Anti-Demagnetization and Efficiency Enhancement Strategies for Hybrid Magnet Interior Permanent Magnet Synchronous Motor

Interior permanent magnet synchronous machines (IPMSMs) are preferred for high power density and field weakening ability. The magnet inside the rotor is crucial to the reliability and motor performance. Currently, rare earth-based motors are predominantly used in electric vehicle applications. However, the problem with the rare earth magnet-based motor is that it can be demagnetized easily due to exceeding the negative value of the d-axis current and rising temperature. To create resilience to restrict the opposing flux due to negative d-axis current, modifications in the rotor core have been made to reduce the demagnetization. These anti-demagnetization of design techniques include a double V-shaped flux barrier with a notch on the q-axis, rotor core shaping along the d-axis, and holes near the pole arc region. However, a design trade-off has also been made to enhance the efficiency with these anti-demagnetization techniques. The design of proposed topologies is simulated in FEM software, and a comparison of the results of different topologies has been discussed.