Thyristor zero-crossing detection circuit principle

Test - lowercase jpg

Kaixin micro test

Test probe P100-M3

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

The moment when the thyristor is put into the capacitor, that is, the moment when the thyristor is turned on, must be the same time when the power supply voltage and the residual voltage of the capacitor are the same. Because according to the characteristics of the capacitor, when the voltage applied to the capacitor changes stepwise, an inrush current will be generated, which will damage the thyristor and cause adverse effects such as high frequency oscillations in the power system. Therefore, the thyristor zero-crossing detection circuit is designed to solve the problem of residual voltage measurement. The thyristor zero-crossing detection circuit is shown in Figure 3.

When the power supply voltage is equal to the residual voltage of the capacitor, the voltage on the thyristor is zero, and the photocoupler outputs a falling edge negative pulse to the INT0 and INT1 pins of the single-chip microcomputer. If the controller inputs the command, the pulse will pass through one. In the series, the pulse train is generated to trigger the thyristor to ensure the conduction of the thyristor and the capacitor is smoothly put into the capacitor. When the voltage of the power supply and the residual voltage of the capacitor are not equal, the voltage on the thyristor is not zero, the optocoupler is turned on, and the INT0 is connected to the single chip microcomputer. INT1 is high. Setting this condition in software does not generate a trigger pulse, and the thyristor is turned off.