CN203434858U - Novel double-input buck-boost DC-DC converter - Google Patents

Abstract

The utility model discloses a circuit topology of a novel double-input buck-boost DC-DC converter and belongs to the technical field of power electronics. The converter is structurally derived from a traditional three-level Buck-Boost DC-DC converter and structurally comprises two direct-current input sources Vin1 and Vin2, two switching tubes Q1 and Q2, two boost inductors Lf1 and Lf2, two freewheel diodes VD1 and VD2, two output voltage-dividing capacitors Cf1 and Cf2 and a load resistor RLd, wherein, Q1 and Q2 can be driven simultaneously and can be driven in a staggered mode by a certain angle; the two output voltage-dividing capacitors Cf1 and Cf2 are high and equal in capacity; amplitude values and characteristics of the two input sources Vin1 and Vin2 can be either the same or different. The double-input buck-boost DC-DC converter disclosed by the utility model can work either in a single-input state or in a double-input state, and stability and flexibility of a distributed power generation system can be improved. In addition, the double-input buck-boost DC-DC converter has the advantages of simple circuit structure, small system size and low cost.

Description

A kind of novel dual input step-down/up type DC-DC converter

Technical field

The utility model relates to a kind of novel dual input step-down/up type DC-DC converter circuit topology, belongs to electronic power converter technical field.

Background technology

Day by day serious along with world energy sources crisis and environmental pollution, solar electric power supply system is more and more extensive in China's application.Yet as electric power system independently, because being easily subject to the impact of environment, there is unstable, the discontinuous shortcoming of supply of electric power in solar energy.Wind energy is formed to associating electric power system with solar energy, can greatly reduce the unsettled shortcoming of supply of electric power, improve the stability of a system.

In traditional scene associating electric power system two kinds of energy forms each need a DC converter, be connected in parallel on public DC bus after wind energy and solar energy are become to direct current output, complex structure, cost is high, system effectiveness is low.For simplied system structure, reduce costs, can replace two single input direct-current converters with Double-input direct-current converter.

At present, the domestic and international Research Literature for Double-input direct-current converter has a lot.According to the operation mode of input source, Double-input direct-current converter is mainly divided into two classes.One class belongs to time sharing mode electric power-feeding structure, and this structural circuit is simple in structure, and two input sources all belong to parallel-connection structure, is easily expanded into the situation of a plurality of inputs, but can only have at any one time the independent powering load of a kind of input source.The another kind of electric power-feeding structure simultaneously that belongs to, in a switch periods, two input sources can provide energy to load simultaneously, also can to load, provide energy separately by an input source, realized the comprehensive utilization of the energy, but studying at present more is dual input Buck converter topology and dual input Boost converter topology, these two kinds of converters are merely able to independent step-down and the boost function realized, and voltage gain is lower, all can not meet well the requirement of system flexibility and stability.

Summary of the invention

For the problems referred to above, the utility model provides a kind of new dual input step-down/up type DC-DC converter circuit topological structure, and it is derived and come by traditional Buck-Boost three-level DC converter.

The technical solution adopted in the utility model is as follows:

A dual input step-down/up type DC-DC converter, comprises two direct current input sources, two switching tubes, two intermediate energy storage inductance, two fly-wheel diodes, two output dividing potential drop electric capacity and a load resistance R _ld, wherein, two direct current input sources are connected in series, direct current input source V _in1positive pole meet switching tube Q ₁drain electrode, switching tube Q ₁source electrode meet fly-wheel diode VD ₁negative electrode, fly-wheel diode VD ₁anode meet load resistance R _ldone end, load resistance R _ldthe other end and fly-wheel diode VD ₂negative electrode be connected, fly-wheel diode VD ₂anode meet switching tube Q ₂drain electrode, switching tube Q ₂source electrode meet direct current input source V _in2negative pole;

Two output dividing potential drop capacitances in series connect rear and load resistance R _ldparallel connection, output dividing potential drop capacitor C _f1negative pole meet fly-wheel diode VD ₁anode, output dividing potential drop capacitor C _f2positive pole meet fly-wheel diode VD ₂negative electrode;

Two intermediate energy storage inductance are connected in series, intermediate energy storage inductance L _f1positive pole connect fly-wheel diode VD ₁negative electrode, intermediate energy storage inductance L _f2negative pole connect fly-wheel diode VD ₂anode; Output dividing potential drop capacitor C _f1positive pole and intermediate energy storage inductance L _f1negative pole be connected, intermediate energy storage inductance L _f1negative pole and direct-current input power supplying V _in2positive pole be connected.

The amplitude of two direct current input sources and characteristic can be identical, also can difference very large; Direct current input source V _in1and V _in2can power to the load at the same time or separately.Switching tube Q ₁and Q ₂can drive the certain angle work of also can staggering simultaneously.

The utility model allows two kinds of energy inputs, the amplitude of input source and characteristic can be identical, also can difference very large, two kinds of input sources can power to the load respectively or simultaneously, output voltage range is wide, voltage gain is large, therefore the stability and the flexibility that have improved system, realized the comprehensive utilization of the energy.In addition, the utility model, for the distributed generation system with two single input direct-current converters, has advantages of that circuit structure is simple, system bulk is little, cost is low.

Accompanying drawing explanation

Fig. 1 is dual input step-down/up type DC-DC converter circuit topology theory figure of the present utility model.

Fig. 2 is the equivalent electric circuit of the different switch mode of dual input step-down/up type DC-DC converter of the present utility model, wherein: (a) Q ₁and Q ₂conducting simultaneously; (b) Q ₁conducting, Q ₂turn-off; (c) Q ₁turn-off Q ₂conducting; (d) Q ₁and Q ₂turn-off simultaneously; (e) inductive current equals zero.

Fig. 3 is dual input step-down/up type DC-DC converter circuit topology steady operation waveform of the present utility model, wherein: (a) Q ₁and Q ₂the steady operation waveform simultaneously driving; (b) Q ₁and Q ₂differ the steady operation waveform of 180 ° of drivings.

Fig. 4 is the oscillogram of the static Simulation experiment of the utility model two-way input source while simultaneously working, wherein: (a) Q ₁and Q ₂the static Simulation waveform simultaneously driving; (b) Q ₁and Q ₂differ the static Simulation waveform of 180 ° of drivings.

Fig. 5 is the oscillogram of the static Simulation experiment of the utility model one road input source while working independently, wherein: (a) V _in1static Simulation waveform while working independently; (b) V _in2static Simulation waveform while working independently.

Fig. 6 is the oscillogram of the utility model two-way input source emulation experiment that input source changes while working simultaneously, wherein: (a) V _in1=60V, V _in2=140V; (b) V _in1=80V, V _in2=140V.

Fig. 7 is the oscillogram of the utility model two-way input source emulation experiment of load variations while simultaneously working, wherein: (a) R _ld=50 Ω; (b) R _ld=100 Ω.

Fig. 8 is the oscillogram of the utility model two-way input source emulation experiment of change in duty cycle while simultaneously working, wherein: (a) D ₁=0.4, D ₂=0.3; (b) D ₁=0.6, D ₂=0.3.

Embodiment

Below in conjunction with accompanying drawing, the utility model is made and being further illustrated.

Accompanying drawing 1 is dual input step-down/up type DC-DC converter circuit figure of the present utility model.

Dual input step-down/up type DC-DC converter, comprises 2 direct current input source V _in1and V _in2, 2 switching tube Q ₁and Q ₂, 2 intermediate energy storage inductance L _f1and L _f2, 2 fly-wheel diode VD ₁and VD ₂, 2 output dividing potential drop capacitor C _f1and C _f2and 1 load resistance R _ld.Wherein, 2 direct current input source V _in1and V _in2be connected in series V _in1positive pole meet switching tube Q ₁drain electrode, switching tube Q ₁source electrode meet fly-wheel diode VD ₁negative electrode, fly-wheel diode VD ₁anode meet load resistance R _ldone end, load resistance R _ldthe other end and fly-wheel diode VD ₂negative electrode be connected, fly-wheel diode VD ₂anode meet switching tube Q ₂drain electrode, switching tube Q ₂source electrode meet direct current input source V _in2negative pole; 2 output dividing potential drop capacitor C _f1and C _f2be connected in series rear and load resistance R _ldparallel connection, output dividing potential drop capacitor C _f1negative pole meet fly-wheel diode VD ₁anode, output dividing potential drop capacitor C _f2anode meet fly-wheel diode VD ₂negative electrode; Two intermediate energy storage inductance L _f1and L _f2be connected in series intermediate energy storage inductance L _f1positive pole connect fly-wheel diode VD ₁negative electrode, intermediate energy storage inductance L _f2negative pole connect fly-wheel diode VD ₂anode; Output dividing potential drop capacitor C _f1positive pole and intermediate energy storage inductance L _f1negative pole be connected, intermediate energy storage inductance L _f1negative pole and direct-current input power supplying V _in2positive pole be connected.

With reference to the accompanying drawings 1 concrete analysis circuit operation mode.V wherein _in1, V _in2be respectively two-way DC input voitage, V _oand I _obe respectively output voltage and output current, Q ₁, Q ₂be two switching tubes, VD ₁, VD ₂for fly-wheel diode, L _f1and L _f2intermediate energy storage inductance, C _f1and C _f2be two output dividing potential drop electric capacity, its capacity is very large and equate R _ldit is load resistance.Q ₁, Q ₂can be simultaneously open-minded, the certain angle work of also can staggering.It is example that the utility model be take the situation that same switch frequency, two switching tubes drive simultaneously, introduces its operation principle.According to the on off state of two switching tubes, there are following 5 kinds of switch mode in converter.Accompanying drawing 2 has provided the equivalent electric circuit of the different switch mode of dual input step-down/up type DC-DC converter of the present utility model.

(1) switch mode I.As shown in Fig. 2 (a), switching tube Q ₁and Q ₂conducting simultaneously, fly-wheel diode VD ₁and VD ₂all turn-off VD ₁and VD ₂the voltage stress bearing is respectively V _in1+ V _cf1and V _in2+ V _cf2.Direct-current input power supplying V _in1and V _in2respectively to middle energy storage inductor L _f1and L _f2charging, inductance L _f1and L _f2linear increase of electric current, output dividing potential drop capacitor C _f1and C _f2both connect jointly to load R _ldpower supply.Now, inductance L _f1both end voltage V _lf1=V _in1, inductance L _f2both end voltage V _lf2=V _in2.

(2) switch mode II.As shown in Fig. 2 (b), switching tube Q ₁conducting, Q ₂turn-off fly-wheel diode VD ₁shutoff, VD ₂conducting, direct-current input power supplying V _in1to middle energy storage inductor L _f1charging, inductance L _f1linear the increasing of electric current, output dividing potential drop capacitor C _f1electric discharge, intermediate energy storage inductance L _f2by fly-wheel diode VD ₂to capacitor C _f2with load resistance R _ldpower supply, inductance L _f2electric current linearity reduce.Now, inductance L _f1both end voltage V _lf1=V _in1, inductance L _f2both end voltage V _lf2=-V _cf2.

(3) switch mode III.As shown in Fig. 2 (c), switching tube Q ₁shutoff, Q ₂conducting, fly-wheel diode VD ₁conducting, VD ₂turn-off direct-current input power supplying V _in2to inductance L _f2charging, inductance L _f2linear the increasing of electric current, output dividing potential drop capacitor C _f2electric discharge, inductance L _f1by fly-wheel diode VD ₁to capacitor C _f1with load resistance R _ldpower supply, inductance L _f1electric current linearity reduce.Inductance L now _f1both end voltage V _lf1=-V _cf1, inductance L _f2both end voltage V _lf2=V _in2.

(4) switch mode IV.As shown in Fig. 2 (d), switching tube Q ₁and Q ₂turn-off fly-wheel diode VD simultaneously ₁and VD ₂all conductings, intermediate energy storage inductance L _f1and L _f2by fly-wheel diode VD ₁and VD ₂to dividing potential drop capacitor C _f1, C _f2with load resistance R _ldpower supply, inductance L _f1and L _f2electric current linearity reduce.Inductance L now _f1both end voltage V _lf1=-V _cf1, inductance L _f2both end voltage V _lf2=-V _cf2.

(5) switch mode V.As shown in Fig. 2 (e), as middle energy storage inductor L _f1and L _f2during less the or load reduction of inductance value, inductive current will be zero, and load is powered by output filter capacitor.

From above-mentioned each operational modal analysis, V _in1while powering to the load separately, mode II and mode IV alternation, fly-wheel diode VD ₂all the time conducting, inductive current i during stable state _lf2all the time equal output current, therefore V _lf2==0, so capacitor C _f2by diode VD ₂all the time be clamped at-0.7V left and right (being 0V under perfect condition), this converter is equivalent to a traditional B uck-Boost DC-DC converter.V _in2while powering to the load separately, principle is similar.When two-way input source is worked simultaneously, this converter is equivalent to the output series connection of two traditional B uck-Boost DC-DC converters.Switching tube Q ₁with fly-wheel diode VD ₁the voltage stress bearing is V _in1+ V _cf1, switching tube Q ₂with fly-wheel diode VD ₂the voltage stress bearing is V _in2+ V _cf2, with respect to traditional Buck-Boost DC-DC converter, reduced the voltage stress of switching device.Therefore during practical application, this converter topology preferably functions in dual input state, is conducive to like this reduce the voltage stress of switching device, reduces the ON time of fly-wheel diode.

Accompanying drawing 3 has provided V _in1<V _o, V _in2<V _oconverter steady operation waveform, v wherein _gS1and v _gS2be respectively switching tube Q ₁and Q ₂drive signal.Suppose duty ratio D ₁<D ₂, wherein Fig. 3 (a) is that two switching tubes drive simultaneously, at a switch periods T _sin, circuit working sequential is respectively mode I, III and mode IV.Fig. 3 (b) is that two switching tubes differ 180 ° of drivings, at a switch periods T _sin, circuit working sequential is respectively mode I, II, IV and mode III.

With reference to the accompanying drawings 3, to inductance L _f1and L _f2the weber equilibrium principle of applying respectively inductance, can obtain:

V _in1D ₁T _s-V _Cf1(1-D ₁)T _s=0 (1)

V _in2D ₂T _s-V _Cf2(1-D ₂)T _s=0 (2)

By formula (1) and formula (2), can obtain stable state I/O relation:

$V_o=V_{\mathrm{<figure-callout\; id="1"\; label="Cf"\; filenames="HDA00003375602800012.png,HDA00003375602800031.png"\; state="\{\{state\}\}">Cf</figure-callout>}1}+{\mathrm{<figure-callout\; id="2"\; label="V\; Cf"\; filenames="HDA00003375602800031.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{Cf}}=\frac{{\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HDA00003375602800012.png,HDA00003375602800031.png"\; state="\{\{state\}\}">D</figure-callout>}}_1}{1-D_1}{V}_{\mathrm{in}1}+\frac{{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00003375602800031.png"\; state="\{\{state\}\}">D</figure-callout>}}_2}{1-D_2}{V}_{\mathrm{in}2}---\left(3\right)$

To capacitor C _f1and C _f2apply respectively electric capacity ampere-second equilibrium principle, can obtain:

$I_{\mathrm{<figure-callout\; id="1"\; label="Lf"\; filenames="HDA00003375602800012.png,HDA00003375602800031.png"\; state="\{\{state\}\}">Lf</figure-callout>}1}=\frac{I_o}{1-D_1}---\left(4\right)$

$I_{\mathrm{<figure-callout\; id="2"\; label="Lf"\; filenames="HDA00003375602800031.png"\; state="\{\{state\}\}">Lf</figure-callout>}2}=\frac{I_o}{1-D_2}---\left(5\right)$

So the mean value of two input source input currents is respectively:

$I_{\mathrm{in}1}=D_1{\mathrm{<figure-callout\; id="1"\; label="I\; Lf"\; filenames="HDA00003375602800012.png,HDA00003375602800031.png"\; state="\{\{state\}\}">I</figure-callout>}}_{\mathrm{Lf}}=\frac{D_1{I}_o}{1-D_1}---\left(6\right)$

$I_{\mathrm{in}2}=D_2{\mathrm{<figure-callout\; id="2"\; label="I\; Lf"\; filenames="HDA00003375602800031.png"\; state="\{\{state\}\}">I</figure-callout>}}_{\mathrm{Lf}}=\frac{D_2{I}_o}{1-D_2}---\left(7\right)$

In formula, I _lf1, I _lf2be respectively inductance L _f1, L _f2stable state average current.

Accompanying drawing 4-8 is the oscillogram that the utility model carries out emulation experiment.

Wherein, the static Simulation waveform that accompanying drawing 4 is worked for two-way input source simultaneously, Fig. 4 (a) is the situation that two switching tubes drive simultaneously, Fig. 4 (b) is the situation of the staggered 180 ° of drivings of two switching tubes.As can be seen from Figure 4: no matter two switching tubes are to drive or staggered 180 ° of drivings simultaneously, switching tube Q ₁during conducting, inductance L _f1linear increase of electric current, capacitor C _f1electric discharge; As switching tube Q ₁during shutoff, inductance L _f1electric current linearity reduce, capacitor C _f1charging.Switching tube Q ₂during conducting, inductance L _f2linear increase of electric current, capacitor C _f2electric discharge; As switching tube Q ₂during shutoff, inductance L _f2electric current linearity reduce, capacitor C _f2charging.

The static Simulation waveform that accompanying drawing 5 Wei Yi road input sources work independently, Fig. 5 (a) V _in1static Simulation waveform while working independently, Fig. 5 (b) V _in2static Simulation waveform while working independently.From Fig. 5 (a), can find out: V _in1while powering to the load separately, switching tube Q ₁during conducting, inductance L _f1linear increase of electric current, capacitor C _f1electric discharge; As switching tube Q ₁during shutoff, inductance L _f1electric current linearity reduce, capacitor C _f1charging.Capacitor C _f2all be clamped in whole switch periods-0.7V left and right (being 0V under perfect condition).From Fig. 5 (b), can find out: V _in2while powering to the load separately, switching tube Q ₂during conducting, inductance L _f2linear increase of electric current, capacitor C _f2electric discharge; As switching tube Q ₂during shutoff, inductance L _f2electric current linearity reduce, capacitor C _f2charging.Capacitor C _f1all be clamped in whole switch periods-0.7V left and right (being 0V under perfect condition).

As can be seen from Figure 4 and Figure 5, dual input Buck-Boost DC-DC converter two drives signal both can drive the 180 ° of drivings that also can interlock simultaneously; Both allow two-way input source to power to the load simultaneously, and allowed again a road input source to power to the load separately.Simulation results show the correctness of dual input Buck-Boost DC-DC converter principle Analysis.

When accompanying drawing 6 has provided input source variation, the simulation waveform of two capacitance voltages and output voltage.Fig. 6 (a) is V _in1=60V, V _in2=140V, D ₁=0.4, D ₂the simulation waveform of=0.3 o'clock, as can be seen from the figure V _cf1=40V, V _cf2=60V, V _o=100V.Fig. 6 (b) is V _in1=80V, V _in2=140V, D ₁=0.4, D ₂the simulation waveform of=0.3 o'clock, as can be seen from the figure V _cf1=53V, V _cf2=60V, V _o=113V.All meet formula (3).

When accompanying drawing 7 has provided load variations, the simulation waveform of two capacitance voltages and output voltage.Fig. 7 (a) is V _in1=60V, V _in2=140V, D ₁=0.4, D ₂=0.3, R _ldsimulation waveform during=50 Ω, Fig. 7 (b) is V _in1=60V, V _in2=140V, D ₁=0.4, D ₂=0.3, R _ldsimulation waveform during=100 Ω.As can be seen from Figure 7 dual input Buck-Boost DC-DC converter two capacitance voltage values and output voltage values all remain unchanged, and meet formula (3).

Accompanying drawing 8 has provided input voltage and load is constant, during switching tube change in duty cycle, and the simulation waveform of two capacitance voltages and output voltage.Fig. 8 (a) is V _in1=60V, V _in2=140V, D ₁=0.4, D ₂the simulation waveform of=0.3 o'clock, as can be seen from the figure V _cf1=40V, V _cf2=60V, V _o=100V.Fig. 8 (b) is V _in1=60V, V _in2=140V, D ₁=0.6, D ₂the simulation waveform of=0.3 o'clock, as can be seen from the figure V _cf1=90V, V _cf2=60V, V _o=150V.All meet formula (3).

Simulation result shows: dual input Buck-Boost DC-DC converter is in input source variation, load variations and three kinds of situations of switching tube change in duty cycle, and stable state I/O relation all meets formula (3), thereby has verified its correctness.

The dual input step-down/up type DC-DC converter the utility model proposes not only can be operated in single input state but also can be operated in dual input state, when Dang Yi road input source works independently, this circuit topology is equivalent to a traditional Buck-Boost DC-DC converter, when two-way input source is worked simultaneously, this circuit topology is equivalent to the output series connection of two traditional B uck-Boost DC-DC converters, increase system voltage gain, improved the stability of a system and flexibility.In addition, the utility model, for the distributed generation system with two single input direct-current converters, has advantages of that circuit structure is simple, system bulk is little, cost is low.

Claims (4)

1. a novel dual input step-down/up type DC-DC converter, is characterized in that: comprise two direct current input sources ,two switching tubes, two intermediate energy storage inductance ,two fly-wheel diodes, two output dividing potential drop electric capacity and a load resistance r _ld, wherein,

Two direct current input sources are connected in series, direct current input source v _in1positive pole meet switching tube Q ₁drain electrode, switching tube Q ₁source electrode meet fly-wheel diode VD ₁negative electrode, fly-wheel diode VD ₁anode connect load resistance r _ldone end, load resistance r _ldthe other end and fly-wheel diode VD ₂negative electrode be connected, fly-wheel diode VD ₂anode meet switching tube Q ₂drain electrode, switching tube Q ₂source electrode connect direct current input source v _in2negative pole;

Two output dividing potential drop capacitances in series connect rear and load resistance r _ldparallel connection, output dividing potential drop electric capacity c _f1negative pole meet fly-wheel diode VD ₁anode, output dividing potential drop electric capacity c _f2positive pole meet fly-wheel diode VD ₂negative electrode;

Two intermediate energy storage inductance are connected in series, intermediate energy storage inductance l _f1positive pole connect fly-wheel diode VD ₁negative electrode, intermediate energy storage inductance l _f2negative pole connect fly-wheel diode VD ₂anode; Output dividing potential drop electric capacity c _f1positive pole and intermediate energy storage inductance l _f1negative pole be connected, intermediate energy storage inductance l _f1negative pole and direct-current input power supplying v _in2positive pole be connected.

2. a kind of novel dual input step-down/up type DC-DC converter according to claim 1, is characterized in that: the amplitude of described two direct current input sources is identical with characteristic or different, and two direct current input sources power to the load at the same time or separately.

3. a kind of novel dual input step-down/up type DC-DC converter according to claim 1, is characterized in that: described two switching tubes are for drive or be the working method of the certain angle that staggers simultaneously.

4. according to a kind of novel dual input step-down/up type DC-DC converter described in claim 1,2 or 3, it is characterized in that: described two output dividing potential drop capacitances equate.

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