What is a flywheel diode? How does it prevent voltage spikes?
1 Answer
A flywheel diode, also known as a freewheeling diode or a snubber diode, is an electronic component used to suppress voltage spikes or transients that occur when an inductive load, such as a motor or a relay coil, is turned off. When current flows through an inductive load, it creates a magnetic field around the load. When the current is suddenly interrupted, this magnetic field collapses, causing a rapid change in the magnetic flux. This change in flux induces a voltage across the inductor in an attempt to maintain the current flow, resulting in a voltage spike that can potentially damage other components in the circuit.
A flywheel diode is connected in parallel with the inductive load, but in the opposite direction to the flow of current. When the inductive load is switched off, the diode provides a low-resistance path for the circulating current, allowing the energy stored in the magnetic field to dissipate gradually. This prevents the sudden collapse of the magnetic field and the associated voltage spike.
Here's how a flywheel diode prevents voltage spikes:
Normal operation: When the inductive load is active, current flows through both the load and the diode. The diode is reverse-biased, meaning it doesn't conduct current in this direction.
Turn-off phase: When the inductive load is turned off, the current would normally want to continue flowing through the inductor. However, since the diode is connected in the opposite direction, it becomes forward-biased, allowing the circulating current to flow through it.
Energy dissipation: The flywheel diode provides a path for the circulating current to flow, allowing the energy stored in the inductor's magnetic field to dissipate gradually as heat. This prevents the sudden collapse of the magnetic field and the resulting voltage spike.
By providing a controlled path for the current to flow after the switch-off, the flywheel diode effectively dampens the voltage spikes that could otherwise damage sensitive components in the circuit.
It's important to select a flywheel diode with appropriate specifications for the given application, taking into account factors such as the maximum current and voltage ratings, as well as the switching speed of the circuit.
A flywheel diode is connected in parallel with the inductive load, but in the opposite direction to the flow of current. When the inductive load is switched off, the diode provides a low-resistance path for the circulating current, allowing the energy stored in the magnetic field to dissipate gradually. This prevents the sudden collapse of the magnetic field and the associated voltage spike.
Here's how a flywheel diode prevents voltage spikes:
Normal operation: When the inductive load is active, current flows through both the load and the diode. The diode is reverse-biased, meaning it doesn't conduct current in this direction.
Turn-off phase: When the inductive load is turned off, the current would normally want to continue flowing through the inductor. However, since the diode is connected in the opposite direction, it becomes forward-biased, allowing the circulating current to flow through it.
Energy dissipation: The flywheel diode provides a path for the circulating current to flow, allowing the energy stored in the inductor's magnetic field to dissipate gradually as heat. This prevents the sudden collapse of the magnetic field and the resulting voltage spike.
By providing a controlled path for the current to flow after the switch-off, the flywheel diode effectively dampens the voltage spikes that could otherwise damage sensitive components in the circuit.
It's important to select a flywheel diode with appropriate specifications for the given application, taking into account factors such as the maximum current and voltage ratings, as well as the switching speed of the circuit.