Hybrid Magnet Configuration to Reduce the Content of Rare Earth Elements in a PM-SynRel Machine

An electric drive with reduced content of rare earth magnets is sought after by the manufacturers of electric vehicles (EVs). A ferrite based permanent magnet assisted synchronous reluctance (PM-SynRel) machine has emerged as a viable alternative to curtail the dependence on NdFeB PM. However, inadequate torque density and demagnetization withstand capability of these machines prevent them from being used in EVs. This paper aims at identifying topologies of PM-SynRel machine which exhibits adequate torque density and demagnetization withstand capability with reduced rare earth content. Tandem arrangement of NdFeB and ferrite PMs in the flux barriers reduces rare earth content and improves demagnetization withstand capability without a significant change in output torque. Based on this, NdFeB-Ferrite-NdFeB (NFN) and FNN topologies of PM-SynRel machine are deduced as favourable choices for the EV sector. Finally, a multiphysics optimization is implemented to ascertain the performance of both NFN and FNN topologies.