How does regenerative braking work in motor drives?

Regenerative braking captures kinetic energy during deceleration and returns it to the source. When motor is driven above synchronous speed by load inertia, it becomes a generator. The inverter operates in regenerative mode, converting mechanical energy to electrical. DC link voltage rises; this energy can charge batteries (EVs), feed back to grid (with active front-end rectifier), or be dissipated in braking resistors (dynamic braking). Regeneration improves efficiency by 10-30% in frequent start-stop applications like elevators and trains.