Rotor electrical conductivity and eddy current loss analysis of high-speed permanent magnet machine with a novel composite rotor

The high-temperature rise of rotor permanent magnet (PM) in high-speed PM machine (HSPMM) is one of the main bottlenecks that limits the development of HSPMM. The main reason for the increase of the PM temperature is the eddy current loss caused by high-frequency harmonics. In this study, a new type of composite magnetic material is studied, which greatly reduces the electrical conductivity of the PM and thus reduces the eddy current loss under the condition of ensuring the magnetic properties. The electrical conductivity of magnetic powder composites is calculated by introducing the improved effective medium model of the magnetic powder packing coefficient. Through the calculation of the porosity of the magnetic powder composite, the effects of the particle size, gradation and shape of the magnetic powder on the electrical conductivity of the composite were obtained. The model solves the problem of calculating the electrical conductivity of the powder structure composite rotor in eddy current loss calculation. The accuracy of the calculation is verified by the four-probe method, which provides guidance for the design of a composite rotor HSPMM.