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This paper presents an improved approach for estimating high-resolution rotor position in permanent-magnet synchronous motor (PMSM) drives with low-resolution Hall-effect sensors. A vector-tracking position observer in conjunction with discrete Hall sensors' output signals has been proposed, which is similar to a phase-locked loop structure. It consists of a position error detector, based on the vector cross product of the unit back-electromotive-force vectors obtained from a stator electrical model, and a proportional-integral-typed controller to make the position error rapidly converge to zero. This structure does not only compensate the misalignment effect of Hall sensors but also enhance their transient operating capability. The effectiveness of the proposed approach has been verified from several experiments in a low-voltage PMSM drive for automotive applications.