A direct current arc detection circuit, a detection method and an inverter

Abstract

The application discloses a direct-current arc detection circuit, a detection method and an inverter. The direct-current arc detection circuit comprises a controller, a driving module, an arc detection module and a signal processing module. The controller is used for generating a self-checking control signal, collecting a first self-checking feedback signal and a second self-checking feedback signal, and performing self-checking of the arc detection module and the signal processing module based on the first self-checking feedback signal and the second self-checking feedback signal. The input end of the driving module is electrically connected with the controller to receive the self-checking control signal. The driving module is switched between turn-on and turn-off based on the self-checking control signal. The output end of the arc detection module is connected with the output end of the driving module. The connection point is electrically connected with the controller to output the first self-checking feedback signal to the controller. The connection point is also electrically connected with the controller through the signal processing module to output the second self-checking feedback signal to the controller. The application can realize independent diagnosis of the arc detection module and the signal processing module.

Description

Technical Field

[0001] This invention relates to the field of inverter technology, and in particular to a DC arc detection circuit, detection method, and inverter. Background Technology

[0002] In DC systems such as photovoltaic and energy storage systems, DC arcing faults can cause high temperatures and fires, posing a significant threat to the safe operation of the system. Therefore, the industry commonly uses instrument transformers to detect arcing phenomena in the lines in real time. To ensure the reliability of the instrument transformers' arcing detection, a system self-test must be performed before the DC system is connected to the grid.

[0003] In related technologies, a self-test coil inside the current transformer is typically used. A dedicated noise generation circuit generates an excitation signal that simulates the characteristics of an electric arc. This excitation signal drives the self-test coil via a filter circuit, generating an alternating magnetic field in the magnetic core and coupling it to the detection coil. The alternating current induced in the detection coil is converted into a sampling voltage by a sampling resistor, and then sent to a microcontroller for self-testing after passing through a second filter circuit. However, this self-testing method has multiple functional components in its excitation and detection path, and any malfunction in any of these components will cause the self-test to fail. When the self-test fails, the system cannot effectively identify the specific location of the fault, thus increasing the difficulty and time required for troubleshooting. Summary of the Invention

[0004] One object of the present invention is to provide a DC arc detection circuit that can solve or alleviate at least one of the defects in the above-mentioned background art.

[0005] Another object of the present invention is to provide a detection method applied to the above-described DC arc detection circuit to solve or alleviate at least one of the defects in the above-described background art.

[0006] Another object of the present invention is to provide an inverter having the above-described DC arc detection circuit to solve or alleviate at least one of the defects in the above-described background art.

[0007] This application provides a DC arc detection circuit, comprising: a controller, a drive module, an arc detection module, and a signal processing module; wherein the controller is used to generate a self-test control signal, and to acquire a first self-test feedback signal and a second self-test feedback signal, and to perform self-tests on the arc detection module and the signal processing module based on the first self-test feedback signal and the second self-test feedback signal; the input terminal of the drive module is electrically connected to the controller to receive the self-test control signal, and the drive module switches between on and off based on the self-test control signal; the output terminal of the arc detection module is connected to the output terminal of the drive module, and a connection point is electrically connected to the controller to output the first self-test feedback signal to the controller; the connection point is also electrically connected to the controller through the signal processing module to output the second self-test feedback signal to the controller.

[0008] As a preferred embodiment, the arc detection module includes a current transformer and a sampling resistor. The current transformer has a magnetic ring and a detection coil wound around the magnetic ring. The DC cable to be detected passes through the magnetic ring. The detection coil and the sampling resistor are connected in parallel between a reference voltage source and the output terminal of the drive module. The detection coil cooperates with the DC cable to convert the primary magnetic field generated by the DC cable into an alternating current. The sampling resistor is used to convert the alternating current into a voltage signal.

[0009] As a preferred embodiment, the drive module includes a first resistor, a second resistor, a third resistor, and a control switch. One end of the first resistor is electrically connected to the controller for receiving the self-test control signal, and the other end of the first resistor is connected to the control terminal of the control switch. The control switch switches between on and off based on the self-test control signal. One end of the second resistor is connected to the output terminal of the control switch, and the other end of the second resistor is connected to the output terminal of the arc detection module. The reference terminal of the control switch is grounded. One end of the third resistor is connected between the first resistor and the control terminal of the control switch, and the other end of the third resistor is grounded.

[0010] Preferably, the self-test control signal includes a first self-test control signal. The drive module receives the first self-test control signal and outputs the first self-test feedback signal to the controller via the connection point between the output terminal of the arc detection module and the output terminal of the drive module. The first self-test control signal is an AC signal, and the first self-test feedback signal is a periodic signal. The controller performs feature analysis on the first self-test feedback signal and / or calculates the actual magnetic inductance L of the current transformer. act This is to determine whether the arc detection module is functioning properly.

[0011] Preferably, the controller performs feature analysis on the first self-test feedback signal to determine whether the arc detection module is functioning correctly, including at least one of the following: when the controller detects that the peak voltage of the first self-test feedback signal is within a preset peak range, it determines that the arc detection module is normally connected, wherein the preset peak range is determined based on the normal peak voltage, and the normal peak voltage V... peak =V ref +I L0 *R s When the controller detects that the trough voltage of the first self-test feedback signal is within a preset trough range, it determines that the arc detection module is normally connected; wherein, the preset trough range is determined based on the normal trough voltage, and the normal trough voltage V valley =V ref -[(R s *R2) / (R s +R2)]*I L0 *e -(Rs / L)*T When the controller detects that the voltage amplitude of the first self-test feedback signal is within a preset amplitude range, it determines that the arc detection module is normally connected; wherein, the preset amplitude range is determined based on the difference between the normal peak voltage and the normal trough voltage; when the controller detects that the high level of the first self-test feedback signal is within a first preset voltage range, it determines that the arc detection module is disconnected, wherein, the first preset voltage range is determined based on an abnormal high level, and the abnormal high level V g =V ref When the controller detects a low level in the first self-test feedback signal within a second preset voltage range, it determines that the arc detection module is disconnected. The second preset voltage range is determined based on an abnormal low level, where the abnormal low level V... d =V ref *[R2 / (R s +R2)];wherein, V ref R is the reference voltage value. s R1 is the resistance value of the sampling resistor, R2 is the resistance value of the second resistor, and I L0 For steady-state inductor current, I L0 =V ref / R2, L is the theoretical magnetic inductance of the current transformer, and T is the duration of the control switch being turned off.

[0012] As a preferred embodiment, the self-test control signal includes a first self-test control signal. The drive module receives the first self-test control signal and outputs the first self-test feedback signal to the controller via the connection point between the output terminal of the arc detection module and the output terminal of the drive module. The first self-test control signal is a high-level signal, and the first self-test feedback signal is a DC signal. The controller determines whether the arc detection module is functioning correctly based on the voltage value of the first self-test feedback signal.

[0013] As a preferred embodiment, the controller determines whether the arc detection module is functioning correctly based on the voltage value of the first self-test feedback signal, including at least one of the following: when the controller detects that the voltage value of the first self-test feedback signal is within a third preset voltage range, it determines that the arc detection module is normally connected; wherein, the third preset voltage range is determined based on a normal voltage, and the normal voltage V... z =V ref *{R2 / [R2+((R CT *R s ) / (R CT +R s When the controller detects that the voltage value of the first self-test feedback signal is within a fourth preset voltage range, it determines that the arc detection module is disconnected; wherein, the fourth preset voltage range is determined based on an abnormal voltage, and the abnormal voltage V y =V ref *[R2 / (R s +R2)];wherein, V ref R is the reference voltage value. CT R is the resistance value of the detection coil. s R1 is the resistance value of the sampling resistor, and R2 is the resistance value of the second resistor.

[0014] As a preferred embodiment, the self-test control signal includes a second self-test control signal. The drive module receives the second self-test control signal and outputs the second self-test feedback signal to the controller via the signal processing module. The second self-test control signal is an AC signal, and the second self-test feedback signal is a periodic signal. The controller performs feature analysis on the second self-test feedback signal to determine whether the signal processing module is functioning correctly.

[0015] A second aspect of this application provides a DC arc detection method applied to the DC arc detection circuit described above, comprising: a controller of the DC arc detection circuit generating a first self-test control signal; the controller acquiring a first self-test feedback signal and determining whether the arc detection module of the DC arc detection circuit is normal based on the first self-test feedback signal; if the controller determines that the arc detection module is abnormal, then performing abnormal feedback; if the controller determines that the arc detection module is normal, then generating a second self-test control signal; the controller acquiring the second self-test feedback signal and determining whether the signal processing module of the DC arc detection circuit is normal based on the second self-test feedback signal; if the controller determines that the signal processing module is abnormal, then performing abnormal feedback; if the controller determines that the signal processing module is normal, then determining that the DC arc detection circuit has passed the self-test.

[0016] A third aspect of this application provides an inverter including the DC arc detection circuit described above.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The controller of the DC arc detection circuit is configured to acquire a first self-test feedback signal that is not processed by the signal processing module and a second self-test feedback signal that is processed by the signal processing module. Then, through the first self-test feedback signal and the second self-test feedback signal, the arc detection module and the signal processing module can be independently diagnosed, which can quickly and accurately identify the fault location, thereby reducing the maintenance difficulty and time consumption of the DC arc detection circuit. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a DC arc detection circuit according to some embodiments of this application.

[0019] Figure 2 This is a schematic diagram of a drive module disposed in a DC arc detection circuit according to some embodiments of this application.

[0020] Figure 3 This is a schematic diagram of a current transformer according to some embodiments of this application.

[0021] Figure 4 This is a flowchart of a DC arc detection method according to some embodiments of this application. Detailed Implementation

[0022] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0023] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects and do not necessarily describe a specific order or sequence.

[0024] The terms "comprising" and "having" in the description and claims of this application, as well as any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0025] A DC arc detection circuit, as Figure 1 and Figure 2 shown, includes: a controller, a drive module, an arc detection module, and a signal processing module; wherein, the controller is used to generate a self-check control signal, and collect a first self-check feedback signal and a second self-check feedback signal, and perform self-check on the arc detection module and the signal processing module based on the first self-check feedback signal and the second self-check feedback signal; the input end of the drive module is electrically connected to the controller to receive the self-check control signal, and the drive module switches between on and off based on the self-check control signal; the output end of the arc detection module is connected to the output end of the drive module, and the connection point is electrically connected to the controller to output the first self-check feedback signal to the controller; the connection point is also electrically connected to the controller through the signal processing module to output the second self-check feedback signal to the controller.

[0026] It should be understood that the controller of the DC arc detection circuit is configured to respectively obtain the first self-check feedback signal that has not been processed by the signal processing module, and the second self-check feedback signal that has been processed by the signal processing module. Furthermore, through the first self-check feedback signal and the second self-check feedback signal, independent diagnosis of the arc detection module and the signal processing module can be achieved, and the fault location can be quickly and accurately identified, thereby reducing the maintenance difficulty and time consumption of the DC arc detection circuit.

[0027] Furthermore, in this embodiment, the controller directly inputs a self-check signal to the arc detection module via the drive module, which can eliminate the additional noise generation circuit and the filtering circuit supporting the noise generation circuit, simplify the topological structure of the DC arc detection circuit, reduce the number of components, thereby reducing the overall cost of the DC arc detection circuit and improving the reliability of the DC arc detection circuit.

[0028] In some embodiments, as Figures 1-3 shown, the arc detection module includes a current transformer and a sampling resistor. The current transformer has a magnetic core and a detection coil wound around the magnetic core. The DC cable to be detected passes through the magnetic core, and the current I in the DC cable pThis is the primary current, which can excite a primary magnetic field in the magnetic ring. The detection coil and sampling resistor are connected in parallel between the reference voltage source and the output terminal of the drive module. In other words, one end of the parallel connection between the detection coil and the sampling resistor is connected to the reference voltage source, and the other end serves as the output terminal of the arc detection module, thus connecting to the output terminal of the drive module. The detection coil works with a DC cable to convert the primary magnetic field generated by the DC cable into an alternating current. The sampling resistor is used to convert the alternating current into a voltage signal.

[0029] It is understandable that the current transformer only has a detection coil, which eliminates the need for an additional second coil dedicated to self-testing in related technologies. In other words, it can reduce the number of coils, simplify the structure of the current transformer, thereby reducing the size of the current transformer, lowering the production and maintenance costs of the current transformer, and facilitating commissioning.

[0030] It is worth mentioning that in this embodiment, the detection coil can be used for both DC arc detection and self-testing of the arc detection module. Specifically, the detection coil of the current transformer enables self-testing of the arc detection module; the DC cable of the current transformer and the detection coil work together to achieve DC arc detection, thereby improving the utilization rate of the detection coil and the integration of the DC arc detection circuit. Furthermore, connecting the detection coil and the sampling resistor in parallel with a reference voltage source provides a stable DC bias for the voltage signal output by the arc detection module, thereby improving the signal quality of the first self-test feedback signal and the second feedback signal, and enhancing the accuracy of the controller's judgment.

[0031] In some embodiments, such as Figure 2 As shown, the drive module includes a first resistor, a second resistor, a third resistor, and a control switch. Specifically, one end of the first resistor is electrically connected to the controller to receive a self-test control signal, and the other end of the first resistor is connected to the control terminal of the control switch. The control switch switches between on and off based on the self-test control signal. One end of the second resistor is connected to the output terminal of the control switch, and the other end of the second resistor is connected to the output terminal of the arc detection module. In other words, the other end of the second resistor serves as the output terminal of the drive module, allowing it to be connected to the output terminal of the arc detection module. The reference terminal of the control switch is grounded. One end of the third resistor is connected between the first resistor and the control terminal of the control switch, and the other end of the third resistor is grounded.

[0032] It should be understood that the drive module receives the self-test control signal generated by the controller and drives the control switch to switch between on and off based on the self-test control signal, thereby stimulating the arc detection module to achieve self-testing of the arc detection module. Furthermore, the simplified topology of the drive module in this embodiment helps reduce the production and maintenance costs of the drive module and facilitates debugging.

[0033] Specifically, the drive module receives the self-test control signal through the first resistor and reliably clamps the control terminal level of the control switch through a voltage divider and discharge path formed by the third resistor, helping to ensure that the control switch is stably turned off when there is a low-level signal or an invalid drive signal. Furthermore, when the control switch is on, the drive module provides a circuit to the detection coil and sampling resistor connected in parallel in the arc detection module via the second resistor, thereby establishing a corresponding inductor current in the detection coil. Even further, when the control switch is off, the inductor current in the detection coil is released through a freewheeling circuit formed by the sampling resistor. In other words, through the drive module and the arc detection module, a first self-test feedback signal that can be collected and analyzed by the controller can be generated based on the self-test control signal, thereby realizing the self-test of the arc detection module.

[0034] In at least one embodiment, such as Figure 2 As shown, the control switch is implemented as an NPN transistor, wherein the base of the NPN transistor is electrically connected to the controller via a first resistor; the collector is connected to one end of a second resistor; and the emitter is grounded. It is worth noting that those skilled in the art can adjust the specific type of the control switch according to actual operating conditions and requirements, for example, implementing the control switch as a MOS transistor, relay, etc., and such adjustments all fall within the protection scope of this application.

[0035] In some embodiments, such as Figure 1 and Figure 2 As shown, the self-test control signal includes a first self-test control signal. The drive module receives the first self-test control signal and outputs a first self-test feedback signal to the controller via the connection point between the output terminal of the arc detection module and the output terminal of the drive module. The first self-test control signal is an AC signal, and the first self-test feedback signal is a periodic signal. The controller performs feature analysis on the first self-test feedback signal and / or calculates the actual magnetic inductance L of the current transformer. act This is to determine whether the arc detection module is functioning properly.

[0036] It should be understood that the first self-test control signal generated by the controller is an AC signal, and the first self-test feedback signal generated based on the first self-test control signal is a periodic signal. Furthermore, the controller performs feature analysis on the first self-test feedback signal, including but not limited to analyzing the peak voltage, trough voltage, and voltage amplitude of the first self-test feedback signal, thereby determining whether the arc detection module is properly connected, for example, identifying whether the detection coil is partially burned out and open-circuited. Even further, the controller is configured to calculate the actual magnetic inductance L of the current transformer based on the first self-test feedback signal. act This allows for the quantitative detection of the current transformer's performance status, helping to identify performance degradation caused by device aging or physical damage as early as possible. This improves the predictability of DC arc detection circuit maintenance and the reliability of DC arc detection circuit operation.

[0037] It is worth mentioning that when the first self-test control signal is an AC signal, it can be implemented as a square wave signal, a triangular wave signal, a sawtooth wave signal, a sine wave signal, etc., and this application does not impose any specific restrictions on it.

[0038] In some embodiments, the controller performs feature analysis on the first self-test feedback signal to determine whether the arc detection module is functioning properly, including at least one of the following: when the controller detects that the peak voltage of the first self-test feedback signal is within a preset peak range, it determines that the arc detection module is normally connected, wherein the preset peak range is determined based on the normal peak voltage V. peak =V ref +I L0 *R s When the controller detects that the trough voltage of the first self-test feedback signal is within the preset trough range, it determines that the arc detection module is normally connected; wherein, the preset trough range is determined based on the normal trough voltage, and the normal trough voltage V valley =V ref -[(R s *R2) / (R s +R2)]*I L0 *e -(Rs / L)*T When the controller detects that the voltage amplitude of the first self-test feedback signal is within a preset amplitude range, it determines that the arc detection module is normally connected; wherein, the preset amplitude range is determined based on the difference between the normal peak voltage and the normal trough voltage; when the controller detects that the high level of the first self-test feedback signal is within the first preset voltage range, it determines that the arc detection module is disconnected; wherein, the first preset voltage range is determined based on an abnormal high level, where the abnormal high level V... g =V ref When the controller detects a low level in the first self-test feedback signal within the second preset voltage range, it determines that the arc detection module is disconnected. The second preset voltage range is determined based on an abnormal low level, where the abnormal low level V... d =V ref *[R2 / (R s +R2)]. Wherein, V ref R is the reference voltage value. s R1 is the resistance value of the sampling resistor, R2 is the resistance value of the second resistor, and I... L0 For steady-state inductor current, I L0 =V ref / R2, L is the theoretical magnetic inductance of the transformer, T is the duration of the control switch being turned off, and the on-state voltage of the control switch is ignored.

[0039] It is understandable that when a DC system such as a photovoltaic or energy storage system is powered on, no current flows through the DC cable. With the arc detection module properly connected, when the control switch is turned on for the first time under the first self-test control signal, the grounding loop formed is: reference voltage source → parallel detection coil and sampling resistor → second resistor → control switch → ground. Since the control switch is turned on for the first time, the initial current of the detection coil is 0, and it cannot instantaneously establish current. Therefore, almost all the current flows sequentially through the sampling resistor, the second resistor, and the control switch. At this time, the voltage value of the first self-test feedback signal is V. ref *[R2 / (R s +R2). Subsequently, the self-induced electromotive force of the detection coil decreases, the current of the detection coil gradually increases, and the voltage value of the first self-test feedback signal also gradually increases. When the current of the detection coil becomes constant, the detection coil is considered to be short-circuited. At this time, the voltage value of the first self-test feedback signal is V. ref Steady-state inductor current I L0 =V ref / R2.

[0040] The moment the control switch is turned off under the first self-test control signal, the grounding circuit mentioned above is cut off. Since the current in the detection coil cannot change abruptly, it maintains its original direction. Figure 2 The circuit moves from top to bottom, generating a reverse induced electromotive force (EMF) with the top of the coil being negative and the bottom being positive. This EMF forms a freewheeling circuit via the sampling resistor. At this time, the voltage value of the first self-test feedback signal changes from the reference voltage value V. ref This is formed by superimposing the induced voltage. Subsequently, the voltage value of the first self-test feedback signal first rises to a peak, and then slowly falls back as the current in the self-test coil decays. Specifically, under the condition that the arc detection module is normally connected, the normal peak voltage V of the first self-test feedback signal is... peak =V ref +I L0 *R s .

[0041] The moment the control switch is turned on again under the first self-test control signal, the grounding loop described above is re-established. Since the residual current in the detection coil cannot change abruptly, it maintains its original direction. Figure 2 From top to bottom, and assuming the detection coil is equivalent to an independent power supply, the current in the detection coil generates a voltage drop through the parallel circuit formed by the sampling resistor and the second resistor. At this time, the voltage value of the first self-test feedback signal changes from the reference voltage value V. ref This is added together with the aforementioned voltage drop; in other words, it is the voltage drop at the reference voltage value V. refA voltage drop occurs based on this. Subsequently, the voltage value of the first self-test feedback signal first drops to a trough, and then slowly rises as the current in the self-test coil increases. Specifically, when the arc detection module is properly connected, the normal trough voltage V of the first self-test feedback signal... valley =V ref -[(R s *R2) / (R s +R2)]*I L0 *e -(Rs / L)*T .

[0042] Therefore, in this embodiment, it is possible to base the normal peak voltage V peak Determine the preset peak range, based on the normal valley voltage V valley Determine the preset trough range, and the normal peak voltage V peak With normal trough voltage V valley The difference determines the preset amplitude range. Then, the controller determines whether the arc detection module is properly connected by comparing at least one of the following three: the peak voltage of the first self-test feedback signal with the preset peak range, the trough voltage of the first self-test feedback signal with the preset trough range, and the voltage amplitude of the first self-test feedback signal with the preset amplitude range.

[0043] In one specific embodiment, when the controller detects that the peak voltage of the first self-test feedback signal is within a preset peak range and the trough voltage of the first self-test feedback signal is within a preset trough range, it determines that the arc detection module is normally connected; otherwise, it determines that the arc detection module is disconnected. It should be understood that this setting helps improve the reliability of the self-test.

[0044] In one specific embodiment, when the controller measures the actual trough voltage V of the first self-test feedback signal... valley-act Afterwards, it is possible to base it on equation V valley-act =V ref -[(R s *R2) / (R s +R2)]*I L0 *e -(Rs / Lact)*T Calculate the actual magnetic inductance L of the current transformer. act Furthermore, the controller compares the actual magnetic flux density L... act Compared with the preset magnetic field range, when the actual magnetic field quantity L act Within a preset magnetic flux range, the current transformer's magnetic flux is determined to be normal; otherwise, it is determined to be abnormal. The preset magnetic flux range is determined based on the theoretical magnetic flux L of the current transformer. This setup allows for quantitative detection of the current transformer's performance status, enabling early identification of performance degradation caused by device aging or physical damage, and improving the predictability of DC arc detection circuit maintenance.

[0045] When the arc detection module is disconnected, specifically when the detection coil is disconnected, and the control switch is turned on under the drive of the first self-test control signal, the grounding loop formed is: reference voltage source → sampling resistor → second resistor → control switch → ground; at this time, the voltage value of the first self-test feedback signal is abnormally low V. d =V ref *[R2 / (R s +R2). Furthermore, when the control switch is turned off under the drive of the first self-test control signal, the grounding circuit mentioned above is cut off; at this time, the voltage value of the first self-test feedback signal is abnormally high level V. g =V ref In other words, when the detection coil is disconnected, the first self-test control signal is a periodic pulse signal.

[0046] Therefore, this embodiment can be based on the abnormal high level V g Determine the first preset voltage range, based on the abnormal low level V d The controller determines whether the arc detection module is disconnected by comparing at least one of the following: the high level of the first self-test feedback signal with the first preset voltage range, and the low level of the first self-test feedback signal with the second preset voltage range.

[0047] In one specific embodiment, when the controller detects that the high level of the first self-test feedback signal is within a first preset voltage range and the low level of the first self-test feedback signal is within a second preset voltage range, it determines that the arc detection module is disconnected; otherwise, it determines that the arc detection module is normally connected. It should be understood that this setting helps improve the reliability of the self-test.

[0048] In other embodiments, the first self-test control signal is a high-level signal, and the first self-test feedback signal is a DC signal. The controller determines whether the arc detection module is functioning correctly based on the voltage value of the first self-test feedback signal. In other words, the controller generates a high-level first self-test control signal, and the resulting first self-test feedback signal is a DC signal. Furthermore, the controller analyzes the voltage value of the first self-test feedback signal to determine whether the arc detection module is functioning correctly. It should be understood that this configuration simplifies the self-test logic, thereby improving the self-test response speed and enabling the controller to complete the connection determination of the arc detection module in a shorter time. It also reduces the controller's computational load, thus saving storage space and processing time.

[0049] In some embodiments, the controller determines whether the arc detection module is functioning correctly based on the voltage value of the first self-test feedback signal, including at least one of the following: when the controller detects that the voltage value of the first self-test feedback signal is within a third preset voltage range, it determines that the arc detection module is normally connected; wherein, the third preset voltage range is determined based on a normal voltage, and the normal voltage V... z =V ref *{R2 / [R2+((R CT *R s ) / (R CT +R s When the controller detects that the voltage value of the first self-test feedback signal is within the fourth preset voltage range, it determines that the arc detection module is disconnected; wherein, the fourth preset voltage range is determined based on abnormal voltage, and the abnormal voltage V y =V ref *[R2 / (R s +R2)];wherein, V ref R is the reference voltage value. CT To detect the resistance value of the coil, R s R1 is the resistance value of the sampling resistor, R2 is the resistance value of the second resistor, and the on-state voltage of the control switch is ignored.

[0050] It is understandable that when a DC system such as a photovoltaic or energy storage system is powered on, no current flows through the DC cable. With the arc detection module properly connected, when the control switch is turned on by the first self-test control signal, the grounding loop formed is: reference voltage source → parallel detection coil and sampling resistor → second resistor → control switch → ground. At this time, through the voltage division of the parallel detection coil and sampling resistor, and the second resistor, the voltage value of the first self-test feedback signal is the normal voltage V. z =V ref *{R2 / [R2+((R CT *R s ) / (R CT +R s Furthermore, when the arc detection module is disconnected, and the control switch is turned on under the drive of the first self-test control signal, the grounding loop formed is: reference voltage source → sampling resistor → second resistor → control switch → ground. At this time, through the voltage division of the sampling resistor and the second resistor, the voltage value of the first self-test feedback signal is the abnormal voltage V. y =V ref *[R2 / (R s +R2)].

[0051] Therefore, in this embodiment, it is possible to base the normal voltage V z Determine the third preset voltage range, based on the abnormal voltage V yA fourth preset voltage range is determined, and then the controller compares at least one of the voltage values ​​of the first self-test feedback signal and the third preset voltage range, and the voltage values ​​of the first self-test feedback signal and the fourth preset voltage range, to determine whether the arc detection module is properly connected or disconnected. Preferably, the resistance value R of the detection coil is... CT The resistance value R of the sampling resistor s The ratio is extremely small, thus making the normal voltage V z With abnormal voltage V y The difference is even more pronounced.

[0052] In one specific embodiment, when the controller detects that the voltage value of the first self-test feedback signal is within a third preset voltage range, it determines that the arc detection module is normally connected; otherwise, it determines that the arc detection module is disconnected. In another specific embodiment, when the controller detects that the voltage value of the first self-test feedback signal is within a fourth preset voltage range, it determines that the arc detection module is disconnected; otherwise, it determines that the arc detection module is normally connected. It should be understood that this configuration simplifies the self-test logic and improves the response speed of the self-test.

[0053] In some embodiments, such as Figure 1 and Figure 2 As shown, the self-test control signal includes a second self-test control signal. The drive module receives the second self-test control signal and outputs a second self-test feedback signal to the controller via the signal processing module. The second self-test control signal is an AC signal, and the second self-test feedback signal is a periodic signal. The controller performs feature analysis on the second self-test feedback signal to determine whether the signal processing module is functioning properly.

[0054] It is understandable that when a DC system such as a photovoltaic or energy storage system is powered on, no current flows through the DC cable. Furthermore, assuming both the arc detection module and the signal processing module are functioning normally, when the second self-test control signal is an AC signal, the second self-test feedback signal generated based on this control signal is a periodic signal. Specifically, the second self-test feedback signal is generated at a reference voltage value V. ref Based on the superposition of periodic peak and trough signals, the waveform generation mechanism of the second self-test feedback signal is the same as that of the first self-test feedback signal when the arc detection module is normally connected and the first self-test control signal is an AC signal, as described above. Therefore, it will not be described again here.

[0055] It is worth mentioning that the second self-test feedback signal, after being processed by the signal processing module, is input to the controller for feature extraction. Due to the inherent transmission characteristics of the signal processing module, the processed second self-test feedback signal will introduce a definite DC offset and / or gain amplification effect. In a specific embodiment, when the DC offset and AC amplitude extracted by the controller based on the second self-test feedback signal are both within a preset allowable range, it indicates that the transmission characteristics of the signal processing module meet the design tolerance, and the controller determines that the signal processing module is working normally; conversely, if at least one of the DC offset or AC amplitude exceeds the corresponding preset allowable range, the signal processing module is determined to be faulty.

[0056] Furthermore, the first self-test control signal and the second self-test control signal can use the same signal form and parameters, or they can use different signal forms or parameters; this application does not impose specific limitations on this. In one specific embodiment, the first self-test control signal and the second self-test control signal have the same signal form and parameters, so the controller can generate the self-test control signal only once and simultaneously or stepwise acquire the first self-test feedback signal and the second self-test feedback signal. In another specific embodiment, the controller generates the first self-test control signal and the second self-test control signal stepwise, and correspondingly acquires the first self-test feedback signal and the second self-test feedback signal stepwise, thereby enabling the controller to first determine whether the arc detection module is normal, and then, based on the normality of the arc detection module, further determine whether the signal processing module is normal, making the self-test process clearer and simpler.

[0057] The signal processing module can be implemented as an active filter amplifier circuit, or as other circuit structures capable of filtering and amplification, such as an adjustment circuit composed of a passive filter network and an independent operational amplifier, or a digital filter and gain adjustment circuit based on the internal resources of the controller. The topologies of the above circuits are conventional choices for those skilled in the art, and therefore will not be described in detail here. When the second self-test control signal is an AC signal, it can be implemented as a square wave signal, a triangular wave signal, a sawtooth wave signal, a sine wave signal, etc., and this application does not impose specific limitations on this.

[0058] A DC arc detection method, such as Figure 4As shown, the DC arc detection circuit described above includes: a controller of the DC arc detection circuit generating a first self-test control signal; the controller acquiring a first self-test feedback signal and determining whether the arc detection module of the DC arc detection circuit is normal based on the first self-test feedback signal; if the controller determines that the arc detection module is abnormal, it performs abnormal feedback; if the controller determines that the arc detection module is normal, it generates a second self-test control signal; the controller acquiring the second self-test feedback signal and determining whether the signal processing module of the DC arc detection circuit is normal based on the second self-test feedback signal; if the controller determines that the signal processing module is abnormal, it performs abnormal feedback; if the controller determines that the signal processing module is normal, it determines that the DC arc detection circuit has passed the self-test.

[0059] It should be understood that the DC arc detection method in this embodiment allows for step-by-step self-testing of the arc detection module and the signal processing module, making the self-testing process clear, concise, and efficient. This helps to avoid misjudging the arc detection module in the event of an abnormality in the subsequent signal processing module.

[0060] It is worth mentioning that the specific implementation of abnormal feedback includes, but is not limited to: outputting a shutdown command to stop the operation of the DC system; driving the audible and / or visual alarm devices to issue warning signals; displaying the corresponding fault code or fault information on the display interface; and writing the abnormal event and the time of occurrence into the fault log.

[0061] In some embodiments, such as Figure 4 As shown, the DC arc detection method also includes starting the grid-connected power supply after determining that the DC arc detection circuit has passed its self-test. At this time, a current I flows through the DC cable. p By using a detection coil in conjunction with a DC cable, the primary magnetic field generated by the DC cable can be converted into an alternating current. Furthermore, the alternating current can be converted into a voltage signal through a sampling resistor, and after being processed by a signal processing module, an arcing signal is generated and input to the controller. The controller can determine whether an arcing phenomenon has occurred by detecting the arcing signal, and thus provide abnormal feedback when an arcing phenomenon occurs, which helps to ensure the safe and reliable operation of the DC system.

[0062] An inverter includes the aforementioned DC arc detection circuit. It should be understood that the DC arc detection circuit enables independent diagnosis of the arc detection module and the signal processing module, allowing for rapid and accurate identification of fault locations, thereby improving the inverter's reliability and helping to ensure the long-term stability of the inverter's operation.

[0063] The basic principles, main features, and advantages of this invention have been described above. Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection claimed by this invention is defined by the appended claims and their equivalents.

Claims

1. A DC arc detection circuit, characterized in that, include: The system comprises a controller, a drive module, an arc detection module, and a signal processing module; among which, The controller is used to generate a self-test control signal, and to acquire a first self-test feedback signal and a second self-test feedback signal, and to perform self-tests on the arc detection module and the signal processing module based on the first self-test feedback signal and the second self-test feedback signal; The input terminal of the drive module is electrically connected to the controller to receive the self-test control signal, and the drive module switches between on and off based on the self-test control signal; The output terminal of the arc detection module is connected to the output terminal of the drive module, and the connection point is electrically connected to the controller to output the first self-test feedback signal to the controller; the connection point is also electrically connected to the controller through the signal processing module to output the second self-test feedback signal to the controller.

2. The DC arc detection circuit according to claim 1, characterized in that, The arc detection module includes a current transformer and a sampling resistor. The current transformer has a magnetic ring and a detection coil wound around the magnetic ring. The DC cable to be detected passes through the magnetic ring. The detection coil and the sampling resistor are connected in parallel between a reference voltage source and the output terminal of the drive module. The detection coil cooperates with the DC cable to convert the primary magnetic field generated by the DC cable into an alternating current. The sampling resistor is used to convert the alternating current into a voltage signal.

3. The DC arc detection circuit according to claim 2, characterized in that, The drive module includes a first resistor, a second resistor, a third resistor, and a control switch. One end of the first resistor is electrically connected to the controller to receive the self-test control signal. The other end of the first resistor is connected to the control terminal of the control switch. The control switch switches between on and off based on the self-test control signal. One end of the second resistor is connected to the output terminal of the control switch, and the other end of the second resistor is connected to the output terminal of the arc detection module; the reference terminal of the control switch is grounded; one end of the third resistor is connected between the first resistor and the control terminal of the control switch, and the other end of the third resistor is grounded.

4. The DC arc detection circuit according to claim 3, characterized in that, The self-test control signal includes a first self-test control signal. The drive module receives the first self-test control signal and outputs the first self-test feedback signal to the controller via the connection point between the output terminal of the arc detection module and the output terminal of the drive module. The first self-test control signal is an AC signal, and the first self-test feedback signal is a periodic signal. The controller performs feature analysis on the first self-test feedback signal and / or the controller calculates the actual magnetic inductance L of the current transformer. act This is to determine whether the arc detection module is functioning properly.

5. The DC arc detection circuit according to claim 4, characterized in that, The controller performs feature analysis on the first self-test feedback signal to determine whether the arc detection module is functioning properly, including at least one of the following: When the controller detects that the peak voltage of the first self-test feedback signal is within a preset peak range, it determines that the arc detection module is normally connected. The preset peak range is determined based on the normal peak voltage V. peak =V ref +I L0 *R s ; When the controller detects that the trough voltage of the first self-test feedback signal is within a preset trough range, it determines that the arc detection module is normally connected; wherein, the preset trough range is determined based on the normal trough voltage, and the normal trough voltage V valley =V ref -[(R s *R2) / (R s +R2)]*I L0 *e -(Rs / L)*T ; When the controller detects that the voltage amplitude of the first self-test feedback signal is within a preset amplitude range, it determines that the arc detection module is normally connected; wherein, the preset amplitude range is determined based on the difference between the normal peak voltage and the normal trough voltage; When the controller detects a high level in the first self-test feedback signal within a first preset voltage range, it determines that the arc detection module is disconnected. The first preset voltage range is determined based on an abnormal high level, where the abnormal high level V... g =V ref ; When the controller detects a low level in the first self-test feedback signal within a second preset voltage range, it determines that the arc detection module is disconnected. The second preset voltage range is determined based on an abnormal low level, where the abnormal low level V... d =V ref *[R2 / (R s +R2)]; Among them, V ref R is the reference voltage value. s R1 is the resistance value of the sampling resistor, R2 is the resistance value of the second resistor, and I L0 For steady-state inductor current, I L0 =V ref / R2, L is the theoretical magnetic inductance of the current transformer, and T is the duration of the control switch being turned off.

6. The DC arc detection circuit according to claim 3, characterized in that, The self-test control signal includes a first self-test control signal. The drive module receives the first self-test control signal and outputs the first self-test feedback signal to the controller via the connection point between the output terminal of the arc detection module and the output terminal of the drive module. The first self-test control signal is a high-level signal, and the first self-test feedback signal is a DC signal. The controller determines whether the arc detection module is functioning properly based on the voltage value of the first self-test feedback signal.

7. The DC arc detection circuit according to claim 6, characterized in that, The controller determines whether the arc detection module is functioning properly based on the voltage value of the first self-test feedback signal, including at least one of the following: When the controller detects that the voltage value of the first self-test feedback signal is within a third preset voltage range, it determines that the arc detection module is normally connected; wherein, the third preset voltage range is determined based on a normal voltage, and the normal voltage V z =V ref *{R2 / [R2+((R CT *R s ) / (R CT +R s ))]}; When the controller detects that the voltage value of the first self-test feedback signal is within a fourth preset voltage range, it determines that the arc detection module is disconnected; wherein, the fourth preset voltage range is determined based on an abnormal voltage, and the abnormal voltage V y =V ref *[R2 / (R s +R2)]; Among them, V ref R is the reference voltage value. CT R is the resistance value of the detection coil. s R1 is the resistance value of the sampling resistor, and R2 is the resistance value of the second resistor.

8. The DC arc detection circuit according to any one of claims 1-3, characterized in that, The self-test control signal includes a second self-test control signal. The drive module receives the second self-test control signal and outputs the second self-test feedback signal to the controller via the signal processing module. The second self-test control signal is an AC signal, and the second self-test feedback signal is a periodic signal. The controller performs feature analysis on the second self-test feedback signal to determine whether the signal processing module is functioning properly.

9. A DC arc detection method, applied to the DC arc detection circuit as described in any one of claims 1-8, characterized in that, include: The controller of the DC arc detection circuit generates a first self-test control signal; The controller acquires a first self-test feedback signal and determines whether the arc detection module of the DC arc detection circuit is normal based on the first self-test feedback signal; if the controller determines that the arc detection module is abnormal, it performs abnormal feedback; if the controller determines that the arc detection module is normal, it generates a second self-test control signal. The controller acquires a second self-test feedback signal and determines whether the signal processing module of the DC arc detection circuit is normal based on the second self-test feedback signal; if the controller determines that the signal processing module is abnormal, it provides abnormal feedback; if the controller determines that the signal processing module is normal, it determines that the DC arc detection circuit has passed the self-test.

10. An inverter, characterized in that, Includes a DC arc detection circuit as described in any one of claims 1-8.

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