Getting Started: LVTGO-VBS: Low Voltage Battery Simulator For EMC Standards & Robustness Testing

Hello, my name is David Shaw I’m here to
introduce the LVTGO-VBS, our low voltage EMC standards and robustness test unit.
The system can help you to test to many automotive standards including ISO16750, Chrysler 11979 and JLR CI265. I’m going to show you how easy it is to build and
deliver your first waveform. Later on I’m going to talk about randomising
waveforms and the many other waveform types the unit can deliver which are
common throughout automotive testing. Let’s get started. On the table here, we
have a standard lab scope, the LVTGO hardware, and a laptop running LVTest, which is our low voltage test control software. As you can see there’s
a CAN data connection between the LVTGO and the laptop, a mains supply for the LVTGO through our separate power supply LVT-PSU, and our scope is linked to the
output stage of the system. To configure our first test, we’ll need to open up the
LVTest software package. To do so simply double-click the LVTest icon on the
desktop. This firstly loads our real-time interface creation package VISUALCONNX, then the LVTest suite within that. The LVTest suite is composed of a
series of forms that you can see appearing at the base of the screen now. In this demonstration, we’ll deliver a typical cranking waveform to our device
under test. Once the program is fully loaded we’ll need to click the Run button
to enter the LVTest GUI, so let’s go ahead and do that. Before making a
selection, the GUI gives us a quick preview of the waveform we’re about to
deliver. Making a selection brings up this screen, that shows a live feed of
waveform delivery. To begin with, there’s nothing to see but since we’ve selected
our generic waveform type, testing can theoretically begin immediately. As you
can see, the LVTGO is now delivering a waveform to the device under test. Since we’ve not specified any randomisation values yet, it’s just
delivering the same waveform profile over and over. Still, within the space of
a minute we’re now subjecting the device under test to meaningful test
conditions. The LVTGO is much more powerful than this however. Its main
strength lies in the randomisation of these profiles, allowing tens, hundreds or
thousands of tests to take place close to known failure points. It does this by
breaking waveforms down into segments of time and voltage, then randomising
these values for each cycle that’s played. Let’s see how this is done. We’ll
need to head into voltage and time settings labelled U and T respectively. Let’s head into U settings for now. Here, you can specify values for each of the
points labelled on the right. In each case we’ll first select if we want the value
to be fixed or randomised. If we’re looking to randomise, we’ll enter maximum
and minimum values, and the resolution we’d like the LVTGO to use for this
randomisation, for example in units of 0.1 volts. We can do this for as
many or as few values as we like. Using our Genix technology, we can optionally
configure the output to have a fast falling edge. We can also configure
ground offset up to 2.5 volts. Once complete we can head into the T settings
menu and specify more values relating to the time these segments take to complete. For now we’ll leave these as they are. Now if we head back into the waveform
main screen and run the waveform again we can see that the elements of the profile we’ve chosen to randomise are now changing during each cycle. Now the
randomised waveform is being delivered to the device under test, represented
here by the scope. And since this randomisation is defined by an algorithm,
we can go back to any cycle of that algorithm and repeat it. If, for example,
your test procedure showed cycle 250 caused the device under test to fail,
this waveform can be quickly and easily replayed by selecting a start point of
waveform 250. After a short period of calculation, the system will resume by
playing waveform cycle 250 from the same mathematical sequence, allowing you to
investigate and confirm causes of failure. So we’ve now seen how to load
the LVTest GUI, how to select a waveform type, how to randomise waveform
parameters, how to deliver your waveform to the device
under test, and how to repeat waveform cycles, windowing in on known faults. Many thanks for watching. Join us again next time when we’ll be looking at the LVTGO range again, in more detail.

Leave a Reply

Your email address will not be published. Required fields are marked *