Feedforward Flux Observer Based on SOGI Current Extractor for PMSM Sensorless Control

The flux estimation has been greatly affected by the dc offset, integral saturation and harmonics. To solve the problems, this paper proposes an improved feedforward compensation flux observer, implemented with the selftuning regulator, the second-order generalized integrator (SOGI), and phase-locked loop (PLL), is discussed for estimated flux calculation. The self-tuning flux regulator can dynamically calibrate estimated flux according to the motor current and parameters, which could effectively avoid the integral saturation. The SOGI current extractor can effectively eliminate dc offset and reduce the harmonics without introducing much amplitude attenuation and phase shifting deviation. Rotor angle and speed estimation error can be tracked with a phase-locked loop (PLL), based on the accurate flux estimation that feedforward compensation flux observer provide. The effectiveness of proposed method is validated by simulation and experimental results.