Study on the position identification of a Halbach array permanent magnet spherical motor

Halbach array permanent magnet (PM) spherical motor offers a number of attractive features. This paper described the structure, working principle and analytical equations of magnetic field of the Halbach array PM. Based on the magnetic field distribution and three-dimensional (3-D) magnetic field measurement, a position identification method was present. The analysis results of the positioning process show that the motor position can be determined by the rotation angles of the motor, which revolves around three reference axis of the stator. Furthermore, the coordinate of point, where magnetic field was measured, is obtained from the rotation angles. According to the magnetic field model and the rotation transformation theory, the nonlinear relationship between the measured value of magnetic flux density and the rotation angles was obtained. So by solving the nonlinear equation, the rotation angles were obtained and the motor position was identified. The validity was verified through the simulation.