I’m working on my first Odrive setup, with an Odrive Pro, magnetic encoder AS5047 and a T-Motor R100 90kv BLDC motor. We expect to run the system at 12S (50v) but for the moment we are only using a 6S LiPo battery.
We are having an issue in velocity control, when we reach a certain rpm, the DC_BUS_OVER_VOLTAGE error pops up. Our ‘config.dc_bus_overvoltage_trip_level’ is set to 4.25*6 = 25.5v and it does seem that when we reach a certain rpm, there are voltage spikes that might be triggering this error:
In this test we simply increase steadily the velocity to around 12 turns/s (with no load other than the friction of the system), where the spikes appear and the error is triggered.
Is this because we don’t have a break resistor or a regen clamp module in the Odrive Pro’s case? Just in case, we tried to increase the max negative current from 1C to 1.5C to see if it made any difference, but the result was the same.
Thank you in advance!
Apologies, it seems that the issue was external to the Odrive: we have a couple of mosfets between the battery and the odrive as a safety measure and that seemed to be causing the spikes. A direct connection from the Lipo to the Odrive seems to solve the issue.
Yes - definitely if you have some blocking / safety FETs that are raising the bus impedance, it could cause issues (or if they’re turned off and just conducting through the body diodes).
Glad to hear you figured the issue out let me know if there’s anything I can help with!
Thanks for the answer! It does seem that we have a safety diode that is causing the blocking.
In that case we might need to use a regen clamp module for now, since we might not be able to change the configuration of the external electronics or we might not even use a battery in the end, but a power generator. For that we see that the recommended clamp module goes from 50W to 800W peak. We expect to be working at 50V and 40A continuous with peaks of maybe100A (hard to quantify for now). We don’t need to accelerate and decelerate really fast, but maybe the recommended clamp is not suitable for our power requirements? If that’s true, could you recommend a suitable one for us?
We’ll actually have a first party regen clamp available for engineering samples in the near-ish future will be able to hit those numbers and more! Happy to let you know when they’re available!
Sure let us know! We are in need of a waay shorter term solution though, so if there’s a readily available clamp capable of our required numbers, it’d be amazing hehe
I think we’ll manage in the meantime, thanks!