Reynolds number based optimization on liquid cooling system for permanent magnet synchronous motor of electric vehicle

The electric motor thermal management system (TMS) is a pivotal unit for electric vehicles (EVs). To study the factors affecting cooling performance and cooling efficiency of spiral housing water jacket (HWJ), simulations were carried out on a 150 kW jacked-cooled permanent magnet synchronous motor (PMSM) with ethylene glycol & water (EGW) as coolant. The coupling between channel numbers (N) and coolant flow rate (Q) on winding average temperature (T) and pressure drop (P) were investigated focusing on the Reynolds number (Re) via analytical and numerical thermal models. The results indicated that the cooling performance was nearly the same for coolant under fully turbulent. Both the cooling performance and cooling efficiency were not conducive when N > 8, and meanwhile, N < 6 also hindered the heat extraction. Resorting to the investigation, a Re-based multi-objective optimization algorithm was put forward. Compared the optimized jacket N6Q12 (denoting 6 channels with 12 L per minute flow rate) with the sub-optimized N12Q6 at the same Re, winding average temperature T was found 6.5 deg C lower, and pressure drop P was reduced by up to 71.6 %.