CN118412834A - DC-DC converter, photovoltaic inverter and direct current combiner box - Google Patents
DC-DC converter, photovoltaic inverter and direct current combiner box Download PDFInfo
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Abstract
The invention discloses a DC-DC converter, a photovoltaic inverter and a direct current combiner box. The DC-DC converter is used for being connected into a photovoltaic module with M photovoltaic units, and the output voltage of a branch circuit where each photovoltaic unit is located is the same; the photovoltaic module comprises a first type photovoltaic unit group and a second type photovoltaic unit group; each first type of photovoltaic unit group comprises a photovoltaic unit, and each second type of photovoltaic unit group comprises two photovoltaic units; the positive output ports of two photovoltaic units in each second type of photovoltaic unit group are connected in series with the same protection switch, and the negative output ports of two photovoltaic units in each second type of photovoltaic unit group are connected in series with the same protection switch. According to the DC-DC converter, through reasonably setting the wiring modes of the photovoltaic unit and the tripping direct current switch, the current of each pole of the switch is more balanced, and the maximum input current capacity of the DC-DC converter can be improved while the current utilization rate of the tripping switch is effectively improved under the condition that the switch selection is not changed.
Description
Technical Field
The invention belongs to the technical field of photovoltaic power generation, and particularly relates to a DC-DC converter, a photovoltaic inverter and a direct current combiner box.
Background
Currently, in order to boost the direct current ratio (the ratio of the power of a photovoltaic unit to the input power of a photovoltaic inverter) of a photovoltaic power generation system, at least two paths of photovoltaic units are generally connected to each path of MPPT circuit. Taking the example that one path of photovoltaic unit is short-circuited or the line where the photovoltaic unit is located is short-circuited, at this time, the short-circuited current is the sum of the output currents of the photovoltaic units of other paths connected, and when the number of the photovoltaic units of other paths connected is only 1, the short-circuited current can be tolerated by the photovoltaic units and the line due to smaller short-circuited current. However, when the number of photovoltaic cells of other paths connected is 2 or more, the short-circuit current is large, and in order to protect the photovoltaic cells and the lines, fuses may be connected in series at the positive output terminal or the negative output terminal of the photovoltaic cells, and the photovoltaic cells and the lines may be protected by blowing the fuses. However, since the fusing current of the fuse is generally higher, and the output current of each path of photovoltaic unit is lower, the sum of the short-circuit currents of the multiple paths of photovoltaic units may be difficult to reach the fusing current of the fuse, so that the fuse consumes a long time, the fuse cannot effectively protect the photovoltaic units and the lines, and the failure rate of the fuse is relatively higher, and the reliability is low.
In order to solve the problem, a remote trip switch is generally used for breaking fault current to realize protection. However, the current of each stage of the trip switch is not balanced, and excessive current of a single pole may occur, resulting in uneven heating, limiting further expansion of the system capacity, and thus limiting the maximum input current capability of the DC-DC converter.
Disclosure of Invention
Aiming at the technical problems, the invention aims to provide an improved DC-DC converter, a photovoltaic inverter and a direct current combiner box.
In order to achieve the above purpose, the invention adopts the following technical scheme:
A DC-DC converter for accessing a photovoltaic module having M photovoltaic units, each of the photovoltaic units comprising one or more photovoltaic modules;
The DC-DC converter comprises a DC-DC circuit, a direct current bus and a plurality of protection switches, wherein the direct current bus is connected with the input end of the DC-DC circuit;
The photovoltaic units are connected to the direct current buses through the protection switches, and each protection switch is used for disconnecting the corresponding photovoltaic unit from the direct current buses when the reverse current of the connected photovoltaic unit is larger than a first current value or exceeds a first current value;
m is a positive integer greater than or equal to 5, the photovoltaic module comprises a first type of photovoltaic unit group and a second type of photovoltaic unit group, the number of the first type of photovoltaic unit group is N, the number of the second type of photovoltaic unit group is K, wherein N is a positive integer and K is a positive integer andEach first type of photovoltaic unit group comprises one photovoltaic unit, and each second type of photovoltaic unit group comprises two photovoltaic units;
Positive output ports of two photovoltaic units in each second type of photovoltaic unit group are connected in series with the same protection switch, and negative output ports of two photovoltaic units in each second type of photovoltaic unit group are connected in series with the same protection switch;
the positive output port of the photovoltaic unit in the first type photovoltaic unit group and the positive output port of the photovoltaic unit in one of the second type photovoltaic unit groups are connected in series with the same protection switch; and the negative output port of the photovoltaic unit in the second type photovoltaic unit group and the negative output port of the photovoltaic unit in the other second type photovoltaic unit group are connected in series with the same protection switch.
Preferably, when N is a positive integer greater than or equal to 2, the protection switches connected in series with the positive output ports of the photovoltaic units in the different first-type photovoltaic unit groups are different, and the protection switches connected in series with the negative output ports of the photovoltaic units in the different first-type photovoltaic unit groups are different.
Preferably, the number of the protection switches is P,
Preferably, each of the protection switches corresponds to one pole number of a dc isolating switch, and the dc isolating switch includes a handle and P poles.
Further, when m=5, p=4, n=1, k=2, the negative output ports of the two photovoltaic units in the first second type photovoltaic unit group are connected in series to the first protection switch, and the positive output ports of the two photovoltaic units in the first second type photovoltaic unit group are connected in series to the second protection switch;
negative output ports of two photovoltaic units in the second type of photovoltaic unit group are connected to a third protection switch in series, and positive output ports of two photovoltaic units in the second type of photovoltaic unit group are connected to a fourth protection switch in series;
the positive output ports of the photovoltaic units in the first type of photovoltaic unit group are connected in series to the second protection switch, and the negative output ports of the photovoltaic units in the first type of photovoltaic unit group are connected in series to the third protection switch;
The distance between the first protection switch and the handle is smaller than that between the second protection switch and the third protection switch, and the distance between the third protection switch and the handle is smaller than that between the third protection switch and the fourth protection switch.
Further, when m=5, p=4, n=1, k=2, positive output ports of two photovoltaic units in the first second type photovoltaic unit group are connected in series to the first protection switch, and negative output ports of two photovoltaic units in the first second type photovoltaic unit group are connected in series to the second protection switch;
Positive output ports of two photovoltaic units in the second type of photovoltaic unit group are connected to a third protection switch in series, and negative output ports of two photovoltaic units in the second type of photovoltaic unit group are connected to a fourth protection switch in series;
The positive output ports of the photovoltaic units in the first type of photovoltaic unit group are connected to the first protection switch in series, and the negative output ports of the photovoltaic units in the first type of photovoltaic unit group are connected to the fourth protection switch in series;
The distance between the first protection switch and the handle is smaller than that between the second protection switch and the third protection switch, and the distance between the third protection switch and the handle is smaller than that between the third protection switch and the fourth protection switch.
Preferably, a plurality of the DC-DC converters and the DC-AC converter form an inverter;
the positive output ports of the DC-DC converters are connected to the positive input ports of the DC-AC converters in parallel, and the negative output ports of the DC-DC converters are connected to the negative input ports of the DC-AC converters in parallel.
Preferably, a plurality of the DC-DC converters form a direct current combiner box; the positive output ports of the DC-DC converters are connected in parallel to form a positive output port of the direct current combiner box; and the negative output ports of the DC-DC converters are connected in parallel to form the negative output port of the direct current combiner box.
A photovoltaic inverter comprising a DC-AC converter, the photovoltaic inverter further comprising a DC-DC converter as described above; the positive output ports of the DC-DC converters are connected to the positive input ports of the DC-AC converters in parallel, and the negative output ports of the DC-DC converters are connected to the negative input ports of the DC-AC converters in parallel.
A direct current combiner box comprises a plurality of paths of DC-DC converters as described above; the multiple paths of DC-DC converters are used for being connected into a photovoltaic module; the positive output ports of the DC-DC converters are connected in parallel to form a positive output port of the direct current combiner box; and the negative output ports of the DC-DC converters are connected in parallel to form the negative output port of the direct current combiner box.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:
According to the DC-DC converter, through reasonably setting the wiring modes of the photovoltaic unit and the tripping direct current switch, the current of each pole of the switch is more balanced, the current utilization rate of the tripping switch is effectively improved under the condition that the switch selection is not changed, the maximum input current capacity of the DC-DC converter can be improved, and the system capacity is conveniently expanded.
In a further preferred scheme, the positions of the protection switches with different distances from the handle are reasonably arranged, so that when the fault protection switch is disconnected, the voltage difference of the adjacent protection switches is reduced, and the problem of high voltage resistance between the two adjacent protection switches is solved.
Drawings
In order to more clearly illustrate the technical solutions of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a conventional DC-DC converter;
FIG. 2 is a schematic diagram of a DC-DC converter according to an embodiment of the present invention;
FIG. 3 is a schematic diagram showing the voltage distribution of the PV3 of FIG. 2 after the inversion;
FIG. 4 is a schematic diagram of another embodiment of a DC-DC converter according to the present invention;
FIG. 5 is a schematic diagram showing the voltage distribution of the PV3 of FIG. 4 after reversing the connection;
FIG. 6 is a schematic diagram of another embodiment of a DC-DC converter according to the present invention;
FIG. 7 is a schematic diagram showing the voltage distribution of the PV3 of FIG. 6 after reversing the connection;
FIG. 8 is a schematic diagram of another embodiment of a DC-DC converter according to the present invention;
FIG. 9 is a schematic diagram showing the voltage distribution of the PV3 of FIG. 8 after reversing the connection;
fig. 10 is a schematic diagram of a photovoltaic inverter according to an embodiment of the present invention;
FIG. 11 is a schematic diagram of a DC combiner box according to an embodiment of the present invention;
the photovoltaic module comprises a photovoltaic module and a power supply, wherein 1 is a photovoltaic module; 2. a DC-DC converter; 3. a photovoltaic unit; 4. a photovoltaic module; 5. a protection switch; 6. a DC-DC circuit; 7. a first type of photovoltaic cell group; 8. a second type of photovoltaic cell group; 9. a DC-AC converter; 10. a photovoltaic inverter; 11. a direct current combiner box.
Detailed Description
In order to solve the problem that the failure rate of the fuse is relatively high, a remote tripping switch is generally used for breaking fault current. Fig. 1 is a schematic diagram of a conventional DC-DC converter, in which S1'-S4' are each a pole number of a DC isolating switch, and PV1'-PV5' are each photovoltaic units, and once a short circuit or reverse connection of a certain PV is found, a control system sends a trip command to disconnect the corresponding switch (S1 '-S4'). However, in this connection mode, the current of each pole on S1'-S4' is not balanced, and the current of a single pole is too large, which limits further expansion of the system capacity.
Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art. The description of these embodiments is provided to assist understanding of the present invention, but is not intended to limit the present invention. In addition, technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
In this embodiment, the electrical parameters of the individual photovoltaic modules are not particularly limited, and may be set by those skilled in the art according to actual needs. In this embodiment, the output voltages of the multiple photovoltaic units connected to the same DC-DC converter are the same.
The following description will take a DC-DC converter as an example:
As shown in fig. 2 to 9, the DC-DC converter is used for connecting to a photovoltaic module 1 having M photovoltaic units 3, each photovoltaic unit 3 includes one or more photovoltaic modules 4 (specifically referring to PV1-PV5 in fig. 2), and in this embodiment, each photovoltaic unit 3 includes one photovoltaic module 4 is specifically described as an example. The DC-DC converter 2 comprises a plurality of protection switches 5, a direct current bus and a DC-DC circuit 6. The direct current bus is connected with the input end of the DC-DC circuit 6, and the output end of the DC-DC circuit 6 is the output end of the DC-DC converter 2. The photovoltaic units 3 are connected to the direct current buses through protection switches 5, and each protection switch 5 is used for disconnecting the corresponding photovoltaic unit from the direct current buses when the reverse current of the connected photovoltaic unit 3 is larger than a first current value (the first current value specifically refers to a preset safe current value) or the current of the circuit is over-current. The DC-DC circuit 201 may be specifically a Boost (Boost) circuit, a Buck (Buck) circuit, or a Buck-Boost (Buck-Boost) circuit.
Specifically, M is a positive integer of 5 or more. The photovoltaic module 1 comprises a first type of photovoltaic cell group 7 and a second type of photovoltaic cell group 8. The number of the first type photovoltaic cell groups 7 is N, and the number of the second type photovoltaic cell groups 8 is K. Wherein N is a positive integer and satisfiesK is a positive integer and satisfiesEach photovoltaic cell group 7 of the first type comprises one photovoltaic cell 3 and each photovoltaic cell group 8 of the second type comprises two photovoltaic cells 3, so that m=n+2k.
The positive output ports of the two photovoltaic units 3 in each second type of photovoltaic unit group 8 are connected in series with the same protection switch 5, and the negative output ports of the two photovoltaic units 3 in each second type of photovoltaic unit group 8 are connected in series with the same protection switch 5. Taking fig. 2 as an example, PV1 and PV2 belong to the same photovoltaic module 4 in the photovoltaic unit 3 in the second type of photovoltaic unit group 8, positive output ports of PV1 and PV2 are connected in series with the same protection switch S1, and negative output ports of PV1 and PV2 are connected in series with the same protection switch S2. The PV4 and the PV5 belong to the other second type of photovoltaic unit group 8, positive output ports of the PV4 and the PV5 in the photovoltaic units 3 are connected in series with the same protection switch S3, and negative output ports of the PV4 and the PV5 are connected in series with the same protection switch S4.
The positive output port of the photovoltaic unit 3 in the first type of photovoltaic unit group 7 and the positive output port of the photovoltaic unit in one of the second type of photovoltaic unit groups are connected in series with the same protection switch 5, and the negative output port of the photovoltaic unit 3 in the second type of photovoltaic unit group 7 and the negative output port of the photovoltaic unit 3 in the other second type of photovoltaic unit group 7 are connected in series with the same protection switch 5. Taking fig. 2 as an example, PV3 belongs to a photovoltaic module 4 in a photovoltaic unit 3 in a first type of photovoltaic unit group 7, a positive output port of PV3 and positive output ports of PV1 and PV2 are connected in series with the same protection switch S1, and a negative output port of PV3 and negative output ports of PV4 and PV5 are connected in series with the same protection switch S4.
When N is a positive integer greater than or equal to 2, the protection switches 5 connected in series with the positive output ports of the photovoltaic units 3 in the different first-type photovoltaic unit groups 7 are different, and the protection switches 5 connected in series with the negative output ports of the photovoltaic units 3 in the different first-type photovoltaic unit groups 7 are different. Taking fig. 6 as an example, PV3 and PV6 belong to different first-class photovoltaic unit groups 7, where the protection switch connected in series with the positive output port of PV3 is S1, the protection switch connected in series with the positive output port of PV6 is S3, the protection switch connected in series with the negative output port of PV3 is S4, and the protection switch connected in series with the negative output port of PV6 is S6.
The number of the protection switches 5 is P,I.e. p=kx2. Each protection switch 5 corresponds to one pole number of a direct current isolating switch, the direct current isolating switch comprises a handle and P poles, and the P protection switches 5 are controlled by the handle. As shown in fig. 2, when m=5, p=4, n=1, k=2. The positive output ports of the two photovoltaic units 3 (i.e. PV1 and PV 2) in the first second type of photovoltaic unit group 8 are connected in series to the first protection switch S1, and the negative output ports of the two photovoltaic units 3 in the first second type of photovoltaic unit group 8 are connected in series to the second protection switch S2. The positive output ports of the two photovoltaic units 3 (i.e. PV4 and PV 5) in the second type of photovoltaic unit group 8 are connected in series to the third protection switch S3, and the negative output ports of the two photovoltaic units 3 in the second type of photovoltaic unit group 8 are connected in series to the fourth protection switch S4. The positive output ports of the photovoltaic units 3 (i.e. PV 3) in the first type of photovoltaic unit group 7 are connected in series to the first protection switch S1, and the negative output ports of the photovoltaic units 3 in the first type of photovoltaic unit group 7 are connected in series to the fourth protection switch S4. The distance between the first protection switch S1 and the handle is smaller than that between the second protection switch S2, the distance between the second protection switch S2 and the handle is smaller than that between the third protection switch S3, and the distance between the third protection switch S3 and the handle is smaller than that between the third protection switch S4 and the handle. The handle is specifically an electric control handle, and a control signal is sent to a coil in the handle through the controller, so that the coil triggers a component for tripping the switch, and the control of the tripping switch is realized. In other embodiments, the tripping of the switch may also be controlled manually directly by the handle. Furthermore, in the actual application process, the protection switch close to the handle is easy to trip.
As shown In fig. 2, the operating current of each PV is In, and the total current handled by the DC-DC circuit 6 is 5×in. Different from the existing wiring mode, the current of each switch is 2 times In or 3 times In respectively, so that the current flowing on the protection switch is effectively reduced, and the current is more uniformly distributed. Wherein the anodes of PV1, PV2 and PV3 are connected together to S1, the cathodes of PV1 and PV2 are connected together to S2, the anodes of PV4 and PV5 are connected together to S3, and the cathodes of PV3, PV4 and PV5 are connected together to S4. Thus, the current flowing In S1 is 3 times the PV current (3×in), the current flowing In S2 is 2 times the PV current (2×in), the current flowing In S3 is (2×in), and the current flowing In S4 is 3 times the PV current (3×in). When the photovoltaic modules 4 in one path of photovoltaic units 3 in all the photovoltaic units 3 have short circuit or reverse connection faults, the system detects the faults, and the protection switch can be controlled to be disconnected in time. At this time, if the shorted or reversely connected photovoltaic module is one of PV1, PV2, PV4 and PV5, then there is one PV still forming a loop current with it, but since there are only two PV strings, only one PV short circuit current can be formed, there is no risk of damage. If the shorted or reversed photovoltaic module is PV3, the short circuit path is cut off, and no current is generated on all the photovoltaic strings, which is also safe.
Fig. 3 shows a schematic diagram when PV3 is reversed, and the relative potentials on the left side of each switch can be seen. Let the negative electrodes of PV1 and PV2 be at 0 level (0×v), i.e., the potential on the left side of S2 be 0V; the anodes of PV1 and PV2 are then 1 times the photovoltaic voltage (1×v), i.e. the potential on the left side of S1 is 1×v; the positive electrode of the PV3 is overlapped with a photovoltaic voltage of 2 XV on the positive electrodes of the PV1 and the PV2, namely the potential at the left side of the S4 is 2 XV; the positive electrodes of PV4 and PV5 are superimposed with a doubling of the photovoltaic voltage of 3×v on the positive electrode of PV3, i.e. the potential on the left side of S3 is 3×v. If S2 and S3 are adjacent, the voltage difference is large in the face of 3 XV withstand voltage.
Preferably, as shown with reference to fig. 4, when m=5, p=4, n=1, k=2. The negative output ports of the two photovoltaic units 3 (i.e. PV1 and PV 2) in the first second type of photovoltaic unit group 8 are connected in series to the first protection switch S1, and the positive output ports of the two photovoltaic units 3 in the first second type of photovoltaic unit group 8 are connected in series to the second protection switch S2. The negative output ports of the two photovoltaic units 3 (i.e. PV4 and PV 5) in the second type of photovoltaic unit group 8 are connected in series to the third protection switch S3, and the positive output ports of the two photovoltaic units 3 in the second type of photovoltaic unit group 8 are connected in series to the fourth protection switch S4. The positive output ports of the photovoltaic units 3 in the first type of photovoltaic unit group 7 are connected in series to the second protection switch S2, and the negative output ports of the photovoltaic units 3 in the first type of photovoltaic unit group 7 are connected in series to the third protection switch S3. The distance between the first protection switch S1 and the handle is smaller than that between the second protection switch S2, the distance between the second protection switch S2 and the handle is smaller than that between the third protection switch S3, and the distance between the third protection switch S3 and the handle is smaller than that between the third protection switch S4 and the handle.
The difference between the wiring modes in fig. 4 and fig. 2 is that the connection sequence of the protection switches is changed, so that the withstand voltage of the adjacent switches is reduced after the PV3 is reversely connected. Fig. 5 shows the voltage distribution after PV3 firing. Let the negative electrodes of PV1 and PV2 be at 0 level (0×v), i.e., the potential on the left side of S1 is 0V; the anodes of PV1 and PV2 are then 1 times the photovoltaic voltage (1×v), i.e. the potential on the left side of S2 is 1×v; the positive electrode of the PV3 is overlapped with a photovoltaic voltage of 2 XV on the positive electrodes of the PV1 and the PV2, namely the potential at the left side of the S3 is 2 XV; the positive electrodes of PV4 and PV5 are superimposed with a doubling of the photovoltaic voltage of 3×v on the positive electrode of PV3, i.e. the potential on the left side of S4 is 3×v. As can be seen from fig. 5, the withstand voltage between two adjacent switches is 1 times of the photovoltaic voltage, so that the problem of high withstand voltage between two adjacent protection switches is solved.
Fig. 6 to 9 show two connection modes when m=8. The wiring mode corresponding to fig. 8 is better than that corresponding to fig. 6, because the voltage difference between two adjacent protection switches is smaller after the PV3 in fig. 8 is reversely connected (i.e. fig. 9). Through further optimizing the positions of the protection switches, when the fault protection switches are disconnected, the voltage difference between the adjacent protection switches is controlled to be smaller, and the safety of the DC-DC converter is further improved.
The multi-path DC-DC converter 2 in the present embodiment forms an inverter with the DC-AC converter 9. The positive output ports of the multi-path DC-DC converter 2 are connected in parallel to the positive input port of the DC-AC converter 9, and the negative output ports of the multi-path DC-DC converter 2 are connected in parallel to the negative input port of the DC-AC converter 9. The multiple DC-DC converters 2 form a DC combiner box 11, the positive output ports of the multiple DC-DC converters 2 are connected in parallel to form a positive output port of the DC combiner box 11, and the negative output ports of the multiple DC-DC converters 2 are connected in parallel to form a negative output port of the DC combiner box 11.
The present embodiment further includes a photovoltaic inverter 10, as shown in fig. 10, the photovoltaic inverter 10 including the DC-DC converter 2 and the DC-AC converter 9 described above. Specifically, the positive output ports of the multiple DC-DC converters 2 are connected in parallel to the positive input port of the DC-AC converter 9, and the negative output ports of the multiple DC-DC converters 2 are connected in parallel to the negative input port of the DC-AC converter 9. The structure of the constituent mechanism and the protection switch of the specific photovoltaic module is as described above, and detailed description thereof is omitted here.
The present embodiment further includes a DC combiner box 11, as shown in fig. 11, where the DC combiner box 11 includes multiple DC-DC converters 2 as described above, and the multiple DC-DC converters 2 are used to access the photovoltaic module 1. The positive output ports of the multiple DC-DC converters 2 are connected in parallel to form a positive output port of the DC combiner box 11, and the negative output ports of the multiple DC-DC converters 2 are connected in parallel to form a negative output port of the DC combiner box 11.
In summary, the DC-DC converter, the photovoltaic inverter and the DC combiner box in the embodiment have at least the following advantages:
1. By reasonably setting the wiring modes of the photovoltaic unit and the tripping direct current switch, the current of each pole of the switch is more balanced, the current utilization rate of the tripping switch is effectively improved under the condition of not changing the type of the switch, the maximum input current capacity of the DC-DC converter can be improved, and the system capacity is conveniently expanded;
2. Through the position of the protection switch which is reasonably arranged at different distances from the handle, when the fault protection switch is disconnected, the voltage difference of the adjacent protection switches is reduced, and the problem of high withstand voltage between the two adjacent protection switches is solved.
As used in this specification and in the claims, the terms "comprises" and "comprising" merely indicate that the steps and elements are explicitly identified, and do not constitute an exclusive list, as other steps or elements may be included in a method or apparatus. The term "and/or" as used herein includes any combination of one or more of the associated listed items.
It should be noted that, unless otherwise specified, when a feature is referred to as being "fixed" or "connected" to another feature, it may be directly or indirectly fixed or connected to the other feature. Further, the descriptions of the upper, lower, left, right, etc. used in the present invention are merely with respect to the mutual positional relationship of the constituent elements of the present invention in the drawings.
The above-described embodiments are provided for illustrating the technical concept and features of the present invention, and are intended to be preferred embodiments for those skilled in the art to understand the present invention and implement the same according to the present invention, not to limit the scope of the present invention. All equivalent changes or modifications made according to the principles of the present invention should be construed to be included within the scope of the present invention.
Claims (10)
1. A DC-DC converter for accessing a photovoltaic module having M photovoltaic units, each of the photovoltaic units comprising one or more photovoltaic modules;
The DC-DC converter comprises a DC-DC circuit, a direct current bus and a plurality of protection switches, wherein the direct current bus is connected with the input end of the DC-DC circuit;
The photovoltaic units are connected to the direct current buses through the protection switches, and each protection switch is used for disconnecting the corresponding photovoltaic unit from the direct current buses when the reverse current of the connected photovoltaic unit is larger than a first current value or exceeds a first current value;
it is characterized in that the method comprises the steps of,
M is a positive integer greater than or equal to 5, and the output voltage of the branch circuit where each photovoltaic unit is located is the same;
The photovoltaic module comprises a first type of photovoltaic unit group and a second type of photovoltaic unit group, the number of the first type of photovoltaic unit group is N, the number of the second type of photovoltaic unit group is K, wherein N is a positive integer and K is a positive integer andEach first type of photovoltaic unit group comprises one photovoltaic unit, and each second type of photovoltaic unit group comprises two photovoltaic units;
Positive output ports of two photovoltaic units in each second type of photovoltaic unit group are connected in series with the same protection switch, and negative output ports of two photovoltaic units in each second type of photovoltaic unit group are connected in series with the same protection switch;
the positive output port of the photovoltaic unit in the first type photovoltaic unit group and the positive output port of the photovoltaic unit in one of the second type photovoltaic unit groups are connected in series with the same protection switch; and the negative output port of the photovoltaic unit in the second type photovoltaic unit group and the negative output port of the photovoltaic unit in the other second type photovoltaic unit group are connected in series with the same protection switch.
2. The DC-DC converter according to claim 1, wherein when N is a positive integer greater than or equal to 2, the protection switches of the series connection of the positive output ports of the photovoltaic units in the different first-type photovoltaic unit groups are different, and the protection switches of the series connection of the negative output ports of the photovoltaic units in the different first-type photovoltaic unit groups are different.
3. A DC-DC converter according to claim 1, wherein the number of the protection switches is P,
4. A DC-DC converter according to claim 1, characterized in that each of the protection switches corresponds to one pole number of a DC-isolating switch comprising a handle and P poles.
5. A DC-DC converter according to claim 4, characterized in that when m=5, p=4, n=1, k=2,
Negative output ports of two photovoltaic units in the first second type photovoltaic unit group are connected to a first protection switch in series, and positive output ports of two photovoltaic units in the first second type photovoltaic unit group are connected to a second protection switch in series;
negative output ports of two photovoltaic units in the second type of photovoltaic unit group are connected to a third protection switch in series, and positive output ports of two photovoltaic units in the second type of photovoltaic unit group are connected to a fourth protection switch in series;
the positive output ports of the photovoltaic units in the first type of photovoltaic unit group are connected in series to the second protection switch, and the negative output ports of the photovoltaic units in the first type of photovoltaic unit group are connected in series to the third protection switch;
The distance between the first protection switch and the handle is smaller than that between the second protection switch and the third protection switch, and the distance between the third protection switch and the handle is smaller than that between the third protection switch and the fourth protection switch.
6. The DC-DC converter according to claim 4, wherein when m=5, p=4, n=1, k=2, positive output ports of two photovoltaic cells in a first of the second type of photovoltaic cell groups are connected in series to a first protection switch, and negative output ports of two photovoltaic cells in the first of the second type of photovoltaic cell groups are connected in series to a second protection switch;
Positive output ports of two photovoltaic units in the second type of photovoltaic unit group are connected to a third protection switch in series, and negative output ports of two photovoltaic units in the second type of photovoltaic unit group are connected to a fourth protection switch in series;
The positive output ports of the photovoltaic units in the first type of photovoltaic unit group are connected to the first protection switch in series, and the negative output ports of the photovoltaic units in the first type of photovoltaic unit group are connected to the fourth protection switch in series;
The distance between the first protection switch and the handle is smaller than that between the second protection switch and the third protection switch, and the distance between the third protection switch and the handle is smaller than that between the third protection switch and the fourth protection switch.
7. The DC-DC converter of claim 1, wherein a plurality of the DC-DC converters and the DC-AC converter form an inverter;
the positive output ports of the DC-DC converters are connected to the positive input ports of the DC-AC converters in parallel, and the negative output ports of the DC-DC converters are connected to the negative input ports of the DC-AC converters in parallel.
8. The DC-DC converter of claim 1, wherein a plurality of the DC-DC converters form a direct current combiner box; the positive output ports of the DC-DC converters are connected in parallel to form a positive output port of the direct current combiner box; and the negative output ports of the DC-DC converters are connected in parallel to form the negative output port of the direct current combiner box.
9. A photovoltaic inverter comprising a DC-AC converter, characterized in that the photovoltaic inverter further comprises a DC-DC converter according to any of claims 1-8; the positive output ports of the DC-DC converters are connected to the positive input ports of the DC-AC converters in parallel, and the negative output ports of the DC-DC converters are connected to the negative input ports of the DC-AC converters in parallel.
10. A direct current combiner box comprising a plurality of DC-DC converters according to any one of claims 1 to 8, the plurality of DC-DC converters being adapted to be connected to a photovoltaic module; the positive output ports of the DC-DC converters are connected in parallel to form a positive output port of the direct current combiner box; and the negative output ports of the DC-DC converters are connected in parallel to form the negative output port of the direct current combiner box.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202410428023.6A CN118412834A (en) | 2024-04-09 | 2024-04-09 | DC-DC converter, photovoltaic inverter and direct current combiner box |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202410428023.6A CN118412834A (en) | 2024-04-09 | 2024-04-09 | DC-DC converter, photovoltaic inverter and direct current combiner box |
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