A study of cooling coefficient of the brushless DC motor for car air conditioner

The cooling the DC blushless motors in car air conditioning compressors is peculiar in that it involves much higher ambient temperature than the case of the room air conditioning use. The temperature at the magnet pieces embedded in the rotors affects the motor performance in a considerable degree. The operating temperature sometimes urges design improvement under the severest operating condition. This study proposes the use of a non-working compressor model to evaluate the effect of heat transfer from the ambient through the shaft supporting housings to the magnet pieces, and will give a guide for the thermal design in the related components.