Inverter

Abstract

This application provides an inverter, which includes an input terminal, a DC switch, multiple DC / DC converters, a DC bus, a DC / AC converter, a controller, and an output terminal. The DC switch includes an operating handle, an operating mechanism, a moving contact, a stationary contact, and a first drive device. The operating mechanism includes a tripping component and a locking component. The input terminals of the multiple DC / DC converters are connected to the input terminal of the inverter via the DC switch. In the event of an inverter fault, the controller sends a first drive signal to the first drive device. Upon receiving the first drive signal, the first drive device drives its moving component to disengage the locking component from the tripping component, thus separating the moving contact from the stationary contact. With the tripping component and locking component disengaged, the operating handle cannot drive the moving contact to contact or separate from the stationary contact. This prevents the DC switch from being manually closed while the inverter fault persists, thus avoiding the spread of the fault.

Description

Technical Field

[0001] This application relates to the field of power supply technology, and more particularly to an inverter. Background Technology

[0002] With the continuous increase in photovoltaic installations, photovoltaic inverters have become the mainstream power generation equipment in the photovoltaic industry. In order to ensure the stable operation of the power generation system in which the photovoltaic inverter is located, the photovoltaic inverter needs to prevent the fault from spreading when an internal fault occurs.

[0003] Currently, Figure 1 When a fault occurs inside the photovoltaic inverter (such as a short circuit in the DC bus BUS+, BUS-, or the internal power transistor), the controller sends a voltage drive signal to the flux of the DC switch S1, causing the DC switch S1 to open. The connection between the photovoltaic inverter and the photovoltaic string is then disconnected, thereby achieving fault isolation.

[0004] For the above fault isolation scheme, even if the internal fault of the inverter is not eliminated after the DC switch S1 is successfully tripped, the maintenance personnel can still close the DC switch S1 again by operating the operating handle of the DC switch S1, thereby amplifying the inverter fault. Summary of the Invention

[0005] This application provides an inverter that can prevent the DC switch from being manually closed and causing the fault to spread when an internal fault still exists in the inverter.

[0006] In a first aspect, this application provides an inverter comprising an input terminal, a DC switch, multiple DC / DC converters, a DC bus, a DC / AC converter, a controller, and an output terminal. The input terminal is used to connect to a photovoltaic string, and the output terminal is used to connect to the AC power grid. The DC switch includes an operating handle, an operating mechanism, a moving contact, a stationary contact, a first drive device, and a second drive device. The input terminals of the multiple DC / DC converters are connected to the input terminal of the inverter via the DC switch, and the output terminals of the multiple DC / DC converters are connected in parallel to the DC bus. The input terminals of the DC / AC converters are connected to the DC bus, and the output terminals of the DC / AC converters are connected to the output terminal of the inverter. The operating mechanism includes a locking component, a tripping component, a transmission assembly, and a reset component. The operating handle, tripping component, reset component, and moving contact are all connected to the transmission assembly. The operating mechanism is used to drive the moving contact and the stationary contact to contact and separate. When the tripping component and the locking component are engaged, the operating handle can drive the transmission assembly to drive the moving contact and the stationary contact to contact and separate. When the tripping component and the locking component are disengaged, the operating handle cannot drive the transmission assembly to drive the moving contact and the stationary contact to contact and separate. The controller is used to send a first drive signal to the first drive device in the event of an inverter failure. Upon receiving the first drive signal, the first drive device drives its moving component to move, thereby disengaging the locking component and the tripping component, thus causing the transmission assembly to separate the moving contact and the stationary contact. After the first drive device separates the moving contact and the stationary contact, the operating handle is used to prevent the moving component in the first drive device from resetting under external force. The controller is also used to send a second drive signal to the second drive device in the event of a failure in the photovoltaic string or its connecting lines. The second driving device, upon receiving a second driving signal, drives the moving component within it to disengage the locking component from the tripping component, thereby causing the transmission assembly to separate the moving contact from the stationary contact. After the second driving device separates the moving contact from the stationary contact, the operating handle, under external force, drives the transmission assembly to move the reset component, resetting the moving component in the second driving device. After the moving component in the second driving device resets, the operating handle, under external force, also drives the tripping component to engage with the locking component, enabling the operating handle to drive the transmission assembly to contact the moving contact with the stationary contact.

[0007] In this embodiment, when the inverter malfunctions, since the operating handle cannot be driven to reset the moving parts in the first drive device under external force after the DC switch is opened, the situation where the DC switch is manually closed while the internal fault of the inverter still exists, thus preventing the fault from spreading, can be avoided. Furthermore, in the case of a fault in the photovoltaic string or its connecting lines, since the operating handle can be driven to close the DC switch under external force after the DC switch is opened, the debugging needs of maintenance personnel when troubleshooting faults in the photovoltaic string or its connecting lines can be met.

[0008] In conjunction with the first aspect, in a first possible implementation, the controller is specifically configured to: send a second drive signal to the second drive device if the number of times the second drive signal is sent to the second drive device does not exceed a preset threshold when a fault occurs in the photovoltaic string or its connection line; the controller is also configured to: send a first drive signal to the first drive device when a fault occurs in the photovoltaic string or its connection line, if the number of times the second drive signal is sent to the second drive device exceeds the preset threshold.

[0009] In this embodiment, after the DC switch is tripped due to a fault in the photovoltaic string or its connecting line, the DC switch can be manually closed within a preset number of times. This not only meets the debugging needs of maintenance personnel when troubleshooting faults in the photovoltaic string or its connecting line, but also effectively prevents the spread of the fault.

[0010] In conjunction with the first aspect or the first possible implementation of the first aspect, in a second possible implementation, the controller is further configured to send a third drive signal to the first drive unit when the inverter fault is cleared. The first drive unit is further configured to reset its moving component upon receiving the third drive signal. After the moving component in the first drive unit is reset, the operating handle, under external force, drives the trip latch component to engage with the locking component, thereby enabling the operating handle to drive the transmission assembly to bring the moving contact into contact with the stationary contact.

[0011] In this embodiment, the inverter controls the moving parts in the first drive device to reset after its own fault is eliminated, thereby ensuring that the DC switch can be manually closed after the inverter fault is eliminated, so as to meet the maintenance or debugging needs of maintenance personnel for the inverter.

[0012] In conjunction with any of the first to second possible implementations of the first aspect, in a third possible implementation, the controller is further configured to determine that the inverter has malfunctioned when the electrical parameters of the inverter exceed the range of the first preset parameters, wherein the electrical parameters of the inverter include the bus voltage value or the bus current value of the DC bus.

[0013] In this embodiment, the inverter can determine whether it has experienced a fault based on the bus voltage value or the bus current value. The fault detection methods are diverse and highly flexible.

[0014] In conjunction with any of the first to third possible embodiments of the first aspect, in a fourth possible embodiment, the controller is further configured to determine that a fault has occurred in the photovoltaic string or its connecting lines when the electrical parameters of the photovoltaic string exceed the range of the second preset parameters, wherein the electrical parameters of the photovoltaic string include the output voltage value, the output current value, or the insulation resistance to ground value.

[0015] In this embodiment, the inverter can determine whether the photovoltaic string or its connecting lines are faulty based on the output voltage value, output current value, or insulation resistance value to ground of the photovoltaic string. The fault detection methods are diverse and highly flexible.

[0016] Secondly, this application provides an inverter comprising an input terminal, a DC switch, multiple DC / DC converters, a DC bus, a DC / AC converter, a controller, and an output terminal. The input terminal is used to connect to a photovoltaic string, and the output terminal is used to connect to the AC power grid. The DC switch includes an operating handle, an operating mechanism, a moving contact, a stationary contact, and a first drive device. The input terminals of the multiple DC / DC converters are connected to the input terminal of the inverter via the DC switch, and the output terminals of the multiple DC / DC converters are connected in parallel to the DC bus. The input terminals of the DC / AC converters are connected to the DC bus, and the output terminals of the DC / AC converters are connected to the output terminal of the inverter. The operating mechanism includes a locking component, a tripping component, a transmission assembly, and a reset component. The operating handle, tripping component, reset component, and moving contact are all connected to the transmission assembly. The operating mechanism is used to drive the moving contact to contact and separate from the stationary contact. When the tripping component and locking component are engaged, the operating handle can drive the transmission assembly to drive the moving contact to contact and separate from the stationary contact. When the tripping component and locking component are disengaged, the operating handle cannot drive the transmission assembly to drive the moving contact to contact and separate from the stationary contact. The controller is used to send a first drive signal to the first drive device in the event of a fault in the inverter, photovoltaic string, or the photovoltaic string's connection line. The first drive device is configured to drive the moving part in the first drive device to move when a first drive signal is received, so as to drive the locking part to disengage from the tripping part and cause the transmission assembly to drive the moving contact to separate from the stationary contact; the controller is also configured to send a third drive signal to the first drive device when the inverter fault is cleared; and to send a third drive signal to the first drive device before the photovoltaic string or its connection line fault is cleared and the moving contact is separated from the stationary contact; the first drive device is also configured to drive the moving part in the first drive device to reset when the third drive signal is received; after the moving part in the first drive device is reset, the operating handle is also configured to drive the tripping part to engage with the locking part when subjected to external force, so that the operating handle can drive the transmission assembly to drive the moving contact to contact the stationary contact.

[0017] In this embodiment, when an inverter malfunctions, since the operating handle cannot drive the moving parts in the first drive device to reset under external force after the DC switch is opened, the situation where the DC switch is manually closed while the internal fault of the inverter still exists, thus preventing the fault from spreading, can be avoided. Furthermore, in the case of a fault in the photovoltaic string or its connecting lines, after the DC switch is opened, the inverter immediately controls the moving parts in the first drive device to reset, and then the operating handle can drive the DC switch to close under external force. Therefore, this meets the debugging needs of maintenance personnel when troubleshooting photovoltaic string or its connecting lines. Additionally, the inverter controls the resetting of the moving parts in the first drive device after its own fault has been cleared, thereby ensuring that the DC switch can be manually closed after the inverter fault has been cleared.

[0018] In conjunction with the second aspect, in the first possible implementation, the controller is specifically configured to: send a third driving signal to the first driving device if the number of times a third driving signal is sent to the first driving device does not exceed a preset threshold before the photovoltaic string or its connecting line is cleared and the moving contact is separated from the stationary contact; the controller is also configured to: stop sending the third driving signal to the first driving device if the number of times a third driving signal is sent to the second driving device exceeds a preset threshold when the photovoltaic string or its connecting line fails.

[0019] In this embodiment, after the DC switch is tripped due to a fault in the photovoltaic string or its connecting line, the DC switch can be manually closed within a preset number of times. This not only meets the debugging needs of maintenance personnel when troubleshooting faults in the photovoltaic string or its connecting line, but also effectively prevents the spread of the fault.

[0020] In conjunction with any of the second aspect to the second possible implementation, in the fourth possible implementation, the controller is further configured to determine that the inverter has malfunctioned when the electrical parameters of the inverter exceed the range of the first preset parameters, wherein the electrical parameters of the inverter include the bus voltage value or the bus current value of the DC bus.

[0021] In this embodiment, the inverter can determine whether it has experienced a fault based on the bus voltage value or the bus current value. The fault detection methods are diverse and highly flexible.

[0022] In conjunction with any of the second to third possible implementations of the second aspect, in the fifth possible implementation, the controller is further configured to determine that a fault has occurred in the photovoltaic string or its connecting lines when the electrical parameters of the photovoltaic string exceed the range of the second preset parameters, wherein the electrical parameters of the photovoltaic string include the output voltage value, the output current value, or the insulation resistance to ground value.

[0023] In this embodiment, the inverter can determine whether the photovoltaic string or its connecting lines are faulty based on the output voltage value, output current value, or insulation resistance value to ground of the photovoltaic string. The fault detection methods are diverse and highly flexible. Attached Figure Description

[0024] Figure 1 This is a structural schematic diagram of a photovoltaic inverter provided by existing technology;

[0025] Figure 2 This is a schematic diagram illustrating the application scenario of the inverter provided in this application;

[0026] Figure 3 This is a structural schematic diagram of the inverter provided in this application;

[0027] Figure 4 This is a schematic diagram of a DC switch provided in this application;

[0028] Figure 5 This is another schematic diagram of the DC switch provided in this application;

[0029] Figure 6 This is another schematic diagram of the DC switch provided in this application;

[0030] Figure 7 This is another schematic diagram of the DC switch provided in this application;

[0031] Figure 8 This is another schematic diagram of the DC switch provided in this application;

[0032] Figure 9 This is another schematic diagram of the DC switch provided in this application;

[0033] Figure 10 This is another structural schematic diagram of the inverter provided in this application;

[0034] Figure 11 This is another schematic diagram of the DC switch provided in this application;

[0035] Figure 12 This is another schematic diagram of the DC switch provided in this application;

[0036] Figure 13 This is another schematic diagram of the DC switch provided in this application;

[0037] Figure 14 This is another schematic diagram of the DC switch provided in this application. Detailed Implementation

[0038] The inverter provided in this application is applicable to various fields, including photovoltaic power generation, photovoltaic-storage hybrid power generation, new energy smart microgrids, and power transmission and distribution. It is suitable for different application scenarios, such as photovoltaic power supply scenarios, photovoltaic-storage hybrid power supply scenarios, and UPS power supply scenarios. The following explanation uses a photovoltaic power supply scenario as an example.

[0039] See Figure 2 , Figure 2 This is a schematic diagram illustrating the application scenario of the inverter provided in this application. For example... Figure 2As shown, inverter 1 includes an input terminal, a DC switch S1, DC / DC converters 111, ..., DC / DC converters 11n, DC buses (including a positive DC bus BUS+ and a negative DC bus BUS-), a DC / AC converter 12, a controller 13, and an output terminal. The DC switch S1 includes an operating handle, an operating mechanism, a moving contact, a stationary contact, a first drive device, and a second drive device. The operating mechanism includes a tripping component and a locking component, where n is an integer greater than 1. The operating mechanism includes a locking component, a tripping component, a transmission assembly, and a reset component; the operating handle, tripping component, reset component, and moving contact are all connected to the transmission assembly. The operating mechanism is used to drive the moving contact to contact and separate from the stationary contact. When the tripping component and the locking component are engaged, the operating handle can drive the transmission assembly to drive the moving contact to contact and separate from the stationary contact; when the tripping component and the locking component are disengaged, the operating handle cannot drive the transmission assembly to drive the moving contact to contact and separate from the stationary contact.

[0040] The input terminal of inverter 1 is connected to a photovoltaic string (at least one photovoltaic module connected in series and parallel), and the output terminal of inverter 1 is connected to the AC grid or a load (such as household appliances). The input terminals of DC / DC converter 111, ..., and DC / DC converter 11n are all connected to the input terminal of inverter 1 via DC switch S1. The output terminals of DC / DC converter 111, ..., and DC / DC converter 11n are connected in parallel and then connected to the positive DC bus BUS+ and the negative DC bus BUS-, respectively. The input terminals of DC / AC converter 12 are connected to the positive DC bus BUS+ and the negative DC bus BUS-, respectively, and the output terminal of DC / AC converter 12 is connected to the output terminal of inverter 1.

[0041] After inverter 1 starts operating, i.e., after DC switch S1 is closed, controller 13 adjusts the output voltage of the photovoltaic strings connected to each of the n DC / DC converters to perform maximum power point tracking (MPPT) on the output power of the photovoltaic strings, maximizing the output power of the photovoltaic strings connected to each DC / DC converter. Simultaneously, controller 13 also controls each DC / DC converter to perform DC-DC conversion on the output voltage of its respective connected photovoltaic strings and outputs the converted DC voltage to the DC bus. Controller 13 further controls DC / AC converter 12 to invert the DC bus voltage at its input terminal into AC power, thereby enabling power supply to various types of electrical equipment, such as AC grids or loads.

[0042] The embodiments of this application mainly optimize the operation of DC switch S1 under fault scenarios in the above-described implementation scenarios.

[0043] Specifically, this application categorizes fault scenarios into two types. One type is faults in internal components or circuits of inverter 1. These faults require professional personnel to troubleshoot; otherwise, closing the DC switch S1 before troubleshooting will cause the fault to escalate further. The other type is external faults on the DC side of inverter 1, mainly faults in the photovoltaic string or its connecting lines. These faults are generally caused by manual reverse connection of the photovoltaic modules. Therefore, after manual troubleshooting, the DC switch S1 can be manually closed to start the normal operation of the inverter.

[0044] Based on the above fault classification and fault resolution ideas, this application embodiment designs an inverter whose controller 13 can classify the above two fault types. At the same time, the internal structure of the DC switch S1 is improved so that the DC switch S1 can achieve different effects under the control of the controller 13 under different fault types.

[0045] Specifically, after inverter 1 starts operating, if a fault is detected inside inverter 1, controller 13 sends a first drive signal to the first drive device. Upon receiving the first drive signal, the first drive device drives its moving component to move, thereby disengaging the latching component from the tripping component, thus separating the moving contact of DC switch S1 from the stationary contact, disconnecting the connection between inverter 1 and the photovoltaic string, and achieving fault isolation. In this embodiment, when a fault occurs inside inverter 1, after the first drive device drives the moving contact of DC switch S1 to separate from the stationary contact, the moving component continues to apply force to the latching component. Under external force, the operating handle cannot drive the moving component in the first drive device to reset, preventing the tripping component from engaging with the latching component, and thus the operating handle cannot drive DC switch S1 to close.

[0046] If a fault is detected in the photovoltaic string or its connecting lines (an external DC-side fault of the inverter), the controller 13 sends a second drive signal to the second drive device. Upon receiving the second drive signal, the second drive device drives its moving component to move, thereby disengaging the latching component from the tripping component. This separates the moving contact of the DC switch S1 from the stationary contact, disconnecting the inverter 1 from the photovoltaic string and achieving fault isolation. In this embodiment, when a fault occurs in the photovoltaic string or its connecting lines, after the second drive device drives the moving contact of the DC switch S1 to separate from the stationary contact, a reset component for the second drive device is provided in the DC switch S1. This allows the operating handle to be reset by the reset component when subjected to external force. The operating handle can then further drive the tripping component to engage, and the moving contact of the DC switch S1 to contact the stationary contact, thus closing the DC switch S1.

[0047] Understandably, in the event of a fault in inverter 1, after the DC switch S1 is tripped, the operating handle, under external force, cannot drive the moving parts in the first drive device to reset. Consequently, the locking and tripping parts remain disengaged and remain in the disengaged state. Therefore, this prevents the DC switch S1 from being manually closed and causing the fault to spread if the internal fault of inverter 1 still exists. Furthermore, in the event of a fault in the photovoltaic string or its connecting lines, the presence of a reset component for the second drive device allows the operating handle, under external force, to reset the moving parts of the second drive device after the DC switch is tripped. This enables the tripping parts to engage and the DC switch S1 to close. Therefore, this meets the debugging needs of maintenance personnel when troubleshooting photovoltaic strings or their connecting lines.

[0048] The above are merely examples of application scenarios for the inverter provided in this application, and are not exhaustive. This application does not limit the application scenarios.

[0049] The following is combined with Figures 3 to 14 The working principle of the inverter provided in this application is illustrated by an example.

[0050] See Figure 3 , Figure 3 This is a structural schematic diagram of the inverter provided in this application. Figure 3 As shown, inverter 1 includes input terminals (i.e., input terminals i11+, i11-, i12+, i12-, ..., i1n1+, i1n1-, i1n2+, and i1n2-), a DC switch S1, DC / DC converters 111, ..., DC / DC converters 11n, DC buses (including positive DC bus BUS+ and negative DC bus BUS-), a DC / AC converter 12, a controller 13, and output terminals (o11 and o12). The DC switch S1 includes an operating handle, an operating mechanism, a moving contact, a stationary contact, a first drive device, and a second drive device. The operating mechanism includes a tripping component and a locking component. n is an integer greater than 1. The input terminals of inverter 1 are used to connect to photovoltaic strings, and the output terminals o11 and o12 of inverter 1 are used to connect to the AC power grid. The input terminals of the aforementioned n DC / DC converters are connected to the input terminal of inverter 1 via DC switch S1. The output terminals of the aforementioned n DC / DC converters are connected in parallel and then connected to the positive DC bus BUS+ and the negative DC bus BUS-, respectively. The input terminals of DC / AC converter 12 are connected to the positive DC bus BUS+ and the negative DC bus BUS-, respectively. The output terminals of DC / AC converter 12 are connected to the output terminals o11 and o12 of inverter 1, respectively.

[0051] In one implementation scenario, during the process of inverter 1 supplying power to the AC grid, if inverter 1 malfunctions, controller 13 sends a first drive signal to the first drive device. Upon receiving the first drive signal, the first drive device drives its moving component to disengage the locking component from the tripping component, thereby separating the moving contact from the stationary contact of DC switch S1, i.e., opening DC switch S1. After DC switch S1 is opened, the operating handle, under external force, cannot drive the moving component in the first drive device to reset, thus preventing the tripping component from engaging with the locking component, and consequently preventing the moving contact from contacting the stationary contact of DC switch S1.

[0052] In one possible implementation, if the inverter 1 fault is detected and resolved, the controller 13 may send a third drive signal to the first drive unit. Upon receiving the third drive signal, the first drive unit resets its moving component. After the moving component in the first drive unit is reset, the operating handle, under external force, drives the trip latch component to engage with the locking component, and drives the moving contact of the DC switch S1 to contact the stationary contact.

[0053] The first driving device can be a control device capable of enabling the moving part to reciprocate between two positions, such as a trip unit or a motor. For example, the first driving device is a bistable trip unit, and the moving part in the first driving device is a component that can be driven by a magnetic field to move between two steady-state positions. The second driving device can be a control device capable of enabling the moving part to move to at least one position, such as a trip unit or a motor. For example, the first driving device is a trip unit, and the moving part in the first driving device is a moving part. Of course, the second driving device can also be a bistable trip unit.

[0054] For ease of understanding, the following example assumes that both the first and second drive devices are trip units. Figures 4 to 7 The schematic diagram of DC switch S1 shown is used as an example for illustration. (Combined with...) Figures 4 to 7The DC switch S1 includes an operating handle Lf, a moving contact K1, a stationary contact K2, a trip unit TX1, a trip unit TX2, and an operating mechanism. The operating mechanism includes a transmission assembly, a locking component, a tripping component, and a reset component. For example, the transmission assembly may include linkage structures OA, AB, BC, GJ, and GE, and an elastic element GB. The reset component is EKF, the tripping component is DCH, and the locking component is M. Linkage structures OA, AB, and BC form a linkage structure OABC, and linkage structures GJ and GE form a linkage structure GJE. O, D, f, J, K, and Y all represent fixed hinge points. d1 represents the moving component in trip unit TX1, and d2 represents the moving component in trip unit TX2. The linkage structures EK and KF in the reset component EKF are rigidly coupled, and they rotate synchronously around point K.

[0055] It should be noted that in the embodiments of this application, the reset component EKF is only connected to the second drive device (trip unit TX2) and has no connection to the first drive device (trip unit TX1). That is to say, by controlling the reset attachment EKF, the moving part d2 of the trip unit TX2 can be reset, but the moving part d1 of the trip unit TX1 cannot be reset.

[0056] During the process of inverter 1 supplying power to the AC grid, DC switch S1 is in the closed state, corresponding to... Figure 4 The switch status is shown. (For example...) Figure 4 As shown, the latching component M is engaged with the tripping component DCH, and the moving contact K1 and the stationary contact K2 are in contact. The current position of the moving component d1 is x1 (first position), and the current position of the moving component d2 is x1' (third position). The controller 13 determines that the inverter 1 has malfunctioned if the electrical parameters of the inverter 1 exceed the range of the first preset parameters. The electrical parameters of the inverter 1 include the bus voltage or bus current value of the DC bus.

[0057] For example, the electrical parameter of inverter 1 is the bus voltage value of the DC bus, and the first preset parameter range is greater than a first voltage value. If the bus voltage value of the DC bus is less than or equal to the first voltage value, the controller 13 indicates that a short circuit has occurred on the DC bus, and thus determines that inverter 1 has malfunctioned.

[0058] For example, the electrical parameter of inverter 1 is the bus current value of the DC bus, and the first preset parameter range is less than a first current value. If the bus current value of the DC bus is greater than or equal to the first current value, the controller 13 indicates that a short circuit has occurred on the DC bus, and thus determines that inverter 1 has malfunctioned.

[0059] In the event of a fault in inverter 1, controller 13 sends a first drive signal (such as a positive pulse) to trip unit TX1. Then, as... Figure 5 As shown, when the trip unit TX1 receives the first drive signal, it drives the moving part d1 to move from position x1 to position x2 (the second position), that is... Figure 5 The position of the moving component d1 causes the locking component M to rotate clockwise around point Y, disengaging the locking component M from the tripping component DCH, which then rotates counterclockwise. Driven by the elastic potential energy stored in the elastic element GB, point B moves to the right, causing the moving contact K1 to rotate rapidly clockwise under the pull of the linkage mechanism AB. This separates the moving contact K1 from the stationary contact K2, allowing the DC switch S1 to open. Because the operating mechanism of DC switch S1 does not have a reset component for the moving part d1 of trip unit TX1, and the reset component EKF only serves as the reset component for the moving part d2 of trip unit TX2, after DC switch S1 is tripped, even if the maintenance personnel manually push the operating handle Lf clockwise to rotate point E clockwise, thereby rotating the linkage structure KF clockwise to perform the moving part reset operation, it is impossible to drive the moving part d1 to reset (i.e., drive the moving part d1 from position x2 back to position x1) by operating the operating handle of DC switch S1. The moving part d1 will always be in position x2, which means that the tripping component DCH and the locking component M cannot be engaged by operating the operating handle of DC switch S1, and therefore DC switch S1 cannot be closed by operating the operating handle of DC switch S1.

[0060] In the above situation, after the DC switch S1 is tripped, maintenance is required by a professional. After maintenance, the controller 13 can detect the electrical parameters of the inverter 1. If the electrical parameters of the inverter 1 are within the first preset parameter range, it indicates that the fault of the inverter 1 has been eliminated. Then, the controller 13 sends a third drive signal (such as a reverse pulse) to the trip unit TX1. When the trip unit TX1 receives the third drive signal, it drives the moving part d1 from position x2 to position x1 to reset the moving part d1. The latching part M rotates counterclockwise due to the reset of the moving part d1 and stops at... Figure 6 The position is shown. Since the moving part d1 has been reset, the maintenance personnel can push the operating handle Lf clockwise, which in turn pushes the trip latch component DCH clockwise. The locking part M is then engaged by the trip latch component DCH, meaning the locking part M and the trip latch component DCH are locked together. Figure 7The position is shown. Afterwards, the maintenance personnel rotate the operating handle Lf counterclockwise, causing the tension of the elastic element GB to extend beyond the left side of the connecting rod structure BC. Point B moves to the left under the tension of the elastic element GB, and the connecting rod structure AB pushes the moving contact K1 downward to close, thus putting the moving contact K1 and the stationary contact K2 in a closed state. Figure 4 As shown in the switch state, DC switch S1 has completed closing.

[0061] Understandably, in the event of a fault in inverter 1, controller 13 controls the DC switch S1 to open by driving the moving parts in the first drive unit. Since DC switch S1 does not have a reset component for the moving parts in the first drive unit, maintenance personnel cannot close DC switch S1 by operating its handle. Only after controller 13 detects that the fault in inverter 1 has been cleared, and resets the moving parts in the first drive unit, can maintenance personnel close DC switch S1 by operating its handle. This ensures that when inverter 1 malfunctions, maintenance personnel cannot close DC switch S1 by operating its handle before the fault is cleared. Professional repair is required, and the inverter's internal controller 13 must verify the repair before closing the switch, thus guaranteeing the safety of maintenance personnel.

[0062] In another implementation scenario, during the process of inverter 1 supplying power to the AC grid, if a fault occurs in the photovoltaic string or its connecting line (an external inverter fault), controller 13 sends a second drive signal to the second drive device. Upon receiving the second drive signal, the second drive device drives its moving component to disengage the locking component from the tripping component, thereby separating the moving contact of DC switch S1 from the stationary contact, i.e., opening DC switch S1. After DC switch S1 is opened, the operating handle, under external force, drives the moving component in the second drive device to reset via the reset component, causing the tripping component to engage with the locking component, and driving the moving contact of DC switch S1 to contact the stationary contact. The second drive device can be a device capable of unidirectional motion control, such as a trip unit or a motor.

[0063] To facilitate understanding, we will again use the example where both the first and second drive devices are trip units, combined with... Figure 4 , Figures 8 to 9 The schematic diagram of DC switch S1 shown is used as an example for illustration.

[0064] During the process of inverter 1 supplying power to the AC grid, DC switch S1 is in the closed state, corresponding to... Figure 4 The switch status is shown. (For example...) Figure 4As shown, the current position of moving part d1 is x1, and the current position of moving part d2 is x1'. When the electrical parameters of the photovoltaic string exceed the range of the second preset parameters, the controller 13 determines that a fault has occurred in the photovoltaic string or its connecting lines. The electrical parameters of the photovoltaic string include the output voltage value, output current value, or ground insulation impedance value of the photovoltaic string.

[0065] For example, the electrical parameter of the photovoltaic string is the reverse output current value, and the second preset parameter range is less than or equal to the second current value. If the reverse output current value of the photovoltaic string is greater than the second current value, the controller 13 indicates that the photovoltaic string connected to the input terminal of the inverter 1 is in a reverse connection or short circuit condition, and thus determines that the photovoltaic string or its connecting lines have failed. The second current value can be determined according to actual conditions, and this application does not impose specific restrictions on it. Preferably, in order to detect the fault as early as possible and trigger the protection action of the DC switch S1 in a timely manner, the second current value can be a small value, such as 0.

[0066] For example, the electrical parameter of the photovoltaic string is the output voltage value, and the second preset parameter range is greater than the second voltage value. If the output voltage value of the photovoltaic string is less than or equal to the second voltage value, the controller 13 indicates that there is a short circuit in the photovoltaic string or its connection line connected to the input terminal of the inverter 1, and thus determines that the photovoltaic string or its connection line has failed.

[0067] For example, the electrical parameter of the photovoltaic string is its insulation resistance to ground, and the second preset parameter range is the safe range of the insulation resistance to ground when there is no electrical connection between the electrical equipment or line and the ground. If the insulation resistance to ground of the photovoltaic string exceeds the range of the second preset parameter, the controller 13 indicates that the connection line of the photovoltaic string is grounded, and thus determines that the photovoltaic string or its connection line has failed.

[0068] Subsequently, in the event of a fault in the photovoltaic string or its connecting lines, controller 13 sends a second drive signal to trip unit TX2. Then, as... Figure 8 As shown, when the trip unit TX2 receives the second drive signal, it drives the moving part d2 to move from position x1' to position x2' (the fourth position), that is... Figure 8 The position of the moving component d2 causes the locking component M to rotate clockwise around point Y, disengaging the locking component M from the tripping component DCH, which then rotates counterclockwise. Driven by the elastic potential energy stored in the elastic element GB, point B moves to the right, causing the moving contact K1 to rotate rapidly clockwise under the pull of the linkage mechanism AB. This separates the moving contact K1 from the stationary contact K2, allowing the DC switch S1 to open.

[0069] Because the DC switch S1 is equipped with a reset component for the moving part d2, after the DC switch S1 is tripped, maintenance personnel can manually push the operating handle Lf clockwise based on debugging needs (e.g., the maintenance personnel believe that the photovoltaic string or its connection line fault has been eliminated). This causes point E to rotate clockwise, which in turn causes the linkage structure KF to rotate clockwise, thereby driving the moving part d2 from position x2' back to position x1', thus resetting the moving part d2. The locking component M rotates counterclockwise due to the reset of the moving part d2 and stops at... Figure 9 The position is shown. After the moving part d2 is reset, the maintenance personnel can continue to push the operating handle Lf clockwise. The operating handle Lf pushes the trip latch part DCH clockwise, and the locking part M is engaged by the trip latch part DCH. That is, the locking part M and the trip latch part DCH are engaged. Figure 7 The position is shown. Afterwards, the maintenance personnel rotate the operating handle Lf counterclockwise, causing the tension of the elastic element GB to extend beyond the left side of the connecting rod structure BC. Point B moves to the left under the tension of the elastic element GB, and the connecting rod structure AB pushes the moving contact K1 downward to close, thus putting the moving contact K1 and the stationary contact K2 in a closed state. Figure 4 As shown in the switch state, DC switch S1 has completed closing.

[0070] Furthermore, to meet the debugging requirements of maintenance personnel to manually close the DC switch when troubleshooting photovoltaic strings and their connecting lines, while also preventing users from repeatedly closing the DC switch S1 directly before troubleshooting the photovoltaic strings and their connecting lines, the controller 13 starts counting the number of times the second drive signal is sent to the trip unit TX2 after a fault occurs in the photovoltaic string or its connecting lines. If the number of times the second drive signal is sent does not exceed a preset threshold, and if the maintenance personnel detect that the photovoltaic string or its connecting lines are still faulty after manually closing the switch, the second drive signal is sent again to open the DC switch S1, and manual closing is possible. If the number of times the second drive signal is sent exceeds the preset threshold, the second drive signal is stopped from being sent to the trip unit TX2, and the first drive signal is sent to the trip unit TX1 instead, thereby opening the DC switch S1 and preventing manual closing. Figure 5 The switch status is shown. For details, please refer to the control principle of the first drive signal above. The preset threshold is determined based on the number of times the DC switch can be safely disconnected, with a margin allowed; for example, the preset threshold is 3. This approach ensures that a certain number of manual reclosing operations are allowed to meet commissioning requirements in the event of a fault in the photovoltaic string or its connecting lines, while also preventing maintenance personnel from repeatedly reclosing the switch without troubleshooting the fault, thus avoiding the spread of the fault.

[0071] In this embodiment, the DC switch S1 is equipped with a first drive device controlled by the controller 13 to reset the moving parts, and a second drive device that can reset the moving parts by operating the handle. When the inverter 1 fails, the controller 13 controls the DC switch S1 to open by controlling the first drive device. When the photovoltaic string or its connecting line fails, the controller 13 controls the DC switch S1 to open by controlling the second drive device. This prevents the DC switch S1 from being manually closed when the inverter 1 fails, and allows the DC switch S1 to be manually closed within a preset number of times when the photovoltaic string or its connecting line fails, thereby effectively preventing the spread of the fault.

[0072] See Figure 10 , Figure 10 This is another structural schematic diagram of the inverter provided in this application. For example... Figure 10 As shown, the DC switch S1 includes an operating handle, an operating mechanism, a moving contact, a stationary contact, and a first drive device. The operating mechanism includes a tripping mechanism and a locking mechanism. For a description of the other circuits in the inverter 1 besides the DC switch S1 and their connections, please refer to [link to relevant documentation]. Figure 3 The description of the corresponding part in inverter 1 shown will not be repeated here.

[0073] The main difference from the above embodiments is that, in Figure 10 In the embodiment shown, the inverter has only one first drive device and does not include a second drive device. The functions of the first drive device and the second drive device in the above embodiment are completed by the controller 13 controlling the first drive device.

[0074] In one implementation scenario, during the process of inverter 1 supplying power to the AC grid, if a fault occurs within inverter 1, controller 13 sends a first drive signal to the first drive device. Upon receiving the first drive signal, the first drive device drives its moving component to disengage the latching component from the tripping component, thereby separating the moving contact of DC switch S1 from the stationary contact, i.e., opening DC switch S1. After DC switch S1 is opened, the operating handle, under external force, cannot drive the moving component in the first drive device to reset, thus preventing the tripping component from engaging with the latching component, and consequently preventing the moving contact of DC switch S1 from contacting the stationary contact. Subsequently, when the inverter 1 fault is cleared, controller 13 sends a third drive signal to the first drive device. Upon receiving the third drive signal, the first drive device drives its moving component to reset. After the moving component in the first drive device resets, the operating handle, under external force, drives the tripping component to engage with the latching component, and drives the moving contact of DC switch S1 to contact the stationary contact.

[0075] For ease of understanding, the following example uses the first drive unit as the trip unit TX1, combined with... Figures 11 to 14 The schematic diagram of DC switch S1 shown is used as an example for illustration. Figures 11 to 14 The DC switch S1 shown is Figures 4 to 9 Compared to the DC switch S1 shown, the linkage structure GJ, linkage structure GE, reset component EKF, and trip unit TX2 are no longer included here. Figures 11 to 14 For a description of the structural components of the DC switch S1 shown, please refer to [link / reference needed]. Figures 4 to 9 The description of the corresponding part of the DC switch S1 shown is not repeated here.

[0076] During the process of inverter 1 supplying power to the AC grid, DC switch S1 is in the closed state, corresponding to... Figure 11 The switch status is shown. (For example...) Figure 11 As shown, the latching component M engages with the tripping component DCH, and the moving contact K1 and the stationary contact K2 are in a closed state. The current position of the moving component d1 is x1. If the controller 13 determines that the inverter 1 has malfunctioned based on the electrical parameters of the inverter 1 exceeding the first preset parameter range, the controller 13 sends a first drive signal to the trip unit TX1. Then, as... Figure 12 As shown, when the trip unit TX1 receives the first drive signal, it drives the moving part d1 to move from position x1 to position x2 (i.e., Figure 12 The position of the moving part d1) causes the locking part M to rotate clockwise around point Y, disengaging the locking part M from the tripping part DCH, which then rotates counterclockwise. Driven by the elastic potential energy stored in the elastic element GB, point B moves to the right, causing the moving contact K1 to rotate rapidly clockwise under the pull of the linkage mechanism AB. This separates the moving contact K1 from the stationary contact K2, thus opening the DC switch S1. Because the operating mechanism of the DC switch S1 lacks a reset component for the moving part d1 of the trip unit TX1, even if maintenance personnel manually push the operating handle Lf clockwise after the DC switch S1 opens, they cannot reset the moving part d1. The moving part d1 will remain at position x2, making it impossible to engage the tripping part DCH with the locking part M by operating the operating handle of the DC switch S1, and consequently, impossible to close the DC switch S1 by operating the operating handle of the DC switch S1.

[0077] After the DC switch S1 is tripped, maintenance is required by a professional. Following maintenance, the controller 13 can detect the electrical parameters of the inverter 1. If the electrical parameters of the inverter 1 are within the first preset parameter range, it indicates that the fault in the inverter 1 has been resolved. The controller 13 then sends a third drive signal to the trip unit TX1. Upon receiving the third drive signal, the trip unit TX1 drives the moving part d1 from position x2 to position x1, thereby resetting the moving part d1. The latching part M rotates counterclockwise due to the reset of the moving part d1 and stops at... Figure 13 The position is shown. Since the moving part d1 has been reset, the maintenance personnel can push the operating handle Lf clockwise, which in turn pushes the trip latch component DCH clockwise. The locking part M is then engaged by the trip latch component DCH, meaning the locking part M and the trip latch component DCH are locked together. Figure 14 The position is shown. Afterwards, the maintenance personnel rotate the operating handle Lf counterclockwise, causing the tension of the elastic element GB to extend beyond the left side of the connecting rod structure BC. Point B moves to the left under the tension of the elastic element GB, and the connecting rod structure AB pushes the moving contact K1 downward to close, thus putting the moving contact K1 and the stationary contact K2 in a closed state. Figure 11 As shown in the switch state, DC switch S1 has completed closing.

[0078] Understandably, in the event of a fault in inverter 1, controller 13 controls the DC switch S1 to open by driving the moving parts in the first drive unit. Since DC switch S1 does not have a reset component for the moving parts in the first drive unit, maintenance personnel cannot close DC switch S1 by operating its handle. This prevents DC switch S1 from being manually closed during an inverter 1 fault, thus preventing the fault from spreading. Only after controller 13 detects that the fault in inverter 1 has been cleared, and resets the moving parts in the first drive unit, can maintenance personnel close DC switch S1 by operating its handle. This ensures that when inverter 1 malfunctions, maintenance personnel cannot close DC switch S1 by operating its handle before the fault is cleared. Professional repair is required, and the inverter's internal controller 13 must verify the repair before closing the switch, thus ensuring the safety of maintenance personnel.

[0079] In another implementation scenario, during the process of inverter 1 supplying power to the AC grid, if a fault occurs in the photovoltaic string or its connecting line (an external fault of the inverter), controller 13 sends a first drive signal to the first drive device. Upon receiving the first drive signal, the first drive device drives its moving component to disengage the locking component from the tripping component, thereby separating the moving contact of DC switch S1 from the stationary contact. After the photovoltaic string or its connecting line fails and the moving contact of DC switch S1 separates from the stationary contact, controller 13 immediately sends a third drive signal to the first drive device. Upon receiving the third drive signal, the first drive device resets its moving component. After the moving component in the first drive device resets, the operating handle, under external force, drives the tripping component to engage with the locking component, and drives the moving contact of DC switch S1 to contact the stationary contact.

[0080] In other words, in this implementation scenario, the first drive device immediately sends the third drive signal after sending the first drive signal, without waiting for the photovoltaic string or its connecting lines to malfunction. This allows the moving part of the first drive device to immediately return to position x1 after reaching x2, thus resetting. Maintenance personnel can manually push the operating handle Lf clockwise based on debugging needs. The operating handle Lf then pushes the trip latch component DCH clockwise, causing the locking component M to be latched by the trip latch component DCH. Afterwards, the maintenance personnel push the operating handle Lf counterclockwise, causing the elastic element GB to exert a force beyond the left side of the connecting rod structure BC. Point B moves to the left under the force of the elastic element GB, and the connecting rod structure AB pushes the moving contact K1 downwards to close, thus closing the connection between the moving contact K1 and the stationary contact K2. Figure 11 As shown in the switch state, DC switch S1 has completed closing.

[0081] In other possible implementations, to ensure the safety of maintenance personnel, in the event of a fault in the photovoltaic string or its connecting lines, the controller 13 can continue to monitor the input electrical parameters of the inverter 1 until it detects that the input electrical parameters of the inverter 1 are within the second preset parameter range, indicating that the fault in the photovoltaic string and its connecting lines has been eliminated. Then, the controller 13 sends a third drive signal to the first drive device to reset the moving parts in the first drive device. Since the moving parts in the first drive device are reset, the DC switch S1 can only be manually closed. That is, maintenance personnel cannot directly and manually close the switch; the inverter must detect and confirm that the fault in the photovoltaic string and its lines has been eliminated before the moving parts of the first drive device can be reset, allowing maintenance personnel to then manually close the switch.

[0082] Optionally, after the DC switch S1 trips due to a fault in the photovoltaic string or its connecting lines, the controller 13 sends a third drive signal to the first drive device and begins counting the number of closures between the moving and stationary contacts of the DC switch S1. If the number of times the third drive signal is sent to the first drive device does not exceed a preset threshold before the fault in the photovoltaic string or its connecting lines is cleared and the moving and stationary contacts are separated, the controller sends the third drive signal to the first drive device. If the number of times the second drive signal is sent to the second drive device exceeds a preset threshold when a fault occurs in the photovoltaic string or its connecting lines, the controller stops sending the third drive signal to the first drive device. Since the controller 13 no longer controls the moving parts in the first drive device to reset when the number of closures of the DC switch S1 exceeds the preset threshold when a fault occurs in the photovoltaic string or its connecting lines, it can be ensured that the DC switch S1 cannot be manually closed when the number of closures exceeds the preset threshold. This approach ensures that a certain number of manual reclosing operations are allowed to meet commissioning requirements in the event of a fault in the photovoltaic string or its connecting lines, while also preventing maintenance personnel from repeatedly reclosing the circuit without troubleshooting the fault, which could lead to the spread of the fault.

[0083] In this embodiment, the DC switch S1 is equipped with a first drive device that is controlled solely by the controller 13 to reset the moving parts. When the inverter 1, the photovoltaic string, or their connecting lines fail, the controller 13 controls the first drive device to trip the DC switch S1. After the DC switch S1 trips due to a fault in the photovoltaic string or its connecting lines, the controller ensures that the number of times the moving parts in the first drive device are reset does not exceed a preset threshold. This prevents the DC switch S1 from being manually closed when the inverter 1 fails, while allowing it to be manually closed within a preset number of times when the photovoltaic string or its connecting lines fail, effectively preventing the fault from spreading. Furthermore, the limited number of drive devices in the DC switch S1 effectively reduces the size and circuit cost of the DC switch S1, thereby reducing the size and circuit cost of the inverter 1.

[0084] 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. An inverter, characterized in that, The inverter includes an input terminal, a DC switch, multiple DC / DC converters, a DC bus, a DC / AC converter, a controller, and an output terminal. The input terminal is used to connect to a photovoltaic string, and the output terminal is used to connect to the AC grid. The DC switch includes an operating handle, an operating mechanism, a moving contact, a stationary contact, a first drive device, and a second drive device, wherein: The input terminals of the plurality of DC / DC converters are connected to the input terminal of the inverter through the DC switch, and the output terminals of the plurality of DC / DC converters are connected in parallel to the DC bus; The input terminal of the DC / AC converter is connected to the DC bus, and the output terminal of the DC / AC converter is connected to the output terminal of the inverter. The operating mechanism includes a locking component, a tripping component, a transmission assembly, and a reset component; the operating handle, the tripping component, the reset component, and the moving contact are respectively connected to the transmission assembly. The operating mechanism is used to drive the moving contact and the stationary contact to make contact and separate. When the jump-lock component is engaged with the locking component, the operating handle can drive the transmission assembly to drive the moving contact and the stationary contact to make contact and separate. When the jump-lock component is disengaged from the locking component, the operating handle cannot drive the transmission assembly to drive the moving contact and the stationary contact to make contact and separate. The controller is configured to send a first drive signal to the first drive device in the event of a fault in the inverter. The first driving device is used to drive the moving part in the first driving device to move when receiving the first driving signal, so as to drive the locking part to disengage from the jumping part, and cause the transmission assembly to drive the moving contact to separate from the stationary contact; The controller is also configured to send a second drive signal to the second drive device in the event of a fault in the photovoltaic string or its connection line; The second driving device is used to drive the moving part in the second driving device to move when receiving the second driving signal, so as to drive the locking part to disengage from the jumping part, and cause the transmission assembly to drive the moving contact to separate from the stationary contact; After the second driving device drives the moving contact to separate from the stationary contact, the operating handle is also used to drive the transmission assembly to move the reset component when subjected to external force, so as to drive the moving component in the second driving device to reset. After the moving part in the second driving device is reset, the operating handle is also used to drive the jump buckle component to engage with the locking component when subjected to external force, so that the operating handle can drive the transmission component to drive the moving contact to contact the stationary contact.

2. The inverter according to claim 1, characterized in that, The controller is specifically used to: in the event of a fault in the photovoltaic string or its connection line, if the number of times the second drive signal is sent to the second drive device does not exceed a preset threshold, then send a second drive signal to the second drive device. The controller is further configured to: send the first drive signal to the first drive device when the number of times the second drive signal is sent to the second drive device exceeds a preset threshold, or when the photovoltaic string or its connection line fails.

3. The inverter according to claim 1 or 2, characterized in that, The controller is also used to send a third drive signal to the first drive unit when the inverter fault is cleared. The first driving device is further configured to drive the moving parts in the first driving device to reset when a third driving signal is received; After the moving part in the first driving device is reset, the operating handle is also used to drive the jump buckle component to engage with the locking component when subjected to external force, so that the operating handle can drive the transmission component to drive the moving contact to contact the stationary contact.

4. The inverter according to claim 1 or 2, characterized in that, The controller is also used to determine that the inverter has malfunctioned when the electrical parameters of the inverter exceed the range of a first preset parameter, wherein the electrical parameters of the inverter include the bus voltage value or the bus current value of the DC bus.

5. The inverter according to claim 1 or 2, characterized in that, The controller is also used to determine that the photovoltaic string or its connection line has failed when the electrical parameters of the photovoltaic string exceed the range of the second preset parameters, wherein the electrical parameters of the photovoltaic string include the output voltage value, the output current value, or the insulation resistance to ground value.

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