High-Precision Speed and Position Estimation Based on Hall Vector Frequency Tracking for PMSM With Bipolar Hall-Effect Sensors

Because of the low cost and the convenient installation, bipolar Hall-effect sensors are commonly applied to permanent magnet synchronous motors. Generally, speed and position are estimated inaccurately due to the installation error of the sensors. This paper addresses two key challenges on improving the estimation precision: 1) proposing the coordinate transformation to get the Hall rotary vector and 2) designing the Hall vector frequency tracking method to estimate the speed and position. First, the Hall vector which is related to the position is obtained by the coordinate transformation. Second, the synchronous frequency tracking filter (SFTF) is used to extract the fundamental waves which are sine function and cosine function of the position from the two orthogonal components of the Hall vector. The SFTF can eliminate the high-frequency interferences. Third, the arctan function is used to calculate the speed and position with extracted fundamental waves. The proposed method can improve estimation precision and reduce estimated error related to the inaccurate installation of Hall-effect sensors, which is parameter-independent and implemented easily. The effectiveness was verified by the experimental results on a turbo molecular pump.