Importance of Freewheeling Diode in Inductive Load Circuits
In the circuit shown below, the connection of the load Resistor and inductance can be done to the Direct Current source through the switch and diode. When the switch is closed in the circuit for a few seconds, then current flows throughout the load. This current accumulates within the inductor to reach a constant value after some time.
The constant value of current is,
When the switch is opened, there is no current flow in the circuit that moves to degrade throughout the inductive load. This failure current throughout the inductor (L) results in a reverse voltage forming that is equals to L (di/dt) behind the terminals of an inductor.
Inductor circuit with freewheeling diode (In open switch)
The diode will be in forward bias due to this reverse voltage behind the terminal of the inductor. So it acts as a closed switch. Then, the main circuit can be converted to another circuit including the freewheeling diode, resistor and inductor as shown above. In this circuit, the flow of current will decrease exponentially to zero as shown below.
Inductor circuit with freewheeling diode (In closed switch)
The diode used in this circuit will consume the stored energy inside the inductor by giving a short circuit path so that high voltage cannot be created. Then the diode and switch are secured from too much voltage. The connection of this freewheeling diode can be done across an inductive load like a relay. Once the drive circuit is set free, the energy that is stored inside the magnetic field has to be left all over.
When this diode is not used or connected, too much voltage will be generated behind the inductor, so there is a possibility for damage to the driving circuit, so a freewheeling diode is used to provide a path to this energy.
Freewheeling Diode
In an Electrical circuit, a Diode is a semiconductor device that acts like a one-way switch (it allows current to flow in one direction and restricts the current to flow in another direction). Semiconductor is made up of p-type and n-type materials. Semiconductors have conductivity between conductors and insulators. To control the Load voltage, a switching element is used to switch at a particular frequency.
A severe high voltage occurs at the time the switching element is activated due to the stored energy within the magnetic field of the inductive load coming across the switching element terminals in switch OFF condition which may destroy the switching element. To distribute this energy, a Freewheeling diode is used. The Load can be short-circuited at the time the switching element is inactivated. The energy stored in the magnetic field is degenerate like heat.
Table of Content
- What is a Freewheeling Diode?
- Basics of Flyback Converters
- Operation
- Importance in Inductive Load Circuits
- Advantages
- Disadvantages
- Applications
Contact Us