A new sensorless control strategy combining a fundamental current observer with rotating high-frequency voltage injection method for interior permanent magnet synchronous motor

To achieve permanent magnet synchronous motor low-speed sensorless operation with high accuracy and reliability, this paper systematically studies the performance limits of rotating high-frequency carrier-signal injection-based low-speed sensorless control method, which include the winding resistance and induced electromotive force, current regulators, phase lag of filters, dynamic operation behavior of the motor, the injected high-frequency voltage amplitude and frequency, multiple saliency effects, current sensor accuracy, as well as A/D conversion quantization error. The influence of each factor on the accuracy of the speed and position estimation is discussed. On this basis, a new low-speed sensorless control strategy combining a fundamental current observer with rotating high-frequency carrier-signal injection-based method is proposed to eliminate the rotor position estimation error caused by the traditional band-pass filters, reduce the rotor position estimation error caused by the motor dynamic operation and effectively improve the rotor position estimation accuracy. The simulation and experimental results show that the proposed low-speed sensorless vector control strategy has a higher rotor position estimation accuracy and a wider speed range.