Constant voltage output switching power supply device with high power factor and control method thereof

Abstract

The invention discloses a constant voltage output switching power supply with a high power factor, which is composed of a rectifying and filtering circuit, a power converter, a control circuit, an output voltage feedback circuit, an inductive current zero-crossing feedback circuit and a chip power supply circuit. The constant voltage output switching power supply is characterized in that alternating current is inputted and converted into direct current through the rectifying and filtering circuit, the direct current is inputted into the power converter, the direct current is outputted to a load circuit from the power converter, then detection is carried out on a main power circuit through the output voltage feedback circuit, the inductive current zero-crossing feedback circuit and the chip power supply circuit, an acquired result is inputted into the control circuit so as to enable the control circuit to operate and obtain a control scheme, and output of the control circuit is transmitted to the power converter so as to perform control on the power converter. According to the constant voltage output power supply system with a high power factor, the turn-on time of a power switch tube is controlled to be constant through design of the control circuit and the feedback circuit; constant voltage output can be achieved in a full voltage range, and a high power factor can be ensured.

Description

technical field [0001] The invention relates to the technical field of switching power supplies, in particular to a constant voltage output power supply device and a control circuit thereof. [0002] technical background [0003] There are certain requirements for the power factor of the switching power supply connected to the AC grid, because if the power factor is not enough, it will cause a certain degree of pollution to the grid. The IEC International Electrotechnical Commission has put forward clear harmonic requirements for lighting fixtures, namely the IEC61000-3-2 standard. Judging from the actual application situation, the requirements for power factor are mostly higher than the standard regulations. [0004] The closest prior art of the present invention: publication number: CN102290997A, publication date: 2011-12-21, name: a constant voltage output control circuit and a switching power supply of a switching power supply controller, providing a constant voltage out...

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Problems solved by technology

Publication number: CN102904431A, public date: 2013-01-30, name: a switching power supply and its constant voltage output controller. The constant voltage output controller of the switch, the voltage sampling amplifier module and the pulse width modulation module simplifies the circuit structure of the switching power supply, reduces the cost, and can stably and reliably realize periodic modulation on the output voltage of the output stage load driving circuit to The load realizes constant voltage output, which solves the problems of poor system stability and reliability, complex circuit structure and high cost in the prior art

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