Design of integrated radial and dual axial-flux ferrite magnet synchronous machine

Recently, significant attention has been paid to the use of ferrite magnets in the main traction machines of electric vehicles/hybrid electric vehicles (EVs/HEVs). However, while ferrite magnets are advantageous in terms of cost, they provide poor magnetic performance in comparison to the neodymium (NdFeB) magnets used in high-performance, high-efficiency machines with high torque densities. To overcome this issue, the application of axial-flux structures (AFSs) to ferrite magnets has been proposed, and it is anticipated that the extended air gap area created when an AFS is used could compensate for their poor magnetic properties. As an additional countermeasure, we propose an integrated radial and dual axial-flux (IRDAF) structure that has one radial-flux gap and two axial-flux gaps. Evaluations performed using finite element analysis show that a machine designed with our proposed IRDAF structure would provide good performance in terms of output torque, efficiency, and irreversible demagnetization.