CN103107720A - Three-inductance and double-Buck inverter - Google Patents

Abstract

A three-inductance and double-Buck inverter comprises two switching tubes, two diodes, two direct current filter inductances, an alternating current filter inductance, two input capacitors and an output filter capacitor. A first bridge arm is formed by sequential connecting of a switching tube S1 and a diode D1 in series, and a second bridge arm is formed by sequential connecting of a diode D2 and a switching tube S2 in series. A direct current filter inductance Ldc1 and a direct current filter inductance Ldc2 are connected between midpoints of the two bridge arms in a bridge joint mode. A common terminal of the Ldc1 and the Ldc2 is connected with an alternating current filter inductance Lac, and the other end of the Lac is connected with a filter capacitor Cf and a load R. The inverter has the advantages that an output filter inductance value of a traditional double-Buck inverter is greatly reduced, the size and the weight of the whole inverter are greatly reduced, and high power density and high reliability integration of the inverter are benefited. The three-inductance and double-Buck inverter is suitable for a combined type three-phase inverter, a cascading multi-level inverter and the corresponding control methods of the three-inductance and double-Buck inverter, wherein the three-phase inverter and the cascading multi-level inverter are formed by the three-inductance and double-Buck inverter. An inverter circuit and a control method have a very good application prospect in occasions such as uninterrupted power supply (UPS), an aircraft electric power source, wind energy and solar power generation.

Description

A kind of three inductance dual Buck inverters

Technical field

The present invention has announced a kind of three inductance dual Buck inverters, belongs to converters.

Background technology

Along with increasingly sharpening of energy crisis, the new forms of energy such as solar energy, wind energy, fuel cell receive increasing concern.How to be that available alterating and direct current is the focus of current research with these energy transformations; Distributed generation system is widely used in such occasion, and distributed system need to adopt the two-stage type structure of DC/DC+DC/AC: prime DC/DC to complete inverter input and output voltage coupling and electrical isolation usually; Rear class DC/AC completes the orthogonal conversion and powers to terminate load.And inverter is directly determining the output quality of power supply as the important component part of system; High reliability, high power density and high efficiency are to weigh the important indicator of inverter performance.The tradition dual Buck inverter due to have without bridge arm direct pass, reliability is high, the output waveform quality is good, the efficient advantages of higher is widely used in the high reliability occasion; But due to two of needs output inductor and each inductance half period of only working independently, the magnetic element utilance is low, and system bulk weight is large, has affected the application of dual Buck inverter.

At present, have following several for the low main solution of shortcoming of dual Buck inverter magnetic element utilance:

(1) share magnetic core direct-coupling scheme.This method is by directly two inductor windings being coupled on a magnetic core.Connect difference according to Same Name of Ends, be divided into again two kinds of coupled modes.The advantage of this scheme is that inductance coupling high is fairly simple; But because there is coupled relation in two inductance, can produce a voltage corresponding according to turn ratio relation when applying voltage on winding therein on another winding.Guarantee because the inductance of actual coiling is impossible can produce uncertain circulation at circuit by two inductance value full symmetrics that winding is corresponding.And loop middle impedance corresponding to circulation is very little, and very little voltage difference can produce very large loop current.The existence of circulation will have a strong impact on reliability and the overall efficiency of circuit working.

(2) bimag four winding schemes.On two magnetic cores, the sense value of each inductance is half of former inductance with each inductor winding average mark, and one of them inductor winding Same Name of Ends is connected, and another inductance different name end is connected.Suppose whenever parameter all equates (ideal situation) to two magnetic cores, under the condition of equal turn numbers, it is full decoupled that two inductance can be realized, namely applies voltage on an inductance, and the magnitude of voltage of responding on another inductance is zero.But, in fact the operating state of two magnetic cores can not guarantee identical, just can not be fully equal as two own parameters of magnetic core (magnetic permeability etc.), cause the two halves winding voltage of an inductance different, induction has voltage on one road inductance of inoperative, causes existing the possibility of circulation.And the magnetic core parameters such as magnetic permeability are larger along with environmental influences such as temperature, therefore be difficult to guarantee that inoperative inductance induced voltage is zero.Therefore also there is the described circulation of scheme (1).

(3) share the full decoupled magnetic Integrated Solution of magnetic core.This scheme is for EE type magnetic core, and on center pillar, 2 of inductance L are divided into two parts the inductance L 1 of traditional dual Buck inverter, respectively on two lateral columns of magnetic core.When applying voltage power supply on inductance therein, the another one inductance is offset and can not produced induced voltage due to magnetic flux, therefore neither can influence each other, and be full decoupled.But in fact this scheme does not reduce the required inductance value of dual Buck inverter, will increase the volume and weight that reduces inductance that therefore can not be real although improved the model of the required magnetic core of the utilization rate of magnetic core.

Summary of the invention

The object of the invention is to, for the large shortcoming of traditional double Buck inverter filtering inductance volume weight, a kind of three inductance dual Buck inverters have been proposed, on the basis that does not reduce inverter efficiency, effectively reduced the inductance value of dual Buck inverter, improve the magnetic element utilance, realized high power density.

Realize three inductance dual Buck inverters of above-mentioned purpose by two switching tubes, two diodes, two DC filtering inductance, an ac filter inductance, two input capacitances, an output filter capacitor forms.This converter is by switching tube S ₁, diode D ₁Be followed in series to form the first brachium pontis, by diode D ₂, switching tube S ₂Be followed in series to form the second brachium pontis; The DC filtering inductance L _dc1, L _dc2Be connected across between two brachium pontis mid points L _dc1, L _dc2Public termination ac filter inductance L _ac, L _acAnother termination filter capacitor C _fAnd load R.It is characterized in that:

Two separate inductors of traditional dual Buck inverter are transformed to two DC filtering inductance L _dc1, L _dc2Ac filter inductance L of profit _acSubstitute.Improve the utilance of dual Buck inverter inductance, reduced total inductance value.

The three inductance dual Buck inverters that the present invention proposes have the following advantages:

1) kept the advantage of traditional dual Buck inverter;

2) inductance value of three inductance dual Buck inverters is little, has improved the magnetic element utilance, has alleviated the volume weight of system, has reduced the cost of system;

Description of drawings

Fig. 1 is that three inductance dual Buck inverters of the present invention are implemented schematic diagram.

Fig. 2 is the enforcement schematic diagram of traditional dual Buck inverter.

Fig. 3 is three inductance dual Buck inverter operation mode schematic diagrames of the present invention.

Fig. 4 is followed successively by the output voltage V of three inductance dual Buck inverters concrete enforcement under upper _out, the DC filtering inductance L _dc1, L _dc2Current i _L1, i _L2And ac filter inductance L _acCurrent i _L

Fig. 5 is followed successively by three inductance dual Buck inverter switching tube S concrete enforcement under upper ₁, S ₂Duty ratio d ₁, d ₂, switching tube S ₂Both end voltage V _{_ ds2}And diode D ₂Both end voltage V _{_ d2}

Be followed successively by three inductance dual Buck inverter switching tube S in concrete enforcement under on Fig. 6 ₁, S ₂Duty ratio d ₁, d ₂, flow through diode D ₂Current i d2 and switching tube S ₂The current i d4 of body diode.

Fig. 7 is the first brachium pontis switching tube S of three inductance dual Buck inverters of the present invention ₁By switching tube S ₁The unit that is composed in series with diode substitutes, the second brachium pontis switching tube S ₂By switching tube S ₂The enforcement schematic diagram that the unit that is composed in series with diode substitutes.

Fig. 8 be three inductance dual Buck inverters of the present invention when power output is the 1kVA applications, the DC filtering inductance L _dc1, L _dc2With the ac filter inductance L _acPictorial diagram.

Fig. 9 be of the present invention three tunnel three inductance dual Buck inverters respectively as A, B and C three-phase, the three-phase inverter that is combined into is implemented schematic diagram.

Figure 10 is that the cascaded multilevel inverter that three inductance dual Buck inverters of the present invention consist of is implemented schematic diagram.

Figure 11 is the SPWM control block diagram of the inverter that forms of three inductance dual Buck inverters of the present invention and conversion.

Figure 12 is the stagnant ring control block diagram of the inverter that forms of three inductance dual Buck inverters of the present invention and conversion.

Figure 13 is the control block diagram of the cascaded multilevel inverter of three inductance dual Buck inverters formations of the present invention.

Embodiment

Below in conjunction with embodiment and contrast accompanying drawing, the present invention will be further described.

Fig. 1 is three inductance dual Buck inverter circuit.

As inverter inductor L _dc1Electric current is timing, and inverter is divided into following four operation modes, and wherein the inductive current direction is as shown in Figure 1:

Mode 1: switching tube S ₁During conducting, due to switching tube S ₂With diode D ₂Parasitic capacitance C _s2, C _d2Existence, C _s2Through input power U _in, the DC filtering inductance L _dc1, L _dc2And C _d2Charge in the loop, C _d2Through the DC filtering inductance L _dc1, L _dc2And C _s2Discharge in the loop, i _Ldc1, i _Ldc2Electric current forward resonance rises, C _s2Both end voltage rises, C _d2Both end voltage descends.Until C _d2When both end voltage drops to zero, this operation mode finishes, due to the ac filter inductance L _acBe worth greatlyr, electric current is linear to rise.

Mode 2: work as C _d2After both end voltage drops to zero, D ₂The nature conducting; At this moment, S ₁Still conducting, S ₂And D ₁All turn-off i _Ldc1, i _Lac, forward is linear increases, i _Ldc2The forward linearity reduces.

Mode 3:D ₁During conducting, S ₁, S ₂And D ₂All turn-off, due to switching tube S ₂With diode D ₂Parasitic capacitance C _s2, C _d2Existence, C _d2Through input power U _m, the DC filtering inductance L _dc1, L _dc2And D ₁Charge in the loop that forms, C _s2Through the DC filtering inductance L _dc1, L _dc2And D ₁Discharge in the loop, i _Ldc1Current resonance descends, i _Ldc2The reverse resonance of electric current descends, C _d2Both end voltage rises, C _s2Both end voltage descends.Until C _s2When both end voltage drops to zero, this operation mode finishes.

Mode 4: work as C _s2After both end voltage drops to zero, S ₂Body diode D _s2The nature conducting; At this moment, D ₁Still conducting, S ₂And S ₁All turn-off C ₂Charging, i _Ldc1, i _LacThe forward linearity reduces, i _Ldc2Reverse linear reduces.

As inverter inductor L _dc2When electric current was negative, operation mode also is divided into four mode, and was identical during with positive half period.

In order to illustrate that three inductance dual Buck inverters can reduce magnetic core size, existing brief analysis is as follows:

If the required sense value of each inductance of traditional dual Buck inverter is L, the maximum current amplitude that flows through is I _p, effective value is I _o, obtaining current density is j _max, maximum functional magnetic is close is B _max, the inductance number of turn is N, the window coefficient is K _u, the required magnetic core size of each inductance of traditional dual Buck inverter is:

$S=\frac{L\·I_p}{N\·B_{\max }}$ $Q=\frac{N\·I_o}{j_{\max }\·K_u}$ $\mathrm{SQ}=S\×Q=\frac{L\·I_p\·I_o}{j_{\max }\·K_u\·B_{\max }}$

Due to two identical separate inductors of needs, required total magnetic core size is:

$\mathrm{SQ}=\frac{2\·L\·I_p\·I}{j_{\max }\·K_u\·B_{\max }}$

If the DC filtering inductance value of three inductance dual Buck inverters is L _dc1=L _dc2=L _dc, the ac filter inductance value is L _ac, the maximum current amplitude that flows through the DC filtering inductance is I _p, effective value is I _o, the inductance number of turn is N _dcThe maximum current amplitude that flows through the ac filter inductance is I _p, effective value is

Obtaining current density is j _max, maximum functional magnetic is close is B _max, the inductance number of turn is N _ac, the three required magnetic core sizes of each DC filtering inductance of inductance dual Buck inverter are:

$S_{\mathrm{dc}}=\frac{L_{\mathrm{dc}}\·I_p}{N_{\mathrm{dc}}\·B_{\max }}$ $Q_{\mathrm{dc}}=\frac{N_{\mathrm{dc}}\·I_o}{j_{\max }\·K_u}$ $\mathrm{SQ}=S_{\mathrm{dc}}\×Q_{\mathrm{dc}}=\frac{L_{\mathrm{dc}}\·I_p\·I_o}{j_{\max }\·K_u\·B_{\max }}$

Due to two identical DC filtering inductance of needs, required total magnetic core size is:

$\mathrm{SQ}=\frac{2\·L_{\mathrm{dc}}\·I_p\·I_o}{j_{\max }\·K_u\·B_{\max }}$

The three required magnetic core sizes of inductance dual Buck inverter ac filter inductance are:

$S_{\mathrm{ac}}=\frac{L_{\mathrm{ac}}\·I_p}{N_{\mathrm{ac}}\·B_{\max }}$ $Q_{\mathrm{ac}}=\frac{N_{\mathrm{ac}}\·\sqrt{2}{I}_o}{j_{\max }\·K_u}$ $\mathrm{SQ}=S_{\mathrm{ac}}\×Q_{\mathrm{ac}}=\frac{L_{\mathrm{ac}}\·I_p\·\sqrt{2}{I}_o}{j_{\max }\·K_u\·B_{\max }}$

The required total magnetic core size of three inductance dual Buck inverters is:

$\mathrm{SQ}=\frac{2\·L_{\mathrm{dc}}\·I_p\·I_o}{j_{\max }\·K_u\·B_{\max }}+\frac{L_{\mathrm{ac}}\·I_p\·\sqrt{2}{I}_o}{j_{\max }\·K_u\·B_{\max }}=\frac{I_p\·I_o\·(2\·L_{\mathrm{dc}}+\sqrt{2}{L}_{\mathrm{ac}})}{j_{\max }\·K_u\·B_{\max }}$

Because inductance value satisfies L _dc1+ L _acThe condition of≤L, in two kinds of situations, total inductance value satisfies all the time

Relation; So permanent SQ value less than traditional dual Buck inverter of the SQ value of three inductance dual Buck inverters.Therefore adopt three inductance dual Buck inverters can improve the magnetic core utilance, realize high power density.

The execution mode of three inductance dual Buck inverters of the present invention can also have:

1. three inductance dual Buck inverters of the present invention, the switching tube S of the first brachium pontis ₁Can be by switching tube S ₁The unit that is composed in series with diode substitutes, the switching tube S of the second brachium pontis ₂Can be by switching tube S ₂The unit that is composed in series with diode substitutes.

2. the DC filtering inductance L in three inductance dual Buck inverters of the present invention _dc1, L _dc2Can adopt coupling inductance to realize.

3. three inductance dual Buck inverters of the present invention are combined into three-phase inverter, adopt three tunnel three inductance dual Buck inverters respectively as A, B and C three-phase; Three-phase general DC busbar voltage U _In, and three-phase common DC input side two capacitor C ₁, C ₂Common point form mid point.

4. the cascaded multilevel inverter that consists of of three inductance dual Buck inverters of the present invention, the output head and the tail of N road three inductance dual Buck inverters are connected in turn to be consisted of, and N is the natural number more than or equal to 2.

The various forms of inverters that form for three above-mentioned inductance dual Buck inverters and combined transformation thereof provide corresponding control method, and the specific works principle that the control principle block diagram of contrast accompanying drawing provides is as follows:

The specific works principle that the control principle block diagram of accompanying drawing provides is as follows:

1. the SPWM control method of 1,2,3 and 4 inverters in three inductance dual Buck inverters and execution mode, its operation principle is: the error signal that inverter output voltage and voltage reference relatively produce is as given value of current, sampling ac filter inductance L _acElectric current and current reference relatively obtain current error signal, current error signal and triangular carrier access respectively in-phase end and the end of oppisite phase of comparator 2; The output of Voltage loop connects the end of oppisite phase of comparator 1, the in-phase end ground connection of comparator 1.The output of the output of comparator 1 and comparator 2 obtains switching tube electricity S through one with door ₂PWM drive.The output of the output of comparator 1 and comparator 2 negate respectively obtains switching tube electricity S by one with door ₁PWM drive.

2. the hysteresis control method thereof of 1,2,3 and 4 inverters in three inductance dual Buck inverters and execution mode, its operation principle is: the error signal that inverter output voltage and voltage reference relatively produce is as given value of current; Sampling ac filter inductance L _acThe end of oppisite phase of the positive half period input hysteresis comparator 1 of electric current, the in-phase end of given value of current input hysteresis comparator 1 obtains switching tube electricity S ₁PWM drive; Sampling ac filter inductive current L _acThe in-phase end of negative half-cycle input hysteresis comparator 2, the end of oppisite phase of given value of current input hysteresis comparator 2 obtains switching tube electricity S ₂PWM drive.

3. the control method of the cascaded multilevel inverter that consists of of three inductance dual Buck inverters, its operation principle is: the error signal u that inverter output voltage and voltage reference obtain through voltage regulator _eAs given value of current; Sampling ac filter inductance L _acElectric current and given value of current obtain error signal i through current regulator _ei _eCompare with the triangular wave of N road phase shift phase angle 2 π/N respectively; The output of N road comparator is after logical circuit, and the PWM that obtains each switching tube drives.

It is pointed out that with respect to traditional dual Buck inverter, three inductance dual Buck inverters of the present invention come the filtering each harmonic to guarantee the output voltage waveforms quality of inverter by increasing an ac filter inductance; Only the filter inductance of half period work substitutes with the DC filtering inductance simultaneously, has fundamentally reduced the total filter inductance value of dual Buck inverter, has improved the utilance of magnetic element.In its control method, only need the ac filter inductance L of sampling _acElectric current get final product, simplified control circuit.

Be more than the further description that the present invention is done, can not assert that the concrete enforcement of this aspect only limits to these explanations.Concerning the those of ordinary skill of technical field of the present invention, some conversion and the equivalence made without departing from the inventive concept of the premise, and performance is identical with purposes, all should be considered as belonging to protection scope of the present invention.

Claims (8)

1. inductance dual Buck inverter, it is characterized in that: this converter is by switching tube S ₁, diode D ₁Be followed in series to form the first brachium pontis, by diode D ₂, switching tube S ₂Be followed in series to form the second brachium pontis; The DC filtering inductance L _dc1, L _dc2Be connected across between two brachium pontis mid points L _dc1, L _dc2Public termination ac filter inductance L _ac, L _acAnother termination filter capacitor C _fAnd load R.

2. three inductance dual Buck inverters claimed in claim 1 is characterized in that the switching tube S of the first brachium pontis in described circuit ₁The unit that is composed in series by switching tube and diode substitutes, the switching tube S of the second brachium pontis ₂The unit that is composed in series by switching tube and diode substitutes.

3. claim 1,2 described three inductance dual Buck inverters, is characterized in that DC filtering inductance L in described circuit _dc1, L _dc2The employing coupling inductance realizes.

4. the three-phase inverter of claim 1,2 and 3 described three inductance dual Buck inverters compositions, is characterized in that adopting three three inductance dual Buck inverters respectively as A, B and C three-phase; Three-phase general DC busbar voltage U _m, and three-phase common DC input side capacitor C ₁, C ₂Common point form mid point, be combined into three-phase inverter.

5. the control method of claim 1,2,3 and 4 described inverters, it is characterized in that: the error signal that inverter output voltage and voltage reference relatively produce is as current reference; Sampling ac filter inductance L _acElectric current and current reference relatively obtain current error signal, and current error signal and triangular carrier are handed over and intercepted pwm signal driving switch pipe.

6. the control method of claim 1,2,3 and 4 described inverters is characterized in that: the error signal that inverter output voltage and voltage reference relatively produce is as current reference, sampling ac filter inductance L _acElectric current and current reference relatively obtain pwm signal driving switch pipe through hysteresis comparator.

7. the cascaded multilevel inverter that consists of of claim 1,2 and 3 described three inductance dual Buck inverters is characterized in that output head and the tail with N road three inductance dual Buck inverters are connected in turn to consist of, and N is the natural number more than or equal to 2.

8. the control method of cascaded multilevel inverter claimed in claim 7 is characterized in that: the error signal that inverter output voltage and voltage reference relatively produce is as current reference, sampling ac filter inductance L _acElectric current and current reference relatively obtain current error signal; Current error signal and N road triangular carrier hand over the PWM that intercepts N road three inductance dual Buck inverters to drive signal, wherein N road triangular carrier mutual deviation 2 π/N degree successively.

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