Snubber Circuits for Diodes

In this Article, We will be going through the Snubber Circuit, We will start our Article with the introduction of the Snubber Circuit, then we will go through its components and Construction, then we will go through its Working Principles and its Types, At last, we will go through Advantages, Disadvantages, Applications and Some FAQs.

What is a Snubber Circuit?

A snubber circuit is an electronic circuit that consists of a resistor and a capacitor connected in parallel across the switching device. A Snubber circuit is used to suppress voltage spikes that occur due to sudden interruptions or changes in current flow. It is used to protect sensitive electronic components from voltage spikes that induce high voltages. These snubber circuits are placed across semiconductor devices to protect and reduce switching losses, improving performance. Snubber circuits suppress voltage transients in electrical systems, pressure transients in fluid systems and excess force in mechanical systems.

Regardless of the type, snubber circuits require passive components such as resistors, capacitors and diode. These voltage spikes are and can lead to system failure. Snubber circuits with diodes are used to reduce these types of issues. These snubber circuits help suppress voltage transients that occur during the turn-off process of the diode. These transient spikes can cause electromagnetic interference, and voltage stress on components or can cause damage to the diode.

By using snubber circuits, we can prevent the triggering of protective circuits, reduce oscillations and improve efficiency. To understand this let us take an example, Inductive loads can generate high voltage spikes and can exceed the voltage ratings of other components. By using snubber circuits we can mitigate these spikes.

Snubber Circuit

Components and Construction of Snubber Circuits

Construction of snubber circuit is based on the desired configuration . The most common type is RC snubber circuit in which resistor and capacitor are connected in series across the device. The resistor limits the current flow and the capacitor absorbs energy from voltage spikes by suppressing the rate of voltage rise. Proper values of R and C is crucial for effective suppression of transient spikes .In RCD snubber configuration diode is connected in parallel with the resistor and capacitor .It provide low impedance path for discharge currents especially in circuits with inductive loads.

• Resistor : It is used to limit the current flow through the snubber circuit and dissipate energy .The resistance value is chosen in such way that it balances minimizing power dissipation and damping voltage transients.
• Capacitor :The capacitor is used to store and release energy and it helps to smooth out voltage spikes and suppress high frequency noise . Based on the magnitude and duration of voltage transients , capacitance value and voltage rating for the capacitor is chosen. Mainly capacitors with low equivalent series resistance is preferred to minimize the losses and improve transient response.
• Diode :Diode provides low impedance discharge path for snubber circuit when it is connected in parallel with the RC combination. Diode starts conducting when the voltage across the diode exceeds its forward voltage drop that allows transient current to bypass the protected device. Diode is chosen based on forward voltage drop and reverse recovery time.

Working Principle of Snubber Circuits

Snubber circuits for diodes works based on the principle of absorbing energy from voltage transients and limit the rate of change of voltage across the diode . In inductive loads , when a diode switch is turned off , it can create rapid changes in voltage that leads to voltage spikes and potential damage to the components and diode itself .

The most common type is RC snubber which consists of resistor and capacitor that are connected across the diode .The resistor limits the current flow through the capacitor , while the capacitor absorbs energy from the voltage spikes that prevents it from reaching high voltage levels and reduces chances of damage to the equipment .

If additional diode is added with this RC combination (i.e. RCD snubber circuit) that provides low impedance discharge path for the transient current . By controlling voltage transients , snubber circuit improves reliability , reduce electromagnetic interference and improves lifespan .

Types of Snubber Circuits

There are two configurations of snubber circuits . They are

• RC snubber circuit
• RCD snubber circuit

RC Snubber Circuit

This is the most commonly used snubber circuit which consists of a resistor and a capacitor connected across the diode . When the diode is turned off ,the inductive load tries to maintain the current flow that causes rapid change in voltage across the diode which leads to voltage spikes .It provide a path for the transient current through RC combination. The resistor limits the current flow through the capacitor that prevents excessive discharge currents .The capacitor absorbs energy from voltage spikes and suppress the voltage rise.

RC snubber circuit

RCD Snubber Circuit

The construction of RCD snubber circuit is similar to RC snubber circuit with additional diode connected in parallel .This is used for highly inductive loads .Here the diode provides the low impedance path for the discharge current and suppress the voltage spikes . It helps to absorb and dissipate the transient energy and suppress voltage spikes by allowing transient current to bypass the diode being protected.

RCD snubber circuit

Advantages of Snubber Circuits

• It effectively reduces voltage spikes that occurs during the switching process of diodes and protect them from damage.
• Snubber circuits increases reliability and reduce the risk of unexpected failures and downtime.
• Snubber circuits helps in minimizing electromagnetic interference by damping voltage spikes and reduces radio frequency interference generated by diodes during switching .
• It provides a level of protection against transient over voltages that may occur due to sudden changes in load conditions .
• By reducing voltage spikes and transient voltages , it helps in improving voltage regulation in power supply and improves efficiency .
• It helps in preventing ringing or oscillations that can occur due to voltage spikes and ensures stable operation of the system.
• Snubber circuits can effectively reduce switching noise generated during the switching process of diodes .

Disadvantages for Snubber Circuits

• Adding a snubber circuit increases the complexity of the overall circuit design as it requires additional components.
• Snubber circuits require extra components that increases the overall cost of the system.
• It may not always effectively suppress voltage spikes ,especially in high power or high frequency applications.
• Snubber circuits can introduce additional losses in the circuit , which effects the overall performance of the system .
• Selecting proper size of components may be challenging in the snubber circuits .
• In case of high frequency requiring applications ,the effectiveness of the snubber circuits may vary with the frequency of operation .

Applications for Snubber Circuits

• In motor control circuits , it helps in protecting diodes from voltage spikes caused by the inductive nature of the motor loads .
• These are used in audio amplifier circuits to suppress ringing and oscillations caused by rapid switching .
• In solar power systems , snubber circuits helps in protecting diodes in PV panels and power inverters from voltage spikes induced by change in sunlight intensity .
• Snubber circuits are used in UPS systems to protect diodes from voltage spikes and ringing during switching .
• Snubber circuits used in inverter circuits particularly in high frequency applications to mitigate voltage spikes .
• Snubber circuits are used in power converters such as buck , boost and fly back converters to suppress voltage spikes across diodes during switching .

Conclusion

Hence , snubber circuits play a vital role in enhancing performance and reliability of electronic circuits , particularly in applications where fast switching and high voltages are involved .There are two types snubber circuits ,they are RC and RCD snubbers , each offering unique advantages and suitable for different applications .

RC snubber circuits consists of a resistor and a capacitor connected in parallel across the diode. The resistor helps in dissipating energy , while the capacitor absorbs voltage spikes and reduces ringing. This type of snubber is simple in construction and effective in suppressing voltage.

Whereas RCD snubbers offer improved performance compared to RC snubbers particularly in high power and high frequency applications . Regardless of the type , snubber circuits require passive components such as resistors , capacitors and diode .The selection of these components depends on factors such as the switching frequency ,voltage levels and power ratings of the circuit. Careful consideration of these components are required to design effective snubber circuit.

Snubber Circuits for Diodes – FAQs

Are there any alternatives to snubber circuits for diodes ?

Active clamp circuits or other advanced techniques may be used as alternatives to snubber circuits for diode protection and voltage spike suppression . But these alternatives involve more complex circuit and more cost .

What types of diodes commonly use snubber circuits ?

Snubber circuits are used with fast recovery diodes ,Schottky diodes and other high speed diodes commonly found in switching power supplies , motor drives and similar applications .

When are snubber circuits are necessary for diodes ?

Snubber circuits are necessary in applications where the diode switches high voltages or currents rapidly . They are especially crucial in high frequency circuits where voltage transients and ringing can cause issues.