Modeling and Analysis of the Giant Magneto Resistance Sensor Error in Rotor Position of PMSM

Permanent Magnet Synchronous Machines (PMSM), are frequently used as traction motors and powertrains. To achieve precise speed and torque control, accurate rotor speed and position information are essential, which requires the use of rotor angular position sensors. For the advantages of small size and low cost, the giant magnetoresistance (GMR) sensor is a novel rotor position detection solution. Unfortunately, the accuracy of GMR sensors highly depends on the installation and magnetic field. To investigate the mechanism between the angular position error and mechanical installation error, the installation mathematical model in 2D space is derived. The mathematical model transformed the rotating magnetic field in the sensor coordination system into a stationary field in the magnetic coordination system. Based on this model, a 3D finite element simulation model is built in Ansys/Maxwell on which the different installation errors are compared. The results show that the misaligning of the magnetic and the shaft will introduce the second-order harmonic in the angular position signal. The simulation results also validated that increasing the gap between the GMR sensor and the magnetic can reduce the error. The experimental results validated the correction of 3D modeling approach and position error mechanism.