A flux barrier cooling for traction motors in hybrid drives

This paper presents a detailed cooling approach for traction motors which are mounted in hybrid electric vehicle (HEV) or battery electric vehicle (BEV). There are specific guidelines for the design of a traction motor in hybrid drives, such as the small and restricted packing area and on the other side, the need for a high power - and torque - density. For this vehicle powertrain application the Permanent magnet synchronous machines (PMSM) is a common choice, because of a high power density, a high efficiency and a small package. Nevertheless, this machine type has several drawbacks on the thermal design side, such as, it is susceptible to suffer insulations failures of coils and demagnetization of magnets under severe thermal condition. Therefore, a goal for every thermal optimization is to increase the cooling and generate proper heat dissipation to the cooling fluid. This paper presents a PMSM with flux barriers in the stator and a detailed view on the cooling system. The cooling system the flux barriers to increase the cooling effect and therefore, overcome the drawbacks of the PMSM. A simulation of the fluid flow is presented by a finite volume Computational Fluid Dynamic (CFD) model with ANSYS Fluent. This is a useful tool to analyze the cooling flow in a traction motor with regard to fluid velocity, flow quantity and pressure drop. In addition, a Prototype of the cooling system is tested on a test bench to verify the results.