Rectifier

A large number of 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 a 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 different physical forms such as solid-state diodes, vacuum tube diodes, mercury arc valves, silicon-controlled rectifiers and various other silicon-based semiconductor switches.

Different Types of Rectifier

Rectifiers are mainly classified into two types as:

  1. Uncontrolled Rectifier
  2. Controlled Rectifier

Uncontrolled Rectifiers

The type of rectifiers 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 direct current is known as a halfwave 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’s 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 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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