Dimming control method, dimming control circuit and power converter using same

Abstract

The application discloses a dimming control method, a dimming control circuit and a power converter applying the dimming control method. The technical solution of the embodiment of the present invention adjusts the length of the switching cycle of the power converter through the dimming signal, and at the same time controls the switching state of the power switch of the power stage circuit according to the output signal of the power stage converter, or controls the switching state of the power switch according to the dimming signal On-off state avoids the problem of poor output current accuracy due to the limited response time of the internal amplifier of the circuit system and the nonlinear relationship between the current reference signal and the dimming signal when the dimming signal setting value is small, and improves the current accuracy , while achieving combined dimming to increase dimming depth and widen the dimming range.

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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