Compound sliding-mode predictive control for a temperature system of high-speed heat-airflow wind tunnel

The mathematical model of the temperature system under the mode of the proportional throttle valve control and the variable frequency pump control is established, respectively. A compound control strategy that consists of a compensation controller and a sliding-mode predictive feedback controller is designed. The compensation controller, which takes the change of the wind speed as parameter, is used to eliminate the impact on the system caused by the change of the working conditions (wind speed); the sliding-mode predictive feedback controller is used to solve the problems in the system such as time delay, time-varying parameters and disturbance. In order to solve the problem of temperature disturbance caused by the mode switch between pump control and valve control and the oil-rich combustion phenomenon in the high-temperature case, a method takes the ramp signal in which the slope is adjustable as a temperature setting signal is proposed. The experimental results show that the designed strategy obtains a satisfactory control performance and can achieve the temperature control with fast response time and no overshoot. In addition, it takes the ramp signal in which the slope is adjustable as the temperature setting signal can achieve the undisturbed switching control of the temperature and prevent the oil-rich combustion effectively.