dynamic braking in squirrel cage induction motor

I think the way this works is that a braking VFD dissipates the energy back into the incoming power supply. If other loads in the plant do not use this energy, it goes back to the grid. This is better than wasting it as heat. If you have VFDs in your facility, the supplier may be able to give you further information on this.

In order for a motor to become a generator, the mechanical speed must exceed the synchronous speed.You cannot have dynamic braking without something like a VVVF drive! The drive monitors the motor speed and back emf, using that to apply a lowering frequency so that the effective synchronous speed is always lower than the mechanical speed. That keeps the motor always in regeneration, pumping energy back nto the DC bus of the drive. But without the resistors to take that energy out, it would exceed the bus rating of the drive and destroy it. So the drive has a DC-DC "chopper" circuit that fires into the resistor bank whenever the DC bus level exceeds the setpoint.

The next level up is called a Line Regenerative VFD, which is essentially two VFDs back-to-back. As the DC bus is charged during braking, the front-end section re-fires the energy back into the line so that it can be used elsewhere.

Thank you for your valuable tips.

So, how does a squirrel cage rotor generate a back emf? Please humor me.