I'm using a VESC 75/300 in regen mode with a low-inductance motor to produce just over 2kW of power. The VESCs have worked well but we have seen intermittent ABS Overcurrent errors during operation and then some back-to-back ABS overcurrent errors followed by the ESCs frying. We've fried 2 ESCs so far, and we see the ABS Overcurrent errors on a couple others that have yet to fail. Any idea on what could be causing this? Could the VESC be losing sync and somehow be unable to protect itself?
For what it's worth, 2 of these 3 ICs on the front of the board seem to be physically fried as well. Not sure what the function of these ICs is.
Those IC are the gate drivers, its not uncommon for the drivers to also blow when the fets blow.
Can you give any more detail on your setup? What voltage are you running, how much regen current was the abs overcurrent faults happening at?
You say low inductance motor, how low is it? Do you have the motor config XML handy so we can have a look at your settings and/or a log file from a unit while running?
We're running a bus voltage of ~43V and we were pulling about 90 phase amps off of the motor. I haven't measured inductance recently but if my previously-measured FOC values are still correct in my motor config file, we're seeing about 0.74uH of inductance on this motor. Here's my config file: https://dpaste.org/0oFX
For what it's worth, we weren't able to get the BLDC detection to work on this motor so we hand-tweaked values until the motor worked--so our cycleintegrator and BEMF coupling may not be perfect. Any chance that either of these values being inaccurate could cause catastrophic failure like we are seeing?
I probably wouldn't try to do regen using BLDC mode with such a low inductance motor. BLDC uses a very low switching frequency at low duty cycle. So when switching its more likely that the voltage will have enough time to get high enough to cause an overvoltage condition before the VESC has enough time to react. Which would then cause the mosfet driver or mosfets to be damaged. Causing short of the fets and blowing them all up.
This is my theory, once the high side mosfets body diodes are gone then there is nothing stopping the voltage from increasing and that will cause avalanche in the low side fets, blowing them up too.
For low inductance motors you are best running in FOC at 60Khz switching frequency to reduce the voltage and current ripple as much as possible. Running 60khz should also fix your abs overcurrent faults.