Input side wiring circuit of inverter, inverter and photovoltaic system

Abstract

The utility model discloses an input side wiring circuit of an inverter, the inverter and a photovoltaic system. The input side wiring circuit of the inverter comprises a plurality of combiner boxes, a plurality of fuses and a DC load switch. Wherein the combiner box comprises a first polarity output end, and the first polarity output end of the combiner box is connected to the direct current load switch through the fuse; the direct current load switch comprises at least two first pole pieces, and the corresponding relation between the first pole pieces and the combiner boxes comprises that the input side of one first pole piece corresponds to the first polarity output ends of at least two combiner boxes; and the output sides of the first pole pieces are electrically connected. According to the utility model, the safety of the combiner box in case of a fault at the back-flow stage is improved, and the use safety of the inverter is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of new energy, and in particular to an input side wiring circuit of an inverter, an inverter and a photovoltaic system. Background Art

[0002] With the development of new energy technologies, their applications are becoming increasingly widespread, and the safety of their use is receiving increasing attention. In existing technologies, centralized inverters are modularized to increase their online availability. For example, the power of a single unit ranges from 500kW to 1MW. Therefore, multiple combiner branches are connected in parallel through DC fuses under the same DC load switch of the centralized inverter. However, when a fault such as a simultaneous positive and negative short circuit to ground, arcing, or reverse polarity occurs in the combiner's downstream stage, the current in other combiner branches flows back through the branch fuses to the short circuit point, or backflow occurs. In such situations, safety issues such as excessively high interrupting voltage, arc extinguishing failure, fault expansion, and even fire can easily occur. Utility Model Content

[0003] The utility model provides an input side wiring circuit of an inverter, an inverter and a photovoltaic system, so as to improve the safety when a failure occurs in the backflow rear stage of a combiner box, and improve the use safety of the inverter.

[0004] According to one aspect of the present invention, an input side wiring circuit of an inverter is provided, comprising: a plurality of combiner boxes, a plurality of fuses and a DC load switch;

[0005] Wherein, the combiner box includes a first polarity output terminal, and the first polarity output terminal of the combiner box is connected to the DC load switch through the fuse;

[0006] The DC load switch includes at least two first pole pieces. The corresponding relationship between the first pole pieces and the combiner boxes includes: the input side of one first pole piece corresponds to the first polarity output ends of at least two combiner boxes; the output sides of the first pole pieces are electrically connected.

[0007] Optionally, the maximum number of the combiner boxes connected to the input side of one first pole piece is determined according to the output current of the combiner box and the maximum withstand current of the fuse.

[0008] Optionally, the maximum number m of the combiner boxes connected to the input side of one first pole piece, the output current I1 of the combiner box, and the maximum withstand current In of the fuse satisfy the following relationship:

[0009] (m-1)*I1≤In.

[0010] Optionally, the number of the first pole pieces is determined according to the maximum number of the combiner boxes and the number of the combiner boxes correspondingly connected to the input side of one of the first pole pieces.

[0011] Optionally, if the number of combiner boxes connected to the input side of each first pole piece is equal, the number p of the first pole pieces, the number n of the combiner boxes, and the number m of the combiner boxes connected to the input side of one first pole piece satisfy the following relationship:

[0012] p*m=n;

[0013] If the number of combiner boxes connected to the input side of each first pole piece is unequal, the number p of the first pole pieces, the number n of the combiner boxes, and the number m1, m2, ..., mp of the combiner boxes connected to the input side of each first pole piece satisfy the following relationship:

[0014] m1+m2+……+mp=n.

[0015] Optionally, the corresponding relationship between the first pole piece and the combiner box further includes: an input side of one first pole piece corresponds to a first polarity output end of the combiner box.

[0016] Optionally, the combiner box further includes a second polarity output terminal, and the second polarity output terminal of the combiner box is connected to the DC load switch through the fuse;

[0017] The DC load switch further includes a second pole piece, and the second pole piece corresponds to the second polarity output end of each of the combiner boxes.

[0018] Optionally, the first polarity output terminal is a positive output terminal, and the second polarity output terminal is a negative output terminal;

[0019] Alternatively, the first polarity output terminal is a negative output terminal, and the second polarity output terminal is a positive output terminal.

[0020] Optionally, the input side wiring circuit of the inverter further includes:

[0021] A plurality of current sensors are connected in series between the fuse and the DC load switch.

[0022] According to another aspect of the present invention, an inverter is provided, comprising: an input-side wiring circuit of the inverter according to any embodiment of the present invention.

[0023] According to another aspect of the present invention, a photovoltaic system is provided, comprising: an input-side wiring circuit of the inverter according to any embodiment of the present invention.

[0024] The embodiment of the present invention increases the number of first pole pieces in the DC load switch, connects the first polarity output terminals of at least two junction boxes in parallel on the input side of the first pole piece, and connects the first pole pieces in parallel on the output side of the DC load switch. The structure is simple, the cost is low, and it is easy to implement. When the inverter is operating normally, its topology is the same as that of the comparative example, but in the event of a fault, the number of junction boxes connected in parallel on the same first pole piece is reduced, thereby reducing the magnitude of the fault current on the abnormal branch, which helps to avoid the fuse of the abnormal branch from blowing, and can protect the integrity of the internal components of the inverter to the greatest extent. Furthermore, since the fuse is not blown, it helps to avoid the safety problems of excessively high breaking voltage, arc extinguishing failure, fault expansion, and even fire in the prior art, thereby improving the safety of the junction box when a fault occurs in the backflow rear stage, and improving the safety of the inverter.

[0025] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 A schematic diagram of an input side wiring circuit of an inverter according to a comparative example provided in an embodiment of the present utility model;

[0028] Figure 2 A schematic diagram of a comparative example provided by an embodiment of the present utility model when multiple positive and negative points are short-circuited to ground simultaneously;

[0029] Figure 3 A schematic diagram of a comparative example provided in an embodiment of the present utility model when reverse connection occurs;

[0030] Figure 4 A schematic diagram of an input-side wiring circuit of an inverter provided by an embodiment of the present utility model;

[0031] Figure 5 A schematic diagram of an input-side wiring circuit of an inverter provided by an embodiment of the present invention when multiple positive and negative points are simultaneously short-circuited to ground;

[0032] Figure 6 A schematic diagram of an input side wiring circuit of an inverter provided by an embodiment of the present utility model when reverse connection occurs;

[0033] Figure 7 A schematic diagram of an input-side wiring circuit of another inverter provided by an embodiment of the present utility model;

[0034] Figure 8 A schematic diagram of an input-side wiring circuit of another inverter provided in an embodiment of the present utility model. DETAILED DESCRIPTION

[0035] In order to help those skilled in the art better understand the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0037] As described in the background, when a combiner box's downstream terminals experience multiple positive and negative short circuits to ground, arcing, or reverse connection, they can easily lead to safety issues such as arc extinguishing failure, fault expansion, and even fire. Research has found the following reasons for this problem.

[0038] Figure 1 This is a schematic diagram of the input side wiring circuit of an inverter provided as a comparative example in an embodiment of the present utility model. Figure 1 Taking four combiner boxes as an example, the input-side wiring circuit of the inverter includes: combiner box 1, combiner box 2, combiner box 3, and combiner box 4. The positive output terminals of each combiner box are connected together through a DC fuse 110 and then connected to the positive pole piece 121 of the DC load switch 120; the negative output terminals of each combiner box are connected together through a DC fuse 110 and then connected to the negative pole piece 122 of the DC load switch 120, so as to realize parallel connection of multiple combiner box branches under the same DC load switch 120.

[0039] For example, the maximum current of each combiner box is 360 A, and the specification of each DC fuse 110 is 400 A. When the inverter operates normally, the maximum current flowing through each DC fuse 110 is 360 A, which will not cause the DC fuse 110 to melt.

[0040] Figure 2 This is a schematic diagram of a comparative example provided by the present utility model when multiple positive and negative points are short-circuited to ground at the same time. Figure 2 There is a situation where multiple positive and negative points in the combiner box's merging stage are short-circuited to the ground at the same time. For example, the negative connection of combiner box 1 and the positive connection of combiner box 2 are short-circuited to the ground at the same time. The DC load switch 120 is immediately disconnected, and the currents of the other combiner box branches flow back toward the short-circuit point 100 through the branch fuses 110. Specifically, the positive current 360A_Imax of combiner box 1, the positive current 360A_Imax of combiner box 3, and the positive current 360A_Imax of combiner box 4 flow back toward the short-circuit point 100 through the fuse 110 of the positive pole + of combiner box 2, so that the fuse 110 of the positive pole + of combiner box 2 is subjected to a current of 1080A_Imax; similarly, the negative current 360A_Imax of combiner box 2, the negative current 360A_Imax of combiner box 3, and the negative current 360A_Imax of combiner box 4 flow back toward the short-circuit point 100 through the fuse 110 of the negative pole - of combiner box 1, so that the fuse 110 of the negative pole - of combiner box 1 is subjected to a current of 1080A_Imax. At this point, the currents borne by fuses 110 connected to the positive terminal (+) of combiner box 2 and fuses 110 connected to the negative terminal (-) of combiner box 1 are both three times the output current of a single combiner box. If this combiner box is used in a photovoltaic system, where the output current is related to light intensity, the current borne by the abnormal branch is three times the maximum output current of a single combiner box based on light intensity. The current borne by fuses 110 in the abnormal branch is called a small overload current.

[0041] Figure 3 This is a schematic diagram of a comparative example provided by the present invention when reverse connection occurs. Figure 3 , there is a situation where the combiner box is reversely connected at the back stage, for example, the positive and negative connections of combiner box 2 are reversed. Figure 3The power supply in the combiner box 2 is positive at the upper end and negative at the lower end. However, for power generation devices such as photovoltaics, the power supply itself is a current source, and its output voltage can be positive or negative. The reverse connection of the combiner box 2 here means that other functional circuits are also provided in the combiner box 2, and these functional circuits have positive and negative characteristics. When the combiner box 2 is reversely connected, the DC load switch 120 is immediately disconnected, and the branch currents of the other combiner boxes are reversed through the branch fuses 110. Specifically, the positive current 360A_Imax of combiner box 1, the positive current 360A_Imax of combiner box 3, and the positive current 360A_Imax of combiner box 4 are reversed through the fuse 110 of the negative pole of combiner box 2, causing the fuse 110 of the negative pole of combiner box 2 to withstand a current of 1080A_Imax. Similarly, the negative current 360A_Imax of combiner box 1, the negative current 360A_Imax of combiner box 3, and the negative current 360A_Imax of combiner box 4 are reversed through the fuse 110 of the positive pole of combiner box 2, causing the fuse 110 of the positive pole of combiner box 2 to withstand a current of 1080A_Imax. At this point, the currents borne by fuses 110 for the positive and negative terminals of combiner box 2 are both three times the output current of a single combiner box. If this combiner box is used in a photovoltaic system, where the output current is related to light intensity, the current borne by the abnormal branch is three times the maximum output current of a single combiner box based on light intensity. The current borne by fuses 110 in the abnormal branch is called a small overload current.

[0042] exist Figure 2 and Figure 3 In the fault scenario shown, the abnormal branch fuse 110 is subjected to a small overload current. When breaking at this small overload current, fuse 110 risks arcing, which can lead to fault expansion. Analysis reveals that the reason for this is that fuse 110 relies on thermal melting, resulting in a long melting time (e.g., over 10 minutes) caused by a small overload current. In the case of non-instantaneous melting, the different slits within the fuse have inconsistent breaking times, causing the breaking voltage of a single slit to exceed the design value. Furthermore, due to the long breaking time, the fuse body temperature rises, weakening the arc extinguishing performance of the quartz and ceramic shell within the fuse, leading to arc extinguishing failure, fault expansion, and even fire.

[0043] In view of this, an embodiment of the present invention provides an input-side wiring circuit of an inverter. Figure 4 This is a schematic diagram of an input side wiring circuit of an inverter provided by an embodiment of the present utility model. Figure 4 The input side wiring circuit of the inverter includes: multiple combiner boxes 230, multiple fuses 210 and a DC load switch 220.

[0044] The combiner box 230 includes a first polarity output terminal ( Figure 4 In the example, the first polarity output terminal is the positive output terminal), the first polarity output terminal of the combiner box 230 is connected to the DC load switch 220 through the fuse 210; similarly, the combiner box 230 also includes a second polarity output terminal ( Figure 4 In the example, the second polarity output terminal is the negative output terminal), the second polarity output terminal of the combiner box 230 is connected to the DC load switch 220 through the fuse 210.

[0045] The DC load switch 220 includes at least two first pole pieces 221. The correspondence between the first pole pieces 221 and the combiner box 230 is as follows: the input side of one first pole piece 221 corresponds to the first polarity output terminals of at least two combiner boxes 230; the output sides of the first pole pieces 221 are electrically connected. The input side of the first pole piece 221 is the side connected to the combiner box 230, and the output side of the first pole piece 221 is the side connected to the subsequent circuit.

[0046] In one embodiment, the first polarity output terminal is a positive output terminal, and accordingly, the first pole piece 221 is a positive pole piece; the second polarity output terminal is a negative output terminal, and accordingly, the second pole piece 222 is a negative pole piece. Then, the embodiment of the utility model can be expressed as follows: the DC load switch 220 includes at least two positive pole pieces, and the corresponding relationship between the positive pole pieces and the junction box 230 includes: the input side of one positive pole piece corresponds to the positive output terminals of at least two junction boxes 230; the output sides of each positive pole piece are electrically connected. Still with Figure 4 For example, the input side of the first positive electrode plate is connected to the positive output end of the combiner box 1 and the positive output end of the combiner box 2 respectively; the input side of the second positive electrode plate is connected to the positive output end of the combiner box 3 and the positive output end of the combiner box 4 respectively; the output sides of the two positive electrode plates are electrically connected together and serve as the positive output end of the DC load switch 220.

[0047] It can be seen that compared with the comparative example, the embodiment of the utility model increases the number of positive pole pieces in the DC load switch 220, and a smaller number of junction boxes are connected in parallel on the input side of the positive pole pieces, and the positive pole pieces are connected in parallel on the output side of the DC load switch 220. This arrangement can solve the problem of poor safety existing in the prior art, and the specific analysis is as follows.

[0048] Figure 5 This is a schematic diagram of an input side wiring circuit of an inverter provided by an embodiment of the present invention when multiple positive and negative points are short-circuited to ground at the same time. Figure 5In the post-merger stage of a combiner box, multiple positive and negative short circuits to ground can occur simultaneously. For example, if the negative terminal of combiner box 1 and the positive terminal of combiner box 2 are simultaneously shorted to ground, DC load switch 220 will immediately open. In this case, the circuits between the parallel combination of combiner boxes 1 and 2 and the parallel combination of combiner boxes 3 and 4 are disconnected, leaving only the backflow problem between combiner boxes 1 and 2. Specifically, the positive current 360A_Imax of combiner box 1 flows back through the fuse 210 on the positive pole of combiner box 2 toward the short-circuit point 200, causing the fuse 210 on the positive pole of combiner box 2 to withstand only the output current 360A_Imax of combiner box 1. Similarly, the negative current 360A_Imax of combiner box 2 flows back through the fuse 210 on the negative pole of combiner box 1 toward the short-circuit point 200, causing the fuse 210 on the negative pole of combiner box 1 to withstand only the output current 360A_Imax of combiner box 2. At this point, the currents carried by the fuses 210 on the positive pole of combiner box 2 and the fuses 210 on the negative pole of combiner box 1 are both the output current of a single combiner box, but in opposite directions. For a fuse 210 with a specification of 400A, the maximum current it can withstand is 360A, which will not cause it to melt.

[0049] Figure 6 This is a schematic diagram of the input side wiring circuit of an inverter provided by an embodiment of the present invention when reverse connection occurs. Figure 6 There is a situation where the combiner box's post-merger connection is reversed, for example, the positive and negative connections of combiner box 2 are reversed. When combiner box 2 is reversed, the DC load switch 120 immediately opens. At this time, the circuits between the parallel combination of combiner boxes 1 and 2 and the parallel combination of combiner boxes 3 and 4 are disconnected, and only the reverse current problem exists between combiner boxes 1 and 2. Specifically, the positive current 360A_Imax of combiner box 1 is reversed through the fuse 110 of the negative pole of combiner box 2, causing the fuse 110 of the negative pole of combiner box 2 to withstand a current only equal to the output current 360A_Imax of combiner box 1. Similarly, the negative current 360A_Imax of combiner box 1 is reversed through the fuse 110 of the positive pole of combiner box 2, causing the fuse 110 of the positive pole of combiner box 2 to withstand a current only equal to the output current 360A_Imax of combiner box 1. At this time, the currents borne by the fuses 110 at the positive pole + and the fuses 110 at the negative pole - of the combiner box 2 are both the output current of the single combiner box, but in opposite directions. For a fuse 210 with a specification of 400A, the maximum current it can withstand is 360A, which will not cause it to melt.

[0050] In summary, in the embodiment of the present invention, by increasing the number of positive pole pieces in the DC load switch 220, connecting the positive output terminals of at least two combiner boxes in parallel on the input side of the positive pole piece, and connecting the positive pole pieces in parallel on the output side of the DC load switch 220, the structure is simple, cost-effective, and easy to implement. When the inverter is operating normally, its topology is the same as that of the comparative example. However, in the event of a fault, the number of combiner boxes 230 connected in parallel on the same positive pole piece is reduced, thereby reducing the magnitude of the fault current on the abnormal branch, helping to avoid the fuse of the abnormal branch from blowing, and can maximize the protection of the integrity of the inverter's internal components. Furthermore, because the fuse does not blow, it helps to avoid the safety issues of excessively high interrupting voltage, arc extinguishing failure, fault expansion, and even fire that exist in the prior art, thereby improving the safety of the combiner box when a fault occurs in the backflow stage, and improving the safety of the inverter.

[0051] Continue to see Figure 4 On the basis of the above embodiments, optionally, the input side connection circuit of the inverter further includes a plurality of current sensors 240, each current sensor 240 is connected in series between the fuse 210 and the DC load switch 220. Figure 4 As shown, illustratively, each current sensor 240 is connected in series to the line of the positive output end of each combiner box 230. The current sensor 240 can not only detect the current size on each positive output end line, but also detect the current direction on each positive output end line. For the embodiment of the present utility model, if the inverter is in a grid-connected state, when the controller detects a negative current on the positive output end line, it controls the DC load switch 220 to be disconnected immediately, thereby reducing the number of combiner boxes in parallel, and the circuits between combiner boxes connected to different positive poles are cut off. In this case, the controller can remind the staff by means of an alarm until the staff removes the external fault point and resumes operation.

[0052] In other embodiments, a current sensor 240 may be provided and connected in series not only to the line of the positive output end of each combiner box 230 , but also to the line of the negative output end of each combiner box 230 .

[0053] Continue to see Figure 4Based on the above embodiments, the combiner box 230 optionally further includes a second polarity output terminal, which is connected to the DC load switch 220 via the fuse 210. The DC load switch 220 further includes a second pole piece 222, corresponding to the second polarity output terminal of each combiner box 230. The number of second pole pieces 222 can be one. That is, the number of first polarity output terminals of the combiner box 230 connected to one first pole piece 221 is less than the number of second polarity output terminals of the combiner box 230 connected to the second pole piece 222, but the total number of combiner boxes 230 connected to all first pole pieces 221 is equal to the number of second polarity output terminals of the combiner box 230 connected to the second pole piece 222. Because the first pole piece 221 already disconnects the circuits between the parallel-connected combiner boxes 230 when an abnormality occurs in the downstream stage of the combiner box 230, multiple second pole pieces 222 are not required. This arrangement is conducive to simplifying the circuit structure while ensuring the safe operation of the inverter.

[0054] Based on the above embodiments, the maximum number of combiner boxes 230 connected to the input side of a first pole piece 221 can optionally be determined based on the output current of the combiner box 230 and the maximum current rating of the fuse 210. Specifically, when an abnormality occurs in the downstream circuit of the combiner box 230, the current flowing through the fuse 210 is an integer multiple of the output current of the combiner box 230 and should not exceed the rated current of the fuse 210 to prevent the fuse from blowing. This configuration facilitates accurate determination of the number of combiner boxes 230 connected to the input side of a first pole piece 221, thereby ensuring that the fuse 210 in the abnormal branch circuit does not blow due to a small overload current.

[0055] Based on the above embodiments, optionally, the maximum number m of combiner boxes 230 connected to the input side of a first pole piece 221, the output current I1 of the combiner box 230, and the maximum withstand current In of the fuse 210 satisfy the following relationship: (m-1)*I1≤In. Specifically, as can be seen from the above analysis, when an abnormality occurs in the downstream circuit of a combiner box 230, the current flowing through the abnormal combiner box 230 is the sum of the currents of the other combiner boxes connected in parallel with it. Therefore, the current flowing through the abnormal combiner box 230 is the current of all the combiner boxes 230 connected in parallel minus its own current, that is, the current in the abnormal branch is (m-1)*I1. This current should be less than or equal to the maximum withstand current In (or rated current) of the fuse 210. This configuration can further accurately determine the number of combiner boxes 230 connected to the input side of a first pole piece 221, thereby further ensuring that the fuse 210 in the abnormal branch does not blow due to a small overload current.

[0056] In practical applications, the DC load switch 220 with increased number of pole pieces usually needs to be customized with the manufacturer, so the specific number of pole pieces also needs to be determined.

[0057] Based on the above embodiments, the number of first pole pieces 221 can optionally be determined based on the maximum number of combiner boxes 230 and the number of combiner boxes 230 connected to the input side of a first pole piece 221. Specifically, the sum of the number of combiner boxes 230 connected to the input side of each first pole piece 221 should equal the maximum number of combiner boxes 230. Therefore, after determining the number of combiner boxes 230 connected to the input side of a first pole piece 221 and the maximum number of combiner boxes 230, the number of first pole pieces 221 can be determined. This configuration facilitates accurate determination of the number of pole pieces within the load switch 220 and facilitates customization.

[0058] Based on the above embodiments, optionally, if the number of combiner boxes 230 connected to the input side of each first pole piece 221 is equal, then the number p of first pole pieces 221, the number n of combiner boxes 230 and the maximum number m of combiner boxes 230 connected to the input side of a first pole piece 221 satisfy the following relationship: p*m=n.

[0059] If the number of combiner boxes 230 connected to the input side of each first pole piece 221 is not equal, then the number p of first pole pieces 221, the number n of combiner boxes 230 and the number m1, m2, ..., mp of combiner boxes 230 connected to the input side of each first pole piece 221 satisfy the following relationship: m1+m2+...+mp=n.

[0060] The number of combiner boxes 230 connected to the input side of each first pole piece 221 may be equal or unequal as required. In one embodiment, the number of combiner boxes 230 connected to the input side of each first pole piece 221 may be equal, for example Figure 4 In the embodiment shown, one DC load switch 220 corresponds to four combiner boxes 230. The requirement can be met by setting the first first pole piece 221 and the second first pole piece 221 to be connected to two combiner boxes 230. However, in another embodiment, it is not possible to set the number of combiner boxes 230 connected to the input side of each first pole piece 221 to be equal, for example Figure 7 In the embodiment shown, one DC load switch 220 corresponds to five combiner boxes 230, and the first first pole piece 221 and the second first pole piece 221 are each connected to two combiner boxes 230. At this time, there is still one combiner box 230 left, so the third first pole piece 221 is set to connect to one combiner box 230, which can meet the requirements.

[0061] It should be noted that the above embodiments illustrate that the number of first pole pieces 221 provided just meets the number requirement for combiner boxes 230, and this does not limit the present invention. In other embodiments, a surplus of first pole pieces 221 may be provided. That is, if the number of combiner boxes 230 connected to the input sides of the first pole pieces 221 is equal, p*m>n is set; if the number of combiner boxes 230 connected to the input sides of the first pole pieces 221 is unequal, m1+m2+…+mp>n is set, and the surplus first pole pieces 221 are used for backup.

[0062] Continue to see Figure 7 Based on the above embodiments, optionally, the correspondence between the first pole piece 221 and the combiner box 230 further includes: the input side of one first pole piece 221 corresponds to the first polarity output terminal of one combiner box 230. After the number of combiner boxes 230, the number of first pole pieces 221, and the number of combiner boxes 230 connected to the input side of the first pole piece 221 are determined, it is possible that the combiner boxes 230 cannot be evenly distributed among the first pole pieces 221, resulting in one combiner box 230 remaining. In this case, one first pole piece 221 is connected to one combiner box 230. This configuration helps ensure that the number of combiner boxes 230 connected to each first pole piece 221 is within a safe range.

[0063] It should be noted that, based on the above embodiments, the first polarity output terminal is exemplarily shown as a positive output terminal and the second polarity output terminal is a negative output terminal, that is, the positive electrode is added to reduce the number of combiner boxes 230 connected in parallel when an abnormality occurs in the subsequent circuit of the combiner box 230. This is not a limitation of the present invention. Figure 8 As shown, the first polarity output terminal can also be set as a negative output terminal, and the second polarity output terminal can be set as a positive output terminal, that is, a negative pole piece is added to reduce the number of combiner boxes 230 connected in parallel when an abnormality occurs in the subsequent circuit of the combiner box 230. The technical principle and the effects produced are similar to those of the aforementioned embodiments and will not be repeated here.

[0064] The present invention also provides an inverter, which may be a centralized inverter. The inverter includes a power module and an input-side wiring circuit as provided in any embodiment of the present invention. The output side of a DC load switch is connected to the power module. The technical principles and effects of improving safety achieved by the inverter provided in this embodiment of the present invention are similar to those of the aforementioned embodiments and are not further described.

[0065] The present invention also provides a photovoltaic system comprising photovoltaic panels, power modules, and an input-side wiring circuit for an inverter as provided in any embodiment of the present invention. The output power of the photovoltaic panels flows to subsequent circuits via a combiner box. The technical principles and effects of improving safety achieved by the photovoltaic system provided by this embodiment of the present invention are similar to those of the aforementioned embodiments and are not further elaborated.

[0066] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this utility model can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of this utility model can be achieved. This is not limited herein.

[0067] The above specific embodiments do not limit the scope of protection of this utility model. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model shall be included within the scope of protection of this utility model.

Claims

1. An input side wiring circuit of an inverter, characterized in that: include: Multiple combiner boxes, multiple fuses and DC load switches; Wherein, the combiner box includes a first polarity output terminal, and the first polarity output terminal of the combiner box is connected to the DC load switch through the fuse; The DC load switch includes at least two first pole pieces. The corresponding relationship between the first pole pieces and the combiner boxes includes: the input side of one first pole piece corresponds to the first polarity output ends of at least two combiner boxes; the output sides of the first pole pieces are electrically connected.

2. The input side wiring circuit of the inverter according to claim 1, characterized in that: The maximum number of the combiner boxes connected to the input side of one first pole piece is determined according to the output current of the combiner box and the maximum withstand current of the fuse.

3. The input side wiring circuit of the inverter according to claim 1, characterized in that: The maximum number m of the combiner boxes connected to the input side of one first pole piece, the output current I1 of the combiner box, and the maximum withstand current In of the fuse satisfy the following relationship: (m-1)*I1≤In.

4. The input side connection circuit of the inverter according to claim 2 or 3, characterized in that: The number of the first pole pieces is determined according to the maximum number of the combiner boxes and the number of the combiner boxes connected to the input side of one first pole piece.

5. The input side connection circuit of the inverter according to claim 2 or 3, characterized in that: If the number of combiner boxes connected to the input side of each first pole piece is equal, the number p of the first pole pieces, the number n of the combiner boxes, and the number m of the combiner boxes connected to the input side of one first pole piece satisfy the following relationship: p*m=n; If the number of combiner boxes connected to the input side of each first pole piece is unequal, the number p of the first pole pieces, the number n of the combiner boxes, and the number m1, m2, ..., mp of the combiner boxes connected to the input side of each first pole piece satisfy the following relationship: m1+m2+……+mp=n.

6. The input side wiring circuit of the inverter according to any one of claims 1 to 3, characterized in that: The corresponding relationship between the first pole pieces and the combiner boxes further includes: an input side of one of the first pole pieces corresponds to a first polarity output end of the combiner box.

7. The input side connection circuit of the inverter according to claim 1, characterized in that: The combiner box further comprises a second polarity output terminal, and the second polarity output terminal of the combiner box is connected to the DC load switch through the fuse; The DC load switch further includes a second pole piece, and the second pole piece corresponds to the second polarity output end of each of the combiner boxes.

8. The input side connection circuit of the inverter according to claim 7, characterized in that: The first polarity output terminal is a positive output terminal, and the second polarity output terminal is a negative output terminal; Alternatively, the first polarity output terminal is a negative output terminal, and the second polarity output terminal is a positive output terminal.

9. The input side connection circuit of the inverter according to claim 1, characterized in that: Also includes: A plurality of current sensors are connected in series between the fuse and the DC load switch.

10. An inverter, characterized in that: include: The input side wiring circuit of the inverter according to any one of claims 1 to 9.

11. A photovoltaic system, characterized in that: include: The input side wiring circuit of the inverter according to any one of claims 1 to 9.

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