Can anyone tell me what gives rise to the specified maximum operating voltage (58V) on the Regen Clamp? e.g. component spec, not tested above this level, some margin away from a known failure value.
Is this the absolute max, or a recommended max which has some (small) headroom?
Hi!
58V is a recommended continuous max. Plenty of headroom realistically. Main “actual” limits:
- TVS diode (Nexperia PTVS58VP1UP) is specced for 58V standoff voltage. It’ll start dumping a few mA around ~64V
- Capacitors are rated to 63V continuous / 72V surge
We have some people running it off of 60V nominal with no issues. Given the clamp voltage is about ~2.5V above the input voltage, I’d say (just to respect the capacitors’ nominal voltage rating) to keep it below 63V - 2.5V = 60.5V nominal input voltage, but it should be able to endure some spikes / short runtime to 64-65V no problem – heating in the TVS diode past that ~64V breakdown voltage is what I’d be most concerned about (plus premature capacitor aging, but that matters less for short spikes).
Thanks very much! That really helps me advise our client - otherwise likely to end up with very short operating life. We’ll trial with a different power architecture. (LiIon packs at around 64 - 65V when freshly charged).
Gotcha! Is this for a one-off test fixture, or for some volume production? If there’s sufficient interest, we could look at doing a customization for higher bus voltage.
Only a bit more than one off - 18 most likely for now, if the system works.
So we will probably use a high power DC-DC between the battery packs and the motor control, and the chopper will be at the output of that DC-DC. Given the recommendation, we’ll run that rail at 48-50V, so we have plenty of headroom.
Testing yesterday was promising, more next week, then order if all looks good. Hope lead time is ok from the ROW facility!