氢氧发动机紧急关机测试的多路信号源设计

Design of Multi-Channel Signal Source for Emergency Shutdown Test of LH2/LOX Rocket Engine

氢氧火箭发动机试验准备过程中,要对发动机紧急关机程序进行测试。测试时需要使用频率、毫伏级电压和高/低电平等多种信号源,模拟加载发动机异常状态下的传感器信号。为解决传统方法需要设备多、操作烦琐的问题,设计了一台可自动同时输出12路紧急关机测试信号的信号源。使用DDS芯片AD9851输出频率可可的正弦波信号;使用DAC8554输出精确电压小信号,并利用精密电阻分压获得了更高的分辨力和更低的输出电压;使用三极管输出高/低电平信号。以STM32为主控制器,结合串口屏设计了输出控制和人机交互界面程序。经校准,信号源输出频率信号的精度为0.02%,电压小信号设置精准度不超过0.2 mV,适用于多种型号氢氧发动机试验,可有效提高试验准备效率和自动化水平。

In the preparation of LH2/LOX rocket engine test,it is important to test the emergency shutdown procedure of the engine.During the test,a variety of signal sources such as frequency,millivolt voltage and high/low level are needed to simulate the sensor signal under abnormal conditions of the loaded engine.In order to solve the problems that the traditional method requires more equipment and the operation is complicated,a signal source that can automatically output 12 channels of emergency shutdown test signals at the same time is designed.DDS chip AD9851 was used to output sine wave signal with adjustable frequency.DAC8554 was used to output the precise voltage small signal,and precise resistance partial voltage was used to obtain higher resolution and lower output voltage.Triodes were used to output high/low level signal.With STM32 as the main controller,combined with the serial port screen including the channel calibration program,the output control and human-computer interface program were designed.After calibration,the accuracy of the output frequency signal of the signal source is 0.02%,and the setting accuracy of the small voltage signal is not more than 0.2 mV.It can be applied to the test of various types of LH2/LOX engines,and can effectively improve the efficiency of test preparation and the level of automation.