Rectifier

Many electronic circuits use DC voltage for operation. We can easily convert AC voltage or current into DC voltage or current by using a device known as a p-n junction diode. A p-n junction diode allows electric current to flow in forward bias condition and blocks the current in reverse bias condition. Simply, a diode allows electric current to flow in one direction only. This unique property of diode allows it to act as a rectifier. Let us learn more about rectifiers in this article.

What is Rectifier?

A rectifier is an electronic device that converts an alternating current into a direct current by using one or more P-N junction diodes. A diode behaves as a one-way valve that allows current to flow in a single direction. This process is known as rectification.

A rectifier can take the shape of several physical forms such as solid-state diodes, vacuum tube diodes, mercury-arc valves, silicon-controlled rectifiers, and various other silicon-based semiconductors switches.

Different Types of Rectifier

Rectifiers are mainly classified into two types as:

  1. Uncontrolled Rectifier
  2. Controlled Rectifier

Uncontrolled Rectifiers

The type of rectifier whose voltage cannot be controlled is known as an uncontrolled rectifier. Uncontrolled rectifiers are further divided as follows:

  • Half Wave Rectifier
  • Full Wave Rectifier

The type of rectifier that converts only the half cycle of the alternating current into the direct current is known as a half-wave rectifier. Likewise, a full-wave rectifier converts both positive and negative half cycles of the AC. An example of this is a bridge rectifier. A bridge rectifier uses 4 diodes that are connected in the form of a Wheatstone bridge.

Controlled Rectifiers

A type of rectifier whose voltage can be varied is known as the controlled rectifier. We use SCRs, MOSFETs and IGBTs to make an uncontrolled rectifier a controlled one. These rectifiers are preferred over their uncontrolled counterparts. There are two types of controlled rectifiers, and they are Half Wave Controlled Rectifier and Full Wave Controlled Rectifier. Half-wave controlled rectifier has the same design as the half-wave uncontrolled rectifier except we replace the diode with an SCR.

What are some applications of Rectifiers?

Some common applications of rectifiers are:

  • Rectifiers are used in electric welding to provide polarized voltage
  • Half-wave rectifiers are used as a mosquito repellent
  • Half-wave rectifiers are used as a signal peak detector in AM radio
  • Rectifiers are used in modulation, demodulation and voltage multipliers

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