CN100468936C - Novel synchronous rectifying self-driven circuit for resonant reset forward converter - Google Patents

Abstract

The present invention provides a synchronization rectifying self-driving circuit for a new resonant reset forward converter. The gate charging loop of the freewheeling tube S2 comprises an auxiliary inductor La, diode D1 and D3. The gate charging loop of the freewheeling tube S2 is via a control tube S3. During the primary side main switch tube Q1 turn-on time, a third auxiliary winding charges the auxiliary inductor; after the primary side main switch tube Q1 is turned off, the auxiliary inductor La charges the gate capicitor of the freewheeling tube S2 with peak value current to turn on the capacitor by which switching loss and conducting loss of diode in the tube S2 caused by slowly turning on of the freewheeling tube S2 in the synchronization rectifying self-driving circuit for the resonant reset forward converter can be prevented. Thus the defect of slowly establishing of secondary side freewheeling tube driving voltage can be overcome and the common mode conduction time of the secondary side rectifying tube and freewheeling tube can be shorter compared with other self-driving manners, the turn-on performance of the freewheeling tube S2 is also better than external driving.

Description

The synchronous commutation self-driving circuit of novel resonant reset forward converter

Technical field:

The present invention relates to a kind of synchronous commutation self-driving circuit of novel resonant reset forward converter.

Background technology:

For satisfying the demand for development of following modular power source, the application of synchronized commutation technique is indispensable in the resonant reset circuit, self-driven with respect to outer driving, have on the cost and power density on advantage; But the secondary transformer waveform of resonant reset forward circuit is a sine wave, and the voltage section of the having time on the transformer is no-voltage after the magnetic reset finishing, and secondary presents diode rectification state in the body, and loss is very big.Therefore the corresponding propositions of a lot of self-driven schemes [1], [2], [3], [4], they come from following documents and materials respectively: document [1] comes from: [1] Karl T Fronk, Derry.Synchronous rectifierdrive mechanism for resonant reset forward converters, US patent, 61881578B1,2001-1-30. document [2] comes from: [2] Gu Yilei, Huang Guisong, Zhang Jinfa. a kind of synchronous rectification driving circuit Proceedings of the CSEE 2005.3 of novelty, 25 (5): 74-78 document [3] comes from: [3] XiaoGao Xie J.M Zhang, ZhaoMingQian, An improved self-driven synchronous rectification for a resonant reset forwardconverter.IEEE APEC 2003, pp 348-351 document [4] comes from: self-driven scheme such as Fig. 1 of the synchronous rectification self-driving circuit CN 1564443A 2005-1-12. document [1] of what resonant reset forward converter for army building of [4] Luo Quanming, its most outstanding advantage has electric charge exactly and keeps function.When the main switch conducting of former limit, the voltage waveform of transformer secondary winding is a normal square-wave signal, and secondary synchronous rectifier is open-minded at once, and auxiliary tube S3 also opens the grid discharge loop that secondary continued flow tube S2 is provided simultaneously, and S2 turn-offs.When former limit main switch Q1 turn-offed, the input capacitance charging that the sine wave among the secondary winding voltage waveform of transformer such as Fig. 1 (a) is given drain-source electric capacity and the continued flow tube S2 of auxiliary tube S3 by diode was up to the crest voltage of sine wave; Then stop charging.The driving voltage waveform rate of climb of continued flow tube is too slow as can be seen, and drive loss and turn-on consumption will increase greatly in the modular power source of high frequency, and this will have a strong impact on module complete machine conversion efficiency.Self-driven scheme such as Fig. 2 of document [2], comparing with the scheme of document [1] only is exactly to have increased tertiary winding driving, solved output voltage and crossed low or output voltage when too high, the driving voltage problem of continued flow tube S2, but exist the S2 pipe to open slow-footed problem equally.Document [3] utilizes the driving voltage of output voltage as continued flow tube S2, and simple in structure, cost is low; But when the resonant reset forward converter circuit output voltage is lower than 5V or is higher than 20V, self-driven mode is then improper in the document [3], on the low side because of driving voltage, will influence the switch performance and the conducting resistance of metal-oxide-semiconductor, and present modular power source contains the characteristics of low-voltage, high-current usually; When output voltage is high, in the wide region input voltage, does and self-drivenly may damage metal-oxide-semiconductor, this has limited the application of the self-driven mode of this kind on engineering.Self-driven mode such as Fig. 4 of document [4], utilization is coupled as the voltage on the outputting inductance driving voltage of continued flow tube, compare with document [3], the restriction of no-output voltage, but because coupling inductance flows through bigger electric current, therefore have bigger power loss on the drive circuit of S2, and increased the design difficulty of circuit.

Summary of the invention:

The objective of the invention is to provide a kind of driving problems of synchronous commutation self-driving circuit to solve of resonant reset forward converter, the driving voltage that makes continued flow tube drive is set up rapidly, and this circuit structure is simple, reliable.

For achieving the above object, the gate pole charge circuit that the present invention proposes a kind of described continued flow tube S2 of synchronous commutation self-driving circuit of novel resonant reset forward converter comprises auxiliary induction La, diode D1, D3, and the gate pole discharge loop of described continued flow tube S2 discharges by control valve S3; During the main switch Q1 conducting of former limit, the 3rd auxiliary winding Na gives auxiliary induction La charging, when former limit main switch Q1 turn-offs, the gate pole electric capacity charging that auxiliary induction La gives continued flow tube S2 with peak current, continued flow tube S2 opens at once and has avoided in the synchronous commutation self-driving circuit of resonant reset forward converter because continued flow tube S2 opens the conduction loss of diode in the switching loss slowly brought and the body.

Set up shortcoming slowly owing to adopted this above-mentioned self-driven mode to overcome secondary continued flow tube S2 driving voltage, and the driving voltage of continued flow tube is kept by an interrupted buck-boost electronic circuit.

Than other self-driven mode, the weak point that the common-mode ON time that the rectifying tube S1 of this scheme secondary and continued flow tube S2 exist is come, simultaneously with outer drive compare continued flow tube to open performance also better.

Description of drawings:

Fig. 1 is first kind of embodiment circuit diagram of prior art resonant reset forward converter synchronous commutation self-driving circuit;

Fig. 1 (a) is first kind of embodiment key waveforms of prior art resonant reset forward converter synchronous commutation self-driving circuit analogous diagram;

Fig. 2 is second kind of embodiment circuit diagram of prior art resonant reset forward converter synchronous commutation self-driving circuit;

Fig. 3 is the third embodiment circuit diagram of prior art resonant reset forward converter synchronous commutation self-driving circuit;

Fig. 3 (a) is the third embodiment key waveforms of prior art resonant reset forward converter synchronous commutation self-driving circuit figure;

Fig. 4 is the 4th kind of embodiment circuit diagram of prior art resonant reset forward converter synchronous commutation self-driving circuit;

Fig. 5 is the novel resonant reset forward converter synchronous commutation self-driving circuit of a present invention embodiment circuit diagram;

Fig. 5 (a) is the novel resonant reset forward converter synchronous commutation self-driving circuit of the present invention embodiment key waveforms figure;

Fig. 5 (b) be the novel resonant reset forward converter synchronous commutation self-driving circuit of the present invention embodiment principle with outer drive ratio than oscillogram;

Embodiment:

Also the present invention is described in further detail in conjunction with the accompanying drawings below by specific embodiment.

Embodiment one: as shown in Figure 5, and a kind of novel resonant reset forward converter, main switch Q1, transformer Tr, resonant reset capacitor C 1, C2, rectifying tube S1, continued flow tube S2, control valve S3, the 3rd auxiliary winding Na, auxiliary induction La.The gate pole charging circuit of described synchronous freewheeling pipe S2 is made of auxiliary induction La, diode D1, continued flow tube S2, diode D3.The anode of the B terminating diode D1 of auxiliary induction, the negative electrode of diode D1 connects the gate pole of continued flow tube S2, and the source electrode of continued flow tube S2 connects the anode of diode D3, and the negative electrode of diode D3 connects the A end of auxiliary induction La.The gate pole discharge loop of described synchronous freewheeling pipe S2 is made of control valve S3, and the gate pole of control valve S3 connects the end of the same name of the 3rd auxiliary winding Na, and the source electrode of control valve S3 connects the different name end of the 3rd auxiliary winding Na.The gate pole of the gate pole of secondary synchronous rectifier S1 and control valve S3 is all received the end of the same name of the 3rd auxiliary winding Na, the B termination three end line pressurizers of auxiliary induction La, and this three end lines pressurizer provides accessory power supply for secondary.

Fig. 5 (a) then is the main waveform of each point in the circuit working, V _GS(Q1) be the driving voltage of former limit main switch Q1, V _GS(S1) be the driving voltage waveform of synchronous rectifier S1, i _LaBe the electric current of auxiliary induction La, V _GS(S2) be the driving voltage waveform of synchronous freewheeling pipe S2, i _Q1Be the current waveform of former limit main switch Q1, VQ1 is the terminal voltage waveform at main switch Q1 drain-source the two poles of the earth, former limit.

The operation principle of foregoing circuit:

At [t ₀-t ₁] stage: at t ₀Former limit main switch Q1 is open-minded constantly, and the electric current that flows through secondary rectifying tube S1 begins to increase, and the electric current of secondary continued flow tube S2 begins to reduce.Exciting curent begins linear rising, t ₁Afterflow constantly finishes.

At [t ₁-t ₂] stage: at t ₁Secondary rectifying tube S1 and secondary control valve are open-minded fully, and energy is directly passed to load by transformer, and exciting curent continues to rise; The electric current of secondary inductance La also begins to rise simultaneously:

$i_{\mathrm{La}}\left(t\right)=\frac{V_{\mathrm{Na}}}{L_a}\·(t-t_1)+i_{\mathrm{La}}\left(t_1\right)---\left(1\right)$

In the side circuit i _LaBe designed to the interrupter duty pattern, so other i _La(t ₁)=i _La(t0)=0, at t ₂Switch Q1 turn-offs constantly.

At [t ₂-t ₃] stage: this state Q1 turn-offs, switching tube junction capacitance C _SAnd C ₁Be recharged the discharge of continued flow tube S2 junction capacitance, inductance L _aElectric current from $i_{\mathrm{La}}{\left(t\right)|}_{\max }=\frac{V_{\mathrm{Na}}}{L_a}\·D\·T_S,$ And the electric current of inductance L a begins to give electric capacity charging between the drain-source of the input capacitance of continued flow tube S2 and control valve S3 with peak current, at t ₃The time V _GS(S2) voltage on equals V _G3Voltage, continued flow tube S2 conducting, this stage finishes.

At [t ₃-t ₄] stage: the leakage inductance of transformer continues to C1, C in this state _SCharging, this section resonance time is shorter; Inductance L _aElectric current begins to provide energy to the secondary accessory power supply, charges to C3.

At [t ₄-t ₅-t ₆] stage:

From t4 constantly, magnetizing inductance L _MBegin resonance with capacitor C 1, C2, the energy back on resonance holds is given power supply and transformer, finishes magnetic reset work;

At [t ₆-t ₇] stage: the rich resistance of transformer secondary both end voltage is zero during this period of time; Shown in Fig. 5 (B), as long as secondary control valve S3 is not open-minded, continued flow tube S2 can not turn-off, t ₇Be the beginning of next switch periods constantly

Open-minded at DTs stage secondary rectifying tube S1 and assist control pipe S3, the voltage V on the while tertiary winding _Na, through inductance L _a, behind D1, the S3, get back to the earth terminal of tertiary winding Na, this interval auxiliary induction L that gives _aCharging, promptly the La inductance has stored energy.In (1-D) Ts stage, control valve S3 turn-offs, and auxiliary induction La gives electric capacity charging between the drain-source of the input capacitance of continued flow tube S2 and control valve S3 with peak current simultaneously, works as V _GS(S2) voltage on is charged to V _C3In time, just stop to charge; Go back dump energy in the auxiliary induction, the necessary afterflow of inductive current will form continuous current circuit by La-D2-C3-D3-La.

The present invention should note in Fig. 5 (b), V _G1Be the metal-oxide-semiconductor driving voltage rising waveform of novel self-driven mode, V _G1Be outer type of drive metal-oxide-semiconductor driving voltage rising waveform; V _G1Drive current waveform be I _La, V _G2Drive current waveform be I _SourceTo V _G1, V _G2Select same metal-oxide-semiconductor, V _G1The Muller level is established as t ₁-t ₀, VG ₂The Muller level is established as t ₂-t ₀

By $\frac{1}{2}\·C_{\mathrm{in}}\·{V_{\mathrm{Miller}}}^2=Q_G\·V_{\mathrm{Miller}}---\left(2\right)$

Can get equation: $\frac{1}{2}\&CenterDot;C_{\mathrm{in}}\&CenterDot;V_G={\mathrm{<figure-callout\; id="1"\; label="I\; G"\; filenames="C200710008815E00071.png,C200710008815E00072.png"\; state="\{\{state\}\}">I</figure-callout>}}_G\&CenterDot;\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="C200710008815E00071.png,C200710008815E00072.png"\; state="\{\{state\}\}">t</figure-callout>}}_1={\mathrm{<figure-callout\; id="2"\; label="I\; G"\; filenames="C200710008815E00071.png,C200710008815E00083.png"\; state="\{\{state\}\}">I</figure-callout>}}_G\&CenterDot;\mathrm{\&Delta;}{t}_2---\left(3\right)$

In Fig. 5 (b), ${\mathrm{<figure-callout\; id="1"\; label="I\; G"\; filenames="C200710008815E00071.png,C200710008815E00072.png"\; state="\{\{state\}\}">I</figure-callout>}}_G=\frac{I_{\mathrm{peak}}+I_{\mathrm{<figure-callout\; id="1"\; label="La"\; filenames="C200710008815E00071.png,C200710008815E00072.png"\; state="\{\{state\}\}">La</figure-callout>}1}}{2},$ ${\mathrm{<figure-callout\; id="2"\; label="I\; G"\; filenames="C200710008815E00071.png,C200710008815E00083.png"\; state="\{\{state\}\}">I</figure-callout>}}_G=\frac{I_{\mathrm{<figure-callout\; id="1"\; label="Sour"\; filenames="C200710008815E00071.png,C200710008815E00072.png"\; state="\{\{state\}\}">Sour</figure-callout>}1}+0}{2},$ Δt ₁＝t ₁-t ₀，Δt ₂＝t ₂-t ₀；

Because I _G1I _G2So, Δ t ₁＜Δ t ₂, illustrate that metal-oxide-semiconductor has the very fast speed of opening under the novel self-driven mode, and open speed through the metal-oxide-semiconductor under experimental verification this novel self-driven mode and be better than outer driving really.

Claims (6)

1. the synchronous commutation self-driving circuit of a resonant reset forward converter, comprise main switch Q1, synchronous rectifier S1, synchronous freewheeling pipe S2, the 3rd auxiliary winding Na, auxiliary induction La, control valve S3, NPN transistor Q2, voltage-stabiliser tube Z1, capacitor C 3, C4, diode D1, D2, D3, D4, it is characterized in that: the driving energy source of synchronous freewheeling pipe S2 has overcome synchronous freewheeling pipe S2 and opened problem slowly, and the driving voltage of synchronous freewheeling pipe S2 is stablized by the voltage of C3 in the storage power of auxiliary induction La; The gate pole charging circuit of synchronous freewheeling pipe S2 is made of auxiliary induction La, diode D1, synchronous freewheeling pipe S2, diode D3; The anode of the terminating diode D4 of the same name of the 3rd auxiliary winding Na, the negative electrode of diode D4 connects the A end of auxiliary induction La, the anode of the B terminating diode D1 of auxiliary induction La, the anode of diode D1 connects the gate pole of synchronous freewheeling pipe S2, the source electrode of synchronous freewheeling pipe S2 connects the anode of D3, and the negative electrode of D3 connects the A end of auxiliary induction La; The dump energy of auxiliary induction La is put on the capacitor C 3 through diode D2, diode D3.

2. the synchronous commutation self-driving circuit of resonant reset forward converter according to claim 1, it is characterized in that: the gate pole discharge loop of described synchronous freewheeling pipe S2 is made of control valve S3.

3. the synchronous commutation self-driving circuit of resonant reset forward converter according to claim 2, it is characterized in that: described control valve S3 is a N type small-power field effect transistor, the drain electrode of control valve S3 connects the gate pole of synchronous freewheeling pipe S2, the gate pole of control valve S3 connects the end of the same name of the 3rd auxiliary winding Na, and the source electrode of control valve S3 connects the source electrode of synchronous freewheeling pipe S2 and the different name end of the 3rd auxiliary winding Na.

4. the synchronous commutation self-driving circuit of resonant reset forward converter according to claim 1, it is characterized in that: the anode of the B terminating diode D2 of described auxiliary induction La, the negative electrode of diode D2 connects an end of capacitor C 3, the anode of another termination D3 of capacitor C 3, the anode of D3 connects secondary ground.

5. the synchronous commutation self-driving circuit of resonant reset forward converter according to claim 4, it is characterized in that: the negative electrode of described diode D2 connects the collector electrode of NPN transistor Q2, the base stage of NPN transistor Q2 connects the negative electrode of voltage-stabiliser tube Z1, the anode of voltage-stabiliser tube Z1 connects the anode of diode D3, parallel resistance R1 between the base stage of NPN transistor Q2 and the collector electrode, capacitor C 4 provides accessory power supply for secondary.

6. the synchronous commutation self-driving circuit of resonant reset forward converter according to claim 5 is characterized in that: described C4 is connected in parallel between the anode of the emitter of transistor Q2 and D3, and the anode of D3 is connected with the source electrode of synchronous freewheeling pipe S2.

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