Photovoltaic turn-off circuit and photovoltaic system

Abstract

The invention provides a photovoltaic turn-off circuit and a photovoltaic system, the photovoltaic turn-off circuit is used for performing turn-off control on a photovoltaic module, the circuit comprises a photovoltaic turn-off module, an undervoltage locking module, a first resistor and a first switching tube, and when the input voltage of the photovoltaic module is smaller than a first threshold voltage, the undervoltage locking module is turned off. And the under-voltage locking module outputs a second driving voltage to the control end of the first switching tube to conduct the first switching tube. The resistance value of the first resistor represents the ratio of the first threshold voltage to the first working current, and the first working current represents the lowest working current of the photovoltaic turn-off module, so that the output voltage of the photovoltaic module is pulled down to be below the first threshold voltage by the first resistor; therefore, the photovoltaic turn-off module is ensured not to be restarted repeatedly due to weak light in the morning and evening. Meanwhile, the under-voltage locking module also outputs a second enable signal to the photovoltaic turn-off module when the input voltage of the photovoltaic module is smaller than the first threshold voltage, so as to stop the work of the photovoltaic turn-off module, thereby greatly reducing the power consumption of the photovoltaic turn-off module.

Description

Technical Field

[0001] The present invention relates to the field of electronic circuits, and in particular to a photovoltaic shutdown circuit and a photovoltaic system. Background Art

[0002] According to NEC690.12, for the safety of firefighters and on-site maintenance personnel in emergency situations, photovoltaic systems in buildings need to be equipped with photovoltaic circuit breakers. Currently, more and more countries and regions are gradually establishing similar industry standards.

[0003] While meeting safety shutdown regulations, module-level monitoring is becoming increasingly necessary. Module-level monitoring enables real-time alarms and monitoring, helping operations personnel manage risks promptly through alarm information and prevent further losses from escalating risks. Monitoring can accurately locate anomalies and analyze the causes of problems, effectively improving operation and maintenance efficiency and reducing costs. However, in photovoltaic systems with module-level monitoring, low light levels in the morning and evening can cause the corresponding photovoltaic shutdown circuits to repeatedly restart, significantly reducing system reliability.

[0004] However, the existing technology cannot reduce the power consumption of the circuit when solving the problem of repeated restart of the photovoltaic shutdown circuit caused by weak light in the morning and evening. Summary of the Invention

[0005] The present invention provides a photovoltaic shutdown circuit and a photovoltaic system, which solve the problem of repeated restarting of the photovoltaic shutdown circuit during weak light conditions in the morning and evening on the basis of low power consumption.

[0006] To solve the above technical problems, a first aspect of the present invention provides a photovoltaic shutdown circuit for controlling the shutdown of a photovoltaic module, the photovoltaic shutdown circuit comprising: A photovoltaic shutdown module, the photovoltaic shutdown module is used to: According to the first enable signal, the device operates normally to control the on / off of the DC path of the photovoltaic assembly; stopping operation and shutting down a DC path of the photovoltaic assembly according to a second enable signal; an undervoltage lockout module, configured to compare the input voltage of the photovoltaic module with a first threshold voltage; if the input voltage is greater than the first threshold voltage, the undervoltage lockout module outputs a first driving voltage and the first enable signal; if the input voltage is less than the first threshold voltage, the undervoltage lockout module outputs a second driving voltage and the second enable signal; the first threshold voltage is used to represent the starting voltage of the photovoltaic shutdown module; a first resistor, wherein a first end of the first resistor is coupled to the positive output terminal of the photovoltaic assembly, and a resistance value of the first resistor is used to represent a ratio between the first threshold voltage and a first operating current, and the first operating current is used to represent a minimum operating current of the photovoltaic shutdown module; a first switch tube, wherein a first end of the first switch tube is coupled to the second end of the first resistor, a second end of the first switch tube is coupled to the negative output end of the photovoltaic component, a control end of the first switch tube is coupled to the first output end of the undervoltage lockout module, and the first switch tube is turned off according to the first driving voltage and turned on according to the second driving voltage.

[0007] Optionally, the photovoltaic shutdown module includes an auxiliary power supply unit, a data control unit, a second switch tube, a drive unit and an output capacitor; The auxiliary power supply unit is used to perform voltage conversion on the input voltage of the photovoltaic assembly and output a supply voltage, and the supply voltage is used to power various modules and units in the photovoltaic shutdown circuit. The first threshold voltage is used to represent the starting voltage of the auxiliary power supply unit, and the first operating current is used to represent the minimum operating current of the auxiliary power supply unit; The data control unit is configured to output a first drive control signal when simultaneously receiving an external input opening signal and a second opening signal; The driving unit is configured to output a third driving voltage according to the first driving control signal; A first terminal of the second switch tube is coupled to the positive output terminal of the photovoltaic assembly, a second terminal of the second switch tube is coupled to the first terminal of the output capacitor, a control terminal of the second switch tube is coupled to the output terminal of the driving unit, and the second switch tube is turned on according to the third driving voltage; The second terminal of the output capacitor is coupled to the negative output terminal of the photovoltaic component.

[0008] Optionally, the photovoltaic shutdown circuit further includes: a second resistor and a third switch tube; A first end of the second resistor is coupled to the positive output terminal of the photovoltaic module, and a second end of the second resistor is coupled to the first end of the third switch. The resistance of the second resistor is used to represent the ratio between a second threshold voltage and a second operating current. The second threshold voltage is used to represent the ratio between a starting voltage of an inverter in a photovoltaic system and the number of photovoltaic shutdown circuits in series in the photovoltaic system. The second operating current is used to represent the minimum operating current of the inverter. The second end of the third switch tube is coupled to the negative output end of the photovoltaic assembly, and the control end of the third switch tube is coupled to the second output end of the undervoltage lockout module; The undervoltage lockout module is further configured to: When the data control unit receives the external input turn-on signal, the data control unit outputs a fourth driving voltage to the control terminal of the third switch tube to turn on the third switch tube; After the third switch tube is turned on, if the input voltage of the photovoltaic component is greater than the second threshold voltage, a fifth driving voltage is output to the control end of the third switch tube to turn off the third switch tube and output the second turn-on signal to the data control unit.

[0009] Optionally, the data control module is further configured to output a second driving control signal to the driving unit when the second activation signal is not received; The driving unit is further configured to output a sixth driving voltage to the control terminal of the second switch tube according to the second driving control signal, so as to turn off the second switch tube.

[0010] Optionally, the first switch tube, the second switch tube and the third switch tube all include at least NMOS tubes.

[0011] Optionally, the driving unit includes a charge pump and a driving subunit; The charge pump is used to boost the supply voltage and output the boosted voltage to the driver sub-unit. The driver sub-unit outputs a second high drive voltage and a second floating voltage based on the boosted voltage and the first drive control signal. The second high drive voltage acts on the control terminal of the second switch tube, and the second floating voltage acts on the second terminal of the second switch tube. The second high drive voltage is greater than the second floating drive voltage, and the difference between the second high drive voltage and the second floating voltage is equal to the third drive voltage.

[0012] Optionally, the photovoltaic shutdown module further includes a signal receiving module and a signal transformer; The signal transformer is used to receive a third activation signal transmitted by the system; The signal receiving module is used to perform first signal processing on the third activation signal respectively, and output the external input activation signal.

[0013] Optionally, the photovoltaic shutdown module further includes a temperature detection module, an analog-to-digital conversion module and a signal sending module; The temperature detection module is used to convert the temperature in the circuit into a first digital signal and output it to the data control module; The analog-to-digital conversion module is used to convert the sampled voltage of the output voltage of the photovoltaic module into a second digital signal and output it to the data control module; The data control module is used to read the signal according to the external input data, and output the first digital signal and the second digital signal to the signal sending module respectively. The signal sending module is used to perform second signal processing on the first digital signal and output a third digital signal, and to perform second signal processing on the second digital signal and output a fourth digital signal.

[0014] A second aspect of the present invention provides a photovoltaic system, comprising: a system controller configured to output a third activation signal according to an externally input control signal; A plurality of photovoltaic assemblies and a plurality of photovoltaic shutdown circuits provided by the first aspect of the present invention, wherein the plurality of photovoltaic assemblies and the plurality of photovoltaic shutdown circuits correspond one to one, and the positive output terminal of each photovoltaic assembly is coupled to the positive input terminal of the corresponding photovoltaic shutdown circuit, and the negative output terminal of each photovoltaic assembly is coupled to the negative output terminal of the photovoltaic shutdown circuit. The plurality of photovoltaic shutdown circuits are connected in series, and the positive output terminal of the first photovoltaic shutdown circuit is coupled to the output terminal of the system controller, and the negative output terminal of the photovoltaic shutdown circuit is coupled to the positive output terminal of an adjacent photovoltaic shutdown circuit. An inverter, wherein a negative input terminal of the inverter is coupled to a negative output terminal of the last photovoltaic shutdown circuit, and a positive input terminal of the inverter is coupled to the system controller.

[0015] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: The photovoltaic shutdown circuit provided by the present invention comprises a first end of a first resistor coupled to the positive output terminal of the photovoltaic module, a first end of a first switching transistor coupled to the second end of the first resistor, and a second end of the first switching transistor coupled to the negative output terminal of the photovoltaic module. When the input voltage of the photovoltaic module falls below a first threshold voltage due to weak light conditions in the morning or evening, the undervoltage lockout module outputs a second drive voltage to the control terminal of the second switching transistor to turn on the second switching transistor. Since the resistance of the first resistor represents the ratio between the first threshold voltage and the first operating current, and the first operating current represents the minimum operating current of the photovoltaic shutdown module, after turning on the first switching transistor, the output voltage of the photovoltaic module is pulled down by the first resistor to below the first threshold voltage until the output current of the photovoltaic module reaches the minimum operating current of the photovoltaic shutdown module. This ensures that the photovoltaic shutdown module does not repeatedly restart due to weak light conditions in the morning or evening. Furthermore, the undervoltage lockout module outputs a second enable signal to the photovoltaic shutdown module when the input voltage of the photovoltaic module falls below the first threshold voltage to stop the photovoltaic shutdown module, thereby significantly reducing the power consumption of the photovoltaic shutdown module. In summary, the technical solution of the present invention not only ensures that the photovoltaic shutdown module will not be repeatedly restarted due to weak light in the morning and evening, but also greatly reduces the power consumption of the photovoltaic shutdown module during weak light in the morning and evening.

[0016] Furthermore, the technical solution of the present invention further comprises a second resistor and a third switch. The first end of the second resistor is coupled to the positive output terminal of the photovoltaic module, the second end of the second resistor is coupled to the first end of the third switch, and the second end of the third switch is coupled to the negative output terminal of the photovoltaic module. When the data control unit receives the external input activation signal, the undervoltage lockout module outputs a fourth drive voltage to the control terminal of the third switch to turn on the third switch. Since the resistance of the second resistor represents the ratio between the second threshold voltage and the second operating current (the second threshold voltage represents the ratio between the startup voltage of the inverter in the photovoltaic system and the number of photovoltaic shutdown circuits in series), and the second operating current represents the minimum operating current of the inverter, the second switch is turned off until the output current of the photovoltaic module exceeds the second operating current, so that the input voltage of the photovoltaic module exceeds the second threshold voltage, thereby preventing the inverter in the system from repeatedly restarting. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The circuit structure of the photovoltaic shutdown circuit provided by the embodiment of the present invention is shown in FIG. Figure 1 ; Figure 2The circuit structure of the photovoltaic shutdown circuit provided by the embodiment of the present invention is shown in FIG. Figure 2 ; Figure 3 The circuit structure of the photovoltaic shutdown circuit provided by the embodiment of the present invention is shown in FIG. Figure 3 ; Figure 4 1 is a schematic diagram of a circuit structure of a photovoltaic shutdown circuit provided by another embodiment of the present invention; Figure 5 2 is a schematic diagram of the system structure of a photovoltaic system provided by another embodiment of the present invention. DETAILED DESCRIPTION

[0018] As described in the background art, the existing technology cannot reduce the power consumption of the circuit when solving the problem of repeated restart of the photovoltaic shutdown circuit caused by weak light in the morning and evening.

[0019] In view of this, the technical solution of the present invention provides a new photovoltaic shutdown circuit to solve the problem of repeated restarting of the photovoltaic shutdown circuit due to weak light in the morning and evening on the basis of low power consumption.

[0020] To make the above-mentioned objectives, features, and beneficial effects of the present invention more readily apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. It should be understood that the described embodiments are only some, and not all, of the embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. The terms "first," "second," "third," "fourth," and so on (if any) in the specification and claims of the present invention and the accompanying drawings are used to distinguish similar items and are not necessarily used to describe a specific order or precedence. It should be understood that such terms are interchangeable where appropriate, such that the embodiments of the present invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "including," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product, or apparatus.

[0021] Figure 1 The circuit structure of the photovoltaic shutdown circuit provided by the embodiment of the present invention is shown in FIG. Figure 1 .

[0022] Please refer to Figure 1The photovoltaic shutdown circuit provided by the embodiment of the present invention is used to perform shutdown control on the photovoltaic module 1. The shutdown control can be understood as turning on or off the DC path of the photovoltaic module 1.

[0023] The photovoltaic shutdown circuit includes: a photovoltaic shutdown module 10, an undervoltage lockout module 20, a first resistor R1 and a first switch tube Q1.

[0024] The photovoltaic shutdown module 10 is configured to operate normally and control the conduction of the DC path of the photovoltaic assembly 1 according to the first enable signal EN1 and to stop operating and shut down the DC path of the photovoltaic assembly 1 according to the second enable signal EN2.

[0025] The undervoltage lockout module 20 is configured to compare the input voltage of the photovoltaic module 1 with a first threshold voltage. If the input voltage is greater than the first threshold voltage, the undervoltage lockout module 20 outputs a first driving voltage V1 and a first enable signal EN1. If the input voltage is less than the first threshold voltage, the undervoltage lockout module 20 outputs a second driving voltage V2 and a second enable signal EN2. The first threshold voltage is used to represent the starting voltage of the photovoltaic shutdown module 10.

[0026] The first end of the first resistor R1 is coupled to the positive output terminal VOUT1+ of the photovoltaic component 1. The resistance of the first resistor R1 is used to represent the ratio between the first threshold voltage and the first operating current. The first operating current is used to represent the minimum operating current of the photovoltaic shutdown module 10.

[0027] The first end of the first switch tube Q1 is coupled to the second end of the first resistor R1, the second end of the first switch tube Q1 is coupled to the negative output terminal VOUT1- of the photovoltaic component 1, and the control end of the first switch tube Q1 is coupled to the first output terminal of the undervoltage lockout module 20. The first switch tube Q1 is turned off according to the first driving voltage V1 and is turned on according to the second driving voltage V2.

[0028] Specifically, the first switch transistor Q1 includes a conventional NMOS transistor, an N-type silicon carbide MOS transistor, an N-type gallium nitride HEMT transistor, an N-type IGBT transistor, etc., and can be adaptively selected based on the voltage resistance, power requirements, switching speed requirements, and cost requirements of the actual application scenario, and is not limited here. For example, if the first switch transistor Q1 is a conventional NMOS transistor, the first end of the first switch transistor Q1 is the drain of the NMOS transistor, the second end of the first switch transistor Q1 is the source of the NMOS transistor, and the control end of the first switch transistor Q1 is the gate of the NMOS transistor. For ease of explanation, the first switch transistor Q1 is hereinafter referred to as an NMOS transistor.

[0029] When the light is weak in the morning and evening, the output power of the photovoltaic module 1 will gradually decrease and cannot meet the normal operation of the photovoltaic shutdown module 10. Specifically, in order to maintain its own minimum operating current, the photovoltaic shutdown module 10 continuously lowers the output voltage of the photovoltaic module 1, causing the output voltage of the photovoltaic module 1 to be lower than the starting voltage of the photovoltaic shutdown module 10. At this time, the undervoltage lockout module 20 outputs the second driving voltage V2 to the control terminal of the first switch tube Q1 to turn on the first switch tube Q1. Since the resistance value of the first resistor R1 is used to represent the ratio between the first threshold voltage and the first operating current, and the first operating current is used to represent the minimum operating current of the photovoltaic shutdown module 10, after turning on the first switch tube Q1, the output voltage of the photovoltaic module 1 will be pulled down by the first resistor R1 because the output current of the photovoltaic module 1 does not meet the minimum operating current of the photovoltaic shutdown module 10. It can be understood that the product of the output current of the photovoltaic module 1 and the resistance value of the first resistor R1 equals the output voltage of the photovoltaic module 1. If the output current of the photovoltaic module 1 is lower than the minimum operating current of the photovoltaic shutdown module 10, the output voltage of the photovoltaic module 1 will fall below the first threshold voltage, causing the photovoltaic shutdown module 10 to stop operating. At the same time, the undervoltage lockout module 20 will also output a second enable signal EN2 when the output voltage of the photovoltaic module 1 falls below the first threshold voltage to ensure that the photovoltaic shutdown module 10 stops operating. This ensures that the photovoltaic shutdown module 10 will not repeatedly restart due to low light conditions in the morning and evening (i.e., the output voltage of the photovoltaic module 1 is lower than the first threshold voltage). It also significantly reduces the power consumption of the photovoltaic shutdown module 10 during low light conditions in the morning and evening.

[0030] When the output power of the photovoltaic assembly 1 meets the working requirements of the photovoltaic shutdown module 10, that is, the output voltage of the photovoltaic assembly 1 is greater than or equal to the first threshold voltage, and the output current of the photovoltaic assembly 1 is greater than or equal to the first working current, the undervoltage lockout module 20 outputs a first driving voltage V1 to the first switch tube Q1 and outputs a first enable signal EN1 to the photovoltaic shutdown module 10 to turn off the first switch tube Q1 and enable the photovoltaic shutdown module 10. Therefore, when the output power of the photovoltaic assembly 1 meets the working requirements of the photovoltaic shutdown module 10, the photovoltaic shutdown module 10 operates normally, that is, the photovoltaic shutdown module 10 normally controls the conduction of the DC path of the photovoltaic assembly 1.

[0031] Figure 2 The circuit structure of the photovoltaic shutdown circuit provided by the embodiment of the present invention is shown in FIG. Figure 2 .

[0032] Please refer to Figure 2 In one embodiment, the photovoltaic shutdown module 10 includes an auxiliary power supply unit 11, a data control unit 12, a second switch tube Q2, a driving unit 13 and an output capacitor Cout.

[0033] The auxiliary power supply unit 11 is used to perform voltage conversion on the input voltage of the photovoltaic assembly 1 and output a power supply voltage VDD. The power supply voltage VDD is used to power various modules and units in the photovoltaic shutdown circuit.

[0034] Specifically, the starting voltage of the photovoltaic shutdown module 10 can be understood as the starting voltage of the auxiliary power supply unit 11 , and the minimum operating current of the photovoltaic shutdown module 10 can be understood as the minimum operating current of the auxiliary power supply unit 11 .

[0035] The supply voltage VDD can at least power the data control unit 12, the drive unit 13, and the undervoltage lockout module 20. In actual applications, the photovoltaic shutdown module 10 may also include other functional modules, so the supply voltage VDD can also power other functional modules, which is not limited here.

[0036] The data control unit 12 is configured to output a first driving control signal v1 when simultaneously receiving an external input opening signal von1 and a second opening signal von2.

[0037] The driving unit 13 is configured to output a third driving voltage V3 in response to the first driving control signal v1. A first terminal of the second switching transistor Q2 is coupled to the positive output terminal VOUT1+ of the photovoltaic assembly 1. A second terminal of the second switching transistor Q2 is coupled to the first terminal of the output capacitor Cout. A control terminal of the second switching transistor Q2 is coupled to the output terminal of the driving unit 13. The second switching transistor Q2 is turned on in response to the third driving voltage V3. A second terminal of the output capacitor Cout is coupled to the negative output terminal of the photovoltaic assembly 1.

[0038] Specifically, the driving unit 13 includes a charge pump 131 and a driving sub-unit 132. The charge pump 131 is configured to boost the input voltage of the photovoltaic module and output the boosted voltage to the driving sub-unit 132. The driving sub-unit 132 outputs a second high-drive voltage VH2 and a second floating voltage Vref based on the boosted voltage and the first driving control signal v1. The second high-drive voltage VH2 is applied to the control terminal of the second switching transistor Q2, and the second floating voltage Vref is applied to the second terminal of the second switching transistor Q2. The second high-drive voltage VH2 is greater than the second floating voltage Vref, and the difference between the second high-drive voltage VH2 and the second floating voltage Vref is equal to the third driving voltage V3. It can be understood that the driver subunit 132 is a floating drive circuit that drives the second switch transistor Q2 on the high-voltage side. The second floating voltage Vref floats with the bus voltage at the second end of the second switch transistor Q2, ensuring that the difference between the second high-voltage drive voltage VH2 and the second floating voltage Vref is fixed to a third drive voltage V3, thereby driving the second switch transistor Q2. Of course, in addition to the above-mentioned embodiments, the driver subunit 132 may also adopt other conventional solutions for driving high-voltage side power transistors in the art, such as a bootstrap drive circuit, which is not limited here.

[0039] Specifically, the structure and type of the second switch tube Q2 are the same as those of the first switch tube Q1, and are not described in detail here.

[0040] Figure 3 The circuit structure of the photovoltaic shutdown circuit provided by the embodiment of the present invention is shown in FIG. Figure 3 .

[0041] Please refer to Figure 3 In one embodiment, the photovoltaic shutdown module 10 further includes a temperature detection unit 14 , an analog-to-digital conversion unit 15 , a signal sending module 17 , a signal receiving unit 16 and a signal transformer 18 .

[0042] The temperature detection unit 14 is used to convert the temperature in the circuit into a first digital signal and output the first digital signal to the data control unit 12 .

[0043] The analog-to-digital conversion unit 15 is used to convert the sampled voltage of the output voltage of the photovoltaic assembly 1 into a second digital signal and output the second digital signal to the data control unit 12 .

[0044] The data control unit 12 is further configured to output the first digital signal and the second digital signal to the signal sending module 17 according to an externally input data reading signal.

[0045] The signal sending module 17 is configured to perform second signal processing on the first digital signal and output a third digital signal, and to perform second signal processing on the second digital signal and output a fourth digital signal.

[0046] Specifically, the signal transmission module 17 includes a modulation unit, a low-order drive unit, a high-order drive unit, and a selection switch. The modulation unit is used to modulate the input digital signal into a control signal; the high-order drive unit is used to generate a 143.75kHz sine wave; and the low-order drive unit is used to generate a 131.25kHz sine wave. Under the control of the control signal, the selection switch periodically outputs a 143.75kHz sine wave or a 131.25kHz sine wave, that is, outputs the third and fourth digital signals. For example, if the digital signal is equivalent to 1010, the selection switch will output a 143.75kHz sine wave lasting 5.12ms, followed by a 131.25kHz sine wave lasting 5.12ms, followed by a 143.75kHz sine wave lasting 5.12ms, and finally a 131.25kHz sine wave lasting 5.12ms, based on the control signal output by the modulation unit.

[0047] The signal transformer 18 is used to receive the third activation signal von3 transmitted by the system.

[0048] Specifically, the signal transformer 18 is used to receive the third activation signal von3 transmitted by the system. This can be understood as enabling signal exchange between the low-voltage controller and the high-voltage photovoltaic assembly 1 in the system. Furthermore, the signal transformer 18 also achieves electrical isolation between the low-voltage controller and the high-voltage photovoltaic assembly 1. The signal transformer 18 can include any of a pulse transformer, an isolation drive transformer, a planar transformer, or a current transformer, without limitation herein.

[0049] The signal receiving unit 16 is configured to perform first signal processing on the third enable signal von3 and output the external input enable signal von1 .

[0050] Specifically, the signal receiving unit 16 includes a filtering subunit 161, an amplifying subunit 162, and a signal demodulating subunit 163, so the first signal processing includes signal filtering, signal amplification, and signal demodulation in sequence. It can be understood that the third activation signal von3 is filtered by the filtering subunit 161, amplified by the amplifying subunit 162, and demodulated by the signal demodulating subunit 163 in sequence to obtain the external input activation signal von1. Furthermore, the filtering subunit 161 includes a conventional filtering circuit, such as an RC filtering circuit, which will not be described in detail here. The amplifying subunit 162 includes a common emitter amplifier circuit, an operational amplifier circuit, etc., which will not be described in detail here. The structure of the signal demodulating subunit 163 changes according to the modulation mode of the input signal, and setting the corresponding demodulation structure according to the different demodulation modes of the input signal is a conventional technical means in this field and will not be described in detail here.

[0051] In summary, the photovoltaic shutdown circuit provided in this embodiment not only ensures that the photovoltaic shutdown module will not be repeatedly restarted due to weak light in the morning and evening, but also greatly reduces the power consumption of the photovoltaic shutdown module during weak light in the morning and evening.

[0052] The above embodiment has solved the problem of the photovoltaic shutdown module 10 repeatedly restarting in the morning and evening due to its own power consumption. However, in addition to the photovoltaic shutdown module 10 repeatedly restarting in the morning and evening due to low light conditions, the inverter in the photovoltaic system also has the same problem. The principle is as follows: During low light conditions in the morning and evening, when the total power provided by several series-connected photovoltaic modules 1 is insufficient for the inverter to operate normally, that is, the total module power provided by the series-connected photovoltaic modules 1 is less than the inverter's minimum operating power, the inverter will lower the input voltage of the several photovoltaic modules 1 to maintain its minimum operating current until the sum of the output voltages of the several photovoltaic modules 1 falls below the inverter's starting voltage, causing the inverter to stop operating. After the inverter stops operating, the output voltage of the photovoltaic modules 1 increases because there is no inverter current supply, causing the sum of the output voltages of the several photovoltaic modules 1 to once again exceed the inverter's starting voltage, restarting the inverter. However, since the total module power provided by the several photovoltaic modules 1 has not increased, the inverter will quickly shut down again, causing it to repeatedly restart.

[0053] Figure 4 1 is a schematic diagram of the circuit structure of a photovoltaic shutdown circuit provided by another embodiment of the present invention.

[0054] Please refer to Figure 4 In order to solve the repeated restart problem of the above inverter, another embodiment of the present invention further provides a second resistor R2 and a third switch tube Q3 in the photovoltaic shutdown circuit.

[0055] A first end of the second resistor R2 is coupled to the positive output terminal VOUT1+ of the photovoltaic module 1, and a second end of the second resistor R2 is coupled to the first end of the third switch Q3. The resistance of the second resistor R2 is used to represent the ratio between a second threshold voltage and a second operating current. The second threshold voltage is used to represent the ratio between the startup voltage of the inverter and the number of photovoltaic shutdown circuits in series in the photovoltaic system. The second operating current is used to represent the minimum operating current of the inverter.

[0056] The second terminal of the third switch tube Q3 is coupled to the negative output terminal VOUT1 − of the photovoltaic assembly 1 , and the control terminal of the third switch tube Q3 is coupled to the second output terminal of the undervoltage lockout module 20 .

[0057] When the auxiliary power supply unit 11 is operating normally and the data control unit 12 receives the external input activation signal von1 output by the system's component controller, it indicates that the second switch Q2 needs to be activated. However, to ensure that the input power of the photovoltaic module 1 meets the inverter's minimum operating power, the undervoltage lockout module 20 first outputs a fourth drive voltage V4 to the control terminal of the third switch Q3 to activate the third switch Q3. Since the resistance of the second resistor R2 represents the ratio between the second threshold voltage and the second operating current, and the second threshold voltage represents the ratio between the inverter's startup voltage and the number of series-connected photovoltaic shutdown circuits in the photovoltaic system, and the second operating current represents the inverter's minimum operating current, if the output current of the photovoltaic module 1 does not meet the inverter's minimum operating current after the third switch Q3 is activated, it indicates that the output power of the photovoltaic module 1 cannot meet the inverter's normal operation. Therefore, the output voltage of the photovoltaic module 1 is pulled down by the second resistor R2 to below the second threshold voltage, and the second switch Q2 is not activated. Only when the output current of the photovoltaic assembly 1 is greater than or equal to the second operating current, the minimum operating current of the inverter, will the output voltage of the photovoltaic assembly 1 be greater than the second threshold voltage, thereby ensuring normal operation of the inverter. At this time, the undervoltage lockout module 20 outputs a fifth drive voltage V5 to the control terminal of the third switch Q3 to turn off the third switch Q3, and outputs a second turn-on signal von2 to the data control unit 12. After receiving the second turn-on signal von2 and the external input turn-on signal von1, the data control unit 12 outputs a first drive control signal v1 to the drive unit 13. Based on the first drive control signal v1, the drive unit 13 outputs a third drive voltage V3 to the control terminal of the second switch Q2 to turn on the second switch Q2.

[0058] Specifically, because the inverter's minimum operating power is greater than the sum of the minimum operating powers of the series-connected photovoltaic shutdown circuits in the system, the second threshold voltage is greater than the first threshold voltage, and the second operating current is greater than the first operating current. For example, if the first threshold voltage is 12V and the first operating current is 10mA, the second threshold voltage will reach 15V and the second operating current will reach 20mA. Of course, this is merely an example, and the values ​​of the first threshold voltage, the second threshold voltage, the first operating current, and the second operating current are determined by actual applications and are not limited here.

[0059] It should be supplemented that, if the data control unit 12 does not receive the external input turn-on signal von1, or the data control unit 12 receives the external input turn-on signal von1 but does not receive the second turn-on signal von2, the data control unit 12 outputs a second drive control signal to the drive unit 13. The drive unit 13 outputs a sixth drive voltage to the control end of the second switch tube Q2 according to the second drive control signal to turn off the second switch tube Q2.

[0060] In summary, the photovoltaic shutdown circuit provided in this embodiment avoids the problem of repeated restart of the inverter in the system.

[0061] Figure 5 2 is a schematic diagram of the system structure of a photovoltaic system provided by another embodiment of the present invention.

[0062] Please refer to Figure 4 and Figure 5 Another embodiment of the present invention provides a photovoltaic system, the photovoltaic system comprising: a system controller 4, a plurality of photovoltaic modules 1 and a plurality of Figure 4 The photovoltaic shutdown circuit 3 and the inverter 2 provided in the illustrated embodiment.

[0063] The system controller 4 is configured to output a third on-state signal von3 according to an external control signal.

[0064] The plurality of photovoltaic assemblies 1 correspond to the plurality of photovoltaic shutdown circuits 3 on a one-to-one basis, and the positive output terminal VOUT1+ of the photovoltaic assemblies 1 is coupled to the positive input terminal VOUT2+ of the corresponding photovoltaic shutdown circuit 3, and the negative output terminal VOUT1- of the photovoltaic assemblies 1 is coupled to the negative output terminal VOUT2- of the photovoltaic shutdown circuit 3. The plurality of photovoltaic shutdown circuits 3 are connected in series, and the positive output terminal VOUT2+ of the first photovoltaic shutdown circuit 3 is coupled to the output terminal of the system controller 4, and the negative output terminal VOUT2- of the photovoltaic shutdown circuit 3 is coupled to the positive output terminal VOUT2+ of the adjacent photovoltaic shutdown circuit 3.

[0065] The inverter 2 has a negative input terminal VOUT3 − coupled to the negative output terminal of the last photovoltaic shutdown circuit 3 , and a positive input terminal VOUT3+ coupled to the system controller 4 .

[0066] In the photovoltaic system provided in this embodiment, the inverter 2 operates normally only when the system controller 4 outputs the third activation signal von3 and the total module power output by the plurality of photovoltaic modules 1 reaches the minimum operating power of the inverter 2 .

[0067] 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above 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 shutdown circuit, characterized in that: Used to control the shutdown of photovoltaic components, the photovoltaic shutdown circuit includes: A photovoltaic shutdown module, the photovoltaic shutdown module is used to: According to the first enable signal, the device operates normally to control the on / off of the DC path of the photovoltaic assembly; stopping operation and shutting down a DC path of the photovoltaic assembly according to a second enable signal; an undervoltage lockout module, configured to compare the input voltage of the photovoltaic module with a first threshold voltage; if the input voltage is greater than the first threshold voltage, the undervoltage lockout module outputs a first driving voltage and the first enable signal; if the input voltage is less than the first threshold voltage, the undervoltage lockout module outputs a second driving voltage and the second enable signal; the first threshold voltage is used to represent the starting voltage of the photovoltaic shutdown module; a first resistor, wherein a first end of the first resistor is coupled to the positive output terminal of the photovoltaic assembly, and a resistance value of the first resistor is used to represent a ratio between the first threshold voltage and a first operating current, and the first operating current is used to represent a minimum operating current of the photovoltaic shutdown module; a first switch tube, wherein a first end of the first switch tube is coupled to the second end of the first resistor, a second end of the first switch tube is coupled to the negative output end of the photovoltaic component, a control end of the first switch tube is coupled to the first output end of the undervoltage lockout module, and the first switch tube is turned off according to the first driving voltage and turned on according to the second driving voltage.

2. The photovoltaic shutdown circuit according to claim 1, characterized in that: The photovoltaic shutdown module includes an auxiliary power supply unit, a data control unit, a second switch tube, a driving unit and an output capacitor; The auxiliary power supply unit is used to perform voltage conversion on the input voltage of the photovoltaic assembly and output a supply voltage, and the supply voltage is used to power various modules and units in the photovoltaic shutdown circuit. The first threshold voltage is used to represent the starting voltage of the auxiliary power supply unit, and the first operating current is used to represent the minimum operating current of the auxiliary power supply unit; The data control unit is configured to output a first drive control signal when simultaneously receiving an external input opening signal and a second opening signal; The driving unit is configured to output a third driving voltage according to the first driving control signal; A first terminal of the second switch tube is coupled to the positive output terminal of the photovoltaic assembly, a second terminal of the second switch tube is coupled to the first terminal of the output capacitor, a control terminal of the second switch tube is coupled to the output terminal of the driving unit, and the second switch tube is turned on according to the third driving voltage; The second terminal of the output capacitor is coupled to the negative output terminal of the photovoltaic component.

3. The photovoltaic shutdown circuit according to claim 2, characterized in that: The photovoltaic shutdown circuit further includes: a second resistor and a third switch tube; A first end of the second resistor is coupled to the positive output terminal of the photovoltaic module, and a second end of the second resistor is coupled to the first end of the third switch. The resistance of the second resistor is used to represent the ratio between a second threshold voltage and a second operating current. The second threshold voltage is used to represent the ratio between a starting voltage of an inverter in a photovoltaic system and the number of photovoltaic shutdown circuits in series in the photovoltaic system. The second operating current is used to represent the minimum operating current of the inverter. The second end of the third switch tube is coupled to the negative output end of the photovoltaic assembly, and the control end of the third switch tube is coupled to the second output end of the undervoltage lockout module; The undervoltage lockout module is further configured to: When the data control unit receives the external input turn-on signal, the data control unit outputs a fourth driving voltage to the control terminal of the third switch tube to turn on the third switch tube; After the third switch tube is turned on, if the input voltage of the photovoltaic component is greater than the second threshold voltage, a fifth driving voltage is output to the control end of the third switch tube to turn off the third switch tube and output the second turn-on signal to the data control unit.

4. The photovoltaic shutdown circuit according to claim 3, characterized in that: The data control module is further configured to output a second driving control signal to the driving unit when the second activation signal is not received; The driving unit is further configured to output a sixth driving voltage to the control terminal of the second switch tube according to the second driving control signal, so as to turn off the second switch tube.

5. The photovoltaic shutdown circuit according to claim 4, characterized in that: The first switch tube, the second switch tube and the third switch tube each include at least an NMOS tube.

6. The photovoltaic shutdown circuit according to claim 2, characterized in that: The driving unit includes a charge pump and a driving subunit; The charge pump is used to boost the supply voltage and output the boosted voltage to the driver sub-unit. The driver sub-unit outputs a second high drive voltage and a second floating voltage based on the boosted voltage and the first drive control signal. The second high drive voltage acts on the control terminal of the second switch tube, and the second floating voltage acts on the second terminal of the second switch tube. The second high drive voltage is greater than the second floating drive voltage, and the difference between the second high drive voltage and the second floating voltage is equal to the third drive voltage.

7. The photovoltaic shutdown circuit according to claim 2, characterized in that: The photovoltaic shutdown module also includes a signal receiving module and a signal transformer; The signal transformer is used to receive a third activation signal transmitted by the system; The signal receiving module is used to perform first signal processing on the third activation signal respectively, and output the external input activation signal.

8. The photovoltaic shutdown circuit according to claim 7, characterized in that: The photovoltaic shutdown module also includes a temperature detection module, an analog-to-digital conversion module and a signal sending module; The temperature detection module is used to convert the temperature in the circuit into a first digital signal and output it to the data control module; The analog-to-digital conversion module is used to convert the sampled voltage of the output voltage of the photovoltaic module into a second digital signal and output it to the data control module; The data control module is used to read the signal according to the external input data, and output the first digital signal and the second digital signal to the signal sending module respectively. The signal sending module is configured to perform second signal processing on the first digital signal and output a third digital signal, and to perform second signal processing on the second digital signal and output a fourth digital signal.

9. A photovoltaic system, characterized in that: include: a system controller configured to output a third activation signal according to an externally input control signal; a plurality of photovoltaic assemblies and a plurality of photovoltaic shutdown circuits according to any one of claims 2 to 8, wherein the plurality of photovoltaic assemblies and the plurality of photovoltaic shutdown circuits correspond one to one, and the positive output terminal of each photovoltaic assembly is coupled to the positive input terminal of the corresponding photovoltaic shutdown circuit, the negative output terminal of each photovoltaic assembly is coupled to the negative output terminal of the photovoltaic shutdown circuit, the plurality of photovoltaic shutdown circuits are connected in series, the positive output terminal of a first photovoltaic shutdown circuit is coupled to the output terminal of the system controller, and the negative output terminal of each photovoltaic shutdown circuit is coupled to the positive output terminal of an adjacent photovoltaic shutdown circuit; An inverter, wherein a negative input terminal of the inverter is coupled to a negative output terminal of the last photovoltaic shutdown circuit, and a positive input terminal of the inverter is coupled to the system controller.

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