According to the requirements of a high-speed heat-airflow wind tunnel experimental system, a fuel supply system based on variable frequency control technology and proportional throttle valve is designed. The mathematical model of the fuel supply system under the mode of the proportional throttle valve control and the variable frequency pump control is established. Because the fuel supply system has a pure time delay and the change of working conditions can cause the problem of time-variant parameters, a fuzzy proportion integration differentiation control strategy with Smith predictor is proposed. In addition, switching between the pump control mode and the valve control mode will bring disturbances, so two undisturbed switching methods are designed. The simulation and experimental results show that the proposed control strategy can overcome effects of the pure time delay and obtain a satisfactory control performance. The two undisturbed switching control methods designed in this paper can achieve the undisturbed switching of the fuel flow-rate control.
This article describes the configuration and working principle of the high-temperature combustion system; according to the control requirements which have a wide range and high precision for fuel flow-rate of the high-temperature combustion system, a set of fuel supply system is designed based on the frequency conversion hydraulic technology and electrohydraulic proportional technique. An automatic control system with the function of field and remote control is carried out to achieve the precise supply of the fuel. The transfer function which describes the dynamic characteristic of the fuel supply system is given and the dynamic matrix control algorithm is employed to realize the high-quality control of fuel flow-rate. The experimental results show that the response time of flow-rate is about 12 s, almost no overshoot, and control accuracy within 1%. Therefore, the designed fuel supply system can meet the requirements of the hightemperature combustion system, and the designed control system has good control performance.
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.
This paper introduces the working principle of a high-temperature high-speed wind tunnel and analyzes the necessity of coordinated control of fuel flow-rate for the fuel supply system. In order to achieve a coordinated control of fuel flow-rate, a proportional integral (PI) cross-coupled algorithm is designed. Because PI parameters in PI cross-coupled algorithm are invariant, a better control effect cannot be achieved when there are time-variant parameters in system, so a fuzzy PI adaptive cross-coupled algorithm with model reference is designed. The simulation and experimental results show that the fuzzy PI adaptive cross-coupled algorithm with model reference has better control quality compared with the PI cross-coupling control algorithm.
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