AC input stroboflash-free LED driving circuit with high power factor

Abstract

The invention discloses an AC input stroboflash-free LED driving circuit with a high power factor, and relates to the technical field of LED driving circuits. The LED driving circuit comprises a rectifying circuit, a valley filling capacitance filtering circuit, a voltage monitoring and comparison circuit and an on-off switching control and constant current circuit, and is characterized in that an input end of the rectifying circuit is connected to the AC mains supply, an output end of the rectifying circuit is connected with an input end of the valley filling capacitance filtering circuit, the valley filling capacitance filtering circuit is connected with an input end of the on-off switching control and constant current circuit through the voltage monitoring and comparison circuit, two groups of output ends of the on-off switching control and constant current circuit are respectively connected with two groups of LED lamp strings, the on-off switching control and constant current circuit controls the two groups of LED lamp strings to be connected in series when the voltage monitoring and comparison circuit outputs low level, and the on-off switching control and constant current circuit controls the two groups of LED lamp strings to be connected in parallel when the voltage monitoring and comparison circuit outputs high level. The driving circuit has the advantages that the composition is simple, the driven LEDs operate without stroboflash, and the power factor of the system is high.

Description

technical field [0001] The invention relates to the technical field of LED driving circuits, in particular to an LED driving circuit with AC input, high power factor and no flicker. Background technique [0002] As a new type of green light source, LED light source has been more and more widely used due to its advantages of low power consumption, long life, fast response, high efficiency and energy saving. Under the same brightness, the LED light source consumes only one tenth of the power of ordinary incandescent lamps, but its life can be extended by 100 times. But its life is largely determined by the driving power supply, so a reliable, high conversion efficiency, and long-life LED driving power supply is very important for LED light sources. [0003] At present, the power supply method of LED lamps mostly adopts DC, and the mains power supply needs to be converted into DC through a rectifier bridge, and then drive the LED lamp beads to emit light through a driving circ...

AI Technical Summary

Problems solved by technology

Due to the existence of large-capacity filter capacitors, the conduction angle of the rectifier diode becomes very narrow, and it can only be turned on near the peak value of the AC input voltage, resulting in severe distortion of the AC input current and becoming a peak pulse.

This current waveform contains a large number of harmonic components, which not only pollutes the power grid, but also leads to a significant reduction in the output active power after filtering, which greatly reduces the power factor.

Although the power factor can be improved by using a switching power supply, its composition is more complicated and the cost is higher

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