In power electronics, a snubber circuit serves the purpose of reducing or eliminating voltage spikes and transient voltage overshoots that can occur in certain switching devices, such as power diodes and power transistors, during their switching operations. These voltage spikes and transients can lead to several issues, including increased electromagnetic interference (EMI), stress on the switching devices, and potentially damage to the components.
The primary function of a snubber circuit is to dampen these voltage spikes and transients by providing a controlled discharge path for the excess energy stored in the parasitic capacitance and inductance of the circuit. The snubber accomplishes this by using passive components such as resistors, capacitors, and sometimes diodes.
There are two common types of snubber circuits used in power electronics:
RC Snubber: This type of snubber circuit consists of a resistor (R) and a capacitor (C) connected in parallel with the switching device. During switching, when there is a sudden voltage change across the device, the capacitor quickly absorbs the excess energy, preventing it from causing a voltage spike. The resistor then gradually dissipates this stored energy, ensuring a controlled discharge and reducing voltage overshoot.
RCD Snubber: This type of snubber circuit includes an additional diode (D) in series with the RC snubber. The diode helps to provide a discharge path for the stored energy when the switching device is in the off state, further enhancing the snubbing effect.
By using snubber circuits, power electronics designers can improve the overall reliability and efficiency of their circuits, reduce EMI emissions, and protect the switching devices from potential damage caused by voltage spikes and transients. However, it's essential to design snubber circuits carefully, considering the specific application and characteristics of the switching devices to achieve the desired damping effect without introducing other unwanted complications.