Snubber Circuits in Power Electronics: Function and Types

In power electronics, a snubber circuit plays a vital role in reducing voltage spikes, switching transients, and ringing that can occur during the operation of power semiconductor devices, like diodes and transistors.

There are two main types of snubber circuits:

• Passive Snubbers: These use passive components like resistors, capacitors, and sometimes inductors.
• Active Snubbers: These incorporate active components such as transistors or operational amplifiers.

The figure below depicts passive snubber circuits (R-C and R-C-D based).

The primary purposes of a snubber circuit are detailed below:

Voltage Spike Suppression

During the switching transitions of power devices, voltage spikes or transient voltages can occur. These spikes may be caused by parasitic capacitances and inductances in the circuit. A snubber circuit absorbs and dissipates this excess energy, preventing the voltage spikes from reaching levels that could damage the semiconductor devices.

Switching Transient Damping

Semiconductor devices switch on and off rapidly in power electronic circuits, leading to abrupt changes in current and voltage. These rapid transitions can result in high-frequency ringing and oscillations. A snubber circuit helps dampen these switching transients, reducing the likelihood of overshooting, undershooting, or ringing.

Energy Dissipation

Snubber circuits provide a path for the dissipation of energy generated during switching events. This helps prevent the reflected energy from causing damage to the semiconductor devices or other components in the circuit.

Reducing Electromagnetic Interference (EMI)

Uncontrolled switching events can lead to the generation of electromagnetic interference (EMI) in the form of high-frequency noise. Snubber circuits can contribute to reducing EMI by damping switching transients and preventing unintended radiation of electromagnetic energy.

Improving Switching Performance

By controlling voltage spikes and transients, snubber circuits contribute to improving the overall switching performance of power electronic circuits. This can lead to increased reliability and efficiency.

Enhancing System Reliability

Protection against voltage spikes and transients helps enhance the reliability and lifespan of power semiconductor devices. Snubber circuits play a role in preventing premature device failure and ensuring the longevity of the power electronics system.