Driving circuit and method for providing power to led light source, and power converter

Abstract

The invention provides a driving circuit and method for providing power to an LED light source, and a power converter. The driving circuit comprises a voltage filter, a transformer and a controller. The voltage filter receives and filters an input voltage to provide a stable voltage. The transformer converts the stable voltage into an output voltage to provide power to a light source. The controller generates a driving signal to make a switch work alternatively between a first state and a second state. The controller controls time durations of the first state and the second state, such that an input current decreases to a predetermined level during the second state and increases to a peak level proportional to the input voltage during the first state. The controller controls the ratio of time in the first state to time in the second state to adjust an output current flowing through the light source to a target level. According to the invention, the current control precision is improved, power factors of the driving circuit are corrected, the quality of power supply is improved, and line frequency interference of lighting of the light source is minimized.

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 driving 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 ...

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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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