Current sampling device and IV test equipment

Abstract

The utility model provides a current sampling device and IV test equipment. The current sampling device comprises a resistance sampling module, a multi-gear amplification module, an output module and a controller, the resistance sampling module and the photovoltaic cell are connected in series in a loop; the first end of the multi-gear amplification module is connected with the resistance sampling module, the second end of the multi-gear amplification module is connected with the output module, and the third end of the multi-gear amplification module is connected with the controller; and the controller controls the multi-gear amplification module to perform multi-gear switching of different amplification factors. By adopting the scheme, layout and wiring can be simplified, the use of sampling resistors can be reduced, and the cost is reduced.

Description

Technical Field

[0001] This application relates to the field of photovoltaic testing technology, and in particular to a current sampling device and IV testing equipment. Background Technology

[0002] IV testing (current-voltage testing) is a common testing method for photovoltaic (PV) testing. IV testing involves connecting a photovoltaic cell (PV) to an IV testing device, which samples the current and voltage. Then, based on the collected data, photoelectric performance parameters are extracted to evaluate the photoelectric performance.

[0003] Current sampling is generally achieved by sampling with a sampling resistor, followed by processing and output. To achieve multi-range testing, the current method uses multiple sampling resistors to achieve different measurement ranges. By switching between different sampling resistors, the current range can be switched to obtain different current ranges for testing. However, more sampling resistors result in more sampling channels, leading to circuit complexity, increased layout difficulty, and higher costs. Utility Model Content

[0004] This application provides a current sampling device and an IV testing device to solve the above-mentioned technical problems in the prior art.

[0005] According to a first aspect of this application, a current sampling device is provided for sampling the current of a photovoltaic cell during IV testing. The device includes: a resistance sampling module, a multi-level amplification module, an output module, and a controller.

[0006] The resistance sampling module is connected in series with the photovoltaic cell in the circuit;

[0007] The first end of the multi-level amplification module is connected to the resistance sampling module, the second end of the multi-level amplification module is connected to the output module, and the third end of the multi-level amplification module is connected to the controller.

[0008] The controller controls the multi-level amplification module to switch between different amplification levels.

[0009] In some embodiments, the current sampling device further includes a primary amplification module connected between the resistance sampling module and the multi-level amplification module.

[0010] In some embodiments, the resistance sampling module includes a first resistor, a second resistor, and a switching circuit, and the primary amplification module includes a first primary amplifier, a second primary amplifier, and a switching circuit, wherein the resistance values ​​of the first resistor and the second resistor are different;

[0011] The first resistor and the second resistor are both connected in series in the circuit where the photovoltaic cell is located, and the switching circuit is connected in parallel across the two ends of the second resistor / first resistor and connected to the controller;

[0012] The first primary amplifier is connected to both ends of the first resistor and is connected to the multi-stage amplifier module through the switching circuit;

[0013] The second primary amplifier is connected to both ends of the second resistor and is connected to the multi-level amplifier module through the switching circuit;

[0014] The switching circuit is connected to the controller, which controls the on / off state of the switching circuit and controls the switching circuit to connect to the multi-level amplification module by selecting one of the first primary amplifier and the second primary amplifier.

[0015] In some embodiments, the switching circuit includes a MOSFET, a first terminal of which is connected to one end of the second resistor / first resistor, a second terminal of which is connected to the other end of the second resistor / first resistor, and a control terminal of which is connected to the controller.

[0016] In some embodiments, the switching circuit includes a first switch and a second switch, a first end of the first switch is connected to the first primary amplifier, a second end of the first switch is connected to the multi-level amplifier module, and a control end of the first switch is connected to the controller.

[0017] The first end of the second switch is connected to the second primary amplifier, the second end of the second switch is connected to the multi-level amplifier module, and the control end of the second switch is connected to the controller.

[0018] In some embodiments, the resistance sampling module includes a first resistor, a second resistor, and a switching circuit;

[0019] The first resistor and the second resistor are connected in parallel, and their parallel connection point is connected in series in the circuit where the photovoltaic cell is located. The multi-level amplification module is connected to the parallel connection point of the first resistor and the second resistor.

[0020] The resistance value of the first resistor is less than that of the second resistor, and the switching circuit is provided at least on a branch of the first resistor, with the control terminal of the switching circuit connected to the controller;

[0021] The controller controls the switching circuit to open and close.

[0022] In some embodiments, the multi-level amplification module includes an amplifier, a plurality of gain control resistors, and a switch corresponding to at least one gain control resistor.

[0023] The first end of the amplifier serves as the first end of the multi-level amplification module, and is connected to the resistance sampling module; the second end of the amplifier serves as the second end of the multi-level amplification module, and is connected to the output module.

[0024] Multiple gain control resistors are connected in parallel in the gain control circuit of the amplifier. The first terminal of the switch is connected to one end of the corresponding gain control resistor. The second terminal of the switch is connected to the parallel junction of the multiple gain control resistors. The control terminal of the switch serves as the third terminal of the multi-level amplification module, and is connected to the controller.

[0025] In some embodiments, the output module includes an analog-to-digital converter connected to the multi-amplifier module.

[0026] In some embodiments, the output module further includes a single-ended to differential circuit connected between the multi-level amplifier module and the analog-to-digital converter.

[0027] According to a second aspect of this application, an IV testing device is provided, including the aforementioned current sampling device.

[0028] In summary, the current sampling device and IV testing equipment provided in this application have at least the following beneficial effects:

[0029] By employing a resistor sampling module for current sampling, and then amplifying the signal output from the resistor sampling module using a multi-level amplification module before outputting it by the output module, the amplification factor of the multi-level amplification module is switched by a controller. Different amplification factors amplify the signal to different ranges and correspond to different levels, thereby refining the current sampling range for use in current testing of different ranges. This eliminates the need for multiple sampling circuits for switching, resulting in a simple structure that simplifies layout and wiring, reduces the use of sampling resistors, and lowers costs. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the specific embodiments of this application, the accompanying drawings used in the specific embodiments will be briefly introduced below in conjunction with the accompanying drawings. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings or solutions can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a structural block diagram of a current sampling device in one embodiment of this application;

[0032] Figure 2 This is a structural diagram of the current sampling device in another embodiment of this application;

[0033] Figure 3 This is a circuit diagram of the resistance sampling module in one embodiment of this application;

[0034] Figure 4 This is a structural diagram of the current sampling device in another embodiment of this application. Detailed Implementation

[0035] In the description of this application, it should be understood that the use of terms such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" to indicate orientation or positional relationship, unless otherwise specified, is understood to be based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0036] Furthermore, features specified with "first" or "second" for descriptive purposes only should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Features specified with "first" or "second" may explicitly or implicitly include at least one of the specified features. The description of "multiple" generally means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0037] In this application, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can be a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0038] In the description of this specification, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0039] In one embodiment of this application, a current sampling device is provided for sampling the current during IV testing of a photovoltaic cell. (Reference) Figure 1 The current sampling device includes: a resistance sampling module 110, a multi-level amplification module 130, an output module 150, and a controller 170.

[0040] In this circuit, the resistance sampling module 110 is connected in series with the photovoltaic cell. For example... Figure 1 In this circuit, the power supply C, the load, and the resistance sampling module 110 are connected in series to form a loop. Specifically, under different test conditions, the photovoltaic cell can act as either the power supply C or the load. For example, during a test with illumination, the photovoltaic cell acts as the power supply C, supplying power to the loop connecting the load and the resistance sampling module 110 in series. During a test without illumination, an external power supply device is used as the power supply C, and the photovoltaic cell acts as the load. The power supply C supplies power to the loop connecting the photovoltaic cell and the resistance sampling module 110 in series. The resistance sampling module 110 is connected in series in the loop containing the photovoltaic cell, so that the current sampled by the resistance sampling module 110 varies with the current of the photovoltaic cell. The resistance sampling module 110 includes a resistor for current sampling.

[0041] The first terminal of the multi-level amplifier module 130 is connected to the resistor sampling module 110, the second terminal of the multi-level amplifier module 130 is connected to the output module 150, and the third terminal of the multi-level amplifier module 130 is connected to the controller 170. The multi-level amplifier module 130 amplifies the voltage input at the first terminal and outputs it to the output module 150. The voltage amplification factor is related to the current level of the multi-level amplifier module 130; different levels correspond to different amplification factors.

[0042] Specifically, the controller 170 controls the multi-level amplification module 130 to switch between different amplification factors at multiple levels. That is, under the control of the controller 170, the multi-level amplification module 130 can switch to different levels to change the amplification factor, thereby adjusting the voltage range of the output voltage and realizing the level adjustment of current sampling. The controller 170 can be an MCU (microprocessor unit) inside the IV testing equipment. Specifically, under different testing requirements, the controller 170 can output different level signals to the multi-level amplification module 130 to achieve level switching. For example, the user can set the measurement level on the host computer according to the maximum current to be tested. The host computer sends a control signal to the controller 170 based on the set level, and the controller 170 outputs a level signal corresponding to the control signal to the multi-level amplification module 130, causing the multi-level amplification module 130 to switch to the corresponding level.

[0043] Furthermore, the voltage output by the output module 150 is used to obtain the sampled current value. For example, the output module 150 can also be connected to the controller 170, and the output module 150 outputs voltage to the controller 170, which can obtain the corresponding sampled current value based on the output voltage.

[0044] The aforementioned current sampling device uses a resistor sampling module 110 to sample the current. The multi-level amplification module 130 amplifies the signal output from the resistor sampling module 110 and outputs it through the output module 150. The controller 170 controls the switching of the amplification factor of the multi-level amplification module 130. Different amplification factors amplify the signal to different ranges and correspond to different levels, thereby refining the current sampling levels for use in current testing of different ranges. It does not require multiple sampling circuits for switching, has a simple structure, facilitates simplified layout and wiring, and reduces the use of sampling resistors, thus lowering costs.

[0045] In one embodiment, the current sampling device further includes a primary amplification module connected between the resistance sampling module 110 and the multi-range amplification module 130. That is, the first end of the primary amplification module is connected to the resistance sampling module 110, and the second end of the primary amplification module is connected to the first end of the multi-range amplification module 130.

[0046] The primary amplification module is used to initially amplify the signal output from the resistor sampling module 110, adjusting the small signal to a suitable amplitude at the source end for secondary amplification by the multi-level amplification module 130. Specifically, the amplification factor of the primary amplification module is fixed, which simplifies the circuit structure. It is understood that in other embodiments, the primary amplification module may also be an amplification module with multiple levels.

[0047] In one embodiment, the distance between the primary amplification module and the resistance sampling module 110 is less than a preset value. This preset value can be set to a small value. The smaller the distance between the primary amplification module and the resistance sampling module 110, the closer the primary amplification module is to the resistance sampling module 110, and thus closer to the resistor used for sampling within the resistance sampling module 110. Since the source signal output by the resistance sampling module 110 is small, the source voltage input to the primary amplification module is also small, typically tens of millivolts, making it susceptible to interference. The closer the primary amplification module is to the resistance sampling module 110, the less interference is introduced. Therefore, by placing the primary amplification module close to the resistance sampling module 110, interference can be reduced and sampling accuracy improved.

[0048] In one embodiment, reference Figure 2 The resistance sampling module 110 includes a first resistor R1, a second resistor R2, and a switching circuit 111. The primary amplification module includes a first primary amplifier 121, a second primary amplifier 122, and a switching circuit 123. The first resistor R1 and the second resistor R2 have different resistance values; both are precision sampling resistors.

[0049] The first resistor R1 and the second resistor R2 are connected in series, and both are connected in series in the circuit containing the photovoltaic cell. Figure 2 In this test, the photovoltaic cell can act as either a power source (C) or a load, depending on the specific test conditions. For example, during a test with illumination, the photovoltaic cell acts as power source C, supplying power to the circuit connected in series between the load and the resistance sampling module 110. During a test without illumination, an external power supply is used as power source C, and the photovoltaic cell acts as the load. The switching circuit 111 is connected in parallel across the second resistor R2 or the first resistor R1 and is connected to the controller 170. The controller 170 can control the on / off state of the switching circuit 111 by outputting switch control commands (such as control level signals).

[0050] Specifically, the switch circuit 111 is connected in parallel across the larger of the first resistor R1 and the second resistor R2. For example... Figure 2Since the resistance of the second resistor R2 is greater than that of the first resistor R1, the switch circuit 111 is connected in parallel across the second resistor R2. When the switch circuit 111 is open, both the first resistor R1 and the second resistor R2 are connected in series in the circuit containing the photovoltaic cell. The resistance in this circuit is relatively high, and the current is relatively low, representing the small current sampling range. When the switch circuit 111 is closed, the first resistor R1, with its lower resistance, is connected in series in the circuit containing the photovoltaic cell. The resistance in this circuit is relatively low, and the current is relatively high, representing the large current sampling range. Therefore, by controlling the on / off state of the switch circuit 111 through the controller 170, the current magnitude in the circuit can be switched, thereby achieving the switching between large and small current sampling ranges. In both the small and large current ranges switched by the switch circuit 111, the multi-level amplification module 130 can select different amplification factors, thus obtaining multiple levels under both the small and large current ranges, further refining the sampling range. Specifically, the host computer sends a control signal to the controller 170 according to the user-set gear level. The controller 170 outputs two different level signals corresponding to the control signal to the switching circuit 111 and the multi-level amplifier module 130 to select the corresponding sampling gear level. It can be understood that in other embodiments, the resistance value of the first resistor R1 may be greater than that of the second resistor R2, and the switching circuit 111 may be connected in parallel across the first resistor R1.

[0051] Specifically, the first primary amplifier 121 is connected across the first resistor R1, and the second primary amplifier 122 is connected across the second resistor R2; the amplification factors of the first primary amplifier 121 and the second primary amplifier 122 are different. The first primary amplifier 121 samples and amplifies the voltage across the first resistor R1, and the second primary amplifier 122 samples and amplifies the voltage across the second resistor R2. Thus, each of the two sampling resistors is connected to a primary amplifier for primary amplification of the corresponding signal. Furthermore, the first primary amplifier 121 is positioned close to the first resistor R1, and the second primary amplifier 122 is positioned close to the second resistor R2 to reduce signal interference.

[0052] Both the first primary amplifier 121 and the second primary amplifier 122 are connected to the multi-range amplifier module 130 via a switching circuit 123, which is connected to a controller 170. Specifically, the controller 170 controls the switching circuit 123 to selectively connect one of the first primary amplifier 121 and the second primary amplifier 122 to the multi-range amplifier module 130. For example, when the switch circuit 111 is connected across the second resistor R2, and the controller 170 controls the switch circuit 111 to close, the system operates at the high current sampling range, and the controller 170 controls the switching circuit 123 to connect the first primary amplifier 121 and the multi-range amplifier module 130. When the controller 170 controls the switch circuit 111 to open, the system operates at the low current sampling range, and the controller 170 controls the switching circuit 123 to connect the second primary amplifier 122 and the multi-range amplifier module 130.

[0053] By employing two resistors connected in series, each corresponding to a primary amplifier, the switching circuit 111 controls the switching of resistance values ​​in the circuit. Simultaneously, the switching circuit 123 switches the corresponding channels to connect to the multi-level amplification module 130, thereby further dividing the sampling into high-current and low-current ranges. In both high-current and low-current ranges, the amplification factor of the multi-level amplification module 130 can be adjusted. Thus, different amplification factors can be used to achieve different ranges in the high-current range and in the low-current range, resulting in more refined sampling ranges for current sampling and testing, thereby improving the accuracy of current testing.

[0054] It is understood that in embodiments without a primary amplification module, the multi-stage amplification module 130 can be connected to both ends of the first resistor R1 or to both ends of the second resistor R2.

[0055] Specifically, the first primary amplifier 121 and the second primary amplifier 122 may include an instrumentation amplifier and a gain resistor (see reference). Figure 4 The gain resistor is connected in the gain control circuit of the instrumentation amplifier to achieve automatic gain control.

[0056] In one embodiment, the switching circuit 111 includes a MOSFET. The first terminal of the MOSFET is connected to one end of the second resistor R2 / first resistor R1, and the second terminal of the MOSFET is connected to the other end of the second resistor R2 / first resistor R1. The control terminal of the MOSFET is connected to the controller 170. MOSFETs have low power consumption and long lifespan. By using MOSFETs for switching between different current levels, overall power consumption can be reduced and lifespan can be extended.

[0057] It is understandable that the switching circuit 111 can use one or more MOS transistors, and multiple MOS transistors can form a switching structure, such as a PMOS transistor and an NMOS transistor connected in parallel.

[0058] In one embodiment, reference Figure 2 The switching circuit 123 includes a first switch K1 and a second switch K2. The first end of the first switch K1 is connected to the first primary amplifier 121, the second end of the first switch K1 is connected to the multi-level amplifier module 130, and the control end of the first switch K1 is connected to the controller 170. The first end of the second switch K2 is connected to the second primary amplifier 122, the second end of the second switch K2 is connected to the multi-level amplifier module 130, and the control end of the second switch K2 is connected to the controller 170.

[0059] The controller 170 controls the switching of the first switch K1 and the second switch K2 to allow one of the first primary amplifier 121 and the second primary amplifier 122 to connect to the multi-stage amplifier module 130. Specifically, when the controller 170 controls the first switch K1 to be closed and the second switch K2 to be open, the first primary amplifier 121 is electrically connected to the multi-stage amplifier module 130 through the first switch K1; when the controller 170 controls the first switch K1 to be open and the second switch K2 to be closed, the second primary amplifier 122 is electrically connected to the multi-stage amplifier module 130 through the second switch K2. Thus, channel switching is achieved using only two switches, resulting in a simple structure.

[0060] In another embodiment, reference Figure 3 The resistance sampling module 110 includes a first resistor R1, a second resistor R2, and a switching circuit 111. The first resistor R1 and the second resistor R2 are connected in parallel, and their parallel junction is connected in series in the circuit containing the photovoltaic cell. Figure 3 During the test with illumination, the photovoltaic cell acts as the power source C; during the test without illumination, the light source cell acts as the load. The multi-stage amplification module 130 is connected to the parallel connection of the first resistor R1 and the second resistor R2, that is, the multi-stage amplification module 130 is connected to the two ends of the parallel connection of the first resistor R1 and the second resistor R2.

[0061] The resistance of the first resistor R1 is less than that of the second resistor R2, and a switching circuit 111 is provided at least in the branch of the first resistor R1. A switching circuit 111 can also be provided in the branch of the second resistor R2 (e.g., Figure 3(As shown), the switch circuit 111 can also be omitted. The control terminal of the switch circuit 111 is connected to the controller 170. The controller 170 controls the on / off state of the switch circuit 111 to control whether the resistor in the branch where the switch circuit 111 is located is connected to the circuit where the photovoltaic cell is located. This switches the total resistance between the two parallel nodes of the first resistor R1 and the second resistor R2, that is, switches the resistance in the circuit where the photovoltaic cell is located, thereby switching the current sampling through the resistor. In this way, the division of large and small current ranges can also be achieved by using two resistors in parallel. Specifically, when the branch where the first resistor R1 is located is open and the branch where the second resistor R2 is located is closed, it operates in the small current sampling range; when both the branches where the first resistor R1 and the second resistor R2 are located are closed, or when the branch where the first resistor R1 is located is closed and the branch where the second resistor R2 is open, it operates in the large current sampling range.

[0062] For example, the first resistor R1 can be a small resistor of 10mΩ, and the second resistor R2 can be a large resistor of 1Ω. Figure 3 As shown, the first switch circuit 111 is connected to the branch of the first resistor R1, and the second switch circuit 111 is connected to the branch of the second resistor R2. When the controller 170 controls both switch circuits 111 to be closed, the first resistor R1 and the second resistor R2 are connected in parallel to the circuit. When the controller 170 controls the first switch circuit 111 to be open and the second switch circuit 111 to be closed, only the second resistor R2 is connected to the circuit. The parallel resistance of the two resistors is less than the resistance of the second resistor R2. Therefore, when both switch circuits 111 are closed, the circuit operates at the high current sampling range, and when the first switch circuit 111 is open and the second switch circuit 111 is closed, the circuit operates at the low current sampling range.

[0063] In one embodiment, the multi-level amplifier module 130 includes an amplifier, a plurality of gain control resistors, and a switch corresponding to at least one gain control resistor. That is, all gain control resistors may be connected to a single switch, or only a portion of the gain control resistors may be connected to a single switch. The first terminal of the amplifier serves as the first terminal of the multi-level amplifier module 130, connected to the resistance sampling module 110; specifically, if the resistance sampling module 110 and the multi-level amplifier module 130 are connected to a primary amplifier module, then the first terminal of the amplifier is connected to the primary amplifier module, for example... Figure 3 The intermediate amplifier is an instrumentation amplifier, and its first terminal is connected to the instrumentation amplifier in the primary amplification module. The second terminal of the amplifier serves as the second terminal of the multi-stage amplification module 130, and is connected to the output module 150.

[0064] Multiple gain control resistors are connected in parallel in the amplifier's gain control circuit; that is, multiple gain control resistors are connected in parallel and then connected in the amplifier's gain control circuit. The first terminal of the switch is connected to one end of the corresponding gain control resistor, and the second terminal of the switch is connected to the parallel junction of the multiple gain control resistors; that is, the switch is connected in series in the branch containing the corresponding gain control resistor. The control terminal of the switch serves as the third terminal of the multi-level amplifier module 130, connecting to the controller 170. Specifically, the controller 170 controls the on / off state of the switch to control whether the gain control resistor connected to the switch is connected to the gain control circuit, thereby controlling the gain to achieve switching of the amplification factor. The structure is simple and easy to implement.

[0065] refer to Figure 4 Taking three gain control resistors, each connected to a corresponding switch, as an example, the controller 170 uses an MCU. The branch containing gain control resistor R3 and switch K3 is the first branch, the branch containing gain control resistor R4 and switch K4 is the second branch, and the branch containing gain control resistor R5 and switch K5 is the third branch. The MCU controls the on / off state of switches K3, K4, and K5 to control whether the first, second, and third branches are connected to the gain control circuit, that is, to control the overall gain resistance, thereby controlling the overall amplification factor. One amplification factor corresponds to one level.

[0066] In one embodiment, the output module 150 includes an analog-to-digital converter (ADC) connected to the multi-amplifier module 130. By employing the ADC, the sampled analog signal is converted into a digital signal for output, facilitating subsequent data processing. Specifically, the ADC can be a differential ADC.

[0067] In one embodiment, the output module 150 further includes a single-ended to differential converter connected between the multi-amplifier module 130 and the analog-to-digital converter. By adding a single-ended to differential converter before the analog-to-digital converter, the common-mode interference of the circuit is reduced.

[0068] For example Figure 4 As shown, the analog-to-digital converter uses a differential ADC, and a single-ended to differential circuit is added to the front end of the differential ADC. The instrumentation amplifier in the multi-stage amplifier module 130 is connected to the single-ended to differential circuit.

[0069] In addition, this application provides an IV testing device, including the current sampling device in the above embodiments.

[0070] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, provided that such combination does not contain contradictions.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A current sampling device for sampling the current during IV testing of a photovoltaic cell, characterized in that, The device comprises a resistance sampling module, a multi-gear amplification module, an output module and a controller; The resistance sampling module is connected in series with the photovoltaic cell in a loop; The first end of the multi-gear amplification module is connected with the resistance sampling module, the second end of the multi-gear amplification module is connected with the output module, and the third end of the multi-gear amplification module is connected with the controller; The controller controls the multi-gear amplification module to switch different amplification multiples.

2. The current sampling device of claim 1, wherein, A primary amplification module is further included, which is connected between the resistance sampling module and the multi-gear amplification module.

3. The current sampling device of claim 2, wherein, The resistance sampling module comprises a first resistor, a second resistor and a switch circuit, the primary amplification module comprises a first primary amplifier, a second primary amplifier and a switch circuit, the first resistor and the second resistor have different resistance values, and the first primary amplifier and the second primary amplifier have different amplification multiples; The first resistor and the second resistor are both connected in series in the loop where the photovoltaic cell is located, and the switch circuit is connected across the second resistor / the first resistor and connected with the controller; The first primary amplifier is connected across the first resistor and connected with the multi-gear amplification module through the switch circuit; The second primary amplifier is connected across the second resistor and connected with the multi-gear amplification module through the switch circuit; The switch circuit is connected with the controller, the controller controls the on-off of the switch circuit, and controls the switch circuit to selectively communicate with the multi-gear amplification module from the first primary amplifier and the second primary amplifier.

4. The current sampling device of claim 3, wherein, The switch circuit comprises a MOS tube, the first end of the MOS tube is connected with one end of the second resistor / the first resistor, the second end of the MOS tube is connected with the other end of the second resistor / the first resistor, and the control end of the MOS tube is connected with the controller.

5. The current sampling device of claim 3, wherein, The switch circuit comprises a first switch and a second switch, the first end of the first switch is connected with the first primary amplifier, the second end of the first switch is connected with the multi-gear amplification module, and the control end of the first switch is connected with the controller; The first end of the second switch is connected with the second primary amplifier, the second end of the second switch is connected with the multi-gear amplification module, and the control end of the second switch is connected with the controller.

6. The current sampling apparatus of claim 1, wherein, The resistance sampling module comprises a first resistor, a second resistor and a switch circuit; The first resistor and the second resistor are connected in parallel, and the parallel connection point of the first resistor and the second resistor is connected in series in the loop where the photovoltaic cell is located, and the multi-gear amplification module is connected with the parallel connection point of the first resistor and the second resistor; The resistance value of the first resistor is smaller than that of the second resistor, and the switch circuit is arranged at least on the branch of the first resistor, and the control end of the switch circuit is connected with the controller; The controller controls the on-off of the switch circuit.

7. The current sampling apparatus of claim 1, wherein, The multi-gear amplification module comprises an amplifier, a plurality of gain control resistors and a switch corresponding to each gain control resistor. The first end of the amplifier is the first end of the multi-gear amplification module, and is connected to the resistance sampling module; and the second end of the amplifier is the second end of the multi-gear amplification module, and is connected to the output module. A plurality of gain control resistors are connected in parallel to a gain control line of the amplifier; a first end of the switch is connected to one end of a corresponding gain control resistor; a second end of the switch is connected to a parallel junction of the plurality of gain control resistors; and a control end of the switch is the third end of the multi-gear amplification module, and is connected to the controller.

8. The current sampling apparatus of claim 1, wherein, The output module comprises an analog-to-digital converter, and the analog-to-digital converter is connected to the multi-gear amplification module.

9. The current sampling device of claim 8, wherein, The output module further comprises a single-ended-to-differential circuit, and the single-ended-to-differential circuit is connected between the multi-gear amplification module and the analog-to-digital converter.

10. An IV testing apparatus, characterized by, The current sampling device comprises any one of claims 1-9.

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