An Improved Estimation Strategy for IPMSM Sensorless Control Over Wide Speed Range

Due to the modeling uncertainty and inverter non-linearity, a low signal-to-noise ratio problem is induced in the extended electromotive force (EEMF) at low speeds in the sensorless control system of interior permanent magnet synchronous motor (IPMSM). The low signal-to-noise ratio problem is transferred to the estimation error of rotor position and speed through a phase-locked loop (PLL), significantly deteriorating the accuracy of sensorless control system. This paper proposes a new control strategy based on a new linear extended state observer combined with complex coefficient filter to estimate the EEMF based on active flux. Specific d-axis current can excite the EEMF and enable motors to work at the low speed range. Simulation results demonstrate that the proposed method ensures the higher accuracy of IPMSM sensorless control over a wide speed range.