Full of useful information! How to choose a rectifier bridge?

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Full of useful information! How to choose a rectifier bridge? [Copy link]

There are many types of bridge rectifiers: flat, round, square, bench (in-line and SMD), etc., with GPP and O/J structures. The rectifier current ranges from 0.5A to 100A, and the reverse peak voltage ranges from 50V to 1600V.

A half-bridge is two diode bridge rectifiers sealed together. Two half-bridges can form a bridge rectifier circuit, and one half-bridge can also form a full-wave rectifier circuit with a center tap on the transformer.

When choosing a rectifier bridge, you need to consider the rectifier circuit and operating voltage.

Rectifier bridge stacks are generally used in full-wave rectifier circuits, which are divided into full-bridge and half-bridge.

The full bridge is composed of 4 rectifier diodes connected in the form of a bridge full-wave rectifier circuit and packaged as one.

The forward current of the full bridge has various specifications such as 0.5A, 1A, 1.5A, 2A, 2.5A, 3A, 5A, 10A, 20A, 35A, 50A, etc., and the withstand voltage (reverse voltage) has various specifications such as 25V, 50V, 100V, 200V, 300V, 400V, 500V, 600V, 800V, 1000V, etc.

The role of bridge rectifier:

1. Convert the AC power generated by the AC generator into DC power to supply power to electrical equipment and charge batteries;

2. Limit the battery current flowing back to the generator to protect the generator from being burned by reverse current.

Application of bridge rectifier:

The bridge rectifier circuit overcomes the shortcomings of the full-wave rectifier circuit, which requires the transformer secondary to have a center tap and the diode to withstand a large reverse voltage, but uses two more diodes. Today, with the rapid development of semiconductor devices and low costs, this shortcoming is not prominent, so the bridge rectifier circuit is widely used in practice.

It should be pointed out that the diode, as a rectifying element, should be selected according to different rectifying methods and load sizes. If it is not selected properly, it may not work safely or even burn the tube; or it may be overkill and cause waste.

Bridge rectifier circuit principle diagram:

The bridge rectifier circuit can also be considered as a kind of full-wave rectifier circuit. The transformer winding is connected to four diodes according to the method shown in Figure 1. D1~D4 are four identical rectifier diodes connected in the form of a bridge, so it is called a bridge rectifier circuit. The guiding effect of the diode is used to guide the secondary output to the load in the negative half cycle. The specific connection method is shown in the figure. It can be seen from the figure that in the positive half cycle, D1 and D2 guide the current from top to bottom through RL, and in the negative half cycle, D3 and D4 guide the current from top to bottom through RL, thereby realizing full-wave rectification. In this structure, if the same DC voltage is output, the secondary winding of the transformer only needs half the winding compared to the full-wave rectifier, but if the same current is to be output, the wire diameter of the winding should be thickened accordingly. As for pulsation, it is exactly the same as the full-wave rectifier circuit mentioned above.

Since the output voltage of the rectifier circuit contains a large pulsation component, in order to reduce the pulsation component as much as possible, on the other hand, the DC component must be retained as much as possible to make the output voltage close to the ideal DC, this measure is filtering. Filtering is usually achieved by using the energy storage function of capacitors or inductors.

In this experimental circuit, capacitor filtering is used, that is, a filter capacitor C is connected in parallel to the load resistor RL. The circuit is shown in Figure 2, and the waveform after filtering is as follows:

Full-wave rectifier filter waveform

Half-wave rectifier filter waveform

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