Thermomagnetic Cooling for High Power Density Electrical Machines

In this paper, the ferrofluid cooling has been proposed to improve the stator end-winding cooling. Compared with conventional air cooling and liquid cooling, it is found that significant temperature reduction can be achieved when the ferrofluid cooling is employed. This is because the ferrofluid material improves the heat path from the end-winding to the housing (with water jacket). In order to calculate the temperature within the electrical machines with ferrofluid cooling, a 3-D Multiphysics finite element model (using COMSOL software package) is developed which separates the stator and rotor end-spaces. In addition, the magnetic body force of the ferrofluid is derived according to the method detailed in [1]. Furthermore, the cooling channels in the water jacket around the housing has been redesigned to maximize the cooling effect achieved by the ferrofluid cooling. By comparing the ferrofluid cooling against other cooling methods, it is found that the ferrofluid cooling has a better thermal dissipation capability, especially at higher loading and higher magnetic field. The simulation results have shown that the end-winding temperature can be reduced by about 20°C @ 30Arms and 120°C @ 50Arms.