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Control circuit with frequency regulation to reduce power supply converter electro-magnetic interference

A power converter and control circuit technology, applied in the direction of conversion equipment with intermediate conversion to AC, can solve the problem of insufficient electromagnetic interference effect, and achieve the effect of reducing electromagnetic interference

Active Publication Date: 2007-06-13
SYST GEN
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, when the switching frequency is set according to different applications, the effect of reducing electromagnetic interference will not be obvious.

Method used

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  • Control circuit with frequency regulation to reduce power supply converter electro-magnetic interference
  • Control circuit with frequency regulation to reduce power supply converter electro-magnetic interference
  • Control circuit with frequency regulation to reduce power supply converter electro-magnetic interference

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Embodiment Construction

[0094] FIG. 1 illustrates a conventional power converter. A control circuit 10 is coupled to a feedback circuit 50 to generate a switching signal V SW To adjust the output of the power converter, the feedback circuit 50 is coupled to the output of the power converter to generate a feedback signal V FB . where the switching signal V SW is in accordance with the feedback signal V FB And change. A switching current I of a transformer 30 P is converted into a switching current signal V through a sense resistor 40 S . The switching current signal V S provided to the control circuit 10 to generate the switching signal V SW .

[0095] FIG. 2 is a circuit diagram illustrating the control circuit 10 of the present invention. In the control circuit 10 , a switching circuit includes comparators 71 , 72 , flip-flop 75 , inverter 70 , AND gates 73 , 79 , diode 80 and resistors 90 , 91 , 92 , 93 . The resistor 90 is used to pull up a feedback terminal FB. The feedback terminal F...

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PUM

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Abstract

The control circuit is in use for reducing electromagnetic interference of a power supply converter. Being coupled to a feedback circuit, a switching circuit is in use for generating switch signal to adjust an output of the power supply converter. A first oscillator is in use for deciding switching frequency of a switch signal. Being coupled to the first oscillator, a second oscillator is in use for modulating switching frequency of the switch signal in order to reduce electromagnetic interference. A digital control resistor is in use for attenuating a feedback signal from a feedback circuit. Output of the second oscillator is coupled the digital control resistor in order to control resistance value of the digital control resistor. Thus, when switching frequency is modulated, output power and output voltage can be kept a fixed value.

Description

technical field [0001] The present invention relates to a power converter, and in particular to a control of a switching power converter. Background technique [0002] A power converter is used to convert an unregulated power source into a regulated voltage or current. FIG. 1 shows a conventional power converter, wherein a control circuit 10 includes a frequency setting terminal RT, a feedback terminal FB, a switching output terminal SW and a current sensing terminal VS, wherein the control circuit 10 generates A switching signal V SW , used to control a transistor 20 to switch a transformer 30 . A resistor 40 is used to sense a switching current I of the transformer 30 P to switch control. A resistor 45 is used to determine a switching frequency of the control circuit 10 . The feedback terminal FB of the control circuit 10 is connected to an output of a feedback circuit 50 . The feedback circuit 50 is coupled to the output of the power converter to generate a feedback...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M3/28
Inventor 杨大勇
Owner SYST GEN