led drive circuit

Abstract

The invention provides an LED driver circuit. The LED driver circuit comprises an AC input end, a half-wave rectifying circuit, an output rectifying filtering circuit, a control module, power inductors and a switch unit, wherein the AC input end is used for inputting an alternating voltage, the half-wave rectifying circuit is used for converting the alternating voltage into a half-wave alternating voltage, the output rectifying filtering circuit is used for providing a stable drive current for an LED, the power inductors are connected with the two ends of the output rectifying filtering circuit in parallel, the switch unit is used for disconnecting or connecting the output end of the half-wave rectifying circuit and the input end of the output rectifying filtering circuit, the AC input end, the half-wave rectifying circuit, the switch unit and the output rectifying filtering circuit are connected in sequence, and the control module is respectively connected with the control end of the switch unit and the input end of the output rectifying filtering circuit, and is further coupled with the power inductors. The LED driver circuit has the advantages that accuracy of the output current is improved, and the lineation / load regulation rate is increased. In addition, due to the control mode adopted by a driver, the number of higher-harmonic components at the AC input end can be effectively reduced, and the THD of a system is reduced.

Description

technical field [0001] The invention relates to the field of power drive circuits, in particular to an LED drive circuit. Background technique [0002] Since the LED driving circuit has the advantages of low cost and simple system, its application in various AC-DC lighting products has attracted more and more attention. As energy saving and environmental protection are getting more and more attention around the world, people’s requirements for power factor PF and total harmonic distortion THD of various power supply products, including LED lighting products, are also increasing. It is very important in application. [0003] Such as Figure 4 As shown, the traditional active PFC non-isolated LED drive circuit system adopts buck-boost architecture. The LED drive circuit includes a rectifier circuit 101, an inductor 102, a controller 100, a switch 104, a resistor Rcs, an output diode D1, an output filter capacitor C1, etc., and the auxiliary winding 103 and the power supply n...

AI Technical Summary

Problems solved by technology

[0007] The output current of the LED driver circuit I O with the on-time of switch 104 T ON and off time T OFF It is related to the measured value and related to the peak voltage sampling, which will bring errors, which will affect the output accuracy and linear / load regulation

[0008] In addition, the input current of the AC input terminal of this kind of driving circuit contains high-order harmonic components, and the total harmonic distortion THD of the system is relatively high.

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