CN201563061U - Lifting voltage type soft switch direct current converter - Google Patents

Abstract

The utility model relates to a lifting voltage type soft switch direct current converter which comprises a main switching tube Q, a fly-wheel diode D1, an inductor L0, resonance capacitors Cr1 and Cr2, an auxiliary switching tube Q1, a resonance inductor Lr, diodes D1, D2 and D3, a filtering capacitor C0 and a resistor R0. The converter is characterized in that one end of the resonance capacitor Cr2, the negative electrode of the diode D2 and the collector electrode of the main switching tube Q are connected with the positive electrode of a power supply; the other end of the resonance capacitor Cr2 is connected with the positive electrode of the diode D2, the negative electrode of the diode D3 and one end of the resonance capacitor Lr; the other end of the resonance inductor Lr is connected with one end of the resonance capacitor Cr1; and the other end of the resonance capacitor Cr1 is connected with the negative electrode of the diode D1 and the collector electrode of the auxiliary switching tube Q1. The utility model realizes the soft switching of the main and auxiliary switching tubes by adopting an auxiliary resonance network, the main switching tube realizes zero current and zero voltage cut off, and the auxiliary switching tube realizes zero current conduction and close. The utility model has the advantages of voltage lifting, small switching consumption, high efficiency and the like, and can be used for occasions of high voltage, large power and the like.

Description

The soft switch DC converter of a kind of buck-boost type

Technical field

The utility model relates to the soft switch DC converter of a kind of buck-boost type.

Background technology

In recent years, the expansion of switching device kind, performance parameters improves.Power MOSFET is the first-selection in low-voltage, the frequency applications, and in high voltage, medium-high frequency converter, the superiority of IGBT becomes increasingly conspicuous, and becomes the main flow device.But in high voltage, high-power applications occasion, voltage, current stress that power device bears are big, switching loss is big, and particularly the hangover electric current that forms in turn off process of IGBT produces bigger turn-off power loss with the collector voltage that raises, and switching frequency is difficult to improve.Adopting soft switch technique (especially zero-current switching) is the effective ways that overcome IGBT frequency applications obstacle.

Soft switch technique has experienced the evolution of resonant type soft-switch technology, zero switching technique and branch on zero technology, wherein the branch on zero converter is owing to adopt the resonant process of auxiliary resonant net control resonant element, when keeping the pwm converter advantage, realized soft switch, having reduced switching loss, is the research focus of present field of power electronics.But because auxiliary network has also been introduced the switching loss of auxiliary tube accordingly, if auxiliary tube is operated in the hard switching state, the switching loss of generation is also influential to the efficient of whole converter, if the auxiliary tube MOSFET of high pressure, then device cost is very high.Also adopt IGBT as auxiliary tube, be responsible for IGBT high voltage, high-power output requirement to adapt to, then auxiliary tube soft commutation break-make is also very important, and the effect of soft switch can also improve the functional reliability of switching device except reducing switching loss.Consider that from the reliability angle auxiliary tube also should adopt soft switch technique.

Summary of the invention

The purpose of this utility model provides the soft switch DC converter of a kind of buck-boost type, and it adopts auxiliary resonant net to realize the soft switch of main and auxiliary switching tube, is responsible for to the zero current no-voltage and turn-offs, and auxiliary tube has been realized the zero current break-make.

The utility model is achieved in that the soft switch DC converter of a kind of buck-boost type, comprises main switch Q, sustained diode ₀, inductance L ₀, resonant capacitance C _R1, C _R2, auxiliary switch Q ₁, resonant inductance L _r, diode D ₁, D ₂, D ₃, filter capacitor C ₀And resistance R ₀, it is characterized in that: described resonant capacitance C _R2An end, diode D ₂Negative pole and the collector electrode of main switch Q be connected with positive source; Described resonant capacitance C _R2The other end and diode D ₂Positive pole, diode D ₃Negative pole, resonant inductance L _rAn end be connected; Described resonant inductance L _rThe other end and resonant capacitance C _R1An end be connected; Described resonant capacitance C _R1The other end and diode D ₁Negative pole, auxiliary switch Q ₁Collector electrode be connected; Described diode D ₁Positive pole and emitter-base bandgap grading, the auxiliary switch Q of main switch Q ₁Emitter-base bandgap grading, sustained diode ₀Negative pole, inductance L ₀An end be connected; Described sustained diode ₀Positive pole and diode D ₃Positive pole, filter capacitor C ₀An end and resistance R ₀An end be connected; Described inductance L ₀The other end, filter capacitor C ₀The other end, resistance R ₀The other end be connected with the negative pole of power supply.

The utlity model has that liftable is pressed, switching loss is little, efficient is high, can be applicable to high voltage, occasion such as high-power.

Description of drawings

Fig. 1 is the circuit diagram of the utility model embodiment.

Fig. 2 is the utility model groundwork waveform schematic diagram.

Fig. 3 a ~ Fig. 3 f is the utility model t ₀～t ₆Each time period operation principle schematic circuit diagram.

Embodiment

Below in conjunction with drawings and Examples the utility model is described further.

As shown in Figure 1, the utility model provides a kind of buck-boost type soft switch DC converter, comprises main switch Q, sustained diode ₀, inductance L ₀, resonant capacitance C _R1, C _R2, auxiliary switch Q ₁, resonant inductance L _r, diode D ₁, D ₂, D ₃, filter capacitor C ₀And resistance R ₀, it is characterized in that: described resonant capacitance C _R2An end, diode D ₂Negative pole and the collector electrode of main switch Q be connected with positive source; Described resonant capacitance C _R2The other end and diode D ₂Positive pole, diode D ₃Negative pole, resonant inductance L _rAn end be connected; Described resonant inductance L _rThe other end and resonant capacitance C _R1An end be connected; Described resonant capacitance C _R1The other end and diode D ₁Negative pole, auxiliary switch Q ₁Collector electrode be connected; Described diode D ₁Positive pole and emitter-base bandgap grading, the auxiliary switch Q of main switch Q ₁Emitter-base bandgap grading, sustained diode ₀Negative pole, inductance L ₀An end be connected; Described sustained diode ₀Positive pole and diode D ₃Positive pole, filter capacitor C ₀An end and resistance R ₀An end be connected; Described inductance L ₀The other end, filter capacitor C ₀The other end, resistance R ₀The other end be connected with the negative pole of power supply.

In order to make those skilled in the art fully understand the utility model, cooperate Fig. 2 and Fig. 3 a～Fig. 3 f to be described further below, here to simplify the analysis, we do following hypothesis:

(1) all components and parts all are desirable in the circuit,

(2) filter inductance L ₀Enough is big; In a switch periods, its electric current remains unchanged substantially, the constant-current source that can to regard an electric current as be Io.

(3) t=t ₁Before, resonant capacitance C _R1Voltage be-V _Cr1max, resonant capacitance C _R2Voltage be zero.Six kinds of operational modes are arranged in the switch periods.

(a) pattern 1 (t ₀～t ₁)

The main switch conducting, auxiliary switch turn-offs, and circuit working is at traditional PWM state (shown in Fig. 3 a).

(b) pattern 2 (t ₁～t ₂)

t ₁The time auxiliary tube conducting, L _rWith C _R1And C _R2Resonance takes place, shown in Fig. 3 b.Inductive current i _LrStarting from scratch increases gradually, with it Chuan Lian auxiliary tube zero current turning-on.The main switch current i _c=I _O-i _LrReduce process gradually

Behind the harmonic period, the main switch electric current drops to zero, and turn-off main switch Q this moment, realized the zero-current switching of main switch.

(c) mode 3 (t ₂～t ₃)

t ₂The time main switch Q turn-off, be responsible for both end voltage V _Ce, V _Cr1And V _Cr2Raise gradually.Work as V _Ce=V _In+ V _CThe time sustained diode ₀V is worked as in conducting _Cr2=V _In+ V _CThe time, D ₃Conducting, the resonance branch road is transferred to L _r, C _R1Continue resonance, shown in Fig. 3 c.The resonant inductance electric current reduces gradually, when the resonant inductance current i _LrWhen being zero, D ₃End, this resonance branch road stops resonance, capacitor C _R1Both end voltage reaches maximum.

(d) pattern 4 (t ₃～t ₄)

t ₃The time i _Lr=0, Chuan Lian auxiliary switch Q with it ₁Electric current also is zero, t ₃Turn-off auxiliary switch later on and can realize auxiliary tube Q ₁Zero-current switching.After this circuit working is the inductance afterflow stage, as Fig. 3 d at traditional PWM state.

(e) pattern 5 (t ₄～t ₅)

t ₄The time be responsible for conducting, this stage circuit is again the resonant energy reseting procedure both to inductance linear-charging simultaneously.Resonant element energy reseting period, L _rElder generation and C _R1And C _R2Resonance takes place, C _R1And C _R2Voltage reduces gradually, as Fig. 3 e.

(f) pattern 6 (t ₅～t ₆)

Work as C _R2When voltage is reduced to zero, D ₂Conducting, L _rContinue and C _R1Resonance is shown in Fig. 3 f, up to i _LrStopped resonance at=0 o'clock.Capacitor C _R1Voltage reaches negative maximum.t ₆After, circuit is got back to traditional PWM operating state again, repeats a switch periods.

From above-mentioned soft switch analysis as can be seen, realize the zero-current switching be responsible for, make V before need in pattern 2, being responsible for conducting _Cr1max＜0, and must meet the following conditions:

$\left|\frac{V_{\mathrm{crl}\max }}{Z}\right|\≥I_0$ (1)

In the formula, $Z=\sqrt{\frac{L_r({\mathrm{<figure-callout\; id="1"\; label="C\; r"\; filenames="H200920314103X20091105E000012.png,H200920314103X20091105E000032.png"\; state="\{\{state\}\}">C</figure-callout>}}_r+C_{r2})}{C_{r1}{\mathrm{<figure-callout\; id="2"\; label="C\; r"\; filenames="H200920314103X20091105E000011.png"\; state="\{\{state\}\}">C</figure-callout>}}_r}}.$

In order to make C in the mode 3 _R2Charging rate enough fast, in the short as far as possible time, finish the conversion of mode 3 to pattern 4, this just requires capacitor C _R2Get as far as possible littler, simultaneously by at C _R2Two ends D in parallel ₂, C _R2The reverse voltage clamper can make C to zero _R2Be charged to V as early as possible _InMake D ₃Conducting

In order to satisfy $\left|\frac{V_{\mathrm{crl}\max }}{Z}\right|\&GreaterEqual;{\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="H200920314103X20091105E000023.png,H200920314103X20091105E000024.png"\; state="\{\{state\}\}">I</figure-callout>}}_0$ With the harmonic period that reduces pattern 4, finish the conversion of pattern 4 as early as possible, C to pattern 5 _R1Also should get as far as possible littler, but too little C _R1And C _R2Make in the pattern 2 current transfer too fast, realize that to being responsible for zero-current soft switch is unfavorable.So C _R1And C _R2Should trade off and select, occurrence is adjusted by side circuit.

Analyze as can be seen from pattern 2, in 1/4th harmonic periods after the auxiliary tube conducting, the resonant inductance electric current reaches maximum, and this moment, the main switch electric current was transferred to the resonance branch road fully, realizes that zero-current switching should satisfy so be responsible for:

$\frac{\mathrm{\&pi;}}{2}\sqrt{\frac{L_r{C}_{r1}{C}_{r2}}{{\mathrm{<figure-callout\; id="1"\; label="C\; r"\; filenames="H200920314103X20091105E000012.png,H200920314103X20091105E000032.png"\; state="\{\{state\}\}">C</figure-callout>}}_r+{\mathrm{<figure-callout\; id="2"\; label="C\; r"\; filenames="H200920314103X20091105E000011.png"\; state="\{\{state\}\}">C</figure-callout>}}_r}}\&GreaterEqual;t_{01}---\left(2\right)$

Then have

$L_r=\frac{{4\mathrm{<figure-callout\; id="01"\; label="f"\; filenames="H200920314103X20091105E000012.png"\; state="\{\{state\}\}">f</figure-callout>}}_{01}^2({\mathrm{<figure-callout\; id="1"\; label="C\; r"\; filenames="H200920314103X20091105E000012.png,H200920314103X20091105E000032.png"\; state="\{\{state\}\}">C</figure-callout>}}_r+C_{r2})}{{\mathrm{\&pi;}}^2{C}_{r1}{C}_{r2}}---\left(3\right)$

T in the formula ₀₁Desirable 0.03T (T is a switch periods).

The above only is preferred embodiment of the present utility model, and all equalizations of being done according to the utility model claim change and modify, and all should belong to covering scope of the present utility model.

Claims (1)

1. the soft switch DC converter of buck-boost type comprises main switch (Q), fly-wheel diode (D ₀), inductance (L ₀), resonant capacitance (C _R1, C _R2), auxiliary switch (Q ₁), resonant inductance (L _r), diode (D ₁, D ₂, D ₃), filter capacitor (C ₀) and resistance (R ₀), it is characterized in that: described resonant capacitance (C _R2) an end, diode D ₂Negative pole and the collector electrode of main switch (Q) be connected with positive source; Described resonant capacitance (C _R2) the other end and diode (D ₂) positive pole, diode (D ₃) negative pole, resonant inductance (L _r) an end be connected; Described resonant inductance (L _r) the other end and resonant capacitance (C _R1) an end be connected; Described resonant capacitance (C _R1) the other end and diode (D ₁) negative pole, auxiliary switch (Q ₁) collector electrode be connected; Described diode (D ₁) positive pole and emitter-base bandgap grading, the auxiliary switch (Q of main switch (Q) ₁) emitter-base bandgap grading, fly-wheel diode (D ₀) negative pole, inductance (L ₀) an end be connected; Described fly-wheel diode (D ₀) positive pole and diode (D ₃) positive pole, filter capacitor (C ₀) an end and resistance (R ₀) an end be connected; Described inductance (L ₀) the other end, filter capacitor (C ₀) the other end, resistance (R ₀) the other end be connected with the negative pole of power supply.

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