Principle of rectifier diode

Principle of rectifier diode

A device that converts alternating current into direct current electrical energy. Usually it contains a PN junction with two positive and negative electrodes. The most important characteristic of a diode is its unidirectional conductivity. In the circuit, current can only flow in from the anode of the diode and flow out from the cathode.

In two types of rectifiers based on high-power diodes or thyristors, the high-voltage AC power of the grid is transformed into DC power through a transformer.

Obviously, this latest type of rectifier technology contains more content to be developed, but it can show advantages, for example, it is loaded on the power grid with very small harmonic interference and a power factor of 1.

As a typical case, the on-load tap changer controls the input AC voltage on the primary side of the rectifier transformer, and can also control the output DC value within a certain range.

Usually the on-load tap changer is used in combination with a saturable reactor connected in series in the output circuit of the rectifier. By introducing direct current into the reactor, a variable impedance is generated in the line.

Therefore, by controlling the voltage drop across the reactor, the output value can be controlled within a relatively narrow range.

Thyristor rectifiers are very close to diode rectifiers in design. Because the electrical parameters of the thyristor rectifier are controllable, there is no need for an on-load tap changer and a saturated reactor.

Because the thyristor rectifier contains no moving parts, maintenance of the thyristor rectifier system is reduced.

Note that the adjustment speed of the thyristor rectifier is faster than that of the diode rectifier. During the process characteristic step, the thyristor rectifier is often adjusted so quickly that overcurrent can be avoided.

As a result, the overload capacity of the thyristor system can be designed to be smaller than that of the diode system.

The function of the rectifier is to convert alternating current into direct current. In addition to supplying electricity for DC appliances, it is also necessary to charge the battery.

Rectifiers have a wide range of uses. Rectifiers are used in all kinds of vehicles, such as chargers, TVs, radio recorders, DVDs, and VCDs.