Dynamic modeling of an automotive air conditioning system and an auto tuned PID controller using extremum seeking algorithm

This paper presents the application of Extremum Seeking (ES) algorithm in auto tuning of an incremental proportional-integral-derivative (PID) controller in order to achieve optimal cabin temperature control of an automotive air conditioning (AAC) model. A mathematical nonlinear model of an AAC system with variable speed compressor is first developed. The AAC model consists of a condenser, evaporator, thermal expansion valve, variable speed compressor driven by a direct current (DC) motor and a vehicle cabin. The ES algorithm is introduced and used to tune the parameters of the PID controller via iterative step function simulation. Finally, step response tests show that PID controller delivers better performance after being tuned by ES algorithm.