Hi, I am using an ODrive Pro to control a BLDC motor. When doing tests, I get a DC_BUS_OVER_VOLTAGE error; I checked the vbus_voltage with the liveplot and it goes above the nominal voltage of my power supply (24V):
So I am connecting the ODrive Regen Clamp between the power supply and the ODrive Pro, with the 2Ohm breaking resistor (according to calculations I need 0.3Ohm < R < 6.4Ohm). Even with the Regen Clamp connected I get the same error, so I tried setting the value of the breaking resistor through the GUI, but i cannot manage to find it through the Inspector. Should I use the odrivetool instead? Otherwise how do I properly set-up the Regen Clamp with an ODrive? (In the future I plan to connect multiple ODrives to the Regen Clamp, but first I want to test the system with just one)
Hi! What’s your overvoltage trip threshold set to? The regen clamp will clamp the voltage to about 2.5V above the supply voltage, so you need some headroom in your overvoltage trip threshold – with a 24V supply, I’d probably set it to 28V or so.
Thanks a lot for your response! I had the threshold on 25.5V; indeed setting it to 28V got rid of the problem. Though I still have the doubt if I have to define/activate the brake resistor somewhere in the system, as the documentation specify that
“If you set this to a lower value than the true brake resistance then the ODrive will not meed the max_regen_current constraint during braking, that is it will sink more than max_regen_current into the power supply. Some power supplies don’t like this. If you set this to a higher value than the true brake resistance then the ODrive will unnecessarily burn more power than required during braking.”
Anyways I am using the stock resistor that comes with the Regen Clamp (2ohm, 50W), so maybe there’s no need of this (?)
Though I still have the doubt if I have to define/activate the brake resistor somewhere in the system, as the documentation specify that
Not with the regen clamp, that’s fully automatic and always enabled (and doesn’t care what the resistor value is).
Anyways I am using the stock resistor that comes with the Regen Clamp (2ohm, 50W), so maybe there’s no need of this (?)
Correct, this is only applicable for the S1 (and any future ODrives with an onboard brake resistor driver), the regen clamp will block all regenerated current assuming the brake resistor is sized correctly (which yours is – since 0.3ohm < 2ohm < 6.4ohm)
