Bi-Axis High-Frequency Sinusoidal Injection Based MTPA Control Method for Sensorless IPMSM Drives

The cross-saturation effect causes estimated position inaccuracies, making it difficult to achieve satisfactory maximum torque per ampere (MTPA) control for sensorless interior permanent magnet synchronous motor (IPMSM) drives. To reduce the influence of position estimation error on the optimal current vector angle (OCVA) tracking, a novel bi-axis high-frequency (HF) sinusoidal injection based sensorless MTPA control method is proposed. On the basis of analyzing the influence of position estimation error and parameter mismatch on the OCVA error, a bi-axis HF signal injection mechanism in the zero-mutual-inductance and MTPA frames is established to realize the position estimation and the OCVA tracking, respectively. The efficiency optimization operation criterion is constructed by extracting the excited HF current in the MTPA frame. Then the adaptive compensation mechanism of the current vector angle tracking error is designed, so that the MTPA frame finally converges to the desired position. Theoretical analysis of stability, noise sensitivity and dynamic performance shows that the proposed method can reduce adverse effects such as the cross-saturation effect. Finally, the effectiveness of the proposed method is verified on a 2.2-kW IPMSM drive platform, enhancing the precision of MTPA control for sensorless IPMSM drives.