This paper shows various rotor structures of interior permanent magnet synchronous moter (IPMSM) with Dy-reduced rare earth magnet. Dysprosium (Dy) is added to permanent magnet to increase the magnetic coercive force. However, Dy is so rare and expensive. A conventional model using Dy-reduced rare earth magnet cause ploblems with demagnetization. In these reasons, the rotor structures of IPMSM with Dy-reduced rare earth magnet for improvement of irreversible demagnetization without torque reduction are proposed. The presented IPMSM structures are analyzed by using finite element analysis (FEA). Finally, the proposed model which improved the demagnetization and torque characteristics was able to get approximately the same characteristics of conventional model using Dy-much rare earth magnet.
