Leakage current detection circuit and detection system for optical storage inverter
By designing a leakage current detection circuit including an AC sampling circuit, an oscillation circuit and a multi-stage filter circuit, the problem of insufficient leakage current recognition accuracy in the optical storage integrated inverter is solved, and higher detection accuracy and equipment reliability are achieved.
Patent Information
- Application Number
- CN202421133641.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-23
- Publication Date
- 2025-06-03
- Estimated Expiration
- 2034-05-23
AI Technical Summary
In the prior art, when the optical storage integrated inverter leaks with the metal casing part of the machine, the circuit does not have enough accuracy in identifying leakage current, resulting in a decrease in overall reliability.
A leakage current detection circuit including an AC sampling circuit, an oscillation circuit and a multi-stage filter circuit is designed. By sampling voltage signals and leakage current signals, a self-excited oscillation signal is generated and filtered to improve the accuracy of leakage current detection.
Through this detection circuit, the accuracy of the optical storage integrated machine for leakage current detection can be significantly improved, the reliability of the equipment can be enhanced, and safety hazards can be reduced.
Smart Images
Figure CN222939250U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of power supply protection, and particularly relates to a leakage current detection circuit and a detection system for a photovoltaic energy storage inverter. Background Art
[0002] The integrated photovoltaic energy storage inverter consists of three parts: a solar panel, a storage battery, and an inverter. Since there is a leakage phenomenon between the photovoltaic energy storage inverter and the metal casing of the machine, it is easy to damage the equipment. If the integrated photovoltaic energy storage machine does not have a leakage detection and protection circuit, it will pose a certain safety hazard to users. Through the leakage current detection circuit, the reliability of the integrated photovoltaic energy storage machine can be effectively improved. In the prior art, for the detection of leakage current, due to the insufficient accuracy of the circuit in identifying the leakage current, the overall reliability is reduced.
[0003] Therefore, in order to solve the technical problem of insufficient accuracy in identifying the leakage current caused by the circuit structure, it is necessary to design a leakage current detection circuit and a detection system. Summary of the Utility Model
[0004] In order to solve the technical problems mentioned in the background art, the utility model provides a leakage current detection circuit and a detection system for a photovoltaic energy storage inverter:
[0005] In a first aspect, the utility model provides a leakage current detection circuit, including:
[0006] An AC sampling circuit, whose three-phase input terminals are respectively electrically connected to the three-phase output terminals of the inverter, and the sampling voltage output terminal and the reference voltage terminal are respectively electrically connected to the corresponding ports of the control module;
[0007] An oscillation circuit, which is electrically connected to the leakage current output port of the inverter to generate a self-excited oscillation signal output by combining the leakage current signal; and
[0008] A multi-stage filtering circuit, whose input terminal is electrically connected to the oscillation circuit, and is used to filter the self-excited oscillation signal and output it to the control module.
[0009] Further, the oscillation circuit includes: a first oscillation circuit, a first voltage comparator, a second voltage comparator, a third voltage comparator, and an oscillation driving circuit; where
[0010] The output terminal of the first oscillation circuit is respectively electrically connected to the inverting terminal of the first voltage comparator and the non-inverting terminal of the second voltage comparator, and the non-inverting terminal of the first voltage comparator is electrically connected to the inverting terminal of the second voltage comparator; the output terminals of the first voltage comparator and the second voltage comparator are respectively connected to the non-inverting terminal and the inverting terminal of the third voltage comparator, and the output terminal of the third voltage comparator is connected to the oscillation driving circuit; and
[0011] The output terminal of the third voltage comparator and the output terminal of the first oscillation circuit are respectively connected to the leakage current output port of the inverter to form a leakage conduction loop.
[0012] Further, the oscillation circuit further includes: a second oscillation circuit, and the output terminal of the second oscillation circuit is electrically connected to the output terminal of the first oscillation circuit to form an oscillation signal summing terminal.
[0013] Further, the output terminal of the oscillation driving circuit is electrically connected to the input terminal of the multi-stage filtering circuit, and the oscillation signal summing terminal is electrically connected to the output terminal of the multi-stage filtering circuit;
[0014] The multi-stage filtering circuit includes: an RC high-pass filtering sub-circuit, a diode sub-circuit, and an RC low-pass filtering sub-circuit that are sequentially connected in series starting from the input terminal of the filtering circuit, and are connected to the control terminal of the filtering switch tube;
[0015] The first pole of the filtering switch tube is electrically connected to the oscillation signal summing terminal and then connected to the control module through a driving circuit.
[0016] Further, the AC sampling circuit includes: three single-phase sampling circuits with the same structure; where
[0017] The single-phase sampling circuit includes: a current sensor, and the sampling voltage output terminal of the current sensor is electrically connected to the corresponding port of the control module; and
[0018] The reference voltage output terminal of the current sensor is electrically connected to the corresponding port of the control module through a single-phase voltage follower.
[0019] In a second aspect, the present invention further provides a detection system for a photovoltaic energy storage inverter, including:
[0020] A leakage current detection unit for detecting the phase voltage signals of the inverter and filtering and oscillating the collected leakage current signals to generate a self-excited oscillation signal;
[0021] A control module, electrically connected to the corresponding output terminal of the leakage current detection unit, and outputting a control signal according to the obtained voltage signal and self-excited oscillation signal.
[0022] Further, the leakage current detection unit includes: an AC sampling circuit, an oscillation circuit, and a multi-stage filtering circuit; where
[0023] The three-phase input terminals of the AC sampling circuit are respectively electrically connected to the three-phase output terminals of the inverter, and the sampling voltage output terminal and the reference voltage terminal are respectively electrically connected to the corresponding ports of the control module;
[0024] The oscillation circuit is electrically connected to the leakage current output port of the inverter to generate and output a self-excited oscillation signal by combining the leakage current signal; and
[0025] The input end of the multi-stage filtering circuit is electrically connected to the oscillation circuit, and is used to filter the self-excited oscillation signal and output it to the control module.
[0026] Further, the oscillation circuit includes: a first oscillation circuit, a first voltage comparator, a second voltage comparator, a third voltage comparator, and an oscillation driving circuit; wherein
[0027] The output end of the first oscillation circuit is electrically connected to the inverting end of the first voltage comparator and the non-inverting end of the second voltage comparator respectively, and the non-inverting end of the first voltage comparator is electrically connected to the inverting end of the second voltage comparator; the output ends of the first voltage comparator and the second voltage comparator are respectively connected to the non-inverting end and the inverting end of the third voltage comparator, and the output end of this third voltage comparator is connected to the oscillation driving circuit; and
[0028] The output end of the third voltage comparator and the output end of the first oscillation circuit are respectively connected to the leakage current output port of the inverter to form a leakage conduction loop.
[0029] Further, the oscillation module further includes: a second oscillation circuit, and the output end of the second oscillation circuit is electrically connected to the output end of the first oscillation circuit to form an oscillation signal summing end.
[0030] Further, the input end of the multi-stage filtering circuit is electrically connected to the output end of the oscillation driving circuit, and its output end is electrically connected to the oscillation signal summing end;
[0031] The multi-stage filtering circuit includes: an RC high-pass filtering sub-circuit, a diode sub-circuit, and an RC low-pass filtering sub-circuit that are sequentially connected in series starting from the input end of the filtering circuit, and are connected to the control end of a filtering switch tube;
[0032] The first pole of the filtering switch tube is electrically connected to the oscillation signal summing end and then connected to the control module through a driving circuit.
[0033] Further, the AC sampling circuit includes: three single-phase sampling circuits with the same structure; wherein
[0034] The single-phase sampling circuit includes: a current sensor that obtains a single-phase current signal from the inverter, and the sampling voltage output end of the current sensor is electrically connected to the corresponding port of the control module; and
[0035] The reference voltage output end of the current sensor is electrically connected to the corresponding port of the control module through a single-phase voltage follower.
[0036] The beneficial effects of the present utility model are as follows. The present utility model obtains the sampling voltage signals of each phase and the self-excited oscillation signal related to the leakage current through the AC sampling circuit, the oscillation circuit and the multi-stage filtering circuit, so as to improve the overall detection accuracy of the leakage current by the subsequent control module.
[0037] Other features and advantages of the present utility model will be described in the subsequent description, and, in part, will become apparent from the description or will be understood by implementing the present utility model. The objectives and other advantages of the present utility model are achieved and obtained by the structures specifically pointed out in the description and the drawings.
[0038] In order to make the above-mentioned objectives, features and advantages of the present utility model more obvious and understandable, the following specifically provides preferred embodiments and, in conjunction with the accompanying drawings, the detailed description is as follows. Description of the Drawings
[0039] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0040] Figure 1 The circuit principle block diagram of the detection circuit involved in some embodiments is shown;
[0041] Figure 2 The circuit schematic diagram of the detection circuit involved in some embodiments is shown
[0042] Figure 3 The circuit schematic diagram of the oscillation circuit involved in some embodiments is shown;
[0043] Figure 4 The circuit schematic diagram of the multi-stage filtering circuit involved in some embodiments is shown;
[0044] Figure 5 The circuit schematic diagram of the AC sampling circuit involved in some embodiments is shown. Specific Embodiments
[0045] In order to make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the following will clearly and completely describe the technical solutions of the present utility model in conjunction with the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts fall within the scope of protection of the present utility model.
[0046] Such asFigure 1 and Figure 2 As shown in Figure 2 , at least one embodiment provides a leakage current detection circuit, including: an AC sampling circuit, whose three-phase input terminals are electrically connected to the three-phase output terminals of the inverter TX1 respectively, and whose sampling voltage output terminal and reference voltage terminal are electrically connected to the corresponding ports of the control module respectively; an oscillation circuit, which is electrically connected to the leakage current output port of the inverter TX1 to generate a self-excited oscillation signal output by combining the leakage current signal; and a multi-stage filtering circuit, whose input terminal is electrically connected to the oscillation circuit and is used to filter the self-excited oscillation signal and output it to the control module. Wherein the control module includes but is not limited to using a DSP controller.
[0047] In some embodiments, as Figure 3 shown in Figure 3 , the oscillation circuit includes: a first oscillation circuit, a first voltage comparator, a second voltage comparator, a third voltage comparator and an oscillation driving circuit; wherein the output terminal of the first oscillation circuit is electrically connected to the inverting terminal of the first voltage comparator and the non-inverting terminal of the second voltage comparator respectively, and the non-inverting terminal of the first voltage comparator is electrically connected to the inverting terminal of the second voltage comparator; the output terminals of the first voltage comparator and the second voltage comparator are respectively connected to the non-inverting terminal and the inverting terminal of the third voltage comparator, and the output terminal of this third voltage comparator is connected to the oscillation driving circuit; and the output terminal of the third voltage comparator and the output terminal of the first oscillation circuit are respectively connected to the leakage current output port of the inverter TX1 to form a leakage conduction loop.
[0048] In some embodiments, the oscillation circuit further includes: a second oscillation circuit, and the output terminal of the second oscillation circuit is electrically connected to the output terminal of the first oscillation circuit to form an oscillation signal summing terminal.
[0049] As Figure 4 shown in Figure 4 , the multi-stage filtering circuit includes: an RC high-pass filtering sub-circuit, a diode sub-circuit and an RC low-pass filtering sub-circuit; wherein the input terminal of the filtering circuit is electrically connected to the output terminal of the oscillation driving circuit; its output terminal is electrically connected to the oscillation signal summing terminal; and the RC high-pass filtering sub-circuit, the diode sub-circuit and the RC low-pass filtering sub-circuit are sequentially connected in series starting from the input terminal of the filtering circuit and are connected to the control terminal of the filtering switch tube; the first pole of the filtering switch tube is electrically connected to the oscillation signal summing terminal and then connected to the control module through a driving circuit.
[0050] In some embodiments, the RC high-pass filter sub-circuit is composed of a capacitor C21 and a resistor R34 grounded, the diode sub-circuit includes a diode D9, and the RC low-pass filter sub-circuit is composed of a resistor R31 and a capacitor C22 grounded. The filtering switch transistor can be a triode Q4. The base of the triode Q4 is electrically connected to the resistor R31 through an input resistor R30, and the emitter of the triode Q4 is grounded. Its collector is connected to a high level and then electrically connected to the oscillation signal aggregation terminal, and is connected to the input terminal of a driving circuit formed by an integrated operational amplifier U3D, that is, the input terminal of a voltage follower. The output terminal of the voltage follower is connected to the control module.
[0051] As Figure 5 shown, the AC sampling circuit includes: three single-phase sampling circuits with the same structure; taking the first phase as an example, the single-phase sampling circuit includes: a current sensor HCT1 that obtains a single-phase current signal from the inverter TX1, the sampling voltage output terminal Vout of the current sensor is electrically connected to the corresponding port of the control module; and the reference voltage output terminal Vref of the current sensor is electrically connected to the corresponding port of the control module through a single-phase voltage follower. The single-phase voltage follower is formed by an integrated operational amplifier U1A.
[0052] At least one embodiment provides a detection system for a photovoltaic energy storage inverter TX1, including: a leakage current detection unit for detecting the phase voltage signals of the inverter and filtering and oscillating the collected leakage current signals to generate a self-excited oscillation signal; a control module electrically connected to the corresponding output terminal of the leakage current detection unit, and outputting a control signal according to the obtained voltage signal and self-excited oscillation signal. The leakage current detection unit includes: an AC sampling circuit, an oscillation circuit, and a multi-stage filtering circuit; wherein the three-phase input terminals of the AC sampling circuit are respectively electrically connected to the three-phase output terminals of the inverter, and the sampling voltage output terminal and the reference voltage terminal are respectively electrically connected to the corresponding ports of the control module; the oscillation circuit is electrically connected to the leakage current output port of the inverter to generate and output a self-excited oscillation signal in combination with the leakage current signal; and the input terminal of the multi-stage filtering circuit is electrically connected to the oscillation circuit for filtering the self-excited oscillation signal and outputting it to the control module.
[0053] In some embodiments, the oscillation circuit includes: a first oscillation circuit, a first voltage comparator, a second voltage comparator, a third voltage comparator, and an oscillation driving circuit; wherein the output terminal of the first oscillation circuit is electrically connected to the inverting terminal of the first voltage comparator and the non-inverting terminal of the second voltage comparator, and the non-inverting terminal of the first voltage comparator is electrically connected to the inverting terminal of the second voltage comparator; the output terminals of the first voltage comparator and the second voltage comparator are respectively connected to the non-inverting terminal and the inverting terminal of the third voltage comparator, and the output terminal of the third voltage comparator is connected to the oscillation driving circuit; and the output terminal of the third voltage comparator and the output terminal of the first oscillation circuit are respectively connected to the leakage current output port of the inverter TX1 to form a leakage conduction loop.
[0054] In some embodiments, the oscillation module further includes: a second oscillation circuit, and the output terminal of the second oscillation circuit is electrically connected to the output terminal of the first oscillation circuit to form an oscillation signal summing terminal.
[0055] In some embodiments, the input terminal of the multi-stage filtering circuit is electrically connected to the output terminal of the oscillation driving circuit, and its output terminal is electrically connected to the oscillation signal summing terminal; the multi-stage filtering circuit includes: an RC high-pass filtering sub-circuit, a diode sub-circuit, and an RC low-pass filtering sub-circuit that are sequentially connected in series starting from the input terminal of the filtering circuit and are connected to the control terminal of the filtering switch tube; the first pole of the filtering switch tube is electrically connected to the oscillation signal summing terminal and then connected to the control module through a driving circuit.
[0056] In some embodiments, the AC sampling circuit includes: three single-phase sampling circuits with the same structure; wherein the single-phase sampling circuit includes: a current sensor that obtains a single-phase current signal from the inverter TX1, and the sampling voltage output terminal of the current sensor is electrically connected to the corresponding port of the control module; and the reference voltage output terminal of the current sensor is electrically connected to the corresponding port of the control module through a single-phase voltage follower, and the three single-phase voltage followers are respectively composed of the integrated operational amplifier U1A, the integrated operational amplifier U1B, and the integrated operational amplifier U1D.
[0057] As Figure 3As shown, for the oscillation circuit, the first oscillation circuit is composed of an operational amplifier U3B, a peripheral RC circuit, and a proportional operation circuit, and is electrically connected to the inverting terminal of the second voltage comparator and the non-inverting terminal of the third voltage comparator through a resistor R12 and a resistor R13. The second voltage comparator is composed of an operational amplifier U2A, and the third voltage comparator is composed of an integrated operational amplifier U2B. The output terminals of both are respectively connected to the non-inverting terminal and the inverting terminal of the third voltage comparator through a resistor R14 and a resistor R10. The third voltage comparator is composed of an integrated operational amplifier U3A, and the output terminal of this third voltage comparator is connected to the input terminal of the oscillation driving circuit. The oscillation driving circuit includes two transistors Q1 and Q2 arranged as a pair of transistors.
[0058] As Figure 3 shown, in some embodiments, the structure of the second oscillation circuit is similar to that of the first oscillation circuit and is composed of an integrated operational amplifier U3C.
[0059] As Figure 4 shown, in some embodiments, for the multi-stage filter circuit, the RC high-pass filter sub-circuit is composed of a capacitor C21 and a resistor R34 grounded, the diode sub-circuit includes a diode D9, and the RC low-pass filter sub-circuit is composed of a resistor R31 and a capacitor C22 grounded. The filter switching transistor can be a transistor Q4. The base of this transistor Q4 is electrically connected to the resistor R31 through an input resistor R30, and the emitter of the transistor Q4 is grounded. Its collector is connected to a high level and then electrically connected to the oscillation signal aggregation terminal and connected to the input terminal of a driving circuit composed of an integrated operational amplifier U3D, that is, the input terminal of a voltage follower. The output terminal of this voltage follower is connected to the control module.
[0060] The above specific circuit implementation methods are not the only ones shown in this embodiment and the accompanying drawings. Those skilled in the art can also form other module circuits with the same or similar functions according to the concept of this embodiment.
[0061] In the description of the present invention, it should be noted that the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0062] In several embodiments provided by this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are only illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. Also, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.
[0063] Taking the above-described ideal embodiments of the present utility model as inspiration, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this utility model. The technical scope of this utility model is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.
Claims
1. A leakage current detection circuit, characterized in that: include: An AC sampling circuit, wherein the three-phase input terminals are electrically connected to the three-phase output terminals of the inverter, and the sampling voltage output terminal and the reference voltage terminal are electrically connected to the corresponding ports of the control module; An oscillation circuit electrically connected to the leakage current output port of the inverter to generate a self-excited oscillation signal output in combination with the leakage current signal; as well as The multi-stage filtering circuit has an input end electrically connected to the oscillation circuit and is used to filter the self-excited oscillation signal and output it to the control module.
2. The leakage current detection circuit according to claim 1, characterized in that: The oscillation circuit comprises: a first oscillation circuit, a first voltage comparator, a second voltage comparator, a third voltage comparator and an oscillation driving circuit; wherein The output end of the first oscillation circuit is electrically connected to the inverting end of the first voltage comparator and the non-inverting end of the second voltage comparator, respectively, and the non-inverting end of the first voltage comparator is electrically connected to the inverting end of the second voltage comparator; the output ends of the first voltage comparator and the second voltage comparator are respectively connected to the non-inverting end and the inverting end of the third voltage comparator, and the output end of the third voltage comparator is connected to the oscillation driving circuit; and The output end of the third voltage comparator and the output end of the first oscillating circuit are respectively connected to the leakage current output port of the inverter to form a leakage conduction loop.
3. The leakage current detection circuit according to claim 2, characterized in that: The oscillation circuit further includes: a second oscillation circuit, wherein an output end of the second oscillation circuit is electrically connected to an output end of the first oscillation circuit to form an oscillation signal aggregation end.
4. The leakage current detection circuit according to claim 3, characterized in that: The output end of the oscillation driving circuit is electrically connected to the input end of the multi-stage filtering circuit, and the oscillation signal aggregation end is electrically connected to the output end of the multi-stage filtering circuit; The multi-stage filter circuit comprises: an RC high-pass filter subcircuit, a diode subcircuit and an RC low-pass filter subcircuit which are sequentially connected in series from the input end of the filter circuit and connected to the control end of the filter switch tube; The first electrode of the filter switch tube is electrically connected to the oscillation signal aggregation end and then connected to the control module through a driving circuit.
5. The leakage current detection circuit according to claim 1, characterized in that: The AC sampling circuit comprises: three single-phase sampling circuits with the same structure; The single-phase sampling circuit comprises: a current sensor, a sampling voltage output terminal of the current sensor being electrically connected to a corresponding port of the control module; and The reference voltage output terminal of the current sensor is electrically connected to a corresponding port of the control module through a single-phase voltage follower.
6. A detection system for a photovoltaic storage inverter, characterized in that: include: A leakage current detection unit, used to detect the voltage signals of each phase of the inverter and filter and oscillate the collected leakage current signals to generate self-excited oscillation signals; The control module is electrically connected to the corresponding output terminal of the leakage current detection unit, and outputs a control signal according to the obtained voltage signal and the self-excited oscillation signal.
7. The detection system according to claim 6, characterized in that: The leakage current detection unit comprises: an AC sampling circuit, an oscillation circuit and a multi-stage filtering circuit; wherein The three-phase input terminals of the AC sampling circuit are electrically connected to the three-phase output terminals of the inverter, and the sampling voltage output terminal and the reference voltage terminal are electrically connected to the corresponding ports of the control module; The oscillation circuit is electrically connected to the leakage current output port of the inverter to generate a self-excited oscillation signal output in combination with the leakage current signal; and The input end of the multi-stage filter circuit is electrically connected to the oscillation circuit, and is used to filter the self-excited oscillation signal and then output it to the control module.
8. The detection system according to claim 7, characterized in that: The oscillation circuit comprises: a first oscillation circuit, a first voltage comparator, a second voltage comparator, a third voltage comparator and an oscillation driving circuit; wherein The output end of the first oscillation circuit is electrically connected to the inverting end of the first voltage comparator and the non-inverting end of the second voltage comparator, respectively, and the non-inverting end of the first voltage comparator is electrically connected to the inverting end of the second voltage comparator; the output ends of the first voltage comparator and the second voltage comparator are respectively connected to the non-inverting end and the inverting end of the third voltage comparator, and the output end of the third voltage comparator is connected to the oscillation driving circuit; and The output end of the third voltage comparator and the output end of the first oscillating circuit are respectively connected to the leakage current output port of the inverter to form a leakage conduction loop.
9. The detection system according to claim 8, characterized in that: The oscillation module further includes: a second oscillation circuit, an output end of the second oscillation circuit is electrically connected to an output end of the first oscillation circuit to form an oscillation signal aggregation end.
10. The detection system according to claim 9, characterized in that: The input end of the multi-stage filter circuit is electrically connected to the output end of the oscillation drive circuit, and the output end thereof is electrically connected to the oscillation signal aggregation end; The multi-stage filter circuit comprises: an RC high-pass filter subcircuit, a diode subcircuit and an RC low-pass filter subcircuit which are sequentially connected in series from the input end of the filter circuit and connected to the control end of the filter switch tube; The first electrode of the filter switch tube is electrically connected to the oscillation signal aggregation end and then connected to the control module through a driving circuit.
11. The detection system according to claim 10, characterized in that: The AC sampling circuit comprises: three single-phase sampling circuits with the same structure; The single-phase sampling circuit comprises: a current sensor for acquiring a single-phase current signal from an inverter, wherein a sampling voltage output terminal of the current sensor is electrically connected to a corresponding port of a control module; and The reference voltage output terminal of the current sensor is electrically connected to a corresponding port of the control module through a single-phase voltage follower.