Position Sensorless Control of Permanent Magnet Synchronous Generators Based on Parameter Disturbance Compensation to Mitigate Estimation Error Offset

The Permanent Magnet Synchronous Mud Generator (PMSMG) serves as the primary power source for downhole power supply systems in oilfields that operate in high-temperature environments. Given that the PMSMG functions under complex conditions, precise rotor position information is of paramount importance. However, high-temperature mechanical position sensors are not only cost-prohibitive but also face significant challenges regarding lifespan and reliability. While sensorless control technology emerges as a promising alternative, it encounters estimation biases caused by temperature-induced parameter variations. To address these issues, this paper proposes a sensorless control strategy utilizing a super-twisting sliding mode observer (ST-SMO) integrated with phase-locked loop (PLL) parameter perturbation compensation. Two Linear Extended State Observers (LESOs) with distinct bandwidths are employed to estimate system disturbances, and a disturbance decoupling method is proposed to isolate perturbations specifically arising from parameter variations. A feedforward compensation mechanism, based on these parameter-induced disturbances, is introduced before the PLL loop filter. This approach corrects the phase detector zero-point at its source, ensuring that the PI regulator adjusts solely for the authentic phase difference. By circumventing complex parameter identification, this method significantly enhances the robustness and steady-state accuracy of position estimation across the entire speed range. Finally, simulation results validate the effectiveness of the proposed methodology.