Non-Salient PMSM Position Sensor Offset Calibration Approach in the Presence of Uncalibrated Current Sensors

Position Sensor Offset Error (PSOE) in permanent magnet synchronous machines (PMSMs) can lead to significant degradation in control performance, causing torque reduction, reduced efficiency, and compromised stability in high-precision motor drive applications. Conventional in-system calibration requires accurate current measurement implying current sensor calibration is required prior to PSOE calibration. However, the proposed method facilitates PSOE calibration without the need for proper current sensor calibration, and requires no back emf measurement reducing the manufacturing burden. The approach leverages existing field-oriented control blocks coupled to an extremum seeking controller (ESC) to accurately obtain the PSOE in the presence of current measurement error. The ESC approach is independent of motor parameters and thus eliminates an additional error source. A detailed theoretical analysis of the algorithm is presented, along with implementation considerations for real-time control systems. The effectiveness of the method is validated through experimental results, demonstrating significant improvements in performance under low-speed conditions. The results confirm the robustness and adaptability of the extremum seeking approach.