Power conversion device and power generation system
By using PCB Rogowski coils for arc fault detection in photovoltaic inverters, the problem of high cost caused by the large size of current transformers in photovoltaic inverters is solved, realizing the miniaturization and cost reduction of power conversion devices, and improving the accuracy of arc detection.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- HUAWEI TECH CO LTD
- Filing Date
- 2026-01-21
- Publication Date
- 2026-07-30
AI Technical Summary
In photovoltaic inverters, the large size of the current transformer leads to high cost, and it is difficult to effectively detect arcing problems on the DC side.
Arc fault detection is performed using a PCB Rogowski coil. By vertically mounting the arc detection board on the power board and laying the Rogowski coil around the through-hole on the arc detection board, the amount of iron core used is reduced. Combined with the return wire, the influence of interfering magnetic fields is offset, thereby improving the detection accuracy.
It effectively reduces the size and cost of power conversion devices, while improving the accuracy and reliability of arc detection.
Smart Images
Figure CN2026073972_30072026_PF_FP_ABST
Abstract
Description
Power conversion devices and power generation systems
[0001] This application claims priority to Chinese Patent Application No. 202510121389.3, filed on January 24, 2025, with the China National Intellectual Property Administration, entitled "Power Conversion Device and Power Generation System", the entire contents of which are incorporated herein by reference. Technical Field
[0002] This application relates to the field of power supply technology, and in particular to a power conversion device and a power generation system. Background Technology
[0003] To prevent DC arcing caused by poor contact at the PV terminals in the DC-side circuit of a photovoltaic (PV) system, PV inverters are required to have arcing detection capabilities. Specifically, the PV inverter accurately acquires the characteristic signal of an electric arc through a current transformer located on the DC side. Then, the PV inverter processes the arcing characteristic signal through filtering and amplification, and analyzes the processed signal to determine whether arcing exists on the DC side. Although PV inverters can achieve arcing detection using current transformers, the large size of current transformers (composed of a closed iron core and windings) leads to excessively high costs for PV inverters. Summary of the Invention
[0004] This application provides a power conversion device and a power generation system that can reduce the size of the power conversion device, thereby effectively reducing the cost of the power conversion device.
[0005] In a first aspect, this application provides a power conversion device, comprising a power board and an arc detection board, the arc detection board being vertically disposed on the surface of the power board. The arc detection board includes a first through-hole extending through the arc detection board along its thickness direction, and a Rogowski coil is laid around the first through-hole on the arc detection board. A power conversion circuit is disposed on the power board, and the connecting wire between the power conversion circuit and the DC input of the power conversion device includes a U-shaped wire extending through the first through-hole along the thickness direction of the arc detection board, with both sides of the U-shaped wire located on opposite sides of the arc detection board. The Rogowski coil is used to sense the alternating current on the connecting wire, generating an arc induction signal for arc fault detection in the power conversion device.
[0006] In this embodiment, the Rogowski coil laid on the arc detection board can be understood as a PCB Rogowski coil. The power conversion device detects arc faults through the PCB Rogowski coil. Since the PCB Rogowski coil is printed on a printed circuit board (PCB) and is an air-core coil, it obviously does not contain an iron core. Therefore, the size of the power conversion device can be reduced, thereby effectively reducing the cost of the power conversion device. In addition, the arc detection board is vertically arranged on the surface of the power board, making the arc detection board occupy a small area on the power board, which is conducive to the miniaturization design of the power conversion device, further effectively reducing the cost of the power conversion device.
[0007] In conjunction with the first aspect, in a first possible embodiment, the arc detection board includes a first layer and a second layer stacked together, and a plurality of vias surrounding a first through-hole and penetrating the first and second layers along the thickness direction of the arc detection board. Each of the plurality of vias includes a conductive first via, a second via, a third via, and a fourth via. The first and second vias are located on the same side of the line containing the third and fourth vias, and the first and fourth vias are also located on the same side of the line containing the second and third vias. The Rogowski coil includes a conductive coating applied to the inner wall of each via in each group of vias, a first connecting wire between the first and second vias in each group of vias, a second connecting wire between the third and fourth vias, a third connecting wire between the second and fourth vias, and a fourth connecting wire between the first via of one group of vias and the third via of the other group of vias in any two adjacent groups of vias. The first and second connecting wires are printed on the first layer, and the third and fourth connecting wires are printed on the second layer.
[0008] In this embodiment, the Rogowski coil consists of a conductive coating applied to the inner wall of each via in a plurality of vias on the arc detection plate and connecting wires printed on the arc detection plate. It does not increase the volume of the arc detection plate, thus facilitating the miniaturization of the power conversion device. Furthermore, when the interior angles of the quadrilateral formed by the lines connecting the first, second, third, and fourth vias to adjacent vias do not include right angles (i.e., when the first, second, third, and fourth vias are misaligned with each other), the number of turns in the Rogowski coil can be increased, thereby increasing the mutual inductance coefficient. This results in a greater induced electromotive force gain in the Rogowski coil within a preset frequency band (e.g., 10kHz to 60kHz), enabling accurate arc detection and reliable arc detection.
[0009] In conjunction with the first possible implementation of the first aspect, in the second possible implementation, if the number of layers of the arc detection plate is odd, the arc detection plate further includes a third layer located between the first and second layers. Multiple sets of vias also penetrate the third layer along the thickness direction of the arc detection plate. The power conversion device also includes a return conductor for the Rogowski coil, which is printed on the third layer. After connecting one end of the Rogowski coil, the return conductor passes through the channel formed by the Rogowski coil and the arc detection plate, thereby generating an induced electromotive force on the return conductor in the opposite direction to the induced electromotive force generated by the ripple current in the Rogowski coil's induction connection conductor.
[0010] In this embodiment, since the arc fault detection provided by this application simultaneously detects multiple connecting wires between the power conversion device and the DC input of the power conversion circuit, and all of these connecting wires pass through the Rogowski coil and are all current-carrying conductors being measured, when one of these connecting wires arcs, the ripple current in the other connecting wires acts as an interference current, affecting the arc detection accuracy. Therefore, a return wire can be added to the Rogowski coil. The vertical component of the interference magnetic field generates an induced electromotive force in the return wire that is equal in magnitude and opposite in direction to the additional electromotive force. This cancels out the influence of the vertical component on the Rogowski coil, thereby improving the detection accuracy of the Rogowski coil.
[0011] In conjunction with the first possible implementation of the first aspect, in the three possible implementations, if the number of layers of the arc detection plate is even, the arc detection plate further includes a third and fourth layer plate stacked together, located between the first and second layers plate. Multiple sets of vias also penetrate the third and fourth layers plate along the thickness direction of the arc detection plate. The power conversion device further includes two return wires of the Rogowski coil, which are printed on the third and fourth layers plate respectively. Either of the two return wires is connected to one end of the Rogowski coil and then passes through the channel formed by the Rogowski coil and the arc detection plate, thereby generating an induced electromotive force on the two return wires in the opposite direction to the induced electromotive force generated by the ripple current in the Rogowski coil's connecting wires.
[0012] In this embodiment, since the arc fault detection provided by this application simultaneously detects multiple connecting wires between the power conversion device and the DC input of the power conversion circuit, and all of these connecting wires pass through the Rogowski coil and are all current-carrying conductors being measured, when one of these connecting wires arcs, the ripple current in the other connecting wires acts as an interference current, affecting the arc detection accuracy. Therefore, a return wire can be added to the Rogowski coil. The vertical component of the interference magnetic field generates an induced electromotive force in the return wire that is equal in magnitude and opposite in direction to the additional electromotive force. This cancels out the influence of the vertical component on the Rogowski coil, thereby improving the detection accuracy of the Rogowski coil.
[0013] In combination with any of the first to third possible implementations of the first aspect, in four possible implementations, the gap formed by the Rogowski coil around the first through hole is smaller than the diameter of the first through hole.
[0014] In this embodiment, this arrangement allows the Rogowski coil to form a nearly closed structure around the first through-hole. For a nearly closed Rogowski coil, the position of the conductor being measured has almost no effect on the mutual inductance value; that is, the output voltage is not affected by the distance of the conductor being measured from the center of the Rogowski coil. When the conductor being measured deviates from the center of the Rogowski coil, the magnetic flux of each turn of the coil changes compared to the ideal case where no deviation occurs. However, the magnetic flux increases on the side closer to the measured current and decreases on the side farther from the measured current, and the total magnetic flux remains almost unchanged. Therefore, this application does not require special settings for the distance between the connecting wire and the center of the Rogowski coil to ensure the accuracy of the induced electromotive force generated by the Rogowski coil, thereby achieving reliable arc detection.
[0015] In conjunction with any of the first to fourth possible implementations of the first aspect, in the fifth possible implementation, the U-shaped conductor is a copper busbar.
[0016] In this embodiment, the U-shaped conductor is a copper busbar, which has good heat dissipation and corrosion resistance. Therefore, it is not only suitable for high-current applications, but also improves the accuracy of arc detection results.
[0017] In conjunction with any of the first to fifth possible embodiments of the first aspect, in the sixth possible embodiment, the power conversion device further includes a signal conditioning circuit and a controller. The signal conditioning circuit is connected to a Rogowski coil and is used to filter and amplify the arc-induced signal to generate an arc detection signal. The controller is used to shut down the power conversion device when the sum of the gains corresponding to the signals obtained by the fast Fourier transform of the arc detection signal within a preset frequency band exceeds a threshold.
[0018] In conjunction with the sixth possible implementation of the first aspect, in the seventh possible implementation, the power conversion device further includes a self-test winding, wherein the controller is further configured to output an alternating current to the self-test winding before the power conversion circuit starts operating. A Rogowski coil is further configured to sense the alternating current flowing through the self-test winding and generate a self-test induction signal. A signal conditioning circuit is further configured to filter and amplify the self-test induction signal to generate a self-test detection signal. The controller is further configured to, if the sum of the gains corresponding to the signals after the fast Fourier transform of the self-test detection signal within a preset frequency band is greater than a threshold, indicate the presence of an electric arc on the self-test winding, that is, that the arc fault detection function of the power conversion device is normal, and then control the power conversion circuit to start operating.
[0019] In this embodiment, during each power-on process, the power conversion device will determine whether the arc fault detection function of the power conversion device is normal through the self-test winding. Only after confirming that the arc fault detection function of the power conversion device is normal will the power conversion circuit be controlled to start working, and then the arc detection signal will be obtained through the Rogowski coil to perform arc fault detection. Therefore, the arc detection results can be more reliable and accurate.
[0020] In conjunction with the seventh possible implementation of the first aspect, in the eighth possible implementation, the arc detection plate further includes a second through hole that penetrates the arc detection plate along its thickness direction. The second through hole is located between the first through hole and the Rogowski coil, and the distance between the second through hole and the first through hole is greater than the safety distance. The self-test winding is laid on the arc detection plate and passes through the second through hole.
[0021] For example, the self-test winding is printed on the arc detection board in the form of copper foil. This arrangement does not increase the volume of the arc detection board, thus facilitating the miniaturization design of the power conversion device.
[0022] In conjunction with any of the sixth to eighth possible implementations of the first aspect, in the ninth possible implementation, the signal conditioning circuit is disposed on the surface of the arc detection board and is located around the Rogowski coil.
[0023] In this embodiment, the signal conditioning circuit is disposed on the surface of the arc detection plate and located around the Rogowski coil to prevent the signal conditioning circuit from interfering with the normal operation of the Rogowski coil, thereby effectively ensuring the detection performance of the Rogowski coil. Furthermore, the Rogowski coil is located between the signal conditioning circuit and the connecting wires, enabling the Rogowski coil to form effective electromagnetic shielding and preventing the alternating magnetic field generated near the connecting wires from interfering with the signal conditioning circuit.
[0024] In conjunction with any of the first aspect to the ninth possible implementation of the first aspect, in the tenth possible implementation, the arc detection plate includes a plurality of first through holes, a Rogowski coil surrounds the plurality of first through holes, the plurality of first through holes correspond one-to-one with a plurality of connecting wires between the power conversion circuit and the DC input of the power conversion device, a U-shaped wire in one of the connecting wires passes through a first through hole along the thickness direction of the arc detection plate, and the two sides of the U-shaped wire in one of the connecting wires are respectively located on both sides of the arc detection plate.
[0025] In this embodiment, the way in which multiple connecting wires between the power conversion circuit and the DC input of the power conversion device pass through the through hole can include not only the way in which multiple connecting wires all pass through a first through hole (such as a rectangular through hole with a small width), but also the way in which multiple connecting wires pass through multiple first through holes respectively. This makes the structure of the arc detection board diverse, thereby making the structure of the power conversion device diverse and highly flexible.
[0026] Secondly, this application provides a power generation system including a power conversion device and a photovoltaic module or energy storage battery. The DC input of the power conversion device is connected to the photovoltaic module or energy storage battery. The power conversion device includes a power board and an arc detection board, with the arc detection board vertically disposed on the surface of the power board. The arc detection board includes a first through-hole extending through the arc detection board along its thickness direction, and a Rogowski coil is laid around the first through-hole on the arc detection board. A power conversion circuit is disposed on the power board, and the connecting wire between the power conversion circuit and the DC input of the power conversion device includes a U-shaped wire extending through the first through-hole along the thickness direction of the arc detection board, with both sides of the U-shaped wire located on opposite sides of the arc detection board. The Rogowski coil is used to sense alternating current on the connecting wire, generating an arc induction signal for arc fault detection of the power conversion device.
[0027] In this embodiment, the Rogowski coil laid on the arc detection board can be understood as a PCB Rogowski coil. The power conversion device detects arc faults through the PCB Rogowski coil. Since the PCB Rogowski coil is printed on the PCB and is an air-core coil, it obviously does not contain an iron core. Therefore, the size of the power conversion device can be reduced, thereby effectively reducing the cost of the power conversion device and, consequently, the cost of the power generation system. Furthermore, the arc detection board is vertically mounted on the surface of the power board, resulting in a smaller footprint. This facilitates the miniaturization of the power conversion device, further reducing its cost and, consequently, the cost of the power generation system. Attached Figure Description
[0028] Figure 1 is a schematic diagram of an application scenario of the power generation system provided in this application;
[0029] Figure 2a is a schematic diagram of the circuit structure of the inverter provided in this application;
[0030] Figure 2b is a schematic diagram of the internal structure of the inverter provided in this application;
[0031] Figure 2c is another internal structure diagram of the inverter provided in this application;
[0032] Figure 2d is another internal structure diagram of the inverter provided in this application;
[0033] Figure 3 is a schematic diagram of another application scenario of the power generation system provided in this application;
[0034] Figure 4 is a schematic diagram of the power generation system provided in this application;
[0035] Figure 5a is a structural schematic diagram of the power conversion device provided in this application;
[0036] Figure 5b is another structural schematic diagram of the power conversion device provided in this application;
[0037] Figure 5c is another structural schematic diagram of the power conversion device provided in this application;
[0038] Figure 6 is a wiring diagram of the Rogowski coil provided in this application;
[0039] Figure 7 is a schematic diagram of the position of the self-test winding provided in this application. Detailed Implementation
[0040] The power conversion device and power generation system provided in this application are applicable to various fields such as photovoltaic power generation, energy storage power generation, new energy smart microgrids, and power transmission and distribution. The power conversion device provided in this application can be an inverter, a power conversion system (PCS), an uninterruptible power supply (UPS), etc., suitable for different application scenarios, such as photovoltaic power supply scenarios, energy storage power supply scenarios, photovoltaic-energy storage hybrid power supply scenarios, and UPS power supply scenarios. The following explanation uses photovoltaic power supply scenarios and energy storage power supply scenarios as examples.
[0041] Referring to Figure 1, which is a schematic diagram of an application scenario of the power generation system provided in this application. In a photovoltaic power supply scenario, the power generation system provided in this application is the photovoltaic power generation system shown in Figure 1, and the power conversion device provided in this application is any one of the inverters 11 to 1n shown in Figure 1. The photovoltaic power generation system includes inverter 11, ..., inverter 1n, photovoltaic module PV111, photovoltaic module PV112, ..., photovoltaic module PV1n1 and photovoltaic module PV1n2. The DC input i111 of inverter 11 is connected to the positive terminal of photovoltaic module PV111, the DC input i112 is connected to the negative terminals of photovoltaic modules PV111 and PV112, and the DC input i113 is connected to the positive terminal of photovoltaic module PV112; ...; the DC input i1n1 of inverter 1n is connected to the positive terminal of photovoltaic module PV1n1, the DC input i1n2 is connected to the negative terminals of photovoltaic modules PV1n1 and PV1n2, and the DC input i1n3 is connected to the positive terminal of photovoltaic module PV1n2. The AC outputs o11 of inverter 11, ..., and the AC output o1n of inverter 1n are connected in parallel to the AC power grid or household appliances.
[0042] The structures of each inverter in inverters 11 to 1n are identical; the following description uses inverter 11 as an example. As shown in Figure 2a, inverter 11 includes an arc detection module, a DC / DC conversion circuit, a DC / AC conversion circuit, and a controller. The DC input i111 of inverter 11 is connected to the DC input i111a of the DC / DC conversion circuit, the DC input i112 of inverter 11 is connected to the DC input i111b of the DC / DC conversion circuit, and the DC input i113 of inverter 11 is connected to the DC input i111c of the DC / DC conversion circuit. The DC output of the DC / DC conversion circuit is connected to the DC input of the DC / AC conversion circuit, and the AC output of the DC / AC conversion circuit is connected to the AC output of inverter 11. An arc detection module is installed between the DC inputs of inverter 11 (including i111, i112, and i113) and the DC inputs of the DC / DC converter circuit (including i111a, i111b, and i111c). It is used to sense the AC current on the connecting wire a between the DC input i111 of inverter 11 and the DC input i111a of DC / DC converter circuit, the connecting wire b between the DC input i112 of inverter 11 and the DC input i111b of DC / DC converter circuit, and the connecting wire c between the DC input i113 of inverter 11 and the DC input i111c of DC / DC converter circuit, and generate an arc induction signal.
[0043] To better understand the relative positions of the arc detection module, connecting wires a to c, and the DC / DC conversion circuit in inverter 11, the following description uses the arc detection module as a Rogowski coil and refers to the structural schematic diagrams of inverter 11 shown in Figures 2b to 2d to introduce inverter 11. As shown in Figure 2b, inverter 11 includes a power board 111 and an arc detection board 112, with the arc detection board 112 vertically disposed on the surface of the power board 111. The arc detection board 112 includes an arc-shaped first through-hole 1121 that penetrates the arc detection board 112 along its thickness direction. A Rogowski coil 1122 is laid around the first through-hole 1121 on the arc detection board 112. The power board 111 is equipped with a power conversion circuit 1111, namely the DC / DC conversion circuit and DC / AC conversion circuit shown in Figure 2a. A connecting wire a is provided between the DC input of the power conversion circuit 1111 (i.e., the DC input of the DC / DC conversion circuit) and the DC input of the inverter 11. This includes a connecting wire a between the DC input i111a of the power conversion circuit 1111 and the DC input i111 of the inverter 11; a connecting wire b between the DC input i111b of the power conversion circuit 1111 and the DC input i112 of the inverter 11; and a connecting wire c between the DC input i111c of the power conversion circuit 1111 and the DC input i113 of the inverter 11. These correspond to the three wires passing through the first through hole 1121 in Figure 2c. Taking connecting wire a as an example, connecting wire a includes a U-shaped wire that passes through the first through hole along the thickness direction of the arc detection plate. The two sides of the U-shaped wire are located on opposite sides of the arc detection plate. For ease of understanding, the U-shaped wire is divided into three parts: the first connecting wire segment a1, the second connecting wire segment a2, and the third connecting wire segment a3, as shown in Figure 2d. Specifically, the first connecting wire segment a1, which is arched, passes through the first through hole 1121 along the thickness direction of the arc detection plate 112. The second connecting wire segment a2 and the third connecting wire segment a3 are respectively connected to the two ends of the first connecting wire segment a1, extend along the thickness direction of the power plate 111, and are arranged on both sides of the arc detection plate 112.
[0044] After the photovoltaic power generation system starts operating, inverters 11 to 1n sequentially convert and invert the DC power output from their respective connected photovoltaic modules to obtain AC power that meets the requirements of the AC power grid, thereby supplying power to the AC power grid or household appliances. During the operation of each inverter, the Rogowski coil on the arc detection board of each inverter senses the AC current on the connecting wire between the inverter and the DC input of the DC / DC conversion circuit, generating an arc induction signal. Subsequently, the controller in each inverter performs arc fault detection based on the arc induction signal generated by the Rogowski coil.
[0045] It's understandable that the Rogowski coil laid on the arc detection board can be considered a PCB Rogowski coil. The inverter uses the PCB Rogowski coil for arc fault detection. Since the PCB Rogowski coil is printed on the PCB and is an air-core coil, it obviously does not contain an iron core. Therefore, the size of the inverter can be reduced, thereby effectively reducing the cost of the inverter.
[0046] Referring to Figure 3, which is a schematic diagram of another application scenario of the power generation system provided in this application. In the energy storage power supply scenario, the power generation system provided in this application is the energy storage power generation system shown in Figure 3, and the power conversion device provided in this application is any one of the DC / DC converters 11 to 1n shown in Figure 3, or any one of the energy storage converters shown in Figure 3. The following description takes the DC / DC converter as an example: The energy storage power generation system includes DC / DC converter 11 and its connected energy storage converter, ..., DC / DC converter 1n and its connected energy storage converter, battery clusters Bat111, Bat112, ..., Bat1n1 and Bat1n2. DC input i111 of DC / DC converter 11 is connected to the positive terminal of battery cluster Bat111, DC input i112 is connected to the negative terminals of battery cluster Bat111 and Bat112, and DC input i113 is connected to the positive terminal of battery cluster Bat112; ...; DC input i1n1 of DC / DC converter 1n is connected to the positive terminal of battery cluster Bat1n1, DC input i1n2 is connected to the negative terminals of battery cluster Bat1n1 and Bat1n2, and DC input i1n3 is connected to the positive terminal of battery cluster Bat1n2. The AC outputs of the above n energy storage converters are connected in parallel to the AC power grid or household appliances.
[0047] Here, the only difference between the internal structure of any of the above n DC / DC converters and the internal structure of the inverter 11 in Figure 1 is that the power conversion circuit in any DC / DC converter is a DC / DC conversion circuit. For the structural description of other parts in any DC / DC converter besides the power conversion circuit, please refer to the description of the corresponding part of the inverter 11 in the embodiment shown in Figure 1, which will not be repeated here.
[0048] After the energy storage power generation system starts operating, DC / DC converters 11 to 1n convert the DC power output from their respective connected battery clusters into DC power and output it to their respective connected energy storage converters. These n energy storage converters then invert the received DC power to obtain AC power that meets the requirements of the AC power grid, thereby supplying power to the AC power grid or household appliances. During the operation of each DC / DC converter, the Rogowski coil on the arc detection board of each DC / DC converter senses the AC current in the connecting wire between the DC / DC converter and the DC / DC conversion circuit, generating an arc induction signal. Subsequently, each DC / DC converter performs arc fault detection based on the arc induction signal generated by the Rogowski coil.
[0049] It is understandable that the Rogowski coil laid on the arc detection board can be understood as a PCB Rogowski coil. The DC / DC converter uses the PCB Rogowski coil for arc fault detection. Since the PCB Rogowski coil is printed on the PCB and is an air-core coil, it obviously does not contain an iron core. Therefore, the size of the DC / DC converter can be reduced, thereby effectively reducing the cost of the DC / DC converter.
[0050] The above are merely examples of application scenarios for the power generation system provided in this application, and are not exhaustive. This application does not limit the application scenarios.
[0051] The working principle of the power conversion device and power generation system provided in this application will be illustrated below with reference to Figures 4 to 7.
[0052] Referring to Figure 4, which is a structural schematic diagram of the power generation system provided in this application, the power generation system includes power conversion devices 11, ..., 1n, DC power supplies 21, ..., and 2n, where n is a positive integer. The DC input i11 of power conversion device 11 is connected to DC power supply 21, ..., and the DC input i1n of power conversion device 1n is connected to DC power supply 2n. The outputs o11, ..., of power conversion device 11 and the output o1n of power conversion device 1n are connected in parallel to the power grid. The aforementioned n DC power supplies can be photovoltaic modules or energy storage batteries.
[0053] Since each power conversion device in the power generation system has the same structure, for ease of explanation, the following description uses power conversion device 11 as an example. As shown in Figure 5a, power conversion device 11 includes a housing 110, a power board 111, an arc detection board 112, a DC input i11, and an output o11. Both the power board 111 and the arc detection board 112 are located inside the housing 110, with the arc detection board 112 vertically positioned on the surface of the power board 111. The arc detection board 112 includes a first through hole 1121, which penetrates the arc detection board 112 along its thickness direction. Since Figure 5a shows a schematic diagram of the power board 111 and the arc detection board 112 at one angle, to more clearly describe the positional relationship between them, the following description will also include schematic diagrams of the power board 111 and the arc detection board 112 at two other angles, as shown in Figures 5b and 5c. As shown in Figures 5b and 5c, a Rogowski coil 1122 is laid around the first through-hole 1121 on the arc detection plate 112. A power conversion circuit 1111 (including a DC / DC conversion circuit and / or a DC / AC conversion circuit) is provided on the power board 111. Connecting wires a, b, and c are sequentially arranged between the DC input of the power conversion circuit 1111 and the DC input of the power conversion device 11. In practical applications, there are multiple connecting wires between the DC input of the power conversion circuit 1111 and the DC input of the power conversion device 11, and the distance between any two adjacent connecting wires is greater than the safety distance.
[0054] The following describes the connection wire between the DC input of the power conversion circuit 1111 and the DC input of the power conversion device 11, taking connecting wire a as an example. Connecting wire a includes a U-shaped wire and a wire located on the power board 111. For ease of understanding, the U-shaped wire is considered as a combination of three parts, namely the combination of the first connecting wire segment a1, the second connecting wire segment a2, and the third connecting wire segment a3 shown in Figures 5a and 5b. The wire located on the power board 111 in connecting wire a is considered as two parts, namely the fourth connecting wire segment a4 and the fifth connecting wire segment a5 shown in Figures 5a and 5b. The first connecting wire segment a1 passes through the first through hole 1121 along the thickness direction of the arc detection plate 112. The second connecting wire segment a2 and the third connecting wire segment a3 are respectively connected to the two ends of the first connecting wire segment a1, and after extending along the thickness direction of the power board 111, they are respectively connected to one end of the fourth connecting wire segment a4 and one end of the fifth connecting wire segment a5, and are arranged on both sides of the arc detection plate 112. The other end of the fourth connecting wire segment a4 and the other end of the fifth connecting wire segment a5 are respectively connected to the DC input i11 of the power conversion device 11 and the DC input of the power conversion circuit 1111, and both the fourth connecting wire segment a4 and the fifth connecting wire segment a5 are laid on the power board 111.
[0055] For example, the first connecting wire segment a1, the second connecting wire segment a2, and the third connecting wire segment a3 are all copper busbars, which have good heat dissipation and corrosion resistance. Therefore, they are not only suitable for high-current applications, but also improve the accuracy of arc detection results. The fourth connecting wire segment a4 and the fifth connecting wire segment a5 are copper foils printed on the power board 111, which does not increase the volume of the power board 111, thus facilitating the miniaturization design of the power conversion device 11. In addition, when the first connecting wire segment a1 to the third connecting wire segment a3 are copper busbars and the fourth connecting wire segment a4 and the fifth connecting wire segment a5 are copper foils, the power board 111 also includes two conductive holes. The two conductive holes are respectively connected to one end of the fourth connecting wire segment a4 and one end of the fifth connecting wire segment a5. The second connecting wire segment a2 and the third connecting wire segment a3, which are made of copper busbars, are respectively inserted into the two conductive holes, and a reliable conductive connection between the second connecting wire segment a2 and the fourth connecting wire segment a4, and a reliable conductive connection between the third connecting wire segment a3 and the fifth connecting wire segment a5 are achieved by welding. Optionally, the fourth connecting conductor segment a4 and the fifth connecting conductor segment a5 can also be made of copper busbars. In practical applications, the materials of the first to fifth connecting conductor segments can be reasonably set according to actual needs, and this application does not limit this.
[0056] The output of the power conversion circuit 1111 is connected to the output o11 of the power conversion device 11. A portion of the connecting wire d between the output of the power conversion circuit 1111 and the output o11 of the power conversion device 11 is laid on the power board 111. Both the DC input i11 and the output o11 of the power conversion device 11 are housed within the casing 110 to facilitate connection between the power conversion device 11 and other external power supply or electrical equipment. The DC power output from the DC power supply 21 can be supplied from the DC input i11 to the power conversion device 11, and then output from the output o11.
[0057] It should be noted that the first through-hole 1121 shown in Figures 5a to 5c is an example of one in number and an arc shape. That is, regardless of whether there is one or more connecting wires between the power conversion circuit 1111 and the DC input of the power conversion device 11, all connecting wires between the power conversion circuit 1111 and the DC input of the power conversion device 11 pass through the same first through-hole. Optionally, if there are multiple connecting wires between the power conversion circuit 1111 and the DC input of the power conversion device 11, the number of first through-holes can also be multiple. Specifically, the arc detection plate 112 includes multiple first through-holes, and the distance between any two adjacent first through-holes is greater than the safety distance; the Rogowski coil 1122 surrounds the multiple first through-holes, and the multiple first through-holes correspond one-to-one with the multiple connecting wires between the power conversion circuit 1111 and the DC input of the power conversion device 11. Taking the connecting wires between the power conversion circuit 1111 and the DC input of the power conversion device 11 shown in Figure 5b as connecting wire a, connecting wire b, and connecting wire c, the arc detection plate 112 includes three first through holes, namely first through hole 1121a, first through hole 1121b, and first through hole 1121c. Connecting wire a passes through its corresponding first through hole 1121a, connecting wire b passes through its corresponding first through hole 1121b, and connecting wire c passes through its corresponding first through hole 1121c. For the specific implementation of how each of the connecting wires a, b, and c passes through its corresponding first through hole, please refer to the description of the positions of the first to fifth connecting wire segments of connecting wire a in the embodiments shown in Figures 5a and 5b; it will not be repeated here.
[0058] In addition, the power conversion device 11 also includes a controller 1112 and a signal conditioning circuit 1123 connecting the two ends of the Rogowski coil 1122. For example, as shown in FIG5c, the controller 1112 is disposed on the surface of the power board 111; the signal conditioning circuit 1123 is disposed on the surface of the arc detection board 112 and located around the Rogowski coil 1122 to prevent the signal conditioning circuit 1123 from interfering with the normal operation of the Rogowski coil 1122, thereby effectively ensuring the detection effect of the Rogowski coil 1122. Furthermore, the Rogowski coil 1122 is located between the signal conditioning circuit 1123 and the connecting wire, enabling the Rogowski coil 1122 to form an effective electromagnetic shield, preventing the alternating magnetic field generated near the connecting wire from interfering with the signal conditioning circuit 1123. In practical applications, the signal conditioning circuit 1123 can be any circuit with filtering and amplification functions. The input terminal of the signal conditioning circuit 1123 is connected to both ends of the Rogowski coil 1122 to receive the arc-induced signal generated by the Rogowski coil 1122; the output terminal of the signal conditioning circuit 1123 is connected to the controller 1112 to output an arc detection signal to the controller 1112. Optionally, the signal conditioning circuit 1123 and the controller 1112 can both be located on the same circuit board, such as the power board 111 or the arc detection board 112. It is understood that, in specific settings, the relative positions between the signal conditioning circuit 1123 and the Rogowski coil 1122 can be reasonably set according to actual needs to ensure the stable operation of the signal conditioning circuit 1123 and the Rogowski coil 1122, which will not be elaborated here.
[0059] The pattern formed by the Rogowski coil 1122 surrounding the first through-hole 1121 can be a closed pattern (such as a ring, including a circular ring or a rectangular ring) or an approximately closed pattern. Here, an approximately closed pattern refers to a gap (L in Figure 5c) formed by the Rogowski coil 1122 surrounding the first through-hole 1121 that is greater than 0 and smaller than the diameter of the first through-hole 1121. Here, taking a circular ring formed by the Rogowski coil 1122 surrounding the first through-hole 1121 as an example, the wiring method of the Rogowski coil 1122 will be introduced with reference to Figure 6. Assume that the arc detection plate 112 is composed of n stacked plates, including a first plate and a second plate. As shown in Figure 6, the arc detection plate 112 also includes multiple sets of vias surrounding the first through-hole 1121 and penetrating the first and second plates along the thickness direction of the arc detection plate 112. The first group of vias in the multiple via sets includes conductive vias e11, e21, e31, and e41. The second group of vias in the multiple via sets includes conductive vias e12, e22, e32, and e42. Since the relative positions and relationships between the vias in each group are the same, the first group of vias will be used as an example for ease of explanation below. As shown in Figure 6, the first via e11 and the second via e21 are located on the same side of the line containing the third via e31 and the fourth via e41. Furthermore, the first via e12 and the fourth via e42 are located on the same side of the line containing the second via e21 and the third via e31. In other words, the positional relationship between the first via e11, the second via e21, the third via e31 and the fourth via e41 can be simply regarded as the first via e11, the second via e21, the third via e31 and the fourth via e41 being located at the four vertices of a quadrilateral. The Rogowski coil 1122 includes a conductive coating applied to the inner wall of each via in each group of vias, a first connecting wire between the first and second vias in each group of vias, a second connecting wire between the third and fourth vias, a third connecting wire between the second and fourth vias, and a fourth connecting wire between the first via of one group of vias and the third via of the other group of vias in any two adjacent groups of vias. The first and second connecting wires are printed on the first layer, and the third and fourth connecting wires are printed on the second layer.Taking the first group of vias as an example, the first connecting wire is f11 in Figure 6, the second connecting wire is f12 in Figure 6, and the third connecting wire is f13 in Figure 6. The fourth connecting wire between the first via e11 in the first group of vias and the third via e32 in the second group of vias is f14 in Figure 6. Here, the fourth connecting wire f14 in Figure 6 is not routed according to the shortest path between the first via e11 and the third via e32. This is because the diameter of the second via e21 is larger. Therefore, in order to avoid the fourth connecting wire passing through the second via e21 and causing the Rogowski coil to fail, the zigzag segment method shown in Figure 6 is used to route it around the second via e21. It should be noted that the first to fourth vias in each group of vias in Figure 6 are arranged in a clockwise direction. In practical applications, the first to fourth vias in each group of vias can also be arranged in a counterclockwise direction.
[0060] The Rogowski coil 1122 is used to sense the alternating current on the connecting wire between the DC input i11 of the power conversion device 11 and the DC input of the power conversion circuit 1111, for the purpose of detecting arc faults in the power conversion device 11.
[0061] Specifically, the Rogowski coil 1122 in this application is a PCB Rogowski coil. According to the law of electromagnetic induction, the alternating current in the connecting wire generates a mutual inductance electromotive force in the coil: V = M*(di / dt), where M is the mutual inductance coefficient of the PCB Rogowski coil. That is, when the connecting wire is located at the center of the PCB Rogowski coil, the alternating current on the connecting wire will generate a proportional alternating voltage on the PCB Rogowski coil, i.e., an arc-induced signal. Subsequently, the signal conditioning circuit 1123 filters and amplifies the arc-induced signal to generate an arc detection signal. If the sum of the gains of the arc detection signal after fast Fourier transform within a preset frequency band is greater than the threshold Kth, the controller 1112 indicates that an arc exists on the connecting wire and controls the power conversion device 11 to shut down. Since the noise frequency band when an arc occurs on the DC side of the inverter is mainly concentrated between 10kHz and 60kHz, the preset frequency band can be taken as 10kHz to 60kHz. K1 < Kth < K2, where K1 and K2 are determined by statistical data obtained from multiple experimental tests. K1 is determined by k1 at multiple different times, such as the average or mode of multiple k1 values. k1 represents the sum of gains of the arc detection signals within the preset frequency band after Fast Fourier Transform when there is no arc on the connecting wire. K2 is determined by k2 at multiple different times, such as the average or median of multiple k2 values. k2 represents the sum of gains of the arc detection signals within the preset frequency band after Fast Fourier Transform when there is an arc on the connecting wire. For example, Kth is set to 18.
[0062] Furthermore, according to the law of electromagnetic induction, interference currents perpendicular or parallel to the current-carrying conductor will generate an interference magnetic field in the Rogowski coil, affecting the mutual inductance and inducing an additional electromotive force in the PCB Rogowski coil, thus affecting the accuracy of current measurement. Since the arc fault detection provided in this application simultaneously detects multiple connecting wires between the power conversion device 11 and the DC input of the power conversion circuit, and all of these connecting wires pass through the PCB Rogowski coil and are all current-carrying conductors being measured, when one of these connecting wires arcs, the ripple current in the other connecting wires is equivalent to an interference current, affecting the arc detection accuracy. Therefore, one or two return wires can be added to the PCB Rogowski coil. The vertical component of the interference magnetic field generates an induced electromotive force in the return wire that is equal in magnitude and opposite in direction to the additional electromotive force. This can cancel the influence of the vertical component on the Rogowski coil, thereby improving the detection accuracy of the PCB Rogowski coil.
[0063] Here, the number of return wires in the PCB Rogowski coil depends on whether the number of layers n of the arc detection board 112 is odd or even, as follows:
[0064] When n is an odd number, the n-layer plate also includes a third layer plate, and the power conversion device 11 also includes a return wire of the Rogowski coil 1122. The third layer plate is located between the first and second layers, and multiple vias of the Rogowski coil 1122 penetrate the third layer plate along the thickness direction of the arc detection plate 112. A return wire of the Rogowski coil 1122 is printed on the third layer plate and, after connecting to one end (i.e., the output end) of the Rogowski coil 1122, passes through the channel formed by the Rogowski coil 1122 and the arc detection plate 112. This generates an induced electromotive force on the return wire that is opposite in direction to the induced electromotive force generated by the ripple current (interference current) in the other connecting wires induced by the Rogowski coil 1122, thereby reducing or even canceling the influence of the vertical component of the interference magnetic field generated by the interference current within the Rogowski coil 1122 on the Rogowski coil 1122. For example, a return wire of the Rogowski coil 1122, as shown in Figure 6, is a trace that is approximately circular around the first through-hole 1121 and located within the annular region formed by the Rogowski coil 1122. Preferably, in order to minimize the influence of the interfering magnetic field on the Rogowski coil 1122, the direction of the induced electromotive force generated on the return wire should be opposite to the direction of the induced electromotive force generated by the interfering current, and the magnitude of the induced electromotive force generated on the return wire should be the same as the magnitude of the induced electromotive force generated by the interfering current, so as to counteract the influence of the vertical component of the interfering magnetic field generated by the interfering current within the Rogowski coil 1122 on the Rogowski coil 1122.
[0065] For example, if n is 5, the arc detection plate 112 further includes a top plate and a bottom plate, with a first layer plate, a third layer plate, and a second layer plate stacked sequentially between the top plate and the bottom plate. Both the top plate and the bottom plate are coated with copper as shielding. The first and second layers plate serve as the wiring layers for the Rogowski coil 1122, and the third layer plate serves as the wiring layer for one return wire of the Rogowski coil 1122. Obviously, this arrangement allows one return wire of the Rogowski coil 1122 to be located in the center layer of the arc detection plate 112 with a 5-layer plate structure, thereby minimizing the influence of the vertical component of the interfering magnetic field on the Rogowski coil 1122.
[0066] When n is even, the n-layer plate also includes a third and fourth layer plate stacked together, and the power conversion device 11 also includes two return wires of the Rogowski coil 1122. The third and fourth layer plates are both located between the first and second layer plates, and multiple vias of the Rogowski coil 1122 penetrate the third and fourth layer plates along the thickness direction of the arc detection plate 112. The two return wires of the Rogowski coil 1122 are printed on the third and fourth layer plates respectively. Either of the two return wires is connected to one end of the Rogowski coil 1122 (i.e., the output end) and then passes through the channel formed by the Rogowski coil 1122 and the arc detection plate 112. This generates an induced electromotive force on the two return wires that is opposite in direction to the induced electromotive force generated by the ripple current (interference current) in the other connecting wires induced by the Rogowski coil 1122, thereby reducing or even canceling the influence of the vertical component of the interference magnetic field generated by the interference current within the Rogowski coil 1122 on the Rogowski coil 1122. Preferably, in order to minimize the influence of the interfering magnetic field on the Rogowski coil 1122, the direction of the induced electromotive force generated on the two return wires is opposite to the direction of the induced electromotive force generated by the interfering current, and the magnitude of the induced electromotive force generated on the two return wires is the same as the magnitude of the induced electromotive force generated by the interfering current, so as to counteract the influence of the vertical component of the interfering magnetic field generated by the interfering current in the Rogowski coil 1122 on the Rogowski coil 1122.
[0067] For example, if n is 6, the arc detection board 112 further includes a top plate and a bottom plate, with a first layer, a third layer, a fourth layer, and a second layer stacked sequentially between the top and bottom plates. Both the top and bottom plates are coated with copper for shielding. The first and second layers serve as the wiring layers for the Rogowski coil 1122, and the third and fourth layers serve as the wiring layers for the two return wires of the Rogowski coil 1122. Obviously, this arrangement allows the two return wires of the Rogowski coil 1122 to be located in the central layer of the arc detection board 112 with a 6-layer structure, thereby minimizing the influence of the vertical component of the interfering magnetic field on the Rogowski coil 1122.
[0068] Furthermore, to ensure more reliable arc detection results, the power conversion device 11 is also equipped with a self-test winding. During each power-on process, the power conversion device 11 will use the self-test winding to determine whether the arc fault detection function of the power conversion device 11 is normal.
[0069] Specifically, as shown in Figure 7, the arc detection plate 112 further includes a second through hole 1124, and the power conversion device 11 further includes a self-test winding 1125. The second through hole 1124 penetrates the arc detection plate 112 along its thickness direction. The second through hole 1124 is located between the first through hole 1121 and the Rogowski coil 1122, and the distance between the second through hole 1124 and the first through hole 1121 is greater than the safety distance. The self-test winding 1125 is laid (e.g., printed) on the arc detection plate 112 and passes through the second through hole 1124. The self-test winding 1125 is located outside the wiring area of the Rogowski coil 1122.
[0070] Before the power conversion circuit 1111 starts working, the controller 1112 outputs an AC current (i.e., a high-frequency PWM signal) to the self-test winding 1125. The Rogowski coil 1122 senses the AC current flowing through the self-test winding 1125 and generates a proportional AC voltage, i.e., a self-test induction signal. Then, the signal conditioning circuit 1123 filters and amplifies the self-test induction signal to generate a self-test detection signal. If the sum of the gains of the self-test detection signal after fast Fourier transform within a preset frequency band is greater than a threshold, it indicates that an electric arc exists on the self-test winding, meaning the arc fault detection function of the power conversion device 11 is normal, and the controller then starts the power conversion circuit 1111 to operate.
[0071] Furthermore, the power board 111 and the arc detection board 112 can be configured such that the arc detection board 112 is perpendicularly disposed on the surface of the power board 111: As shown in Figure 7, the edge of the arc detection board 112 includes conductive protrusions 1126 and 1127, and the signal conditioning circuit 1123 is conductively connected to the conductive protrusions 1126 and 1127. The power board 111 includes two conductive holes (not shown), and the conductive protrusions 1126 and 1127 are respectively inserted into the two conductive holes, realizing the conductive connection between the two conductive protrusions and the two conductive holes. In summary, the power board 111 and the arc detection board 112 can realize the signal transmission function through the conductive connection between the conductive holes and the conductive protrusions. The arc detection signal or self-test detection signal generated by the signal conditioning circuit 1123 in the arc detection board 112 can be transmitted to the controller 1112 in the power board 111 through the conductive path between the conductive holes and the conductive protrusions. In summary, in this application, the connection between the conductive protrusion and the conductive hole not only enables the fixed connection between the power board 111 and the arc detection board 112, but also enables the signal connection between the signal conditioning circuit 1123 and the controller 1112.
[0072] In practical applications, the conductive bump can specifically be a solder finger. After the conductive bump is inserted into the conductive hole, a reliable connection between the conductive bump and the conductive hole can be achieved by soldering. Furthermore, the conductive hole can be a metallized hole, or a through-hole or blind hole with conductive material on its inner wall. In specific configurations, the specific structural shapes of the conductive hole and conductive bump can be flexibly adjusted according to actual needs, and this application does not impose any limitations on this.
[0073] Furthermore, the way the first connecting wire segment passes through the first through hole along the thickness direction of the arc detection plate 112 in this application is illustrated by the arched first connecting wire segment a1 in Figure 5a. In practical applications, the first connecting wire segment can also pass through the first through hole in a semi-rectangular shape along the thickness direction of the arc detection plate 112; this application does not limit this. The extension direction of the second and third connecting wire segments along the thickness direction of the power plate in this application is illustrated by the direction perpendicular to the power plate 111 as shown in Figure 5a. In practical applications, directions within a certain angular error (e.g., 27 degrees) from the direction perpendicular to the power plate 111 also belong to the aforementioned extension directions. In addition, the shape and size of the first through hole to the second through hole, and the first via hole to the fourth via hole in this application can be reasonably set according to actual needs; this application does not limit this.
[0074] In this application, the Rogowski coil 1122 laid on the arc detection board 112 can be understood as a PCB Rogowski coil. The power conversion device performs arc fault detection through the PCB Rogowski coil. Since the PCB Rogowski coil is printed on the PCB and is an air-core coil, it obviously does not contain an iron core. Therefore, the size of the power conversion device can be reduced, thereby effectively reducing the cost of the power conversion device. In addition, the mutual inductance coefficient M of the PCB Rogowski coil is related to the structural parameters of the coil body, such as the number of turns, board thickness, inner diameter, and outer diameter. The PCB Rogowski coil for arc fault detection provided in this application is a closed structure or a near-closed structure. For a closed or near-closed PCB Rogowski coil, the position of the tested conductor has almost no effect on the mutual inductance value, that is, the output voltage is not affected by the distance of the tested conductor from the center of the PCB Rogowski coil. When the conductor being measured deviates from the center of the PCB Rogowski coil, the magnetic flux of each turn of the coil changes compared to the ideal case where no deviation occurs. However, the magnetic flux increases on the side closer to the measured current and decreases on the side farther from the measured current, and the total magnetic flux remains almost unchanged. Therefore, this application does not require special settings for the distance between the connecting wire and the center of the PCB Rogowski coil, which can still ensure the accuracy of the induced electromotive force generated by the PCB Rogowski coil, thereby achieving reliable arc detection.
[0075] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A power conversion device, characterized in that, The power conversion device includes a power board and an arc detection board, wherein the arc detection board is vertically disposed on the surface of the power board, wherein: The arc detection plate includes a first through hole, which penetrates the arc detection plate along its thickness direction, and a Rogowski coil is laid around the first through hole on the arc detection plate. The power board is provided with a power conversion circuit, and the connecting wire between the power conversion circuit and the DC input of the power conversion device includes a U-shaped wire. The U-shaped wire passes through the first through hole along the thickness direction of the arc detection plate, and the two sides of the U-shaped wire are respectively located on both sides of the arc detection plate. The Rogowski coil is used to sense the alternating current on the connecting wire and generate an arc induction signal for arc fault detection in the power conversion device.
2. The power conversion device according to claim 1, characterized in that, The arc detection plate includes a first layer plate and a second layer plate stacked together, and a plurality of through holes surrounding the first through hole and penetrating the first layer plate and the second layer plate along the thickness direction of the arc detection plate. Each of the multiple sets of vias includes a conductive first via, a second via, a third via, and a fourth via. The first via and the second via are located on the same side of the straight line where the third via and the fourth via are located, and the first via and the fourth via are located on the same side of the straight line where the second via and the third via are located. The Rogowski coil includes a conductive coating applied to the inner wall of each via in each group of vias, a first connecting wire between the first and second vias in each group of vias, a second connecting wire between the third and fourth vias, a third connecting wire between the second and fourth vias, and a fourth connecting wire between the first via of one group of vias and the third via of the other group of vias in any two adjacent groups of vias. The first and second connecting wires are printed on the first layer, and the third and fourth connecting wires are printed on the second layer.
3. The power conversion device according to claim 2, characterized in that, If the number of layers of the arc detection plate is odd, then the arc detection plate also includes a third layer plate, which is located between the first layer plate and the second layer plate. The multiple sets of vias also penetrate the third layer plate along the thickness direction of the arc detection plate. The power conversion device also includes a return wire of the Rogowski coil, which is printed on the third layer plate. After the return wire is connected to one end of the Rogowski coil, it passes through the channel formed by the Rogowski coil and the arc detection plate to generate an induced electromotive force on the return wire that is opposite in direction to the induced electromotive force generated by the Rogowski coil inducing the ripple current in the connecting wire.
4. The power conversion device according to claim 2, characterized in that, If the number of layers of the arc detection plate is even, the arc detection plate further includes a third layer plate and a fourth layer plate stacked together. The third layer plate and the fourth layer plate are located between the first layer plate and the second layer plate. The multiple sets of vias also penetrate the third layer plate and the fourth layer plate along the thickness direction of the arc detection plate. The power conversion device also includes two return wires of the Rogowski coil, which are printed on the third and fourth layers respectively. Each of the two return wires is connected to one end of the Rogowski coil and then passes through the channel formed by the Rogowski coil and the arc detection plate to generate an induced electromotive force on the two return wires in the opposite direction to the induced electromotive force generated by the ripple current in the connecting wire induced by the Rogowski coil.
5. The power conversion device according to any one of claims 1-4, characterized in that, The gap formed by the Rogowski coil surrounding the first through hole is smaller than the diameter of the first through hole.
6. The power conversion device according to any one of claims 1-5, characterized in that, The U-shaped conductor is a copper busbar.
7. The power conversion device according to any one of claims 1-6, characterized in that, The power conversion device further includes a signal conditioning circuit and a controller, wherein: The signal conditioning circuit is connected to the Rogowski coil and is used to filter and amplify the arc induction signal to generate an arc detection signal. The controller is used to shut down the power conversion device when the sum of the gains of the arc detection signal after fast Fourier transform within a preset frequency band is greater than a threshold.
8. The power conversion device according to claim 7, characterized in that, The power conversion device further includes a self-test winding, wherein: The controller is also configured to output AC current to the self-test winding before the power conversion circuit starts working; The Rogowski coil is also used to sense the alternating current flowing through the self-test winding and to generate a self-test induction signal; The signal conditioning circuit is also used to filter and amplify the self-test sensing signal to generate a self-test detection signal; The controller is also used to control the power conversion circuit to start working when the sum of the gains of the self-test detection signal after fast Fourier transform within the preset frequency band is greater than the threshold.
9. The power conversion device according to claim 8, characterized in that, The arc detection plate also includes a second through hole, which penetrates the arc detection plate along its thickness direction. The second through hole is located between the first through hole and the Rogowski coil, and the distance between the second through hole and the first through hole is greater than the safety distance. The self-test winding is laid on the arc detection plate and passes through the second through hole.
10. The power conversion device according to any one of claims 7-9, characterized in that, The signal conditioning circuit is disposed on the surface of the arc detection board and is located around the Rogowski coil.
11. The power conversion device according to any one of claims 1-10, characterized in that, The arc detection plate includes a plurality of first through holes, the Rogowski coil surrounds the plurality of first through holes, the plurality of first through holes correspond one-to-one with a plurality of connecting wires between the power conversion circuit and the DC input of the power conversion device, a U-shaped wire in one of the connecting wires passes through a first through hole along the thickness direction of the arc detection plate, and the two sides of the U-shaped wire in one of the connecting wires are respectively located on both sides of the arc detection plate.
12. A power generation system, characterized in that, The power generation system includes a power conversion device and photovoltaic modules or energy storage batteries. The DC input of the power conversion device is connected to the photovoltaic modules or energy storage batteries, wherein: The power conversion device includes a power board and an arc detection board, wherein the arc detection board is vertically disposed on the surface of the power board; The arc detection plate includes a first through hole, which penetrates the arc detection plate along its thickness direction, and a Rogowski coil is laid around the first through hole on the arc detection plate. The power board is provided with a power conversion circuit, and the connecting wire between the power conversion circuit and the DC input of the power conversion device includes a U-shaped wire. The U-shaped wire passes through the first through hole along the thickness direction of the arc detection plate, and the two sides of the U-shaped wire are respectively located on both sides of the arc detection plate. The Rogowski coil is used to sense the alternating current on the connecting wire and generate an arc induction signal for arc fault detection in the power conversion device.