A shutdown circuit for a photovoltaic switch

Abstract

This invention proposes a turn-off circuit for a photovoltaic (PV) power switch, belonging to the field of PV power generation technology. It includes a turn-off module, a control module, and a data acquisition module. The turn-off module comprises a multi-stage series-connected transistor switch. The data acquisition module communicates with the control module, and the control module communicates with the first-stage transistor switch. The last-stage transistor switch is connected to the input line of the PV power switch. The data acquisition module is used to acquire the current, voltage, or temperature of the last-stage transistor switch on the input line of the PV power switch. This invention uses a multi-stage series-connected transistor switch. When one transistor switch is turned off, the connection between the PV module and the inverter is cut off, thus providing multi-stage isolation and redundant disconnection paths in high-voltage circuits. Furthermore, the multi-stage transistor switch improves the reliability and disconnection capability of the turn-off action between the PV module and the inverter.

Description

Technical Field

[0001] This utility model belongs to the field of photovoltaic power generation technology, and relates to photovoltaic shutdown technology, specifically a shutdown circuit for a photovoltaic shutdown device. Background Technology

[0002] Photovoltaic modules are the core power generation units of a photovoltaic power generation system. Their main function is to directly convert solar energy into direct current (DC) electricity, and they are the basic components that make up a photovoltaic array. Under sunlight, photovoltaic modules continuously generate high-voltage DC electricity. Even if the inverter is turned off or the power grid is disconnected, the DC-side cables will still be energized, posing a very high safety risk to maintenance work or fire rescue.

[0003] Photovoltaic power cut-off devices are crucial equipment for ensuring the safe operation of photovoltaic systems. These devices can quickly cut off dangerous high-voltage DC power during emergencies or maintenance work, resolving the inherent "electrification" hazard of photovoltaic systems and effectively protecting the safety of firefighters, maintenance personnel, and related property.

[0004] Photovoltaic shutdown devices include string-level shutdown devices and module-level shutdown devices. In practical applications, the choice between string-level and module-level shutdown devices typically depends on system design requirements, project budget, and security level requirements. Among them, photovoltaic module-level shutdown devices can provide a higher level of security and are therefore more widely used in practice.

[0005] Existing photovoltaic module-level shutdown devices mostly use remote control to achieve rapid power-off, and their internal shutdown modules typically only contain a single-channel disconnect switch. If this switch malfunctions and sticks together, the shutdown action will be incomplete, resulting in the electrical connection between the photovoltaic module and the inverter not being reliably severed, posing a safety hazard. Utility Model Content

[0006] As described in the background section, most existing photovoltaic (PV) power-off devices use single-circuit disconnect switches for their shutdown modules. During use, if the single-circuit disconnect switch sticks together, the shutdown will be incomplete. Therefore, existing PV power-off devices have the technical problem of unreliable shutdown between the PV module and the inverter. To address this technical problem, this utility model proposes a shutdown circuit for PV power-off devices.

[0007] This invention features a multi-stage series-connected tube switch. When one of the tube switches is turned off, the connection between the photovoltaic module and the inverter is cut off, thereby providing multi-stage isolation and redundant disconnection paths in the high-voltage circuit. The multi-stage tube switch enhances the reliability and disconnection capability of the shutdown action between the photovoltaic module and the inverter.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] A shutdown circuit for a photovoltaic (PV) shutdown device includes a shutdown module, a control module, and a data acquisition module. The shutdown module includes a multi-stage transistor switch connected in sequence. The data acquisition module communicates with the control module, and the control module communicates with the first-stage transistor switch. The last-stage transistor switch is connected to the input line of the PV shutdown device. The data acquisition module is used to acquire the current, voltage, or temperature of the last-stage transistor switch on the input line of the PV shutdown device.

[0010] Further specifying, the shutdown module includes three transistor switches, namely a first transistor switch Q1, a second transistor switch Q2, and a third transistor switch Q3. The second transistor switch Q2 communicates with the control module. The second transistor switch Q2, the first transistor switch Q1, and the third transistor switch Q3 are connected sequentially from front to back. The third transistor switch Q3 is connected to the input line of the photovoltaic shutdown device.

[0011] Further specifying, the second transistor switch Q2 is a bipolar transistor switch, the first transistor switch Q1 is a PMOS transistor switch, and the third transistor switch Q3 is an NMOS transistor switch.

[0012] Further specifying, the acquisition module includes a current acquisition unit, a voltage acquisition unit, and a temperature acquisition unit. The current acquisition unit and the voltage acquisition unit are both connected to the input line of the photovoltaic switch, the temperature acquisition unit is connected to the last stage switch, and the current acquisition unit, the voltage acquisition unit, and the temperature acquisition unit also communicate with the control module.

[0013] Furthermore, the shutdown circuit for the photovoltaic switch also includes a power extraction module, which is connected to the photovoltaic module and is used to extract power from the photovoltaic module; the power extraction module is also connected to the control module and one or more of its transistor switches, and is used to supply power to the control module and its one or more transistor switches.

[0014] Further specifying, the power extraction module includes a step-down chip, a high-voltage power supply unit, a first power supply unit, a second power supply unit, and an output unit. The high-voltage power supply unit is connected to the photovoltaic module and is used to extract power from the photovoltaic module.

[0015] The high-voltage power supply unit is connected to the step-down chip. Both the first power supply unit and the second power supply unit are connected to the step-down chip. The step-down chip is connected to the output unit. The output unit is connected to the control module and one or more transistor switches therein, and is used to supply power to the control module and one or more transistor switches therein.

[0016] Furthermore, the power supply module also includes a current limiting unit, which is connected between the step-down chip and the output unit.

[0017] Furthermore, the power supply module also includes a first feedback unit and a second feedback unit, which are connected in parallel between the step-down chip and the output unit.

[0018] Furthermore, the power supply module also includes a compensation unit, which is connected between the step-down chip and the output unit.

[0019] Furthermore, the power acquisition module also includes a power supply patch unit, which is connected between the high-voltage power supply unit and the output unit.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0021] 1. This utility model provides a shutdown circuit for a photovoltaic (PV) power-off switch, comprising a shutdown module, a control module, and a data acquisition module. The data acquisition module collects the operating parameters of the PV module and sends them to the control module. The control module determines whether there is an abnormality in the PV module based on the collected parameters and controls the shutdown module accordingly. This utility model integrates both the control module and the data acquisition module within the power-off switch, changing the reliance on remote control in existing technologies and effectively avoiding control failures caused by signal distortion, transmission faults, etc. More importantly, the circuit incorporates multiple series-connected transistor switches. Turning off any one of these switches cuts off the path between the PV module and the inverter, thus providing multi-level isolation and redundant disconnection paths in the high-voltage circuit, significantly improving the reliability and disconnection capability of the shutdown action.

[0022] 2. The acquisition module includes a current acquisition unit, a voltage acquisition unit, and a temperature acquisition unit. When the control module detects an abnormality in any of the current, voltage, or temperature values ​​acquired by the acquisition units, it can determine that the photovoltaic module is malfunctioning and then control the shutdown module to shut down. By comprehensively judging multiple parameters, the accuracy and reliability of anomaly detection are significantly improved.

[0023] 3. The shutdown circuit of this utility model also includes a power-taking module, which is connected to the photovoltaic module and is used to directly take power from the photovoltaic module and supply power to the control module and one or more tube switches therein, thereby realizing the self-powering of the shutdown circuit by the photovoltaic module without the need for an external power source, thus improving the system independence and deployment flexibility.

[0024] 4. The power extraction module includes a step-down chip, a high-voltage power supply unit, a first power supply unit, a second power supply unit, and an output unit. The high-voltage power supply unit is connected to the photovoltaic module to obtain input electrical energy; the second power supply unit is a supplementary circuit to the first power supply unit; and the output unit provides power to the shutdown module and the control module. Through the compensation function of the second power supply unit, the system power supply can be ensured to be sufficient and stable, thereby realizing a high-voltage DC power extraction scheme suitable for photovoltaic shutdown devices.

[0025] 5. The power supply module of this utility model has a current limiting unit set between the step-down chip and the output unit, which can prevent the output current of the step-down chip from exceeding the set threshold, thereby effectively protecting the shutdown module from damage caused by short circuit, overload or abnormal working state.

[0026] 6. The power supply module of this utility model further includes a first feedback unit and a second feedback unit, which are connected in parallel between the output terminal of the step-down chip and the output unit, and cooperate with the current limiting unit to protect the shutdown module. Specifically, the feedback unit is used to detect the current value provided by the first power supply unit and the second power supply unit to the output module, and feeds the current back to the step-down chip. The step-down chip compares the feedback current with a preset current threshold. When an abnormality is detected, it controls the current limiting unit to blow, thereby ensuring the safe operation of the shutdown module.

[0027] 7. The power supply module of this utility model also includes a compensation unit connected between the step-down chip and the output unit, which is used to ensure the stable operation of the step-down chip, prevent the occurrence of oscillation, and further improve the circuit stability.

[0028] 8. The power supply module of this utility model is further provided with a power supply patch unit connected between the high-voltage power supply unit and the output unit, which serves as a backup path. When the step-down chip fails, power can continue to be supplied to the shutdown module through an external additional circuit without changing the original circuit structure, thereby further improving the reliability and fault tolerance of the system power supply. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the power extraction module of the present invention used in a photovoltaic switch.

[0030] Figure 2 This is a schematic diagram of the shutdown module.

[0031] Figure 3 Schematic diagram of the power supply module Figure 1 ;

[0032] Figure 4 Schematic diagram of the power supply module Figure 2 . Detailed Implementation

[0033] The technical solution of this utility model will be further explained and described below with reference to the accompanying drawings and embodiments, but this utility model is not limited to the embodiments described below.

[0034] See Figure 1 This invention provides a shutdown circuit for a photovoltaic (PV) power-off device, including a shutdown module, a control module, and a data acquisition module. The shutdown module includes a multi-stage transistor switch connected in sequence. The data acquisition module communicates with the control module, and the control module communicates with the first-stage transistor switch. The last-stage transistor switch is connected to the input line of the PV power-off device. The data acquisition module is used to acquire the current, voltage, or temperature of the last-stage transistor switch on the input line of the PV power-off device. This invention incorporates a shutdown module, a control module, and a data acquisition module. The data acquisition module collects the operating parameters of the PV module and sends these parameters to the control module. The control module uses these operating parameters to determine if there is an abnormality in the PV module and controls the shutdown module to operate accordingly. By integrating both the control module and the data acquisition module within the PV power-off device, this invention changes the existing remote control method and avoids control failures caused by signal distortion and transmission problems common in existing remote control systems.

[0035] In this invention, the control module is a commercially available conventional product, specifically an STM32WLE5CC chip.

[0036] The number of transistor switches included in the shutdown circuit can be two, three, or four stages, and the type of transistor switch can be a diode switch, a transistor switch, a MOSFET switch, or other electronic switches well known to those skilled in the art. Those skilled in the art can select the number and type of transistor switches based on experience when implementing a structure and function that are the same as or similar to that of this utility model.

[0037] See Figure 2In a preferred embodiment of this utility model, the shutdown module includes a three-transistor switch, namely a first switch Q1, a second switch Q2, and a third switch Q3. The second switch Q2 communicates with the control module. The second switch Q2, the first switch Q1, and the third switch Q3 are connected sequentially from front to back. The third switch Q3 is connected to the input line of the photovoltaic shutdown device. Specifically, the second switch Q2 is an NPN transistor switch, the first switch Q1 is a PMOS transistor switch, and the third switch Q3 is an NMOS transistor switch. When the shutdown module is not shut down, the control module outputs a high level, causing the second switch Q2 to conduct and output a low level, which in turn causes the first switch Q1 to also conduct and output a high level, resulting in the third switch Q3 conducting. Conversely, when the shutdown module is shut down, the control module outputs a low level, causing the second switch Q2, the first switch Q1, and the third switch Q3 to all turn off, or at least one of them to be able to turn off. This invention features a three-stage switching system. When one of the switches is turned off, the connection between the photovoltaic module and the inverter is cut off, thereby providing multi-stage isolation and redundant disconnection paths in the high-voltage circuit. The multi-stage switching system further enhances the reliability and disconnection capability of the shutdown action between the photovoltaic module and the inverter.

[0038] See Figure 1 The data acquisition module includes a current acquisition unit, a voltage acquisition unit, and a temperature acquisition unit. The current and voltage acquisition units are connected to the input lines of the photovoltaic (PV) switch, and the temperature acquisition unit is connected to the last stage switch. All three units also communicate with the control module. The current acquisition unit acquires the current value of the PV module, the voltage acquisition unit acquires the voltage value, and the temperature acquisition unit acquires the temperature value. The control module sets current, voltage, and temperature thresholds. The current, voltage, and temperature values ​​acquired by each unit are sent to the control module. The control module compares each value with its respective threshold. If the control module determines that any one of these values ​​is abnormal, it indicates a problem with the PV module and controls the shutdown module to turn it off. This invention improves the accuracy and reliability of the judgment by using multiple factors, including current, voltage, and temperature.

[0039] See Figure 3 and Figure 4 The shutdown circuit of this utility model for a photovoltaic shutdown device also includes a power extraction module, which is connected to the photovoltaic module and is used to extract power from the photovoltaic module; the power extraction module is connected to the control module and one or more of the tube switches therein, and is used to supply power to the control module and one or more of the tube switches therein.

[0040] In a preferred embodiment of this utility model, the power extraction module includes a step-down chip, a high-voltage power supply unit, a first power supply unit, a second power supply unit, and an output unit. The high-voltage power supply unit is connected to the photovoltaic module and is used to extract power from the photovoltaic module. The high-voltage power supply unit is connected to the step-down chip, and both the first power supply unit and the second power supply unit are connected to the step-down chip. The step-down chip is connected to the output unit, and the output unit is connected to the control module and one or more transistor switches therein, and is used to supply power to the control module and one or more transistor switches therein.

[0041] In this invention, the input voltage of the step-down chip reaches a maximum of 300V. Figure 3 In the high-voltage power supply unit, there are diode D11 and electrolytic capacitor CE1. Diode D11 is connected to the positive terminal of the photovoltaic module, and electrolytic capacitor CE1 is connected to the negative terminal of the photovoltaic module. The step-down chip includes ports DRAIN1, DRAIN2, DRAIN3, DRAIN4, DRAIN5, GND, VDD, LIM, FB, and COMP. DRAIN1, DRAIN2, DRAIN3, DRAIN4, and DRAIN5 of the step-down chip are all connected between diode D11 and electrolytic capacitor CE1. The negative terminal of the photovoltaic module is grounded, and port GND is grounded.

[0042] The first power supply unit includes a capacitor C11, one end of which is connected to the port VDD, and the other end is connected to the output unit. The second power supply unit includes a diode D2, a capacitor C12, and a capacitor C13. One end of capacitor C12 and one end of capacitor C13 are both connected to the port VDD of the step-down chip through diode D2. The other ends of capacitor C12 and capacitor C13 are both connected to the output unit.

[0043] Preferably, the connection terminals of capacitor C11 and the output unit, capacitor C12 and the output unit, and capacitor C13 and the output unit are connected to an inductor L1, which can filter the voltage.

[0044] In this invention, the step-down chip is a DC-DC step-down chip, model VIPER06XS, and its output is 12V. That is, the step-down chip reduces the 300V voltage to 12V to power the shutdown module.

[0045] In this invention, the second power supply unit is a supplementary circuit to the first power supply unit, and the output unit supplies power to the shutdown module of the photovoltaic shutdown device, thereby realizing a power supply circuit applicable to the shutdown module on thin-film photovoltaics. At the same time, the supplementary function of the second power supply unit ensures sufficient and stable power supply.

[0046] In this invention, the power supply module also includes a current limiting unit, which is connected between the step-down chip and the output unit. Specifically, in Figure 3 and Figure 4 In the current limiting unit, there is a resistor R46. One end of the resistor R46 is connected to the port LIM, and the other end is connected to the output unit through the inductor L1. The current limiting unit can prevent the current of the buck chip from exceeding the set threshold and protect the shutdown module from damage caused by short circuit, overload or abnormal working conditions.

[0047] In this invention, the power supply module further includes a first feedback unit and a second feedback unit, which are connected in parallel between the port FB of the step-down chip and the output unit. The first feedback unit includes a resistor R30; the second feedback unit includes a resistor R63 and a diode D4. Resistor R30 is connected to one end of inductor L1, and diode D4 is connected to the other end of inductor L1. Resistor R30 is connected to the output unit through inductor L1, and diode D4 is directly connected to the output unit. Diode D4 is connected to resistor R63. Both resistors R30 and R63 are connected to port FB. Both the first and second feedback units are used to detect the current value supplied to the output module by the first and second power supply units and feed this current value back to the step-down chip. The step-down chip compares this current value with a set current threshold. When the comparison result indicates an abnormal current, the step-down chip controls the current limiting unit to melt, thereby protecting the shutdown module.

[0048] Preferably, the power extraction module further includes a voltage regulator unit, with the second feedback unit connected to the voltage regulator unit, and the other end of the voltage regulator unit grounded. The voltage regulator unit includes an electrolytic capacitor CE2, one end of which is connected to the output terminal of the inductor L1, and the other end of which is grounded. The voltage regulator module enables a stable output of the voltage filtered by the inductor L1 to the power consumption module of the photovoltaic switch. Diode D4 is connected to the electrolytic capacitor CE2.

[0049] In this invention, the power supply module also includes a compensation unit. The compensation unit is connected between the COMP port of the step-down chip and the output unit. The compensation unit includes a capacitor C16 and a resistor R28. One end of the resistor R28 is connected to the COMP port, and the other end of the resistor R28 is connected to one end of the capacitor C16. The other end of the capacitor C16 is connected to the output unit through an inductor L1. The compensation unit ensures the stable operation of the step-down chip and avoids oscillation.

[0050] In this invention, the power supply module also includes a load unit R71. One end of the load unit R71 is connected to the inductor L1, and the other end of the load unit R71 is grounded. Specifically, the load unit R71 serves as a current shunt, diverting a small current to improve the no-load stability of the output unit.

[0051] The output unit includes a resistor R33. One end of resistor R33 is connected to the output terminal of inductor L1, and the other end of resistor R33 can be connected to the power module. The resistance of resistor R33 is 0Ω, and it is used as a connecting element or jumper in the circuit.

[0052] See Figure 4 In this invention, the power supply module further includes a power supply patch unit, which is connected between the positive terminal of the photovoltaic module and the step-down chip. The power supply patch unit includes, from front to back, resistors R19, R21, and R24, and diode D3. Resistor R19 is connected to the positive terminal of the thin-film photovoltaic, resistor R24 ​​is connected to the VDD port, and diode D3 is connected in parallel with capacitor C11. Diode D3 is a Zener diode. The power supply patch unit serves as a backup; when the power supply to the step-down chip from the first and second power supply units malfunctions, it can supply power to the step-down chip without altering its original circuit layout, further improving power supply stability.

[0053] In this invention, the power supply module has an input of 300V and an output of 12V, which matches the input of the shutdown module and the control module. For those skilled in the art, if the selected control module has an input of 5V or 3.3V, they can, based on experience, add a step-down module connected to the output of the power supply module, thereby matching the output of the power supply module with the input of the control module. Specifically, the added step-down module is preferably a commercially available existing step-down module.

[0054] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A turn-off circuit for a photovoltaic turn-off switch, characterized by It includes a shutdown module, a control module, and a data acquisition module. The shutdown module includes a multi-stage transistor switch connected in sequence. The data acquisition module communicates with the control module, and the control module communicates with the first-stage transistor switch. The last-stage transistor switch is connected to the input line of the photovoltaic shutdown device. The data acquisition module is used to acquire the current, voltage, or temperature of the last-stage transistor switch on the input line of the photovoltaic shutdown device.

2. The turn-off circuit for a photovoltaic turn-off according to claim 1, characterized in that, The shutdown module includes three transistor switches: a first transistor switch Q1, a second transistor switch Q2, and a third transistor switch Q3. The second transistor switch Q2 communicates with the control module. The second transistor switch Q2, the first transistor switch Q1, and the third transistor switch Q3 are connected sequentially from front to back. The third transistor switch Q3 is connected to the input line of the photovoltaic shutdown device.

3. The turn-off circuit for a photovoltaic turn-off according to claim 2, characterized in that, The second transistor switch Q2 is a bipolar transistor switch, the first transistor switch Q1 is a PMOS transistor switch, and the third transistor switch Q3 is an NMOS transistor switch.

4. The turn-off circuit for a photovoltaic turn-off according to claim 1, characterized in that, The acquisition module includes a current acquisition unit, a voltage acquisition unit, and a temperature acquisition unit. The current acquisition unit and the voltage acquisition unit are both connected to the input line of the photovoltaic switch, and the temperature acquisition unit is connected to the last stage switch. The current acquisition unit, the voltage acquisition unit, and the temperature acquisition unit also communicate with the control module.

5. The turn-off circuit for a photovoltaic turn-off according to any one of claims 1 to 4, characterized in that, The shutdown circuit for the photovoltaic shutdown device also includes a power extraction module, which is connected to the photovoltaic module and is used to extract power from the photovoltaic module; the power extraction module is also connected to the control module and one or more of its transistor switches, and is used to supply power to the control module and its one or more transistor switches.

6. The turn-off circuit for a photovoltaic turn-off according to claim 5, characterized in that, The power extraction module includes a step-down chip, a high-voltage power supply unit, a first power supply unit, a second power supply unit, and an output unit. The high-voltage power supply unit is connected to the photovoltaic module and is used to extract power from the photovoltaic module. The high-voltage power supply unit is connected to the step-down chip. Both the first power supply unit and the second power supply unit are connected to the step-down chip. The step-down chip is connected to the output unit. The output unit is connected to the control module and one or more transistor switches therein, and is used to supply power to the control module and one or more transistor switches therein.

7. The turn-off circuit for a photovoltaic turn-off according to claim 6, characterized in that, The power supply module also includes a current limiting unit, which is connected between the step-down chip and the output unit.

8. The turn-off circuit for a photovoltaic turn-off according to claim 6, characterized in that, The power supply module further includes a first feedback unit and a second feedback unit, which are connected in parallel between the step-down chip and the output unit.

9. The turn-off circuit for a photovoltaic turn-off according to claim 6, characterized in that, The power supply module also includes a compensation unit, which is connected between the step-down chip and the output unit.

10. The turn-off circuit for a photovoltaic turn-off according to claim 6, characterized in that, The power acquisition module also includes a power supply patch unit, which is connected between the high-voltage power supply unit and the output unit.

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