Estimation of Magnetization State of Locally Demagnetized Permanent Magnet Using Pinching-Type Sigmoid-Function- Based Gradient Method (P-SiGrad)

The demand for permanent magnet synchronous motors (PMSMs) in automotive applications is intensifying with the growth of the electrification industry. To improve the manufacturing quality of PMSMs, it is essential to estimate the magnetization state inside permanent magnets (PMs) during the early design stage. Therefore, a method called SiGrad has been proposed to numerically estimate the magnetization distribution using the magnetic flux density measured around PMs. However, its accuracy in estimating inhomogeneous distribution with a demagnetized region is suboptimal. In this study, to improve the estimation accuracy of SiGrad with respect to the magnetization state of a PM with inhomogeneous magnetization, pinching-type SiGrad (P-SiGrad) is introduced.