Overvoltage protection circuit, optimizer, turn-off device and photovoltaic system

Abstract

The utility model discloses an overvoltage protection circuit, an optimizer, a turn-off device and a photovoltaic system, and the protection circuit composed of a drive circuit and a switching circuit is arranged at the input end and / or the output end of power conversion equipment. The driving circuit can drive the second end and the third end of the switching circuit to be connected when the voltage of the specified port of the power conversion equipment is larger than the preset voltage threshold value, so that the input end and / or the output end are / is short-circuited, and the equipment is protected.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, in particular to an overvoltage protection circuit, an optimizer, a shutdown device and a photovoltaic system. Background Art

[0002] Currently, input terminals can become open due to loose ports, manual disassembly, or failure, which can, in some cases, lead to damage from overvoltage. For example, in photovoltaic scenarios, if the input of an optimizer or circuit breaker becomes open due to these reasons, the inverter voltage or the voltage of another string in the parallel string will circulate, causing energy from the optimizer's output to flow back to the input terminal. This will generate a high voltage at the input terminal, potentially damaging the optimizer or circuit breaker. Utility Model Content

[0003] Based on the above problems, the present application provides an overvoltage protection circuit, an optimizer, a shutdown device and a photovoltaic system to solve the problem that an open circuit at the input terminal may cause equipment damage under certain working conditions.

[0004] The embodiments of this application disclose the following technical solutions:

[0005] In a first aspect, an embodiment of the present application provides an overvoltage protection circuit, comprising: a drive circuit and a switch circuit; the drive circuit is connected to a first end of the switch circuit; the drive circuit is configured to be connected in parallel to a designated port of a power conversion device to be protected; a second end of the switch circuit is connected to a positive electrode of the designated port of the power conversion device, and a third end of the switch circuit is connected to a negative electrode of the designated port of the power conversion device, where the designated port is at least one of an input end or an output end of the power conversion device;

[0006] The driving circuit is configured to drive the second terminal and the third terminal of the switch circuit to conduct in response to the voltage of the designated port being greater than a preset voltage threshold, wherein the preset voltage threshold is greater than the normal operating voltage of the designated port.

[0007] Optionally, the driving circuit includes a Zener diode and a capacitor, the first end of the Zener diode is connected to the first end of the switching circuit, the second end of the Zener diode is connected to the positive electrode of the designated port, the first end of the Zener diode is connected to the first end of the capacitor, and the second end of the capacitor is connected to the negative electrode of the designated port.

[0008] Optionally, the driving circuit further includes a first resistor, a second resistor, a third resistor, a fourth resistor, a second voltage regulator diode, a first switching device, and a second switching device;

[0009] Among them, the first end of the first resistor is connected to the second end of the second resistor and the first end of the first switching device, the second end of the first resistor is connected to the positive electrode of the designated port, the first end of the second resistor is connected to the third end of the second switching device, the first end of the third resistor is connected to the second end of the fourth resistor and the first end of the voltage regulator, the second end of the third resistor is connected to the third end of the first switching device, the first end of the fourth resistor is connected to the first end of the second switching device and the first end of the capacitor, the second end of the first switching device is connected to the second end of the voltage regulator and the positive electrode of the designated port, the second end of the second switching device is connected to the second end of the capacitor, the second end of the capacitor is connected to the second end of the second voltage regulator and the negative electrode of the designated port, and the first end of the voltage regulator is connected to the second end of the second voltage regulator and the first end of the switching circuit.

[0010] Optionally, the driving circuit further includes: a fifth resistor;

[0011] Among them, the first end of the voltage regulator is connected to the first end of the fifth resistor, the second end of the voltage regulator is connected to the positive electrode of the designated port, the second end of the fifth resistor is connected to the first end of the capacitor and the first end of the switching circuit, and the second end of the capacitor is connected to the negative electrode of the designated port.

[0012] Optionally, the driving circuit further includes: a sixth resistor and a diode;

[0013] The first end of the voltage regulator is connected to the first end of the sixth resistor and the first end of the diode, the second end of the voltage regulator is connected to the positive electrode of the designated port, the second end of the diode is connected to the first end of the switching circuit, the first end of the capacitor is connected to the first end of the diode, and the second end of the capacitor is connected to the second end of the sixth resistor and the negative electrode of the designated port.

[0014] Optionally, the power conversion device is a DC-DC circuit, the switching device in the switching circuit is a main power device in the DC-DC circuit, and the DC-DC circuit includes any one of the following: a step-down circuit, a buck-boost circuit, or a circuit breaker.

[0015] Optionally, the power conversion device includes an input end and an output end;

[0016] The input end and the output end are bidirectionally conductive, and the designated port includes the input end or the output end; or,

[0017] Energy is conducted unidirectionally from the output port to the input port, and the designated port includes the output port.

[0018] Optionally, the designated port includes a first designated port and a second designated port, and the drive circuit is configured to be connected in parallel to the first designated port; the second end of the switching circuit is connected to the positive pole of the second designated port, and the third end of the switching circuit is connected to the negative pole of the second designated port, the first designated port is at least one of the input end or the output end of the power conversion device, and the second designated port is at least one of the input end or the output end of the power conversion device.

[0019] Optionally, the power conversion device includes a first switching device, a first end of the first switching device is connected to the positive electrode of the designated port, and a second end of the first switching device is connected to the negative electrode of the designated port.

[0020] Optionally, the power conversion device includes a third switching device and a fourth switching device, the first end of the third switching device is connected to the positive pole of the output end of the power conversion device, the second end of the third switching device is connected to the negative pole of the output end of the power conversion device, the first end of the fourth switching device is connected to the positive pole of the output end of the power conversion device, and the second end of the fourth switching device is connected to the first end of the third switching device.

[0021] In a second aspect, an embodiment of the present application provides an optimizer, which includes the overvoltage protection circuit as in the first aspect.

[0022] In a third aspect, an embodiment of the present application provides a circuit breaker, which includes the overvoltage protection circuit as described in the first aspect.

[0023] In a fourth aspect, an embodiment of the present application provides a photovoltaic system, the system comprising at least one optimizer and at least one inverter;

[0024] In which, the output end of the optimizer is connected to the input end of the corresponding inverter; the input end of the optimizer is connected to the output end of the corresponding photovoltaic module; the optimizer includes the overvoltage protection circuit as described in the first aspect; the inverter is used to receive the direct current output by the corresponding optimizer, and invert the direct current into alternating current to power the load.

[0025] The overvoltage protection circuit provided in the embodiment of the present application is configured by providing a protection circuit composed of a driving circuit and a switching circuit at the input end and / or the output end. When a higher voltage is generated at the input end due to an open circuit, the driving circuit can connect the second end and the third end of the switching circuit, thereby short-circuiting the input end and / or the output end to protect the device. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0027] Figure 1 A schematic diagram of the structure of an overvoltage protection circuit provided in an embodiment of the present application;

[0028] Figure 2A schematic structural diagram of a driving circuit provided in an embodiment of the present application;

[0029] Figure 3 A first structural diagram of a driving circuit provided in an embodiment of the present application;

[0030] Figure 4 A second structural diagram of a driving circuit provided in an embodiment of the present application;

[0031] Figure 5 A third structural diagram of a driving circuit provided in an embodiment of the present application;

[0032] Figure 6 A first schematic diagram of a protection circuit connection method provided in an embodiment of the present application;

[0033] Figure 7 A second schematic diagram of a protection circuit connection method provided in an embodiment of the present application;

[0034] Figure 8 A third schematic diagram of a protection circuit connection method provided in an embodiment of the present application;

[0035] Figure 9 A fourth schematic diagram of a protection circuit connection method provided in an embodiment of the present application;

[0036] Figure 10 A schematic structural diagram of an energy storage system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] As previously described, research on various devices has revealed that the input terminals of devices can become open due to loose ports, manual disassembly, or failure. When the input terminals of devices are open, circulating current from the inverter voltage or the voltage of another string in the parallel string can cause energy from the optimizer's output to flow back to the input terminals. This energy flowing back from the output terminals can generate high voltages, leading to overvoltage damage to the device.

[0038] Taking the photovoltaic scenario as an example, the open-circuit process of the input end of the above-mentioned device is explained. It is assumed that the photovoltaic system includes an inverter and at least one optimizer. The output end of the optimizer is connected to the input end of the inverter through a DC bus. The input end of the optimizer is connected to the photovoltaic module. The output end of the inverter is used to connect the load. Among them, the photovoltaic module is used to provide DC power to the optimizer, and the optimizer is used to transfer DC power to the inverter through the DC bus. The inverter is used to convert DC power into AC power.

[0039] Based on the photovoltaic scenario described above, as an example, assume that an open circuit occurs at the optimizer input, preventing the inverter from receiving a stable input current or voltage. This open circuit may cause unstable current or abnormal voltage within the inverter, leading to arcing. The inverter then triggers the choke mechanism, shutting off the output. During this choke, the sudden change in current generates a self-induced electromotive force in the optimizer's PLC inductor and line parasitic inductance. This inductance causes the EMI (electromagnetic interference) capacitor in the inverter to charge. As the EMI capacitor charges, the voltage of the connected string gradually increases. When the voltage exceeds the rated voltage of the string, an overvoltage condition occurs. When the EMI capacitor is fully charged, its stored energy feeds back into the optimizer, further affecting the optimizer's voltage status. Before the auxiliary power source starts, the output terminal may be subjected to a transient surge of high-voltage backflow current. This high-voltage backflow current rapidly charges the output capacitor, causing the capacitor voltage to rise rapidly. If the voltage of the output capacitor exceeds the rated voltage of the MOSFET connected to it, the MOSFET may be damaged by the overvoltage.

[0040] That is, when the input of the optimizer is open and the inverter is blocked, the PLC inductor and line parasitic inductance of the optimizer charge the EMI capacitor of the inverter, causing the string to overvoltage, and then the EMI capacitor energy is fed back to the output of the optimizer. The instantaneous high-voltage backflow current at the output of the optimizer will quickly charge the capacitor of the optimizer to overvoltage before the auxiliary power source starts, causing the components in the optimizer to be damaged due to overvoltage.

[0041] Among them, PLC inductors refer to inductive components used in PLC (Programmable Logic Controller) systems. Inductors are one of the commonly used components in circuits. Their main function is to store electrical energy and hinder changes in current. In PLC systems, inductive components may be used for a variety of purposes, such as power filtering, signal isolation, energy storage and transmission, etc. EMI (Electromagnetic Interference (EMI) Capacitor), also known as EMI suppression capacitors or filter capacitors, is a capacitive component used to suppress electromagnetic interference (EMI) and radio frequency interference (RFI). Its main function is to absorb or suppress electromagnetic energy in the circuit to reduce the impact of electromagnetic interference on the circuit.

[0042] Based on the above photovoltaic scenario, as another example, assume that the input of the optimizer or circuit breaker is open. When the inverter is shut down, such as turning off the inverter's DC switch, the two optimizer strings switch to standby mode at different times. The output voltage of the string that switches to standby mode first becomes low, and current is reversed by the other high-voltage parallel string. As a result, the output of the optimizer or circuit breaker with the open input is subjected to a voltage difference, causing overvoltage damage to the device.

[0043] As another example of the aforementioned photovoltaic scenario, due to the potential for energy transfer between PV strings or between the inverter and optimizer, if energy is continuously transferred to an optimizer with an open input, the optimizer's main circuit could be damaged by overvoltage, as the open input optimizer lacks PV module clamping. Furthermore, if differential strings are connected in parallel, a natural voltage difference between the strings will be fully applied to the optimizer without PV modules connected. If the voltage difference exceeds 80V, there is a risk of damage to the optimizer.

[0044] Based on the multiple examples provided above, it can be found that the device may be damaged by overvoltage due to an open circuit at the input end. In order to solve this technical problem, an embodiment of the present application provides an overvoltage protection circuit, including: a drive circuit and a switch circuit, the drive circuit is connected to the first end of the switch circuit, the drive circuit is configured to be connected in parallel to the designated port of the power conversion device to be protected, the second end of the switch circuit is connected to the positive pole of the designated port of the power conversion device, the third end of the switch circuit is connected to the negative pole of the designated port of the power conversion device, the designated port is at least one of the input end or the output end of the power conversion device, the drive circuit is configured to drive the second end and the third end of the switch circuit to conduct in response to the voltage of the designated port being greater than a preset voltage threshold, wherein the preset voltage threshold is greater than the normal working voltage of the designated port.

[0045] In this way, by setting a protection circuit composed of a driving circuit and a switching circuit at the input end and / or the output end, when the input end generates a higher voltage due to an open circuit, for example, the input end of the optimizer may generate voltage accumulation due to current imbalance, thereby leading to a high-voltage state, when the voltage of the driving circuit at the designated port is greater than the preset voltage threshold, the second end and the third end of the switching circuit can be connected, thereby short-circuiting the input end and / or the output end. That is, when the input end and / or the output end is short-circuited, a temporary current path will be formed, allowing current to flow, thereby avoiding voltage accumulation and the generation of a high-voltage state, so as to protect the device.

[0046] In order to help those skilled in the art better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0047] See also Figure 1 , this figure is a first structural schematic diagram of an overvoltage protection circuit provided in an embodiment of the present application.

[0048] Combine Figure 1As shown, the overvoltage protection circuit 100 provided in an embodiment of the present application may include: a driving circuit 101 and a switching circuit 102; the driving circuit 101 is connected to a first end of the switching circuit 102; the driving circuit 101 is configured to be connected in parallel to a designated port of a power conversion device to be protected, the second end of the switching circuit 102 is connected to the positive pole of the designated port of the power conversion device, and the third end of the switching circuit 102 is connected to the negative pole of the designated port of the power conversion device, and the designated port is at least one of the input terminal IN or the output terminal OUT of the power conversion device.

[0049] The designated port refers to a designated port among multiple ports in the power conversion device to be protected. For example, the power conversion device includes three input ports, namely IN1, IN2 and IN3. The power conversion device is connected to other devices through the input port IN3. In this case, the designated port can be the input port IN3.

[0050] Power conversion equipment refers to a power conversion device that is mainly used to convert electrical energy from one form to another to meet the energy transmission and control needs under different power requirements. For example, a circuit breaker, an optimizer, a buck circuit (Buck circuit), a buck-boost circuit (Buck-Boost circuit), etc. The input end of the power conversion device means the designated port of the power conversion device configured to receive an external input voltage. The external input voltage means the voltage provided by an external device for inputting the power conversion device. The output end of the power conversion device means the designated port where the power conversion device outputs the processed output voltage to the outside. The output voltage means the voltage provided by the external device and output by the power conversion device.

[0051] In one possible implementation, the designated port includes a first designated port and a second designated port, and the drive circuit 101 is configured to be connected in parallel to the first designated port; the second end of the switch circuit 102 is connected to the positive pole of the second designated port, and the third end of the switch circuit 102 is connected to the negative pole of the second designated port. The first designated port is at least one of the input end or the output end of the power conversion device, and the second designated port is at least one of the input end or the output end of the power conversion device.

[0052] It should be understood that the drive circuit 101 can be provided at the input, output, or both ends of the power conversion device. Similarly, the switch circuit 102 can be provided at the input, output, or both ends of the power conversion device. The drive circuit 101 and the switch circuit 102 can be provided in a variety of configurations, and different configurations can be used for different power conversion devices. The configurations of the drive circuit 101 and the switch circuit 102 will be described below with reference to specific examples, and will not be elaborated on here.

[0053] It should be noted that the embodiments of this application provide Figure 1 The example where both the driving circuit 101 and the switching circuit 102 are arranged at the output end of the power conversion device is used for illustration, but this is not used as a basis for limiting the scope of protection of this application.

[0054] The driving circuit 101 is configured to drive the second terminal and the third terminal of the switch circuit 102 to be conductive in response to the voltage of the designated port being greater than a preset voltage threshold.

[0055] The preset voltage threshold refers to a voltage range determined based on the operating voltage of the power conversion device. The preset voltage threshold is greater than the normal operating voltage of the designated port. It should be understood that the preset voltage threshold when the designated port of the power conversion device is an input port (referred to as the first preset voltage threshold) and the preset voltage threshold when the designated port of the power conversion device is an output port (referred to as the second preset voltage threshold) can be the same or different.

[0056] The operating voltage refers to the maximum voltage at which the power conversion device can operate normally, and may also be the maximum voltage at which the components in the power conversion device can operate normally, which is not specifically limited here.

[0057] The setting value of the first preset voltage threshold typically needs to take into account the power conversion device's compatibility with the power source and its protection mechanism. To ensure that the power conversion device can accept inputs from different power sources and operate stably, the setting value of the first preset voltage threshold is generally larger than the operating voltage of the power conversion device. For example, if the operating voltage of the power conversion device is 220V, the first preset voltage threshold can be 240V, 260V, etc.

[0058] The voltage at the output of the power conversion device reflects the operating state and performance of the power conversion device. To ensure that the power conversion device can output a stable and accurate voltage signal, the second preset voltage threshold is generally set to a narrower value relative to the operating voltage of the power conversion device. For example, if the operating voltage of the power conversion device is 220V, the second preset voltage threshold may be 225V, 230V, or the like. Because the accuracy of the output voltage is crucial to the normal operation of the power conversion device, excessive voltage fluctuations may affect the performance and stability of the power conversion device and even damage connected devices.

[0059] It should be understood that the first preset voltage and the second preset voltage may also be the same, for example, the first preset voltage and the second preset voltage are both 240V.

[0060] For example, when the input end of the power conversion device is open, the change process of its input end and output end is: the input end is open → the voltage of the input end gradually changes from the operating voltage to zero → the voltage of the output end gradually decreases from the operating voltage → energy is fed back to the output end → the voltage of the output end continues to increase from the current voltage (exceeding the operating voltage) → energy is fed back to the input end → the voltage of the input end continues to increase from zero (exceeding the operating voltage) → the equipment is damaged due to overvoltage.

[0061] That is, in order to achieve the purpose of protecting the device when the power conversion device is open-circuited, the voltage at the input end of the power conversion device shall not exceed the first preset voltage and the voltage at the output end of the power conversion device shall not exceed the second preset voltage; if the voltage at the input end of the power conversion device exceeds the first preset voltage or the voltage at the output end of the power conversion device exceeds the second preset voltage, it is necessary to drive the second and third ends of the switching circuit to be connected through the driving circuit.

[0062] It should be understood that in this embodiment, whether the drive circuit drives the second and third terminals of the switch circuit to connect based on the voltage at the input terminal or the voltage at the output terminal depends on the configuration of the drive circuit. As an example, assuming that the drive circuit is provided at the input terminal of the power conversion device, the drive circuit is configured to drive the second and third terminals of the switch circuit to connect when the voltage at the input terminal of the power conversion device is greater than a first preset voltage; assuming that the drive circuit is provided at the output terminal of the power conversion device, the drive circuit is configured to drive the second and third terminals of the switch circuit to connect when the voltage at the output terminal of the power conversion device is greater than a second preset voltage; assuming that the drive circuit is provided at both the input and output terminals of the power conversion device, the drive circuit is configured to drive the second and third terminals of the switch circuit to connect when the voltage at the input terminal of the power conversion device is greater than the first preset voltage or the voltage at the output terminal of the power conversion device is greater than the second preset voltage.

[0063] A switching circuit is a circuit that turns a circuit on or off, such as a metal-oxide-semiconductor field-effect transistor (MOSFET) or thyristor. A MOSFET (also known as a field-effect transistor) is a unipolar semiconductor device. A thyristor, also known as a silicon-controlled rectifier (SiC), is a high-power switching semiconductor device.

[0064] It should be understood that in the embodiment of the present application, by arranging the driving circuit and the switching circuit at the input and / or output ends of the power conversion device, when the input end of the power conversion device generates a higher voltage due to an open circuit (the voltage of the designated port of the power conversion device exceeds the preset voltage), the driving circuit can drive the second end and the third end of the switching circuit to be connected, thereby short-circuiting the input and / or output ends of the power conversion device to form a temporary current loop, avoiding the high voltage state caused by voltage accumulation, and thereby avoiding damage to the power conversion device due to overvoltage, thereby achieving the purpose of protecting the device.

[0065] See also Figure 2 , which is a structural schematic diagram of a driving circuit provided in an embodiment of the present application.

[0066] Combine Figure 2 As shown, the driving circuit 101 provided in the embodiment of the present application may include a voltage regulator tube D1 and a capacitor C1, a first end of the voltage regulator tube D1 is connected to a first end of the switch circuit 102, and a second end of the voltage regulator tube D1 is connected to the positive electrode of the designated port (i.e. Figure 2 The first end of the voltage regulator D1 is connected to the first end of the capacitor C1, and the second end of the capacitor C1 is connected to the negative electrode of the designated port (i.e. Figure 2 Vo-).

[0067] A Zener diode, also known as a voltage stabilizer, electronic voltage regulator, or Zener diode, is a semiconductor device that automatically adjusts its resistance in a circuit to maintain a constant output voltage. A Zener diode has a stable breakdown voltage. When the reverse voltage exceeds the breakdown voltage, the diode enters a breakdown state, but its voltage remains at the breakdown voltage, thus maintaining a constant voltage in the circuit. Under forward operating voltage, the Zener diode conducts normally, similar to a diode; however, when the reverse voltage exceeds its breakdown voltage, it exhibits voltage-stabilizing characteristics.

[0068] It should be noted that the Zener diode can also be replaced by devices that can achieve voltage stabilization functions, such as transistor regulators, integrated circuit regulators, switching regulators and linear regulators. However, from a cost perspective, the Zener diode is preferred.

[0069] It should be understood that the embodiments of the present application utilize the PN junction structure and reverse breakdown voltage characteristics of the Zener diode. By setting a suitable stable voltage value, when the voltage input to the second end of the Zener diode D1 (hereinafter referred to as the input voltage) is less than or equal to the stable voltage value, the Zener diode D1 is non-conductive, that is, the second and third ends of the switch circuit 102 are not connected. When the input voltage to the second end of the Zener diode D1 is greater than the stable voltage value, the Zener diode D1 breaks down, making the voltages at the first and second ends of the Zener diode D1 equal. At this time, the Zener diode D1 can drive the switch circuit 102 to connect the second and third ends of the switch circuit 102. The stable voltage value of the Zener diode D1 can be set to a preset voltage value, and the specific setting method is not limited here.

[0070] It should be noted that when the input voltage exceeds the stable voltage value of the Zener diode, it will begin to conduct and limit further voltage increases, thereby acting as a clamp to limit the input voltage to a specific voltage range. By limiting the input voltage to a specific voltage range, the circuit can be effectively protected from damage caused by excessive voltage and ensure the circuit's stability and reliability.

[0071] It should be noted that, since the voltage at the input or output end may suddenly increase after the input end of the power conversion device is opened, in order to avoid damage to the driving circuit, capacitor C1 can absorb or release part of the energy, thereby slowing down the rate of voltage change and preventing voltage mutations from damaging the switching circuit.

[0072] In an embodiment of the present application, by utilizing the reverse breakdown characteristics of the Zener diode in the driving circuit, when the input voltage at the second end of the Zener diode is greater than the stable voltage value, that is, the input end or the output end is open, the Zener diode D1 is turned on at this time, and then the switching circuit 102 can be driven to turn on, so as to short-circuit the input end or the output end of the power conversion device, forming a temporary current loop to protect the device.

[0073] See also Figure 3 , this figure is a first structural schematic diagram of a driving circuit provided in an embodiment of the present application.

[0074] Combine Figure 3 As shown, the driving circuit 101 provided in the embodiment of the present application may include: a voltage regulator diode D1, a capacitor C1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a second voltage regulator diode D2, a first switch device Q1 and a second switch device Q2.

[0075] In which, the first end of the first resistor R1 is connected to the second end of the second resistor R2 and the first end of the first switching device Q1, the second end of the first resistor R1 is connected to the positive electrode of the designated port, the first end of the second resistor R2 is connected to the third end of the second switching device Q2, the first end of the third resistor R3 is connected to the second end of the fourth resistor R4 and the first end of the voltage-stabilizing diode D1, the second end of the third resistor R3 is connected to the third end of the first switching device Q1, the first end of the fourth resistor R4 is connected to the first end of the second switching device Q2 and the first end of the capacitor C1, the second end of the first switching device Q1 is connected to the second end of the voltage-stabilizing diode D1 and the positive electrode of the designated port, the second end of the second switching device Q2 is connected to the second end of the capacitor C1, the second end of the capacitor C1 is connected to the second end of the second voltage-stabilizing diode D2 and the negative electrode of the designated port, and the first end of the voltage-stabilizing diode D1 is connected to the second end of the second voltage-stabilizing diode D2 and the first end of the switching circuit 102.

[0076] The positive pole of the designated port is Figure 3 The Vo+ shown in the figure specifies the negative terminal of the port. Figure 3 Vo- shown in .

[0077] It should be understood that, taking the example of a protection circuit consisting of a driving circuit 101 and a switching circuit 102 connected in parallel at the output end, and a MOS transistor being used as the switching circuit 102, when the voltage of Vo+ is higher than the stable voltage value of D1, the voltage regulator D1 is broken down. At this time, the voltage regulator D1 is turned on, and then drives the second switching device Q2 to turn on through D1 and R4. Then, the first switching device Q1 is turned on, and the voltage of Vo+ reaches the first end of the switching circuit 102 through the current limiting resistor R3, thereby driving the switching circuit 102 to turn on, thereby achieving a short-circuit protection effect.

[0078] It should be noted that in the embodiment of the present application, the stable voltage value of the voltage regulator diode D1 needs to be greater than the rated output voltage of the power conversion device to avoid affecting the normal operation of the power conversion device. In addition, when the first switching device Q1 is turned on, the voltage Vo+ will pass through the first switching device Q1 and the current-limiting resistor R4 to reach the first end of the switching circuit 102 (e.g., the G terminal of the MOS transistor). Because the voltage value of Vo+ is relatively high, and the voltage Vgs (the voltage difference between the gate and the source) that the first end of the switching circuit 102 can withstand generally does not exceed 20V, the second voltage regulator diode D2 is required for protection. By adjusting the stable voltage value of the second voltage regulator diode D2, damage to the switching circuit 102 due to Vgs overvoltage can be prevented.

[0079] It should be noted that if switch circuit 102 is a MOS transistor, when the driver circuit turns on the MOS transistor, the MOS transistor will pull down the voltage of Vo+. Due to the loss of driving voltage, the MOS transistor will shut down, entering a hiccup protection state, but it can still protect the device. In addition, the stable voltage value of the voltage regulator must be greater than or equal to the rated output voltage value of the power conversion device; otherwise, it may affect the normal operation of the power conversion device.

[0080] See also Figure 4 , this figure is a second structural schematic diagram of a driving circuit provided in an embodiment of the present application.

[0081] Combine Figure 4 As shown, the driving circuit 101 provided in the embodiment of the present application may include: a voltage regulator diode D1, a capacitor C1, and a fifth resistor R5.

[0082] Among them, the first end of the voltage regulator D1 is connected to the first end of the fifth resistor R5, the second end of the voltage regulator D1 is connected to the positive electrode of the designated port, the second end of the fifth resistor R5 is connected to the first end of the capacitor C1 and the first end of the switching circuit 102, and the second end of the capacitor C1 is connected to the negative electrode of the designated port.

[0083] The positive pole of the designated port is Figure 4 The Vo+ shown in the figure specifies the negative terminal of the port. Figure 4 Vo- shown in .

[0084] The fifth resistor R5 can limit the current flowing through the Zener diode D1 and the switch circuit 102, preventing damage to the Zener diode D1 due to excessive current. Furthermore, the fifth resistor R5 and the Zener diode D1 are connected in series, and together they act as a voltage divider, ensuring that the voltage across the Zener diode D1 is within its normal operating range.

[0085] It should be understood that when there is a voltage on Vo+, the input voltage at the second end of the Zener diode D1 is the voltage of Vo+. When the voltage of Vo+ is greater than the stable voltage value of the Zener diode D1, the Zener diode D1 is broken down, so that the voltages at the first and second ends of the Zener diode D1 are equal. At this time, the Zener diode D1 can drive the switch circuit 102 to connect the second and third ends of the switch circuit 102, thereby short-circuiting the input or output end of the power conversion device to protect the device.

[0086] See also Figure 5 , this figure is a third structural schematic diagram of a driving circuit provided in an embodiment of the present application.

[0087] Combine Figure 5 As shown, the driving circuit 101 provided in the embodiment of the present application may include: a voltage regulator tube D1, a capacitor C1, a sixth resistor R6 and a diode D3.

[0088] The first end of the voltage-stabilizing diode D1 is connected to the first end of the sixth resistor R6 and the first end of the diode D3, the second end of the voltage-stabilizing diode D1 is connected to the positive electrode of the designated port, the second end of the diode D3 is connected to the first end of the switching circuit 102, the first end of the capacitor C1 is connected to the first end of the diode, and the second end of the capacitor C1 is connected to the second end of the sixth resistor R6 and the negative electrode of the designated port.

[0089] The positive pole of the designated port is Figure 5 The Vo+ shown in the figure specifies the negative terminal of the port. Figure 5 Vo- shown in .

[0090] It should be understood that when there is a voltage on Vo+, the input voltage at the second end of the Zener diode D1 is the voltage of Vo+. When the voltage of Vo+ is greater than the stable voltage value of the Zener diode D1, the Zener diode D1 is broken down, so that the voltages at the first and second ends of the Zener diode D1 are equal. At this time, the Zener diode D1 can drive the switch circuit 102 to connect the second and third ends of the switch circuit 102, thereby short-circuiting the input or output end of the power conversion device to protect the device.

[0091] It should be noted that when the switching circuit 102 is a thyristor, under certain voltage conditions, the gate of the thyristor can be turned on as long as there is a trigger pulse. After the trigger pulse disappears, the thyristor can still maintain the on state and will only be turned off when the input current is less than the holding current of the thyristor. It can be used as a protection circuit when there is no stable power supply, and can alleviate the problem of only hiccup protection when the switching circuit 102 is a MOS tube.

[0092] As an example, when the switch circuit 102 is a thyristor, when a voltage appears on Vo+, the high-resistance resistors R2 and R5 drive the second switch device Q2 to conduct, and then the first switch device Q1 is turned on. The smaller resistance current-limiting resistor R4 is used to amplify the driving current. The voltage drop across resistor R4 is very small, so the voltage at the second end of D1 is approximately equal to Vo+. When the voltage of Vo+ is greater than the stable voltage value of the voltage-stabilizing diode D1, the voltage-stabilizing diode D1 breaks down, driving the thyristor to conduct, so that the thyristor conducts to achieve short-circuit protection. After achieving short-circuit protection, even if the voltage of Vo+ is pulled down, as long as a certain current exists, the second switch device Q2 can continue to maintain conduction protection until the energy current at the output terminal is too low to maintain the thyristor conduction. The second switch device Q2 returns to the off state, and the hiccup frequency is significantly reduced.

[0093] Based on the overvoltage protection circuit provided in the above embodiment, in one possible implementation, the power conversion device includes an input end and an output end; the input end and the output end are bidirectionally conductive, and the designated port includes the input end or the output end; or, the output end is unidirectionally conductive to the input end, and the designated port includes the output end.

[0094] Bidirectional energy conduction means that energy can flow from the input to the output, and vice versa. Examples of bidirectional energy conduction power conversion devices include circuit breakers, step-down circuits, and the like. Unidirectional energy conduction means that energy can flow from the input to the output, but not from the output. Examples of unidirectional energy conduction power conversion devices include step-up / step-down circuits, and the like.

[0095] It should be understood that if the energy at the input and output ends of the power conversion device is bidirectionally conductive, when the power conversion device is working normally, energy can flow from the input end to the output end; when the input end of the power conversion device is open, the voltage at the output end may be fed back to the input end, thereby causing overvoltage damage to the power conversion device. Therefore, the drive circuit and the switching circuit can be set at the input and / or output end of the power conversion device to protect the power conversion device.

[0096] It should be understood that if the power conversion device conducts energy unidirectionally from the output end to the input end, when the power conversion device is operating normally, energy flows from the input end to the output end; when the input end of the power conversion device is open, the voltage at the output end will not be fed back to the input end, but this may cause voltage accumulation at the output end of the power conversion device, thereby causing overvoltage damage to the power conversion device. Therefore, in order to avoid voltage accumulation at the output end, it is necessary to set the drive circuit and switch circuit at the output end of the power conversion device to protect the power conversion device. It should be noted that if the drive circuit and switch circuit are set at the input end of the power conversion device, because the power conversion device does not include a path from the output end to the input end, even if the second and third terminals of the switch circuit are connected, a temporary current loop cannot be formed, and thus protection of the power conversion device cannot be achieved.

[0097] Based on the overvoltage protection circuit provided in the above embodiment, in different application scenarios, the combination setting method of the driving circuit 101 and the switching circuit 102 varies. The following describes in detail the setting method of the overvoltage protection circuit in different application scenarios with reference to the accompanying drawings.

[0098] See also Figure 6 , which is a first schematic diagram of a protection circuit connection method provided by an embodiment of the present application. Figure 6 As shown, when the power conversion device is a step-down circuit (such as Figure 6 a and Figure 6 b) or a circuit breaker circuit (e.g. Figure 6 c and Figure 6 d), the overvoltage protection circuit 100 (including the drive circuit 101 and the switch circuit 102) can be connected to the input end of the step-down circuit (such as Figure 6 a in the figure) or the output terminal (as shown in Figure 6 The overvoltage protection circuit 100 (including the drive circuit 101 and the switch circuit 102) can be connected to the input end of the shutdown circuit (as shown in b); Figure 6 c in the figure) or the output terminal (as shown in Figure 6 d in the figure).

[0099] A step-down circuit (also known as a buck circuit) is a DC-DC converter based on the principle of inductive energy storage. It is also known as a step-down converter or step-down chopper circuit. It uses a switching element (usually a power MOSFET), an energy storage element (usually an inductor), and other electronic components to change the current flow in the circuit by periodically opening and closing the switching element, thereby converting a higher input voltage to a lower output voltage.

[0100] A circuit breaker is a circuit used to control the switching of circuits and protect electrical equipment. Its main function is to quickly cut off the circuit when a system failure occurs to protect equipment and personal safety.

[0101] See also Figure 7 , which is a second schematic diagram of a protection circuit connection method provided by an embodiment of the present application. Figure 7 As shown, when the power conversion device is a boost-buck circuit, the overvoltage protection circuit 100 (including the drive circuit 101 and the switch circuit 102) can be connected to the output end of the boost-buck circuit.

[0102] A step-up / step-down circuit (also known as a buck-boost circuit) is a circuit used to regulate power supply voltage. It combines the functions of a boost circuit and a buck circuit to adjust the voltage from one level to another. This circuit typically includes a transformer and electronic components to meet the voltage requirements of different devices. A boost circuit primarily increases the input power voltage to the desired output voltage level. A common step-up circuit is a boost circuit. This circuit utilizes components such as a switching transistor, an inductor, an output filter capacitor, and a load. By continuously switching the switch on and off, it increases the input voltage until the desired output voltage is reached. A step-down circuit, on the other hand, steps down the input power voltage to the desired output voltage level. A common step-down circuit is a buck circuit, which also includes components such as a switching transistor, an inductor, an output filter capacitor, and a load. The output voltage can be controlled by adjusting the ratio of the switching transistor on and off.

[0103] It should be noted that, for the Buck-Boost circuit, since the feedback voltage at the output end cannot be directly fed back to the input end through the body diode of the fourth switch device S4, it is not suitable to be set at the input end.

[0104] Based on the configuration of the overvoltage protection circuit 100 provided in the above embodiment, in some possible implementations, to save hardware costs, the power conversion device may be a DC-DC converter (DCDC circuit), and the switching device in the switch circuit 102 is the main power device in the DC-DC converter. The DC-DC converter includes any of the following: a step-down circuit, a boost-buck circuit, or a circuit breaker.

[0105] Direct current to direct current (DCDC) circuits are a branch of switching power supply technology. DCDC circuits convert a DC power source into DC power of varying voltages. Specifically, DCDC circuits control the on and off switching of switches to convert the input DC voltage into the desired DC output voltage. During this process, components such as inductors and capacitors in the DCDC circuits perform energy storage and filtering to ensure output voltage stability and minimize ripple.

[0106] The main power device refers to the device used to realize the key functions of the DC-DC conversion circuit. For example, in the step-down circuit, the main power device is usually a switching tube (such as a MOSFET tube, a bipolar junction transistor (BJT) tube), which controls the flow and conversion of electric energy by periodically turning on and off, thereby reducing the voltage. In the boost-buck circuit, the main power device is also a switching tube, which realizes the voltage step-up and step-down conversion by controlling the on and off of the switching tube and the charging and discharging process of energy storage elements such as inductors and capacitors. In the circuit breaker, the main power device may be a relay, MOSFET or other element with switching function.

[0107] In one possible implementation, the power conversion device includes a first switching device, wherein a first end of the first switching device is connected to the positive electrode of a designated port, and a second end of the first switching device is connected to the negative electrode of the designated port. It should be understood that to save hardware costs, the first switching device connected between the positive and negative electrodes of the designated port of the power conversion device can be used instead of the switch circuit 102 in this application.

[0108] Combine Figure 8 As shown, when the power conversion device is a buck circuit or a shutdown circuit, the switch device in the switch circuit 102 can be the first switch device S1 in the buck circuit (or shutdown circuit), and the drive circuit 101 can be set as shown in FIG. Figure 8 The input end of the step-down circuit shown in a (or set at Figure 8 The input terminal of the shut-off circuit shown in c in FIG), or the driving circuit 101 can be set as shown in FIG. Figure 8 The output terminal of the step-down circuit shown in b (or set as shown in Figure 8 The output end of the circuit breaker circuit shown in d).

[0109] It should be noted that the energy of the input end and the output end of the power conversion device in the embodiment of the present application is bidirectionally conducted. Figure 8Taking a in the figure as an example, the power conversion device is a step-down circuit. The voltage at the input end of the step-down circuit can be output to the output end of the step-down circuit through the second switching device S2 and the inductor L1. If the input end of the step-down circuit is open at this time, the voltage at the output end of the step-down circuit can be output to the input end of the step-down circuit through the second switching device S2 and the inductor L1. That is, the voltage can be transmitted from the input end to the output end, and the voltage can be transmitted from the output end to the input end. This characteristic is bidirectional energy conduction.

[0110] It should be noted that when the drive circuit 101 is set at the input end of the power conversion device, the drive circuit 101 draws power from the input end of the power conversion device. When the feedback voltage passes through the body diode of the lateral MOS in the circuit topology of the device to the input end, the drive circuit 101 is powered and the drive switch circuit 102 is turned on to achieve a protection effect. This is equivalent to increasing the hysteresis loop, which can reduce the hiccup frequency.

[0111] As an example, Figure 8 Taking the driving circuit 101 shown in b as an example, which is set at the output end of the buck circuit, when the input end of the buck circuit is open, the voltage at the output end of the buck circuit may be fed back to the input end through the inductor L and the body diode of the second switching device S2. When the output end voltage exceeds the maximum voltage allowed by the driving circuit 101, the driving circuit 101 will drive the first switching device S1 to turn on. The first switching device S1 can short-circuit the input end of the buck circuit, thereby forming a temporary current loop to avoid continuous voltage accumulation and protect the equipment.

[0112] In one possible implementation, in order to save hardware costs, the power conversion device may include a third switching device and a fourth switching device, the first end of the third switching device is connected to the positive pole of the output end of the power conversion device, the second end of the third switching device is connected to the negative pole of the output end of the power conversion device, the first end of the fourth switching device is connected to the positive pole of the output end of the power conversion device, and the second end of the fourth switching device is connected to the first end of the third switching device.

[0113] Combine Figure 9 As shown, when the power conversion device is a boost-buck circuit, the switching devices in the switch circuit 102 can be the third switching device S3 and the fourth switching device S4 in the boost-buck circuit, and the drive circuit 101 can be set at the output end of the boost-buck circuit.

[0114] It should be understood that when the input end of the boost-buck circuit is open, the voltage at the output end of the boost-buck circuit may accumulate rapidly. When the output end voltage exceeds the maximum voltage allowed by the drive circuit 101, the drive circuit 101 will drive the third switch device S3 and the fourth switch device S4 to turn on. The third switch device S3 and the fourth switch device S4 can short-circuit the output end of the boost-buck circuit, thereby forming a temporary current loop to avoid continuous voltage accumulation and protect the equipment.

[0115] It should be noted that the energy between the input and output ends of the power conversion device in the embodiment of the present application is unidirectionally conducted. Figure 9 For example, the power conversion device is a boost-buck circuit. The voltage at the input of the boost-buck circuit can be output to the output of the boost-buck circuit via the inductor L1 and the body diode of the fourth switch device S4. If the input of the boost-buck circuit is open, the voltage at the output of the boost-buck circuit cannot be output to the input of the boost-buck circuit via the fourth switch device S4 and the inductor L1. In other words, the voltage can flow from the input to the output, but not from the output to the input, which is a unidirectional energy conduction characteristic.

[0116] It should be understood that in the embodiment of the present application, by using the main power device of the DC-DC circuit as the switching device in the switching circuit of the overvoltage protection circuit, hardware costs can be saved while protecting the equipment.

[0117] Based on the overvoltage protection circuit 101 provided in the above embodiment, an embodiment of the present application further provides an optimizer, which includes the overvoltage protection circuit as described in any of the above embodiments.

[0118] Based on the overvoltage protection circuit provided in the above embodiments, an embodiment of the present application further provides a circuit breaker, which includes the overvoltage protection circuit as described in any of the above embodiments.

[0119] Based on the overvoltage protection circuit provided in the above embodiment, combined with Figure 10 As shown, an embodiment of the present application further provides a photovoltaic system 1000, comprising at least one optimizer 1001 and at least one inverter 1002;

[0120] The output end of each optimizer 1001 is connected to the input end of the corresponding inverter 1002; the input end of the optimizer 1001 is connected to the output end of the corresponding photovoltaic module; the optimizer 1001 is the optimizer described in any of the above embodiments.

[0121] The inverter 1002 is used to receive the DC power output by the corresponding optimizer 1001 and invert the DC power into AC power to supply power to the load.

[0122] The inverter is the core device of a photovoltaic system. Its primary function is to convert the DC power output from the optimizer into AC power suitable for the grid. In some implementations, the inverter also monitors parameters such as current, voltage, and frequency in the solar photovoltaic system and adjusts them according to system requirements to ensure normal operation.

[0123] It should be noted that the output terminals of the optimizers are connected in series as the output terminals, which are then connected to the corresponding inverters. There is no limit on the number of optimizers, nor on whether the optimizers and inverters are connected in a one-to-one or many-to-one relationship. Any connection between optimizers and inverters in photovoltaic systems known in the art falls within the scope of protection of the present invention.

[0124] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments.

[0125] The "first" and "second" (if any) in the names mentioned in the embodiments of this application are only used as name identifiers and do not represent the first or second in order.

[0126] The above is merely one specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. An overvoltage protection circuit, characterized in that: include: Driving circuit and switching circuit; The drive circuit is connected to a first end of the switch circuit; the drive circuit is configured to be connected in parallel to a designated port of a power conversion device to be protected; a second end of the switch circuit is connected to a positive electrode of the designated port of the power conversion device, and a third end of the switch circuit is connected to a negative electrode of the designated port of the power conversion device, wherein the designated port is at least one of an input end or an output end of the power conversion device; The driving circuit is configured to drive the second end and the third end of the switch circuit to be conductive in response to the voltage of the designated port being greater than a preset voltage threshold, wherein the preset voltage threshold is greater than a normal operating voltage of the designated port.

2. The overvoltage protection circuit according to claim 1, wherein: The driving circuit includes a Zener diode and a capacitor, the first end of the Zener diode is connected to the first end of the switching circuit, the second end of the Zener diode is connected to the positive electrode of the designated port, the first end of the Zener diode is connected to the first end of the capacitor, and the second end of the capacitor is connected to the negative electrode of the designated port.

3. The overvoltage protection circuit according to claim 2, characterized in that: The driving circuit further includes a first resistor, a second resistor, a third resistor, a fourth resistor, a second voltage regulator tube, a first switching device and a second switching device; Among them, the first end of the first resistor is connected to the second end of the second resistor and the first end of the first switching device, the second end of the first resistor is connected to the positive electrode of the designated port, the first end of the second resistor is connected to the third end of the second switching device, the first end of the third resistor is connected to the second end of the fourth resistor and the first end of the voltage regulator tube, the second end of the third resistor is connected to the third end of the first switching device, the first end of the fourth resistor is connected to the first end of the second switching device and the first end of the capacitor, the second end of the first switching device is connected to the second end of the voltage regulator tube and the positive electrode of the designated port, the second end of the second switching device is connected to the second end of the capacitor, the second end of the capacitor is connected to the second end of the second voltage regulator tube and the negative electrode of the designated port, and the first end of the voltage regulator tube is connected to the second end of the second voltage regulator tube and the first end of the switching circuit.

4. The overvoltage protection circuit according to claim 2, wherein: The driving circuit further includes: a fifth resistor; Among them, the first end of the voltage regulator is connected to the first end of the fifth resistor, the second end of the voltage regulator is connected to the positive electrode of the designated port, the second end of the fifth resistor is connected to the first end of the capacitor and the first end of the switching circuit, and the second end of the capacitor is connected to the negative electrode of the designated port.

5. The overvoltage protection circuit according to claim 2, wherein: The driving circuit further includes: a sixth resistor and a diode; The first end of the voltage-stabilizing diode is connected to the first end of the sixth resistor and the first end of the diode, the second end of the voltage-stabilizing diode is connected to the positive electrode of the designated port, the second end of the diode is connected to the first end of the switching circuit, the first end of the capacitor is connected to the first end of the diode, and the second end of the capacitor is connected to the second end of the sixth resistor and the negative electrode of the designated port.

6. The overvoltage protection circuit according to any one of claims 1 to 5, characterized in that: The power conversion device is a DC-DC circuit, the switching device in the switching circuit is the main power device in the DC-DC circuit, and the DC-DC circuit includes any one of the following: a step-down circuit, a boost-buck circuit or a circuit breaker.

7. The overvoltage protection circuit according to any one of claims 1 to 5, characterized in that: The power conversion device includes an input end and an output end; The input end and the output end are bidirectionally conductive, and the designated port includes the input end or the output end; or Energy is unidirectionally conducted from the output end to the input end, and the designated port includes the output end.

8. The overvoltage protection circuit according to any one of claims 1 to 5, characterized in that: The designated port includes a first designated port and a second designated port, and the drive circuit is configured to be connected in parallel to the first designated port; the second end of the switching circuit is connected to the positive pole of the second designated port, and the third end of the switching circuit is connected to the negative pole of the second designated port, the first designated port is at least one of the input end or the output end of the power conversion device, and the second designated port is at least one of the input end or the output end of the power conversion device.

9. The overvoltage protection circuit according to any one of claims 1 to 5, characterized in that: The power conversion device includes a first switching device, a first end of the first switching device is connected to the positive electrode of the designated port, and a second end of the first switching device is connected to the negative electrode of the designated port.

10. The overvoltage protection circuit according to any one of claims 1 to 5, characterized in that: The power conversion device includes a third switching device and a fourth switching device, the first end of the third switching device is connected to the positive pole of the output end of the power conversion device, the second end of the third switching device is connected to the negative pole of the output end of the power conversion device, the first end of the fourth switching device is connected to the positive pole of the output end of the power conversion device, and the second end of the fourth switching device is connected to the first end of the third switching device.

11. An optimizer, characterized in that: The optimizer includes the overvoltage protection circuit according to any one of claims 1-10.

12. A circuit breaker, characterized in that: The shutdown device comprises the overvoltage protection circuit according to any one of claims 1 to 10.

13. A photovoltaic system, characterized in that: The system includes at least one optimizer and at least one inverter; The output end of the optimizer is connected to the input end of the corresponding inverter; the input end of the optimizer is connected to the output end of the corresponding photovoltaic module; the optimizer includes the overvoltage protection circuit as described in any one of claims 1 to 10; the inverter is used to receive the direct current output by the corresponding optimizer, and invert the direct current into alternating current to power the load.

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