Abstract
In this paper we aim to analyze the heat transfer of a stepper motor in frameless configuration under space conditions. Several models with different boundary conditions and different values of emissivity were calculated. A thermal model for challenging environmental conditions, with thermal insulation boundary conditions on stator is presented. Inside the motor subassemblies, the heat transfer will be made through conduction and between the motor and the environment by radiation. Using numerical analysis, it will be possible to determine the moment when the winding temperature reaches the maximum value allowed for the stepper motor in accord with the Technical Specification, in space conditions.