Back Electromotive Force-Based Discrete-Time Rotor Position Bias Compensation Method for Permanent Magnet Synchronous Motors

In permanent magnet synchronous motor (PMSM) drives, the rotor position signal is critical. However, the failure of the mechanical position sensor and the position tracking error of the resolver-to-digital conversion causes position signal biases. These position biases significantly deteriorate motor drive performance, whereas there are few effective methods to handle both biases simultaneously. To uniformly and accurately compensate for these biases, a back electromotive force (back-EMF)-based discrete-time rotor position bias compensation method for PMSMs is proposed, which includes improvements in compensation accuracy and algorithm execution efficiency. In the proposed scheme, an adaptive disturbance observer with multiparameter estimation is designed to estimate the back-EMF. The proposed multiparameter estimation is designed based on the decomposed voltage vector of the current regulator. Compared with widely used recursive-least-square methods, the proposal greatly reduces the computational burden. Then, according to the rotational mode of the back-EMF in the discrete synchronous reference frame, an exactly discretized back-EMF model is established. Based on this model, a discrete-time compensation method for rotor position bias is proposed. Compared with the continuous-time back-EMF model-based method, the proposal can suppress the estimated error between actual and estimated bias, which rises with increasing motor speed. Finally, the experiments are carried out to verify the effectiveness of the proposed method.