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A linear constant current LED drive circuit and method compatible with thyristor dimmers

An LED driver and dimmer technology, which is applied in the direction of electric lamp circuit layout, light source, electric light source, etc., can solve the problems of LED flicker, control failure of thyristor dimmer, random occurrence, etc., to improve compatibility problems and avoid possible The effect of thyristor false turn-off phenomenon

Active Publication Date: 2018-02-13
SHANGHAI LOOALL ELECTRONICS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0015] The disadvantage of this scheme is: from the time t3, the amplitude of the rectified voltage VREC begins to be smaller than the threshold voltage of the LED unit, and the current flowing through the mains drops rapidly from I1 to I2 with a large slope, especially when the LEDs in the LED unit are two Terminal parallel capacitors (such as Figure 1a ) is especially true when smoothing the LED current waveform, which will cause the electrical circuit inside the thyristor to self-resonate. When the resonance amplitude is too large, the thyristor dimmer will be turned off by mistake. When the resonance amplitude is in a critical state At this time, the false shutdown of the thyristor dimmer will occur irregularly and randomly, resulting in the failure of the thyristor dimmer to control the load, and further, it will cause the LED connected to the thyristor dimmer to flicker

Method used

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  • A linear constant current LED drive circuit and method compatible with thyristor dimmers
  • A linear constant current LED drive circuit and method compatible with thyristor dimmers
  • A linear constant current LED drive circuit and method compatible with thyristor dimmers

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Embodiment 1

[0040] like image 3 As shown, an LED drive circuit compatible with a thyristor dimmer is powered by mains, and the thyristor dimmer is connected in series to the mains, including a rectifier bridge DB, an LED unit and a combined current source. A combined current source consists of three terminals. The positive pole of the LED unit is connected to the positive pole of the output of the rectifier bridge, the negative pole is connected to the third terminal of the combined current source, the first terminal of the combined current source is connected to the positive pole of the rectifier bridge, and the second terminal is connected to the negative pole of the rectifier bridge.

[0041] like Figure 1a As shown, the LED unit includes at least one set of LEDs, an energy storage capacitor and a diode. The energy storage capacitor is connected in parallel to both ends of the LED, the cathode of the diode is connected to the anode of the LED, the anode of the diode is used as the ...

Embodiment 2

[0063] In the second embodiment, except that the circuit structure of the dynamic current source in the combined current source is different from that of the first embodiment, other circuit structures and working principles are the same, and will not be described again.

[0064] like Figure 4 As shown, the combined current source in this embodiment also includes an LED current source, a dynamic current source, a current detection circuit and a current detection resistor, and the specific structure is as follows:

[0065] like Figure 7 As shown, the current detection circuit includes a comparator COMP1-2, a first reference signal V1-2 and a switch S1-2. The LED current source includes a second transistor Q2-2, a second operational amplifier EA2-2 and a second reference signal V2-2. The LED current source and the detection resistor Rn-2 limit the current value of the third terminal of the combined current source. . The dynamic current source includes a third transistor Q3-...

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Abstract

The invention provides an LED drive circuit compatible with a thyristor dimmer, which is powered by commercial power, and the thyristor dimmer is connected in series to the commercial power, and includes a rectifier bridge, an LED unit and a combined current source, wherein, The LED unit includes at least one set of LEDs, and the combined current source includes three terminals; the positive pole of the LED unit is connected to the output positive pole of the rectifier bridge, the negative pole is connected to the third terminal of the combined current source, and the first terminal of the combined current source is connected to the rectifier bridge The positive terminal of the rectifier bridge is connected to the negative terminal of the rectifier bridge. Its advantage is that it effectively controls the slope of the mains current drop, avoids the false shutdown of the thyristor caused by the self-resonance of the thyristor dimmer, and improves the linear LED drive scheme in the application of power supply with the thyristor dimmer. Compatibility issues in .

Description

technical field [0001] The invention relates to a power supply circuit and a method, in particular to a linear constant current LED driving circuit and a method compatible with a thyristor dimmer. Background technique [0002] In the application of LED lighting to replace incandescent lamps, it is necessary to solve the problem of compatibility with traditional thyristor dimmers in many occasions. Different from the purely resistive load of incandescent lamps, LED lighting drivers have discontinuous demand for mains current, which causes the thyristor dimmer to be turned off by mistake when the current is intermittent, resulting in brightness of LED lamps. Jumping, flickering and other incompatibility issues. [0003] The linear constant current drive scheme is expanding its market share because of its simple circuit and low cost. [0004] Current linear constant current drive schemes compatible with TRIAC dimmers, such as figure 1 As shown, the mains power is connected t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H05B37/02
Inventor 邵蕴奇
Owner SHANGHAI LOOALL ELECTRONICS CO LTD
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