Influence of Shaft on Post-Assembly Magnetization for V-Type IPMSMs

Post-assembly magnetization (PAM) has become a widely adopted technique in the production of permanent magnet (PM) electrical machines, offering advantages such as simplified assembly processes and reduced manufacturing costs. However, for V-type interior PM synchronous machines (IPMSMs), magnetizing the bottom regions of V-shaped PMs deep inside the rotor close to the shaft presents significant challenges due to weaker magnetizing fields in these areas. Consequently, achieving full magnetization for the PMs often requires a substantial increase in the charging voltage. This paper investigates the influence of the shaft material on the PAM process, considering the effects of eddy currents within the shaft. The impact of the shaft's electrical conductivity and magnetic permeability on the magnetizing field strength is analyzed using the magnetic equivalent circuit (MEC) model and then verified with finite element analysis (FEA). The results suggest that a proper selection of shaft material can suppress eddy currents within the shaft, strengthen the magnetizing field in hard-to-magnetize PM regions, and reduce energy consumption during PAM. Experimental tests are carried out with shafts made of different materials and validate the effectiveness of the proposed approach.