Bleeding circuit and its control method and led control circuit

Abstract

The invention discloses a discharge circuit, its control method and an LED control circuit. The invention is applied to a silicon controlled rectifier dimming LED control circuit, directly or indirectly detects the zero crossing point of the input voltage, and delays the first time at the zero crossing point of the input voltage. After two hours, the discharge module works to generate the discharge current, and the time between the conduction moment of the thyristor dimmer and the moment when the input current of the drive circuit reaches a predetermined value (maintaining current of the thyristor dimmer) is the second time. for a while. During the first time, the discharge circuit produces loss. When the first time is greater than the predetermined value, the second time is extended; when the first time is less than the predetermined value, the second time is shortened so that the first time is close to or equal to the predetermined value. value. By adopting the present invention, the second time as the delay time can be adaptively adjusted according to the size of the first time and the predetermined value, thereby reducing the drain power consumption and improving the system efficiency.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a discharge circuit, a control method thereof, and an LED control circuit. Background technique [0002] LED lamps are slowly replacing existing fluorescent and incandescent lamps because they are more energy efficient and environmentally friendly than traditional fluorescent and incandescent lamps. In incandescent lamps with thyristor dimmers, LED lamps are also expected to be replaced, so LEDs need to be compatible with thyristor dimmers. However, in the application of replacing incandescent lamps with LED lamps, when the thyristor is turned on, the output terminal voltage will have a large voltage change rate (dv / dt), resulting in a large wave at the input terminal. inrush current. This surge current has a large oscillation range and a short duration, which can easily cause the thyristor to be turned off by mistake, affect the stable operation of the LED drive circ...

AI Technical Summary

Problems solved by technology

like figure 2 As shown in , it shows the waveforms of input voltage vin and input current iin. The shaded part is the current generated by the bleeder circuit. This part of the bleeder current will bring additional power consumption

And the larger the conduction angle of the thyristor dimmer, the longer the time t1 for the bleeder circuit to generate the bleeder current iblr, the greater the loss, and the lower the conversion efficiency

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