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 one of the methods to control IPMSMs with high efficiency. Because the motor parameters vary with magnetic saturation, MTPA control cannot be easily realized. Here, 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. The MTPA control is achieved using the estimated flux linkage plane and the gradient ascent method. The simulation results showed that the torque was maximized in two search periods, which was completed in 0.06 s. The proposed method was effective for a wide current range.