Planar mutual inductor, arc discharge detection circuit and photovoltaic system
By flexibly switching the number of primary winding layers and secondary windings of the planar current transformer, the problems of current transformer core saturation and detection accuracy in photovoltaic systems are solved, high-precision arc detection is achieved, and photovoltaic module failures are avoided.
Patent Information
- Application Number
- CN202423152352.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2034-12-19
AI Technical Summary
In existing photovoltaic systems, current transformers are prone to core saturation and overheating, which reduces the accuracy of arc detection. Furthermore, increasing the secondary turns ratio when the input current is small affects the detection accuracy, making it impossible to accurately detect the generation of arcs.
A planar current transformer is used to avoid core saturation and output saturation by flexibly switching the number of primary winding layers and secondary windings, thus ensuring the accuracy of arc detection. The transformer includes a core assembly, a primary winding circuit board, and a secondary winding circuit board. Accuracy control is achieved using a secondary switching circuit and an external signal processing circuit.
Without increasing the size of the magnetic components, core saturation and output saturation are avoided, ensuring the accuracy of arc detection and preventing photovoltaic module failure.
Smart Images
Figure CN223598495U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field of power electronics, especially to a planar mutual inductor, an arc detection circuit and a photovoltaic system. BACKGROUND
[0002] In the fire accidents caused by various electrical safety problems of the photovoltaic system, the disaster caused by the direct current arc accounts for a high proportion. Therefore, in order to be able to investigate and maintain the safety of the photovoltaic module in time, it is required to detect the arc on the input side of the photovoltaic inverter of the photovoltaic module.
[0003] In the prior art, the mutual inductor is usually used for current sampling, and after filtering, the energy change in different frequency bands is obtained through frequency spectrum analysis, so as to detect whether the arc is generated in the circuit. However, the direct current input current range of the photovoltaic system is large, which is easy to cause the saturation of the magnetic core of the mutual inductor and the serious heating phenomenon; at the same time, the ground impedance of the power inductor and the input filter capacitor of the later-stage boost circuit will cause the current fluctuation on the mutual inductor to be large, which affects the precision of the arc detection circuit, and even causes the saturation of the output circuit.
[0004] Therefore, in order to avoid the saturation of the magnetic core, the mutual inductor usually needs to use a larger magnetic core, which increases the volume of the magnetic component; at the same time, in order to avoid the saturation of the arc detection circuit output, it is required to increase the secondary side turn ratio of the mutual inductor, but increasing the secondary side turn ratio of the mutual inductor in the case of small input current will affect the precision of the arc detection, and cannot accurately detect whether the arc is generated in the circuit, and thus cannot avoid the photovoltaic module failure caused by the arc. SUMMARY
[0005] The utility model embodiment proposes a planar mutual inductor, which can avoid the saturation of the magnetic core without increasing the volume of the magnetic component, and can flexibly switch the secondary side turn ratio, which can avoid the saturation of the arc detection circuit output while ensuring the measurement precision requirement of the arc detection, and avoid the photovoltaic module failure caused by the arc; the planar mutual inductor comprises:
[0006] A magnetic core assembly, at least one primary winding circuit board and a plurality of secondary winding circuit boards; wherein each primary winding circuit board comprises a plurality of primary winding layers stacked together, and each primary winding layer is provided with a primary winding coil; each secondary winding circuit board is provided with a secondary winding coil;
[0007] The magnetic core assembly penetrates the at least one primary winding circuit board and the plurality of secondary winding circuit boards;
[0008] Among them, part or all of the at least one primary winding circuit board are connected in sequence to constitute the effective primary winding of the planar mutual inductor, and part or all of the plurality of secondary winding circuit boards are connected in sequence to constitute the effective secondary winding of the planar mutual inductor.
[0009] In a possible embodiment, part or all of the plurality of secondary winding circuit boards are connected in series to form the effective secondary winding.
[0010] In a possible embodiment, each secondary winding circuit board is provided with a secondary winding switching tap.
[0011] The planar transformer further comprises a secondary winding switching circuit, the secondary winding switching circuit comprising a plurality of switching transistors, each switching transistor being connected with a secondary winding switching tap.
[0012] In a possible embodiment, the secondary winding switching circuit further comprises a comparison module.
[0013] One side of the comparison module is connected with each switching transistor, and the other side is connected with an external signal processing circuit.
[0014] In a possible embodiment, the plurality of primary winding layers comprises a plurality of primary forward winding layers and a plurality of primary reverse winding layers.
[0015] Part or all of the plurality of primary forward winding layers are connected in series, and part or all of the plurality of primary reverse winding layers are connected in series to form the effective primary winding.
[0016] The number of primary forward winding layers in the effective primary winding is the same as the number of primary reverse winding layers.
[0017] In a possible embodiment, each primary forward winding layer is provided with a primary forward switching tap, and each primary reverse winding layer is provided with a primary reverse switching tap.
[0018] The planar transformer further comprises a plurality of primary forward winding relays and a plurality of primary reverse winding relays.
[0019] One side of each primary forward winding relay is connected with a primary forward switching tap, and the other side of each primary forward winding relay is connected with a positive electrode of a to-be-detected circuit. One side of each primary reverse winding relay is connected with a primary reverse switching tap, and the other side of each primary reverse winding relay is connected with a negative electrode of the to-be-detected circuit.
[0020] The utility model embodiment further provides a kind of arc detection circuit, the arc detection circuit includes: external signal processing circuit and the plane mutual inductor above, the input side of the plane mutual inductor is arranged in the loop to be detected, the current variation of the loop to be detected is inducted, the output side of plane mutual inductor is connected with the external signal processing circuit, to realize when arc detection, without increasing the volume of plane mutual inductor magnetic component, can avoid magnetic core saturation, and can flexibly switch secondary side turns ratio, while avoiding the output saturation of arc detection circuit, guarantee the measurement accuracy requirement of arc detection, avoid the photovoltaic module failure caused by arc.
[0021] In one possible embodiment, the external signal processing circuit includes a sampling resistor and a high-pass filter circuit, the sampling resistor collects the output voltage of the output side of the plane mutual inductor, and determines whether arc occurs through the high-pass filter circuit.
[0022] The utility model embodiment further provides a kind of photovoltaic system, which includes the arc detection circuit above.
[0023] The utility model embodiment provides a plane mutual inductor, which includes a magnetic core assembly, at least one primary winding circuit board and a plurality of secondary winding circuit boards. Each primary winding circuit board includes a plurality of primary winding layers stacked together, and each primary winding layer is provided with a primary winding coil. Each secondary winding circuit board is provided with a secondary winding coil. The magnetic core assembly penetrates through the at least one primary winding circuit board and the plurality of secondary winding circuit boards. Part or all of the at least one primary winding circuit board are sequentially connected to form an effective primary winding of the plane mutual inductor, and part or all of the plurality of secondary winding circuit boards are sequentially connected to form an effective secondary winding of the plane mutual inductor. The number of layers of the primary winding circuit board of the plane mutual inductor can be changed, and the number of secondary winding circuit boards can also be changed. Therefore, the saturation of the magnetic core can be eliminated by changing the number of layers of the primary winding layer, and the sampling accuracy under different application conditions can be adapted by changing the number of secondary winding circuit boards. In this way, the saturation of the magnetic core can be avoided without increasing the volume of the magnetic component, and the secondary winding turns ratio can be flexibly switched to ensure the measurement accuracy requirement of arc detection and avoid photovoltaic module failure caused by arc. BRIEF DESCRIPTION OF DRAWINGS
[0024] To more clearly illustrate the technical solutions in the embodiments of the utility model or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the utility model, and other drawings can be obtained by those skilled in the art without creative effort. In the drawings:
[0025] Figure 1The structure diagram of the arc-drawing detection circuit is provided in the embodiment of the utility model.
[0026] Figure 2 The structure diagram of the mutual inductor is provided in the embodiment of the utility model. DETAILED DESCRIPTION
[0027] In order to make the purpose, technical scheme and advantages of the embodiment of the utility model clearer and more apparent, the embodiment of the utility model is further described in detail below with reference to the drawings. Herein, the illustrative embodiment of the utility model and its description are used to explain the utility model, but not as a limitation on the utility model.
[0028] In the description of the present specification, "comprising", "including", "having", "containing" and the like are all open terms, that is, they mean containing but not limited to. The description of the terms "one embodiment", "one specific embodiment", "some embodiments", "for example" and the like means that the specific features, structures or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. The order of the steps involved in the embodiments is used to illustrate the implementation of the present application, and the order of the steps is not limited, and can be appropriately adjusted as needed.
[0029] In the arc-drawing detection circuit in the existing photovoltaic system, the current range of the direct current input side of the photovoltaic inverter fluctuates greatly, which is easy to cause the saturation of the magnetic core of the mutual inductor and the serious heating phenomenon; at the same time, the impedance to ground of the power inductor and the input filter capacitor of the later-stage boost circuit can cause the current fluctuation of the mutual inductor to be large, which affects the precision of the arc-drawing detection circuit, and even causes the saturation of the output circuit. In order to avoid the saturation of the magnetic core, a larger magnetic core is usually needed to be used, which increases the volume of the magnetic component; in order to avoid the saturation of the output of the arc-drawing detection circuit, the secondary winding ratio of the mutual inductor needs to be increased, but the increase of the secondary winding ratio of the mutual inductor under the condition of small input current will affect the precision of the arc-drawing detection, and the arc-drawing detection cannot be accurately performed, and thus the photovoltaic module failure caused by the arc-drawing cannot be avoided.
[0030] Based on this, the embodiment of the utility model provides a mutual inductor, and an arc-drawing detection circuit and a photovoltaic system based on the mutual inductor. When the arc-drawing detection is performed, the mutual inductor does not need to increase the volume of the magnetic component, can avoid the saturation of the magnetic core, and can flexibly switch the secondary winding ratio, which can avoid the saturation of the output of the arc-drawing detection circuit while ensuring the measurement precision requirement of the arc-drawing detection, and avoid the photovoltaic module failure caused by the arc-drawing.
[0031] Figure 1The utility model discloses a structure diagram of arc detection circuit provided in the embodiment of the utility model, Figure 2 The utility model discloses a structure diagram of planar mutual inductor provided in the embodiment of the utility model.
[0032] The utility model discloses a planar mutual inductor, arc detection circuit and photovoltaic system. Figure 1 And Figure 2 The utility model discloses a planar mutual inductor, arc detection circuit and photovoltaic system.
[0033] The utility model discloses a photovoltaic system, the photovoltaic system includes the arc detection circuit as Figure 1 The arc detection circuit is connected in series in the photovoltaic system, and the front stage of the arc detection circuit is a photovoltaic input (PV source), and the rear stage is a boost inversion circuit, the PV source provides input energy for the boost inversion circuit, and the arc detection circuit is used for detecting whether arc occurs in the whole loop.
[0034] As Figure 1 The arc detection circuit includes a planar mutual inductor 1 and an external signal processing circuit 2, and the input side of the planar mutual inductor 1 is arranged in the loop to be detected to induct the current change of the loop to be detected, and the output side of the planar mutual inductor 1 is connected with the external signal processing circuit.
[0035] In specific implementation, the loop to be detected can be a loop formed by the PV source and the boost inversion circuit, the input side of the planar mutual inductor 1 is arranged in the loop to be detected, in the embodiment, the input side of the planar mutual inductor 1 is connected with the positive pole PV+ and the negative pole PV- of the PV source at the same time, and the output side of the planar mutual inductor 1 is connected with the external signal processing circuit 2, in an embodiment, the input side of the planar mutual inductor 1 can be the primary winding side of the planar mutual inductor, and the output side of the planar mutual inductor 1 can be the secondary winding side of the planar mutual inductor.
[0036] In an embodiment, the above-mentioned external signal processing circuit 2 includes a sampling resistor 21 and a high-pass filter operation circuit 22, the sampling resistor 21 collects the output voltage of the output side of the planar mutual inductor 1, and judges whether arc occurs through the high-pass filter operation circuit 22.
[0037] In specific implementation, the sampling resistor 21 can collect the output voltage of the output side of the planar mutual inductor 1, and judge whether the output voltage exceeds the set voltage threshold range through the secondary side switching circuit 16 of the planar mutual inductor 1, and then determine whether the output is saturated and whether the input current is small, in the case that the output is not saturated and the input current is small, whether arc occurs is judged through the high-pass filter operation circuit 22. The above-mentioned secondary side switching circuit 16 is described in detail in the following embodiment, and no redundant description is made here.
[0038] The above-mentioned planar mutual inductor 1 is described in detail below.
[0039] AsFigure 2 As shown in the above, the planar transformer 1 comprises a magnetic core assembly 11, at least one primary winding circuit board 12 and a plurality of secondary winding circuit boards 13; wherein each primary winding circuit board 12 comprises a plurality of primary winding layers stacked together, each primary winding layer is provided with a primary winding coil; each secondary winding circuit board 13 is provided with a secondary winding coil;
[0040] The magnetic core assembly 11 penetrates through the at least one primary winding circuit board 12 and the plurality of secondary winding circuit boards 13;
[0041] Wherein, part or all of the at least one primary winding circuit board 12 is connected in sequence to form an effective primary winding of the planar transformer, and part or all of the plurality of secondary winding circuit boards 13 is connected in sequence to form an effective secondary winding of the planar transformer.
[0042] In specific implementation, without increasing the volume of the magnetic component, in the case of saturation of the magnetic core, the number of primary winding layers of the access circuit can be changed to eliminate the saturation of the magnetic core, so that the primary winding layers of the access circuit can form the effective primary winding; and in the case of output saturation, the number of secondary winding circuit boards of the access circuit can be increased, and in the case of small input current, the number of secondary winding circuit boards of the access circuit can be reduced, so that the secondary winding circuit boards of the access circuit can form the effective secondary winding.
[0043] In an embodiment, the magnetic core assembly 11 can be composed of two mutually abutting magnetic cores, one magnetic core 111 is a mountain-shaped core, and one magnetic core 112 is a one-shaped core, both of which form a closed magnetic circuit, and the at least one primary winding circuit board 12 and the plurality of secondary winding circuit boards 13 are placed in the middle of the mountain-shaped core 111.
[0044] In an embodiment, the plurality of primary winding layers comprises a plurality of primary positive winding layers 121 and a plurality of primary negative winding layers 122. Part or all of the plurality of primary positive winding layers 121 are connected in series, and part or all of the plurality of primary negative winding layers 122 are connected in series to form an effective primary winding. Wherein, the number of primary positive winding layers 121 and the number of primary negative winding layers 122 in the effective primary winding are the same, and the current direction of the primary positive winding layer 121 and the current direction of the primary negative winding layer 122 are opposite. For example, Figure 2 As shown in the above, the planar transformer 1 comprises a magnetic core assembly 11, at least one primary winding circuit board 12 and a plurality of secondary winding circuit boards 13; wherein each primary winding circuit board 12 comprises a plurality of primary winding layers stacked together, each primary winding layer is provided with a primary winding coil; each secondary winding circuit board 13 is provided with a secondary winding coil;
[0045] In implementation, based on the above description, the input side of the planar transformer 1 is connected to the positive pole PV+ and the negative pole PV- of the PV source, and thus, as shown in the figure, one end of the primary positive winding layer 121 can be connected to PV+, and the other end can be connected to the positive pole of the boost inversion circuit; one end of the primary negative winding layer 122 can be connected to PV-, and the other end can be connected to the negative pole of the boost inversion circuit. In this way, the primary winding current directions of PV+ and PV- are opposite, and the interference of common-mode current can be offset. Figure 1
[0046] In one embodiment, part or all of the plurality of secondary winding circuit boards 13 are connected in series to form an effective secondary winding. As shown in the figure, Figure 1 each secondary winding circuit board can be an independent secondary winding.
[0047] It should be noted that the primary winding of the planar transformer usually carries a large current and has a small number of turns, and thus the number of layers of the primary winding circuit board can be set according to the number of photovoltaic inputs; the number of secondary winding circuit boards can be set according to the sampling requirement.
[0048] In the embodiment of the utility model, the number of layers of the primary winding of the access circuit is changed to avoid core saturation, and in implementation, in order to change the number of layers of the primary winding of the access circuit, each primary positive winding layer 121 is provided with a primary positive switching tap; each primary negative winding layer 122 is provided with a primary negative switching tap.
[0049] The planar transformer 1 can further include a plurality of primary positive winding relays 14 and a plurality of primary negative winding relays 15.
[0050] Each primary positive winding relay 14 is connected to a primary positive switching tap on one side, and connected to the positive pole of the to-be-detected circuit on the other side; each primary negative winding relay 15 is connected to a primary negative switching tap on one side, and connected to the negative pole of the to-be-detected circuit on the other side.
[0051] In implementation, considering that the primary current is large, a relay is used as a switching switch. The number of primary positive winding relays 14 can be the same as the number of layers of the primary positive winding layer, and the number of primary negative winding relays 15 can be the same as the number of layers of the primary negative winding layer, Figure 1 two primary positive winding layers 121 and two primary negative winding layers 122 are shown, corresponding to 2 primary positive winding relays 14 and 2 primary negative winding relays 15.
[0052] Specifically, one side of each primary-side positive winding relay 14 is connected to the primary-side positive switching tap of a primary-side positive winding layer 121 to control the primary-side positive winding layer to access the circuit, and the other side of the primary-side positive winding relay 14 is connected to the positive terminal of the circuit to be tested (i.e., the positive terminal of the boost inverter circuit after the circuit to be tested); each primary-side negative winding relay 15 is connected to the primary-side negative switching tap of a primary-side negative winding layer 122 to control the primary-side negative winding layer to access the circuit, and the other side of the primary-side negative winding relay 15 is connected to the negative terminal of the circuit to be tested (i.e., the negative terminal of the boost inverter circuit after the circuit to be tested).
[0053] In this embodiment of the utility model, output saturation is avoided and sampling accuracy is ensured by changing the number of secondary winding circuit boards in the access circuit. In specific implementation, in order to change the number of secondary winding circuit boards in the access circuit, each secondary winding circuit board 13 is provided with a secondary winding switching tap.
[0054] The planar transformer also includes a secondary-side switching circuit 16, which includes a plurality of switching transistors 162, each of which is connected to a primary winding switching tap.
[0055] In practice, the number of switching transistors 162 in the secondary switching circuit 16 can be the same as the number of secondary winding circuit boards 13. Figure 1 Three secondary winding circuit boards 13 are shown, and correspondingly, there are also three switching transistors 162. Each switching transistor 162 is connected to a secondary winding switching tap of a secondary winding circuit board 13, and the secondary winding circuit board 13 can be connected to the circuit by the switching transistor.
[0056] In one embodiment, the secondary-side switching circuit 16 may further include a comparison module 161;
[0057] The comparison module 161 is connected to each switching transistor 162 on one side and to the sampling resistor 21 of the external signal processing circuit 2 on the other side.
[0058] In specific implementation, the comparison module 161 may include a comparator and a drive circuit. The comparator is used to compare the secondary voltage signal (i.e. the output voltage on the output side of the planar transformer) collected by the sampling resistor 21. When the switching of the switching transistor is triggered, the closing of the switching transistor 162 is controlled by the enable of the drive circuit, thereby controlling each secondary winding circuit board 13 to enter or exit the circuit.
[0059] In specific implementation, such as Figure 1 As shown, in the secondary-side switching circuit 16, each switching transistor is connected in series with a resistor and a capacitor. The resistor is used to limit the current in the circuit, and the capacitor is used to filter and protect against interference and noise in the circuit.
[0060] Based on the above plane mutual inductor, arc detection circuit and photovoltaic system, when the photovoltaic system works, the input current of the direct current side of the photovoltaic system is sampled into the arc detection circuit through the plane mutual inductor, and if the input current is too high, the temperature of the magnetic core of the plane mutual inductor is high. Therefore, first, whether the temperature of the magnetic core of the plane mutual inductor is abnormal can be detected through the temperature sensor, and if it is detected that the temperature of the magnetic core is too high, it is considered that the magnetic core is saturated, at this time, the primary side positive / negative winding relay of the plane mutual inductor can be controlled to switch the primary winding layer, so that the number of turns of the primary winding is +1, the magnetic induction intensity is reduced, and the saturation of the magnetic core is eliminated. Then, the secondary voltage signal (the output voltage of the output side of the plane mutual inductor) collected by the sampling resistor enters the secondary switching circuit, and the comparator of the secondary switching circuit judges whether the secondary voltage signal exceeds the set voltage threshold range. If the secondary voltage signal exceeds the upper limit of the voltage threshold, it is considered that the sampling circuit output is saturated, and the sampling accuracy is limited, at this time, the switching switch tube of the secondary switching circuit can be controlled through the driving circuit to add the next reserved secondary winding circuit board into the circuit. Similarly, if the secondary voltage signal exceeds the lower limit of the threshold, the switching switch tube of the secondary switching circuit can be controlled through the driving circuit to switch and reduce a group of secondary winding circuit boards connected to the circuit, thereby ensuring the detection accuracy of a wide range of currents. If the secondary voltage signal is within the set threshold range, it is judged whether arc occurs through the high-pass filtering operation circuit, and once the arc abnormal state is identified, the control system triggers protection.
[0061] In summary, the plane mutual inductor provided by the embodiment of the utility model includes: a magnetic core assembly, at least one primary winding circuit board and a plurality of secondary winding circuit boards; wherein each primary winding circuit board includes a plurality of primary winding layers stacked together, and each primary winding layer is provided with a primary winding coil; each secondary winding circuit board is provided with a secondary winding coil; the magnetic core assembly penetrates through the at least one primary winding circuit board and the plurality of secondary winding circuit boards; wherein part or all of the at least one primary winding circuit board are sequentially connected to form an effective primary winding of the plane mutual inductor, and part or all of the plurality of secondary winding circuit boards are sequentially connected to form an effective secondary winding of the plane mutual inductor. The plane mutual inductor of the embodiment of the utility model, the number of layers of the primary winding circuit board connected to the circuit can be changed, and the number of the secondary winding circuit boards can also be changed, therefore, the saturation of the magnetic core can be eliminated by changing the number of layers of the primary winding layer, and the sampling accuracy under different application conditions can be adapted by changing the number of the secondary winding circuit boards, in this way, without increasing the volume of the magnetic component, the saturation of the magnetic core can be avoided, and the secondary turn ratio can be flexibly switched, the measurement accuracy requirement of arc detection is ensured, and photovoltaic module failure caused by arc is avoided.
[0062] The above-described specific embodiments further specifically describe the purposes, technical solutions and beneficial effects of the present application, and it should be understood that the above-described specific embodiments are merely examples of the present application and are not intended to limit the protection scope of the present application, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. A planar transformer, characterized by The planar transformer comprises a magnetic core assembly, at least one primary winding circuit board and a plurality of secondary winding circuit boards; wherein each primary winding circuit board comprises a plurality of primary winding layers stacked together, each primary winding layer being provided with a primary winding coil; and each secondary winding circuit board is provided with a secondary winding coil; The magnetic core assembly penetrates through the at least one primary winding circuit board and the plurality of secondary winding circuit boards; Part or all of the at least one primary winding circuit board are sequentially connected to form an effective primary winding of the planar transformer, and part or all of the plurality of secondary winding circuit boards are sequentially connected to form an effective secondary winding of the planar transformer.
2. The planar transformer of claim 1, wherein, Part or all of the plurality of secondary winding circuit boards are connected in series to form the effective secondary winding.
3. The planar transformer of claim 2, wherein, Each secondary winding circuit board is provided with a secondary winding switching tap; The planar transformer further comprises a secondary winding switching circuit, which comprises a plurality of switching transistors, each switching transistor being connected with a secondary winding switching tap.
4. The planar transformer of claim 3, wherein, The secondary winding switching circuit further comprises a comparison module; One side of the comparison module is connected with each switching transistor, and the other side is connected with an external signal processing circuit.
5. The planar transformer of claim 1, wherein, The plurality of primary winding layers comprises a plurality of primary forward winding layers and a plurality of primary negative winding layers; Part or all of the plurality of primary forward winding layers are connected in series, and part or all of the plurality of primary negative winding layers are connected in series to form the effective primary winding; The number of primary forward winding layers and the number of primary negative winding layers in the effective primary winding are the same.
6. The planar transformer of claim 5, wherein, Each primary forward winding layer is provided with a primary forward switching tap, and each primary negative winding layer is provided with a primary negative switching tap; The planar transformer further comprises a plurality of primary forward winding relays and a plurality of primary negative winding relays; One side of each primary forward winding relay is connected with a primary forward switching tap, and the other side is connected with a positive pole of a to-be-detected circuit; and one side of each primary negative winding relay is connected with a primary negative switching tap, and the other side is connected with a negative pole of the to-be-detected circuit.
7. An arc detection circuit, characterized by The arc detection circuit comprises an external signal processing circuit and the planar transformer according to any one of claims 1-6, wherein the input side of the planar transformer is provided in a to-be-detected circuit to induce current change of the to-be-detected circuit, and the output side of the planar transformer is connected with the external signal processing circuit.
8. The arc draw detection circuit of claim 7, wherein, The external signal processing circuit comprises a sampling resistor and a high-pass filter operation circuit, wherein the sampling resistor collects output voltage of the output side of the planar transformer, and the high-pass filter operation circuit is used to determine whether arc occurs.
9. A photovoltaic system characterized by, The photovoltaic system comprises the arc detection circuit according to any one of claims 7-8.