Magnetic field computation for high speed surface mounted permanent magnet machine with parallelly magnetized magnet segments

Due to some limitations of permanent-magnet production and magnetizing technology, it is difficult to fabricate the large poles of high power surface-mounted permanent-magnet machines by using integral magnet. One simple solving scheme is that each large pole could be formed by several parallelly magnetized magnet segments. For the PM machines with such magnets configuration, this paper gives a detailed analytical solution of magnetic field distributions in the machine. The analytical model is built in two-dimensional polar coordinates and involves the solving of magnetic field governing equations, i.e., Poisson's equation in magnet region and Laplace's equation in air gap region. The deduced analytical solution is compared with finite element method, and the results show that they have a great agreement. This analytical solution is able to compute the magnetic fields in magnets and air gap with high accuracy and efficiency, which provides a useful tool for preliminary design and optimization of the surface-mounted permanent-magnet machines with parallelly magnetized magnet segments.