Driving circuit and method for powering light emitting diode light source, power converter

Abstract

The invention provides a driving circuit, a method and a power converter for powering a light emitting diode light source. The driving circuit includes: a voltage filter, a transformer and a controller. The voltage filter receives and filters the input voltage to provide a stable voltage; the transformer converts the stable voltage into an output voltage to supply power to the light source; the controller generates a driving signal to make the switch work alternately in the first state and the second state, and the controller controls the the duration of the first state and the duration of the second state such that the input current decreases to a preset value in the second state and increases from the preset value to a peak value proportional to the input voltage in the first state, The controller controls the ratio between the duration of the first state and the duration of the second state to adjust the output current flowing through the light source to a target value. The invention improves the current control accuracy, corrects the power factor of the driving circuit, improves the power supply quality, and reduces the horizontal frequency interference of the light source.

Description

technical field [0001] The invention relates to a driving circuit, in particular to a driving circuit and method for powering a light emitting diode light source, and a power converter. Background technique [0002] figure 1 Shown is a block diagram of a conventional light source driving circuit 100 . The driving circuit 100 is used to drive light sources such as LED strings 108 . The power supply 102 provides the input voltage V IN Provide power to the drive circuit 100 . The driving circuit 100 includes a buck converter that provides a converted voltage VOUT to the LED string 108 under the control of the controller 104 . The buck converter includes a diode 114 , an inductor 112 , a capacitor 116 and a switch 106 . Resistor 110 is connected in series with switch 106 . When the switch 106 is on, the resistor 110 is coupled with the inductor 112 and the LED string 108 to generate a feedback signal indicative of the current flowing through the inductor 112 . When the sw...

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Problems solved by technology

However, the average current flowing through the inductor 112 and the LED chain 108 will be affected by the inductance value of the inductor 112, the input voltage V IN and the influence of the voltage VOUT across the LED chain 108, so it is difficult to precisely control the average current flowing through the inductor 112 (that is, the average current flowing through the LED chain 108)

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