CN102255537A - DC-AC conversion circuit - Google Patents

DC-AC conversion circuit Download PDF

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Publication number
CN102255537A
CN102255537A CN2011101909516A CN201110190951A CN102255537A CN 102255537 A CN102255537 A CN 102255537A CN 2011101909516 A CN2011101909516 A CN 2011101909516A CN 201110190951 A CN201110190951 A CN 201110190951A CN 102255537 A CN102255537 A CN 102255537A
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China
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switch element
comparator
output
conversion circuit
electrically connects
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CN2011101909516A
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CN102255537B (en
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顾振维
李雷鸣
黄河
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Delta Electronics Inc
Delta Optoelectronics Inc
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Delta Optoelectronics Inc
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Abstract

The invention discloses a DC-AC conversion circuit, which comprises a switching circuit. The switching circuit receives DC electric energy and converts the DC electric energy to output AC modulated voltage between a first output end and a second output end, and comprises a first switch branch circuit, a second switch branch circuit and a sixth switching element, wherein the first switch branch circuit consists of a first switching element and a second switching element which are electrically connected in series in turn; the first output end is electrically connected between the first and second switching elements; the second switch branch circuit consists of a third switching element, a fourth switching element and a fifth switching element which are electrically connected in series in turn; the second output end is electrically connected between the fourth and fifth switching elements; one end of the sixth switching element is electrically connected between the third and fourth switching elements, and the other end of the sixth switching element is electrically connected between the first and second switching elements; and the first to sixth switching elements performs switching-on/off, so that the DC-AC conversion circuit improves efficiency and reduce the generation of leakage current.

Description

Dc-ac conversion circuit
Technical field
The present invention relates to a kind of change-over circuit, and be particularly related to a kind of dc-ac conversion circuit.
Background technology
The human at present main energy sources of using is oil, produce required power or electric energy by burning petroleum, for example automobile or fuel oil type generator (factory), yet, high temperature that produces in the oil combustion process and waste gas also can make Global Greenhouse Effect worsen except meeting causes the air quality deterioration.In addition, according to whole world Petroleum Production statistics, oil production rate will peak in 10 years; thereafter output will reduce year by year; this means that not only oil price (comprising electricity price) will be no longer cheap, also may cause the arrival of real oil crisis, causes the global economy storm indirectly.
In view of this, the renewable energy resources (renewable energy) are converted to general people's livelihood power supply or machine power efficient and cost-effective, have become the important industry development policies that sophisticated technologies country takes into account environmental protection and generating.In the renewable energy resources such as solar energy, wind energy, tidal energy, geothermal energy, biological waste energy, utilize the renewable source of energy generation system of solar power generation, because the tool environmental protection, be easy to install, the maturation of commercialized technology and the auxiliary promotion of state plan, become the main selection of advanced country development decentralized power supply system.
See also Fig. 1, it is the circuit diagram of existing dc-ac conversion circuit.As shown in Figure 1, existing dc-ac conversion circuit 1 is applied to the sunlight grid-connected system, therefore also can be described as photovoltaic DC-to-AC converter (Photovoltaic Inverter, PV inverter), dc-ac conversion circuit 1 is the circuit framework of non-isolation and full-bridge type, mainly be made of an input filter circuit 10, a full-bridge type commutation circuit 11 and an output filter circuit 12, wherein input filter circuit 10 is by one first capacitor C 1Constitute, in order to receive DC input voitage V by solar panels produced DC, and to DC input voitage V DCCarry out filtering.11 of full-bridge type commutation circuits and output filter circuit 12 electrically connect, and by first to fourth switch element S 1-S 4Constitute the first switch element S 1And second switch element S 2Be that series connection electrically connects the 3rd switch element S 3And the 4th switch element S 4Also series connection electrically connects, and forms the full-bridge framework of two brachium pontis formulas thus, first to fourth switch element S 1-S 4Switching running by the control of a control unit (not shown) is carried out conducting or ended makes full-bridge type commutation circuit 11 with filtered DC input voitage V thus DCBe converted to and exchange demodulating voltage V T12 of output filter circuits and full-bridge type commutation circuit 11 electrically connect, and by one first inductance L 1, one second inductance L 2And one second filter capacitor C 2Constitute output filter circuit 1 2Exchange demodulating voltage V in order to filtering TThe high frequency composition, and then export an ac output voltage Vo to electric power networks (Grid) G.
Generally speaking, first to fourth switch element S of full-bridge type commutation circuit 11 1-S 4Be to operate in the pulse width modulation mode, and according to first to fourth switch element S 1-S 4The difference of mode of operation also can be divided into bipolarity and switch (Bipolar) or unipolarity switching (Unipolar).Please Fig. 2 and Fig. 3, wherein Fig. 2 is that full-bridge type commutation circuit shown in Figure 1 is when the mode of operation that bipolarity is switched, the oscillogram of the demodulating voltage that it is exported, Fig. 3 be the demodulating voltage of full-bridge type commutation circuit shown in Figure 1 output when the mode of operation that unipolarity is switched, the oscillogram of the demodulating voltage that it is exported.As shown in Figure 1 to Figure 3, when under ambipolar switching working mode, first to fourth switch element S 1-S 4Carry out the action that high frequency switches, the interchange demodulating voltage V that full-bridge type commutation circuit 11 is exported TWhen positive half cycle or negative half period, on the occasion of DC input voitage V DCDC input voitage V to negative value DCBetween do change, also promptly as shown in Figure 2, when under unipolar switching working mode, have only single brachium pontis carrying out the action that high frequency switches when then switching for switch in every half cycle, another brachium pontis is then kept the floatless switch state, also promptly has only the first switch element S of a formation brachium pontis wherein 1With second switch element S 2Or constitute the 3rd switch element S of another brachium pontis 3With the 4th switch element S 4Operate the interchange demodulating voltage V that full-bridge type commutation circuit 11 is exported in mode with mutual conducting TPositive half cycle be 0 on the occasion of DC input voitage VDC between do change, then be between the DC input voitage VDC of negative value, to do change at negative half period, also promptly as shown in Figure 30.
When full-bridge type commutation circuit 11 adopts unipolar switching working mode running, only have two included switch elements of single brachium pontis in the time of can switching because of each switch and carrying out the action that high frequency switches, but not as when adopting the running of bipolarity switching working mode, first to fourth switch element S 1-S 4Being the action that high frequency switches, is to exchange demodulating voltage V TOnly 0 on the occasion of DC input voitage V DCBetween or at 0 DC input voitage V to negative value DCBetween do change, so full-bridge type commutation circuit 11 adopts the switch costs that unipolar switching working mode had to lack than employing bipolarity switching working mode, in other words, promptly efficient is higher.Yet owing to produce DC input voitage V DCSolar panels can exist parasitic capacitance C between over the ground P, shown in the 1st figure, when full-bridge type commutation circuit 11 adopts unipolar switching working mode to operate, the demodulating voltage V that full-bridge type commutation circuit 11 is exported TComposition with high frequency exists, so first output terminals A of full-bridge type commutation circuit 11 ' for the more any relative voltage in the dc-ac conversion circuit 1, for example with parasitic capacitance C PThe relative voltage of the common contact N ' that electrically connects reaches the second output B ' for the relative voltage that is total to contact N ', and both in office one addition mean values that switch time point there is no method and keep a fixed value, cause parasitic capacitance C PThe tangible voltage variety of last generation, and then produce leakage current and harmful to human and equipment, review full-bridge type commutation circuit 11 and adopt ambipolar switching working mode running then to have the effect of the generation that can avoid leakage current.
Therefore how to develop and a kind ofly improve above-mentioned prior art disappearance, and can promote efficient simultaneously and reduce the dc-ac conversion circuit of leakage current generating, real in pressing for the problem of solution at present.
Summary of the invention
Main purpose of the present invention when being applied to the sunlight grid-connected system to solve existing dc-ac conversion circuit, and can't reach the disappearance that efficient is high and reduce leakage current generating for a kind of dc-ac conversion circuit is provided simultaneously.
For reaching above-mentioned purpose, preferred embodiment of the present invention is for providing a kind of dc-ac conversion circuit, comprise: commutation circuit, framework is in receiving direct current energy, and change, and between first output and second output output AC demodulating voltage, and comprise: first switching branches, comprise first switch element and second switch element that series connection in regular turn electrically connects, electrically connect first output between first switch element and the second switch element; The second switch branch road, electric connection in parallel with first switching branches, and comprise the 3rd switch element, the 4th switch element and the 5th switch element that series connection in regular turn electrically connects, electrically connect second output between the 4th switch element and the 5th switch element; And the 6th switch element, the one end is electrically connected between the 3rd switch element and the 4th switch element, and the other end is electrically connected between first switch element and the second switch element and with first output and electrically connects; Wherein, when positive half cycle, simultaneously and the constantly conducting or of this first switch element and the 5th switch element by switching, the 6th switch element is a conducting state, when negative half period, change by the simultaneously and constantly conducting or by switching, the 4th switch element is a conducting state of this second switch element and the 3rd switch element.
Description of drawings
Fig. 1 is the circuit diagram of existing dc-ac conversion circuit.
Fig. 2 be full-bridge type commutation circuit shown in Figure 1 when the mode of operation that bipolarity is switched, the oscillogram of the interchange demodulating voltage that it is exported.
Fig. 3 be full-bridge type commutation circuit shown in Figure 1 when the mode of operation that unipolarity is switched, the oscillogram of the interchange demodulating voltage that it is exported.
Fig. 4 is the electrical block diagram of the dc-ac conversion circuit of preferred embodiment of the present invention.
Fig. 5 A is the voltage of Fig. 4 and the sequential schematic diagram of control signal.
Fig. 5 B is the oscillogram of the interchange demodulating voltage of Fig. 4.
Fig. 6 A is the electrical block diagram of control unit shown in Figure 4.
Fig. 6 B is the sequential schematic diagram of voltage shown in Fig. 6 A and control signal.
Fig. 7 A is that another of control unit shown in Figure 4 changes the electrical block diagram of example.
Fig. 7 B is the sequential schematic diagram of voltage shown in Fig. 7 A and control signal.
Wherein, description of reference numerals is as follows:
1,4: dc-ac conversion circuit; 10,40: input filter circuit;
11: the full-bridge type commutation circuit; 12,42: output filter circuit;
41: commutation circuit; 411: the first switching branches;
412: the second switch branch road; 43: control unit;
430～432: first～the 3rd comparator; 730～732: first～the 3rd comparator;
433,733: not gate; 734～735: the first～the second with the door;
736: rectifying device; 8: flow directing device;
9: AC load; C 1: first electric capacity;
C 2: second electric capacity; C P: parasitic capacitance;
L 1: first inductance; L 2: second inductance;
Vo: ac output voltage; V DC: DC input voitage;
VT: exchange demodulating voltage; V C1～V C6: first to the 6th control signal;
V 1～V 2: the first～the second string ripple signal; V AN～V BN: the first～the second relative voltage;
V 3: string ripple signal; V 4: rectification string ripple signal;
V TRI: triangular signal; Vr: specific voltage value;
G: electric power networks; S 1～S 6: first to the 6th switch element;
A ', A: first output; B ', B: second output;
N ', N: be total to contact; T 1～T 2: the first～the second time;
D 1～D 6: first body diode～hexasomic diode.
Embodiment
Some exemplary embodiments that embody feature of the present invention and advantage will be described in detail in the explanation of back segment.Be understood that the present invention can have various variations on different modes, so its neither departing from the scope of the present invention, and explanation wherein and the graphic usefulness that ought explain in itself, but not in order to restriction the present invention.
See also Fig. 4, it is the electrical block diagram of the dc-ac conversion circuit of preferred embodiment of the present invention.As shown in Figure 4, dc-ac conversion circuit 4 can be but is not limited to be applied to the sunlight grid-connected system, and is non-isolated circuit framework, and it receives a direct current device 8, solar panels for example, the DC input voitage V that is produced DC, and be converted to ac output voltage Vo, to provide to an AC load 9, for example ac electric apparatus equipment or electricity network system etc.
Dc-ac conversion circuit 4 comprises that mainly an input filter circuit 40, switches circuit 41, an output filter circuit 42 and a control unit 43.Wherein input filter circuit 40 electrically connects with the anode of flow directing device 8 and negative terminal respectively and receives DC input voitage V DC, it is in order to DC input voitage V DCCarry out filtering, in the present embodiment, input filter circuit 40 can be but is not limited to by one first capacitor C 1Constitute.
Commutation circuit 41 electrically connects with input filter circuit 40, and comprises first to the 6th switch element S 1-S 6, commutation circuit 41 is by first to the 6th switch element S 1-S 6Conducting or the switching that ends running and with filtered DC input voitage V DCConversion, and output one exchanges demodulating voltage V between one first output terminals A and one second output B T
In the present embodiment, the first switch element S 1And second switch element S 2Series connection in regular turn electrically connects and constitutes first switching branches 411, and the first switch element S 1An end and the anode of the anode of flow directing device 8 and input filter circuit 40 electrically connect second switch element S 2An end and the negative terminal of the negative terminal of flow directing device 8 and input filter circuit 40 electrically connect.The 3rd switch element S 3, the 4th switch element S 4And the 5th switch element S 5Series connection in regular turn electrically connects and constitutes second switch branch road 412 with 411 electric connections in parallel of first switching branches and the 3rd switch element S 3An end and the anode of the anode of flow directing device 8 and input filter circuit 40 electrically connect the 5th switch element S 5An end then with the negative terminal of flow directing device 8 and and the negative terminal of input filter circuit 40 electrically connect.The 6th switch element S 6An end be electrically connected at the 3rd switch element S of second switch branch road 412 3And the 4th switch element S 4Between, the other end then is electrically connected at the first switch element S of first switching branches 411 1And second switch element S 2Between, and electrically connect with first output terminals A.
In certain embodiments, first to the 6th switch element S 1-S 6Can be but be not limited to that (Metal-Oxide-SemiConduCtor Field-EffeCt Transistor MOSFET) constitutes, and first to the 6th switch element S by metal-oxide half field effect transistor 1-S 6Each have corresponding body diode (body diode), as shown in Figure 4 first to hexasomic diode D 1-D 6, the first body diode D wherein 1And the second body diode D 2Conducting direction be by second switch element S 2To the first switch element S 1Direction, the 3rd body diode D 3, limbs diode D 4And five body constituents diode D 5Conducting direction be by the 5th switch element S 5To the first switch element S 1Direction, hexasomic diode D 6Conducting direction be by the direction of first switching branches 411 to second switch branch road 412.
The control unit 43 and first to the 6th switch element S 1-S 6Control end electrically connect, it produces first to the 6th control signal V of pulse width modulation form C1～V C6Control first to the 6th switch element S respectively 1-S 6Conducting or end.
Output filter circuit 42 electrically connects with first output terminals A and the second output B of commutation circuit 41, and electrically connects with AC load 9, exchanges demodulating voltage V in order to receive T, and filtering exchanges demodulating voltage V TThe high frequency composition, with output AC output voltage V o to AC load 9.In present embodiment, output filter circuit 4 is by one first inductance L 1, one second inductance L 2And one second capacitor C 2Constitute first inductance L wherein 1An end and first output terminals A electrically connect second inductance L 2An end and the second output B electrically connect second capacitor C 2With first inductance L 1, second inductance L 2And AC load 9 electrically connects.
Below the manner of execution of dc-ac conversion circuit 4 of the present invention will be described exemplarily.See also Fig. 5 A and Fig. 5 B, and cooperate Fig. 4, wherein the sequential schematic diagram of Fig. 5 A and Fig. 5 B voltage that is respectively Fig. 4 and control signal and exchange the oscillogram of demodulating voltage.Shown in Fig. 4, Fig. 5 A and Fig. 5 B, when at positive half cycle, for example at 0～very first time T 1Between, the first control signal V C1And the 5th control signal V C5Mode with pulse width modulation changes, i.e. the mutual variation of forbidden energy level (disabled) and activation level (eanbled) is so the first switch element S 1And the 5th switch element S 5Simultaneously and carry out conducting constantly or by switching, in addition, the second control signal V C2, the 3rd control signal V C3And the 4th control signal V C4Then continue to be maintained the forbidden energy level, so second switch element S 2, the 3rd switch element S 3With the 4th switch element S 4Be cut-off state, moreover, the 6th control signal V C6Then continue to be maintained the activation level, so the 6th switch element S 6Be conducting state.
Therefore, when in positive half cycle and the first switch element S 1And the 5th switch element S 5During for conducting state, the electric current that flow directing device 8 the is exported first switch element S that flows through in regular turn 1, first inductance L 1, second capacitor C 2, second inductance L 2And the 5th switch element S 5So, conversion that the electric energy of the direct current form that flow directing device 8 is exported just can be by dc-ac conversion circuit 4 and filtering and be sent to AC load 9, first inductance L simultaneously with form of communication 1And second inductance L 2Carry out energy storage, when at positive half cycle and the first switch element S 1And the 5th switch element S 5When switching to cut-off state, because the electric current continuation property of inductance, so first inductance L 1And second inductance L 2It is the 4th switch element S of cut-off state that stored energy just can be flowed through in regular turn in the mode of electric current 4Limbs diode D 4And be the 6th switch element S of conducting state 6, old friend's current load 9 also receives the electric energy that flow directing device 8 is exported sustainably.
When at negative half period, for example at very first time T 1～the second time T 2Between, the second control signal V C2And the 3rd control signal V C3Mode with pulse width modulation changes, i.e. so the mutual variation of forbidden energy level and activation level is second switch element S 2And the 3rd switch element S 3Simultaneously and carry out conducting constantly or by switching, in addition, the first control signal V C1, the 5th control signal V C5And the 6th control signal V C6Then change by continuing to maintain the forbidden energy level, so the first switch element S 1, the 5th switch element S 5With the 6th switch element S 6Be cut-off state, moreover, the 4th control signal V C4Then change by continuing to maintain the activation level, so the 4th switch element S 4Be conducting state.
Therefore, when at negative half period and second switch element S 2And the 3rd switch element S 3During for conducting state, the electric current that flow directing device 8 is exported the 3rd switch element S that flows through in regular turn 3, the 4th switch element S 4, second inductance L 2, second capacitor C 2, first inductance L 1And second switch element S 2So, conversion that the electric energy of the direct current form that flow directing device 8 is exported just can be by dc-ac conversion circuit 4 and filtering and be sent to AC load 9, first inductance L simultaneously with form of communication 1And second inductance L 2Carry out energy storage, when in negative half period and second switch element S 2And the 3rd switch element S 3When switching to cut-off state, because the electric current continuation property of inductance, so first inductance L 1And second inductance L 2It is the 6th switch element S of cut-off state that stored energy just can be flowed through in regular turn in the mode of electric current 6Hexasomic diode D 6And the 4th switch element S of conducting state 4, old friend's current load 9 also receives the electric energy that flow directing device 8 is exported sustainably.
Please consult Fig. 5 B again, by the 4th switch element S 4And the 6th switch element S 6Setting, make the interchange demodulating voltage V that commutation circuit 41 is exported TBe when positive half cycle 0 on the occasion of a specific voltage value Vr between do change, at negative half period then is to do change 0 between the specific voltage value Vr of negative value, so it is similar that the full-bridge type commutation circuit 11 of commutation circuit 41 actual manner of execution and existing dc-ac conversion circuit 1 shown in Figure 1 adopts unipolar switching working mode to operate, so switch cost of those switch elements of reduced commutation circuit 41 inside of dc-ac conversion circuit 4 of the present invention, and then lifting efficient, in addition, as seen from the figure, first output terminals A of commutation circuit 41 and the second output B be respectively for the relative voltage of a specified point of dc-ac conversion circuit 4 internal circuits, for example for the parasitic capacitance C that is produced with flow directing device 8 P(as shown in Figure 4) the first relative voltage V of the common contact N of Dian Xinglianjieing ANAnd the second relative voltage V BN, both the in office one addition mean value that switches time point is to keep a fixed value, so parasitic capacitance C POn can't produce tangible voltage variety, thus, just can reduce the generation of leakage current, and then the risk of harm reduction human body and equipment.
In the above-described embodiments, the first control signal V C1, the second control signal V C2, the 3rd control signal V C3And the 5th control signal V C5Be the pulse width modulation signal of high frequency, the 4th control signal V C4And the 6th control signal V C6It then is the pulse width modulation signal of low frequency.
Below the circuit structure of control unit 43 that schematic illustration is shown in Figure 4.See also Fig. 6 A and Fig. 6 B, wherein Fig. 6 A is the electrical block diagram of control unit shown in Figure 4, Fig. 6 B is the sequential schematic diagram of voltage shown in Fig. 6 A and control signal, control unit 43 comprises one first comparator 430, one second comparator 431, one the 3rd comparator 432 and a not gate 433, and wherein the positive input terminal of first comparator 430 receives a first string ripple signal V 1, the negative input end of first comparator 430 is ground connection then, and the output of first comparator 430 electrically connects the 6th switch element S 6Control end and export the 6th control signal V C6, the positive input terminal of second comparator 431 receives first string ripple signal V 1, the negative input end of second comparator 431 then receives a triangular signal V TRI, the output of second comparator 431 electrically connects the first switch element S 1Control end and the 5th switch element S 5Control end and export the first control signal V C1And the 5th control signal V C5, the positive input terminal of the 3rd comparator 432 receives one second string ripple signal V 2, this first string ripple signal V 1And the second string ripple signal V 2Phase difference be 180 degree, the negative input end of the 3rd comparator 432 receives triangular signal V TRI, the output of the 3rd comparator 432 then electrically connects second switch element S 2Control end and the 3rd switch element S 3Control end and export the second control signal V C2And the 3rd control signal V C3, the input of not gate 433 is electrically connected at the output of first comparator 430, and the output of not gate 433 is electrically connected at the 4th switch element S 4Control end, not gate 433 is with the 6th control signal V C6Oppositely, to export the 4th control signal V C4
Certainly, control unit 43 is not limited to aforesaid circuit structure, in some embodiment, shown in Fig. 7 A and Fig. 7 B, control unit 43 also can comprise one first comparator 730, one second comparator 731, one the 3rd comparator 732, a not gate 733, one first with door 734, second with door 735 and rectifying device 736, wherein rectifying device 736 receptions one string ripple signal V 3, and it is rectified into a rectification string ripple signal V 4
The positive input terminal of first comparator 730 and rectifying device 736 electrically connect and reception rectification string ripple signal V 4, the negative input end of first comparator 730 then receives triangular signal V TRI, the output of first comparator 730 be electrically connected at first with door 734 first input end.The positive input terminal of second comparator 731 receives string ripple signal V 3, the negative input end ground connection of second comparator 731, the output of second comparator 731 and the 6th switch element S 6Control end electrically connect and export the 6th control signal V C6The positive input terminal of the 3rd comparator 732 and rectifying device 736 electrically connect and reception rectification string ripple signal V 4, the negative input end of the 3rd comparator 732 receives triangular signal V TRI, the output of the 3rd comparator 732 be electrically connected at second with a door first input end of 735.
The input of not gate 733 is electrically connected at the output of second comparator 731 and receives the 6th control signal V C6, the output of not gate 733 electrically connects the 4th switch element S 4, not gate 733 is with the 6th control signal V C6Oppositely, to export the 4th control signal V in the output of not gate 733 C4First is electrically connected at the output of second comparator 731 and receives the 6th control signal V with door 734 second input C6, first electrically connects the first switch element S with door 734 output 1Control end and the 5th switch element S 5Control end and export the first control signal V C1And the 5th control signal V C5, second electrically connects with the output of door 735 the second input NAND gate 733 and receives the 4th control signal V C4, second electrically connects second switch element S with door 735 output 2Control end and the 3rd switch element S 3Control end and export the second control signal V C2And the 3rd control signal V C3
In sum, dc-ac conversion circuit of the present invention is by being provided with the 4th switch element and the 6th switch element, make the switch cost of those switch elements of commutation circuit inside to reduce, and then lifting efficient, simultaneously, since can't produce tangible voltage variety on the formed over the ground parasitic capacitance of flow directing device, the generation of leakage current can be reduced, and then the risk of harm reduction human body and equipment.
The present invention must be thought and is to modify right neither taking off as Protector that attached claim is desired as all by the personage Ren Shi craftsman who knows this technology.

Claims (15)

1. a dc-ac conversion circuit is characterized in that, comprising: one switches circuit, and framework is in receiving direct current energy, and changes, and output one exchanges demodulating voltage between one first output and one second output, and comprises:
One first switching branches comprises one first switch element and a second switch element that series connection in regular turn electrically connects, electrically connects this first output between this first switch element and this second switch element; And
One second switch branch road, with the electric connection in parallel of this first switching branches, and comprise one the 3rd switch element, one the 4th switch element and one the 5th switch element that series connection in regular turn electrically connects, electrically connect this second output between the 4th switch element and the 5th switch element; And
One the 6th switch element, one end are electrically connected between the 3rd switch element and the 4th switch element, and the other end is electrically connected between this first switch element and this second switch element and with this first output and electrically connects;
Wherein, when positive half cycle, simultaneously and the constantly conducting or of this first switch element and the 5th switch element by switching, the 6th switch element is a conducting state, when negative half period, change by the simultaneously and constantly conducting or by switching, the 4th switch element is a conducting state of this second switch element and the 3rd switch element.
2. dc-ac conversion circuit according to claim 1, it is characterized in that, when positive half cycle, this second switch element, the 3rd switch element and the 4th switch element are cut-off state, when negative half period, this first switch element, the 5th switch element and the 6th switch element are cut-off state.
3. dc-ac conversion circuit according to claim 2, it is characterized in that, also have a control unit, electrically connect to the 6th switch element with this first switch element, framework is in controlling the action that this first switch element carries out conducting or ends to the 6th switch element respectively.
4. dc-ac conversion circuit according to claim 3 is characterized in that, this control unit comprises:
One first comparator, the positive input terminal of this first comparator receive a first string ripple signal, the negative input end ground connection of this first comparator, and the output of this first comparator electrically connects the control end of the 6th switch element;
One second comparator, the positive input terminal of this second comparator receives this first string ripple signal, the negative input end of this second comparator receives a triangular signal, and the output of this second comparator electrically connects the control end of this first switch element and the control end of the 5th switch element;
One the 3rd comparator, the positive input terminal of the 3rd comparator receives one second string ripple signal, the negative input end of the 3rd comparator receives this triangular signal, and the output of the 3rd comparator electrically connects the control end of this second switch element and the control end of the 3rd switch element; And
One not gate, the input of this not gate is electrically connected at the output of this first comparator, and the output of this not gate is electrically connected at the control end of the 4th switch element.
5. dc-ac conversion circuit according to claim 4 is characterized in that, the phase difference of this first string ripple signal and this second string ripple signal is 180 degree.
6. dc-ac conversion circuit according to claim 3 is characterized in that, this control unit comprises:
One rectifying device receives a string ripple signal, and is rectified into a rectification string ripple signal;
One first comparator, the positive input terminal of this first comparator electrically connects this rectifying device, and the negative input end of this first comparator receives a triangular signal;
One second comparator, the positive input terminal of this second comparator receive this string ripple signal, the negative input end ground connection of this second comparator, and the output of this second comparator electrically connects the control end of the 6th switch element;
One the 3rd comparator, the positive input terminal of the 3rd comparator electrically connects this rectifying device, and the negative input end of the 3rd comparator receives this triangular signal;
One not gate, the input of this not gate electrically connects the output of this second comparator, and the output of this not gate electrically connects the control end of the 4th switch element;
One first with the door, this first electrically connects the output of this first comparator with the first input end of door, this first electrically connects the output of this second comparator with second input of door, and this first electrically connects the control end of this first switch element and the control end of the 5th switch element with the output of door; And
One second with the door, this second electrically connects the output of this not gate with the first input end of door, this second electrically connects the output of the 3rd comparator with second input of door, and this second electrically connects the control end of this second switch element and the control end of the 3rd switch element with the output of door.
7. dc-ac conversion circuit according to claim 1, it is characterized in that this first switch element, this second switch element, the 3rd switch element, the 4th switch element, the 5th switch element and the 6th switch element operate in the mode of pulse width modulation.
8. dc-ac conversion circuit according to claim 1, it is characterized in that, this first switch element, this second switch element, the 3rd switch element and the 5th switch element carry out conducting in the mode of high frequency or by switching, the 4th switch element and the 6th switch element carry out conducting or end switching in the mode of low frequency.
9. dc-ac conversion circuit according to claim 1 is characterized in that, this dc-ac conversion circuit is a non-isolation type.
10. dc-ac conversion circuit according to claim 1 is characterized in that this dc-ac conversion circuit is applied to the sunlight grid-connected system.
11. dc-ac conversion circuit according to claim 1 is characterized in that, this first to the 6th switch element is made of metal-oxide half field effect transistor.
12. dc-ac conversion circuit according to claim 11, it is characterized in that, this first to the 6th switch element has a body diode separately, and the conducting direction of those body diodes that this second switch element and this first switch element the are had direction of this second switch element of serving as reasons to this first switch element, the 3rd switch element, the conducting direction of those body diodes that the 4th switch element and the 5th switch element are had is served as reasons the 5th switch element to the direction of this first switch element, the conducting direction of this body diode that the 6th switch element the is had direction of this first switching branches to this second switch branch road of serving as reasons.
13. dc-ac conversion circuit according to claim 1, it is characterized in that this of this commutation circuit first output maintains a fixed value to this second output of one first relative voltage of the altogether contact in this dc-ac conversion circuit and this commutation circuit to the addition mean value of one second relative voltage of this common contact.
14. dc-ac conversion circuit according to claim 1, it is characterized in that, this dc-ac conversion circuit also has an input filter circuit, electrically connect with this commutation circuit, framework is in receiving a direct current input voltage, and this DC input voitage carried out filtering, change to export filtered this DC input voitage to this commutation circuit.
15. dc-ac conversion circuit according to claim 1, it is characterized in that this dc-ac conversion circuit also has an output filter circuit, electrically connect with this commutation circuit, framework is somebody's turn to do the high frequency composition that exchanges demodulating voltage in filtering, to export an ac output voltage.
CN 201110190951 2011-07-08 2011-07-08 DC-AC conversion circuit Active CN102255537B (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013063844A1 (en) * 2011-11-03 2013-05-10 台州富凌电气有限公司 Highly efficient inverter
TWI474602B (en) * 2012-12-12 2015-02-21 Univ Nat Penghu Switching method of bidirectional converter

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050174817A1 (en) * 2004-02-09 2005-08-11 Heribert Schmidt DC/AC converter to convert direct electric voltage into alternating voltage or into alternating current
CN101882883A (en) * 2009-05-08 2010-11-10 盈正豫顺电子股份有限公司 Direct current/alternating current transformer

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050174817A1 (en) * 2004-02-09 2005-08-11 Heribert Schmidt DC/AC converter to convert direct electric voltage into alternating voltage or into alternating current
CN101882883A (en) * 2009-05-08 2010-11-10 盈正豫顺电子股份有限公司 Direct current/alternating current transformer

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013063844A1 (en) * 2011-11-03 2013-05-10 台州富凌电气有限公司 Highly efficient inverter
TWI474602B (en) * 2012-12-12 2015-02-21 Univ Nat Penghu Switching method of bidirectional converter

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