Design and optimisation of oil injection pipe cooling structure for permanent magnet synchronous motors in hybrid electric vehicles

Abstract In recent years, with the continuous improvement of motor power density, oil cooling technology has been widely used in permanent magnet synchronous motors (PMSMs) for electric vehicles (EVs) as an efficient cooling method. A PMSM with a rated capacity of 53kW for hybrid electric vehicles (HEVs) is designed, and the motor is cooled by the oil injection pipe. In order to improve the heat dissipation efficiency of the end winding, the number of injection pipes and the structure of the nozzle are optimised, and a novel nozzle structure is proposed. By using the moving particle solution (MPS) method to simulate the fluid flow, the optimal cooling structure of the motor is determined. In addition, different from the equivalent winding model in the traditional temperature field simulation, a hairpin winding model that can more realistically reflect the geometry of the end winding is established. On this basis, the temperature field of the motor is simulated. It is verified that the cooling structure designed can effectively improve the thermal performance of the end winding.