Design and Analysis of a Spoke Type Motor With Segmented Pushing Permanent Magnet for Concentrating Air-Gap Flux Density

This paper proposes a new design of a SPOKE-type permanent magnet brushless direct current (BLDC) motor by using pushing magnet. A numerical analysis is developed to calculate the maximum value of air-gap flux density. First, the analytical model of the SPOKE-type motor was established, and Laplace equations of magnetic scalar potential and a series of boundary conditions were given. Then, the analytical expressions of magnet field strength and magnet flux density were obtained in the air gap produced by ferrite permanent magnets. The developed analytical model was obtained by solving the magnetic scalar potential. Finally, the air-gap field distribution and back-electromotive force of spoke type machine was analyzed. The analysis works for internal rotor motor topologies, and either radial or parallel magnetized permanent magnets. This paper validates results of the analytical model by finite-element analysis as well as with the experimental analysis for SPOKE-type BLDC motors.