Rotor Position Estimation Using Harmonic-Decomposition Complex-Coefficient Filter-Based PLL for PMSM With Switch Hall-Effect Sensors

Three Hall-effect sensors can be used to estimate the continuous rotor position of permanent magnet synchronous motors (PMSMs) at a low cost. However, available position estimation methods generally require motor model parameters or have a phase offset. For this purpose, this article proposes a harmonic-decomposition complex-coefficient filter-based phase-locked loop (HD-CCF-PLL) structure that is independent of motor parameters and has a near-zero phase offset. First, the triggering principle of Hall-effect sensors is introduced, and the effect of Hall position error on current harmonics and torque ripples is analyzed. Then, coordinate transformation and harmonic decomposition methods are presented for three Hall-effect sensors. However, there is a limit to the number of times a microcontroller can perform real-time harmonic decomposition. The decomposed Hall position vector still contains high-order harmonics, which reduces position estimation accuracy. Therefore, a CCF-PLL technique is employed to filter out these harmonics and estimate the rotor position. An efficient method of CCF-PLL online parameter self-adjustment is also provided for adapting to different speeds. Finally, the effectiveness of the proposed method is verified by detailed experiments. The results show that the proposed method can effectively filter out the harmonics in the Hall position vector with higher position estimation accuracy, fewer current total current harmonic distortion, and a smaller torque ripple than the existing method.