Steady State Thermal Analysis of Stepper Motor, used in Automobile HVAC Blend Door Actuator

Heating ventilation and air conditioning system have gained a lot of popularity for passenger comfort in vehicles. Till now the mixing of the hot air and cold air was achieved by movement of the blend door with the help of a lever. Achieving the optimum temperature inside the cabin required movement of the blend door continuously. HVAC system helped in achieving the optimum temperature with the help of a blend door actuator. The blend door actuator continuously adjusts the amount of hot and cold air mixture, for passenger comfort. For the blend door actuator till now DC motor were being used, which used to consume more current. A feedback system was also necessary for the dc motor. But with the use of a stepper motor in the blend door actuator, many advantages could be attained. The feedback system was not required by a stepper motor and was more accurate than dc motor. The main advantage of the stepper motor was it utilized less current. As stepper motor was being proposed to be used in the blend door actuator, it was important to analyse the heat generated in the stepper motor. This paper focuses on the heat generated by the coil of the stepper motor and how the heat flows from the coil to the stator through the bobbin under natural convection condition was analysed. The model was analysed under steady state thermal condition.