Effects of external field orientation on permanent magnet demagnetization

This paper investigates how the orientation of the applied demagnetizing magnetomotive force (MMF) affects the demagnetization behavior of Nd-Fe-B magnets that are widely used for permanent magnet synchronous machines (PMSMs). This work designs and builds a customized test fixture that can produce a magnetic field with varying orientation and intensity to demagnetize magnet samples. A computer-controlled 2D mapping device is used to record the flux density above the test samples. The measurement results are compared with the 3D finite element analysis (FEA) simulations. The understanding and insights obtained from this work will improve the robustness of magnet design for high power density PMSMs with improved capability of withstanding demagnetization during overcurrent faults.