Bleeder circuit, control method therefor, and LED control circuit

Abstract

The invention discloses a bleeder circuit, a control method therefor, and an LED control circuit. The LED control circuit which is used for the light adjustment of a silicon controlled rectifier is used for directly or indirectly detecting a zero crossing point of an input voltage. After the delay of a second time period at the zero crossing point of the input voltage, a bleeder module generates a bleeder current, and the period between the conduction moment of a silicon controlled rectifier light modulator and a moment when the input current of a drive circuit reaches a preset value (a maintaining current of the silicon controlled rectifier light modulator) is a first time period. In the first time period, the bleeder circuit generates loss. When the first time period is greater than a preset value, the second time period is prolonged; when the first time period is less than the preset value, the second time period is shortened, and the first time period is enabled to approach to or to be equal to the preset value. According to the invention, the second time period serving as the delay time can be adaptively adjusted according to the size of the first time period and the size of the preset value, and the bleeder power consumption is reduced. Moreover, the system efficiency is improved.

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] Because LED lamps are more energy-saving and environmentally friendly than traditional fluorescent lamps and incandescent lamps, LED lamps are slowly replacing existing fluorescent lamps and incandescent lamps. In incandescent lamps with thyristor dimmers, it is also desirable to use LED lamps to replace them, so LEDs must be compatible with thyristor dimmers. However, in the application of LED lamps to replace incandescent lamps, due to the large voltage change rate (dv / dt) at the output terminal voltage when the thyristor is turned on, it will cause a large wave at the input terminal. inrush current. This surge current has a large oscillation amplitude and short duration, which can easily cause the thyristor to be turned off by mistake, affect the stable operatio...

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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