Study of the Use of an Axial Flux Permanent Magnet Motor for Electric Coolant Pumps

Electric coolant pumps are an essential part of the cooling circuit of electric cars. The design and control of these systems have a major influence on the proper thermal management of the batteries cells. One of the most challenging issue in the development of these devices, concerns the combination of high efficiency and very large pump lifetime. Indeed, the high pressure low flow hydraulic working point imposed by electric vehicles creates an axial force on the impeller which generates friction torque and losses on the bearings.This paper deals with the study of an axial flux motor used for electric coolant pumps. The combination of axial magnetic and hydraulic forces allows the impeller to attain levitation, therefore reducing the friction losses and increasing the lifetime and the efficiency of the pump. Firstly, the motor is modelled. Secondly the hydraulic model is detailed and finally the motor efficiency is reviewed.