Compensation of Position Estimation Error in PMSM Sensor-less Control Based on High Frequency Square Wave Injection

The high-frequency square-wave injection method is widely used to estimate rotor position at low speed. However, the accuracy and reliability of the method are greatly affected by the dead-time effect. The specific expression of position error is deduced. On this basis, a dead zone error reduction method based on second-order general integrator (SOGI) is adopted to improve the accuracy of position estimation. Besides, low-pass filter needs to be introduced into the current loop, which will bring delay to the system. Aiming at this problem, a delay compensation algorithm is adopted, which can effectively improve the accuracy of position estimation. Results of simulation verify the effectiveness of the methods and their applicability to PMSM sensorless control systems.