CN1558539A - Transformer clamping zero voltage switch three level full bridge converter and its expansion circuit - Google Patents

Abstract

A transformer clamping zero voltage switch three level full bridge converter comprises a D.C. voltage and input dividing potential drop capacitor, a switching tube chopper circuit, a transformer isolating circuit, a filtering circuit and a DC voltage follower circuit, wherein the switching tube chopper circuit forms a front bridge arm through four switching tubes and a lagging bridge arm through the other four switching tubes, thus realizing the voltage stress of the switching tubes at half of the input voltage.

Description

Transformer clamping Zero voltage switch three lever full-bridge converter and expanded circuit thereof

Technical field

Transformer clamping Zero voltage switch three lever full-bridge converter of the present invention and expanded circuit thereof belong to power electronic system straight/DC converter.

Background technology

In current society, electricity is closely related with people's life, and power consumption equipment is seen everywhere.In numerous power consumption equipments, power supply is a requisite part, and the required power supply of general power consumption equipment can be divided into two kinds: a kind of is AC power, and a kind of is DC power supply.Alternating current can directly obtain from the Alternating Current Power Supply electrical network, or the alternating current in the electrical network is obtained after by the transformer transformation, also can be reverse into alternating current or the like by inverter by direct current.The simplest obtain manner of direct current is to be filtered into direct current after the AC rectification, but in order to obtain reliable and stable direct current, just must adopt converter, and converter generally refers to directly/DC converter (DC/DC Converters).If input is an alternating current, is exactly friendship/DC converter (AC/DCConverters) so, this converter generally is earlier AC rectification to be become direct current, and then carries out straight/straight conversion.Directly/circuit topology of DC converter is multifarious, mainly can be divided into two classes: the one, input, output are not isolated, this quasi-converter is common Buck (step-down), Boost (boosting), Cuk circuit such as (bucks) and the circuit that derives for the working condition of improving circuit.The 2nd, input, output band are isolated, this quasi-converter is common Flyback (anti-swash), Forward (normal shock), Push-Pull (recommending), Half-Bridge (half-bridge), Full-Bridge circuit such as (full-bridges), and the circuit that derives for the working condition of improving circuit.Power supply in present many power consumption equipments all requires input, output to isolate, therefore second quasi-converter use more extensive, this quasi-converter has certain general character, generally can be divided into following six parts: the input of (1) direct voltage; (2) switching tube copped wave; (3) transformer isolation; (4) diode (or switching tube) rectification; (5) inductance, capacitor filtering; (6) direct voltage output.Below with traditional full-bridge straight/DC converter (FB DC/DC Converter) circuit illustrated these six parts, sees Fig. 1.The working condition of this circuit can be briefly described as follows: switching tube (Q ₁, Q ₂, Q ₃, Q ₄) two operating states are arranged, promptly open or turn-off.As (Q ₁, Q ₄) or (Q ₂, Q ₃) when opening, energy is transmitted to secondary in the former limit of transformer, transformer secondary rectifier diode D _R1Or D _R2Conducting, the voltage after the rectification is through inductance L _o, capacitor C _oBecome direct current supply load R after the filtering _oAs (Q ₁, Q ₂, Q ₃, Q ₄) when all turn-offing, energy is not transmitted to secondary in the former limit of transformer.

That band is isolated is straight/and the DC converter application scenario is very wide, and different occasions requires also different.And the circuit topology that converter is selected for use is also according to the difference of application scenario and difference generally has two to select foundation for use, the one, and according to the height of input voltage, the 2nd, according to the size of power output.These two conditional decisions select the quota of main power tube (switching tube) for use.Now, in order to improve power factor, usually adopt power factor correction (PFC) technology, the output dc voltage of three-phase pfc converter is generally 760V～800V, sometimes even up to 1000V, this makes the very difficulty that the selection of switching tube of DC converter of back level becomes.In order to address this problem, the Pinheiro of Brazil in 1992 has proposed three-level DC converter of zero-voltage switch (Zero-Voltage-Switching Three-Level Converter, ZVS TL converter), the switch tube voltage stress of this converter is half of input direct voltage.Subsequently, many scholars have done a large amount of research in this respect, delivered one after another about solve high input voltage straight/article of DC converter, these converters have a common characteristic mostly, utilize input dividing potential drop electric capacity to carry out dividing potential drop exactly, to reduce the voltage stress on the switching tube, input dividing potential drop electric capacity is interleaved power.These converters can be referred to as multi-level converter.Wherein, more typical circuit is Zero-voltage-switching PWM three-level converter (ZVSPWM TL Converter), see Fig. 2, wherein the voltage stress of switching tube is half of input voltage in this circuit, utilizes the junction capacitance of the leakage inductance (or outer coilloading) of transformer and switching tube to realize the ZVS of switching tube simultaneously.

Mention above, input dividing potential drop electric capacity is interleaved power, and this just brings a problem, promptly can not guarantee the stable of two input capacitance midpoint potentials.The solution of this problem is to strengthen the input capacitance capacity, reduces through-put power.Therefore, during this quasi-converter is widely used in, in the low power application scenario.

In some occasion, the voltage of input is very high, and the power of output is very big again, locomotive input voltage as subway, light rail car is direct current 1700V, and the voltage request of the many power consumption equipments on the locomotive is three-phase alternating current 380V, and demand power reaches up to a hundred kilowatts, therefore, direct voltage will carry out conversion.The step-down scheme more typically has full-bridge circuit, and must to select withstand voltage be the switching tube of 3300V but big capacity can be dealt with the switching tube of 1700V input, and this switching tube is very expensive.

Summary of the invention

The objective of the invention is at above-mentioned the deficiencies in the prior art, develop and a kind ofly can guarantee that two and two above input capacitance midpoint potentials are stable, can use the Zero voltage switch three lever converter and the expanded circuit thereof of common withstand voltage switching tube.

For achieving the above object, transformer clamping Zero voltage switch three lever full-bridge converter of the present invention and expanded circuit thereof are to adopt the transformer clamping technology, it has alleviated the pressure of input dividing potential drop electric capacity, input dividing potential drop electric capacity no longer participates in the transmission of main power, the transformer energy delivered directly obtains from input DC power, rely on the clamp of transformer, voltage automatically equalizing voltage on the dividing potential drop electric capacity, thereby the voltage stress that has guaranteed switching tube is a m/(m=2 of input voltage, 3,4,5......).

It is to comprise that the direct voltage input circuit is connected in input dividing potential drop electric capacity and switching tube chopper circuit that transformer clamping Zero voltage switch three lever full-bridge converter is formed, its output is connected in the transformer isolation circuit, the output of transformer isolation circuit is connected in dc voltage output circuit at last through diode rectifier circuit and inductance capacitor filtering circuit.Be characterized in the composition of described switching tube chopper circuit and transformer isolation circuit.The switching tube chopper circuit is the series connection of two full-bridge circuits, 1st, the 3rd, the 5th and the 7th four switching tubes are connected in parallel on the series circuit two ends of two dividing potential drop input capacitances in the positive and negative two ends after the forward series connection successively, and connect mid point and the mid point of connecting of two dividing potential drop input capacitances of the 1st, the 3 two switching tube and the 5th, the 7 two switching tube is connected to form the leading-bridge of full-bridge circuit; 2nd, in addition four switching tubes of the 4th, the 6th and the 8th are connected in parallel on the series circuit two ends of two dividing potential drop input capacitances in the positive and negative two ends after the forward series connection successively equally, and connect mid point and the mid point of connecting of two dividing potential drop input capacitances of the 2nd, the 4 two switching tube and the 6th, the 8 two switching tube is connected to form the lagging leg of full-bridge circuit.The former limit of the transformer of described transformer isolation circuit is wound with two windings that the number of turn is identical, the same inscription end of one of them winding is connected in the mid point of connecting of leading-bridge the 1st and the 3 two switching tube, different inscription end is connected in the mid point of connecting of lagging leg the 2nd and the 4 two switching tube, the same inscription end of another winding is connected in the mid point of connecting of leading-bridge the 5th and the 7 two switching tube, different inscription end is connected in the mid point of connecting of lagging leg the 6th and the 8 two switching tube, two windings of transformer secondary diode rectifier circuit that still is connected in respectively separately same as the prior art.

The present invention is on the basis of three level full-bridge converters, the dividing potential drop of connecting again electric capacity, the two ends of each dividing potential drop electric capacity connect one by two switching tubes series connection and other two full-bridge circuits that switching tube is connected and formed, and the output of each full-bridge circuit is connected in an all identical expanded circuit that former limit winding is constituted of its number of turn on the corresponding transformer that is wound on same transformer isolation circuit again.

Description of drawings

The traditional full-bridge of Fig. 1 is straight/the DC converter circuit theory diagrams

The Zero-voltage-switching PWM three level transformer principle figure that Fig. 2 is traditional

Fig. 3 transformer clamping Zero voltage switch three lever full-bridge converter schematic diagram

Fig. 4 transformer clamping full-bridge converter of zero-voltage switch of the present invention expanded circuit schematic diagram

Several specific embodiment figure of Fig. 5 Fig. 4

Fig. 6 transformer clamping Zero voltage switch three lever full-bridge converter switching tube drive signal schematic diagram

The operation principle schematic diagram of Fig. 7 transformer clamping Zero voltage switch three lever full-bridge converter

Fig. 8 schematic equivalent circuit

The designation of Fig. 3～Fig. 8: Vin-direct voltage, C _I1, C _I2, C _In-dividing potential drop electric capacity, Q ₁～Q ₈-switching tube, D ₁～D ₈-fly-wheel diode, C ₁～C ₈-electric capacity, N _P1, N _P2, N _PnThe former limit of-transformer winding, N _S1, N _S2-transformer secondary winding, D _R1, D _R2-rectifier diode, Lo-filter inductance, Co-filter inductance, Ro-resistance, Vo-output voltage, FB-1, FB-2, FB-n-full-bridge circuit, t ₀～t ₈-switch periods, t _d-Dead Time, α-phase shifting angle, i _P1, i _P2-transformer primary current, i _S1, i _S2-transformer secondary current, Io-output current, E _pThe former limit of-transformer winding terminal voltage, r ₁-full-bridge the first half switching tube, lead, the former limit of transformer winding N _P1All-in resistance, r ₂-full-bridge the latter half switching tube, lead, the former limit of transformer winding N _P2All-in resistance.N=3 wherein, 4,5,6......

Embodiment

As shown in Figure 3, concrete composition of the present invention is, the output of direct voltage 1 is connected in input dividing potential drop electric capacity 2 and switching tube chopper circuit 3, its output is connected in the former limit of transformer of transformer isolation circuit 4, the output of transformer isolation circuit 4 is connected in dc voltage output circuit 6 at last through diode rectifier circuit and inductance capacitor filtering circuit 5.By Fig. 1, Fig. 2, Fig. 3 as can be known, inventive point of the present invention is switching tube chopper circuit 3 and transformer isolation circuit 4, and wherein the concrete composition of switching tube chopper circuit 3 is by four switching tube Q of the 1st, the 3rd, the 5th and the 7th ₁, Q ₃, Q ₅, Q ₇Positive and negative two ends after the forward series connection are connected in parallel on two dividing potential drop input capacitance C successively _I1With C _I2The series circuit two ends, and the 3rd switching tube Q ₃With the 5th switching tube Q ₅Series connection mid point and two dividing potential drop input capacitance C _I1With C _I2The series connection mid point be connected to form the leading-bridge of full-bridge circuit; 2nd, four switching tube Q in addition of the 4th, the 6th and the 8th ₂, Q ₄, Q ₆, Q ₈Positive and negative two ends after the forward series connection are connected in parallel on two dividing potential drop input capacitance C equally successively _I1With C _I2The series circuit two ends, the 4th switching tube Q ₄With the 6th switching tube Q ₆Series connection mid point and two dividing potential drop input capacitance C _I1With C _I2The series connection mid point be connected to form the lagging leg of full-bridge circuit.Two the winding N in the former limit of the transformer of described transformer isolation circuit 4 _P1, N _P2On the same magnetic core of transformer, the number of turn of two windings is identical, one of them winding N _P1Same inscription end be connected in leading-bridge the 1st switching tube Q ₁With the 3rd switching tube Q ₃The series connection mid point, different inscription end is connected in lagging leg the 2nd switching tube Q ₂With the 4th switching tube Q ₄The series connection mid point, another winding N _P2Same inscription end be connected in leading-bridge the 5th switching tube Q ₅With the 7th switching tube Q ₇The series connection mid point, different inscription end is connected in lagging leg the 6th switching tube Q ₆With the 8th switching tube Q ₈The series connection mid point, constitute transformer clamping thus, two windings of transformer secondary diode rectifier circuit that still is connected in respectively separately same as the prior art.

Fig. 4 and Fig. 5 be expanded circuit schematic diagram of the present invention and implement illustration, and by Fig. 4 and Fig. 5 as can be known, expanded circuit of the present invention is on the basis of transformer clamping three level full-bridge converters, the dividing potential drop of connecting again capacitor C _In, each dividing potential drop capacitor C _InTwo ends connect a full-bridge circuit FB-n (n=3 who is connected and formed by two switching tube series connection and other two switching tubes, 4,5,6......) and the output of each full-bridge circuit FB-n be connected in an all identical former limit winding N of its number of turn on the corresponding transformer that is wound on same transformer isolation circuit 4 again _Pn(n=3,4,5, the 6......) expanded circuit of being formed.

Following elder generation carries out simple analysis to its operation principle, for the ease of theory analysis, only this converter of transformer clamping Zero voltage switch three lever full-bridge converter (n=2) is analyzed, see Fig. 3, the operation principle of transformer clamping full-bridge converter of zero-voltage switch expanded circuit (n＞2) and it are basic identical.Control circuit adopts traditional phase shifting control, (Q ₁, Q ₃, Q ₅, Q ₇) the composition leading-bridge, (Q ₂, ' Q ₄, Q ₆, Q ₈) the composition lagging leg.The drive signal of the switching tube on the brachium pontis correspondence position is identical, and the drive signal of switching tube is seen Fig. 6, t ₀～t ₈Be a switch periods, t _dBe Dead Time, α is a phase shifting angle.

Before analyzing, make the following assumptions earlier;

1) all switching tubes, inductance, electric capacity are desirable device

2) transformer leakage inductance is much smaller than output inductor Lo

3) the former secondary turn ratio of transformer is K:

$K=\frac{N_{p1}}{{\mathrm{<figure-callout\; id="1"\; label="N\; s"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">N</figure-callout>}}_s}=\frac{N_{p2}}{{\mathrm{<figure-callout\; id="2"\; label="N\; s"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">N</figure-callout>}}_s}=\frac{N_p}{N_s}$

4) switching tube Q ₁～Q ₈Shunt capacitance is Cr

5) input dividing potential drop capacitor C _I1=C _I2=C _Is

Below be the course of work of converter:

[1] at t ₀Constantly, switching tube Q ₁, Q ₅, Q ₄, Q ₈Conducting, input voltage source transmits energy, secondary rectifier diode D by the former limit of transformer to the transformer secondary _R1Conducting.See Fig. 7 (a).

[2] t ₀Constantly, turn-off Q simultaneously ₁, Q ₅, primary current i _P1, i _P2From Q ₁, Q ₅In transfer to C ₁, C ₃, C ₅, C ₇In the branch road, give C ₁, C ₅Charging, C simultaneously ₃, C ₇Discharged.Because C is arranged ₁, C ₃, C ₅, C ₇, Q ₁, Q ₅For no-voltage is turn-offed.Work as C ₃, C ₇On voltage drop to zero, Q ₃, Q ₇Anti-and diode D ₃, D ₇The nature conducting.See Fig. 7 (b).

[3] t ₁Constantly, open Q ₃, Q ₇Be that no-voltage is open-minded, the vanishing of transformer original edge voltage, primary current nature circulation.See Fig. 7 (c).

[4] t ₂Constantly turn-off Q simultaneously ₄, Q ₈, primary current is from Q ₄, Q ₈In transfer to C ₂, C ₄, C ₆, C ₈In the branch road, give C ₄, C ₈Charging, C simultaneously ₂, C ₆Discharged.Because C is arranged ₂, C ₄, C ₆, C ₈, Q ₄, Q ₈For no-voltage is turn-offed.See Fig. 7 (d).[5] work as C ₂, C ₆On voltage drop to zero after, diode D ₂, D ₆Conducting, the transformer primary current flows to input voltage, sees Fig. 7 (e).

[6] t ₃Constantly open Q simultaneously ₂, Q ₆, begin oppositely secondary rectifier diode D after primary current drops to zero _R2Conducting, D _R1Turn-off.Input voltage source transmits energy by the former limit of transformer to the transformer secondary.To t ₄Constantly turn-off Q ₃, Q ₇, converter enters down the work period half, and its course of work is similar to last half work period.

From top analysis as can be seen, in whole work period, dividing potential drop electric capacity does not participate in the transmission of energy, simultaneously because the clamp of the former limit of transformer winding, voltage on the dividing potential drop electric capacity can automatically equalizing voltage, thereby guarantees that voltage stress on the main power tube is half of input voltage.

Below the operation principle of three level full-bridge converter (n=2) transformer clampings is analyzed, the operation principle of expanded circuit (n＞2) and it are basic identical: so-called transformer clamping is the former limit of transformer winding N _P1, N _P2On same magnetic core, if winding N _P1, N _P2The number of turn is identical, so winding N _P1, N _P2It is identical that both end voltage keeps constantly.Converter work mainly is divided into three phases, and the one, energy is transmitted to secondary in the former limit of transformer; The 2nd, the former and deputy polygonal voltage of transformer is zero (converter is in nought state); The 3rd, the converter switches pipe carries out voltage transitions (ZVS).Wherein the three phases time very short, therefore can ignore its influence to dividing potential drop electric capacity, second stage dividing potential drop electric capacity does not participate in.Depend on first stage so whether dividing potential drop electric capacity can stablize (automatically equalizing voltage).

Phase I equivalent circuit Fig. 8, wherein r ₁Be full-bridge the first half switching tube, lead, the former limit of transformer winding N _P1All-in resistance, r ₂Be full-bridge the latter half switching tube, lead, the former limit of transformer winding N _P2All-in resistance, E _pBe transformer terminal voltage, transformer leakage inductance is very little, ignores transformer leakage inductance in this stage.

If input dividing potential drop electric capacity midpoint potential is disturbed, undulate quantity is Δ U _o, suppose that fluctuation causes the dividing potential drop capacitor C _I1On voltage be higher than capacitor C _I2Voltage.The transformer original edge voltage is E _P1, E _P2, secondary voltage is E _S1, E _S2The transformer primary current is i _P1, i _P2, secondary current is i _S1, i _S2

According to constant-linkage theorem:

${\mathrm{<figure-callout\; id="1"\; label="E\; p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">E</figure-callout>}}_p={\mathrm{<figure-callout\; id="1"\; label="N\; p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">N</figure-callout>}}_p\frac{\mathrm{d\&Phi;}}{\mathrm{dt}},$ ${\mathrm{<figure-callout\; id="2"\; label="E\; p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">E</figure-callout>}}_p={\mathrm{<figure-callout\; id="2"\; label="N\; p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">N</figure-callout>}}_p\frac{\mathrm{d\&Phi;}}{\mathrm{dt}}$

${\mathrm{<figure-callout\; id="1"\; label="E\; s"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">E</figure-callout>}}_s={\mathrm{<figure-callout\; id="1"\; label="N\; s"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">N</figure-callout>}}_s\frac{\mathrm{d\&Phi;}}{\mathrm{dt}},$ ${\mathrm{<figure-callout\; id="2"\; label="E\; s"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">E</figure-callout>}}_s={\mathrm{<figure-callout\; id="2"\; label="N\; s"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">N</figure-callout>}}_s\frac{\mathrm{d\&Phi;}}{\mathrm{dt}},$

Have: E _p=E _P1=E _P2=KE _S1=KE _S2(1)

N _p1*i _p1+N _p2*i _p2＝N _s1*i _s1+N _s2*i _s2

N _p*(i _p1+i _p2)＝N _s*(i _s1+i _s2)＝N _s*I _o

Have:

$i_{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">p</figure-callout>}1}+i_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">p</figure-callout>}2}=\frac{I_o}{K}----\left(2\right)$

Can get from the converter equivalent electric circuit:

$i_{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">p</figure-callout>}1}=\frac{\frac{1}{2}{V}_m+\mathrm{\&Delta;}{U}_o-E_p}{r_1}---\left(3\right)$

$i_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">p</figure-callout>}2}=\frac{\frac{1}{2}{V}_m-\mathrm{\&Delta;}{U}_o-E_p}{r_2}----\left(4\right)$

By formula (1), (2), (3), (4) can get:

$i_{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">p</figure-callout>}1}=\frac{r_2{I}_o}{K({\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+r_2)}+\frac{2\mathrm{\&Delta;}{U}_o}{{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+r_2}----\left(5\right)$

$i_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">p</figure-callout>}2}=\frac{r_1{I}_o}{K({\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+r_2)}-\frac{2\mathrm{\&Delta;}{U}_o}{{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+r_2}----\left(6\right)$

i _P1＞i _P2, the dividing potential drop capacitor C _I1Discharge, capacitor C _I2Charging.Along with the recovery of midpoint potential, undulate quantity Δ U _oCan reduce primary current i _P1, i _P2Also can change.After undulate quantity is eliminated, primary current i _P1, i _P2Also can revert to I _o/ 2K.In order to simplify calculating, the mean value that we get both calculates:

$I_{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">p</figure-callout>}1}=\frac{{\mathrm{<figure-callout\; id="1"\; label="i\; p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">i</figure-callout>}}_p+\frac{I_o}{2\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">K</figure-callout>}}}{2}=\frac{r_2{I}_o}{2K({\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+r_2)}+\frac{\mathrm{\&Delta;}{U}_o}{{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_2}+\frac{I_o}{4K}----\left(7\right)$

$I_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">p</figure-callout>}2}=\frac{{\mathrm{<figure-callout\; id="2"\; label="i\; p"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">i</figure-callout>}}_p+\frac{I_o}{2\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">K</figure-callout>}}}{2}=\frac{r_1{I}_o}{2K({\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+r_2)}+\frac{\mathrm{\&Delta;}{U}_o}{{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_2}+\frac{I_o}{4K}----\left(8\right)$

The unbalanced reverse fluctuation that causes of primary current (the fluctuation Δ U that causes with disturbance _oPhase place is opposite) be Δ U _o', establish elapsed time t _rMidpoint potential returns to 1/2nd input voltages, and Δ U at this moment fluctuates _o' just in time offset disturbance Δ U _o

$\mathrm{\&Delta;}{U}_o=\frac{I_{p1}}{C_{i1}}*t_r\frac{I_{p2}}{C_{i2}}*t_r=\frac{(r_2-r_1)I_o}{2C_{\mathrm{is}}K({\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+r_2)}*t_r+\frac{2\mathrm{\&Delta;}{U}_o}{C_{\mathrm{is}}({\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+r_2)}*t_r$

ΔU _o＝ΔU _o

: $t_r=\frac{2K{C}_{\mathrm{is}}\mathrm{\&Delta;}{U}_o({\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20041001395400093.png,A20041001395400112.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+r_2)}{4\mathrm{K\&Delta;}{U}_o+(r_2-r_1)I_o}----\left(9\right)$

By formula (9) as can be seen, is is big more for input dividing potential drop capacitor C, and midpoint potential is not easy more by disturbance, and after the disturbance, recovery time is long more; Is is more little for input dividing potential drop capacitor C, and midpoint potential is easy of more disturbance, and after the disturbance, recovery time is short more.So after dividing potential drop electric capacity midpoint potential is disturbed, can recover automatically by transformer clamping, promptly importing dividing potential drop electric capacity can automatically equalizing voltage.

In sum, the transformer clamping ZVS three level full-bridge converters that this paper proposed and expanded circuit thereof have successfully solved the difficult problem of high input voltage, big through-put power.The switching tube chopper circuit 3 that the key of technology is dividing potential drop electric capacity 2 among Fig. 3, be made up of the bridge of enjoying a double blessing combines with isolating transformer 4 former limit windings; therefore; this three part is the core of technical patent application in conjunction with the circuit topology and the utilization of transformer clamping technical know-how in this circuit that constitute, requires to be subjected to patent protection.

Claims (2)

1. transformer clamping no-voltage three level full-bridge converters comprise that the output of direct voltage input (1) is connected in the input of dividing potential drop electric capacity (2) and switching tube chopper circuit (3), the output of switching tube chopper circuit (3) is connected in the input of transformer isolation circuit (4), its output is connected in dc voltage output circuit (6) behind current rectifying and wave filtering circuit (5), it is characterized in that described switching tube chopper circuit (3) is by four switching tube (Q of the 1st, the 3rd, the 5th and the 7th ₁, Q ₃, Q ₅, Q ₇) successively the positive and negative two ends after the forward series connection be connected in parallel on two dividing potential drop input capacitance (C _I1) and (C _I2) the series circuit two ends, and the 3rd switching tube (Q ₃) and the 5th switching tube (Q ₅) series connection mid point and two dividing potential drop input capacitance (C _I1) and (C _I2) the series connection mid point be connected to form the leading-bridge of full-bridge circuit; 2nd, four switching tube (Q in addition of the 4th, the 6th and the 8th ₂, Q ₄, Q ₆, Q ₈) successively the positive and negative two ends after the forward series connection be connected in parallel on two dividing potential drop input capacitance (C equally _I1) and (C _I2) the series circuit two ends, the 4th switching tube (Q ₄) and the 6th switching tube (Q ₆) series connection mid point and two dividing potential drop input capacitance (C _I1) and (C _I2) the series connection mid point be connected to form the lagging leg of full-bridge circuit, two the winding (N in the former limit of the transformer of described transformer isolation circuit (4) _P1) and (N _P2) on the same magnetic core of transformer, the number of turn of two windings is identical, one of them winding (N _P1) same inscription end be connected in leading-bridge the 1st switching tube (Q ₁) and the 3rd switching tube (Q ₃) the series connection mid point, different inscription end is connected in lagging leg the 2nd switching tube (Q ₂) and the 4th switching tube (Q ₄) the series connection mid point, another winding (N _P2) same inscription end be connected in leading-bridge the 5th switching tube (Q ₅) and the 7th switching tube (Q ₇) the series connection mid point, different inscription end is connected in lagging leg the 6th switching tube (Q ₆) and the 8th switching tube (Q ₈) the series connection mid point, constitute transformer clamping thus.

2. the transformer clamping according to claim 1 three level full-bridge converters that compress switch zero point is characterized in that the expanded circuit of transformer is on the basis of three level full-bridge converters, the dividing potential drop of connecting again electric capacity (C _In), each dividing potential drop electric capacity (C _In) two ends connect one and be connected in an all identical former limit winding (N of its number of turn on the corresponding transformer that is wound on same transformer isolation circuit (4) again by the connect output of the full-bridge circuit (FB-n) formed and each full-bridge circuit (FB-n) of two switching tubes of two switching tubes series connection and other _Pn), n=3 wherein, 4,5,6.......

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