A flyback diode is a diode connected across an inductor used to eliminate flyback, which is the sudden voltage spike seen across an inductive load when its supply current is suddenly reduced or interrupted.

How does a flywheel diode work?

Freewheel diode or Flyback diodes are basically connected across inductive coils to prevent from voltage spikes in case of power getting turned off to the devices. ... When this happens then short circuit takes place through the diode. The voltage spike is thus short-circuited across the coil.

What is the purpose of a flywheel diode in motor speed control?

Purpose of Freewheeling Diode

The main purpose of freewheeling or flyback diode is to free wheel the stored energy in inductor by providing a short circuit path. This is necessary else a sudden decay in circuit current will give rise to high voltage across the switch contacts and diode.