Evaluation of microstructure, mechanical and magnetic properties of laser powder bed fused Fe-Si alloy for 3D magnetic flux motor application

Abstract

Since their high power-to-volume property, electric machines with 3D magnetic flux (3D-flux) structure are of great current interest. In them, the flux path is typically achieved by utilizing a soft magnetic composite (SMC) material to minimize the eddy current losses. Here, laser powder bed fusion (LPBF) technique is employed to manufacture a soft magnetic core (Fe-3.5 wt%Si alloy) with the following advantages: i) the (001) texture of Fe-Si alloy is well aligned with the Z direction of the 3D-flux path, which is the easiest magnetization direction in the cubic system; ii) the strength and ductility of the annealed alloy are far superior to those of SMCs. The alternating-current ring method was employed to measure the magnetic properties and a simulation of the 3D-flux electric machine was conducted. The results illustrated that the rotary torque generated with the additively manufactured alloy is 19.1% higher than that of SMCs in the weak magnetic field excited by ferrite at the 50 Hz frequency. However, it is important to note that the additively manufactured alloy also exhibited higher total iron loss in strong magnetic field and high electric frequency, indicating a need for further research to optimize the microstructure and reduce losses for medium/high frequency applications.