[sbradford26]

This can only be done with permanent magnetic motors which is not the norm for EVs for many reasons. In a non permanent magnetic motor on loss of power there is no energy to dump into braking resistors since the motor is not causing any resistance because the coils have been de-energized.

[extrapickles]

Most EVs have permanent magnet motors of some flavor right now (some have both a PM motor and a pure induction). I would assume that if you were having the motor be the primary braking system, and it was induction, there would be a tiny cheap magnet installed in it to generate bootstrap power to prevent exactly this scenario.

[londons_explore]

An even simpler design is to assume that the car can only start moving when there is power. If there is a loss of power while moving, then you can use the energy in the HV capacitors in the inverters to make a bootstrap field. That can be maintained till the car stops (and the user still has control of when/how much to brake). When the car comes to a halt, the parking brake is applied, and it won't move again till repaired.

All of that can be done with software-only - no hardware changes needed.