Research on the Accuracy of Magnetic Angular Displacement Sensor

In this study, a magnetic rotary displacement sensor is designed that consists of a concentric magnetic ring rotor, a displacement sensor main board responsible for displacement arithmetic, an AD sampling board responsible for synchronous acquisition, six external tunnel magnetoresistance (TMR) boards, and two sets of ferrite plug-in Hall modules. In this article, the measurement errors caused by rotor dynamic eccentricity were analyzed, and a multisector complementary measurement model was established. The effectiveness of the suppression algorithm was theoretically proven, and a rotary displacement sensor angle segmentation algorithm is proposed based on three sets of magnetic field signals. The inner two circles consist of 7 pairs of poles and 11 pairs of poles of reciprocal magnetic field signals, and the decoding algorithm can be synthesized through the 12-bit mechanical angle. The mechanical angle signal synthesized in the inner circle is the reference angle signal, which is combined with the 256-pole-pair electrical angle signal of the outermost circle to subdivide the reference mechanical angle, and a high-resolution mechanical angle is obtained. Because of the synchronized sampling of the FPGA, six mechanical angles can be calculated in each cycle, and these six angles are symmetrical, so errors such as mounting or eccentricity can be reduced by averaging the six mechanical angles.