Control method of buck PFC (power factor correction)

A control method and control circuit technology, applied in control/regulation systems, output power conversion devices, instruments, etc., can solve problems such as complex circuits, poor circuit conversion efficiency, and insufficient circuit efficiency, and achieve simple and easy topology. The effect of realization and practicality
CN103296876AActive Publication Date: 2013-09-11MORNSUN GUANGZHOU SCI & TECH
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Patent Information

Authority / Receiving Office
CN ยท China
Current Assignee / Owner
MORNSUN GUANGZHOU SCI & TECH
Publication Date
2013-09-11

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Abstract

The invention discloses a control method of buck PFC (power factor correction). A source of an N-MOS (N-channel metal oxide semiconductor) tube in a flyback circuit is connected to a positive output of an output end. A series loop of a first inductance and a second capacitor is used as a demagnetization loop. When the N-MOS tube in the flyback circuit is on to excite a transformer, exciting current can power a load directly. When the N-MOS tube in the flyback circuit is off, the load is powered by the flyback output circuit, and a second primary side winding provides auxiliary power. During flyback, a voltage detecting control circuit 102 indirectly detects output voltage of a PFC circuit by detecting induced voltage of the second primary side winding, PWM (pulse-width modulation) duty ratio of pulse direct current at the next cycle is changed, and stable voltage output of the PFC circuit is achieved. By the control method, circuit topology is simplified, and circuits are easy to implement and practical.
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Description

technical field

[0001] The invention relates to an AC-DC circuit, in particular to an AC-DC converter for step-down power factor correction. Background technique

[0002] Both industrial and civil use often need to change the AC voltage of various grids into DC, or even isolated DC. With the further requirements of the national standard for the power factor of electrical appliances, at present, switching power supplies with power consumption above 75W have a power factor. Requirements, that is, the working current waveform of the circuit is basically the same as the voltage waveform.

[0003] At present, a power factor correction circuit has been adopted to solve this problem. The power factor correction circuit is referred to as a PFC circuit for short, which is an abbreviation of Power Factor Correction.

[0004] Note: The 75W data comes from the Chinese national standard GB17625.1-1998, named "Limits of Harmonic Current from Low-Voltage Electrical and Electronic Equipmen...

Claims

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