Impact of SMC Property on Axial-Flux Permanent Magnet Machine in Traction Applications

This paper investigates the impact of soft magnetic composite (SMC) properties on an axial flux permanent magnet machine (AFPM) employing ferrite permanent magnet (PM) in traction applications. In general, the efficiency of an AFPM increases as the iron loss of the SMC decreases. However, the torque and output power of the AFPM also decrease at higher speed above the base speed due to the decrease in magnetic permeability because, typically, when the iron loss of an SMC decreases, the permeability also decreases. In this paper, many virtual SMC materials with different iron loss and permeability are used for finite element analysis of the proposed AFPM in order to clarify the sensitivity to SMC characteristics. First, the impact of the permeability on the torque and output power is investigated because the output power is very important in traction applications. Additionally, the total energy loss of AFPMs employing various SMCs is evaluated using the WLTC driving cycle. Furthermore, accuracy of simulation is evaluated using experiments of downscaled and actual size prototypes employing some SMC materials. Finally, this paper shows the newly developed SMC materials and discusses suitable SMC properties from the perspective of efficiency and output power in traction applications.