Hybrid Active Flux Observer to Suppress Position Estimation Error for Sensorless IPMSM Drives

Harmonics and drifts are found in the position estimation errors of high-frequency signal injection (HFI) methods. To suppress the position estimation error, a hybrid active flux observer with disturbance rejection for both HFI method and model-based method is proposed. It fuses the position information from traditional HFI method and model-based method as the input of a disturbance observer, the estimated disturbance output can compensate measurement error for the two methods. Then a reduced-order natural speed observer is connected in a cascaded form to reject motor mechanical disturbance by estimating the load torque. Besides, a stator resistance identification algorithm is proposed, which is proved stable near zero frequency under persistent excitation condition. A tuning guideline for the whole algorithm is elaborated based on a rigorous stability analysis. Effective experiments and simulations verify the feasibility of the proposed scheme on a 0.75-kW interior permanent magnet synchronous motor drive platform.