steady-state conditions. The analytical development of the estimation algorithm, supported by a complete validation by simulation, is given in the paper. Finally experimental results are presented based on a prototype IPM drive system.