What is a freewheeling diode and why is it necessary in inductive loads?
1 Answer
A freewheeling diode, also known as a flyback diode, snubber diode, or commutating diode, is a diode connected in parallel with an inductive load, such as a coil or an electromagnet, in a circuit. Its primary purpose is to protect other components in the circuit from voltage spikes that occur when the current flowing through the inductive load is suddenly interrupted.
When an inductive load is energized, it stores energy in its magnetic field. When the power source is switched off or the current is reduced suddenly, the magnetic field collapses, and the energy stored in it is released. This rapid change in current can lead to a phenomenon called "inductive kickback" or "back EMF" (Electromotive Force). During this process, the voltage across the inductor can increase significantly, potentially causing voltage spikes that could damage other components in the circuit, such as transistors, switches, or even the power source itself.
The freewheeling diode provides a safe path for this induced current to flow when the inductive load is turned off. By allowing the current to circulate in a loop through the diode, it dissipates the stored energy from the collapsing magnetic field. As a result, the voltage across the inductor remains under control, preventing voltage spikes that could damage the circuit.
In essence, the freewheeling diode acts as a "flywheel" for the current, allowing it to gradually decay rather than causing sudden voltage spikes. This diode is typically connected in reverse-biased configuration across the inductive load, meaning it only conducts when the voltage across the inductor tries to rise due to the collapse of the magnetic field.
In summary, a freewheeling diode is necessary in circuits with inductive loads to prevent voltage spikes and protect sensitive components from potential damage due to the rapid changes in current flow when the inductive load is switched off.
When an inductive load is energized, it stores energy in its magnetic field. When the power source is switched off or the current is reduced suddenly, the magnetic field collapses, and the energy stored in it is released. This rapid change in current can lead to a phenomenon called "inductive kickback" or "back EMF" (Electromotive Force). During this process, the voltage across the inductor can increase significantly, potentially causing voltage spikes that could damage other components in the circuit, such as transistors, switches, or even the power source itself.
The freewheeling diode provides a safe path for this induced current to flow when the inductive load is turned off. By allowing the current to circulate in a loop through the diode, it dissipates the stored energy from the collapsing magnetic field. As a result, the voltage across the inductor remains under control, preventing voltage spikes that could damage the circuit.
In essence, the freewheeling diode acts as a "flywheel" for the current, allowing it to gradually decay rather than causing sudden voltage spikes. This diode is typically connected in reverse-biased configuration across the inductive load, meaning it only conducts when the voltage across the inductor tries to rise due to the collapse of the magnetic field.
In summary, a freewheeling diode is necessary in circuits with inductive loads to prevent voltage spikes and protect sensitive components from potential damage due to the rapid changes in current flow when the inductive load is switched off.