Maximum Torque per Ampere Control of IPMSM Using Online Flux Linkage Plane Estimation Considering Cross Saturation

Interior permanent magnet synchronous motors (IPMSMs) are used for various applications and high efficiency control is required. Maximum torque per ampere (MTPA) control is a method to control IPMSMs with high efficiency. However, since the motor parameters vary with magnetic saturation, MTPA control cannot be easily realized. Here in, we propose a fully online and automatic MTPA control method. To find the MTPA point while driving the motor, it is necessary to predict the entire flux linkage surface. Therefore, the flux linkage surface is approximated by a plane from the sensor information at a specific current condition that considers the effect of magnetic cross-saturation. MTPA control is achieved using the estimated flux linkage plane and the gradient ascent method. The simulation results reveal that the torque maximized in two search periods, which was completed in 0.06 s. The proposed method is effective for a wide current range.