[Objective] In-wheel motors have compact space and harsh heat dissipation conditions
and the interior permanent magnets are highly susceptible to irreversible demagnetization under high temperature and large armature current surges
which seriously threatens the reliability and performance of the motors. To address this issue
this study designs a new type of FeCo-based combined magnetic pole to improve the anti-demagnetization ability and comprehensive electromagnetic performance of in-wheel motors. [Methods] Firstly
the effects of different temperatures and armature currents on the demagnetization characteristics of motor parmanent magnet were systematically analyzed
and the easily demagnetized area of permanent magnet was determined. Then
a new type of high coercivity FeCo-based material was used to replace the traditional NdFeB in the easily demagnetized area to form a combined magnetic pole. The effects of different combination ratios of FeCo-based and NdFeB in the combined magnetic pole on the electromagnetic performance were investigated through simulation
and the optimal combination ratio of FeCo-based and NdFeB was determined. Finally
the electromagnetic performance of single magnetic pole motor and combined magnetic pole motor was compared and analyzed. [Results] The motor with combined magnetic pole performed better in various aspects such as rated torque
peak torque and efficiency. At an operating temperature of 110 ℃
the rated torque of the combined magnetic pole motor increased by 4 N·m
peak torque increased by 7 N·m
and maximum efficiency increased by 0.4% compared to the single magnetic pole motor. At a high temperature of 160 ℃
the rated torque of the combined magnetic pole motor increased by 8 N·m
torque fluctuation decreased by 0.8%
and peak torque increased by 14 N·m compared to the single magnetic pole motor. At peak conditions
the critical demagnetization temperature of the combined magnetic pole was 15 ℃ higher than that of the single pole motor. [Conclusion] The designed new type of FeCo-based combined magnetic pole effectively enhances the anti-demagnetization ability of the motor under high temperature and high current operating conditions
and significantly improves the comprehensive electromagnetic performance of the motor
providing an effective technical approach to solve the problem of easy demagnetization of in-wheel motors at high temperatures.