Second-Order Complex-Coefficient Filter PLL for Model-based Sensorless IPMSM Drives with Operation-Frequency-Adaptive Character

This paper proposed a quadrature phase-locked loop (PLL) with a second-order complex-coefficient filter (SCCF) to improve the position estimation accuracy of sensorless interior permanent magnet synchronous motor (IPMSM) drives. Due to the inverter nonlinearity and flux spatial harmonics, it exists 5th and 7th harmonics, and dc offsets in the back-electromotive force, reducing the accuracy of estimated position. For this problem, the studied SCCF-PLL can suppress the harmonics and dc offsets with the operation-frequency-adaptive character. The stability of the studied PLL are analyzed by establishing a small-signal model. Compared with the conventional PLL, the studied PLL can reduce the estimation error of the position observer effectively. The availability of the studied method is verified by the contrastive simulation results.