Reasearch On The Control System Of The High-power Arc Heater System In Serial-parallel Operation

Plasma arc wind tunnel is mainly used to simulate environment of high temperature and high pressure during aerocraft reentry flight, and also used to evaluate system performance such as heat resistant function and aerodynamic configuration of aerocraft. As the core component of plasma arc tunnel, arc heater plays an important role on the testing capability of the tunnel. With the development of our country’s aerospace industry, the testing capability of plasma arc tunnel has faced higher demands, and therefore enhancing power level has been put on the agenda.Firstly, the characters of the plasma arc load are researched in the paper. To operate steadily, there must be the "drooping" external characteristic because of the negative impedance current-voltage characters of the plasma arc load. The saturable inductor is mainly used in early power supply of arc heater to regulate voltage and it doesn’t work well in some aspects such as regulating range of voltage, power factor and automation. The rectifier power supply with thyristor regulating voltage is widely used in modern arc heater power system. The power supply system of this paper adopts the circuit topology of6phase-shifted transformers connected with rectifier bridges which have a difference of10°. The principle of serial-parallel operation with rectifier bridges and different amount of energy in these operation modes is firstly discussed. The method using digital PI controller to get constant current output performance is adopted. Then the closed-loop and open-loop operation together with harmonic pollution of the power system are analyzed by Matlab/Simulink for simulation.On these foundations, a research platform of power supply is built. SIMADYN D controller is used in the control system. The hardware configuration and control theory of SIMADYN D controller and its peripheral equipment in detail are introduced, and step7software is used to program with CFC language. At last, experiment is executed and dynamic response and current-sharing are analysized with waveform. Experimental results indicate that this power has fast dynamic response and good current-sharing feature. It demonstrates the effectiveness of digital PI control algorithm.