Full-wave rectifier and its operation principle

A rectifier is a converter of electrical energy, which is a semiconductor or electrovacuum device that converts an alternating input current into a constant output. The full-wave rectifier is built on a half-bridge or bridge circuit, the detailed formation of which we will consider.

Essence and arrangement of full-wave rectifiers

Most of these devices create a unidirectional pulsating voltage. To smooth out the ripple, use special filters.
To improve the parameters of the rectifier, it is necessary to ensure the current flows to both half-periods of the input voltage. For this purpose, two types of half-wave rectification circuits are used , which work both in phase and synchronously with a single load.

With this switching on you will need two primary voltage sources that will have a common point. This scheme is called a "full-wave rectifier with an average point". In this case, the average value of the voltage in the load resistors during the full-wave rectification will exceed twice the similar parameters of the half-wave circuit.

It should be noted that the two-half-cycle scheme, which has an average point, has its negative aspects. When the current passes one diode, on the opposite side, the reverse voltage in the peak phase reaches its doubled input maximum voltage, which should be remembered when choosing diodes for the rectifier.

In this regard, we will examine in more detail the full-wave rectifier, which possesses a metal-intensive circuit having a large active equivalent internal resistance. This causes the presence of large losses associated with significant heating of the transformer winding.

When constructing such a circuit with a smoothing capacitor, it is necessary to take into account that the measurement of the alternating voltage is always carried out at effective values, which are much smaller than the maximum amplitude. If there is no load on the capacitor, the rectified voltage is always equal to the amplitude voltage. This means that a full-wave rectifier having a single-phase alternating current of 12 V on the capacitor will receive a voltage equal to 17 V. In the absence of a load, a voltage of 17 V can be obtained. Based on this, it can be concluded that under load, the rectified voltage decreases, but does not become less than the existing voltage of the variables Currents and will be determined by the capacitance of the smoothing capacitor.

The circuit of such a rectifier can be described as follows. In order to suppress noise, the primary winding of the transformer is connected to a filter, which consists of two capacitors with an attached midpoint to the ground. They are necessarily unipolar, and in order to reduce the probability of breakdown, their nominal voltage is 200 V.

Typically, the switch is installed in front of the capacitor, which is necessary to prevent the supply of mains voltage when the rectifier is operating on the capacitors. The full-wave rectifier has a secondary winding of the transformer with a central terminal, but there is no need for a bridge circuit in this terminal. The filter for the rectifier is two capacitors and a series resistor. However, with a low level of ripple, it is permissible to add one more capacitor and a resistor to the output.

Since electric machines operate in accordance with the principle of reversibility, voltage rectifiers Together with the inverter are two types of electric machine. An inverter is a device that converts a constant voltage into an alternating voltage.