Photovoltaic Cell Simulator

Abstract

The present invention provides a photovoltaic cell simulator, comprising a photocurrent simulation module and an open-circuit voltage simulation module, wherein the output end of the photocurrent simulation module is connected to an external load and the open-circuit voltage simulation module; the photocurrent simulation module is used to: generate a target current, and control the target current to match set current information, wherein the set current information is used to simulate the photocurrent of a target photovoltaic cell under corresponding target lighting conditions; the open-circuit voltage simulation module is used to: form a target voltage between the output end of the photocurrent simulation module and ground, wherein the target voltage when reaching a maximum value matches the set voltage information; the set voltage information is used to simulate the open-circuit voltage of the target photovoltaic cell under the target lighting conditions; wherein the target lighting conditions and the target photovoltaic cell are the lighting conditions and photovoltaic cells currently required to be simulated.

Description

Technical Field

[0001] The invention relates to the technical field of solar photovoltaic power generation, and in particular to a photovoltaic cell simulator. Background Art

[0002] In the field of photovoltaic power generation technology, solar photovoltaic cells are greatly affected by external environmental factors. Light conditions and ambient temperature will have an impact on them, and they are uncontrolled and difficult to control their working conditions. Therefore, in testing or R&D experiments, technicians usually use photovoltaic cell simulators to simulate solar photovoltaic cells, and adjust the working point by controlling the photovoltaic simulator or peripheral circuits to simulate the characteristics of solar photovoltaic cells.

[0003] In the prior art, there are mainly two types of photovoltaic cell simulators: analog and digital. An analog photovoltaic cell simulator is a device and environment that simulates sunlight. The working point can be adjusted by controlling the light source. However, the analog photovoltaic cell simulator is greatly affected by the simulated light source and temperature, and thus cannot accurately control the output power of the photovoltaic cell. Large errors can cause serious deviations in the open circuit voltage and maximum power point of the photovoltaic cell.

[0004] The digital photovoltaic cell simulator combines power electronics technology with digital signal DSP or single-chip microcomputer technology, based on various power electronics topologies, and simulates the characteristics of solar photovoltaic cells through multi-stage energy conversion according to the requirements of the system's own design parameters. However, the digital photovoltaic cell simulator is limited by the topological frequency of the control circuit, and the sampling, calculation and feedback control circuits require a certain control time. Its dynamic response capability is weak and cannot meet the requirements of high-speed application circuits or optimizers. Summary of the invention

[0005] The present invention provides a photovoltaic cell simulator to solve the problems in the prior art that the simulated light source and the ambient temperature are uncontrollable resulting in large errors and the dynamic response capability is weak due to the limitation of the control circuit topology frequency.

[0006] A photovoltaic cell simulator provided according to the present invention comprises a photocurrent simulation module and an open-circuit voltage simulation module, wherein the output end of the photocurrent simulation module is connected to an external load and the open-circuit voltage simulation module;

[0007] The photocurrent simulation module is used for:

[0008] Generate a target current, control the target current to match the set current information, and output the target current to the open circuit voltage simulation module and the external load, wherein the set current information is used to simulate the photocurrent of the target photovoltaic cell under the corresponding target illumination condition;

[0009] The open circuit voltage simulation module is used for:

[0010] forming a target voltage between the output terminal of the photocurrent simulation module and ground, wherein the target voltage when reaching a maximum value matches the set voltage information, wherein the set voltage information is used to simulate the open circuit voltage of the target photovoltaic cell under the target illumination condition;

[0011] The target illumination condition and the target photovoltaic cell are illumination conditions and photovoltaic cells that are currently required to be simulated.

[0012] Optionally, the photocurrent simulation module includes a DC voltage source and a variable resistance unit;

[0013] The positive electrode of the DC voltage source is connected to the first end of the variable resistance unit, and the negative electrode of the DC voltage source is directly or indirectly grounded; the second end of the variable resistance unit is connected to the external load and the open circuit voltage simulation module;

[0014] The resistance value of the variable resistance unit matches the set current information.

[0015] Optionally, the variable resistance unit includes an electronic load.

[0016] Optionally, the open circuit voltage simulation module includes a diode array; the anode of the diode array is connected to the output end of the photocurrent simulation module.

[0017] Optionally, the diode array includes at least one diode series group, and the diode series group includes at least one diode; the number of diodes connected in series in the diode series group matches the set voltage information.

[0018] Optionally, the open circuit voltage simulation module also includes a diode array control component; the diode array control component is electrically connected to the diode array; the diode array control component is used to: control the number of diodes connected in series in the diode array according to the set voltage information.

[0019] Optionally, the diode array control component is further used to: adjust the number of diode series groups that are turned on in parallel in the diode array.

[0020] Optionally, the diode array is a Schottky diode array.

[0021] Optionally, the open circuit voltage simulation module also includes a temperature environment device, which is used to generate a target environment with a target temperature. The diode array is arranged in the target environment, and the number of diodes connected in series in the diode series group, the target temperature and the set voltage information are matched.

[0022] Optionally, the open circuit voltage simulation module further includes a photovoltaic panel;

[0023] The input end of the photovoltaic panel is connected to the output end of the photocurrent simulation module.

[0024] The photovoltaic cell simulator provided by the present invention can simulate different lighting conditions by utilizing different set current information of the photocurrent simulation module and different set voltage information of the open-circuit voltage simulation module. Therefore, it avoids the errors caused by the uncontrollable simulated light source in the prior art and the weak dynamic response capability caused by the frequency limitation of the control circuit topology, effectively improves the accuracy of the simulation, and can fully meet the use requirements of the photovoltaic simulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention 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 invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 is the equivalent circuit diagram of a photovoltaic cell;

[0027] Figure 2 It is the working output characteristic curve of photovoltaic cells;

[0028] Figure 3 This is a typical diode characteristic curve;

[0029] Figure 4 Schematic diagram of a photovoltaic cell simulator in one embodiment of the present invention Figure 1 ;

[0030] Figure 5 Schematic diagram of a photovoltaic cell simulator in one embodiment of the present invention Figure 2 ;

[0031] Figure 6 Schematic diagram of a photovoltaic cell simulator in one embodiment of the present invention Figure 3 ;

[0032] Figure 7 FIG. 1 is a circuit diagram of a diode array in one embodiment of the present invention. Figure 1 ;

[0033] Figure 8 Schematic diagram of a photovoltaic cell simulator in one embodiment of the present invention Figure 4 .

[0034] Description of Reference Numerals

[0035] 1- Photocurrent simulation module;

[0036] 11- DC voltage source;

[0037] 12- variable resistance unit;

[0038] 2-Open circuit voltage simulation module;

[0039] 21- diode array control device;

[0040] 3- External load;

[0041] load-electronic load;

[0042] D-diode array;

[0043] D1 - diode;

[0044] Dn-diode;

[0045] K1-diode switch;

[0046] K2-diode series group switch;

[0047] Iph - target current. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0050] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0051] Furthermore, the term “connected” in the specification and claims of the present invention refers to an electrical connection, which may include a direct connection or an indirect connection.

[0052] The basic design principle of the present invention is described below in conjunction with the background technology:

[0053] like Figure 1 From the equivalent circuit of the photovoltaic cell shown in the figure, we can see that, ignoring the influence of the resistor Rs and the resistor Rsh, its core components are the constant current source and the diode. Several important parameters include: the photovoltaic cell photocurrent I ph (Equivalent to the short-circuit current I SC ), dark current I D , open circuit voltage U oc Its working output characteristic curve is as follows: Figure 2 shown.

[0054] like Figure 1 In the photovoltaic cell equivalent circuit shown in the figure, without considering the influence of the resistance Rs, the open circuit voltage U oc Equal to the dark current I corresponding to the diode D The forward conduction voltage drop under the photovoltaic cell is ph A constant current source can be used instead. In the present invention, a DC voltage source and an electronic load are directly used to realize the constant current source function. The advantage is that the current size can be directly controlled by the electronic load to adjust the photovoltaic cell photocurrent I ph size.

[0055] Figure 3 is a typical diode characteristic curve, its current I F With voltage V F The relationship between the dark current I D and open circuit voltage U oc Therefore, the current I through the diode can be adjusted F The size is used to simulate the dark current I D , by connecting diodes in series and in parallel to simulate the open circuit voltage U oc .

[0056] Based on the above design principles, the present invention provides a photovoltaic cell simulator. Figure 4 The photovoltaic cell simulator includes a photocurrent simulation module 1 and an open-circuit voltage simulation module 2, wherein the output end of the photocurrent simulation module 1 is connected to an external load 3 and the open-circuit voltage simulation module 2;

[0057] The photocurrent simulation module 1 is used to: generate a target current Iph, and control the target current Iph to match the set current information, wherein the set current information is used to simulate the photocurrent of the target photovoltaic cell under the corresponding target illumination conditions;

[0058] The open circuit voltage simulation module 2 is used for:

[0059] A target voltage is formed between the output terminal of the photocurrent simulation module 1 and the ground, wherein the target voltage when reaching a maximum value matches the set voltage information, wherein the set voltage information is used to simulate the open circuit voltage of the target photovoltaic cell under the target illumination condition;

[0060] Wherein, the target illumination condition and the target photovoltaic cell are the illumination condition and photovoltaic cell currently required to be simulated;

[0061] In an exemplary working process, the photocurrent simulation module 1 outputs a target current Iph matching the set current information, wherein the set current information can simulate the preset illumination conditions that need to be simulated at present, and when other parameters remain unchanged, different set current information represents different illumination conditions;

[0062] When the current flowing through the external load 3 is zero, the target voltage formed by the open circuit voltage simulation module 2 between the output end of the photocurrent simulation module 1 and the ground reaches a maximum value, and the maximum voltage value matches the set voltage information. The target voltage at this time is the open circuit voltage of the target photovoltaic cell under the target lighting conditions; different set voltage information represents different lighting conditions.

[0063] As the current flowing through the external load 3 increases, the voltage across the open circuit voltage simulation module 2 will decrease. When the voltage across the open circuit voltage simulation module 2 is close to zero, the current flowing through the photocurrent simulation module 1 and the external load 3 (that is, the target current Iph generated by the photocurrent module 1) is the photocurrent of the target photovoltaic cell under the target lighting conditions.

[0064] It can be seen that the present invention can utilize different set current information of the photocurrent simulation module 1 and different set voltage information of the open-circuit voltage simulation module 2 to simulate different lighting conditions. Therefore, it avoids the errors caused by the uncontrollable simulated light source and temperature in the prior art, and the weak dynamic response capability caused by the frequency limitation of the control circuit topology, effectively improves the accuracy of the simulation, and can fully meet the use requirements of the photovoltaic simulator.

[0065] In one implementation, please refer to Figure 5 , the photocurrent simulation module 1 includes a DC voltage source 11 and a variable resistance unit 12;

[0066] The positive pole of the DC voltage source 11 is connected to the first end of the variable resistance unit 12; the negative pole of the DC voltage source 11 is directly or indirectly grounded; the second end of the variable resistance unit 12 is connected to the external load 3 and the open circuit voltage simulation module 2; the resistance value of the variable resistance unit 12 matches the set current information.

[0067] The resistance value of the variable resistor unit 12 matches the set current information, which can be understood as: changing the set current information can be achieved by changing the resistance value of the variable resistor unit 12 , and different set current information corresponds to different resistance values ​​of the variable resistor unit 12 .

[0068] In one example, the variable resistance unit 12 includes a plurality of resistors connected in series and / or in parallel, and the resistance value of the variable resistance unit 12 can be changed by changing the number of resistors connected in series and / or in parallel. For example, one or more resistors can be connected in parallel with a resistance switch, and the number of resistors connected in series and / or in parallel can be changed by controlling the on and off of the resistance switch, thereby changing the resistance value of the variable resistance unit 12.

[0069] In a further example, the resistance switch can be connected to a resistance switch control device, the resistance switch control device is connected to a current detection component, and the current detection component is connected in series to the photocurrent simulation module 1. The current detection component is used to detect the target current Iph of the photocurrent simulation module 1 and feed the detection result back to the resistance switch control component, and the resistance switch control component is used to control the on and off of the resistance switch according to the set current information and the detection result, thereby controlling the target current Iph of the variable resistance unit 12 to match the set current information.

[0070] In other examples, as long as the resistance value of the resistor is changed to change the target current Iph of the photocurrent simulation module 1 so that the target current Iph of the photocurrent simulation module 1 matches the set current information, it does not deviate from the scope of the embodiments of the present invention.

[0071] In one embodiment, the variable resistance unit 12 includes an electronic load, and a current value can be input by typing, knob input or signal input to match the set current information, thereby making the target current Iph of the photocurrent simulation module 1 match the set current information.

[0072] In one implementation, please refer to Figure 6 , the open circuit voltage simulation module 2 includes a diode array D;

[0073] The anode D of the diode array is connected to the output end of the photocurrent simulation module 1 .

[0074] In one embodiment, Figure 7For example, the diode array D includes at least one diode series group (for example, a diode series group formed by connecting diodes D1 in series, and a diode series group formed by connecting diodes Dn in series), the diode series group includes at least one diode, and the number of diodes connected in series in the diode series group matches the set voltage information.

[0075] The number of diodes connected in series in the diode series group matches the set voltage information, which can be understood as: changing the set voltage information can be achieved by changing the number of diodes connected in series in the diode series group, and different set voltage information corresponds to different numbers of diodes connected in series.

[0076] In addition, by connecting multiple diode series groups in parallel, it is possible to prevent the diode from overheating and causing changes in characteristics. At the same time, the parallel connection of diode series groups can also increase the output power of the target photovoltaic cell under target lighting conditions.

[0077] In one implementation, please refer to Figure 7 The open circuit voltage simulation module 2 also includes a diode array control component, which is electrically connected to the diode array D; the diode array control component is used to: control the number of diodes connected in series in the diode array D according to the set voltage information.

[0078] In one embodiment, the diode array control component is further used to: adjust the number of diode series groups that are turned on in parallel in the diode array D.

[0079] For an example, please refer to Figure 7 The diode array control component includes a diode array control device 21, a diode switch K1 and a diode series group switch K2, wherein each diode may be connected in parallel with a diode switch K1, or multiple diodes may be connected in parallel with a diode switch K1; each diode series group may be connected in series with a diode series group switch K2, or multiple diode series groups may be connected in series with a diode series group switch K2.

[0080] The diode array control device 21 controls the number of diodes connected in series and the number of diode series groups connected in parallel in the diode array D by controlling the on and off of the diode switch K1 and the diode series group switch K2, thereby controlling the voltage at both ends of the open circuit voltage module 2 to reach the maximum value to match the set voltage information.

[0081] In other examples, the diode array D may also be replaced as a whole, and different diode arrays D correspond to different set voltage information.

[0082] In one implementation, the diode array D is a Schottky diode array.

[0083] In one embodiment, the open circuit voltage simulation module 2 also includes a temperature environment device, which is used to generate a target environment with a target temperature. The diode array D is set in the target environment, and the number of diodes turned on in the diode series group, the target temperature and the set voltage information are matched.

[0084] The matching of the number of diodes conducting in the diode series group, the target temperature and the set voltage information can be understood as: changing the number of diodes conducting in the diode series group and changing the target temperature can change the set voltage information. When the number of diodes conducting in the diode series group remains unchanged, different target temperatures correspond to different set voltage information, that is, different target temperatures represent different lighting conditions.

[0085] In one example, the temperature control device is used to control the diode array D to be at a certain target temperature so that the characteristics of the diode array D are not affected by the ambient temperature, ensuring that the current open circuit voltage of the photovoltaic cell is only related to the number of diodes connected in series in the diode array D and the target current Iph of the photocurrent simulation module 1, thereby minimizing the error; in other examples, the temperature control device can also control the target environment to change the target temperature while other parameters remain unchanged, thereby changing the open circuit voltage of the photovoltaic cell to simulate changes in lighting conditions.

[0086] In addition, the temperature control device, diode array control device and other control devices can also be integrated into the same control device. During the simulation process, the control device can not only control the hardware in the simulator, but also obtain various signals detected during the simulation process (such as relevant electrical signals of the simulator itself, or relevant electrical signals of external loads, and various signals obtained by detecting the environment, devices, and equipment, etc.)

[0087] Please refer to Figure 8 The following describes three working modes of an embodiment of the photovoltaic cell simulator:

[0088] Open circuit mode: When the current IL of the external load 3 is zero, the current passing through the diode array D is equal to the target current Iph of the photocurrent simulation module 1, that is, Id=Iph. At this time, the voltage across the diode array D (that is, the target voltage formed between the output end of the photocurrent simulation module and the ground) is the largest. At this time, the voltage can simulate the open circuit voltage Uoc of the photovoltaic cell, and the current Id through the diode array simulates the dark current of the photovoltaic cell.

[0089] Load mode: When the current of the external load 3 is IL, the current Id through the diode array = Iph-IL, and the voltage across the diode array will drop. As the external load current IL increases, the current through the diode array D will also gradually decrease. At this time, the voltage drop across the diode array D decreases as the external load increases, and it works in the load mode;

[0090] Short-circuit current mode: As the current IL of the external load 3 increases, the current passing through the diode array is very small. At this time, as the external load current IL continues to increase, the voltage across the diode will drop sharply, that is, it will enter the short-circuit current mode. At this time, the target current Iph flowing through the photocurrent simulation module 1 can simulate the photocurrent of the photovoltaic cell.

[0091] Among them, the maximum operating voltage of the DC voltage source 11 in the circuit must be greater than the maximum value of the set voltage information that meets the simulation needs, and needs to be higher. The current capacity of the DC voltage source 11 must be greater than the maximum value of the set current information that meets the simulation needs.

[0092] In one implementation, the open circuit voltage simulation module 2 further includes a photovoltaic panel; an input end of the photovoltaic panel is connected to an output end of the photocurrent simulation module 1 .

[0093] In one example, the photovoltaic panel may include one photovoltaic panel unit, and in other examples, the photovoltaic panel may include a plurality of photovoltaic panel units.

[0094] If the photovoltaic panel includes a plurality of photovoltaic panel units, the number of photovoltaic panel units that are turned on in the photovoltaic panel matches the set voltage information;

[0095] Among them, the number of photovoltaic panel units turned on in the photovoltaic panel matches the set voltage information, which can be understood as: changing the set voltage information can be achieved by changing the number of photovoltaic panel units turned on in the photovoltaic panel, and different set voltage information corresponds to different numbers of photovoltaic panel units turned on.

[0096] In one example, the number of photovoltaic panel units in the photovoltaic panel that are turned on can be controlled by a photovoltaic panel control component. In other examples, manual intervention can also be performed, such as manually turning on or off the photovoltaic panel units to change the number of photovoltaic panel units in the photovoltaic panel.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A photovoltaic cell simulator, characterized in that: It includes a photocurrent simulation module and an open-circuit voltage simulation module, wherein the output end of the photocurrent simulation module is connected to an external load and the open-circuit voltage simulation module; The photocurrent simulation module is used for: Generate a target current, control the target current to match the set current information and output the target current to the open circuit voltage simulation module and the external load, wherein the set current information is used to simulate the photocurrent of the target photovoltaic cell under the corresponding target illumination condition; Wherein, the photocurrent simulation module includes a DC voltage source and a variable resistance unit; The positive electrode of the DC voltage source is connected to the first end of the variable resistance unit, and the negative electrode of the DC voltage source is directly or indirectly grounded; the second end of the variable resistance unit is connected to the external load and the open circuit voltage simulation module; The resistance value of the variable resistance unit matches the set current information; The open circuit voltage simulation module is used for: A target voltage is formed between the output terminal of the photocurrent simulation module and the ground, wherein the target voltage when reaching a maximum value matches the set voltage information; the set voltage information is used to simulate the open circuit voltage of the target photovoltaic cell under the target illumination condition; Wherein, the target illumination condition and the target photovoltaic cell are the illumination condition and photovoltaic cell currently required to be simulated; Wherein, the open circuit voltage simulation module includes a diode array, a diode array control component and a temperature environment device; the diode array control component is electrically connected to the diode array; The anode of the diode array is connected to the output end of the photocurrent simulation module; The diode array includes at least one diode series group, and the diode series group includes at least one diode; The number of diodes connected in series in the diode series group matches the set voltage information; The diode array control assembly is used for: According to the set voltage information, controlling the number of diodes connected in series in the diode array; Adjusting the number of diode series groups connected in parallel in the diode array; The temperature environment device is used to generate a target environment with a target temperature. The diode array is arranged in the target environment. The number of diodes connected in series in the diode series group, the target temperature and the set voltage information are matched.

2. The photovoltaic cell simulator according to claim 1, characterized in that: The variable resistance unit includes an electronic load.

3. The photovoltaic cell simulator according to claim 1, characterized in that: The diode array is a Schottky diode array.

4. The photovoltaic cell simulator according to any one of claims 1 to 2, characterized in that: The open circuit voltage simulation module includes a photovoltaic panel; The input end of the photovoltaic panel is connected to the output end of the photocurrent simulation module.

Images