Selective Self-Calibration of Current Sensor Offset in PMSM Drives

Permanent Magnet Synchronous Machines (PMSMs) are a popular choice in modern applications due to their high efficiency and power density. Field-Oriented Controller (FOC) for PMSMs relies on accurate current measurements to ensure stable torque control and overall system performance. However, current sensor offset (CSO) is a common and critical issue in PMSM drives, leading to distorted current feedback, torque oscillations, and performance degradation. In modern drives, a calibration phase is required to eliminate current sensor offset. In this paper, a real-time, model-free calibration technique based on Extremum Seeking Control (ESC) is proposed to mitigate the effects of CSO in a particular phase. The approach utilizes a sinusoidal perturbation and the integral of the zero-sequence current as a performance metric to adaptively cancel the offset error without requiring motor parameters. Simulation and experimental results validate the effectiveness of the method under various fault scenarios, and operating conditions. The proposed technique demonstrates strong self-healing capability and robustness, making it well-suited for PMSM drive systems.