Electromagnetic and mechanical analyses of less-rare-earth interior permanent-magnet synchronous machine used for electric vehicles

In recent years, as the price of rare-earth permanent magnet fluctuates dramatically, the less-rare-earth interior permanent-magnet synchronous machines (LRE- IPMSMs) used for electric vehicles (EVs) have received more and more attentions. LRE-IPMSMs combine the features of high power density in permanent-magnet synchronous machine (PMSM) and low cost in synchronous reluctance machine (SynRM), which are promising candidates for traction motors in EVs. This paper investigates the electromagnetic performances of a 70kW LRE-IPMSM with the rotor structure of two-layer flux barrier. As a narrow bridge width can provide more torque but impairs the machine mechanical strength, the stress distribution of LRE-IPMSMs is investigated. The effects of widening the bridge and radial rib on reducing maximum stress are analyzed and compared.