Strobe-free alternating current drive LED light source dimming system and method thereof

Abstract

The invention provides a strobe-free alternating current drive LED light source dimming system and a method thereof. The system comprises a rectifying module, an LED array, a switch module, a sampling module, a drive power supply chip and a voltage-controlled current source module. The rectifying module is used for rectifying received alternating current and outputting work voltage. The LED array comprises multi-stage lamp groups divided according to progressive increasing number of serially-connected LEDs. The switch module comprises a plurality of switches correspondingly connected to an output end of each stage of lamp groups, and the switches are used for communicating and cutting off a power supply circuit of each stage of lamp groups. The sampling module comprises multi-stage sampling resistor strings according to progressive decreasing number of serially-connected resistors. The drive power supply chip is used for providing a standard level for the power supply circuit of each stage of lamp groups. The voltage-controlled current source module is used for generating a direct current level in a preset range according a lighting control signal output by a light control center, and the direct current lever generates bias current to modulate amplitude and dim an LED light source. LED current can be changed by changing external bias current according to the control signal, and strobe-free deep dimming can be achieved.

Description

technical field [0001] The invention relates to an LED light source dimming system and method, in particular to a flicker-free AC-driven LED light source dimming system and method. Background technique [0002] At present, the main obstacle for LED lighting technology to be widely accepted by the market is the price of LED lighting systems. According to the results of cost comparison and service life analysis, compared with LED lighting systems driven by switching power supplies, AC-driven LED lighting systems have obvious advantages in terms of price and life. It is a very powerful measure to increase the price of lighting products and promote the application of LED lighting. [0003] In LED lighting control, how the drive power supply recognizes the received control signal, how the power supply responds to the control signal and realizes the change of output power (dimming) is closely related to the topology of the LED power supply, so the dimming control technology of AC...

AI Technical Summary

Problems solved by technology

The resulting risk is: the control signal sent from the outside adjusts the reference level of the chip to a very low level, which will cause the power chip to work unstable due to the low signal-to-noise ratio, resulting in LED strobe

[0007] Therefore, there is a need for an effective and low-cost method to avoid the stroboscopic and EMI problems caused by the phase-cut dimming method, as well as the problems caused by the chip reference level being too low when deep AM dimming is used in AC-driven LED lighting applications. LED strobe problem

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