Read how add2 helped Changan Automobile to increase the electrical robustness of its control systems during sub-system and full vehicle testing. By providing enabling technology that can replicate a lifetime of battery use in the lab and hence test ECM robustness, add2 allowed Changan to discover, replicate and resolve control issues. This allowed it to safeguard the high level of product quality that its customers expect. 

The problem

As consumer demand drives ever more complex vehicle functionality, so the complexity of on-board electronics increases. While the automotive industry progresses through driver assistance, V2X and ultimately full automation, there is an increasing volume of control systems within vehicles; all of which must interact consistently. When exposed to voltage perturbations, these controllers can experience issues both on an individual and a network level, as controllers go into standby and wake up. A typical road car may contain in excess of 100 of these ECMs.

There are a large number of issues that can occur during prototype testing and later on the road; caused by elements such as the battery charge levels, networked load impedance, incremental degradation of wiring harnesses, caused by temperature excursions, humidity changes and more through a vehicle’s operating life. Therefore, it can be said that there are many possible causes of control issues, many of which are interlinked in nature. And so, pinpointing why any failure has happened can be a laborious and time-consuming task.

Low Voltage EMC Standards & Robustness Tester RangeThis was the situation at Changan, as control issues were discovered during test track testing as part of the prototyping phase. To discover, replicate and fix the cause of the issue via traditional methods would require a significant manual process, many hours of specialist test track driving and a helping hand from the weather. The time it would take to resolve the fault would have had an impact on the delivery times for subsequent development phases and take up the time of skilled engineers, not to mention the not inconsiderable expense of test track time.

As part of the development process for a new powertrain system, vehicles are subjected to a set test program in a dedicated track environment in China, carrying out one of the test programmes during the winter months where the ambient temperature is low.

Vincent Garvey, Chief Engineer at Changan, explains.

“Random interrupts were occurring during the course of the development work at specific times during the day, or at points such as where the vehicle had been left standing for a considerable amount of time.

The project was complex, and spanned multiple continents with personnel working together, which made it difficult to find the source of the fault.”

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The solution

Changan discovered that the root cause of the interrupts was the environmental conditions experienced by the entire electrical system. It investigated and identified the LVTGO-VBS as appropriate equipment to simulate the voltage perturbations brought about by the effects of cold weather on the vehicle battery.

The LVTGO-VBS is a low voltage battery simulation test unit for robustness testing. It sits in place of the vehicle battery and delivers voltage dropout waveforms to meet and exceed the requirements of EMC Standards. Providing this unit enabled Changan to conduct in-depth and detailed testing on the test board, in a more controlled environment, in order to track down the intermittent issues it was experiencing.

“Once we had identified the LVTGO-VBS as the appropriate test equipment solution, we were able to do some detailed confidence testing of our systems prior to then going to full certification testing. In this instance the LVTGO-VBS showed us that the software wasn’t responding in the way that we anticipated, and that then enabled us to identify that and go back and address it.” Mr Garvey confirms.

Voltage perturbation waveforms possible using LVTGO“We’re able to record the activities of our electrical systems, in terms of the electrical supply our vehicles are given in a full vehicle environment, by playing it through the LVTGO-VBS. This gives us greater confidence that we won’t suffer from some of the issues we have experienced previously.”

The LVTGO-VBS allowed Changan to ensure their electrical systems met and exceeded the requirements of ISO 16750. By generating randomised yet repeatable waveforms using a process known as pseudo-randomisation, it allowed engineers to find specific issues, confirm them as the cause through repetition of key test sequences, and then work on resolving them. The LVTGO-VBS also allows its users to replay captured battery voltage data and then replay this to systems under test.

“What was key to us was not only were we able to capture what was happening using existing equipment on the electrical system in terms of the power supply, but we were able to replay that faithfully through the LVTGO-VBS, meaning that we were able to replicate what was happening on the vehicle electrical supply through the LVTGO-VBS on our control system.”

 

Changan logo“We’re really impressed with add2’s responsiveness and the support they offered. Their willingness to take on suggestions from us was also very welcome, instead of offering a take it or leave it approach.”

Vincent Garvey, Chief Engineer, Changan. 

 

Conclusion

Mr Garvey is happy to report that the LVTGO-VBS is now used as a matter of course at this stage of electrical systems engineering.

“As a part of our development phase we now have a set time where we subject systems to the test that we’re able to deploy using the unit. Although the purchase was in relation to the individual programme, it’s now become structure-based.”

The LVTGO-VBS unit is currently in active use across a range of automotive OEMs and suppliers, providing detailed testing for ECMs in the development stage.

More information on the LVTGO-VBS is available here