Study On Failure Test Technology Of Digital Control Circuit In Transient Electromagnetic Environment

The stability and reliability of digital control circuit operation under transient electromagnetic environment are very important to the overall operation of the system.And digital control circuit is extremely sensitive to complex electromagnetic environment,especially transient electromagnetic pulse environment,so ensuring better immunity in transient environment is one of the key research issues of experts and scholars in recent years.In this paper,the following researches are carried out for the immunity test technology of digital control circuit under transient electromagnetic environment:First of all,three kinds of interference injection devices,continuous wave,double exponential pulse wave and rectangular pulse wave are designed by combining simulation,design and experimental verification methods,and the problem of how to apply the interference signal to the chip pins of the digital control circuit is solved.Based on the principle analysis of the interference injection device,an equivalent model is established in ADS,the capacitance parameters in the coupling network are simulated,the influence of the parasitic parameters of the capacitance on the output waveform is analyzed,and the coupling capacitance parameters are determined.The performance of the designed interference injection device is verified by experiments.The test results show that for the continuous wave interference injection device,the response amplitude flatness in the frequency domain from 100 MHz to 1GHz is less than0.5d B;for the interference injection device of high voltage double exponential pulse wave,the half pulse width time of the double exponential pulse after passing through the pulse injection device will be slightly reduced;for the rectangular pulse wave interference injection device,the output waveform will have a certain reverse overshoot,and the output waveform is slightly larger than the amplitude of the injected waveform.decreased,but its rising edge time and halfpulse width are basically unchanged.Secondly,a photoelectric conversion device is designed that can meet the requirements of long-distance low-loss transmission signal,which is used to detect the change of the output signal of the interfered circuit pin,which solves the problem that the oscilloscope and other test equipment may be affected by the environment in the transient electromagnetic environment.The problem of interference is realized,and the accurate detection of the output signal and waveform of the circuit pin is realized.The light-emitting circuit,light-receiving circuit,switching circuit and power supply circuit for processing digital signals are designed.In order to compensate for the attenuation of the signal during transmission,a signal amplifier circuit is designed.The performance test shows that the 3d B bandwidth of the photoelectric conversion device can be from 1MHz to 1GHz,the sensitivity is about-70 d Bm,and the dynamic range is about 73 d B.Finally,the anti-interference test of the digital control circuit is carried out through the device designed above,and the anti-interference tests of the double exponential pulse wave,the periodic rectangular pulse wave,the pulse modulated wave and the continuous wave are respectively carried out on the digital control circuit.The immunity test of the double exponential pulse wave has obtained the relationship between the pulse amplitude and the failure of the digital control circuit.The test results show that the immunity of the power pin to the double exponential pulse interference is better than that of the IO pin,and When the voltage amplitude of the double exponential pulse reaches more than 1000 V,it will have a greater impact on the IO pin and the power supply pin,especially the IO pin has irreversible damage.For the immunity test of periodic rectangular pulse wave,the relationship between the rising edge time of the pulse and the failure of the digital control circuit is obtained.The test results show that the interference will have a significant impact on the IO pin of the digital control circuit chip.When the rising edge time of the pulse is less than 280 ns,the IO pin will generate a logic inversion.For the power supply pin,although there is no obvious failure phenomenon,it will cause the output voltage to be unstable.For the pulse modulated wave and continuous wave,the relationship between the frequency and the injected power and the failure of the digital control circuit is obtained.The test results show that the power pin is most sensitive to the frequency of the interference signal around 300-400 MHz,and the IO pin is the most sensitive to the RF frequency.Interfering signal frequencies between 100 MHz and 400 MHz are the most sensitive.