Dimming control method, dimming control circuit and power converter by applying dimming control method and dimming control circuit

Abstract

The invention discloses a dimming control method, a dimming control circuit and a power converter applying the dimming control method and the dimming control circuit. According to the technical schemeof the embodiment of the invention, the length of a switching period of a power converter is adjusted through a dimming signal, the on-off state of a power switch of a power circuit is controlled according to an output signal of the power converter, or the on-off state of the power switch is controlled according to the dimming signal; and the problem of poor output current precision caused by thelimited response time of an amplifier in a circuit system, the nonlinear relationship between a current reference signal and a dimming signal and the like when a dimming signal set value is small isavoided, the current precision is improved, combined dimming is achieved to improve the dimming depth, and the dimming range is widened.

Description

technical field [0001] The present invention relates to power electronics technology, in particular to LED lighting technology, and more specifically, to a dimming control circuit, a dimming control method and a power converter. Background technique [0002] In lighting applications, LED loads are widely used due to their low power consumption and fast strobe speed. In the existing LED load lighting system, the power converter controls the power stage circuit to provide output current to the LED load through pulse width modulation to light the LED load. At the same time, the power converter adjusts the brightness of the LED load according to the set value of the dimming signal (for example, the duty cycle), thereby realizing dimming. [0003] However, in this LED load lighting system, when the setting value of the dimming signal is small, that is, when the dimming depth is deep, the power converter dims the LED load, and the output current no longer changes with the dimming...

AI Technical Summary

Problems solved by technology

[0003] However, in this LED load lighting system, when the setting value of the dimming signal is small, that is, when the dimming depth is deep, the power converter dims the LED load, and the output current no longer changes with the dimming signal, usually It is called "dimming dead zone". At the same time, the power stage circuit may not be able to provide enough energy to the LED load in time, resulting in poor output current accuracy and problems such as light flickering.

Therefore, in low-dimming applications, due to the small setting value of the dimming signal, the dimming depth is deep, and the current error accumulates, thus limiting the dimming depth

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