Photovoltaic module automatic on-off device and photovoltaic power generation system

Abstract

The application provides an automatic on-off device for a photovoltaic module, which is connected in series with the at least one photovoltaic module and comprises a voltage conversion module, a microcontroller, a switching device and a current acquisition module; the voltage conversion module is used to convert high voltage output by the photovoltaic module into low voltage; the microcontroller is powered; one end of the current acquisition module is connected with one end of the microcontroller to control the working of the microcontroller; the other end of the microcontroller is connected with the control end of the switching device to control the on-off of the switching device. The opening and closing of the photovoltaic power generation system are controlled based on the current in the main circuit through the automatic on-off device, so that the timely automatic opening and closing of the photovoltaic module are effectively ensured, and the safety of the photovoltaic power generation system is further ensured. In addition, the communication module is not needed in the automatic on-off device, so that the production cost is further reduced.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, specifically to an automatic on / off device for photovoltaic modules and a photovoltaic power generation system. Background Technology

[0002] Due to the renewable and clean nature of solar energy, photovoltaic grid-connected power generation technology has developed rapidly and is now widely used. However, while enjoying its convenience, we must also face its challenges. Specifically, there are safety concerns during the use of photovoltaic power generation. For example, when a photovoltaic power station system malfunctions and requires maintenance, or in the event of an earthquake, fire, or flood requiring rescue personnel, even if the grid power supply is shut off, the photovoltaic modules are still generating electricity, meaning there is still high-voltage electricity in the system that could endanger personal safety. In traditional string systems, the cumulative voltage of the entire string can typically reach 600V to 1000V. Loose connections, poor contact, damp wires, and broken insulation in photovoltaic modules can easily cause DC arcing, leading to fires.

[0003] Therefore, the 2017 NEC 690.12 photovoltaic system safety standard stipulates that when personnel enter the safety boundary, the distance to the photovoltaic array should be 305mm. Within 30 seconds of the activation of the fast shutdown device, the voltage outside the boundary should drop below 30V, and the voltage inside the boundary should drop below 80V. This necessitates providing a module-level fast shutdown device to disconnect the connections between modules, ensuring that the voltage at any two points in the system drops to within the safe range. To meet these requirements, the industry has introduced intelligent photovoltaic junction box solutions. These solutions involve adding a semiconductor switch to the photovoltaic junction box; in an emergency, a signal is sent to the semiconductor switch to shut off the module's output.

[0004] However, practical applications and theoretical analysis have revealed serious problems with the aforementioned semiconductor switch solution. Due to the characteristics of semiconductor switches, they will become conductive in high-temperature conditions such as fires, rendering the "off" function ineffective and failing to provide system safety. Furthermore, in existing technologies, to facilitate the switching on and off states of photovoltaic power generation systems, each photovoltaic module is typically equipped with a shutdown control system. This system is connected to a remote facility via wired or wireless communication, allowing maintenance personnel to remotely send commands to the shutdown control system to shut down the photovoltaic module's circuitry. However, both wired and wireless remote control methods require a large number of communication modules, connecting cables, and connectors, resulting in high costs.

[0005] The above-mentioned problems urgently need to be solved. Summary of the Invention

[0006] The present invention aims to overcome one of the above-mentioned shortcomings of the prior art and provides an automatic on / off device for photovoltaic modules and a photovoltaic power generation system.

[0007] The technical solution adopted by this invention to solve its technical problem is: an automatic switching device for photovoltaic modules, the device being connected in series with at least one photovoltaic module, including a voltage conversion module, a microcontroller, a switching device, and a current acquisition module; the voltage conversion module is connected to the photovoltaic module to convert the high voltage output by the photovoltaic module into a low voltage; the other end of the voltage conversion module is connected to one end of the microcontroller to supply power to the microcontroller; one end of the current acquisition module is connected to one end of the microcontroller to control the operation of the microcontroller; the other end of the microcontroller is connected to the control terminal of the switching device to control the switching on and off of the switching device.

[0008] Furthermore, the voltage conversion module is connected to the photovoltaic module to convert the high voltage output by the photovoltaic module into a low voltage, including: the voltage conversion module is connected in series with the photovoltaic module to convert the high voltage output by the photovoltaic module into a low voltage.

[0009] Furthermore, the other end of the voltage conversion module is connected to one end of the microcontroller to supply power to the microcontroller, including: when the voltage conversion module supplies power to the microcontroller, the microcontroller is in an on state; when the voltage conversion module does not supply power to the microcontroller, the microcontroller is in a off state; and / or when the microcontroller malfunctions, the microcontroller is in a off state.

[0010] Furthermore, one end of the current acquisition module is connected to one end of the microcontroller to control the operation of the microcontroller, including: the current acquisition module converts the main circuit current signal into a voltage signal and feeds it back to the controller to control the operation of the controller.

[0011] Furthermore, the current acquisition module converts the main circuit current signal into a voltage signal and feeds it back to the controller. Controlling the operation of the controller includes: when the microcontroller is in the on state and receives the voltage signal fed back by the current acquisition module, the microcontroller operates normally; when the microcontroller is in the off state, the microcontroller cannot operate normally.

[0012] Furthermore, the other end of the microcontroller is connected to the control terminal of the switching device to control the switching device's on / off state, including: the microcontroller controlling the switching device to turn on or off based on the control signal received from the current acquisition module; when the current acquisition module acquires a current signal, controlling the microcontroller to turn the switching device on; when the current acquisition module does not acquire a current signal, controlling the microcontroller to turn the switching device off.

[0013] Furthermore, the microcontroller controls the switching device to be turned on or off based on the control signal received from the current acquisition module, including: when the switching device is off, the photovoltaic module is not connected to the main circuit; when the switching device is on, the photovoltaic module is connected to the main circuit.

[0014] Furthermore, the device also includes a bypass diode module, one end of which is connected to the second electrode of the switching device, and the other end of which is connected to one end of the photovoltaic module.

[0015] Furthermore, the switching device includes one of a MOSFET, IGBT, thyristor, transistor, and relay.

[0016] The present invention also provides a photovoltaic power generation system, including one or more photovoltaic modules and a photovoltaic inverter module. The two ends of the photovoltaic modules are connected to the photovoltaic inverter module, or the two ends of the multiple photovoltaic modules connected in series are connected to the photovoltaic inverter module. The photovoltaic module includes photovoltaic components connected in series and an automatic switching device for the photovoltaic components. The photovoltaic inverter module is used to: generate a main circuit current input to the automatic switching device for the photovoltaic components when the photovoltaic inverter module starts working; the switching device is used to: receive the current signal and, based on the current signal, control the on / off state of the switching device to connect the photovoltaic components to the main circuit or disconnect the photovoltaic components.

[0017] The beneficial effects of this invention are as follows: By disclosing an automatic switching device for photovoltaic modules, the device is connected in series with at least one photovoltaic module and includes a voltage conversion module, a microcontroller, a switching device, and a current acquisition module. The voltage conversion module is connected to the photovoltaic module to convert the high voltage output by the photovoltaic module into a low voltage. The other end of the voltage conversion module is connected to one end of the microcontroller to supply power to the microcontroller. One end of the current acquisition module is connected to one end of the microcontroller to control the operation of the microcontroller. The other end of the microcontroller is connected to the control terminal of the switching device to control the switching on and off of the switching device. Based on the current in the main circuit controlling the opening and closing of the photovoltaic power generation system through the automatic switching device, the timely automatic opening and closing of the photovoltaic modules can be effectively guaranteed, further ensuring the safety of the photovoltaic power generation system. Furthermore, since the automatic switching device does not require a communication module, production costs are further reduced. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Figure 1 This is a circuit diagram of the automatic on / off device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a photovoltaic power generation system provided in an embodiment of the present invention.

[0020] Figure label: 1- Photovoltaic module; 2- Photovoltaic inverter module; 11- Photovoltaic modules; 12-Automatic on / off device for photovoltaic modules; 120-Voltage Conversion Module; 121 - Microcontroller; 122 - Switching devices; 124 - Current Acquisition Module; D-Bypass Diode. Detailed Implementation

[0021] Before discussing the exemplary embodiments in more detail, it should be noted that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe the operations as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but may also have additional steps not included in the figures. The process can correspond to a method, function, procedure, subroutine, subroutine, etc.

[0022] It should be understood that although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0023] The present invention will now be described in detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0024] To facilitate subsequent understanding, the working principle of a photovoltaic power generation system will be explained.

[0025] Photovoltaic (PV) modules convert sunlight into direct current (DC). This DC is then converted into alternating current (AC) by an inverter and transmitted to the power grid, ultimately enabling electricity consumption and grid connection. Specifically, a PV system consists of several PV modules connected in series. The current generated by each module is connected via cables to form a main circuit, which is then fed into the grid through an inverter. When the inverter is connected, there is current in the main circuit of the PV system. When the inverter is disconnected, the PV system is in an open state, and there is no current in the main circuit.

[0026] Example 1 Please see Figure 1 This invention presents a schematic diagram of an automatic on / off device for photovoltaic modules.

[0027] As an example, the photovoltaic module automatic switching device 12 is connected in series with the at least one photovoltaic module 11. The photovoltaic module automatic switching device 12 includes a voltage conversion module 120, a microcontroller 121, a switching device 122, and a current acquisition module 124.

[0028] As an example, the voltage conversion module 120 is connected to the photovoltaic module 11 to convert the high voltage output by the photovoltaic module into a low voltage.

[0029] Optionally, the voltage conversion module 120 is connected in series with the photovoltaic module 11 to convert the high voltage output by the photovoltaic module 11 into a low voltage. Since the voltage of the photovoltaic module 11 is generally between 40-60V, this high voltage is obviously unsuitable for device operation. If the device's operating voltage is 5V, the voltage conversion module 120 needs to convert the high voltage output by the photovoltaic module 11 into a low voltage suitable for powering the device, allowing it to operate normally. The voltage conversion module 120 is equipped with a step-down chip; a BX8206 DC-DC step-down chip can be used, with an input voltage range of 20-70V and an adjustable output voltage of 1.5-55V.

[0030] It should be noted that the selection of this particular model of step-down chip is only for reference here. Relevant technical personnel can select different models of step-down chips according to actual needs, or configure transformers in the voltage conversion module, etc. There are no restrictions here.

[0031] As an example, the other end of the voltage conversion module 120 is connected to one end of the microcontroller 121 to supply power to the microcontroller 121.

[0032] Optionally, when the voltage conversion module 120 supplies power to the microcontroller 121, the microcontroller 121 is in the ON state; when the voltage conversion module 120 does not supply power to the microcontroller 121, the microcontroller 121 is in the OFF state; and / or when the microcontroller 121 itself malfunctions, the microcontroller 121 is also in the OFF state.

[0033] Optionally, the microcontroller 121 is powered by the photovoltaic module 11. Since the voltage output by the photovoltaic module 11 is too high, a voltage conversion module 120 is provided between the photovoltaic module 11 and the microcontroller 121 to reduce the high voltage output by the photovoltaic module 11 to a low voltage that can be used by the microcontroller 121.

[0034] Optionally, the photovoltaic module 11 directly converts light energy into electrical energy through the photovoltaic effect, thus powering the microcontroller 121. When the photovoltaic module 11 is normally powering the microcontroller 121, the microcontroller 121 is in the "on" state. However, it should be noted that this "on" state is not the same as the "operating" state. When the photovoltaic module 11 malfunctions, such as when it is broken, it cannot power the microcontroller 121, meaning the microcontroller 121 is in the "off" state.

[0035] As an example, one end of the current acquisition module 124 is connected to one end of the microcontroller 121 to control the operation of the microcontroller 121.

[0036] Optionally, the current acquisition module converts the main circuit current signal into a voltage signal and feeds it back to the microcontroller to control the microcontroller to work; when the microcontroller is in the on state and receives the voltage signal fed back by the current acquisition module, the microcontroller works normally; when the microcontroller is in the off state, the microcontroller cannot work normally.

[0037] Optionally, the current acquisition module 124 is used to receive the current signal generated by the main circuit and convert the current signal into a voltage signal, which is then provided to the microcontroller 121.

[0038] As shown in the figure, OUT+ and OUT- can be the output terminals of the automatic on / off device 12 for photovoltaic modules, and can also be used as the input terminals for the main circuit current. That is, when the inverter in the photovoltaic power generation system is turned on, the photovoltaic power generation system is in normal working condition, and a current will be generated in the main circuit. The current acquisition module 214 will collect the current in the main circuit and convert it into a voltage signal, which will be sent to the microcontroller 121 to enable the microcontroller 121, which is in the on state, to work normally. However, if the microcontroller 121 is in the off state, the voltage control signal sent by the current acquisition module 124 cannot enable the microcontroller 121 to work, and the microcontroller 121 will remain in the off state, i.e., in a non-working state.

[0039] This method supplies power to the microcontroller 121 via the photovoltaic module 11, enabling the microcontroller 121 to be in an on or off state. The current acquisition module 124 then further controls the microcontroller 121 based on the current in the main circuit. Even when the microcontroller 121 is on, it is still in working condition. This allows the system to quickly identify which photovoltaic module 11 is damaged when it fails to work, such as when the photovoltaic module 11 is damaged. This enables relevant technicians to quickly perform subsequent repairs or replacements on the photovoltaic module, thereby further ensuring the safety and stability of the photovoltaic power generation system.

[0040] As an example, the other end of the microcontroller 121 is connected to the control terminal of the switching device 122 to control the on / off state of the switching device 122.

[0041] Optionally, the microcontroller 121 controls the switching device 122 to turn on or off based on the control signal received from the current acquisition module 124; when the current acquisition module 124 acquires a current signal, it controls the microcontroller 121 to turn on the switching device 122; when the current acquisition module 124 does not acquire a current signal, it controls the microcontroller 121 to turn off the switching device 122. When the switching device 122 is off, the photovoltaic module 11 is not connected to the main circuit; when the switching device 122 is on, the photovoltaic module 11 is connected to the main circuit.

[0042] Optionally, when there is current in the main circuit and the photovoltaic module 11 can power the microcontroller 121 to be in the on state, the current acquisition module 124 converts the acquired current signal in the main circuit into a voltage signal and sends it to the microcontroller 121. The microcontroller 121 controls the switching device 122 to be in the connected state, and the photovoltaic module 11 is connected to the main circuit at this time. When there is current in the main circuit, but the photovoltaic module 11 cannot power the microcontroller 121 to be in the off state, the current acquisition module 124 converts the acquired current signal in the main circuit into a voltage signal and sends it to the microcontroller 121. At this time, since the microcontroller 121 is in the off state, the microcontroller 121 cannot control the switching device 122 to be in the connected state, and the photovoltaic module 11 is not connected to the main circuit at this time. When there is no current in the main circuit, regardless of whether the photovoltaic module 11 can supply power to the microcontroller 121, the microcontroller 121 cannot receive the voltage signal sent by the current acquisition module 124, and therefore cannot control the switching device 122 to connect or disconnect. Thus, the photovoltaic module 11 is not connected to the main circuit at this time. The switching device 122 includes one of the following: MOSFET, IGBT, thyristor, transistor, and relay; no limitation is made here.

[0043] The method described above in this invention involves an automatic on / off device for photovoltaic modules periodically detecting the main circuit current of the photovoltaic power generation system. When the inverter is disconnected and there is no current in the main circuit, the automatic on / off device automatically commands the corresponding photovoltaic module to shut down its circuit, thus achieving automatic shutdown of the photovoltaic module. When the inverter is turned on and there is current in the main circuit, if the photovoltaic module is still in normal operating condition, the automatic on / off device automatically commands the corresponding photovoltaic module to connect its circuit, thus achieving automatic startup of the photovoltaic module.

[0044] As an example, the automatic switching device for photovoltaic modules also includes a bypass diode module (not shown in the figure), one end of which is connected to the second terminal of the switching device 122, and the other end of which is connected to one end of the photovoltaic module 11. Specifically, as Figure 1 As shown, the bypass diode module includes a diode D. The cathode of diode D is connected to the second terminal of the switching device 122, and the anode is connected to one end of the photovoltaic module 11. This bypass diode further protects the circuit.

[0045] Example 2 like Figure 2 The diagram shown is a schematic of a photovoltaic power generation system.

[0046] As an example, the system includes one or more photovoltaic modules 1 and photovoltaic inverter modules 2. The two ends of the photovoltaic modules 1 are connected to the photovoltaic inverter modules 2, or the two ends of the multiple photovoltaic modules 1 connected in series are connected to the photovoltaic inverter modules 2. The photovoltaic module 1 includes photovoltaic components 11 connected in series and a photovoltaic component automatic switching device 12. The photovoltaic inverter module 2 is used to generate a main circuit current input to the photovoltaic component automatic switching device 12 when the photovoltaic inverter module 3 starts working. The switching device 12 is used to receive the current signal and control the switching state of the switching device 12 according to the current signal, so as to connect the photovoltaic components 11 into the main circuit or disconnect the photovoltaic components 11.

[0047] Optionally, the photovoltaic module 1 includes n photovoltaic units 11 connected in series. Each photovoltaic unit 11 includes a photovoltaic module 11 and a photovoltaic module automatic shutdown device 12. The first and second ends of the photovoltaic module 11 are connected to the photovoltaic module automatic shutdown device 12. The photovoltaic module automatic shutdown device 12 can be connected to the corresponding previous photovoltaic module and the corresponding next photovoltaic module, or the photovoltaic inverter module 2 can be connected to the corresponding next photovoltaic module, where n ≥ 1. The photovoltaic inverter module 2 is equipped with a photovoltaic inverter.

[0048] As an example, the photovoltaic power generation system may also include a power grid. The photovoltaic module 1 converts light energy into electrical energy, wherein the current signal is direct current. The direct current is converted into alternating current by the photovoltaic inverter module 2, and then transmitted to the power grid via the photovoltaic inverter module 2.

[0049] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of this utility model. These should also be considered within the scope of protection of this utility model, and will not affect the effectiveness of the invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. An automatic on / off device for photovoltaic modules, the device being connected in series with the at least one photovoltaic module, characterized in that, It includes a voltage conversion module, a microcontroller, switching devices, and a current acquisition module; The voltage conversion module is connected to the photovoltaic module to convert the high voltage output by the photovoltaic module into a low voltage. The other end of the voltage conversion module is connected to one end of the microcontroller to supply power to the microcontroller, including: When the voltage conversion module supplies power to the microcontroller, the microcontroller is in the ON state; When the voltage conversion module does not supply power to the microcontroller, the microcontroller is in a powered-off state; and / or When the microcontroller malfunctions, the microcontroller is in a shut-down state; One end of the current acquisition module is connected to one end of the microcontroller to control the operation of the microcontroller, including: the current acquisition module converts the main circuit current signal into a voltage signal and feeds it back to the controller to control the operation of the microcontroller; Specifically, this includes: when the microcontroller is in the ON state, and when it receives the voltage signal fed back by the current acquisition module, the microcontroller operates normally; When the microcontroller is in the off state, the microcontroller cannot function properly; The other end of the microcontroller is connected to the control terminal of the switching device, and the microcontroller controls the switching device to turn on or off based on the control signal received from the current acquisition module. When the current acquisition module acquires a current signal, the microcontroller controls the switching device to turn on; When the current acquisition module fails to acquire a current signal, the microcontroller controls the switching device to disconnect. When the inverter in the photovoltaic power generation system is turned on, the photovoltaic power generation system is in normal working condition. At this time, current will be generated in the main circuit. The current acquisition module collects the current in the main circuit and converts it into a voltage signal and sends it to the microcontroller, so that the microcontroller in the turned-on state can work normally. If the microcontroller is in the turned-off state, the voltage control signal sent by the current acquisition module cannot make the microcontroller work. At this time, the microcontroller is still in the turned-off state, that is, in the non-working state.

2. The automatic on / off device for photovoltaic modules as described in claim 1, characterized in that, The voltage conversion module is connected to the photovoltaic module and is used to convert the high voltage output by the photovoltaic module into a low voltage, including: The voltage conversion module is connected in series with the photovoltaic module to convert the high voltage output by the photovoltaic module into a low voltage.

3. The automatic on / off device for photovoltaic modules as described in claim 1, characterized in that, The microcontroller controls the switching device to turn on or off based on the control signal received from the current acquisition module, including: When the switching device is disconnected, the photovoltaic module is not connected to the main circuit; When the switching device is connected, the photovoltaic module is connected to the main circuit.

4. The automatic on / off device for photovoltaic modules as described in claim 1, characterized in that, The device also includes a bypass diode module, one end of which is connected to the second electrode of the switching device, and the other end of which is connected to one end of the photovoltaic module.

5. The automatic on / off device for photovoltaic modules as described in claim 1, characterized in that, The switching device includes one of the following: MOSFET, IGBT, thyristor, transistor, and relay.

6. A photovoltaic power generation system, comprising one or more photovoltaic modules and a photovoltaic inverter module, wherein the two ends of the photovoltaic modules are connected to the photovoltaic inverter module, or the two ends of the plurality of photovoltaic modules connected in series are connected to the photovoltaic inverter module; The photovoltaic module includes photovoltaic modules connected in series and an automatic on / off device for the photovoltaic modules as described in claim 1; The photovoltaic inverter module is used to: when the photovoltaic inverter module starts working, the electricity generated by the photovoltaic modules connected in series in the power generation system is fed into the power grid; The shutdown device is used to: receive the current signal and control the on / off state of the shutdown device according to the current signal, so as to connect the photovoltaic module into the main circuit or disconnect the photovoltaic module.

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