Dimming circuit and control method compatible with thyristor dimmer

Abstract

The invention discloses a dimming circuit compatible with a silicon controlled rectifier dimmer and a control method. The dimming circuit includes an input voltage source, a rectification circuit, the silicon controlled rectifier dimmer, a dimming circuit and an output circuit, wherein the input voltage source is connected with the rectification circuit and the silicon controlled rectifier dimmer respectively, the rectification circuit is connected with the dimming circuit, the dimming circuit is connected with the output circuit, and the output circuit includes an isolation transformer, a switch tube, a third sampling resistor, a flyback diode, a filtering capacitor and an output LED load. The dimming circuit compatible with the silicon controlled rectifier dimmer is characterized in that the dimming circuit includes a sampling circuit used for sampling the phase-cut angle of the silicon controlled rectifier dimmer, a control and logic circuit which is controlled by the phase-cut angle, and a phase-cut angle setting circuit which can control the switching on and switching off of the switch tube according to the status of an inputted phase-cut angle. With the dimming circuit compatible with the silicon controlled rectifier dimmer of the invention adopted, the problem of flicker appearing in a traditional dimming process can be effectively solved, and at the same time, a dimming purpose can be achieved.

Description

Technical field [0001] The patent of the invention relates to a dimming circuit and a control method compatible with a thyristor dimmer, in particular to a dimming circuit and a control method for LED lamps by using a traditional incandescent lamp thyristor dimmer. Background technique [0002] Nowadays, due to the rapid development of LED lighting, the original incandescent lamps of tens of watts can be directly replaced with LED bulbs of several watts, which can save a lot of energy. Many dimming methods of incandescent lamps use thyristor dimmers for phase-cut dimming. Because the traditional incandescent lamp is a purely resistive load, it can be directly phase-cut dimmed with a thyristor dimmer. Since traditional incandescent lamps are mostly tens to hundreds of watts, the design of thyristor dimmers is designed with this as a load. However, if this kind of thyristor dimmer is used to dim an LED lamp of several watts, since the LED lamp is not a pure group load, it will ca...

AI Technical Summary

Problems solved by technology

In addition, due to the large leakage current of the thyristor dimmer when it is turned off, it will affect the working status of the thyristor and the LED power supply, thereby causing flickering and other phenomena.

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