The basic use of ordinary thyristors is controllable rectification. Diode rectifier circuit belongs to uncontrollable rectifier circuit. If the diode is replaced by thyristor, the controllable 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 VS control pole does not input trigger pulse Ug, the VS can not be turned on. Only when the U2 is in the positive half-cycle, the thyristor is triggered when the trigger pulse Ug is applied to the control pole.
Draw its waveforms (c) and (d). Only when the trigger pulse Ug arrives, there will be voltage UL output on the load RL. If Ug arrives early, the time of thyristor turn on will be early; if Ug arrives late, the time of thyristor turn on will be late. By changing the arrival time of trigger pulse Ug on the control pole, the average UL of output voltage on the load can be adjusted. In electrical technology, the half cycle of alternating current is usually set at 180 degrees, which is called electrical angle. Thus, in each positive half week of U2, the electrical angle experienced from zero to the moment of trigger pulse arrival is called control angle a, and the conduction angle of thyristor in each positive half week is called conduction angle theta. Both alpha and theta are used to indicate the conduction or blocking range of thyristors during half a period of positive voltage. Controllable rectifier is realized by changing control angle a or conduction angle theta and changing the average UL of pulse DC voltage on load.
1: Low-power plastic-encapsulated bidirectional thyristors are usually used as acoustooptic lighting systems. Rated current: IA less than 2A.
2: large; medium power plastic and iron-sealed thyristors are usually used as power-type controllable voltage regulating circuits. Such as adjustable voltage output DC power supply and so on.
3: High-power high-frequency thyristor is usually used in industry; high-frequency smelting furnace, etc. Thyristor Purchase Welcome to www.eectech.cn
