What is Filter Circuit in Rectifier? – Types, Working, Advantages | New Topic [2024]

In this note, we are going to learn about a topic called “What is Filter Circuit in Rectifier?“, about its types, working principle, and advantages as well. Welcome to Poly Notes Hub, a leading destination for polytechnic notes or engineering notes as well.

Author Name: Arun Paul.

What is Filter Circuit in Rectifier?

A filter circuit in a rectifier circuit smooth the pulsing DC output produced by the rectification process. The rectifier transforms alternating current (AC) to pulsing direct current (DC), however, the pulsating DC still contains voltage fluctuations.

To eliminate these ripples and generate a smoother DC output, a filter circuit is used, which is normally made up of capacitors and, on occasion, inductors and resistors. Capacitors are very useful in this position because they can store and discharge electrical energy, filling in the gaps between the pulses of the pulsating DC and producing a more stable voltage output.

what is filter circuit in rectifier - poly notes hub

Types of Filter Circuit in Rectifier

There are various types of filter circuits that are used in rectifiers, such as –
  1. Capacitor Filter: This filter smoothes the pulsing DC waveform by connecting one or more capacitors across the rectifier’s output.
  2. Inductor Filter: In certain cases, an inductor is combined with capacitors to create a filter circuit. The inductor serves to smooth out the output by eliminating ripple.
  3. LC Filter or Pi Filter: This filter circuit uses the properties of inductors and capacitors to effectively eliminate ripple in the output.

Working of Filter Circuit in Rectifier

What is Filter Circuit in Rectifier - poly notes hub

A filter circuit operates by smoothing down a circuit’s output voltage or current, which is usually rectified from an AC to a DC signal. The primary function of a filter circuit is to reduce or eliminate ripple in the output, resulting in a more steady and continuous DC signal.

In general, a filter circuit operation as follows:
  1. Rectification: A rectifier circuit converts an alternating current input into pulsing direct current. This pulsing DC consists of a series of voltage pulses that correspond to the peaks of the AC input waveform.
  2. Filtering: The rectifier’s output is connected to a filtered circuit, which is often made up of capacitors, inductors, or a mix of the two.
    • Capacitors: Electric charge is stored in capacitors. When placed in parallel across the output, they essentially lessen the ripples’ amplitude by charging at the peaks and discharging during the troughs of the pulsing DC waveform.
    • Inductors: Current flow changes are resisted by inductors. They reduce ripple by adjusting the current variations when they are connected in series with the load.
    • Combination: Inductors and capacitors are frequently used in filter circuits together (LC filter) to improve filtering efficiency.
  3. Charging and Discharging: Capacitors store energy from the rectifier’s output during the charging phase and release it during the discharging phase to power the load continuously. Inductors contribute to a more steady output by resisting abrupt variations in current.
  4. Output: The filter circuit’s components charge and discharge, which results in a smoother, less ripple output voltage or current.

Advantages of Filter Circuit in Rectifier

Below we listed some filter circuit advantages in rectifier –
  1. These circuits reduces pulsating in the DC output.
  2. By using this circuit electronic devices run more efficiently and stable.
  3. Minimize or reduces the EMI effect.
  4. Improves reliability and performance of linked devices.
  5. Voltage regulation is used some filter circuits to keep the output voltage steady even in the face of variations.

Applications of Filter Circuit in Rectifier

Here we listed some important filter circuit application –
  1. Used in AC to DC power supply like Adapters etc.
  2. Used in rectifiers for charging batteries for small electronics devices.
  3. Used in motor control system to provide smooth supply.
  4. Used in Tele-communication system, industrial automation system, automotive systems as well.
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