Improved Flux Linkage Observer and Anti-Disturbance Transition for Wide-Speed Domain PMSM Sensorless Hybrid Control Strategy

In the permanent magnet synchronous motor wide-speed domain position sensorless hybrid control strategy, position errors caused by low-pass filters in the flux linkage observer reduce the position observation accuracy of the medium–high speed range, which can lead to a degradation of the sensorless control performance. At the same time, a smooth transition from the zero-low speed range to the medium–high speed range is critical. Therefore, a position error compensator based on the Luenberger observer and a sensorless hybrid control strategy with an anti-disturbance transition algorithm is proposed. For the flux observer in the medium–high speed range, a position error compensator based on the Luenberger observer is proposed to compensate for the estimated rotor position in real-time, which reduces the position error caused by the low-pass filter and improves the position estimation accuracy. Aiming at the transition stage in the hybrid control strategy, a velocity fluctuation compensation term with q-axes current feedback is added to the speed-weighted transition algorithm, which reduces speed and torque fluctuation, and enhances the anti-disturbance ability of this stage. In addition, after the transition to the medium–high speed range, the velocity fluctuation compensation term will also decrease to zero, which avoids the influence of the velocity fluctuation compensation term on the control performance of the medium–high speed range. The experimental results show that the proposed sensorless hybrid control strategy has favorable steady-state performance and dynamic performance in the wide-speed domain.