A sliding mode control of discharge air temperature in automotive HVAC using nonlinear sliding surface in input-delay system

This paper describes that a sliding mode control of a discharge air temperature is applied in automotive HVAC. The sliding mode control is suggested to improve the response time and disturbance reduction in a variety of climate and vehicle conditions. Automotive HVAC system is modeled as four parts - the blower, heat exchanger, air mixing, and duct sensor transportation delay under the assumption of dry air, adiabatic process, the fully developed air mixing process. The weight factor in time delay and lag model was adapted to reduce nonlinear modeling and approximation error. Sliding mode control is better than PI control from the point of view of settling time in this system.