Fast Computation of the Performance of Lunar Rover Drive Motor with Skewed Stator Slots Based on 2D FEM

In order to study the performance of rare earth PM brushless DC motor with skewed stator slots for lunar rover driving wheel at extreme temperatures of lunar surface rapidly and accurately, a computational method based on 2D FEM was proposed. The skewed motor was equivalent to a certain number of straight slot motor units in series and the mathematical expression of calculation accuracy was deduced. In order to make the winding current of motor units in the same slot equal, a circuit with ideal current source was proposed to couple with the geometric model in 2D FEM. No-load back-EMF and electromagnetic torque were calculated for the prototype and the calculation accuracy was estimated according to the spectra of air-gap flux density at different relative positions of the stator and rotor in axial direction of the skewed motor. The proposed method is simpler and much more timesaving than 3D FEM. The calculated results closely match those of 3D FEM with the relative error less than 3.7%. The effectiveness of the method is verified by comparing with experimental results of multiple prototypes and the absolute error is less than 0.014Nm.