Analysis and Design of an Axial Flux Permanent Magnet Motor for in-Wheel System Using a Novel Analytical Method Combined With a Numerical Method

Byung-Oh Tak,Jongsuk Ro

doi:10.1109/access.2020.3036666

Byung-Oh Tak, Jongsuk Ro

Open Access

https://doi.org/10.1109/access.2020.3036666

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Abstract

Recently, a motor for an in-wheel system-which is advantageous when applied to electric vehicles and self-driving systems-has received much attention. In this paper, we propose an analysis and design method that can be used for an in-wheel motor. In-wheel motors require high torque density and a compact form factor to be wheel-mounted. To meet these requirements, an axial flux permanent magnet motor is proposed for the in-wheel system. The end-winding length of the coil is a key factor to be considered in this design. Hence, we propose a novel method to study the end-winding length. Due to the structural characteristics of an axial flux permanent magnet motor, a three-dimensional finite element analysis, which requires much time and expense, is essential. To solve this problem, we propose a novel analytical method combined with finite element analysis to mitigate the time and cost factors in the development of the axial flux permanent magnet motor. The magnetic saturation and the slot opening effect, which are considered during the analysis and design phase, are extremely difficult to analyze due to their nonlinearity. Therefore, a novel analytical method and algorithm, which can consider nonlinear effects, such as the magnetic saturation and slot opening, is proposed. The usefulness of the proposed analysis and design method and the axial flux permanent magnet motor for an in-wheel system were verified via 3D finite element analysis using a commercial simulation tool (JMAG).

Highlights

In recent years, the electric vehicle market has been rapidly growing in keeping up with global trends—as advanced countries adopt eco-friendly policies due to climate change, environmental pollution, and the depletion of fossil fuels [1], [2]
The available space for an electric motor in an in-wheel system is limited by the wheel size because the motor is installed inside the wheel itself
In this paper, considering these constraints, a flow chart of the design and analysis process of the motor for an in-wheel system is proposed in three stages: fundamental design of the motor, no-load magnetic field

Summary

INTRODUCTION

The electric vehicle market has been rapidly growing in keeping up with global trends—as advanced countries adopt eco-friendly policies due to climate change, environmental pollution, and the depletion of fossil fuels [1], [2]. FEA is used to analyze the characteristics of electric machines, and it offers high accuracy, it consumes an enormous amount of time In this stage, the no-load magnetic field analytical method applicable to AFPM motors, yielding a faster analysis time compared to FEA, is proposed. NO-LOAD MAGNETIC FIELD ANALYSIS USING PROPOSED QUASI-3D MEC METHOD The MEC method is used to analyze the characteristics of the model by simplifying the structure of the motor to be designed Using this method, the average air-gap magnetic flux density of the target model can be obtained. Calculation of stator core permeability of slotless motor The core magnetic flux density of the slotless motor is obtained using the air-gap magnetic flux density obtained through the MEC analysis method proposed in Step 6.

C Y2 jx2

CONCLUSIONS

FEA of the designed motor