AC input high power factor flicker-free led drive circuit

Abstract

The invention discloses an LED drive circuit with high AC input power factor and no flicker, and relates to the technical field of LED drive circuits. The LED driving circuit includes a rectification circuit, the input end of the rectification circuit is connected to the AC mains, the output end of the rectification circuit is connected to the input end of the valley-filling capacitor filter circuit, and the valley-filling capacitor filter circuit is connected to the voltage monitoring comparison circuit. The switch switching control and the input terminal of the constant current circuit are connected, and the two output terminals of the switch switching control and the constant current circuit are respectively connected with two groups of LED light strings. When the voltage monitoring comparison circuit outputs a low level, the switch switching control and the constant current circuit Control two groups of LED light strings to be connected in series, when the voltage monitoring comparator circuit outputs a high level, the switch switching control and the constant current circuit control the two groups of LED light strings to be connected in parallel. The driving circuit has the advantages of simple composition, flicker-free operation of the driven LED and high system power factor.

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

Images