Sensorless Control Strategy for Permanent Magnet Synchronous Motors Based on Enhanced SOGI-FLL with Limit Cycle Oscillator

In the sensorless control system of permanent magnet synchronous motor (PMSM), the non-ideal factors such as parameter changes will introduce disturbance to the observed variables, and the traditional sensorless algorithm based on the second-order generalized integrator with frequency-locked loop (SOGI-FLL) has low disturbance suppression ability. This paper proposes an enhanced SOGI-FLL with limit cycle oscillator for PMSM sensrrless drives. By constructing a nonlinear oscillator structure on the SOGI-FLL algorithm, this method can suppress the fundamental amplitude variation and harmonic disturbance in the flux observation. The experimental results show that the proposed algorithm can improve the robustness of the PMSM sensorless drives.