Thyristor, short for thyristor rectifier element, is a high-power semiconductor device with a four-layer structure of three PN junctions, also known as thyristor. It has the characteristics of small size, relatively simple structure and strong function, and is one of the most commonly used semiconductor devices. The device is widely used in various electronic equipment and electronic products, mostly used for controlled rectification, inverter, frequency conversion, voltage regulation, contactless switch and so on. Thyristor devices are widely used in household appliances such as dimming lights, speed regulating fans, air conditioners, TV sets, refrigerators, washing machines, cameras, combined audio, acousto-optic circuits, timing controllers, toy devices, radio remote control, cameras and industrial controls.

use

The most basic use of ordinary thyristors is controlled rectifier. The familiar diode rectifier circuit belongs to uncontrollable rectifier circuit. If the diode is replaced by a thyristor, a controlled rectifier circuit can be formed. Taking the simplest single-phase half-wave controllable rectifier circuit as an example, during the positive half cycle of sinusoidal AC voltage U2, if the control pole of VS does not input trigger pulse Ug, VS still cannot be switched on, only when U2 is in the positive half cycle and the control pole is applied trigger pulse Ug, the thyrisor is triggered to switch on. Draw its waveforms (c) and (d), only when the trigger pulse Ug arrives, there is a voltage UL output on the load RL. If Ug comes early, the time of thyristor conduction is early. Ug comes late, the thyristor conduction time is late. The average UL of the output voltage on the load can be adjusted by changing the time when the trigger pulse Ug on the control pole arrives. In electrical technology, the half cycle of alternating current is often set at 180°, which is called the electrical Angle. Thus, in each positive half cycle of U2, the electrical Angle experienced from the zero value to the moment the trigger pulse arrives is called the control Angle α; The electrical Angle of thyristor conduction in each positive half cycle is called the conduction Angle θ. Obviously, both α and θ are used to indicate the on-off or off-range of the thyristor during half a cycle of positive voltage. By changing the control Angle α or the conduction Angle θ, the average UL of the pulse DC voltage on the load is changed, and the controlled rectification is realized.

1: Low power plastic sealed bidirectional thyristor is usually used in a silent light control lighting system. Rated current :IA less than 2A.

2: large; Medium power plastic-sealed and iron-sealed thyristors are commonly used as power type controllable voltage regulator circuits. Like adjustable voltage output DC power supply and so on.

3: High-power high-frequency thyristor is usually used in industry; High frequency melting furnace, etc.