Influence of Coating of PM on Eddy Currents in PM of Surface-Mounted-PM SM

Recently the rare-earth magnets NdFeB and SmCo are applied to a magnet rotor of PM motor. The conductivity of rare-earth magnet is higher compared with that of ferrite magnet. The loss due to eddy currents produced in the PM cannot be neglected, especially in high-speed applications, such as electric vehicles. In general NdFeB is coated with Ni and so on in order to prevent from corrosion. But eddy current analysis including coating of PM has not been presented. This paper presents the finite element analysis of eddy currents in coated PM of surface-mounted-PM SM.