vvvf Drive

Homework for school? Shame shame...

Active front end is where the shaft thingy sticks out of the motor and turns

Regenerative is when shaft thingy sticking out of the motor doesn't want to turn

Compulsory regenerative, buy a generator

Regeneration is used to recover wasted mechanical energy that would normally be dissipated with brake resistors and convert it into electrical energy. Examples are elevators going from a higher floor to a lower floor, or a crane lowering a load. The easiest and most efficient way to use this wasted energy is to connect the DC bus of multiple drives together which is easy to do for a bank of elevators.

An active front end senses that the DC bus voltage has risen over the nominal input voltage and drives AC current back to the input line (in phase with the utility). The utility power meter is effectively turning backwards when regenerating as you are delivering power to the distribution line.