说明：  This paper presents a simplified algorithm of controlling an interior permanent magnet synchronous motor (IPMSM) for maximum torque per ampere (MTPA) of stator current with inherent non-linearities of the motor. Contrary to the conventional control of IPMSM with d-axis current equals to zero, a non-linear expression of d-axis current has been derived and subsequently incorporated in the control algorithm for maximum torque operation. In this work, it is observed