The rectifier is an electronic device that converts alternating current into direct current. For this, it uses rectifier diodes as semiconductors. Previously vacuum valves, also called bulbs, were used for the same function.

Rectifiers are classified as single-phase, which are powered by one phase of the electric current, or three-phase, when they are powered by three. Depending on the type of rectification they perform, they can be half-wave or full-wave.

The current rectification process

The regular form of current that homes receive is alternating current. However, for household electrical appliances to work, this alternating current must first be transformed into direct current.

The rectifier is the device that transforms alternating current into direct or direct current. Without this prior rectification, equipment can suffer serious damage.

The rectifier uses diodes, which are components that allow the conduction of current in only one direction. Subsequently, the current is filtered to avoid excessively high frequencies, which can also cause damage.

History of the rectifier

The German Karl Braun patented the first rectifier, made of crystal, in 1899. Braun had previously discovered the property of semiconductor crystals to guide current in only one direction.

Later, metal rectifiers were developed, specifically copper oxide and selenium, which allowed greater power, necessary in the use of various applications.

The diodes and the rectifier

A diode is an electronic device with two terminals that allows electric current to flow through it in only one direction, blocking the passage when the current flows in the opposite direction.

Although there are several types of diodes, such as valve or bulb diodes, modern diodes, also called semiconductors, are the essential components of the most common rectifiers.

Semiconductor diodes were generally made of materials such as silicon or germanium, although there is currently a wide variety of them, made of various metals according to the specific functions for which they have been created and seeking greater effectiveness .

Types of rectifiers

There are various types of rectifiers, with specific uses for each case. The most common are the half-wave rectifier, used to eliminate the positive or negative part of the alternating current signal, and the full-wave rectifier, which converts said signal into a pulsating or pulsating output current.

There is also the so-called parallel rectifier, which is capable of fulfilling both functions and is used only in very specific cases.

The three-phase rectifier

The three-phase rectifier fulfills the same function as the single-phase rectifier, with the difference that these rectifiers are powered by three-phase sources, which makes them more efficient when handling larger powers.

Three-phase rectifiers can be controlled or not. The difference is that the controlled ones can vary the average output voltage, while in the uncontrolled one, both the input and output voltages are always fixed.

The bridge rectifier

Another type of rectifier is the so-called bridge rectifier, also known as the Graetz circuit or bridge, in honor of the German physicist Leo Graetz, who popularized it at the beginning of the 20th century, although it was invented by the Pole Karol Pollak years ago< /p>

The bridge rectifier uses four diodes, which alternate to conduct the current in specific ways, with diodes 1 and 3 carrying the positive voltage and 2 and 4 carrying the negative.


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