CN219085023U - Photovoltaic current sampling circuit and photovoltaic current sampling equipment - Google Patents
Photovoltaic current sampling circuit and photovoltaic current sampling equipment Download PDFInfo
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- CN219085023U CN219085023U CN202223553980.7U CN202223553980U CN219085023U CN 219085023 U CN219085023 U CN 219085023U CN 202223553980 U CN202223553980 U CN 202223553980U CN 219085023 U CN219085023 U CN 219085023U
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- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Abstract
The utility model relates to a photovoltaic current sampling circuit and photovoltaic current sampling equipment. The photovoltaic current sampling circuit comprises: the current divider is connected in series in an inversion current loop of the photovoltaic inverter and is used for collecting photovoltaic current of the photovoltaic inverter; the quantity of the isolation operational amplifier modules is the same as that of the current splitters, the input ends of the isolation operational amplifier modules are in one-to-one correspondence with the output ends of the current splitters, and the isolation operational amplifier modules are used for isolating and amplifying photovoltaic currents; the input end of the second-stage operational amplification module is connected with the output end of the isolation operational amplification module, and the second-stage operational amplification module is used for carrying out secondary amplification on the electric signals output by the isolation operational amplification module. At least two paths of independent sampling circuits are formed through at least two shunts, two isolation operational amplification modules and a two-stage operational amplification module, multipath sampling is carried out on the photovoltaic current, isolation operational amplification is carried out, the sampling interference is avoided, and the cost is saved.
Description
Technical Field
The utility model relates to the technical field of photovoltaics, in particular to a photovoltaic current sampling circuit and photovoltaic current sampling equipment.
Background
The photovoltaic inverter is used as an important device of a photovoltaic power generation system and plays an irreplaceable role in the process of converting direct current generated by photovoltaic power generation into commercial power. However, before the commercial power conversion, the dc current generated by the photovoltaic inverter needs to be sampled and detected, so as to ensure the normal operation of the commercial power conversion.
At present, the photovoltaic current is sampled in a single way, multiple ways of sampling cannot be achieved, and the cost is too high due to the fact that the Hall sensor is adopted for sampling in multiple ways of sampling.
Disclosure of Invention
In a first aspect, a photovoltaic current sampling circuit is provided, comprising:
the current divider is connected in series in an inversion current loop of the photovoltaic inverter and is used for collecting photovoltaic current of the photovoltaic inverter;
the quantity of the isolation operational amplifier modules is the same as that of the current splitters, the input ends of the isolation operational amplifier modules are in one-to-one correspondence with the output ends of the current splitters, and the isolation operational amplifier modules are used for isolating and amplifying photovoltaic currents;
the input end of the second-stage operational amplification module is connected with the output end of the isolation operational amplification module, and the second-stage operational amplification module is used for carrying out secondary amplification on the electric signals output by the isolation operational amplification module.
In one embodiment, the shunt includes:
the sampling resistor is connected in series in an inversion current loop of the photovoltaic inverter and is used for collecting photovoltaic current of the photovoltaic inverter.
In one embodiment, the sampling resistors of the shunt are at least two and are connected in parallel with each other.
In one embodiment, the method further comprises:
the input end of the first filtering module is connected with the output end of the shunt, and the output end of the first filtering module is connected with the input end of the isolation operational amplifier module.
In one embodiment, the method further comprises:
the input end of the second filtering module is connected with the output end of the power supply module, and the output end of the second filtering module is connected with the input power supply end of the isolation operational amplifier module.
In one embodiment, the method further comprises:
and the input end of the third filtering module is connected with the output end of the isolation operational amplifier module, and the third filtering module is used for filtering common-mode interference between the output ends of the isolation operational amplifier modules.
In one embodiment, the method further comprises:
and the input end of the feedback resistor is connected with the output end of the secondary operational amplification module, and the output end of the feedback resistor is connected with the input end of the secondary operational amplification module.
In one embodiment, the method further comprises:
and the input end of the overvoltage protection module is connected with the output end of the shunt, and the output end of the overvoltage protection module is connected with the input end of the isolation operational amplifier module.
In one embodiment, the overvoltage protection module includes:
the input end of the bidirectional trigger diode is connected with the output end of the shunt, and the output end of the bidirectional trigger diode is connected with the input end of the isolation operational amplifier module.
In a second aspect, a photovoltaic current sampling apparatus is provided, comprising a photovoltaic current sampling circuit according to any of the embodiments described above.
According to the photovoltaic current sampling circuit, at least two paths of independent sampling circuits are formed through the at least two current splitters, the two isolation operational amplifier modules and the two-stage operational amplifier module, multipath sampling is carried out on photovoltaic current, isolation operational amplifier is carried out, sampling interference is avoided, meanwhile, compared with the current sampling mode of adopting a Hall sensor, the cost is saved, and the size of a device is reduced.
Drawings
In order to more clearly illustrate the technical solutions of embodiments or conventional techniques of the present application, the drawings required for the descriptions of the embodiments or conventional techniques will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person of ordinary skill in the art.
FIG. 1 is a schematic diagram of a photovoltaic current sampling circuit according to an embodiment;
FIG. 2 is a schematic diagram of a photovoltaic current sampling circuit according to another embodiment;
fig. 3 is a schematic structural diagram of a photovoltaic current sampling circuit according to another embodiment.
Detailed Description
In order to facilitate an understanding of the present application, a more complete description of the present application will now be provided with reference to the relevant figures. Examples of the present application are given in the accompanying drawings. This application may, however, be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that the terms "first," "second," and the like, as used herein, may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another element. For example, a first resistance may be referred to as a second resistance, and similarly, a second resistance may be referred to as a first resistance, without departing from the scope of the present application. Both the first resistor and the second resistor are resistors, but they are not the same resistor.
It is to be understood that in the following embodiments, "connected" is understood to mean "electrically connected", "communicatively connected", etc., if the connected circuits, modules, units, etc., have electrical or data transfer between them.
As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," and/or the like, specify the presence of stated features, integers, steps, operations, elements, components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof.
In one embodiment, as shown in fig. 1, the photovoltaic current sampling circuit includes at least two shunts 102, at least two isolated op amp modules 104, and a two-stage op amp module 106. The current splitters 102 are all connected in series in an inverter current loop of the photovoltaic inverter, and the current splitters 102 are used for collecting photovoltaic current of the photovoltaic inverter. The number of the isolation operational amplifier modules 104 is the same as that of the current splitters 102, the input ends of the isolation operational amplifier modules 104 are in one-to-one correspondence with the output ends of the current splitters 102, and the isolation operational amplifier modules 104 are used for isolating and amplifying photovoltaic current. The input end of the second-stage operational amplification module 106 is connected with the output end of the isolation operational amplification module 104, and the second-stage operational amplification module 106 is used for performing secondary amplification on the electric signal output by the isolation operational amplification module 104.
The shunt 102 is an instrument for measuring a direct current, and is made according to the principle that a direct current generates a voltage across the device when passing through the device. The isolation op-amp module 104 may refer to an isolation op-amp chip, and a specific model thereof may be selected according to actual needs, for example, an isolation op-amp chip with a magnification of 8 times may be used in the present application. The two-stage operational amplifier module 106 may refer to an operational amplifier circuit or an operational amplifier chip composed of operational amplifiers.
Specifically, at least two shunts 102 are connected in series in an inverter current loop formed by the inverter power grid 100, voltage drops at two ends of the shunts 102 are measured, so that voltage of the shunts 102 is calculated, the voltage of each shunt 102 is input into an isolation operational amplifier corresponding to each shunt, and amplified voltage signals are obtained after isolation and amplification. Because the voltage signal amplified by the isolation operational amplifier module 104 has smaller amplitude, the voltage signal needs to be further amplified by the second-stage operational amplifier module 106 to meet the signal precision requirement and the amplitude requirement of the subsequent processor. It should be noted that, in the present application, only one second-stage operational amplification module 106 may be used to amplify signals input and output by the multiple isolation operational amplification modules 104, or an independent second-stage operational amplification module 106 is disposed at an output end of each isolation operational amplification module, and specific selection may be selected based on reasons such as cost, design convenience, and the like.
In the above embodiment, by forming the multi-path photovoltaic sampling circuit based on the shunt 102 and the isolation operational amplifier module 104, the cost is lower compared with the scheme of adopting the hall sensor to carry out multi-path adoption in the prior art, and the isolation operational amplifier module 104 is adopted to carry out isolation amplification in the multi-path adoption, so that the sampled signals are not interfered with each other, and the accuracy of the sampled signals is ensured.
In one embodiment, as shown in fig. 2, the shunt 102 includes a sampling resistor connected in series in the inverter current loop of the photovoltaic inverter, the sampling resistor being used to collect the photovoltaic current of the photovoltaic inverter.
The sampling resistor is generally divided into a plug-in resistor and a patch resistor according to the requirements of a specific circuit board. The sampling resistor has low resistance and high precision, and generally adopts 0.01% precision resistor when the precision of the resistance is within +/-1% and the application is more required. At present, most sampling resistors are plug-in resistors made of constantan and manganese copper. The resistance of the general sampling resistor can be selected below 1 ohm, and belongs to a milliohm non-inductive resistor.
In the embodiment, the sampling resistor is used for sampling the current and the voltage, so that the cost of the constructed photovoltaic current circuit is lower.
In one embodiment, the sampling resistances of the shunt 102 are at least two and are in parallel with each other.
At least two sampling resistors with the same resistance are connected in parallel, and the two sampling resistors are connected in parallel, so that the resistance actually connected in series in an inversion current loop is reduced, the current flowing through the sampling resistors is improved, and the sampling range is further improved. It should be noted that, except for increasing the sampling range by adopting a parallel connection mode, all modes capable of reducing the resistance value of the sampling resistor can increase the sampling range. If the sampling resistor with lower resistance value is adopted at first, the initial sampling range is increased, or the sampling range is increased by adopting a mode of connecting more sampling resistors in parallel.
In one embodiment, as shown in fig. 2, the circuit further includes a first filtering module 202. An input terminal of the first filtering module 202 is connected to an output terminal of the shunt 102, and an output terminal of the first filtering module 202 is connected to an input terminal of the isolation op-amp module 104.
The first filtering module 202 may refer to a filtering capacitor, and the accuracy of the transmission signal is ensured by filtering the voltage signal output by the shunt 102. Further, the selection of the filtering frequency band can be performed by adjusting the capacitance value of the filtering capacitor.
In the above embodiment, by filtering the signal input to the isolation op-amp module 104, interference of the noise is avoided, thereby affecting accuracy of the sampling result.
In one embodiment, as shown in fig. 2, the circuit further includes a second filtering module 204. An input end of the second filtering module 204 is connected to an output end of the power supply module 900, and an output end of the second filtering module 204 is connected to an input power supply end of the isolation op-amp module 104.
Here, the second filter module 204 may be referred to as a filter capacitor, and the power supply module 900 may be referred to as a dc power module. By filtering the dc power signal of the dc power module 900 that powers the isolated op-amp module 104, the ac voltage signal that exists in the dc voltage is prevented from affecting the operation performance of the electronic circuit, thereby improving the sampling accuracy.
In one embodiment, as shown in fig. 2, the circuit further includes a third filtering module 206. An input end of the third filtering module 206 is connected to an output end of the isolation op-amp module 104, and the third filtering module 206 is configured to filter out common mode interference between output ends of the isolation op-amp module 104.
The third wave module may also be referred to as a filter capacitor. The third filter capacitor filters the output signal of the isolation operational amplifier module 104 to remove a certain common mode interference, so as to ensure the accuracy of the signal input to the second-stage operational amplifier module 106.
In one embodiment, the circuit further comprises: and (5) feeding back the resistor. The input end of the feedback resistor is connected with the output end of the second-stage operational amplification module 106, and the output end of the feedback resistor is connected with the input end of the second-stage operational amplification module 106.
The resistance of the feedback resistor can be selected according to actual needs, and is not limited herein. The feedback resistor is used for forming a feedback circuit with the second-stage operational amplification module 106, and performing negative feedback adjustment in the process of performing second-stage operational amplification, so as to achieve the functions of improving gain stability, reducing nonlinear distortion, suppressing noise, expanding bandwidth and the like. It should be noted that, based on the specific implementation manner of negative feedback adjustment of the operational amplifier, a person skilled in the art can perform adaptive adjustment according to the prior art, which is not described herein.
In one embodiment, as shown in FIG. 2, an overvoltage protection module 208 is also included. An input terminal of the overvoltage protection module 208 is connected to an output terminal of the shunt 102, and an output terminal of the overvoltage protection module 208 is connected to an input terminal of the isolation op-amp module 104.
In the above embodiment, by providing the overvoltage protection module 208 between the shunt 102 and the isolation op-amp module 104, damage to the isolation op-amp module 104 and the subsequent secondary op-amp module 106 due to too high amplitude of the voltage signal input into the isolation op-amp module 104 is prevented.
In one embodiment, the overvoltage protection module 208 includes a diac. The input of the diac is connected to the output of the shunt 102 and the output of the diac is connected to the input of the isolated op-amp module 104.
The bidirectional trigger diode is an overvoltage protection device with low price and simple structure, and the cost of the sampling circuit can be further reduced by adopting the overvoltage protection device. In the actual circuit design, parameters and models of the diac may be adaptively selected according to the actual situation.
In one embodiment, a photovoltaic current sampling apparatus is provided comprising a photovoltaic current sampling circuit according to any of the embodiments described above.
To describe aspects of the present application in more detail, the following description is made in connection with specific electronic components in a photovoltaic sampling circuit. As shown in fig. 3, the figure is a path of sampling circuit in the photovoltaic sampling circuit, which is composed of a current divider, an isolation operational amplifier module and a two-stage operational amplifier module.
Here, the shunt is not shown in fig. 3. In an actual circuit, the current divider mainly refers to a sampling resistor, and two ends of the sampling resistor are respectively connected to a VIN+ end and a VIN-end in the isolation operational amplifier module U1, so that the input voltage to the isolation operational amplifier module U1 is calculated according to the voltage drop at two ends of the sampling resistor, and the magnitude of sampling current is obtained. The connection relationship between specific electronic components can be directly known from the drawings by those skilled in the art, and will not be described herein again, it should be noted that the model of the specific device in the drawings is only illustrated as an example, and the connection relationship is not limited in practical application and can be adjusted according to practical needs.
Specifically, two ends of the sampling resistor are respectively connected to two SOLAR1+ ends in the sampling circuit, and an input signal is respectively input to the VIN+ end and the VIN-end of the isolation operational amplifier module U1 through a bidirectional trigger diode D29 connected with the sampling resistor and a filter capacitor C37 in the first filter module. In the process, the filter capacitor C37 filters an input signal to prevent signal interference; the bidirectional trigger diode monitors the input signal, so that the damage of the whole circuit caused by the overlarge amplitude of the input signal is prevented, and the overvoltage protection function is realized. Further, a second filtering module is further disposed between the power supply module 900 (not shown in the figure) and the power supply input terminal VDD1 of the isolation op-amp module U1, and the filtering capacitor C43 of the second filtering module filters the direct current power supply signal of 5V, so as to avoid interference of the alternating current signal and influence normal operation of the electronic component. In addition, a filter capacitor C42 is further disposed between the output power supply terminal VDD2 of the isolation op-amp module U1 and the ground, and by filtering the ground signal, signal interference caused by the common ground terminal is avoided. After the isolation operational amplifier of the isolation operational amplifier module U1, an amplified output signal is obtained and is input into the second-stage operational amplifier module through the VOUT+ terminal and the VOUT-terminal. In the input process, the third filtering module arranged between the isolation operational amplifier module U1 and the second-stage operational amplifier module U7A is used for filtering, namely filtering is carried out through the filtering capacitors C45 and C46, and certain common-mode interference is filtered. Further, through the amplification of the second-stage operational amplification module U7A, the feedback circuit formed by the feedback resistor R162, the resistor R165, the resistor R166 and the resistor R168 is used for carrying out negative feedback adjustment based on the principle of virtual short and virtual break of the second-stage operational amplification module U7A, so that the output of the second-stage operational amplification module U7A is adjusted, and the accuracy and the amplitude of an output signal are guaranteed to meet the actual demands.
In the above embodiment, a path of sampling circuit formed by a current divider, an isolation operational amplifier module and a two-stage operational amplifier module is matched with other functional modules to form a low-cost sampling circuit, and on the basis, the collection of multiple paths of photovoltaic currents can be realized at low cost by arranging multiple paths of similar sampling circuits.
In the description of the present specification, reference to the terms "some embodiments," "other embodiments," "desired embodiments," and the like, means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the utility model. In this specification, schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the utility model, which are described in detail and are not to be construed as limiting the scope of the utility model. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the utility model, which are all within the scope of the utility model. Accordingly, the scope of protection of the present utility model is to be determined by the appended claims.
Claims (10)
1. A photovoltaic current sampling circuit, comprising:
the current divider is connected in series in an inversion current loop of the photovoltaic inverter and is used for collecting photovoltaic current of the photovoltaic inverter;
the quantity of the isolation operational amplifier modules is the same as that of the shunts, the input ends of the isolation operational amplifier modules are in one-to-one correspondence with the output ends of the shunts, and the isolation operational amplifier modules are used for isolating and amplifying the photovoltaic current;
the input end of the second-stage operational amplification module is connected with the output end of the isolation operational amplification module, and the second-stage operational amplification module is used for carrying out secondary amplification on the electric signals output by the isolation operational amplification module.
2. The photovoltaic current sampling circuit of claim 1, wherein the shunt comprises:
the sampling resistor is connected in series in an inversion current loop of the photovoltaic inverter and is used for collecting photovoltaic current of the photovoltaic inverter.
3. The photovoltaic current sampling circuit of claim 2, wherein the sampling resistances of the current divider are at least two and are in parallel with each other.
4. The photovoltaic current sampling circuit of claim 1, further comprising:
the input end of the first filtering module is connected with the output end of the shunt, and the output end of the first filtering module is connected with the input end of the isolation operational amplifier module.
5. The photovoltaic current sampling circuit of claim 1, further comprising:
the input end of the second filtering module is connected with the output end of the power supply module, and the output end of the second filtering module is connected with the input power supply end of the isolation operational amplifier module.
6. The photovoltaic current sampling circuit of claim 1, further comprising:
the input end of the third filtering module is connected with the output end of the isolation operational amplifier module, and the third filtering module is used for filtering common-mode interference between the output ends of the isolation operational amplifier module.
7. The photovoltaic current sampling circuit of claim 1, further comprising:
and the input end of the feedback resistor is connected with the output end of the secondary operational amplification module, and the output end of the feedback resistor is connected with the input end of the secondary operational amplification module.
8. The photovoltaic current sampling circuit of claim 1, further comprising:
and the input end of the overvoltage protection module is connected with the output end of the shunt, and the output end of the overvoltage protection module is connected with the input end of the isolation operational amplifier module.
9. The photovoltaic current sampling circuit of claim 8, wherein the overvoltage protection module comprises:
the input end of the bidirectional trigger diode is connected with the output end of the shunt, and the output end of the bidirectional trigger diode is connected with the input end of the isolation operational amplifier module.
10. A photovoltaic current sampling apparatus comprising a photovoltaic current sampling circuit according to any one of claims 1 to 9.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202223553980.7U CN219085023U (en) | 2022-12-28 | 2022-12-28 | Photovoltaic current sampling circuit and photovoltaic current sampling equipment |
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| CN202223553980.7U CN219085023U (en) | 2022-12-28 | 2022-12-28 | Photovoltaic current sampling circuit and photovoltaic current sampling equipment |
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| CN219085023U true CN219085023U (en) | 2023-05-26 |
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| CN202223553980.7U Active CN219085023U (en) | 2022-12-28 | 2022-12-28 | Photovoltaic current sampling circuit and photovoltaic current sampling equipment |
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Address after: Leyitong Industrial Park, No. 16 Dongsheng South Road, Chenjiang Street, Zhongkai High tech Zone, Huizhou City, Guangdong Province, 516000 Patentee after: Huizhou Leyitong Technology Co.,Ltd. Address before: 516000 building a, industrial building, No.53, huitai Industrial Park, Zhongkai high tech Zone, Huizhou City, Guangdong Province Patentee before: HUIZHOU LEYITONG TECHNOLOGY CO.,LTD. |