CN103312159A - Novel double-input buck-boost DC (direct current)-DC converter - Google Patents

Abstract

The invention discloses a circuit topology of a novel double-input buck-boost DC (direct current)-DC converter, and belongs to the technical field of power electronics. The converter is structurally derived from a Buck-Boost DC-DC converter, and structurally comprises two direct-current input sources Vin1 and Vin2, two switch 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, the Q1 and the Q2 can be driven simultaneously as well as 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 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 invention discloses a kind of novel dual input step-down/up type DC-DC converter circuit topology, belong to the electronic power converter technical field.

Technical background

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

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

At present, 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 mainly is divided into two classes.One class belongs to the 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, easily is expanded into the situation of a plurality of inputs, but the independent powering load of a kind of input source can only be arranged at any one time.The another kind of simultaneously electric power-feeding structure that belongs to, two input sources can provide energy to load simultaneously in a switch periods, also can provide energy to load separately by an input source, realized the comprehensive utilization of the energy, but study at present more be dual input Buck converter topology and dual input Boost converter topology, these two kinds of converters are merely able to independent realization step-down and boost function, and voltage gain is lower, all can not satisfy well the requirement of system flexibility and stability.

Summary of the invention

For the problems referred to above, the invention discloses a kind of new dual input step-down/up type DC-DC converter circuit topological structure, it is by traditional Buck-Boost three-level DC converter derivation and next.

A kind of novel dual input step-down/up type DC-DC converter of the present invention, its structure 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 _LdWherein, 2 direct current input source V _In1And V _In2Be connected in series V _In1Positive pole meet switching tube Q ₁Drain electrode, switching tube Q ₁The source electrode stream diode VD that continues ₁Negative electrode, fly-wheel diode VD ₁Anode meet load resistance R _LdAn end, load resistance R _LdThe other end and fly-wheel diode VD ₂Negative electrode link to each other 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 _F1The negative pole stream diode VD that continues ₁Anode, output dividing potential drop capacitor C _F2The positive pole stream diode VD that continues ₂Negative electrode; Two intermediate energy storage inductance L _F1And L _F2Be connected in series the intermediate energy storage inductance L _F1Positive pole connect fly-wheel diode VD ₁Negative electrode, the 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 link to each other the intermediate energy storage inductance L _F1Negative pole and direct-current input power supplying V _In2Positive pole link to each other.

The amplitude of two direct current input sources can be identical with characteristic, and is 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 simultaneously the certain angle work of also can staggering.

The present invention allows two kinds of energy inputs, the amplitude of input source can be identical with characteristic, 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 improve Systems balanth and flexibility, realized the comprehensive utilization of the energy.In addition, the present invention has advantages of that with respect to for the distributed generation system of two single input direct-current converters circuit structure is simple, system bulk is little, cost is low.

Description of drawings

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

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 invention, wherein: (a) Q ₁And Q ₂Simultaneously conducting; (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 invention, wherein: (a) Q ₁And Q ₂The steady operation waveform that drives simultaneously; (b) Q ₁And Q ₂Differ the steady operation waveform of 180 ° of drivings.

Fig. 4 is the oscillogram of the static Simulation experiment of two-way input source of the present invention when working simultaneously, wherein: (a) Q ₁And Q ₂The static Simulation waveform that drives simultaneously; (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 present invention's one road input source when working independently, wherein: (a) V _In1Static Simulation waveform when working independently; (b) V _In2Static Simulation waveform when working independently.

Fig. 6 is the oscillogram of the two-way input source of the present invention emulation experiment that input source changes when working simultaneously, wherein: (a) V _In1=60V, V _In2=140V; (b) V _In1=80V, V _In2=140V.

Fig. 7 is the oscillogram of two-way input source of the present invention emulation experiment of load variations when working simultaneously, wherein: (a) R _Ld=50 Ω; (b) R _Ld=100 Ω.

Fig. 8 is the oscillogram of two-way input source of the present invention emulation experiment of change in duty cycle when working simultaneously, 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 present invention is made and to further specify.

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

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 _LdWherein, 2 direct current input source V _In1And V _In2Be connected in series V _In1Positive pole meet switching tube Q ₁Drain electrode, switching tube Q ₁The source electrode stream diode VD that continues ₁Negative electrode, fly-wheel diode VD ₁Anode meet load resistance R _LdAn end, load resistance R _LdThe other end and fly-wheel diode VD ₂Negative electrode link to each other 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 _F1The negative pole stream diode VD that continues ₁Anode, output dividing potential drop capacitor C _F2The anode stream diode VD that continues ₂Negative electrode; Two intermediate energy storage inductance L _F1And L _F2Be connected in series the intermediate energy storage inductance L _F1Positive pole connect fly-wheel diode VD ₁Negative electrode, the 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 link to each other the intermediate energy storage inductance L _F1Negative pole and direct-current input power supplying V _In2Positive pole link to each other.

With reference to the accompanying drawings 1 the concrete analysis circuit operation mode.V wherein _In1, V _In2Be respectively the 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 ₂Be fly-wheel diode, L _F1And L _F2The intermediate energy storage inductance, C _F1And C _F2Be two output dividing potential drop electric capacity, its capacity is very large and equal, R _LdIt is load resistance.Q ₁, Q ₂Can be open-minded simultaneously, the certain angle work of also can staggering.The situation that the present invention drives simultaneously take same switch frequency, two switching tubes is introduced its operation principle as example.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 invention.

(1) switch mode I.Shown in Fig. 2 (a), switching tube Q ₁And Q ₂Simultaneously conducting, fly-wheel diode VD ₁And VD ₂All turn-off VD ₁And VD ₂The voltage stress that bears is respectively V _In1+ V _Cf1And V _In2+ V _Cf2Direct-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.At this moment, inductance L _F1Both end voltage V _Lf1=V _In1, inductance L _F2Both end voltage V _Lf2=V _In2

(2) switch mode II.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 _F1Discharge, the intermediate energy storage inductance L _F2By fly-wheel diode VD ₂To capacitor C _F2With load resistance R _LdPower supply, inductance L _F2The electric current linearity reduce.At this moment, inductance L _F1Both end voltage V _Lf1=V _In1, inductance L _F2Both end voltage V _Lf2=-V _Cf2

(3) switch mode III.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 _F2Discharge, inductance L _F1By fly-wheel diode VD ₁To capacitor C _F1With load resistance R _LdPower supply, inductance L _F1The electric current linearity reduce.This moment inductance L _F1Both end voltage V _Lf1=-V _Cf1, inductance L _F2Both end voltage V _Lf2=V _In2

(4) switch mode IV.Shown in Fig. 2 (d), switching tube Q ₁And Q ₂Turn-off simultaneously fly-wheel diode VD ₁And VD ₂All conductings, the intermediate energy storage inductance L _F1And L _F2By fly-wheel diode VD ₁And VD ₂To the dividing potential drop capacitor C _F1, C _F2With load resistance R _LdPower supply, inductance L _F1And L _F2The electric current linearity reduce.This moment inductance L _F1Both end voltage V _Lf1=-V _Cf1, inductance L _F2Both end voltage V _Lf2=-V _Cf2

(5) switch mode V.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 as can be known, V _In1When 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 about (under the perfect condition for 0V), this converter is equivalent to a traditional B uck-Boost DC-DC converter.V _In2When powering to the load separately, principle is similar.When the two-way input source was worked simultaneously, this converter was equivalent to the output series connection with two traditional B uck-Boost DC-DC converters.Switching tube Q ₁With fly-wheel diode VD ₁The voltage stress that bears is V _In1+ V _Cf1, switching tube Q ₂With fly-wheel diode VD ₂The voltage stress that bears 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 the 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, the 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, the circuit working sequential is respectively mode I, II, IV and mode III.

With reference to the accompanying drawings 3, to inductance L _F1And L _F2Use respectively the weber equilibrium principle of inductance, can get:

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)

Can get stable state I/O relation by formula (1) and formula (2):

$V_o=V_{\mathrm{Cf}1}+V_{\mathrm{Cf}2}=\frac{D_1}{1-D_1}{V}_{\mathrm{in}1}+\frac{D_2}{1-D_2}{V}_{\mathrm{in}2}---\left(3\right)$

To capacitor C _F1And C _F2Use respectively electric capacity ampere-second equilibrium principle, can get:

$I_{\mathrm{Lf}1}=\frac{I_o}{1-D_1}---\left(4\right)$

$I_{\mathrm{Lf}2}=\frac{I_o}{1-D_2}---\left(5\right)$

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

$I_{\mathrm{in}1}=D_1{I}_{\mathrm{Lf}1}=\frac{D_1{I}_o}{1-D_1}---\left(6\right)$

$I_{\mathrm{in}2}=D_2{I}_{\mathrm{Lf}2}=\frac{D_2{I}_o}{1-D_2}---\left(7\right)$

In the formula, I _Lf1, I _Lf2Be respectively inductance L _F1, L _F2The stable state average current.

Accompanying drawing 4 carries out the oscillogram of emulation experiment for the present invention.

Wherein, the static Simulation waveform that accompanying drawing 4.1 is worked simultaneously for the two-way input source, Fig. 4 .1 (a) is the situation that two switching tubes drive simultaneously, Fig. 4 .1 (b) is the situation of the staggered 180 ° of drivings of two switching tubes.Can find out from Fig. 4 .1: no matter two switching tubes are to drive simultaneously or staggered 180 ° of drivings switching tube Q ₁During conducting, inductance L _F1Electric current linear increase capacitor C _F1Discharge; As switching tube Q ₁During shutoff, inductance L _F1The electric current linearity reduce capacitor C _F1Charging.Switching tube Q ₂During conducting, inductance L _F2Electric current linear increase capacitor C _F2Discharge; As switching tube Q ₂During shutoff, inductance L _F2The electric current linearity reduce capacitor C _F2Charging.

Accompanying drawing 4.2 is the static Simulation waveform that one road input source works independently, Fig. 4 .2 (a) V _In1Static Simulation waveform when working independently, Fig. 4 .2 (b) V _In2Static Simulation waveform when working independently.From Fig. 4 .2 (a), can find out: V _In1When powering to the load separately, switching tube Q ₁During conducting, inductance L _F1Electric current linear increase capacitor C _F1Discharge; As switching tube Q ₁During shutoff, inductance L _F1The electric current linearity reduce capacitor C _F1Charging.Capacitor C _F2In whole switch periods, all be clamped at-0.7V about (under the perfect condition for 0V).From Fig. 4 .2 (b), can find out: V _In2When powering to the load separately, switching tube Q ₂During conducting, inductance L _F2Electric current linear increase capacitor C _F2Discharge; As switching tube Q ₂During shutoff, inductance L _F2The electric current linearity reduce capacitor C _F2Charging.Capacitor C _F1In whole switch periods, all be clamped at-0.7V about (under the perfect condition for 0V).

Can find out from Fig. 4 .1 and Fig. 4 .2, dual input Buck-Boost DC-DC converter two drives signal both can drive the 180 ° of drivings that also can interlock simultaneously; Both allow the two-way input source to power to the load simultaneously, and allowed again one 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 4.3 has provided the input source variation, the simulation waveform of two capacitance voltages and output voltage.Fig. 4 .3 (a) is V _In1=60V, V _In2=140V, D ₁=0.4, D ₂=0.3 o'clock simulation waveform, as can be seen from the figure V _Cf1=40V, V _Cf2=60V, V _o=100V.Fig. 4 .3 (b) is V _In1=80V, V _In2=140V, D ₁=0.4, D ₂=0.3 o'clock simulation waveform, as can be seen from the figure V _Cf1=53V, V _Cf2=60V, V _o=113V.All satisfy formula (3).

When accompanying drawing 4.4 has provided load variations, the simulation waveform of two capacitance voltages and output voltage.Fig. 4 .4 (a) is V _In1=60V, V _In2=140V, D ₁=0.4, D ₂=0.3, R _LdSimulation waveform during=50 Ω, Fig. 4 .4 (b) is V _In1=60V, V _In2=140V, D ₁=0.4, D ₂=0.3, R _LdSimulation waveform during=100 Ω.Can find out that from Fig. 4 .4 dual input Buck-Boost DC-DC converter two capacitance voltage values and output voltage values all remain unchanged, and satisfy formula (3).

Accompanying drawing 4.5 has provided input voltage and load is constant, during the switching tube change in duty cycle, and the simulation waveform of two capacitance voltages and output voltage.Fig. 4 .5 (a) is V _In1=60V, V _In2=140V, D ₁=0.4, D ₂=0.3 o'clock simulation waveform, as can be seen from the figure V _Cf1=40V, V _Cf2=60V, V _o=100V.Fig. 4 .5 (b) is V _In1=60V, V _In2=140V, D ₁=0.6, D ₂=0.3 o'clock simulation waveform, as can be seen from the figure V _Cf1=90V, V _Cf2=60V, V _o=150V.All satisfy 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 satisfies formula (3), thereby has verified its correctness.

The dual input step-down/up type DC-DC converter that the present invention proposes not only can be operated in single input state but also can be operated in the dual input state, when one road input source works independently, this circuit topology is equivalent to a traditional Buck-Boost DC-DC converter, when the two-way input source is worked simultaneously, this circuit topology is equivalent to the output series connection with two traditional B uck-Boost DC-DC converters, increase the system voltage gain, improved the stability of a system and flexibility.In addition, the present invention has advantages of that with respect to for the distributed generation system of two single input direct-current converters 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, the direct current input source V _In1Positive pole meet switching tube Q ₁Drain electrode, switching tube Q ₁The source electrode stream diode VD that continues ₁Negative electrode, fly-wheel diode VD ₁Anode connect load resistance R _LdAn end, load resistance R _LdThe other end and fly-wheel diode VD ₂Negative electrode link to each other fly-wheel diode VD ₂Anode meet switching tube Q ₂Drain electrode, switching tube Q ₂Source electrode connect the 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 _F1The negative pole stream diode VD that continues ₁Anode, output dividing potential drop electric capacity C _F2The positive pole stream diode VD that continues ₂Negative electrode;

Two intermediate energy storage inductance are connected in series, the intermediate energy storage inductance L _F1Positive pole connect fly-wheel diode VD ₁Negative electrode, the 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 link to each other the intermediate energy storage inductance L _F1Negative pole and direct-current input power supplying V _In2Positive pole link to each other.

2. a kind of novel dual input step-down/up type DC-DC converter according to claim 1, it 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 driving simultaneously or being the working method of the certain angle that staggers.

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

Images