A novel MTPA control for IPMSMs based on extremum seeking control

This paper proposes a novel maximum torque per ampere (MTPA) control strategy based on the extremum seeking control (ESC) for interior permanent magnet synchronous machine (IPMSM) drives. The insights of the MTPA characteristics are analyzed as the research foundation. Unlike the common signal injection scheme, the high-frequency current in the proposed scheme is injected in a new reference frame mathematically for the MTPA point detecting and the torque angle updating, rather than injected to the current or voltage command. The virtual current injection would not result in the torque ripples. Therefore the proposed MTPA control structure would not affect the normal speed or current control and no additional power loss exists. Moreover it is robust against the rotor flux and inductance variations caused by the change of current and temperature. The proposed scheme dose not need any on-line estimation for motor parameters or premade look-up tables. Therefore it reduces the computational burden effectively. The simulation results verify the feasibility and effectiveness of the proposed MTPA control scheme.