I mentioned my experience in a different thread, but wanted to repeat it here, since this felt like a serious event.
https://vesc-project.com/comment/5942#comment-5942
While logging data I was coasting downhill with a little more speed (perhaps 10 %) than the drive can normally produce, and started regen braking a bit (using FOC). The actual brake was a lot stronger than requested! Link to graph (28k eRPM = 25 km/h):
https://drive.google.com/file/d/1D5ubzv8y31OpDeS496Ngf6iAxujVAgwt/view?usp=sharing
Fortunately there was no damage. My settings have max regen current of -11.6 A and max brake current of -33A. The graph shows actual regen current of -37 A, and phase current of -52 A. Hardware is original VESC 6 MKIV. The control "app" is a customization of app_adc.c that uses a second throttle for braking and reverse w/o button (thanks district9prawn). There is also an automatic throttle holding feature, but that's inactive during coast. Link to code (ctrl_type = ADC_CTRL_TYPE_CURRENT_REV_BUTTON_BRAKE_ADC):
https://drive.google.com/file/d/16Jz7Y-fYGoNJ8C6Kp0cVK26Pa_YigunB/view?usp=sharing
I vaguely remember reading that high speed coasting presents a problem for the controller, because the battery voltage can't match the EMF. But even if proper FOC is unavailable, there must be ways (dangerous words, I know) to get controlled braking current. Incurring some torque ripple seems preferable to slamming the brake.
To work around this and since I have a mechanical brake, my app_adc.c will probably just check duty cycle before applying the e-brake.