crm buck-flyback pfc converter with constant frequency control

A converter and filter technology, applied in control/regulation systems, output power conversion devices, DC power input conversion to DC power output, etc., can solve the problem of large switching frequency conversion range, complex EMI design, low power factor, etc. problem, to achieve the effect of PF improvement, efficiency improvement and output voltage ripple reduction
CN110518818BActive Publication Date: 2021-11-09NANJING UNIV OF SCI & TECH
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
NANJING UNIV OF SCI & TECH
Publication Date
2021-11-09

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Abstract

The invention provides a CRM step-down-flyback PFC converter adopting constant frequency control, comprising a main power circuit, an input voltage digital feedforward circuit, an output voltage differential circuit, a feedback circuit, a state judgment circuit, a drive signal generation circuit, Comparing and multiplying circuits. The present invention introduces an input voltage digital feedforward circuit, an input voltage comparison circuit and a gating circuit to realize a double-fixed-frequency control mode, so that the switching frequencies of the switching tubes of the converter in the Buck stage and the Flyback stage are kept at different constant values ​​respectively.
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Description

technical field

[0001] The invention relates to an AC / DC converter technology, in particular to a constant frequency controlled CRM step-down-flyback PFC converter. Background technique

[0002] Due to problems such as input current dead zone and switching tube floating ground, it is difficult for the traditional BuckPFC converter to meet the design technical requirements in many applications. In order to solve these problems, a buck-flyback PFC converter was proposed, which combines the Buck topology with the Flyback topology. When the input voltage is greater than the output voltage, the Buck topology works. When the input voltage is less than the output voltage, the Flyback Topology works. However, the traditional CRM buck-flyback PFC converter adopts constant on-time control. When the two topologies of the converter work, the on-time is equal, so that the switching frequency of the switching tube in the second half of the power frequency cycle of this control mode The ...

Claims

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