3D temperature field calculation of mine-used flame-proof integrative variable-speed system

Mine-used flame-proof variable-speed system consists of highly integrated converter and motor, and works in harsh environments. The closed internal structure of the system makes its cooling extremely important and renders the calculation of its temperature field a necessity. However, for such a system, because the cooling condition and geometric structure of the motor are not entirely symmetrical, the general symmetric model for motor temperature analysis cannot be used. In order to solve this problem, a complete three-dimensional geometric model was developed and upon which, a high quality grid model was obtained. A mathematical model of the cooling water and the flow channel was derived from the solution of coupled three-dimensional flow and heat transfer. The heat exchange model among air gap, stator and rotor was obtained using equivalent thermal conductivity coefficient, and the local energy non-conservation problem caused by the use of heat dissipation coefficient was overcome by user-defined functions. The control equations were solved with given assumptions and boundary conditions. The temperature field of the motor and the converter power module was obtained; and the flow properties of cooling water and the distribution of convection heat transfer coefficient were analyzed. Comparisons between experimental data and calculation results were done to prove the validity of the proposed method that provides the theoretical basis for the thermal design of mine-used flame-proof variable-speed system.