I will explain real quick and simple way with the dyanamatic braking system
for most AC motor it is common to inject a small DC current in one of the two leads [ it will work both single and multi phase motors ] and what it do is make a magatanitc feild to slow down the rotor because of injected DC source act like counter electromagatic force to slow down the motor much quicker.
with the VSD it is easy to do this by feed little DC current to the AC motor but tricky part is to timed to how far you can inject it and when to stop injecting the DC current in the motor [ senice most VSD useally have somekind of feedback so they can able to read how far it will before it stop feeding the DC current.]
but with AC motors without VSD's this get little more trickier with this but it done often on it. they have a interlock switch on motor contractor to sense if the power is on or not when the motor is coasting it will inject the DC from power supply to slow down pretty fast but they have build in timer to stop suppling the power to the AC motor
for the DC motor it pretty straght foward it will become generator and used the load bank to slow them down pretty fast as long you are not doing the plugging it [ plugging mean reversing the connection very fast when still running ]
Hope it will help you.
If need more expain or other let me know i may find something to show ya
Wisconsin and Paris France
"Pas de problème, il marche n'est-ce pas?" (No problem, it works doesn't it?)