Constant-current output circuit for improving power factor correction efficiency and power supply

Abstract

The invention relates to a constant-current output circuit for improving power factor correction efficiency and a power supply. The constant-current output circuit comprises a rectification circuit, aPFC circuit, a half-bridge resonant circuit and a detection control circuit, wherein the rectification circuit is connected with a mains supply and is used for receiving an alternating current and rectifying the alternating current to a DC voltage, the PFC circuit is connected with the rectification circuit and is used for receiving and correcting the DC voltage and outputting a PFC voltage, thehalf-bridge resonant circuit is connected with the PFC circuit and is used for receiving the PFC voltage and outputting an output voltage according to the PFC circuit, the detection control circuit isconnected with an input end of the rectification circuit and a control end of the PFC circuit, the detection control circuit is used for outputting a voltage adjustment signal to the control end of the PFC circuit when the mains supply is lower than a preset value, and the PFC circuit is used for receiving the voltage adjusting signal and reducing an output voltage of the PFC circuit according tothe voltage adjustment signal. The output voltage of the PFC circuit can be rapidly reduced when the input voltage of the mains supply is lower than the preset value, the internal loss of the PFC circuit is reduced, and the efficiency of the PFC circuit is improved.

Description

Technical field [0001] The present invention relates to the technical field of power supplies, and more specifically, to a constant current output circuit and a power supply that improve the efficiency of power factor correction. Background technique [0002] LED light source has the characteristics of high efficiency, energy saving, environmental protection, long life, easy maintenance, etc., and is widely used in various fields such as tone green lighting and indoor and outdoor lighting. Based on the characteristics of the LED light source itself, it must be powered by a constant current source. Therefore, there is a demand for high-efficiency constant current drive power LED applications. [0003] According to the traditional circuit design, high power factor can be achieved by installing a power factor correction circuit (PFC circuit) in the driving power supply. However, for low voltage input, the PFC loss of the above power factor correction circuit is very large. At this tim...

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Problems solved by technology

[0003] According to the traditional circuit design, to obtain high power factor can be achieved by setting a power factor correction circuit (PFC circuit) in the drive power supply, but for low voltage input, the PFC loss of the above power factor correction circuit is very large, at this time, It is necessary to increase the power device and increase the heat sink to reduce the PFC loss, which not only increases the volume of the power supply, but also increases the cost and the efficiency of the whole machine is also low, which is not conducive to the purpose of green energy saving of LED products

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