Software design of program-controlled voltage divider for impact test

作者： GOZ Electric 时间：2024-05-08 09:44:48 阅读：21

    With the development of digital electronic technology, digital recorders have been widely used in high voltage shock tests. Its application not only improves work efficiency, but also improves the testing level of experiments. However, since the full-scale input voltage of the digital recorder does not exceed 100V, and in order to improve the signal-to-noise ratio during the impact test, the secondary terminal output voltage of the high-voltage divider is generally above several hundred volts, so when using a digital recorder for impact testing During the test, the input end of the instrument must be connected to a voltage divider (attenuator). In addition, the attenuation gear of the digital recorder is generally a 1-2-5 sequence change. During the test, in order to ensure that the quantitative error of the same-phase terminal of the sample is consistent under different voltages and to make the measurement error as small as possible (the waveform is displayed on the full screen), The voltage divider is required to have multiple voltage dividing ratios. In order to improve the automation of the test during the test, the voltage divider is required to have a program-controlled function. Based on this, a program-controlled voltage divider for impact testing was developed.

    The instrument monitoring software mainly completes chip initialization, GPIB interface communication, pressure dividing ratio control, and pressure dividing ratio display. GPIB interface communication realizes the reception of program control commands and the output of instrument status information through the GPIB interface.

1 Main program design

The main program includes expansion chip initialization, voltage dividing ratio display, setting initialization, instrument address identification, interface communication, interface command processing, etc.

2 Three-line contact program design

To use software to implement interface functions, you must understand how data is exchanged under the control of the three tie lines DAV, NDAC, and NRFD. The GPIB interface line is negative logic, and data exchange must be carried out according to the timing diagram of three-wire communication. During the communication process, the three-wire status is determined through software query to complete the data communication and its three-wire communication timing.

3 Performance test

4 Square wave response test

Remotely set the voltage dividing ratio of the program-controlled voltage divider through the GPIB interface, and test the square wave response waveforms of the three channels CH1, CH2, and CH3 respectively. Among them, the square wave response rise time of channel 1 is 9. 5ns, and the bandwidth BW = 350/9. 5 = 36. 8MHz. The rise time of channel 2 square wave response is 9. 9ns, and the bandwidth BW = 350/9. 9=35.4MHz. The square wave response rise time of channel 3 is 10.2ns, and the bandwidth BW = 350/10. 2 = 34. 3MHz. It can be seen from the above test that the bandwidth of the three input channels is about 35MHz, and the response waveform has no oscillation and distortion, which can meet the impact test measurement requirements.

5 Test of partial pressure ratio

The shock wave generated by TYPE481 is applied to the three input terminals of the program-controlled voltage divider, and the amplitude of the input signal is 63. 2V. The measurement results of the three channels show that the measurement error of the corresponding partial pressure ratios of the three channels is < 1%.

6 Conclusion

The developed program-controlled voltage divider meets the design requirements. Its frequency bandwidth is about 35MHz, the voltage dividing ratio error is < 1%, and the input impedance is 1MΩ/50pF. During the test, the program-controlled voltage divider responded quickly, reliably, and worked stably to program-controlled commands, and the response waveform had no distortion. Using this voltage divider for impact testing improves the measurement accuracy and automation of the test, and the voltage divider reaches a leading level.