Maximum Torque Per Ampere (MTPA) Control for Interior Permanent Magnet Synchronous Machine Drives Based on Virtual Signal Injection

This paper introduces a novel virtual signal injection-based control method for maximum torque per ampere (MTPA) operation of interior permanent magnet synchronous machine (IPMSM) drives. The proposed method injects a small virtual current angle signal mathematically for tracking the MTPA operating point and generating d-axis current command by utilizing the inherent characteristic of the MTPA operation. This method is parameter independent in tracking the MTPA points, and it does not inject any real signal to current or voltage command. Consequently, the problems associated with real high-frequency signal injection, such as increases in copper and iron loss can be avoided. Moreover, it is robust to current/voltage harmonics and motor torque disturbances. The proposed method is verified by simulations and experiments under various operating conditions on a prototype IPMSM drive system.