Analysis on demagnetization characteristics of spoke configured Interior Permanent Magnet rotors

Abstract

Electric vehicles require compact and energy efficient motors with wider operating speed region. Interior Permanent Magnet motors with high saliency ratio are found to be suitable for such applications. However, these motor designs have an intrinsic risk of irreversible demagnetization of the magnets. To maintain air gap flux density more than the remnant flux density of the magnets placed in spoke configuration is preferred. However, with this arrangement magnets are more vulnerable to demagnetization. An investigation is made to understand the reasons behind this aspect. For this purpose rotors with different number of poles are considered and finite element based simulations are carried out.