Robustness testing of low voltage systems
In today’s modern electrical environments it is becoming more and more likely that the complexity of systems that include electronic controllers will experience functionality issues when the supply voltage is not as intended.
The purpose of adding more electronics to vehicles is to improve the end user experience or to reduce wiring harness. The technology underpinning this requires a level of complexity that means components such as micro-controllers, semiconductors and non-linear drive components are required to achieve this functionality.
Despite formal standards being adopted to try to dictate levels at which systems will function perfectly, this cannot realistically guarantee 100% reliability after these tests have been passed (although it certainly helps).
This is where the techniques of robustness testing can be used to gain a better understanding at a both system and component level of the system under test.
When to adopt testing standards
You will usually have to meet standards to demonstrate that your component or system meets formal requirements before you begin production deliveries. This will normally require driving your system with repetitive electrical waveforms designed to display typical worst case voltage curves.
Standards tests such as CI 230, CI260, CI 265, ISO+7637, ISO16750, DC-10615, GMW3172, GS95003-02, LV124, VW 80101, Defence Standard 61-5 (6) and many more have all been conceived to try to create ways of testing for low voltage issues.
Should you test to these standards in the early design stages of your controller or system? Yes probably, but this is not likely to window in to specific areas of susceptibility at certain slew and voltage rates.
‘Meet The Standards’ reference document
We have compiled a list of many of the automotive low voltage testing standards in a downloadable form, detailing which hardware is required to test to these standards.
This document provides a very useful reference on many of the published standards and what is required to meet these.
Electrical simulation using robustness techniques
To improve test coverage in its early stages, you have choices you can take to make issues more likely to be found. It may help to fire random electrical noise at your hardware to try to catch these areas of susceptibility. However, if you find an issue you need to be able to repeat it accurately – this is where robustness techniques come into play.
Pseudo random techniques offer improvements over traditional methods
By using pseudo random techniques around time and voltage values, you can vary both the slew rate and the voltage ranges around expected (and unexpected) areas of susceptibility, allow long duration tests to cover more interference and, when an issue is seen, each test can be repeated by recreating the same voltage profiles.
Pseudo random techniques save time when repeating failures
By using pseudo random techniques, you can play any profile in a massively long series from any point in time – so failures can be repeated much more easily and in much less time. The LVTGO-VBS system assists with this process and the LVT-PSU can extend the scope of this testing.