3BHL000390P0104 ABB 5SHX1960L0004 简述晶闸管的工作原理

3BHL000390P0104 ABB 5SHX1960L0004晶闸管又叫可控硅。晶闸管是可以处理耐高压、大电流的大功率器件，随着设计技术和制造技术的进步，越来越大容量化。到现在为止，，已经衍生出了单向晶闸管、双向晶闸管、光控晶闸管、逆导晶闸管、可关断晶闸管、快速晶闸管，等等主要几个类型。

3BHL000390P0104 ABB 5SHX1960L0004晶闸管分为螺栓形和平板形两种，螺栓形这种结构更换元件很方便，用于100A以下的元件。平板形，这种结构散热效果比较好，用于200A以上的元件。晶闸管是由四层半导体构成的。图右所示为螺栓形晶闸管的内部结构，它由单晶硅薄片P1、N1、P2、N2四层半导体材料叠成，形成三个PN结。图 (b)和(c)所示分别为其示意图和表示符号。

3BHL000390P0104 ABB 5SHX1960L0004晶闸管为半控型电力电子器件，它的工作条件如下：

1. 晶闸管承受反向阳极电压时，不管门极承受何种电压，晶闸管都处于反向阻断状态。

2. 晶闸管承受正向阳极电压时，仅在门极承受正向电压的情况下晶闸管才导通。这时晶闸管处于正向导通状态，这就是晶闸管的闸流特性，即可控特性。

3. 晶闸管在导通情况下，只要有一定的正向阳极电压，不论门极电压如何，晶闸管保持导通，即晶闸管导通后，门极失去作用。门极只起触发作用。

4. 晶闸管在导通情况下，当主回路电压（或电流）减小到接近于零时，晶闸管关断。

3BHL000390P0104 ABB 5SHX1960L0004晶闸管的工作原理：

　　晶闸管在工作过程中，它的阳极（A）和阴极（K）与电源和负载连接，组成晶闸管的主电路，晶闸管的门极G和阴极K与控制晶闸管的装置连接，组成晶闸管的控制电路。

　　（1）单向晶闸管工作原理

　　单向晶闸管是PNPN闪层结构，形成三个PN结，具有阳极人、阴极K和控制极G三个外电极。单向品闸管可等效为PNP， NPN两个晶体管组成的复合管，如图4-46所示。

5SHX1960L0004 3BHL000390P0104

3BHL000390P0104 ABB 5SHX1960L0004 thyristor is also called thyristor. Thyristors are high-power devices that can handle high voltage and high current. With the development of design technology and manufacturing technology, more and more capacity becomes available. So far, there have been several main types of unidirectional thyristors, bidirectional thyristors, optically controlled thyristors, reverse-guided thyristors, turn-off thyristors, fast thyristors, and so on.

3BHL000390P0104 ABB 5SHX1960L0004 thyristors are divided into two types: bolt-shaped and flat-shaped. Bolt-shaped thyristors are convenient to replace components and are used for components below 100A. Flat plate shape, this structure has a better heat dissipation effect, and is used for components above 200A. The thyristor is made up of four layers of semiconductors. The internal structure of a bolt-shaped thyristor is shown on the right. It consists of four layers of semiconductor material, P1, N1, P2 and N2, and forms three PN junctions. Diagrams and symbols are shown in figures (b) and (c) respectively.

3BHL000390P0104 ABB 5SHX1960L0004 Thyristor is a semi-controlled power electronic device, and its operating conditions are as follows:

1. When the thyristor is subjected to reverse anode voltage, no matter what voltage the gate is subjected to, the thyristor is in a reverse blocking state.

2. When the thyristor is subjected to positive anode voltage, the thyristor is only switched on when the gate is subjected to positive voltage. At this time, the thyristor is in a positive pilot state, which is the thyristor characteristics, that is, controllable characteristics.

3. When the thyristor is on, as long as there is a certain positive anode voltage, regardless of the gate voltage, the thyristor remains on, that is, after the thyristor is on, the gate loses its function. The gate only acts as a trigger.

4. When the thyristor is on, the thyristor is turned off when the main loop voltage (or current) is reduced to near zero.

3BHL000390P0104 ABB 5SHX1960L0004 Thyristor working principle:

In the working process of the thyristor, its anode (A) and cathode (K) are connected with the power supply and load to form the main circuit of the thyristor, and the gate G and cathode K of the thyristor are connected with the device controlling the thyristor to form the control circuit of the thyristor.

(1) Working principle of unidirectional thyristor

The unidirectional thyristor is a PNPN flash layer structure, which forms three PN junctions and has three external electrodes: anode man, cathode K and control pole G. A one-way commodity gate can be equivalent to a compound pipe consisting of two PNP and NPN transistors, as shown in Figure 4-46.