Magnetization analysis of the brushless DC motor used for hybrid electric vehicle

Component magnetization and post-assembly magnetization are compared for the brushless dc motors used for hybrid electric vehicles through theoretical analysis, finite-element method (FEM) calculation, and experiment. Provided with enough magnetizing magnetomotive force (MMF), the permanent magnets can be fully magnetized both by component magnetization and post-assembly magnetization. The tested rotor surface flux densities of the component magnetization and post-assembly magnetization are consistent, and they are in good agreement with the FEM calculated values. By contrast, we prefer the post-assembly magnetization in order to overcome the problem of magnetic forces and ferrous debris during the assembly process.