Protection circuit and related device

Abstract

The invention discloses a protection circuit and a related device, the protection circuit is installed in an electrical device, the protection circuit is connected in parallel with a first end of the electrical device, the first end is a voltage input end and / or a voltage output end of the electrical device, and the protection circuit is conducted when the voltage input end is in an open circuit, or is connected in parallel with the first end when the voltage output end is in an open circuit. The protection circuit is switched on when the voltage of the first end of the electrical equipment is greater than a preset voltage. Therefore, when a high voltage exists at the voltage input end or the voltage output end of the electrical equipment, the protection circuit arranged at the voltage input end or the voltage output end can be switched on so as to short-circuit the voltage input end or the voltage output end, and because the voltage input end or the voltage output end is short-circuited, a temporary current loop can be formed at the moment; therefore, current can circulate, accumulation of voltage and generation of a high-voltage state are avoided, electrical equipment is prevented from being damaged by high voltage, and the purpose of protecting the electrical equipment is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, and in particular to a protection circuit and related device. BACKGROUND

[0002] At present, during normal use of an electrical device, the input end of the electrical device may be open-circuited due to various factors, and thus may cause overvoltage damage to the electrical device under certain working conditions. Taking an optimizer in a photovoltaic system as an example, the input end of the optimizer may be open-circuited due to problems such as loose interface, human disassembly, and photovoltaic panel failure during use of the optimizer. If the current working condition is that the voltage of an inverter or another string in parallel circulation, the energy at the output end of the optimizer may flow back to the input end, that is, the energy flowing back at the output end may generate a high voltage, thereby causing overvoltage damage to the optimizer. SUMMARY

[0003] Based on the above problems, the present application provides a protection circuit and related device to solve the problem that the voltage input end or voltage output end of an electrical device is damaged due to a high voltage under certain working conditions.

[0004] Embodiments of the present application disclose the following technical solutions:

[0005] In a first aspect, the embodiments of the present application provide a protection circuit, which is installed in an electrical device; the protection circuit is connected in parallel to a first end of the electrical device; the first end of the electrical device is a voltage input end and / or a voltage output end of the electrical device.

[0006] The protection circuit is turned on when the voltage input end is open-circuited, or the protection circuit is turned on when the voltage at the first end of the electrical device is greater than a preset voltage.

[0007] Optionally, the protection circuit further comprises a controller; an auxiliary power supply of the controller is provided by the voltage input end.

[0008] The controller is configured to control the protection circuit to be disconnected when the voltage at the voltage input end is not zero.

[0009] Alternatively, the controller is configured to control the protection circuit to be turned on when the voltage at the voltage input end of the electrical device is not zero and the voltage at the voltage output end is greater than a preset voltage.

[0010] Alternatively, the controller is configured to control the protection circuit to be turned on when the voltage at the voltage input end of the electrical device is greater than a preset voltage.

[0011] Optionally, the protection circuit comprises a driving circuit and a switching circuit; the driving circuit is connected with the first end of the switching circuit; the driving circuit is configured to be connected in parallel with the first end of the electrical equipment to be protected; the second end of the switching circuit is connected with the positive pole of the first end of the electrical equipment, and the third end of the switching circuit is connected with the negative pole of the first end of the electrical equipment.

[0012] The driving circuit is configured to drive the second end and the third end of the switching circuit to be conductive in response to the voltage of the first end of the electrical equipment being greater than a preset voltage threshold, wherein the preset voltage threshold is greater than the normal working voltage of the first end of the electrical equipment.

[0013] Optionally, the driving circuit comprises a voltage stabilizing tube and a capacitor; the first end of the voltage stabilizing tube is connected with the first end of the switching circuit; the second end of the voltage stabilizing tube is connected with the positive pole of the first end of the electrical equipment; the first end of the voltage stabilizing tube is connected with the first end of the capacitor; and the second end of the capacitor is connected with the negative pole of the first end of the electrical equipment.

[0014] Optionally, the driving circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a second voltage stabilizing tube, a first switching device and a second switching device.

[0015] The first end of the first resistor is connected with 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 with the positive pole of the first end of the electrical equipment; the first end of the second resistor is connected with the third end of the second switching device; the first end of the third resistor is connected with the second end of the fourth resistor and the first end of the voltage stabilizing tube; the second end of the third resistor is connected with the third end of the first switching device; the first end of the fourth resistor is connected with 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 with the second end of the voltage stabilizing tube and the positive pole of the first end of the electrical equipment; the second end of the second switching device is connected with the second end of the capacitor; the second end of the capacitor is connected with the second end of the second voltage stabilizing tube and the negative pole of the first end of the electrical equipment; and the first end of the voltage stabilizing tube is connected with the second end of the second voltage stabilizing tube and the first end of the switching circuit.

[0016] Optionally, the driving circuit further comprises a fifth resistor.

[0017] The first end of the voltage stabilizing tube is connected with the first end of the fifth resistor; the second end of the voltage stabilizing tube is connected with the positive pole of the first end of the electrical equipment; the second end of the fifth resistor is connected with the first end of the capacitor and the first end of the switching circuit; and the second end of the capacitor is connected with the negative pole of the first end of the electrical equipment.

[0018] Optionally, the driving circuit further comprises a sixth resistor and a diode.

[0019] The first end of the Zener diode is connected to the first end of the sixth resistor and the first end of the diode. The second end of the Zener diode is connected to the positive terminal of the first terminal of the electrical equipment. The second end of the diode is connected to the first terminal of the switching circuit. The first end of the capacitor is connected to the first end of the diode. The second end of the capacitor is connected to the second end of the sixth resistor and the negative terminal of the first terminal of the electrical equipment.

[0020] Optionally, it also includes: a controller; the protection circuit includes a drive circuit and a switch circuit; the controller is connected to a first terminal of the drive circuit; a second terminal of the drive circuit is connected to a first terminal of the switch circuit; the second terminal of the switch circuit is connected to the positive terminal of the first terminal of the electrical equipment, and a third terminal of the switch circuit is connected to the negative terminal of the first terminal;

[0021] When the voltage at the first terminal of the electrical equipment is greater than the preset voltage threshold, the controller controls the drive circuit to turn on the second and third terminals of the switching circuit, wherein the preset voltage threshold is greater than the normal operating voltage at the first terminal of the electrical equipment.

[0022] Optionally, the driving circuit includes a seventh resistor, an eighth resistor, a ninth resistor, a third switching device, a fourth switching device, a fifth switching device, a Zener diode, a diode, and a second capacitor;

[0023] Among them, the first end of the seventh resistor is connected to the positive terminal of the first terminal of the electrical equipment; the second end of the seventh resistor is connected to the third terminal of the fifth switching device and the second terminal of the diode; the first and second ends of the eighth resistor are respectively connected to the third terminal of the third switching device and the first end of the ninth resistor; the common terminal of the eighth and ninth resistors is connected to the second terminal of the diode; the second end of the ninth resistor is connected to the first terminal of the fourth switching device and the first terminal of the second capacitor; the first end of the third switching device is connected to the positive terminal of the first terminal of the electrical equipment; the first end of the third switching device is also connected to the third terminal of the fourth switching device; the second end of the third switching device is connected to the positive terminal of the first terminal of the electrical equipment; the second end of the fourth switching device is connected to the second terminal of the second capacitor; the second end of the fifth switching device is connected to the negative terminal of the first terminal of the electrical equipment; the first end of the fifth switching device is connected to the output terminal of the controller; the first end of the Zener diode is connected to the first terminal of the switching circuit; the second end of the Zener diode is connected to the positive terminal of the first terminal of the electrical equipment; the first end of the diode is connected to the first end of the Zener diode; and the second capacitor is connected to the negative terminal of the first terminal of the electrical equipment.

[0024] Optionally, the driving circuit further includes: a tenth resistor, an eleventh resistor, a twelfth resistor, and a thirteenth resistor;

[0025] Among them, the first end of the tenth resistor is connected to the positive terminal of the first terminal of the electrical equipment, the second end of the tenth resistor is connected to the first terminal of the third switching device, the first end and the second end of the eleventh resistor are respectively connected to the first terminal of the third switching device and the third terminal of the fourth switching device, the first end and the second end of the twelfth resistor are respectively connected to the first terminal of the fifth switching device and the output terminal of the controller, the first end of the thirteenth resistor is connected to the first terminal of the fifth switching device, and the second end of the thirteenth resistor is connected to the negative terminal of the first terminal of the electrical equipment.

[0026] Optionally, when the protection circuit includes a switching circuit, the switching circuit is any one of the following: depletion-mode metal-oxide-semiconductor field-effect transistor (MOSFET), junction field-effect transistor (JFET), or gallium nitride high electron mobility transistor (GaN HEMT).

[0027] Optionally, the electrical equipment is a DC-to-DC circuit, and the switching device in the switching circuit is the main power device in the DC-to-DC circuit. The DC-to-DC circuit includes any of the following: a buck circuit, a boost-buck circuit, or a shutdown device.

[0028] Optionally, the electrical equipment includes a voltage input terminal and a voltage output terminal;

[0029] Energy conducts bidirectionally between the voltage input and voltage output terminals; the first terminal of the electrical equipment includes either a voltage input terminal or a voltage output terminal; or...

[0030] Energy conducts unidirectionally from the voltage output terminal to the voltage input terminal, and the first terminal of the electrical equipment includes the voltage output terminal.

[0031] Optionally, the switching circuit is a MOSFET or a thyristor.

[0032] Secondly, embodiments of this application provide an optimizer, which includes the protection circuit described in the first aspect.

[0033] Thirdly, embodiments of this application provide a shut-off device, which includes the protection circuit described in the first aspect.

[0034] Fourthly, embodiments of this application provide a photovoltaic system, the system including at least one optimizer and at least one inverter;

[0035] The optimizer's output is connected to the corresponding inverter's input; the optimizer's input is connected to the corresponding photovoltaic module's output; the optimizer includes the protection circuit described in the first aspect; the inverter receives the DC power output from the corresponding optimizer and converts the DC power into AC power to supply power to the load.

[0036] The protection circuit provided in this embodiment is installed inside the electrical equipment and connected in parallel to the first terminal of the electrical equipment. The first terminal is the voltage input terminal and / or voltage output terminal of the electrical equipment. The protection circuit conducts when the voltage input terminal is open-circuited, or when the voltage at the first terminal of the electrical equipment exceeds a preset voltage. Thus, when a high voltage exists at the voltage input or output terminal of the electrical equipment, the protection circuit installed at the voltage input or output terminal can be activated to short-circuit the voltage input or output terminal. Because the voltage input or output terminal is short-circuited, a temporary current loop is formed, allowing current to flow and preventing voltage accumulation and the generation of a high-voltage state. This prevents damage to the electrical equipment due to high voltage, thereby achieving the purpose of protecting the electrical equipment. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 A schematic diagram of a photovoltaic system provided for related technologies;

[0039] Figure 2 This is a first structural schematic diagram of a protection circuit provided in an embodiment of this application;

[0040] Figure 3 This is a schematic diagram of a second structure of a protection circuit provided in an embodiment of this application;

[0041] Figure 4 A third structural schematic diagram of a protection circuit provided in an embodiment of this application;

[0042] Figure 5 This is a first structural schematic diagram of a driving circuit provided in an embodiment of this application;

[0043] Figure 6 This is a schematic diagram of a second structure of a driving circuit provided in an embodiment of this application;

[0044] Figure 7 A third structural schematic diagram of a driving circuit provided in an embodiment of this application;

[0045] Figure 8 A fourth structural schematic diagram of a driving circuit provided in an embodiment of this application;

[0046] Figure 9A fourth structural schematic diagram of a protection circuit provided in an embodiment of this application;

[0047] Figure 10 A fifth structural schematic diagram of a driving circuit provided in an embodiment of this application;

[0048] Figure 11 A sixth structural schematic diagram of a driving circuit provided in an embodiment of this application;

[0049] Figure 12 This is a first schematic diagram of a protection circuit connection method provided in an embodiment of this application;

[0050] Figure 13 This is a second schematic diagram of a protection circuit connection method provided in an embodiment of this application;

[0051] Figure 14 A third schematic diagram illustrating a protection circuit connection method provided in an embodiment of this application;

[0052] Figure 15 A fourth schematic diagram illustrating a protection circuit connection method provided in an embodiment of this application;

[0053] Figure 16 This is a schematic diagram of a photovoltaic system provided in an embodiment of this application. Detailed Implementation

[0054] As described above, research on power electronic and electrical equipment has found that during normal use, the input terminal of the electrical equipment may become open-circuited due to various factors. When the electrical equipment is under certain operating conditions, the energy at the output terminal may flow back to the input terminal, resulting in overvoltage damage to the electrical equipment.

[0055] See Figure 1 Taking a photovoltaic scenario as an example, assume that the photovoltaic system 10 includes an inverter 11 and a photovoltaic string 12. The photovoltaic string 12 includes at least one optimizer 121 and at least one photovoltaic module 122. The input terminal of the optimizer 121 is connected to the output terminal of the corresponding photovoltaic module 122. The output terminals of each optimizer 121 are connected in series to serve as the output terminal of the photovoltaic string 12. The output terminal of the photovoltaic string 12 is connected to the input terminal of the inverter 11 through a DC bus. The photovoltaic string 12 is used to transmit DC power to the inverter 11 through the DC bus, and the inverter 11 is used to convert DC power into AC power to supply the grid.

[0056] As an example, based on the aforementioned photovoltaic scenario, when an open circuit occurs at the inverter's input, the inverter cannot obtain a stable input current or voltage. Internally, the open circuit may cause current instability or voltage abnormalities, resulting in arcing. The inverter will then trigger a blocking mechanism to cut off the output. During the blocking process, due to the sudden change in current, the PLC inductor and line parasitic inductance in the optimizer will generate a self-induced electromotive force. The effect of these inductances causes the EMI (electromagnetic interference) capacitor in the inverter to begin charging. As the EMI capacitor charges, the string voltage connected to it will gradually increase. When the voltage exceeds the string's rated voltage, an overvoltage phenomenon occurs. When the EMI capacitor is fully charged, its stored energy will flow back into the optimizer, further affecting the optimizer's voltage state. Before the auxiliary power source starts, the output may be subjected to a momentary high-voltage backflow current surge. This high-voltage backflow current will rapidly charge 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 that capacitor, the MOSFET may be damaged by overvoltage.

[0057] When the optimizer's input is open-circuited, inverter 12 blocks the waveform. In this case, inverter 11 does not operate. The PLC inductance and line parasitic inductance of optimizer 12 charge the EMI capacitor of inverter 11, causing string overvoltage. Then, the energy from the EMI capacitor flows back to the output of optimizer 12. The instantaneous high-voltage backflow current at the output quickly charges the output capacitor to overvoltage before the auxiliary power supply starts, leading to MOSFET overvoltage damage. Here, PLC inductance refers to the inductor used in PLC (Programmable Logic Controller) systems. Inductors are commonly used components in circuits, primarily storing electrical energy and impeding current changes. In PLC systems, inductors may be used for various purposes, such as power filtering, signal isolation, energy storage, and transfer. EMI (Electromagnetic Interference) capacitors, also known as EMI suppression capacitors or filter capacitors, are capacitors 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.

[0058] In another example, when the inverter stops, such as when the inverter's DC switch is turned off, the standby times of the two optimizers or shutdown devices are inconsistent. The string that switches to standby first (string A) is back-fed current by the other parallel string (string B). That is, for the optimizer with an open input (i.e., the optimizer in string A), since it no longer receives current from the power supply, it should be in a turned-off or standby state. However, due to the back-fed current, the optimizer's input terminal may be subjected to a voltage surge higher than its rated voltage. If this voltage exceeds the optimizer's rated voltage, it may cause damage to the internal components of the optimizer.

[0059] In other words, when the input terminal of an electrical device is open-circuited, the voltage at the output terminal will flow back to the input terminal. If the backflow voltage exceeds the rated voltage of the electrical device, it may cause damage to the electrical device.

[0060] To address the aforementioned problems, embodiments of this application provide a protection circuit and related device. The protection circuit is installed inside an electrical device and is connected in parallel to a first terminal of the electrical device, wherein the first terminal is the voltage input terminal and / or voltage output terminal of the electrical device. The protection circuit conducts when the voltage input terminal is open-circuited, or when the voltage at the first terminal of the electrical device exceeds a preset voltage.

[0061] Thus, when there is a high voltage at the voltage input or output terminal of an electrical device, the protection circuit installed at the voltage input or output terminal can be turned on to short-circuit the voltage input or output terminal. Since the voltage input or output terminal is short-circuited, a temporary current loop can be formed, allowing current to flow, thereby avoiding voltage accumulation and the generation of a high-voltage state, and thus preventing the electrical device from being damaged by high voltage, thereby achieving the purpose of protecting the electrical device.

[0062] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0063] See Figure 2 This figure is a schematic diagram of the first structure of a protection circuit provided in an embodiment of this application. Figure 2 a, b, and c in the diagram illustrate three different structures of the protection circuit. Figure 2 The number 'a' in the diagram shows that the protection circuit is set at the voltage input terminal; Figure 2 b in the diagram shows that the protection circuit is set at the voltage output terminal; Figure 2The 'c' in the diagram shows that the protection circuit is set at both the voltage input and voltage output terminals.

[0064] Combination Figure 2 As shown, the protection circuit 101 provided in this application embodiment is installed inside the electrical equipment. The protection circuit 101 is connected to the first terminal of the electrical equipment, which is the voltage input terminal IN and / or voltage output terminal OUT of the electrical equipment.

[0065] It should be noted that, since the protection circuit is installed inside the electrical equipment, for ease of explanation, the main circuit of the electrical equipment will be used as an example in the accompanying drawings of the following embodiments.

[0066] The voltage input terminal IN (or simply input terminal) is used to receive the external input voltage to the electrical equipment, and the voltage output terminal OUT (or simply output terminal) is used to output the operating voltage to power the electrical equipment or other equipment connected to it. The protection circuit 101 is activated when the external input voltage exceeds a preset voltage. The voltage input terminal IN can be used to receive the external input voltage received by the electrical equipment; this external input voltage is the voltage input to the electrical equipment.

[0067] Electrical equipment refers to the collective term for equipment such as generators, transformers, power lines, and circuit breakers in a power system. It encompasses all equipment related to the generation, transmission, distribution, and application of electrical energy. Electrical equipment is typically used to control, protect, and regulate the operation of circuits. In some possible implementations, electrical equipment can be inverters, relays, etc., or optimizers, shutdown devices, etc., without specific limitations here.

[0068] As an example, using an electrical device as an optimizer, assume a protection circuit is located at the optimizer's voltage output terminal. When the optimizer is operating normally, the protection circuit is open. If the optimizer's voltage input terminal becomes open due to cable damage, the voltage at the optimizer's input terminal drops from the operating voltage (the voltage during normal operation) to zero. Since other photovoltaic modules are still operating normally, their energy may flow back from the optimizer's voltage output terminal to the optimizer's voltage input terminal. At this point, the voltage at the optimizer's voltage input terminal will change from zero to a higher voltage (greater than the normal operating voltage), potentially causing overvoltage damage to the optimizer. The protection circuit provided in this embodiment can activate when the optimizer's voltage input terminal is determined to be open. The protection circuit and the voltage output terminal form a temporary current loop, preventing energy from flowing back to the optimizer's voltage input terminal, thus protecting the electrical device.

[0069] As another example, taking an electrical device as an optimizer for illustration, assume that the protection circuit is located at the voltage output terminal of the optimizer. When the optimizer is operating normally, the protection circuit is open. If, at this time, the inverter connected to the optimizer generates energy due to voltage blocking and this energy flows back to the voltage output terminal of the optimizer, then the voltage at the voltage output terminal will change from the operating voltage to a higher voltage (greater than the normal operating voltage). Furthermore, this energy may flow back to the voltage input terminal of the optimizer, potentially damaging the optimizer due to overvoltage. The protection circuit provided in this application embodiment can conduct when it determines that the voltage at the first terminal of the optimizer (i.e., the voltage input terminal or the voltage output terminal) exceeds a preset voltage, thereby forming a temporary current loop to prevent voltage accumulation and the generation of high voltage, thus achieving the purpose of protecting the electrical equipment.

[0070] In this embodiment, when the protection circuit is located at the voltage input terminal, when the voltage input terminal is open or the voltage at the voltage input terminal is zero, the protection circuit can be turned on to short-circuit the voltage input terminal, thereby protecting the electrical equipment. When the protection circuit is located at the voltage output terminal, when the voltage at the voltage output terminal is greater than a preset voltage, the protection circuit can be turned on to short-circuit the voltage output terminal, thereby protecting the electrical equipment. When the protection circuit is located at both the voltage input terminal and the voltage output terminal, when the voltage input terminal is open and the voltage is zero or a higher voltage is generated, or when a higher voltage is generated at the voltage output terminal, the protection circuit can be turned on to short-circuit the voltage input terminal and / or the voltage output terminal, thereby protecting the electrical equipment.

[0071] Based on the protection circuit provided in the above embodiments, see [link to relevant documentation]. Figure 3 This figure is a schematic diagram of a second structure of a protection circuit provided in an embodiment of this application. Figure 3 In Figure 'a', protection circuit 101 is set at the voltage input terminal; Figure 3 b in the diagram shows that the protection circuit 101 is set at the voltage output terminal; Figure 3 The 'c' in the diagram shows that the protection circuit 101 is set at both the voltage input and voltage output terminals.

[0072] Combination Figure 3 As shown, the electrical equipment provided in this application embodiment also includes a controller 201; the auxiliary power supply of the controller 101 is provided by the voltage input terminal of the electrical equipment.

[0073] The controller 201 is used to control the protection circuit 101 to disconnect when the voltage at the voltage input terminal IN is not zero; or, when the voltage input terminal IN of the electrical equipment is open, the controller does not output a control signal and the short-circuit circuit 202 is turned on; or, when the voltage at the voltage input terminal IN of the electrical equipment is not zero and the voltage at the voltage output terminal OUT is greater than a preset voltage, the controller is used to control the short-circuit circuit 202 to turn on; or, when the voltage at the voltage input terminal IN of the electrical equipment is greater than a preset voltage, the controller is used to control the short-circuit circuit 202 to turn on.

[0074] It should be noted that the electrical components that are the same as those in the embodiments of the present application and those in the above embodiments use the same reference numerals as those in the previous embodiments. For detailed explanations, please refer to the above embodiments, which will not be repeated here.

[0075] It should be understood that a controller refers to a unit used to realize voltage judgment and control, which can be an MCU (microcontroller unit). An MCU is also known as a single-chip microcomputer or microcontroller. It is an integrated circuit that integrates functions such as processor core, memory, input / output interface and timer into one unit.

[0076] It should be understood that, in the embodiments of this application, an additional controller can be added to control the protection circuit. The auxiliary power supply of the controller is provided by the voltage input terminal of the electrical equipment. When the electrical equipment is working normally, the controller detects that the voltages at both the voltage input terminal and the voltage output terminal are within the normal operating voltage range. At this time, in order to avoid the influence of the protection circuit on the electrical equipment, the controller needs to control the protection circuit to disconnect. When the voltage input terminal is open, the voltage at the voltage input terminal is zero. At this time, the auxiliary power supply of the controller has no voltage, and therefore the controller cannot control the protection circuit (if the protection circuit is a short circuit, the protection circuit is closed when the voltage at the voltage input terminal is zero; if the protection circuit is an open circuit, the protection circuit is disconnected when the voltage at the voltage input terminal is zero). When the reverse voltage at the voltage output terminal reaches the output terminal, the auxiliary power supply is powered on and started. After the controller starts, it controls the conduction and disconnection of the protection circuit according to the detection and judgment logic set in the software program (if the voltage at the voltage input terminal or the voltage output terminal is greater than the preset voltage, the protection circuit is controlled to be closed) to achieve short circuit protection.

[0077] See Figure 4 This figure is a schematic diagram of a third structure of a protection circuit provided in an embodiment of this application. Wherein, Figure 4 The number 'a' in the diagram shows that the protection circuit is set at the voltage input terminal; Figure 4 b in the diagram shows that the protection circuit is set at the voltage output terminal; Figure 4 The 'c' in the diagram shows that the protection circuit is set at both the voltage input and voltage output terminals.

[0078] Combination Figure 4 As shown, the protection circuit 101 provided in this embodiment may include a driving circuit 301 and a switching circuit 302. The driving circuit 301 is connected to the first terminal of the switching circuit 302, and the second and third terminals of the switching circuit 302 are respectively connected to the positive terminal IN+ and the negative terminal IN- of the voltage input terminal, or the second and third terminals of the switching circuit 302 are respectively connected to the positive terminal OUT+ and the negative terminal OUT- of the voltage output terminal.

[0079] It should be understood that when the switching circuit 302 is set at the voltage input terminal, the first and second terminals of the switching circuit 302 are respectively connected to the positive terminal IN+ and the negative terminal IN- of the voltage input terminal. Similarly, when the switching circuit 302 is set at the voltage output terminal, the first and second terminals of the switching circuit 302 are respectively connected to the positive terminal OUT+ and the negative terminal OUT- of the voltage output terminal.

[0080] It should be understood that the drive circuit 301 is configured to turn off the drive switch circuit 302 when the voltage at the voltage input terminal is not zero, or when the voltage at the first terminal is less than or equal to a preset voltage; it is also configured to turn on the drive switch circuit 302 when the voltage at the first terminal is greater than the preset voltage.

[0081] In this embodiment, when the voltage at the first terminal is greater than the preset voltage, the driving circuit 301 will drive the switching circuit 302 to conduct. When the protection circuit is set at the voltage input terminal, it can cause the voltage input terminal to be short-circuited; when the protection circuit is set at the voltage output terminal, it can cause the voltage output terminal to be short-circuited; when the protection circuit is set at both the voltage input terminal and the voltage output terminal, it can cause the voltage input terminal and the voltage output terminal to be short-circuited, so as to avoid damage caused by the generation of high voltage at the voltage input terminal and / or the voltage output terminal, thereby achieving the purpose of protecting electrical equipment.

[0082] It should be noted that in one possible implementation, the drive circuit 202 can also be powered from the voltage input terminal. When the reverse voltage passes through the body diode of the transverse MOS in the circuit topology of the electrical equipment to the voltage input terminal, the drive circuit 202 is powered, and the drive switch circuit 302 is turned on to achieve the protection effect. This is equivalent to adding hysteresis, which can reduce the hiccup frequency.

[0083] It should be noted that, in one possible implementation, the drive circuit 202 is configured to be connected in parallel to the first port; the second terminal of the switch circuit 302 is connected to the positive terminal of the second first terminal, and the third terminal of the switch circuit 302 is connected to the negative terminal of the second first terminal. The first first terminal is at least one of the input terminal or output terminal of the main circuit of the electrical equipment, and the second first terminal is at least one of the input terminal or output terminal of the main circuit of the electrical equipment.

[0084] It should be understood that the drive circuit 202 can be set at the voltage input terminal, voltage output terminal, voltage input terminal, and voltage output terminal of the main circuit of the electrical equipment. Similarly, the switch circuit 302 can be set at the voltage input terminal, voltage output terminal, voltage input terminal, and voltage output terminal of the main circuit of the electrical equipment. The combination of drive circuit 202 and switch circuit 302 can include various configurations. Different combination configurations can be used for different main circuits of different electrical equipment. The following will illustrate the combination configurations of drive circuit 202 and switch circuit 302 with specific examples, and will not be elaborated further here.

[0085] See Figure 5 The figure is a schematic diagram of the first structure of a driving circuit provided in an embodiment of this application.

[0086] Combination Figure 5 As shown, the driving circuit 301 provided in this embodiment may include a Zener diode D1 and a capacitor C1. The first end of the Zener diode D1 is connected to the first end of the switching circuit 302, and the second end of the Zener diode D1 is connected to the positive terminal of the first terminal of the electrical device (i.e., Figure 5 As shown in the diagram (Vo+), the first terminal of the Zener diode D1 is connected to the first terminal of capacitor C1, and the second terminal of capacitor C1 is connected to the negative terminal of the first terminal of the electrical device (i.e., Figure 5 The Vo- mentioned in the text.

[0087] A Zener diode, also known as a voltage regulator, electronic voltage regulator, or Zener diode, is a semiconductor device that automatically adjusts the resistance value in a circuit to maintain a constant output voltage. A Zener diode has a stable breakdown voltage. When the reverse voltage exceeds this breakdown voltage, the Zener diode enters a breakdown state, but its voltage will remain at the breakdown voltage value, thus maintaining a constant voltage in the circuit. Under forward operating voltage, a Zener diode behaves like a diode, conducting normally; however, when the reverse voltage exceeds its breakdown voltage, it exhibits voltage regulation characteristics.

[0088] It should be noted that Zener diodes can also be replaced by devices that can achieve voltage regulation, such as transistor regulators, integrated circuit regulators, switching regulators, and linear regulators. However, from a cost perspective, Zener diodes are preferred.

[0089] It should be understood that this embodiment utilizes the PN junction structure and reverse breakdown voltage characteristics of a Zener diode. By setting a suitable stable voltage value, when the voltage input to the second terminal of Zener diode D1 (hereinafter referred to as the input voltage) is less than or equal to this stable voltage value, Zener diode D1 is not conducting, that is, the second and third terminals of the switching circuit 302 are not connected. When the input voltage at the second terminal of Zener diode D1 is greater than this stable voltage value, Zener diode D1 breaks down, making the voltages at the first and second terminals of Zener diode D1 equal. At this time, Zener diode D1 can drive the switching circuit 302 to connect the second and third terminals of the switching circuit 302. The stable voltage value of Zener diode D1 can be preset, and the specific setting method is not limited here.

[0090] It should be noted that when the input voltage exceeds the Zener diode's stable voltage, the Zener diode will begin to conduct and limit further voltage increases, thus acting as a clamp to limit the input voltage within a specific range. By limiting the input voltage within this range, the circuit can be effectively protected from damage caused by excessive voltage, ensuring its stability and reliability.

[0091] It should be noted that, since the voltage at the input or output terminal may suddenly rise after the input terminal of the electrical equipment is opened, in order to avoid damage to the drive circuit, capacitor C1 can absorb or release some energy, thereby slowing down the rate of voltage change and preventing voltage surges from damaging the switching circuit.

[0092] In this embodiment of the application, by utilizing the reverse breakdown characteristic of the Zener diode in the driving circuit, when the input voltage at the second terminal of the Zener diode is greater than the stable voltage value, that is, when the input or output terminal is open-circuited, the Zener diode D1 conducts, which in turn drives the switching circuit 302 to conduct, so as to short-circuit the input or output terminal of the electrical equipment, forming a temporary current loop to protect the equipment.

[0093] See Figure 6 The figure is a schematic diagram of the second structure of a driving circuit provided in an embodiment of this application.

[0094] Combination Figure 6 As shown, the driving circuit 301 includes a Zener diode D1, a capacitor C1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a second Zener diode D2, a first switching device Q1, and a second switching device Q2.

[0095] In this circuit, 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 terminal of the first terminal of the electrical device. 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 Zener 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 Zener diode D1 and the positive terminal of the first terminal of the electrical device. 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 Zener diode D2 and the negative terminal of the first terminal of the electrical device. The first end of the Zener diode D1 is connected to the second end of the second Zener diode D2 and the first terminal of the switching circuit 302.

[0096] Among them, the positive terminal of the first end of the electrical equipment is Figure 6 The Vo+ shown is the negative terminal of the first end of the electrical device. Figure 6 The Vo- shown.

[0097] It should be understood that, taking the protection circuit composed of drive circuit 301 and switch circuit 302 connected in parallel at the output terminal, with switch circuit 302 being a MOSFET as an example, when the voltage of Vo+ is higher than the stable voltage value of D1, the Zener diode D1 is broken down. At this time, the Zener diode D1 conducts, which in turn drives the second switching device Q2 to conduct through D1 and R4. Then the first switching device Q1 conducts, and the voltage of Vo+ reaches the first terminal of switch circuit 302 through current limiting resistor R3 to drive switch circuit 302 to conduct, thereby achieving the short circuit protection effect.

[0098] It should be noted that, in this embodiment, the stable voltage value of the Zener diode D1 needs to be greater than the rated output voltage of the electrical equipment to avoid affecting the normal operation of the electrical equipment. Furthermore, when the first switching device Q1 is turned on, the voltage Vo+ will reach the first terminal of the switching circuit 302 (e.g., the gate of the MOSFET) after passing through the first switching device Q1 and the current-limiting resistor R4. Since the voltage value of Vo+ is relatively high, and the voltage Vgs (the voltage difference between the gate and source) that the first terminal of the switching circuit 302 can withstand generally does not exceed 20V, protection is required through the second Zener diode D2. By adjusting the stable voltage value of the second Zener diode D2, damage to the switching circuit 302 due to Vgs overvoltage can be prevented.

[0099] It should be noted that if the switching circuit 302 is a MOSFET, when the driving circuit turns on the MOSFET, the MOSFET will pull down the voltage of Vo+. The MOSFET will then turn off due to the loss of its driving voltage, entering a hiccup protection state, but this still achieves the purpose of protecting the equipment. Furthermore, the stable voltage value of the Zener diode must be greater than or equal to the rated output voltage value of the electrical equipment; otherwise, it may affect the normal operation of the electrical equipment.

[0100] See Figure 7 The figure is a schematic diagram of the third structure of a driving circuit provided in an embodiment of this application.

[0101] Combination Figure 7 As shown, the driving circuit 301 includes a Zener diode D1, a capacitor C1, and a fifth resistor R5.

[0102] Among them, the first end of the Zener diode D1 is connected to the first end of the fifth resistor R5, the second end of the Zener diode D1 is connected to the positive terminal of the first terminal of the electrical equipment, the second end of the fifth resistor R5 is connected to the first end of the capacitor C1 and the first terminal of the switching circuit 302, and the second end of the capacitor C1 is connected to the negative terminal of the first terminal of the electrical equipment.

[0103] Among them, the positive terminal of the first end of the electrical equipment is Figure 7 The Vo+ shown is the negative terminal of the first end of the electrical device. Figure 7 The Vo- shown.

[0104] The fifth resistor, R5, limits the current flowing through the Zener diode D1 and the switching circuit 302, preventing damage to the Zener diode D1 due to excessive current. Furthermore, the fifth resistor R5, connected in series with the Zener diode D1, may work together to divide the voltage, ensuring that the voltage across the Zener diode D1 remains within its normal operating range.

[0105] It should be understood that when a voltage Vo+ appears, the input voltage at the second terminal 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, making the voltage at the first and second terminals of the Zener diode D1 equal. At this time, the Zener diode D1 can drive the switching circuit 302 to connect the second and third terminals of the switching circuit 302, thereby short-circuiting the input or output terminals of the electrical equipment to protect the equipment.

[0106] See Figure 8 The figure is a schematic diagram of the fourth structure of a driving circuit provided in an embodiment of this application.

[0107] Combination Figure 8 As shown, the driving circuit 301 includes a Zener diode D1, a capacitor C1, a sixth resistor R6, and a diode D3.

[0108] The first terminal of Zener diode D1 is connected to the first terminal of the sixth resistor R6 and the first terminal of diode D3. The second terminal of Zener diode D1 is connected to the positive terminal of the first terminal of the electrical equipment. The second terminal of diode D3 is connected to the first terminal of switch circuit 302. The first terminal of capacitor C1 is connected to the first terminal of diode. The second terminal of capacitor C1 is connected to the second terminal of the sixth resistor R6 and the negative terminal of the first terminal of the electrical equipment.

[0109] Among them, the positive terminal of the first end of the electrical equipment is Figure 8 The Vo+ shown is the negative terminal of the first end of the electrical device. Figure 8 The Vo- shown.

[0110] It should be understood that when a voltage Vo+ appears, the input voltage at the second terminal 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, making the voltage at the first and second terminals of the Zener diode D1 equal. At this time, the Zener diode D1 can drive the switching circuit 302 to connect the second and third terminals of the switching circuit 302, thereby short-circuiting the input or output terminals of the electrical equipment to protect the equipment.

[0111] It should be noted that when the switching circuit 302 is a thyristor, the thyristor can be turned on as long as there is a trigger pulse at the gate under certain voltage conditions. After the trigger pulse disappears, the thyristor can still maintain the conducting state. It will only turn off when the sink current is less than the holding current of the thyristor. It can be used for protection circuits when there is no stable power supply, which can alleviate the problem that the switching circuit 302 can only hiccup protection when it is a MOSFET.

[0112] As an example, when the switching circuit 302 is a thyristor, when a voltage Vo+ appears, the high-resistance resistors R2 and R5 drive the second switching device Q2 to conduct, and then the first switching device Q1 conducts. The smaller current-limiting resistor R4 amplifies the drive current. The voltage drop across resistor R4 is very small, so the voltage at the second terminal of D1 is almost equal to Vo+. When the voltage Vo+ exceeds the stable voltage of the Zener diode D1, D1 breaks down, driving the thyristor to conduct, thus achieving short-circuit protection. After short-circuit protection is achieved, even if the voltage Vo+ is pulled low, as long as a certain current exists, the second switching device Q2 can continue to conduct until the output current is too small to maintain the thyristor's conduction. At this point, the second switching device Q2 returns to the off state, and the hiccup frequency is significantly reduced.

[0113] Based on the protection circuit provided in the above embodiments, in one possible implementation, the electrical device includes an input terminal and an output terminal; the input terminal and the output terminal are bidirectionally connected, and the first terminal of the electrical device includes the input terminal or the output terminal; or, the output terminal and the input terminal are unidirectionally connected, and the first terminal of the electrical device includes the output terminal.

[0114] Bidirectional energy conduction means that energy in an electrical device can flow from the input to the output and from the output to the input. Examples of bidirectional energy conduction devices include circuit breakers, step-down circuits, etc. Unidirectional energy conduction means that energy in an electrical device can flow from the input to the output, but not from the output. Examples of unidirectional energy conduction devices include step-up / step-down circuits, etc.

[0115] It should be understood that if the input and output terminals of an electrical device are bidirectionally conductive, energy can flow from the input terminal to the output terminal during normal operation. However, when the input terminal of the electrical device is open-circuited, the voltage at the output terminal may flow back to the input terminal, potentially causing overvoltage damage to the electrical device. Therefore, drive circuits and switching circuits can be placed at the input and / or output terminals of the electrical device to protect it.

[0116] It should be understood that if an electrical device allows unidirectional energy flow from its output to its input, energy flows from the input to the output during normal operation. When the input is open, the voltage at the output will not flow back to the input, but voltage accumulation at the output may occur, potentially leading to overvoltage damage. Therefore, to prevent voltage accumulation at the output, the drive circuit and switching circuit must be located at the output of the device for protection. It should be noted that if the drive circuit and switching circuit are located at the input, since the device does not have a path from the output to the input, even if the second and third terminals of the switching circuit are connected, a temporary current loop cannot be formed, thus failing to protect the device.

[0117] See Figure 9 This figure is a schematic diagram of the fourth structure of a protection circuit provided in an embodiment of this application. Wherein, Figure 9 The number 'a' in the diagram shows that the protection circuit is set at the voltage input terminal; Figure 9 b in the diagram shows that the protection circuit is set at the voltage output terminal; Figure 9 The 'c' in the diagram shows that the protection circuit is set at both the voltage input and voltage output terminals.

[0118] Combination Figure 9As shown, the protection circuit 800 provided in this application embodiment may include: a protection circuit 101 and a controller 201; the protection circuit 101 includes a drive circuit 301 and a switch circuit 302; the drive circuit 301 is connected to the first terminal of the switch circuit 302; the second terminal and the third terminal of the switch circuit 302 are respectively connected to the positive and negative terminals of the voltage input terminal, or the second terminal and the third terminal of the switch circuit 302 are respectively connected to the positive and negative terminals of the voltage output terminal.

[0119] Specifically, when the voltage at the voltage input terminal or voltage output terminal is less than or equal to the preset voltage, the controller controls the drive circuit to disconnect, so that the switching circuit is open.

[0120] As an example, when the voltage input terminal is open, there is no power input, the MCU cannot work, and the switching circuit 302 is in the conducting state. In the event of reverse voltage or current, it can directly provide short-circuit protection. When the voltage input terminal is normal, and the voltage output terminal of the electrical equipment is normally connected to the photovoltaic panel, the MCU sends a signal after startup to directly or indirectly control the switching circuit 302 to disconnect, the protection function fails, and the electrical equipment can normally output voltage. In the startup state, during normal operation, the MCU continuously monitors the output voltage signal. If an abnormally high voltage is detected at the output terminal, the MCU immediately controls the electrical equipment to switch to standby mode, stops outputting voltage, and removes the drive signal for the switching circuit 302. The switching circuit 302 will automatically turn on for protection. Furthermore, the MCU software can be additionally configured with a recovery control scheme to allow the electrical equipment to resume normal operation after a period of time.

[0121] It should be noted that when the controller determines that the voltage at the voltage input or voltage output terminal is less than or equal to the preset voltage, it considers the circuit to be in normal working condition. At this time, the controller needs to control the drive circuit to disconnect, so that the drive circuit cannot send a drive signal to the switching circuit, thus making the switching circuit open. When the controller determines that the voltage at the voltage input or voltage output terminal is greater than the preset voltage, it considers that there is a fault at the input or output terminal of the circuit. At this time, the controller needs to control the drive circuit to send a drive signal to the switching circuit, so that the switching circuit is closed, thereby achieving a short circuit at the voltage input or voltage output terminal to protect the electrical equipment.

[0122] Based on the protection circuit provided in the above embodiments, to further illustrate the connection relationship between the controller 201, the drive circuit 301, and the switch circuit 302, please refer to... Figure 10 The figure is a schematic diagram of the fifth structure of a driving circuit provided in an embodiment of this application.

[0123] Combination Figure 10As shown, the driving circuit 301 provided in this application embodiment may include a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a third switching device Q3, a fourth switching device Q4, a fifth switching device Q5, a Zener diode D1, a diode D3, and a second capacitor C2.

[0124] In this circuit, the first terminal of the seventh resistor R7 is connected to the positive terminal of the optimizer's main circuit output. The second terminal of the seventh resistor R7 is connected to the third terminal of the fifth switching device Q5 and the second terminal of the diode D3. The first and second terminals of the eighth resistor R8 are respectively connected to the third terminal of the third switching device Q3 and the first terminal of the ninth resistor R9. The common terminal of the eighth resistor R8 and the ninth resistor R9 is also connected to the second terminal of the diode D3. The second terminal of the ninth resistor R9 is connected to the first terminal of the fourth switching device Q4 and the first terminal of the second capacitor C2. The first terminal of the third switching device Q3 is connected to the positive terminal of the optimizer's main circuit output. It is also connected to the third terminal of the fourth switching device Q4, the second terminal of the third switching device Q3 is connected to the positive terminal of the output terminal of the optimizer main circuit, the second terminal of the fourth switching device Q4 is connected to the second terminal of the second capacitor C2, the second terminal of the fifth switching device Q5 is connected to the negative terminal of the output terminal of the optimizer main circuit, the first terminal of the fifth switching device Q5 is connected to the output terminal of the controller 201, the first terminal of the Zener diode D1 is connected to the first terminal of the switching circuit 302, the second terminal of the Zener diode D1 is connected to the positive terminal of the output terminal of the optimizer main circuit, the first terminal of the diode D3 is connected to the first terminal of the Zener diode D1, and the second capacitor C2 is connected to the negative terminal of the output terminal of the optimizer main circuit.

[0125] It should be understood that, as Figure 13 The third switching device Q3 and the fourth switching device Q4 shown are transistors, used to provide sufficient current to drive the switching circuit 302 to conduct. Diode D3 is connected in series with the switching circuit 302, and its on-state voltage drop must be greater than 0.7V. The function of diode D3 is to raise the voltage across resistor R9 so that when the voltage Vo+ is greater than a preset voltage, current preferentially flows through R7 and R9, thereby turning on the fourth switching device Q4. Specifically, the driving circuit provided in this application embodiment performs different actions under three operating conditions, namely:

[0126] When the input terminal of the optimizer's main circuit is open, the electrical equipment cannot start. When a voltage (Vo+) flows back into the drive circuit, the current flows through R7 and R9 to turn on the fourth switching device Q4, which in turn turns on the third switching device Q3, thus enabling the drive circuit to operate. At this time, the current of Vo+ mainly flows sequentially through the third switching device Q3, the fourth resistor R8, and the diode D3 to reach the switching circuit 302, turning on the switching circuit 302 and thus providing overvoltage protection.

[0127] When the optimizer's main circuit input is properly connected, and a photovoltaic module is normally connected to the input, after the electrical equipment is powered on, the MCU will send a signal to pull the OVP_EN1 pin high, causing the fifth switching device Q5 to conduct and ground. The Vce of the fifth switching device Q5 is almost 0V, so the fourth switching device Q4 will not be turned on, and the switching circuit 302 will also not conduct. At this time, the normal output voltage Vo+ will only discharge through the seventh resistor R7 and the fifth switching device Q5. Choosing an appropriate value for the eighth resistor R8 can achieve lower losses.

[0128] When the input of the optimizer's main circuit is normal, but the output of the optimizer's main circuit experiences an abnormal overvoltage, the input of the optimizer's main circuit is not open-circuited, the machine operates normally, and the protection circuit cannot be activated. If, at this time, the output of the optimizer's main circuit exceeds the preset voltage, it will discharge through the Zener diode D1, driving the switching circuit 302 to conduct for short-circuit protection. The Zener voltage of the Zener diode D1 can be selected according to actual needs, and is generally greater than the rated output voltage of the electrical equipment.

[0129] The switching circuit 302 can be a thyristor, MOSFET, or other device. The diode D3 in the circuit can be a diode, a Zener diode, or a resistor, etc. The combination of these components should ensure that the driving switching circuit 302 is turned on.

[0130] See Figure 11 This figure is a sixth structural schematic diagram of a driving circuit provided in an embodiment of this application.

[0131] Combination Figure 11 As shown, the driving circuit 301 provided in this application embodiment may include a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a third switching device Q3, a fourth switching device Q4, a fifth switching device Q5, a Zener diode D1, a diode D3, a second capacitor C2, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a thirteenth resistor R13.

[0132] Specifically, the first end of the tenth resistor R10 is connected to the positive terminal of the output of the optimizer main circuit, the second end of the tenth resistor R10 is connected to the first terminal of the third switching device Q3, the first and second ends of the eleventh resistor R11 are connected to the first terminal of the third switching device Q3 and the third terminal of the fourth switching device Q4, respectively, the first and second ends of the twelfth resistor R12 are connected to the first terminal of the fifth switching device Q5 and the output of the controller 201, respectively, the first end of the thirteenth resistor R13 is connected to the first terminal of the fifth switching device Q5, and the second end of the thirteenth resistor R13 is connected to the negative terminal of the output of the optimizer main circuit.

[0133] Based on the protection circuit provided in the above embodiments, the switching circuit 302 can be any of the following: depletion-type metal-oxide-semiconductor field-effect transistor (MOSFET), junction field-effect transistor (JFET), or gallium nitride high electron mobility transistor (GaN HEMT).

[0134] It should be noted that the location of the protection circuits installed on different electrical devices may vary, that is, the connection relationship between different electrical devices and the protection circuit may be different. The same electrical device may also have multiple connection relationships with the protection circuit. Therefore, in the following embodiments, different connection methods are provided for three different electrical devices. However, the following connection methods are only examples and are not specifically limited here.

[0135] Furthermore, it should be noted that in some possible implementations, the protection circuit may include a drive circuit and a switching circuit. In another possible implementation, the drive circuit in the protection circuit may also be controlled by a controller (MCU). Therefore, although the connection relationship between the drive circuit and the controller in the protection circuit is not specifically described in the following embodiments, it can be understood that the output terminal of the controller is connected to the drive circuit to control the drive circuit.

[0136] Among them, Figures 12 to 14 The circuit shown illustrates the connection relationships between the drive circuit 301 and the switch circuit 302 in the protection circuit 101 and the electrical equipment, as well as the connection relationship between the controller 201 and the drive circuit 301. The switch circuit 302 can be an additional switch device or a switch device already in the circuit; no specific limitation is made here.

[0137] It should be noted that the location of the protection circuits installed on different electrical devices may vary, that is, the connection relationship between different electrical devices and the protection circuit may be different. The same electrical device may also have multiple connection relationships with the protection circuit. Therefore, in the following embodiments, different connection methods are provided for three different electrical devices. However, the following connection methods are only examples and are not specifically limited here.

[0138] Furthermore, it should be noted that in some possible implementations, the protection circuit may include a drive circuit and a switching circuit. In another possible implementation, the drive circuit in the protection circuit may also be controlled by a controller (MCU). Therefore, although the connection relationship between the drive circuit and the controller in the protection circuit is not specifically described in the following embodiments, it can be understood that the output terminal of the controller is connected to the drive circuit to control the drive circuit.

[0139] Based on the protection circuit provided in the above embodiments, the combination of the drive circuit 301 and the switch circuit 302 varies in different application scenarios. The following is a detailed description of the configuration of the protection circuit in different application scenarios with reference to the accompanying drawings.

[0140] See Figure 12 This figure is a first schematic diagram of a protection circuit connection method provided in an embodiment of this application. Combined with... Figure 12 As shown,

[0141] When the electrical equipment is a step-down circuit (such as...) Figure 12 a and Figure 12 (b) or the shutdown circuit (such as) Figure 12 c and Figure 12 In step d), the protection circuit 100 (including the drive circuit 301 and the switching circuit 302) can be connected to the input terminal of the step-down circuit (e.g., ...). Figure 12 (as shown in a) or output terminal (such as...) Figure 6 (as shown in b); the protection circuit 100 (including the drive circuit 301 and the switching circuit 302) can be connected to the input terminal of the shutdown circuit (as shown in b); Figure 6 (as shown in c) or output terminal (such as Figure 6 (as shown in d).

[0142] A buck converter (also known as a step-down converter or step-down chopper circuit) is a DC-DC converter based on the principle of inductor energy storage. It uses switching elements (usually power MOSFETs) and energy storage elements (usually inductors) and other electronic components to change the current flow in the circuit by periodically turning the switching elements on and off, thereby converting a higher input voltage into a lower output voltage.

[0143] A circuit breaker is a circuit used to control switching and protect electrical equipment. Its main function is to quickly disconnect the circuit when a system malfunctions, thereby protecting equipment and personal safety.

[0144] See Figure 13 This figure is a second schematic diagram of a protection circuit connection method provided in an embodiment of this application. Combined with... Figure 13 As shown, when the electrical equipment is a step-up / step-down circuit, the protection circuit 100 (including the drive circuit 301 and the switch circuit 302) can be connected to the output terminal of the step-up / step-down circuit.

[0145] A buck-boost circuit is a type of circuit used to regulate power supply voltage. It combines the functions of a boost circuit and a buck circuit, adjusting the voltage from one level to another. This type of circuit typically includes a transformer and electronic components to meet the voltage requirements of different devices. A boost circuit primarily increases the input voltage to the desired output voltage level. A common boost circuit is the boost converter, which uses components such as a switching transistor, inductor, output filter capacitor, and load to increase the input voltage by repeatedly switching the transistor on and off until the desired output voltage is reached. A buck converter, on the other hand, decreases the input voltage to the desired output voltage level. A common buck converter is the buck converter, which also includes components such as a switching transistor, inductor, output filter capacitor, and load. By adjusting the on / off time ratio of the switching transistor, the magnitude of the output voltage can be controlled.

[0146] It should be noted that, for Buck-Boost circuits, since the reverse voltage at the output cannot be directly reversed to the input through the body diode of the fourth switching device S4, it is not suitable to set it at the input.

[0147] Based on the configuration of the protection circuit 100 provided in the above embodiments, in some possible implementations, to save hardware costs, the electrical equipment can be a DC-DC converter (DCDC circuit), and the switching device in the switching circuit 302 can be the main power device in the DC-DC converter. The DC-DC converter includes any of the following: a buck converter, a boost-buck converter, or a shutdown device.

[0148] A DC-DC converter (DCDC) is a branch of switching power supply technology. A DCDC circuit converts a given DC power source into DC power at different voltage values. Specifically, the DCDC circuit controls the switching transistors to convert the input DC voltage into the desired DC output voltage. During this process, components such as inductors and capacitors in the DCDC circuit act as energy storage and filtering agents to ensure the stability and ripple level of the output voltage.

[0149] The term "main power device" refers to the device used to perform its key functions in a DC-DC converter. For example, in a buck converter, the main power device is usually a switching transistor (such as a MOSFET or a bipolar junction transistor, BJT). These transistors control the flow and conversion of electrical energy by periodically turning on and off, thereby reducing the voltage. In a boost-buck converter, the main power device is also a switching transistor. By controlling the switching on and off of the transistor, as well as the charging and discharging process of energy storage components such as inductors and capacitors, the voltage is converted from boost to buck. In a shutdown circuit, the main power device may be a relay, a MOSFET, or other components with switching functions.

[0150] In one possible implementation, the electrical device includes a first switching device, with a first terminal connected to the positive terminal of the first terminal and a second terminal connected to the negative terminal of the first terminal. It should be understood that, to save hardware costs, the first switching device connected between the positive and negative terminals of the first terminal of the electrical device can be used instead of the switching circuit 302 in this application. Here, "first terminal" refers to at least one of the voltage input or voltage output terminals of the electrical device.

[0151] See Figure 14 When the electrical equipment is a step-down circuit or a circuit breaker circuit, the switching device in the switching circuit 302 can be the first switching device S1 in the step-down circuit (or circuit breaker circuit), and the drive circuit 301 can be set as follows: Figure 14 The input terminal of the step-down circuit shown in Figure 'a' (or set at, for example, the input terminal of the step-down circuit) Figure 14 The input terminal of the shut-off circuit shown in c) or the drive circuit 301 can be set as follows: Figure 14 The output terminal of the step-down circuit shown in b (or set at, for example) Figure 14 (d represents the output terminal of the shutdown circuit).

[0152] It should be noted that when the drive circuit 301 is set at the input terminal of the electrical equipment, the drive circuit 301 draws power from the input terminal of the electrical equipment. When the reverse voltage passes through the body diode of the transverse MOS in the circuit topology of the equipment to the input terminal, the drive circuit 301 is energized, and the drive switch circuit 302 is turned on to achieve the protection effect. This is equivalent to adding hysteresis, which can reduce the frequency of hiccups.

[0153] It should be noted that, in the embodiments of this application, the energy is bidirectionally conducted at both the voltage input and voltage output terminals of the electrical equipment, so as to... Figure 14Taking 'a' as an example, the electrical equipment is a step-down circuit. The voltage at the input terminal of the step-down circuit can be output to the output terminal of the step-down circuit through the second switching device S2 and the inductor L1. If the input terminal of the step-down circuit is open at this time, the voltage at the output terminal of the step-down circuit can be output to the input terminal of the step-down circuit through the second switching device S2 and the inductor L1. That is, the voltage can go from the input terminal to the output terminal, and the voltage can go from the output terminal to the input terminal. This characteristic is called bidirectional energy conduction.

[0154] As an example, with Figure 14 Taking the driving circuit 301 shown in b as an example, when the input of the buck circuit is open, the voltage at the output of the buck circuit may be reverse-fed to the input through the inductor L and the body diode of the second switching device S2. When the output voltage exceeds the maximum voltage allowed by the driving circuit 301, the driving circuit 301 will drive the first switching device S1 to conduct. The first switching device S1 can short-circuit the input of the buck circuit, thereby forming a temporary current loop to avoid continuous voltage accumulation and thus protect the equipment.

[0155] In one possible implementation, to save on hardware costs, the electrical device may include a third switching device and a fourth switching device, wherein the first end of the third switching device is connected to the positive terminal of the output terminal of the electrical device, the second end of the third switching device is connected to the negative terminal of the output terminal of the electrical device, the first end of the fourth switching device is connected to the positive terminal of the output terminal of the electrical device, and the second end of the fourth switching device is connected to the first end of the third switching device.

[0156] Combination Figure 15 As shown, when the electrical equipment is a boost-buck circuit, the switching devices in the switching circuit 302 can be the third switching device S3 and the fourth switching device S4 in the boost-buck circuit, and the drive circuit 301 can be set at the output terminal of the boost-buck circuit.

[0157] It should be understood that when the input of the boost-buck circuit is open, the output of the boost-buck circuit may experience rapid voltage accumulation. When the output voltage exceeds the maximum voltage allowed by the drive circuit 301, the drive circuit 301 will drive the third switch S3 and the fourth switch S4 to conduct. The third switch S3 and the fourth switch S4 can short-circuit the output of the boost-buck circuit, thereby forming a temporary current loop to prevent continuous voltage accumulation and thus protect the equipment.

[0158] It should be noted that in the embodiments of this application, the energy is unidirectionally conducted between the input and output terminals of the electrical equipment, so as to... Figure 15For example, consider an electrical device that 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 through inductor L1 and the body diode of the fourth switching device S4. If the input of the boost-buck circuit is open at this time, the voltage at the output of the boost-buck circuit cannot be output to the input of the boost-buck circuit through the fourth switching device S4 and inductor L1. That is, the characteristic that voltage can flow from the input to the output, but cannot flow from the output to the input, is called unidirectional energy conduction.

[0159] It should be understood that, in the embodiments of this application, by using the main power device of the DC-to-DC circuit as the switching device in the switching circuit of the protection circuit, the equipment is protected while saving hardware costs.

[0160] Based on the protection circuit provided in the above embodiments, this application also provides an optimizer, which includes the protection circuit as described in any of the above embodiments.

[0161] Based on the protection circuits provided in the above embodiments, this application also provides a shutdown device, which includes the protection circuits described in any of the above embodiments.

[0162] Based on the protection circuit provided in the above embodiments

[0163] Combination Figure 16 As shown, this application embodiment also provides a photovoltaic system 1600, including at least one optimizer 1601 and at least one inverter 1602;

[0164] The output terminal of each optimizer 1601 is connected to the input terminal of the corresponding inverter 1602; the input terminal of the optimizer 1601 is connected to the output terminal of the corresponding photovoltaic module; the optimizer 1601 is the optimizer described in any of the above embodiments.

[0165] Inverter 1602 is used to receive DC power output from the corresponding optimizer 1601 and to invert DC power into AC power to supply power to the load.

[0166] The inverter is the core equipment of a photovoltaic system. Its main function is to convert the direct current (DC) output from the optimizer into alternating current (AC) suitable for grid use. In some implementations, the inverter is also responsible for monitoring parameters such as current, voltage, and frequency in the solar photovoltaic system and adjusting them according to system requirements to ensure the normal operation of the system.

[0167] It should be noted that the output terminals of each optimizer are connected in series as the output terminal, and this output terminal is connected to the corresponding inverter. The number of optimizers is not limited, nor is the connection between optimizers and inverters one-to-one or many-to-one. All connection relationships between optimizers and inverters in photovoltaic systems within this field are within the scope of protection of this invention.

[0168] 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. Each embodiment focuses on describing the differences from other embodiments.

[0169] In the embodiments of this application, the terms "first" and "second" (if they exist) are used only as name identifiers and do not represent the order of first and second.

[0170] The above description is merely one specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A protection circuit, characterized in that, The protection circuit is installed inside the electrical equipment; the protection circuit is connected in parallel to the first terminal of the electrical equipment; the first terminal of the electrical equipment is the voltage input terminal and / or voltage output terminal of the electrical equipment. The protection circuit is activated when the voltage input terminal is open, or when the voltage at the first terminal of the electrical equipment is greater than a preset voltage.

2. The circuit according to claim 1, characterized in that, Also includes: Controller; The auxiliary power supply for the controller is provided by the voltage input terminal; The controller is used to disconnect the protection circuit when the voltage at the voltage input terminal is not zero. Alternatively, when the voltage at the voltage input terminal of the electrical equipment is not zero and the voltage at the voltage output terminal is greater than the preset voltage, the protection circuit is controlled to be turned on. Alternatively, when the voltage at the voltage input terminal of the electrical equipment is greater than the preset voltage, the protection circuit is controlled to turn on.

3. The circuit according to claim 1, characterized in that, The protection circuit includes a drive circuit and a switch circuit; the drive circuit is connected to a first terminal of the switch circuit; the drive circuit is configured to be connected in parallel to a first terminal of the electrical equipment to be protected; the second terminal of the switch circuit is connected to the positive terminal of the first terminal of the electrical equipment, and the third terminal of the switch circuit is connected to the negative terminal of the first terminal of the electrical equipment. The driving circuit is configured to drive the second and third terminals of the switching circuit to conduct in response to a voltage at the first terminal of the electrical device being greater than a preset voltage threshold, wherein the preset voltage threshold is greater than the normal operating voltage at the first terminal of the electrical device.

4. The circuit according to claim 3, characterized in that, 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 terminal of the first terminal of the electrical device, 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 terminal of the first terminal of the electrical device.

5. The circuit according to claim 4, characterized in that, The driving circuit also includes a first resistor, a second resistor, a third resistor, a fourth resistor, a second Zener diode, a first switching device, and a second switching device; Wherein, 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 terminal of the first terminal of the electrical equipment; 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 Zener diode; 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 Zener diode and the positive terminal of the first terminal of the electrical equipment; 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 Zener diode and the negative terminal of the first terminal of the electrical equipment; and the first end of the Zener diode is connected to the second end of the second Zener diode and the first terminal of the switching circuit.

6. The circuit according to claim 4, characterized in that, The driving circuit further includes: a fifth resistor; The first end of the Zener diode is connected to the first end of the fifth resistor, the second end of the Zener diode is connected to the positive terminal of the first terminal of the electrical device, the second end of the fifth resistor is connected to the first end of the capacitor and the first terminal of the switching circuit, and the second end of the capacitor is connected to the negative terminal of the first terminal of the electrical device.

7. The circuit according to claim 4, characterized in that, The driving circuit also includes: a sixth resistor and a diode; The first end of the Zener diode is connected to the first end of the sixth resistor and the first end of the diode. The second end of the Zener diode is connected to the positive terminal of the first terminal of the electrical device. The second end of the diode is connected to the first terminal of the switching circuit. The first end of the capacitor is connected to the first end of the diode. The second end of the capacitor is connected to the second end of the sixth resistor and the negative terminal of the first terminal of the electrical device.

8. The circuit according to claim 1, characterized in that, Also includes: Controller; The protection circuit includes a drive circuit and a switch circuit; the controller is connected to a first terminal of the drive circuit; a second terminal of the drive circuit is connected to a first terminal of the switch circuit; a second terminal of the switch circuit is connected to the positive terminal of the first terminal of the electrical equipment, and a third terminal of the switch circuit is connected to the negative terminal of the first terminal. When the voltage at the first terminal of the electrical device is greater than a preset voltage threshold, the controller controls the drive circuit to turn on the second and third terminals of the switching circuit, wherein the preset voltage threshold is greater than the normal operating voltage at the first terminal of the electrical device.

9. The circuit according to claim 8, characterized in that, The driving circuit includes a seventh resistor, an eighth resistor, a ninth resistor, a third switching device, a fourth switching device, a fifth switching device, a Zener diode, a diode, and a second capacitor; Wherein, the first end of the seventh resistor is connected to the positive terminal of the first terminal of the electrical device; the second end of the seventh resistor is connected to the third terminal of the fifth switching device and the second terminal of the diode; the first and second ends of the eighth resistor are respectively connected to the third terminal of the third switching device and the first end of the ninth resistor; the common terminal of the eighth and ninth resistors is connected to the second terminal of the diode; the second end of the ninth resistor is connected to the first terminal of the fourth switching device and the first terminal of the second capacitor; the first end of the third switching device is connected to the positive terminal of the first terminal of the electrical device; the first end of the third switching device is also connected to the third terminal of the fourth switching device; the second end of the third switching device is connected to the positive terminal of the first terminal of the electrical device; the second end of the fourth switching device is connected to the second terminal of the second capacitor; the second end of the fifth switching device is connected to the negative terminal of the first terminal of the electrical device; the first end of the fifth switching device is connected to the output terminal of the controller; the first end of the Zener diode is connected to the first terminal of the switching circuit; the second end of the Zener diode is connected to the positive terminal of the first terminal of the electrical device; the first end of the diode is connected to the first end of the Zener diode; and the second capacitor is connected to the negative terminal of the first terminal of the electrical device.

10. The circuit according to claim 9, characterized in that, The driving circuit further includes: a tenth resistor, an eleventh resistor, a twelfth resistor, and a thirteenth resistor; Wherein, the first end of the tenth resistor is connected to the positive terminal of the first terminal of the electrical device, the second end of the tenth resistor is connected to the first terminal of the third switching device, the first end and the second end of the eleventh resistor are respectively connected to the first terminal of the third switching device and the third terminal of the fourth switching device, the first end and the second end of the twelfth resistor are respectively connected to the first terminal of the fifth switching device and the output terminal of the controller, the first end of the thirteenth resistor is connected to the first terminal of the fifth switching device, and the second end of the thirteenth resistor is connected to the negative terminal of the first terminal of the electrical device.

11. The circuit according to any one of claims 1-10, characterized in that, When the protection circuit includes a switching circuit, the switching circuit is any one of the following: depletion-mode metal-oxide-semiconductor field-effect transistor (MOSFET), junction field-effect transistor (JFET), or gallium nitride high electron mobility transistor (GaN HEMT).

12. The circuit according to any one of claims 1-10, characterized in that, The electrical equipment is a DC-to-DC circuit, and the switching device in the switching circuit is the main power device in the DC-to-DC circuit. The DC-to-DC circuit includes any one of the following: a buck circuit, a boost-buck circuit, or a shutdown device.

13. The circuit according to any one of claims 1-10, characterized in that, The electrical equipment includes a voltage input terminal and a voltage output terminal; The voltage input terminal and the voltage output terminal are bidirectionally connected, and the first terminal of the electrical equipment includes either the voltage input terminal or the voltage output terminal; or, Energy is unidirectionally conducted from the voltage output terminal to the voltage input terminal, and the first terminal of the electrical equipment includes the voltage output terminal.

14. The circuit according to any one of claims 1-10, characterized in that, The switching circuit is a MOSFET or a thyristor.

15. An optimizer, characterized in that, The optimizer includes the protection circuitry as described in any one of claims 1-14.

16. A switch, characterized in that, The shutdown device includes the protection circuit as described in any one of claims 1-14.

17. A photovoltaic system, characterized in that, The system includes at least one optimizer and at least one inverter; The optimizer's output is connected to the corresponding inverter's input; the optimizer's input is connected to the corresponding photovoltaic module's output; the optimizer includes a protection circuit as described in any one of claims 1-14; the inverter receives the DC power output from the optimizer and converts the DC power into AC power to supply power to the load.

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