Structure and heat management of  the motors developed in Okayama vehicle engineering project for the next EV

Abstract

　In this project, we developed outer rotor type in-wheel motor. It was confirmed that there was no problem in the structure of motor by water resistance test, dust test and salt spray test. Due to the effect of adding fins on the motor case and reducing the current density, it can be driven at 15 kW without cooling for 1 hour on the motor bench, the temperature rise was less than 110 °C. As a result, the heat resistant class of the motor is classified H class in TRIAS. It was confirmed that there was practicality even without cooling by driving tests using vehicles equipped with developed motors on expressways and uphill gradients.