IV test system and method of solar cell

Abstract

The invention provides an IV test system for a solar cell, and the system comprises a light source assembly, an electronic load device, a data processing device, and a to-be-tested cell. The electronic load device comprises a voltage and current test module, a main control module and an MCU module, and the voltage and current test module comprises a voltage acquisition channel and at least one current acquisition channel; the main control module comprises a control unit, a voltage acquisition unit and at least one group of current acquisition unit and current scanning unit, the voltage acquisition channel is electrically connected with the voltage acquisition unit and the battery piece to be tested, and the current acquisition channel is electrically connected with the battery piece to be tested, one group of current acquisition unit and one group of current scanning unit. The control unit is electrically connected with the voltage acquisition unit, the current acquisition unit, the current scanning unit and the MCU module, and the MCU module is electrically connected with the power supply assembly and the data processing device. Current scanning and current and voltage acquisition are synchronously realized, and the accuracy of data acquisition is improved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic testing, and in particular to an IV testing system and method for a solar cell. Background Art

[0002] Photovoltaic is the abbreviation of solar photovoltaic power generation system. It is a new type of power generation system that uses the photovoltaic effect of solar cell semiconductor materials to directly convert solar radiation energy into electrical energy. In recent years, the photovoltaic industry has developed very rapidly. The demand for solar cells has increased, and the technology of cells has been improved, which has also put forward higher requirements for cell testing equipment. Efficient and accurate detection of the electrical performance of solar cells can improve the efficiency of cell production and provide guidance for the improvement of cell production technology. Solar cell IV test refers to the use of solar cell IV test system to simulate sunlight, irradiate the cell to be tested, detect the IV characteristics of the cell through the test device, and generate an IV curve.

[0003] In the existing solar cell IV test system, the scanning and collection of the cell current are separate and have no synchronization relationship. Usually, the current data is collected at a certain moment after the battery is scanned. At this time, it is impossible to determine whether the battery output has entered a stable state, resulting in some of the collected data being invalid data, leading to inaccurate final test results. Summary of the invention

[0004] The technical problem solved by the present invention is how to improve the accuracy of current acquisition data of a solar cell, and provides an IV test system and method for a solar cell.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] An IV test system for a solar cell comprises: a light source assembly, an electronic load device, a data processing device, and a cell to be tested;

[0007] The electronic load device includes a voltage and current test module, a main control module and an MCU module. The voltage and current test module includes a voltage acquisition channel and at least one current acquisition channel; the main control module includes a control unit, a voltage acquisition unit and at least one group of current acquisition units and current scanning units. The voltage acquisition channel is electrically connected to the voltage acquisition unit and the battery cell to be tested, the current acquisition channel is electrically connected to the battery cell to be tested and a group of current acquisition units and a current scanning unit. The control unit is electrically connected to the voltage acquisition unit, the current acquisition unit, the current scanning unit and the MCU module respectively, and the MCU module is electrically connected to the power supply component and the data processing device.

[0008] Preferably, the control unit includes a memory unit, a control register, a data acquisition timing unit and a clock generator; the data acquisition timing unit is electrically connected to the memory unit, the control register and the clock generator respectively; the memory unit is electrically connected to the control register and the MCU module; the data acquisition timing unit is electrically connected to the voltage acquisition unit, the current acquisition unit and the current scanning unit.

[0009] Preferably, the current collection channel includes a dark current collection channel, and the dark current collection channel is electrically connected to a group of current collection units and a current scanning unit.

[0010] Further preferably, the current acquisition channel includes a first current acquisition channel and a second current acquisition channel, the first current acquisition channel is used to measure a large current, and the second current acquisition channel is used to measure a small current.

[0011] Preferably, the light source assembly includes an LED module, a collimating lens, and a light forming system, and the light forming system includes an eyepiece, an optical integrator, and an objective lens;

[0012] The collimating lens is used to collimate the light emitted by the LED module;

[0013] In the light-forming system, the eyepiece converges the collimated light onto the optical integrator, and the optical integrator projects the output light through the objective lens.

[0014] Preferably, the electronic load device comprises a signal switching module, and the signal switching module is electrically connected to the voltage acquisition channel and the current acquisition channel.

[0015] Preferably, the MCU module is also connected to a temperature acquisition module and a light intensity acquisition module.

[0016] A method for IV testing of a solar cell, comprising:

[0017] The data acquisition timing unit obtains the control parameters in the control register;

[0018] The data acquisition timing unit controls the current scanning unit to perform current scanning according to the control parameters, controls the current acquisition unit to perform current acquisition, and controls the voltage acquisition unit to perform voltage acquisition;

[0019] The data acquisition timing unit writes the collected voltage and current data into the memory unit;

[0020] The MCU module obtains the voltage and current data stored in the memory unit and transmits the data to the data processing device.

[0021] Preferably, the data acquisition timing unit controls the current scanning unit to perform current scanning according to the control parameters, and at the same time, controls the current acquisition unit to perform current acquisition specifically including:

[0022] The data acquisition timing unit starts the current scanning timing in the current scanning unit;

[0023] The current scanning sequence drives the current acquisition channel to perform current scanning, wherein the point interval and step size of the current scanning are determined by the parameters of the control register.

[0024] Preferably, while the current is being scanned, the current acquisition unit drives the current acquisition channel to acquire current data.

[0025] Compared with the prior art, the present invention has the following beneficial effects: the electronic load device in the IV test system of the solar cell includes a voltage and current test module, a main control module and an MCU module, the voltage and current test module includes a voltage acquisition channel and at least one current acquisition channel; the main control module includes a control unit, a voltage acquisition unit and at least one group of current acquisition units and a current scanning unit, the voltage acquisition channel is electrically connected to the voltage acquisition unit and the cell to be tested, the current acquisition channel is electrically connected to the cell to be tested and a group of current acquisition units and a current scanning unit, the control unit is electrically connected to the voltage acquisition unit, the current acquisition unit, the current scanning unit and the MCU module respectively, and the MCU module is electrically connected to the power supply component and the data processing device. Through the internal logic of the main control module of FPGA technology, synchronous current scanning and current and voltage acquisition are realized under the drive of the same clock, that is, the logical relationship is one-to-one, and the data collected by the current and voltage at a certain moment is the result of the current scanning drive at the same moment. The current scanning and current and voltage acquisition are realized synchronously, which improves the accuracy of data acquisition. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic block diagram of an IV testing system for a solar cell according to an embodiment of the present invention;

[0028] Figure 2 A schematic block diagram of an IV testing system for a solar cell according to another embodiment of the present invention;

[0029] Figure 3 FIG. 4 is a flow chart of an IV testing method for a solar cell according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0031] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0032] In the description of the present invention, the meaning of "plurality" is more than two. If there is a description of "first" or "second", it is only for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0033] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0034] The core of the present invention is to provide an IV test system and method for solar cells for high-efficiency cells and perovskite cells, thereby realizing current scanning and current and voltage collection simultaneously, and improving the accuracy of data collection. Compared with traditional test systems, the present invention can cover all cells in the photovoltaic industry.

[0035] Reference Figure 1 , an embodiment of the present invention provides an IV test system for a solar cell, comprising: a light source assembly 100, an electronic load device 200, a data processing device 300, and a cell to be tested 400;

[0036] The electronic load device 200 includes a voltage and current test module 210, a main control module 220 and an MCU module 230. The voltage and current test module 210 includes a voltage acquisition channel 211 and at least one current acquisition channel 212; the main control module 220 includes a control unit 224, a voltage acquisition unit 221 and at least one group of current acquisition units 222 and a current scanning unit 223. The voltage acquisition channel 211 is electrically connected to the voltage acquisition unit 221 and the battery cell 400 to be tested, and the current acquisition channel 212 is electrically connected to the battery cell 400 to be tested and a group of current acquisition units 222 and a current scanning unit 223. The control unit 224 is electrically connected to the voltage acquisition unit 221, the current acquisition unit 222, the current scanning unit 223 and the MCU module 230 respectively, and the MCU module 230 is electrically connected to the power supply assembly 100 and the data processing device 300.

[0037] In a specific embodiment, the light source assembly 100 includes an LED solar simulator, and the LED solar simulator includes a plurality of LED lamp beads, and the plurality of LED lamp beads are arranged in a matrix in a certain order to fit the standard sunlight. The LED matrix is ​​internally divided into several sub-matrix blocks, and the LED wavelengths in each sub-matrix block cover the entire spectrum, that is, the entire LED matrix is ​​composed of a plurality of full-spectrum LED sub-matrices, which is beneficial to the uniformity of irradiation. The light source assembly can also be a xenon lamp. The battery cell 400 to be tested is located below the light source assembly 100, and the light source assembly 100 obtains simulated sunlight with uniform distribution and good light intensity stability. The light source assembly 100 is also connected to a power supply, and a 220V voltage is obtained through the power supply. A water cooler is provided inside the light source assembly 100 for cooling the light source assembly 100.

[0038] The MCU module 230 in the electronic load device 200 is electrically connected to the light source assembly 100 through the CAN bus to realize the control of the light source assembly 100. The electronic load device 200 is connected to the data processing device through a wired or wireless network. The data processing device is the host computer, including a PC. The test software on the PC can send commands and parameters, receive test data; pre-process the test data, calculate various parameters of the battery cell; display the calculation results in the form of graphics and data; save the calculation results and original data to the database for later reference. The overall working principle of the electronic load device 200 is: the electronic load device 200 is connected to the battery cell 400 to be tested, as the load of the battery cell 400 to be tested. The test process controls the load resistance from infinity (open circuit) to 0 (short circuit) through the program. During this change process, the current acquisition channel 212 and the voltage acquisition channel 211 collect the changes in the current and voltage output of the battery cell, thereby obtaining the IV data of the battery output, and then calculating the characteristic indicators of the battery cell from the IV data. This process mainly involves two parts. One part is the process of adjusting the resistance change, that is, current scanning. As the resistance changes, the current changes with the resistance, and the changing current is scanned. The other part is the data acquisition process.

[0039] The MCU module 230 acquires the collected data and writes it into the control unit to adjust the test process and parameters. The MCU module 230 exchanges data and commands with the host computer test software through a wired or wireless network.

[0040] In the electronic load in the prior art, the operations of the above two parts are independent and have no correlation. During the test process, scanning is implemented separately and acquisition is implemented separately. As the power generation efficiency of the battery cell becomes higher and higher, the capacitance effect of the battery cell itself becomes more and more obvious. For a certain current scanning point (the point where the resistance changes), if the battery cell does not reach a stable output due to the capacitance effect, it will be collected, and the collected data will be inaccurate. In the prior art, the test process is controlled by MCU software. Due to the control rhythm of the MCU itself, it is impossible to achieve precise synchronization of scanning and acquisition, and scanning and acquisition can only work independently. Compared with the prior art, the present invention realizes scanning and acquisition in one chip by using FPGA technology, that is, the main control module in the present invention. In the entire test process, scanning and acquisition are realized by hardware, which can be precisely synchronized, that is, for scanning a certain point, through delay setting, until the battery reaches a stable output, accurate data can be collected.

[0041] The usual way to deal with the above-mentioned cell capacitance effect is to extend the test time, which requires that the irradiation time of the light source should also be increased. For xenon lamps, it has a great impact on the lifespan, but for LEDs, there is no problem of affecting the lifespan. Due to the different capacitance effects of different batteries, a relatively long scanning interval is set, and stable output can usually be achieved for different cells before collection. The electronic load in the prior art can be accurately measured in this way, but its entire measurement cycle will become longer. Under ideal conditions, that is, it can be achieved under laboratory conditions, but for high-speed testing of production lines, it is obviously not possible to achieve a test beat of 4,000 pieces per hour. However, the present invention arbitrarily adjusts the test interval and test step length through hardware. The test step length is the degree of change of the scanning current, that is, the size of the resistance change during each scan. The minimum test interval and test step length for different cells under the condition of achieving accurate measurement are found to shorten the test time as much as possible, thereby matching the demand for high-speed testing on the production line, which meets the two-way demand of the increasingly advanced development of solar cell technology and high-speed detection of production lines, ensuring both data acquisition accuracy and data acquisition speed.

[0042] In a specific embodiment, the control unit 224 includes a memory unit 2241, a control register 2242, a data acquisition timing unit 2243 and a clock generator 2244; the data acquisition timing unit 2243 is electrically connected to the memory unit 2241, the control register 2242 and the clock generator 2244 respectively; the memory unit 2241 is electrically connected to the control register 2242 and the MCU module 230; the data acquisition timing unit 2243 is electrically connected to the voltage acquisition unit 221, the current acquisition unit 222 and the current scanning unit 223.

[0043] The data acquisition timing unit 2243 writes the collected voltage and current data into the memory unit 2241. After the data acquisition is completed, the MCU module 230 reads the data in the memory unit 2241 and transmits it to the host computer. The data acquisition timing unit 2243 obtains the test parameters by reading the control register 2242 to adjust the test process. The data acquisition timing unit 2243 drives the current acquisition channel 212 through the current scanning drive logic in the current scanning unit to control the entire current scanning process. The voltage acquisition channel 211 and the current acquisition channel 212 include A / D, and the data acquisition timing unit 2243 controls the A / D through the acquisition timing in the voltage acquisition unit 221 and the current acquisition unit 222 to realize data acquisition. The current acquisition channel includes D / A, and the data acquisition timing unit 2243 current scanning unit 223 current scanning timing controls the D / A to realize current scanning. The A / D or D / A therein adopts 16 bits to improve the test accuracy.

[0044] In a specific embodiment, the current acquisition channel 212 includes a dark current acquisition channel 2123, and the dark current acquisition channel 2123 is electrically connected to a group of current acquisition units 2223 and a current scanning unit 2233. The electronic load device 200 is divided into two test modes, one is an IV test mode, and the other is a dark current test mode. At this time, the voltage and current test module 210 includes at least one current acquisition channel 211 and a dark current acquisition channel 2123.

[0045] In a specific embodiment, the current acquisition channel 212 includes a first current acquisition channel 2121 and a second current acquisition channel 2122, wherein the first current acquisition channel 2121 is used to measure a large current, and the second current acquisition channel 2122 is used to measure a small current. In this embodiment, there are two current acquisition channels 212, namely the first current acquisition channel 2121 and the second current acquisition channel 2122, which are respectively used to collect large currents and small currents, so that current data collection is more accurate. In other words, the current acquisition channel can be one or more. When there are multiple current acquisition channels, each acquisition channel is respectively connected to a group of current acquisition units 222 and current scanning units 223. For example, the dark current acquisition channel 2123 is electrically connected to the current acquisition unit 2223 and the current scanning unit 2233; the first current acquisition channel 2121 is electrically connected to the current acquisition unit 2221 and the current scanning unit 2231; the second current acquisition channel 2122 is electrically connected to the current acquisition unit 2222 and the current scanning unit 2232, and each group of current acquisition units and current scanning units is electrically connected to the data acquisition timing unit 2243. That is, the electronic load device 200 is internally equipped with a plurality of current scanning timing logics and current acquisition timing logics, which have the same internal functions and are used to drive external D / A or A / D with different channels and functions.

[0046] In a specific embodiment, the light source assembly 100 includes an LED module, a collimating lens, and a light forming system, wherein the light forming system includes an eyepiece, an optical integrator, and an objective lens;

[0047] The collimating lens is used to collimate the light emitted by the LED module;

[0048] In the light forming system, the eyepiece converges the collimated light onto the optical integrator, and the optical integrator projects the output light through the objective lens. The light emitted by the LED module can be processed by the collimating lens and the light forming system to improve the uniformity of irradiation.

[0049] In a specific embodiment, the electronic load device 200 includes a signal switching module 240, and the signal switching module 240 is electrically connected to the voltage acquisition channel 211 and the current acquisition channel 212. When multiple channels are used to acquire current, such as Figure 2As shown, the first current collection channel 2121, the second current collection channel 2122, and the dark current collection channel 2123 are electrically connected to the signal switching module 240 respectively, and the signal switching module 240 is electrically connected to the battery cell 400 to be tested to achieve switching of different current collection channels.

[0050] In a specific embodiment, the MCU module 230 is also connected to a temperature acquisition module and a light intensity acquisition module. The MCU module 230 is responsible for collecting temperature and light intensity data, and packages the collected temperature and light intensity data together with the collected test current and voltage data and sends them to the host computer.

[0051] In summary, the advantage of using FPGA technology in the present invention is that compared with the traditional electronic load that cannot be modified, the use of FPGA technology can modify or optimize the design to realize the test of different battery cells. This is because the FPGA pins of the same series are compatible, their internal capacity can be large or small, and there is no upper limit to the functions that can be realized.

[0052] like Figure 3 As shown, the present invention provides an IV testing method for a solar cell, comprising:

[0053] S1. The data acquisition timing unit obtains the control parameters in the control register;

[0054] S2. The data acquisition timing unit controls the current scanning unit to perform current scanning according to the control parameters, controls the current acquisition unit to perform current acquisition, and controls the voltage acquisition unit to perform voltage acquisition;

[0055] S3. The data acquisition timing unit writes the collected voltage and current data into the memory unit;

[0056] S4. The MCU module obtains the voltage and current data stored in the memory unit and transmits it to the data processing device.

[0057] In a specific embodiment, the data acquisition timing unit controls the current scanning unit to perform current scanning according to the control parameter, and at the same time, controls the current acquisition unit to perform current acquisition, specifically including:

[0058] The data acquisition timing unit starts the current scanning timing in the current scanning unit;

[0059] The current scanning sequence drives the current acquisition channel to perform current scanning, wherein the point interval and step size of the current scanning are determined by the parameters of the control register.

[0060] The data acquisition timing unit starts the current scanning timing in the current scanning unit to control the external adjustable constant current source, thereby realizing the current scanning function. The direct interval and step size of each current scanning point are determined by the parameters of the control register, realizing fine control of the current scanning. The register for controlling the interval and step size in the control register is 16 bits, and the clock of this part of the circuit controlled by the main control module is 1MHz, realizing that the interval of each scanning point can be as small as 1us and as large as 64ms, which can cover various batteries. The interval of the current scanning is set according to the characteristics of the battery, which can ensure that each test point is data collected after the battery reaches a stable output at the current moment, so each test data is valid. Compared with the prior art, the present invention realizes scanning and collection in one chip by using FPGA technology, that is, the main control module in the present invention. In the entire test process, scanning and collection are realized by hardware, which can be accurately synchronized, that is, for scanning a certain point, by delay setting, when the battery reaches a stable output, accurate data can be collected. The delay setting mentioned here is the above-mentioned 1us to 64ms arbitrary setting to adapt to different battery slices.

[0061] In a specific embodiment, while the current is being scanned, the current acquisition unit drives the current acquisition channel to acquire current data.

[0062] Data acquisition timing logic and data acquisition control logic are both software controllable, and the system has high flexible control capabilities. For various solar cells, the output is voltage and current, and the hardware parts of voltage and current acquisition are basically the same. This solution can realize various acquisition sequence control and acquisition timing control to cover the test requirements of various batteries.

[0063] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0064] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. An IV test system for solar cells, characterized in that: include: Light source components, electronic load devices, data processing devices, and cells to be tested; The electronic load device comprises a voltage and current test module, a main control module and an MCU module, wherein the voltage and current test module comprises a voltage acquisition channel and at least one current acquisition channel; The main control module includes a control unit, a voltage acquisition unit and at least one group of current acquisition units and current scanning units. The voltage acquisition channel is electrically connected to the voltage acquisition unit and the battery cell to be tested. The current acquisition channel is electrically connected to the battery cell to be tested and a group of current acquisition units and current scanning units. The control unit is electrically connected to the voltage acquisition unit, the current acquisition unit, the current scanning unit and the MCU module respectively. The MCU module is electrically connected to the power supply component and the data processing device.

2. The IV test system for solar cells according to claim 1, characterized in that: The control unit includes a memory unit, a control register, a data acquisition timing unit and a clock generator; the data acquisition timing unit is electrically connected to the memory unit, the control register and the clock generator respectively; the memory unit is electrically connected to the control register and the MCU module; the data acquisition timing unit is electrically connected to the voltage acquisition unit, the current acquisition unit and the current scanning unit.

3. The IV test system for solar cells according to claim 2, characterized in that: The current collection channel includes a dark current collection channel, and the dark current collection channel is electrically connected to a group of current collection units and a current scanning unit.

4. The IV test system for solar cells according to claim 2, characterized in that: The current acquisition channel includes a first current acquisition channel and a second current acquisition channel, the first current acquisition channel is used to measure a large current, and the second current acquisition channel is used to measure a small current.

5. The IV test system for solar cells according to claim 1, characterized in that: The light source assembly includes an LED module, a collimating lens, and a light forming system, and the light forming system includes an eyepiece, an optical integrator, and an objective lens; The collimating lens is used to collimate the light emitted by the LED module; In the light forming system, the eyepiece converges the collimated light onto the optical integrator, and the optical integrator projects the output light through the objective lens.

6. The IV test system for solar cells according to claim 1, characterized in that: The electronic load device comprises a signal switching module, and the signal switching module is electrically connected to a current acquisition channel and a battery cell to be tested.

7. The IV test system for solar cells according to claim 1, characterized in that: The MCU module is also connected to a temperature acquisition module and a light intensity acquisition module.

8. A method for IV testing of a solar cell, characterized in that: include: The data acquisition timing unit obtains the control parameters in the control register; The data acquisition timing unit controls the current scanning unit to perform current scanning according to the control parameters, controls the current acquisition unit to perform current acquisition, and controls the voltage acquisition unit to perform voltage acquisition; The data acquisition timing unit writes the collected voltage and current data into the memory unit; The MCU module obtains the voltage and current data stored in the memory unit and transmits the data to the data processing device.

9. The IV test system for solar cells according to claim 8, characterized in that: The data acquisition timing unit controls the current scanning unit to perform current scanning according to the control parameters, and at the same time, controls the current acquisition unit to perform current acquisition specifically including: The data acquisition timing unit starts the current scanning timing in the current scanning unit; The current scanning sequence drives the current acquisition channel to perform current scanning, wherein the point interval and step length of the current scanning are determined by the parameters of the control register.

10. The IV testing system for solar cells according to claim 9, characterized in that: While the current is being scanned, the current acquisition unit drives the current acquisition channel to acquire current data.

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