Accurate calculation of induced electromotive force for axial field hybrid permanent magnet memory machine

Abstract

The axial field hybrid permanent magnet memory machine (AFHPM-MM) employs a hybrid permanent magnet excitation combining NdFeB and AlNiCo, achieving high torque density and a wide flux adjustment range. A separated stator structure is adopted to enhance its antidemagnetization capability. To analyze the contributions of AlNiCo and NdFeB to the induced electromotive force (EMF) in the AFHPM-MM, a frozen permeability-based induced EMF calculation method is proposed. Theoretical analysis reveals that the conventional method exhibits substantial errors in calculating the AlNiCo-induced EMF, primarily attributed to its failure to adequately account for the dynamic magnetization characteristic discrepancies of AlNiCo under varying magnetization states. Through the analysis of magnetization variations in AlNiCo during the flux adjustment process under different magnetization states, an improved induced EMF calculation method is proposed. Comparative results indicate that, during the flux enhancement process, the average calculation error of the AlNiCo-induced EMF is reduced from 19.84% to 2.09%, whereas during the flux weakening process, the error is reduced from 3.87% to 1.67%. The proposed method achieves accurate induced EMF calculation for the AFHPM-MM.

Keywords

axial field / hybrid permanent magnet excitation / memory machine / induced electromotive force (EMF) / accurate calculation

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Funding

National Natural Science Foundation of China(52107039)

Fujian Provincial Natural Science Foundation for Youth(2021J05133)

Key Project of the National Natural Science Foundation of China(51937002)