What is a snubber circuit
Snubbers are circuits which are used in electrical systems to prevent the sharp rise in voltage which is a transient and it can damage or lead to failure of controlling device. Snubbers are used in semiconductor devices for protection and also to improve its performance.
Snubbers can control the effects of leakage inductance and it can improve the reliability of the power supply. snubbers can be passive or active snubber the passive snubber network element consists of resistors, capacitors, inductors, and diodes. Passive snubber can control either voltage or current
What are the functions of a snubber circuit
- It can reduce or eliminate voltage or current spikes
- Limit dI/dt or dV/dt
- Shape the load line to keep it within the safe operating area
- It transfers power dissipation from the switch to a resistor or a useful load
- It can reduce total losses due to switching
- It can reduce EMI by damping voltage and current ringing
Types of snubber circuits
There are many kinds of snubber but the most common snubbers are
- RC snubber
- RCD snubber
- Diode snubber
RC snubber
It is the most widely used snubber and it is applicable for both rate of rising control and damping a simple RC snubber consists of a small resistor in series with a small capacitor. Properly designed RC snubber can be used with either AC or DC loads, this type of snubber is used with an inductive load such as electric motors. RC snubber circuits can be used to reduce the peak power dissipation in the switch by controlling the rate of rising of drain voltage. RC snubber can absorb energy during the voltage transition and also it can reduce the efficiency
A major application of an RC snubber is to damp parasitic ringing in the circuit, the components used in the snubber must be properly selected if not it could make the snubber ineffective. Diodes which is used in the snubber must be able to handle large peak currents and the capacitors have series inductance and this must be minimized to avoid the introduction of any unwanted resonance in the circuit. The resistors used must have very low inductance to avoid excessive overshoots and ringing
RCD voltage snubber
This kind of snubber is applicable for the rate of rising voltage control and for the clamping presence of diode in the snubber will make it a polarized snubber
These are the two possible configurations for the resistor-capacitor diode snubber
RCD clamp
The purpose of the snubber in the clamp mode is to clamp the voltage during the turn off of the drain of MOSFET. When the RCD snubber is used to control the rate of voltage rise at the MOSFET drain then the capacitor must be completely charged and discharged during each cycle so that it can be able to control the rate of rising of drain voltage
Snubber diode
A snubber diode is also called as freewheeling or flyback diode, it is a diode which is used to remove the flyback, sudden voltage spike which can be seen across an inductive load when its supply voltage is suddenly reduced or removed.