Silicon Controlled Rectifier(SCR) 可控硅

可控硅(Silicon Controlled Rectifier) 简称SCR，又叫Thyristor，是一种大功率电器元件，也称晶闸管。它具有体积小、效率高、寿命长等优点。在自动控制系统中，可作为大功率驱动器件，实现用小功率控件控制大功率设备。它在交直流电机调速系统、调功系统及随动系统中得到了广泛的应用。

A Silicon Controlled Rectifier (SCR), commonly known as a Thyristor, is a high-power electrical component. It is also referred to as a thyristor. It possesses advantages such as small size, high efficiency, and long lifespan. In automatic control systems, it can be used as a high-power driving device to control high-power equipment using low-power controllers. It has found extensive applications in AC and DC motor speed control systems, power control systems, and servo systems.

可控硅分单向可控硅和双向可控硅两种。双向可控硅也叫三端双向可控硅，简称TRIAC。双向可控硅在结构上相当于两个单向可控硅反向连接，这种可控硅具有双向导通功能。其通断状态由控制极G决定。在控制极G上加正脉冲(或负脉冲)可使其正向(或反向)导通。这种装置的优点是控制电路简单，没有反向耐压问题，因此特别适合做交流无触点开关使用。

Silicon Controlled Rectifiers (SCRs) can be divided into unidirectional SCRs and bidirectional SCRs. Bidirectional SCRs are also known as TRIACs, short for 'triode for alternating current.' In terms of structure, a bidirectional SCR is equivalent to two unidirectional SCRs connected in reverse, and it has bidirectional conduction capability. Its on/off state is determined by the control gate G. Applying a positive pulse (or negative pulse) to the control gate G can make it conduct in the forward (or reverse) direction. The advantage of this device is that the control circuit is simple, there is no reverse voltage withstand problem, making it particularly suitable for use in AC contactless switches.

大家使用的是单向晶闸管，也就是人们常说的普通晶闸管，它是由四层半导体材料组成的，有三个PN结，对外有三个电极〔图2(a）〕：第一层P型半导体引出的电极叫阳极A，第三层P型半导体引出的电极叫控制极G，第四层N型半导体引出的电极叫阴极K。从晶闸管的电路符号〔图2(b）〕可以看到，它和二极管一样是一种单方向导电的器件，关键是多了一个控制极G，这就使它具有与二极管完全不同的工作特性。

Most people use unidirectional thyristors, commonly referred to as ordinary thyristors. They are composed of four layers of semiconductor materials, with three PN junctions and three external electrodes (Figure 2(a)): the electrode connected to the first layer of P-type semiconductor is called the anode A, the electrode connected to the third layer of P-type semiconductor is called the gate G, and the electrode connected to the fourth layer of N-type semiconductor is called the cathode K. From the circuit symbol of the thyristor (Figure 2(b)), it can be seen that it, like a diode, is a unidirectional conducting device, but the key difference is the presence of a control gate G, giving it completely different operating characteristics from a diode.

以硅单晶为基本材料的P1N1P2N2四层三端器件,起始于1957年，因为它的特性类似于真空闸流管，所以国际上通称为硅晶体闸流管，简称晶闸管T，又因为晶闸管最初的在静止整流方面，所以又被称之为硅可控整流元件，简称为可控硅SCR。

The four-layer three-terminal device based on single crystal silicon, designated as P1N1P2N2, originated in 1957. Due to its characteristics resembling those of a vacuum thyratron, it is internationally referred to as the silicon crystal thyratron and is commonly abbreviated as the thyristor T. Additionally, because thyristors were initially used primarily for static rectification, they are also known as silicon controlled rectifiers, abbreviated as SCRs.

在性能上，可控硅不仅具有单向导电性，而且还具有比硅整流元件（俗称"死硅")更为可贵的可控性。它只有导通和关断两种状态。

In terms of performance, the thyristor not only has unidirectional conduction capability but also a valuable controllability compared to silicon rectifying elements (commonly known as 'dead silicon'). It has only two states: conducting and non-conducting.

可控硅能以毫安级电流控制大功率的机电设备，如果超过此功率，因元件开关损耗显著增加，允许通过的平均电流相降低，此时，标称电流应降级使用。

Thyristors can control high-power electromechanical equipment with milliamp-level currents. If the power exceeds this level, the component's switching losses significantly increase, allowing for a reduction in the average current passing through it. At this point, the rated current should be downgraded for use.

可控硅的优点很多，例如：以小功率控制大功率，功率放大倍数高达几十万倍；反应极快，在微秒级内开通、关断；无触点运行，无火花、无噪音；效率高，成本低等等。

Thyristors have many advantages, such as controlling high power with low power, with power amplification factors reaching up to several hundred thousand times. They have very fast response times, switching on and off within microseconds. They operate without physical contacts, resulting in no sparks and no noise. They are highly efficient and cost-effective, among other benefits.

可控硅的弱点：静态及动态的过载能力较差；容易受干扰而误导通。

The weaknesses of thyristors include their relatively poor static and dynamic overload capabilities and susceptibility to interference, leading to inadvertent conduction.

可控硅从外形上分类主要有：螺栓形、平板形和平底形。

Thyristors can be classified based on their external appearance as bolt-shaped, flat plate-shaped, and flat bottom-shaped.

可控硅元件的结构

不管可控硅的外形如何，它们的管芯都是由P型硅和N型硅组成的四层P1N1P2N2结构。见图1。它有三个PN结（J1、J2、J3），从J1结构的P1层引出阳极A，从N2层引出阴级K，从P2层引出控制极G，所以它是一种四层三端的半导体器件。

Regardless of the external shape of thyristors, their core consists of a four-layer P1N1P2N2 structure composed of P-type silicon and N-type silicon. Refer to Figure 1. It has three PN junctions (J1, J2, J3). The anode A is connected to the P1 layer of the J1 structure, the cathode K is connected to the N2 layer, and the control gate G is connected to the P2 layer. Therefore, it is a four-layer three-terminal semiconductor device.