Lumped parameter thermal circuit method combined with temperature field and flow field analyses for temperature predictions of permanent magnets in motors
ZENG Yingyu, JIANG Xiaohua
Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
Abstract：Sintered Nd-Fe-B permanent magnets (PM) have high electrical conductivity, but eddy currents in the PMs may cause thermal demagnetization, so the temperatures of the PMs in motors must be known. A lumped parameter thermal circuit method is presented in this paper to predict the temperature rise in the PMs using an equivalent thermal circuit for the stator obtained by a temperature field analysis, and the air gap thermal resistance obtained by a computational fluid dynamics analysis including the stator slot opening. The PM temperature of a 30-kW 4-pole motor is analyzed by this method. The predictions compare well with measurement by an infrared sensor for a pulse width modulation (PWM) voltage excitation case with significant eddy current losses in the PM with less than 3.7% error in the temperature difference between the PM and the outer stator surface. The PM temperature in the motor can be well predicted by this method from the temperature of the outer stator surface.
曾颖宇, 蒋晓华. 集总参数热路结合温度场和流场的电机永磁体温升分析方法[J]. 清华大学学报（自然科学版）, 2018, 58(1): 67-74.
ZENG Yingyu, JIANG Xiaohua. Lumped parameter thermal circuit method combined with temperature field and flow field analyses for temperature predictions of permanent magnets in motors. Journal of Tsinghua University(Science and Technology), 2018, 58(1): 67-74.
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2018, Vol. 58 
