Hello,
As you are aware, VESC currently uses a linear thermal rollback mechanism. As temperature increases motor current is decreased. This works for safety but leaves performance on the table.
Currently, a user bottlenecked by motor thermals is incentivized to set their limits as high as possible for the most thermal headroom, however as temperature rises resistive losses increase and eventually outpace the increased cooling from higher temperature difference.
Instead of treating thermal rollback as a safety feature it could be a part of the system. A PID temperature rollback feature could provide:
- Optimal Equilibrium Tracking where a user could define a target temperature and VESC would calculate the exact maximum wattage the motor can sustain to stay at that temperature maximizing continuous power.
- Predictive protection as the current system is purely reactive a rapid temperature spike might lead to full temperature cutoff as the temperature sensor lags behind the actual core temperature, a PID systems Derivative Term could predict the spike based on the rate of change of temperature and reduce the current in time to not lead to full temperature cutoff.
- Automatic tuning since VESC already detects many electrical parameters a thermal detection routine could measure the motors thermal resistance allowing the PID to be pre-tuned to the motors specific ability to shed heat.
This would effectively provide a software boost to the continuous power of the motor.
It's worth noting I am not a motor control expert, these are just some thoughts I had.
I'd love to hear your thoughts on whether this is something the VESC project would consider implementing.
Best,
Selone