Adaptive Rotor Position-Error Compensation Scheme for PMSM Sensorless Drives Based on Low-Frequency Sinusoidal Signal Injection

Model-based sensorless control of permanent magnet synchronous machines is susceptible to significant position deviations caused by inverter nonlinearity, parameter mismatch, and digital delay, which are challenging to compensate accurately. To address this issue, an adaptive position-error compensation scheme based on low-frequency sinusoidal injection is proposed. By injecting a low-frequency sinusoidal signal into the estimated position, disturbance components containing position-error information are excited and extracted using the proposed signal demodulation method. A cost function is designed based on these disturbance components, and the gradient descent optimization method is adopted to minimize it, thereby searching for the optimal compensation value. The proposed scheme can achieve the total position-error compensation without requiring the accurate knowledge of inverter nonlinearity or motor parameters. The effectiveness of the proposed scheme is verified by experimental results.