Robust maximum torque per amp (MTPA) control of PM-assisted SynRM for tractions applications

Recently, permanent magnet assisted (PMa)-synchronous reluctance motors (SynRM) have been introduced as a possible tractions motors in hybrid electric vehicle applications. In order to achieve maximum torque per ampere (MTPA), knowledge of the motor parameters is necessary. Due to the high ambient temperature inside the engine cavity and also saturation effect, variation of the motor parameters such as inductances and permanent magnets flux density is not avoidable. Off-line models for estimating the motor parameters are known as a computationally intensive method, especially when the effect of cross saturation and permanent magnet flux deterioration are included. In this paper, a practical maximum torque per ampere control scheme along with a simple parameter estimator for PMa-SynRM is introduced. This method is capable of maintaining the MTPA condition and stays robust against the motor parameters variations. To verify the validity and feasibility of the proposed controller, several simulations and experiments results on a low power laboratory prototype PMa-SynRM have been presented.