In this paper, the finite element model of the three-dimensional steady-state temperature field for a miniature water-cooled induction motor was established. The effective thermal conductivity was introduced to simplify the complex heat transfer process in the air gap. The heat losses of various parts of the motor were calculated, as well as the chassis water jacket heat exchange coefficient based on the similarity criterion of fluid. By three-dimensional finite element simulation, the three-dimensional steady-state temperature field distribution under rated load and the temperature field distribution under various flow rates were obtained. The simulation results showed that the highest temperature rising is located in the rotor, the temperature difference between the rotor core and the rotor bar is small, the highest temperature appears at the axial center of the motor's rotor bar, the temperature rising of the stator winding is higher than that of the stator yoke, the lowest temperature rising occurs at the motor case, the change of flow rate has more effects on stator yoke and motor case, little effect on stator winding and the rotor. Under turbulent flow, the decrease of the motor temperature rising is very small with the increasing of the flow velocity. Experiments were conducted on a 34V, 4kW mini-electric-vehicle-used induction motor to measure the temperature of the stator windings, the winding ends and the stator yoke department under rated load and various flow rates. The numerical simulation results are consistent with the experimental results.
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