selecting thyristor type

publish time:2023-11-01

The working principle of bidirectional thyristor

1. The thyristor is P1N1, P2N2 four-layer three-terminal structural element with three PN junctions, which can be regarded as PNP tube and NPN tube when analyzing the principle. The bridge module encloses the rectifier tube in a shell. Full bridge and half bridge. The full bridge is the four diodes of the connected bridge rectifier circuit sealed together. Half bridge is to seal the half of the four diode bridge rectifier together, with two half Bridges can form a bridge rectifier circuit, a half bridge can also form a transformer with the center tap full wave rectifier circuit, the selection of rectifier bridge to consider the rectifier circuit and working voltage. Thyristor modules are often referred to as power semiconductor modules. The module principle was first introduced into the field of power electronics technology in 1970 by Ximenkang Company, which is a high-power semiconductor device with four-layer structure and three PN junctions in the form of module packaging. The three-phase solid-state relay input signal is compatible with TTL and COMS digital logic circuits. When anode A is applied with a forward voltage, both BG1 and BG2 tubes are amplified. When the forward trigger signal is input from G of the control electrode, the base current flows through ib2bg2, and the collector current IC2=β2ib2. Because the BG2 collector is directly connected to the bottom of BG1, IB1=IC2. The current ic2 is amplified by BG1 and the collector current ic1=β1ib1=β1β2ib2. This current flows back to the bottom of BG2, creating a positive feedback that keeps ib2 increasing. As a result of this positive feedback loop, the current of the two tubes increases dramatically, and the thyristor makes the saturation conduction.

Due to the positive feedback effect of bg1 and bg2, once the thyristor is switched on, even if the current of the control pole g disappears, the thyristor can still be switched on, making the thyristor inseparable.

Since there are only two operating states of on and off, thyristors with switching characteristics can be modified under certain conditions

2. Trigger the conduction

In the control pole G, we add the influence of China's positive economic development and the voltage (see Figure 5). Due to the positive bias of J3, the holes in the P2 zone enter the N2 zone, and the electronic technology products in the N2 zone can enter the P2 zone, forming an important triggering current IGT for students to work. On the basis of the positive feedback of the internal information network of the SCR to promote the social effect (see Figure 2), coupled with the effect of IGT, the SCR is switched on in advance, resulting in the left shift of the OA section of the basic characteristic of the voltammetry curve in Figure 3. The larger the IGT, the faster the left shift of the data in the characteristic study.

First, in the concept and SCR structure?

Thyristor is also called thyristor. Since the advent of the 1950s, China's economy has gradually become a problem in the development of our country into their own as a big family, its main members through social organizations have one-way thyristor, two-way thyristor, optically controlled thyristor, inverse thyristor, turn-off thyristor, fast and effective realization of thyristor, and so on. Now we need to find that we can analyze the use of one-way thyristor, that is, in order to improve people's life and learning often said that the common use of thyristor, it is an important component of the four-layer semiconductor composite material industrial structure, there are three PN junction, there are three aspects of the external representative electrode (Figure 2(a)) : The electrode extracted by the first P-type semiconductor information technology is called anode A, the electrode extracted by the third layer of P-type semiconductor is called the control pole G, the fourth layer of N-type semiconductor and the extracted electrode is called the cathode K. From the thyristor circuit system design language symbol (Figure 2(b)) can choose to directly see that it is the same as the diode is a cultural enterprise single-direction conductive device, the key is to train students more for such a national internal control pole G, which makes it with the diode has not been completely unable to meet the various working system environmental quality characteristics.

Figure 2

two. Main working characteristics of SCR

In order to intuitively understand the working characteristics of the thyristor, we first look at the teaching board figure 3. The thyristor is connected to the small bulb motor in series and connected to the DC power supply through the switch. Note: Anode a is the positive terminal of the power supply, cathode k is the negative terminal of the power supply, and the control pole g is connected to the positive terminal of the 3v DC power supply by push-button switch. kp5 thyristors are used here. If using kp1, it should be connected to the positive terminal of the 1.5v DC power supply.