Parameter independent maximum torque per ampere (MTPA) control of IPM machine based on signal injection

This paper presents a new maximum torque per ampere (MTPA) control method for Interior Permanent Magnet Synchronous Machine (IPMSM) drives. The proposed method uses the conventional speed control scheme, where speed control loop produces the magnitude of the stator current reference. According to the current angle in the rotor reference frame, θ, the current reference is decomposed to the d-/q-axis current references. To operate IPMSM in the MTPA mode, this paper presents the new MTPA tracking method using signal injection. This method works based on the inherent definition of MTPA, which is that the torque variation due to the current angle variation should be zero at the specific torque. The proposed method detects the accurate current angle where the magnitude of the stator current is the minimum at the specific torque without any pre-made look-up tables and machine parameters.