Analysis of Interior Permanent Magnet Synchronous Motor according to Winding Method

Abstract

In this paper, the hairpin method is applied to an Electric Vehicle (EV) driving motor with a stator winding designed with a round copper wire. The hairpin method is a method to secure a high space factor by using round copper wire instead of round copper wire for the stator winding. The applicable model is a 300kW Interior Permanent Magnet Synchronous Motor (IPMSM), and the cooling method is water cooling. The current density has a proportional relationship with the thermal characteristics, and in the case of a round copper wire, a method of lowering the current density by using the stator winding as a stranded wire is used. However, when the hairpin method is applied, it is expected that the current density will be low as the area of the conductor is increased, but in reality, this is not the case in most cases. Accordingly, thermal characteristics are supplemented by using oil cooling rather than water cooling as the cooling method. However, in this paper, the thermal characteristic change is analyzed using the same cooling method. The process of applying the hairpin method from the round copper wire method is sequentially described, and changes in the main electromagnetic characteristics of the motor are compared and analyzed. Additionally, by selecting an operating point, the thermal characteristics are also analyzed. In this study, the analysis is based on the finite element method (FEM)-based electromagnetic simulation.