Investigation of Axial-Flux Permanent Magnet Machine with Strap-Wire and Segmented Magnet for Logistics Electric Vehicle

Abstract

The axial-flux permanent magnet synchronous machine (AFPM), also known as disc-type machine, was first presented in the last 70s. Since then, numerous investigations have been conducted on the AFPM due to the inherently compact structure, effective thermal management and high torque density compared with conventional radial-flux permanent magnet synchronous machine (RFPM). As a result, the AFPM possesses a more compact volume to transmit the similar energy, and is promising for the emerging automobile application. In this paper, an AFPM is designed and optimized for substituting the conventional RFPM in logistic electric vehicle (EV) in order to minimize the traction system volume. It is revealed that the AFPM exhibits significantly smaller volume and weight to obtain the same output capability. This paper mainly introduces three aspects of the AFPM: topology selection and parametric design, manufacturing techniques, and final optimization results analysis. With strap-wire design and stamping techniques to obtain a higher slot filling factor, the AFPM prototype is fabricated and tested for validation. It is demonstrated that the copper wire filling ratio increased from 78% to 88%, and the length of iron core has decreased from 180mm to 99mm compared with conventional RFPM. The analysis, simulation, and experiment validate the feasibility of AFPM for substituting conventional RFPM in logistics EV.