CN113992012B - Suspension capacitance type Boost circuit, inverter and grid-connected power generation system - Google Patents
Suspension capacitance type Boost circuit, inverter and grid-connected power generation system Download PDFInfo
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- CN113992012B CN113992012B CN202111444891.6A CN202111444891A CN113992012B CN 113992012 B CN113992012 B CN 113992012B CN 202111444891 A CN202111444891 A CN 202111444891A CN 113992012 B CN113992012 B CN 113992012B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Abstract
The application provides a suspension capacitance type Boost circuit, an inverter and a grid-connected power generation system, wherein corresponding first switch modules and second switch modules are respectively arranged on two sides of a suspension capacitor in a main topology of the suspension capacitance type Boost circuit; when the first end and the second end of each switch module are connected, the suspension capacitor is connected between a connection point of a branch circuit where the rectifier diode is positioned and a branch circuit where the output capacitor is positioned in the main topology and a connection point of two corresponding power tubes in the main topology, so that the suspension capacitor can be precharged; in addition, under the condition of active output of the main topology, each rectifying diode can automatically realize voltage equalizing. That is, the floating capacitor type Boost circuit can solve the problem of unbalanced voltage of the rectifier diode under the conditions of pre-charging and active output of the floating capacitor by using fewer devices, and the scheme is simple and effective and has high reliability.
Description
Technical Field
The application relates to the technical field of power electronics, in particular to a suspension capacitance type Boost circuit, an inverter and a grid-connected power generation system.
Background
In a 1500V photovoltaic system, a three-level technology is generally adopted, and for a string converter, a front-stage Boost circuit of the string converter generally adopts a symmetrical three-level Boost or suspension capacitance three-level Boost topology; compared with the symmetrical three-level Boost topology, the floating capacitance three-level Boost topology has the advantage of common input and output ground, so that the application of the floating capacitance three-level Boost topology is gradually increased.
At present, the difficulty of the application of the suspension capacitor type three-level Boost topology is the problem of unbalanced voltage of the rectifier diode under the conditions of pre-charging and active output of the suspension capacitor. For both problems, the current solutions require the addition of more and complex hardware circuitry.
Disclosure of Invention
In view of this, the present application provides a floating capacitor type Boost circuit, an inverter and a grid-connected power generation system, so as to reduce the complexity of hardware circuit that needs to be increased when the problems of unbalanced voltage of the rectifying diode under the active output condition and the precharge of the floating capacitor are solved.
In order to achieve the above object, the embodiment of the present application provides the following technical solutions:
the first aspect of the present application provides a floating capacitor type Boost circuit, wherein two sides of a floating capacitor in a main topology are respectively provided with a corresponding switch module: a first switch module and a second switch module; each switch module is provided with a first end, a second end and a third end respectively; wherein, the liquid crystal display device comprises a liquid crystal display device,
when each switch module is in a state that the first end and the second end are connected: the first end of the suspension capacitor is connected with a connection point of a branch where the rectifier diode is located and a branch where the output capacitor is located in the main topology through the corresponding first switch module; the second end of the suspension capacitor is connected with the connection point of the two corresponding output capacitors in the main topology through the corresponding second switch module;
when each switch module is in a state that the first end and the third end are connected: the first end of the suspension capacitor is connected with the connection point of the two corresponding rectifying diodes in the main topology through the corresponding first switch module; and the second end of the suspension capacitor is connected with the connection point of the two corresponding power tubes in the main topology through the corresponding second switch module.
Optionally, before the main topology is controlled to enter the working state, each switch module is controlled to switch itself from the state that the first end is connected with the second end to the state that the first end is connected with the third end.
Optionally, a current limiting resistor is further disposed between the second end of the second switch module and the connection point corresponding to the two output capacitors, and is used for limiting current impact caused when each switch module switches the connection state.
Optionally, each switch module is a single-pole double-throw switch, a fixed node of the single-pole double-throw switch is used as a first end of the corresponding switch module, a normally closed node of the single-pole double-throw switch is used as a second end of the corresponding switch module, and a normally open node of the single-pole double-throw switch is used as a third end of the corresponding switch module.
Optionally, each switch module includes two switch tubes;
one ends of the two switching tubes are connected and serve as first ends of corresponding switching modules;
the other ends of the two switching tubes are respectively used as a second end and a third end of the corresponding switching module.
Optionally, the capacitance value of the suspension capacitor is less than or equal to 10% of the total capacitance value of the output capacitor connected in parallel when the first end and the second end of the switch modules at two sides of the suspension capacitor are connected.
Optionally, when the main topology is an n+1 level output topology, the number of the suspension capacitors is n-1; n is an integer greater than 1.
Optionally, the master topology includes: the power supply comprises an input capacitor, an input inductor, n power tubes, n rectifying diodes, n output capacitors and n-1 suspension capacitors; wherein:
the input capacitor is arranged between two poles of the input end of the main topology;
the first end of the input inductor is connected with one pole of the input end of the main topology;
the second end of the input inductor is connected with the corresponding pole of the output end of the main topology through each rectifier diode in sequence, and is also connected with the other pole of the input end and the other pole of the output end of the main topology through each power tube in sequence;
each output capacitor is sequentially connected in series between two poles of the output end of the main topology;
and from the second end of the input inductor, a corresponding suspension capacitor is respectively arranged between the connecting point of two adjacent power tubes and the connecting point of two corresponding rectifying diodes.
Optionally, the input inductor and each rectifying diode are both arranged on an anode branch of the main topology, and the main topology is a common-negative topology; or alternatively, the process may be performed,
the input inductor and each rectifier diode are arranged on a negative electrode branch of the main topology, and the main topology is a common positive electrode topology.
The second aspect of the present application also provides an inverter comprising: the control module, and the DC/AC conversion circuit and at least one DC/DC conversion circuit controlled by the control module;
the output end of the DC/DC conversion circuit is connected in parallel with the direct current side of the DC/AC conversion circuit;
the DC/DC conversion circuit is a floating capacitance Boost circuit as described in any one of the preceding paragraphs.
Optionally, the control module includes: a first control unit that controls the DC/AC conversion circuit, and a second control unit that controls the corresponding DC/DC conversion circuit;
the first control unit is in communication with the second control unit.
The third aspect of the present application also provides a grid-connected power generation system, including: a DC/AC converter and at least one DC/DC converter;
the output end of the DC/DC converter is connected in parallel with the direct current side of the DC/AC converter;
the main circuit in the DC/DC converter is the floating capacitor Boost circuit in any one of the first paragraph;
the DC/AC converter is communicatively coupled to the DC/DC converter.
The application provides a suspension capacitance type Boost circuit, wherein two sides of a suspension capacitor in a main topology are respectively provided with a corresponding first switch module and a corresponding second switch module; when the first end and the second end of each switch module are connected, the suspension capacitor is connected between a connection point of a branch where the rectifier diode is located and a branch where the output capacitor is located in the main topology and a connection point of two corresponding power tubes in the main topology, so that the precharge of the suspension capacitor can be realized by the input voltage of the main topology through the branch where the rectifier diode is located; in addition, under the condition of active output of the main topology, as no passage exists between the connection point of each rectifier diode and the connection point of each power tube, each rectifier diode can automatically realize voltage equalizing, and the problem of unbalanced voltage of the rectifier diode is avoided. In addition, when the first end and the third end of each switch module are connected, the suspension capacitor can be switched to a normal position in the main topology. Therefore, the floating capacitor type Boost circuit can solve the problem of unbalanced voltage of the rectifier diode under the conditions of pre-charging and active output of the floating capacitor by using fewer devices, and has simple and effective scheme and high reliability.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following description will briefly explain the embodiments or the drawings to be used in the description of the prior art, and it is obvious that the drawings in the following description are only embodiments of the present application, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
Fig. 1, fig. 2 and fig. 4 are schematic diagrams of three structures of a three-level floating capacitor type Boost circuit provided in the prior art, respectively;
FIG. 3 is a schematic diagram of the voltage division of a rectifier diode of a three-level floating capacitor type Boost circuit provided in the prior art under the condition of active output;
FIG. 5a is a schematic diagram of a three-level floating capacitor type Boost circuit according to an embodiment of the present application;
fig. 5b and fig. 5c are two circuit diagrams of a three-level floating capacitor type Boost circuit according to an embodiment of the present application;
FIG. 6 is a circuit diagram of a four-level floating capacitor type Boost circuit according to an embodiment of the present application;
FIG. 7 is a circuit diagram of an n+1 level floating capacitance Boost circuit according to an embodiment of the present application;
fig. 8 is a schematic structural diagram of an inverter according to an embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the present disclosure, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
Fig. 1 shows a suspended capacitor type three-level Boost circuit, which specifically includes: the power supply comprises an input capacitor Cin, an input inductor L, two power tubes T1 and T2, two rectifier diodes D1 and D2, two output capacitors C1 and C2 and a suspension capacitor Cf; wherein:
the input capacitor Cin is arranged between two poles of the input end of the circuit; the first end of the input inductor L is connected with the positive electrode of the input end of the circuit; the second end of the input inductor L is connected with the positive electrode of the circuit output end sequentially through rectifier diodes D1 and D2, and is also connected with the negative electrode of the circuit input end and the negative electrode of the circuit output end sequentially through power tubes T1 and T2; the output capacitors C1 and C2 are sequentially connected in series between two poles of the output end of the circuit; the floating capacitor Cf is provided between the connection point of the power transistors T1 and T2 and the connection point of the rectifier diodes D1 and D2.
Before the circuit works normally, since the power tubes T1 and T2 are not conducted, the floating capacitor Cf has no charging path, and automatic precharge cannot be realized; thus, the prior art typically precharges the floating capacitor Cf by adding an additional soft start auxiliary circuit, as shown in fig. 2; the soft start auxiliary circuit generally needs more circuit devices and has a complex circuit structure.
In addition, since the circuit has the function of boosting, the voltage of the output end of the circuit is necessarily higher than the voltage of the input end; under some conditions, the input voltage will be zero even if the input terminal is disconnected, for example, referring to fig. 3, since the voltages on the input capacitor Cin and the floating capacitor Cf are both 0V, the voltage born by the rectifying diode D2 will be the whole output voltage Uout, and the voltage born by the rectifying diode D1 is approximately equal to 0V, so the circuit still has the problem of unbalanced rectifying diode voltages under the active output condition. The prior art generally requires the addition of an additional clamping circuit to achieve the voltage clamping for the rectifier diode D2, as shown in fig. 4.
That is, in order to solve the problem of unbalanced voltage of the rectifying diode in the case of precharging and outputting the active voltage of the floating capacitor, the prior art needs to be implemented by separately providing corresponding devices, that is, the soft start auxiliary circuit in fig. 2 and the clamp circuit in fig. 4 need to be added at the same time, the circuit structure is complex, and the cost is increased.
Therefore, the application provides a floating capacitor type Boost circuit to solve the problem of unbalanced voltage of the rectifier diode under the condition of pre-charging and active output of the floating capacitor at the same time, and reduce the complexity of hardware circuits which need to be increased.
Fig. 5a shows a suspension capacitor type three-level Boost circuit provided in this embodiment, where the main topology specifically includes: the power supply comprises an input capacitor Cin, an input inductor L, two power tubes T1 and T2, two rectifier diodes D1 and D2, two output capacitors C1 and C2 and a suspension capacitor Cf; wherein:
the input capacitor Cin is arranged between two poles of the main topology input end; the first end of the input inductor L is connected with the positive electrode of the main topology input end; the second end of the input inductor L is connected with the positive electrode of the main topology output end sequentially through rectifier diodes D1 and D2, and is also connected with the negative electrode of the main topology input end and the negative electrode of the output end sequentially through power tubes T1 and T2; the output capacitors C1 and C2 are sequentially connected in series between two poles of the output end of the main topology.
Different from the prior art, two sides of the suspension capacitor Cf are respectively provided with two switch modules: a first switch module and a second switch module, as shown in fig. 5 a; each switch module is provided with a first end, a second end and a third end respectively; the first end of the first connecting rod can be selectively connected with the second end or the third end of the first connecting rod. Each switch module may be a single pole double throw switch (as shown in fig. 5 b) or two switch tubes (as shown in fig. 5 c) with one end connected.
Taking the single pole double throw switch shown in fig. 5b as an example, the fixed node thereof is taken as the first end of the corresponding switch module, the normally closed node thereof is taken as the second end of the corresponding switch module, and the normally open node thereof is taken as the third end of the corresponding switch module. As shown in fig. 5b, the two switch modules, namely a first single pole double throw switch S1 and a second single pole double throw switch S2; the first end of the floating capacitor Cf is connected with a connection point of the rectifying diode D2 and the output capacitor C1 through a fixed node and a normally closed node 1 of the first single-pole double-throw switch S1; the first end of the suspension capacitor Cf is also connected with the connection point of the rectifier diodes D1 and D2 through the fixed node and the normally open node 2 of the first single-pole double-throw switch S1; the second end of the floating capacitor Cf is connected with a connection point of the output capacitors C1 and C2 through a fixed node and a normally closed node 1 of a second single-pole double-throw switch S2; the second end of the floating capacitor Cf is also connected with the connection point of the power tubes T1 and T2 through the fixed node and the normally open node 2 of the second single pole double throw switch S2.
When the fixed nodes of the two single-pole double-throw switches are connected with the normally open node 2, the floating capacitor Cf is connected between the connection point of the power tubes T1 and T2 and the connection point of the rectifier diodes D1 and D2, and the main topology is equivalent to the structure shown in FIG. 1, so that the normal boosting function of the power tube can be realized. When the fixed node of the two single pole double throw switches is connected with the normally closed node 1, the floating capacitor Cf is connected in parallel with the output capacitor C1.
The circuit has the following two application cases:
(1) When the circuit is powered off completely, and voltage is applied to the input side, the circuit automatically charges the output capacitors C1 and C2, and simultaneously automatically precharges the floating capacitor Cf to half-bus voltage; when the parameter design of the floating capacitor Cf is proper, for example, the capacitance value of the floating capacitor Cf is less than or equal to 10% of the capacitance value of the output capacitor C1, the influence of the separated electric quantity on the output capacitors C1 and C2 is small, and the bias voltage of the floating capacitor Cf on the output capacitors C1 and C2 is negligible. When the circuit is ready to enter a working state, the two single-pole double-throw switches S1 and S2 are switched from the normally closed node 1 to the normally open node 2, so that the conversion of a topological structure is realized. In addition, in the switching process, since the voltage drop of the rectifying diode D2 in the forward conduction state is negligible, the nodes 1 and 2 of the first single-pole double-throw switch S1 are equipotential; the voltage at the connection point of the two power tubes T1 and T2 is also half bus voltage, so that the nodes 1 and 2 of the second single pole double throw switch S2 are also equipotential.
(2) When no power is applied to the input side and voltage is applied to the output side of the circuit, the voltage equalizing of the rectifying diodes D1 and D2 can be automatically realized and the whole output bus voltage Uout is borne due to the fact that the connection between the middle points of the rectifying diodes D1 and D2 and the middle points of the power tubes T1 and T2 is cut off. In addition, in the photovoltaic application scene, the output of the photovoltaic group string has electricity on the premise that the circuit works, so that the input side of the circuit is necessarily electrified, at the moment, the power tubes T1 and T2 bear input voltage, and the rectifier diodes D1 and D2 bear the difference Uout-Uin between the input voltage Uin and the output voltage Uout (the input voltage is smaller than the output voltage); before the circuit enters a working state, two single-pole double-throw switches S1 and S2 are switched from a normally closed node 1 to a normally open node 2, so that the conversion of a topological structure is realized; at this time, the voltage transformation of the nodes 1 and 2 of the two single-pole double-throw switches S1 and S2 is only half (Uout-Uin)/2 of the input and output voltage difference, the voltage variation is not large, and the device selection of the single-pole device switches S1 and S2 is facilitated.
According to the three-level floating capacitance type Boost circuit provided by the embodiment, the decoupling of the floating capacitance Cf and the main topology is realized by introducing the two single-pole double-throw switches S1 and S2 at the two ends of the floating capacitance Cf, and the pre-charging of the floating capacitance Cf is automatically realized in a default state. And only two single-pole double-throw switches are needed to be added, so that the charging problem of the suspended capacitor Cf of the three-level suspended capacitor type Boost circuit and the problem of uneven withstand voltage of the rectifier diode under the output active condition can be solved simultaneously.
Preferably, a current limiting resistor R is further disposed between the normally closed contact of the second single-pole double-throw switch S2 and the connection point of the output capacitors C1 and C2, for limiting current impact caused when the single-pole double-throw switches switch the connection state.
It should be noted that fig. 5a to fig. 5c only take a three-level floating capacitor Boost circuit as an example for illustration, but the scheme provided by the present application is not limited to a three-level circuit, and is also applicable to other multi-level circuits, such as five-level and seven-level circuits. Taking the example that the switch module comprises a single-pole double-throw switch, fig. 6 is a four-level floating capacitance type Boost circuit, fig. 7 is an n+1-level floating capacitance type Boost circuit, and n is an integer greater than 1; the main topologies comprise: input capacitance Cin, input inductance L, n power transistors (T1, T2, T3 as shown in fig. 6 and T1, T2, T3 … Tn as shown in fig. 7), n rectifier diodes (D1, D2, D3 as shown in fig. 6 and D1, D2, D3 … Dn as shown in fig. 7), n output capacitances (C1, C2, C3 as shown in fig. 6 and C1, C2, C3 … Cn as shown in fig. 7), and n-1 floating capacitances Cf; wherein:
the input capacitor Cin is arranged between two poles of the input end of the main topology; the first end of the input inductor L is connected with one pole of the input end of the main topology; the second end of the input inductor L is connected with the corresponding pole of the output end of the main topology through each rectifier diode in sequence, and is also connected with the other pole of the input end and the other pole of the output end of the main topology through each power tube in sequence; each output capacitor is sequentially connected in series between two poles of the output end of the main topology. Starting from the second end of the input inductor L, a corresponding suspension capacitor Cf is respectively arranged between the connecting point of two adjacent power tubes and the connecting point of two corresponding rectifying diodes; for example, a floating capacitor Cf is arranged between the connection point of the power tubes T1 and T2 and the connection point of the corresponding rectifying diodes D1 and D2; a floating capacitor Cf is also arranged between the junction of the power transistors T2 and T3 and the junction of the corresponding rectifier diodes D2 and D3.
When n=2, the suspension capacitance Boost circuit is a three-level circuit; when n=3, the floating capacitance Boost circuit is a four-level circuit; and so on.
No matter what value n is, two sides of each suspension capacitor Cf in the main topology are respectively provided with a corresponding single-pole double-throw switch: a first single pole double throw switch S1 and a second single pole double throw switch S2; for each floating capacitor Cf, there are:
the first end of the suspension capacitor Cf is connected with a connection point of a branch circuit where the rectifier diode is located and a branch circuit where the output capacitor is located in the main topology through a fixed node and a normally closed node 1 of a corresponding first single-pole double-throw switch S1; the first end of the floating capacitor Cf is also connected to the connection point of the two corresponding rectifier diodes in the main topology through the fixed node and the normally open node 2 of the corresponding first single pole double throw switch S1.
The second end of the floating capacitor Cf is connected with the connection point of the two corresponding output capacitors in the main topology through the fixed node and the normally closed node 1 of the corresponding second single-pole double-throw switch S2; the second end of the floating capacitor Cf is also connected with the connection point of the two corresponding power tubes in the main topology through the fixed node and the normally open node 2 of the corresponding second single-pole double-throw switch S2.
Optionally, the capacitance value of each suspension capacitor Cf is less than or equal to 10% of the total capacitance value of the output capacitors connected in parallel when the fixed nodes of the single-pole double-throw switches on the two sides of the suspension capacitor Cf are connected with the normally closed nodes. For example, from the second end of the input inductor L, the capacitance of the first floating capacitor Cf is less than or equal to 10% of the capacitance of the output capacitor C1, the capacitance of the second floating capacitor Cf is less than or equal to 10% of the total capacitance of the output capacitors C1 and C2, the capacitance of the third floating capacitor Cf is less than or equal to 10% of the total capacitance of the output capacitors C1, C2 and C3, and so on, and no further description is given.
It should be noted that, fig. 5a to fig. 7 each show a common negative electrode topology as an example, and the input inductance L and each rectifier diode are all disposed on the positive electrode branch of the main topology; in practical application, the dual topology, namely the common positive pole topology, the input inductance L and each rectifier diode are arranged on the negative pole branch of the main topology, and corresponding single-pole double-throw switches can be respectively arranged on two sides of each suspension capacitor Cf, so that the dual topology is within the protection scope of the application.
In the suspension capacitor type Boost circuit provided by the embodiment, corresponding first single-pole double-throw switch S1 and second single-pole double-throw switch S2 are respectively arranged on two sides of a suspension capacitor Cf in a main topology; when the fixed nodes of the single-pole double-throw switches are connected with the normally closed contacts, the floating capacitor Cf is connected between the connection point of the branch where the rectifier diode is positioned and the branch where the output capacitor is positioned in the main topology and the connection point of the corresponding two power tubes in the main topology, so that the precharge of the floating capacitor Cf can be realized by the input voltage of the main topology through the branch where the rectifier diode is positioned; in addition, under the condition of active output of the main topology, as no passage exists between the connection point of each rectifier diode and the connection point of each power tube, each rectifier diode can automatically realize voltage equalizing, and the problem of unbalanced voltage of the rectifier diode is avoided. In addition, when the fixed node of each single pole double throw switch is connected with the normally open contact, the floating capacitor Cf can also be switched to its normal position in the main topology. Therefore, the floating capacitor type Boost circuit can solve the problem of unbalanced voltage of the rectifier diode under the conditions of precharging and outputting the active power of the floating capacitor Cf by fewer devices, and the scheme is simple and effective and has high reliability.
In practical application, before the main topology of the suspension capacitor type Boost circuit is controlled to enter a working state, each single-pole double-throw switch is controlled to switch itself from a state that a fixed node is connected with a normally closed node 1 to a state that the fixed node is connected with a normally open node 2, so that the main topology can normally perform boosting work.
In addition, each switch module in the floating capacitor type Boost circuit is not limited to the single pole double throw switch shown in fig. 5b, 6 and 7, and may also include two switch tubes; one ends of the two switching tubes are connected and serve as first ends of corresponding switching modules; and the other ends of the two switching tubes are respectively used as a second end and a third end of the corresponding switching module. The implementation forms of the two switching tubes are not particularly limited, and are all within the protection scope of the application according to the application environment. The automatic control of the switch modules can be realized through the control modules in the equipment where the circuit is located.
Another embodiment of the present application also provides an inverter, as shown in fig. 8, including: the control module 10 and the DC/AC conversion circuit 22 controlled by the control module and at least one DC/DC conversion circuit 21 (a plurality of which are shown as examples in the figure); wherein the output end of each DC/DC conversion circuit 21 is connected in parallel to the DC side of the DC/AC conversion circuit 22; each DC/DC conversion circuit 21 is a floating capacitor Boost circuit as described in any of the embodiments above. The specific structure and the working principle of the suspension capacitance Boost circuit are just described in the above embodiments, and are not described in detail herein.
In practical applications, the control module 10 may include: a first control unit controlling the DC/AC conversion circuit, and a second control unit controlling the corresponding DC/DC conversion circuit;
the first control unit is communicatively connected to the second control unit. The inverter can be used as a string inverter of a grid-connected power generation system, and grid connection is performed after inversion of electric energy emitted by a photovoltaic string.
Another embodiment of the present application further provides a grid-connected power generation system, including: a DC/AC converter and at least one DC/DC converter; the output end of the DC/DC converter is connected in parallel with the direct current side of the DC/AC converter; the input ends of the DC/DC converters are respectively connected with corresponding photovoltaic group strings in the photovoltaic array; the main circuit in the DC/DC converter is a floating capacitor Boost circuit as in any one of the embodiments above; the specific structure and the working principle of the suspension capacitance Boost circuit are just described in the above embodiments, and are not described in detail herein. The DC/AC converter is in communication connection with the DC/DC converter, the DC/AC converter and the DC/DC converter can be respectively arranged at a long distance, and the function of the DC/AC converter can also be to invert the electric energy emitted by each photovoltaic group string and then grid-connect.
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for a system or system embodiment, since it is substantially similar to a method embodiment, the description is relatively simple, with reference to the description of the method embodiment being made in part. The systems and system embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present application without undue burden.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative elements and steps are described above generally in terms of functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
The features described in the various embodiments of the present disclosure may be interchanged or combined with one another in the description of the disclosed embodiments to enable those skilled in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (12)
1. The floating capacitor type Boost circuit is characterized in that corresponding switch modules are respectively arranged on two sides of a floating capacitor in a main topology: a first switch module and a second switch module; each switch module is provided with a first end, a second end and a third end respectively; wherein, the liquid crystal display device comprises a liquid crystal display device,
when each switch module is in a state that the first end and the second end are connected: the first end of the suspension capacitor is connected with a connection point of a branch where the rectifier diode is located and a branch where the output capacitor is located in the main topology through the corresponding first switch module; the second end of the suspension capacitor is connected with the connection point of the two corresponding output capacitors in the main topology through the corresponding second switch module;
when each switch module is in a state that the first end and the third end are connected: the first end of the suspension capacitor is connected with the connection point of the two corresponding rectifying diodes in the main topology through the corresponding first switch module; and the second end of the suspension capacitor is connected with the connection point of the two corresponding power tubes in the main topology through the corresponding second switch module.
2. The floating capacitor Boost circuit of claim 1, wherein each switch module is controlled to switch itself from a state in which the first terminal is connected to the second terminal to a state in which the first terminal is connected to the third terminal before the main topology is controlled to enter the active state.
3. The floating capacitor type Boost circuit of claim 1, wherein a current limiting resistor is further disposed between the second end of the second switch module and the connection point of the two output capacitors, for limiting current surge caused when each switch module switches the connection state.
4. The floating capacitor Boost circuit of claim 1, wherein each switch module is a single pole double throw switch, a fixed node of the single pole double throw switch is used as a first end of the corresponding switch module, a normally closed node of the single pole double throw switch is used as a second end of the corresponding switch module, and a normally open node of the single pole double throw switch is used as a third end of the corresponding switch module.
5. The floating capacitance Boost circuit of claim 1, wherein each switching module comprises two switching tubes;
one ends of the two switching tubes are connected and serve as first ends of corresponding switching modules;
the other ends of the two switching tubes are respectively used as a second end and a third end of the corresponding switching module.
6. The floating capacitor type Boost circuit of any one of claims 1 to 5, wherein the floating capacitor has a capacitance value of 10% or less of the total capacitance value of the output capacitor connected in parallel when the first and second ends of the two-sided switch modules are connected.
7. The floating capacitance Boost circuit according to any one of claims 1 to 5, wherein when the main topology is an n+1 level output topology, the number of floating capacitances is n-1; n is an integer greater than 1.
8. The floating capacitance Boost circuit of claim 7, wherein the main topology comprises: the power supply comprises an input capacitor, an input inductor, n power tubes, n rectifying diodes, n output capacitors and n-1 suspension capacitors; wherein:
the input capacitor is arranged between two poles of the input end of the main topology;
the first end of the input inductor is connected with one pole of the input end of the main topology;
the second end of the input inductor is connected with the corresponding pole of the output end of the main topology through each rectifier diode in sequence, and is also connected with the other pole of the input end and the other pole of the output end of the main topology through each power tube in sequence;
each output capacitor is sequentially connected in series between two poles of the output end of the main topology;
and from the second end of the input inductor, a corresponding suspension capacitor is respectively arranged between the connecting point of two adjacent power tubes and the connecting point of two corresponding rectifying diodes.
9. The floating capacitor Boost circuit of claim 8, wherein said input inductor and each of said rectifier diodes are disposed on a positive leg of said main topology, said main topology being a common negative topology; or alternatively, the process may be performed,
the input inductor and each rectifier diode are arranged on a negative electrode branch of the main topology, and the main topology is a common positive electrode topology.
10. An inverter, comprising: the control module, and the DC/AC conversion circuit and at least one DC/DC conversion circuit controlled by the control module;
the output end of the DC/DC conversion circuit is connected in parallel with the direct current side of the DC/AC conversion circuit;
the DC/DC conversion circuit is a floating capacitance Boost circuit according to any one of claims 1 to 9.
11. The inverter of claim 10, wherein the control module comprises: a first control unit that controls the DC/AC conversion circuit, and a second control unit that controls the corresponding DC/DC conversion circuit;
the first control unit is in communication with the second control unit.
12. A grid-tie power generation system, comprising: a DC/AC converter and at least one DC/DC converter;
the output end of the DC/DC converter is connected in parallel with the direct current side of the DC/AC converter;
the main circuit in the DC/DC converter is a floating capacitance Boost circuit according to any one of claims 1 to 9;
the DC/AC converter is communicatively coupled to the DC/DC converter.
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| CN108847769A (en) * | 2018-06-22 | 2018-11-20 | 阳光电源股份有限公司 | Three level BOOST devices of one kind and its control method |
| CN108900078A (en) * | 2018-08-03 | 2018-11-27 | 阳光电源股份有限公司 | A kind of striding capacitance type three-level converter and its control method |
| CN110165888A (en) * | 2019-06-11 | 2019-08-23 | 阳光电源股份有限公司 | Three level Boost circuits, multiple-channel output parallel system |
| CN212381111U (en) * | 2020-03-25 | 2021-01-19 | 上海正泰电源系统有限公司 | Three-level power conversion circuit capable of being precharged by flying capacitor |
| WO2021047154A1 (en) * | 2019-09-12 | 2021-03-18 | 科华恒盛股份有限公司 | Boost circuit, and apparatus and system thereof |
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| CN108258899B (en) * | 2017-12-29 | 2021-06-15 | 华为技术有限公司 | Boost power conversion circuit |
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| CN108847769A (en) * | 2018-06-22 | 2018-11-20 | 阳光电源股份有限公司 | Three level BOOST devices of one kind and its control method |
| CN108900078A (en) * | 2018-08-03 | 2018-11-27 | 阳光电源股份有限公司 | A kind of striding capacitance type three-level converter and its control method |
| CN110165888A (en) * | 2019-06-11 | 2019-08-23 | 阳光电源股份有限公司 | Three level Boost circuits, multiple-channel output parallel system |
| WO2020248583A1 (en) * | 2019-06-11 | 2020-12-17 | 阳光电源股份有限公司 | Three-level boost circuit and multi-output parallel system |
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