Dynamic Simulation of PID Control in Transcritical CO2 Automobile Air Conditioning System

A GT-SUITE simulation software is used to establish a transcritical CO2 air conditioning dynamic simulation model and to find efficient control logic of automobile air conditioning. The opening of throttle, compressor speed and fan speed are taken as controlled parameter; the discharge pressure supply air temperature and cabin temperature are taken as target parameter. The influence of the startup sequence and delay time on the dynamic response performance is studied. In addition, the dynamic control response characteristics under variable ambient temperature and vehicle speeds are explored. Results and comparisons with other sequences show that proper start sequence improves dynamic response performance, and the sequence with discharge pressure-supply air temperature-cabin temperature lead the stabilization times of the discharge pressure and the air temperature to be shortened by 75% and 38.9%, respectively; and the ranges of opening of throttle, compressor speed, fan speed reduced by 85%, 50% and 63.3%, respectively. When the three PID controllers delay their start time at 40 s successively, the range of the compressor and fan speeds are reduced by 50% and 63.3%, that is delayed start control logic improves the stability of the control system. The PID control response is timely and the real-time values of the control target parameters do not have any fluctuation during the changes of ambient temperature and vehicle speed. Therefore, the proposed control method is efficient and stable, and it could provide important reference for the control design of actual air conditioning project. © 2020, Editorial Office of Journal of Xi'an Jiaotong University. All right reserved.