The LC-filtered permanent magnet synchronous motor (PMSM) drive system presents challenges due to its high-order characteristics, as well as the phase delay and voltage drop introduced between the inverter side and the motor side. These issues make traditional sensorless control methods difficult to apply directly. To address this, this paper proposes a sensorless control strategy based on a second-order generalized integrator (SOGI)-assisted high-order extended state observer (HOESO). This strategy relies solely on DC bus voltage and inverter-side currents to realize precise observation of the motor-side current and back electromotive force (BEMF), thereby significantly reducing system cost. Furthermore, the method enables gain parameter tuning merely by adjusting the observer bandwidth, and it also demonstrates that the system is stable when the estimated current is used to drive the capacitor current feedback active damping (CCFAD). In addition, the voltage differential components are extracted using the SOGI, effectively suppressing high-frequency noise interference. Experimental results obtained on an LC-filtered PMSM platform show that, under a 0.8 N·m step load at 600 rpm and 1200 rpm, the maximum motor-side current estimation errors are 0.66 A and 1.24 A, respectively, and the steady-state rotor position estimation errors are kept within 10°. Compared with direct differentiation, the SOGI-based differential extraction reduces the maximum BEMF estimation errors from 20.16 V and 47.54 V to 10.08 V and 12.96 V, respectively.
Chen et al. (Fri,) studied this question.