Research on Sensorless Control Algorithm for PMSM with Improved Super-Twisting Sliding Mode Observer Based on SOGI-FLL

To enhance the performance of position sensorless control in internal permanent magnet synchronous motor(PMSM) drives, a sensorless control system utilizing a second-order adaptive super-twisting algorithm sliding mode observer(ASTA-SMO) and second-order generalized frequency-locked loop (SOGI-FLL) is proposed. This approach addresses the limitations of traditional sliding mode observers(SMO), including chattering, high-order harmonics, and external noise. In order to overcome these drawbacks, the switching term in the conventional sliding mode method is replaced with a second-order sliding mode, resulting in an improved algorithm. The fixed gain is substituted with an algorithm that dynamically adjusts the sliding mode coefficient online. This enhancement enables a broader application range and reduces the impact of position error within various speed ranges. In addition, the phase-locked loop has been improved by using a second-order generalized integrator(SOGI) instead of a traditional low-pass filter to achieve adaptive filtering, reduce the 5th and 7th harmonic content in the back electromotive force(EMF), reduce position errors, and enhance position stability.