Non-destructive absorption circuit of active PFC circuit

Abstract

The present invention relates to the technical field of circuit structures, in particular to a non-destructive absorption circuit of an active PFC circuit. The non-destructive absorption circuit includes a switching transistor Q1, a capacitor C2, a capacitor C3, a capacitor C4, a diode D1, a diode D2, a diode D3, a diode D4, a resistor R2, an inductor L2, and a winding L1. A drain of the switchingtransistor Q1 is respectively connected to one end of the capacitor C3, an anode of the diode D4, and the winding L1. The diode D4 is connected to the diode D3 in parallel. The capacitor C3 is connected to the diode D3 and the inductor L2. The inductor L2 is connected to the diode D1. The diode D1 is respectively connected to the diode D2 and resistor R2. In the present invention, an interferencesource generated when the power switching transistor works can be better reduced, so that an EMI circuit is simplified, a voltage stress of the power switching transistor is reduced, output efficiency of the whole machine is improved. The circuit is simple to implement with an excellent effect and high reliability.

Description

technical field [0001] The invention relates to the technical field of circuit structures, in particular to a non-destructive absorption circuit of an active PFC circuit. Background technique [0002] At present, under the condition that switching power supply has higher and higher requirements on power factor PF, the PFC circuit of switching power supply needs to use active PFC circuit to achieve higher PF value, and the power switch tube of active PFC circuit works at high frequency On -Off state of fast cycle switching, DV / DT and DI / DT are changing rapidly, so for EMI, the PFC power switch is not only the main interference source of electric field coupling, but also the main interference source of magnetic field coupling, plus the PCB on the The parasitic inductance will generate a peak voltage between the D pole and the S pole when the power switch tube is turned off. The larger the parasitic inductance will be, the higher the peak voltage will be. The traditional method...

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Problems solved by technology

[0002] At present, under the condition that switching power supply has higher and higher requirements on power factor PF, the PFC circuit of switching power supply needs to use active PFC circuit to achieve higher PF value, and the power switch tube of active PFC circuit works at high frequency On -Off state of fast cycle switching, DV / DT and DI / DT are changing rapidly, so for EMI, the PFC power switch is not only the main interference source of electric field coupling, but also the main interference source of magnetic field coupling, plus the PCB on the The parasitic inductance will generate a peak voltage between the D pole and the S pole when the power switch tube is turned off. The larger the parasitic inductance will be, the higher the peak voltage will be. The traditional method is to connect the D pole and the S pole of the power switch tube in parallel. A capacitor absorbs the peak voltage caused by the parasitic inductance of the PCB when the power switch tube is turned off, but this method will cause loss and reduce the output efficiency of the whole machine, and the EMI interference will not achieve the best effect

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