Thermal analysis of underwater oil-filled BLDC motor

The viscous fluid in the air gap of underwater oil-filled Brushless Direct Current (BLDC) motor introduces an additional loss component and on the other hand improves the heat transfer between the rotor and stator. Based on the heat transfer characteristic of underwater oil-filled BLDC motor, thermal analysis of the motor considering the convection of the oil in the air gap is performed by two-dimensional finite element method (FEM). The agreement between the calculation results and test results verifies the effectiveness of the computation.