Overvoltage protection circuit and energy storage power supply

Abstract

The invention discloses an overvoltage protection circuit and an energy storage power supply, and the overvoltage protection circuit comprises a power supply circuit which is connected between a first line and a second line, and is used for converting a first voltage of a photovoltaic input interface into a second voltage, and outputting a reference voltage according to the second voltage; the sampling circuit is connected between the first line and the second line; the first input end of the comparison circuit is connected with the power supply circuit, and the second input end of the comparison circuit is connected with the sampling circuit to receive sampling voltage; the main switch circuit is arranged on the second line, the output end of the comparison circuit is connected with the main switch circuit, and the delay circuit is used for controlling the comparison circuit to control the main switch circuit to be connected or disconnected according to the sampling voltage and the reference voltage when the second voltage is larger than or equal to the first preset voltage. Overvoltage protection can be realized, and overvoltage of the photovoltaic input interface is avoided; and the main switch circuit is prevented from being damaged due to serious heating in the amplification area for a long time after the second voltage is smaller than the first preset voltage.

Description

Technical Field

[0001] The present application relates to the technical field of power supplies, and particularly to an overvoltage protection circuit and an energy storage power supply. Background Art

[0002] The energy storage power supply includes a plurality of photovoltaic input interfaces, and each photovoltaic input interface is independently arranged. In order to ensure the power generation of the energy storage power supply under low light conditions, usually at least two photovoltaic modules are connected in parallel to the photovoltaic input interface, and the photovoltaic input interface is usually designed according to the voltage of a single photovoltaic module.

[0003] In the case where at least two photovoltaic modules are misconnected in series to the photovoltaic input interface, the voltage of the at least two photovoltaic modules connected in series is much greater than the voltage of a single photovoltaic module, resulting in an overvoltage problem at the photovoltaic input interface. Summary of the Invention

[0004] The main technical problem to be solved by the present application is to provide an overvoltage protection circuit and an energy storage power supply, which can solve the overvoltage problem at the photovoltaic input interface.

[0005] The present application provides an overvoltage protection circuit, which is applied to an energy storage power supply. The energy storage power supply includes at least one photovoltaic input interface. The photovoltaic input interface is used to connect to the MPPT circuit in the energy storage power supply. The photovoltaic input interface includes a high voltage terminal and a low voltage terminal. The high voltage terminal is connected to the MPPT circuit through a first line, and the low voltage terminal is connected to the MPPT circuit through a second line. The overvoltage protection circuit includes:

[0006] A power supply circuit, connected between the first line and the second line, for converting the first voltage of the photovoltaic input interface into a second voltage and outputting a reference voltage according to the second voltage;

[0007] A sampling circuit, connected between the first line and the second line;

[0008] A comparison circuit, the first input terminal of the comparison circuit is connected to the power supply circuit to receive the second voltage and the reference voltage from the power supply circuit, the second input terminal of the comparison circuit is connected to the sampling circuit to receive the sampled voltage;

[0009] A main switch circuit, arranged on the second line, and the output terminal of the comparison circuit is connected to the main switch circuit;

[0010] A delay circuit, respectively connected to the power supply circuit and the comparison circuit. The delay circuit is used to control the comparison circuit to control the main switch circuit to conduct or disconnect according to the sampled voltage and the reference voltage when the second voltage is greater than or equal to a first preset voltage.

[0011] Among them, the delay circuit is used to output a first level to the comparison circuit when the second voltage is less than the first preset voltage, and the comparison circuit is used to control the main switch circuit to remain off when receiving the first level;

[0012] The delay circuit is used to output a second level to the comparison circuit when the second voltage is greater than or equal to the first preset voltage; the comparison circuit is used to control the main switch circuit to conduct when receiving the second level and the sampling voltage is less than or equal to the reference voltage, or, the comparison circuit controls the main switch circuit to remain off when receiving the second level and the sampling voltage is greater than the reference voltage.

[0013] Among them, the delay circuit includes a current limiting unit, a first voltage stabilizing unit, a first switching unit, and a voltage dividing unit. The first end of the first voltage stabilizing unit and the first end of the first switching unit are connected to the power supply circuit through the current limiting unit, the first end of the first voltage stabilizing unit and the first end of the first switching unit are connected to the enabling end of the comparison circuit, the control end of the first switching unit is connected to the voltage dividing unit, the first end of the voltage dividing unit is connected to the power supply circuit, and the second ends of the first voltage stabilizing unit, the first switching unit, and the voltage dividing unit are all connected to the second line.

[0014] Among them, the delay circuit further includes a second voltage stabilizing unit and a filtering unit. The voltage dividing unit is connected to the power supply circuit through the second voltage stabilizing unit, and the control end of the first switching unit is connected to the voltage dividing unit through the filtering unit.

[0015] Among them, when the second voltage is less than the first preset voltage, the first switching unit is off, the power supply circuit supplies power to the first voltage stabilizing unit through the current limiting unit, and the enabling end of the comparison circuit receives the first level; or, when the second voltage is greater than or equal to the first preset voltage, the first switching unit is on, and the enabling end of the comparison circuit receives the second level.

[0016] Among them, the first switching unit includes a first switch, the current limiting unit includes a first resistor, the first voltage stabilizing unit includes a first voltage stabilizing diode, the voltage dividing unit includes a third resistor and a fourth resistor, the second voltage stabilizing unit includes a second voltage stabilizing diode, the filtering unit includes a first capacitor and a second resistor. The first end of the first switching tube is connected to the power supply circuit through the first resistor, the negative electrode of the first voltage stabilizing diode and the enabling end of the comparison circuit are connected to the first end of the first switching tube, and the control end of the first switching tube is connected to the power supply circuit through the second resistor, the third resistor, and the second voltage stabilizing diode; one end of the first capacitor and one end of the fourth resistor are connected between the second resistor and the third resistor, and the positive electrode of the first voltage stabilizing diode, the other end of the first capacitor, the other end of the fourth resistor, and the second end of the first switching tube are grounded.

[0017] Among them, the main switch circuit includes a driving circuit and a second switching tube. The second switching tube is arranged on the second line. The output end of the comparison circuit is connected to the control end of the second switching tube through the driving circuit. The comparison circuit is used to output a second level to the driving circuit when the sampled voltage is greater than the reference voltage, and the driving circuit is used to control the second switching tube to turn off when receiving the second level.

[0018] Among them, the comparison circuit is used to output a first level to the driving circuit when the sampled voltage is less than or equal to the reference voltage, and the driving circuit is used to control the second switching tube to turn on when receiving the first level; among them, the conduction speed at which the driving circuit controls the second switching tube to turn on is greater than the turn-off speed at which the driving circuit controls the second switching tube to turn off.

[0019] Among them, the power supply circuit includes a voltage stabilizing circuit and a reference voltage circuit. The voltage stabilizing circuit is connected between the first line and the second line and is used to convert the first voltage into a second voltage. The reference voltage circuit is respectively connected to the voltage stabilizing circuit and the comparison circuit and is used to output a reference voltage according to the second voltage.

[0020] Among them, the comparison circuit includes a comparator and a voltage stabilizing unit. The first input end of the comparator is connected to the reference voltage circuit. The first power supply end of the comparator is connected to the voltage stabilizing circuit. The enable end of the comparator is connected to the delay circuit. The second input end of the comparator is connected to the sampling circuit. The output end of the comparator is connected to the first input end of the comparator through the voltage stabilizing unit and is also connected to the main switch circuit.

[0021] Among them, the driving circuit includes a fifth resistor, a sixth resistor, a seventh resistor and a first diode. The positive electrode of the first diode and one end of the sixth resistor are connected to the output end of the comparator through the fifth resistor. The negative electrode of the first diode and the other end of the sixth resistor are connected to the control end of the second switching tube. One end of the seventh resistor is connected to the second line, and the other end of the seventh resistor is connected to the control end of the second switching tube.

[0022] Among them, the voltage stabilizing unit includes a second capacitor, an eighth resistor and a ninth resistor. The output end of the comparator is connected to the first input end of the comparator through the eighth resistor. One end of the ninth resistor and one end of the second capacitor are connected to the first input end of the comparator. The other end of the ninth resistor and the other end of the second capacitor are connected to the second line;

[0023] The sampling circuit includes a tenth resistor and an eleventh resistor. The tenth resistor and the eleventh resistor are connected between the first line and the second line. The second input end of the comparator is connected between the tenth resistor and the eleventh resistor.

[0024] Among them, the reference voltage circuit includes a third zener diode and a twelfth resistor, and the comparison circuit further includes a thirteenth resistor. The first end of the third zener diode is connected to the voltage regulation circuit through the twelfth resistor. The second end of the third zener diode is connected to the second line. The third end of the third zener diode is connected to the first end. The first end of the third zener diode is connected to the second input terminal of the comparator through the thirteenth resistor.

[0025] Among them, the voltage regulation circuit includes a third switching transistor, a fourth switching transistor, a fourteenth resistor, a fifteenth resistor, a third capacitor, a fourth zener diode, a fourth capacitor and a fifth capacitor. The first ends of the third switching transistor and the fourth switching transistor are connected to the first line through the fourteenth resistor. The second end of the third switching transistor is connected to the twelfth resistor and the first power supply terminal of the comparator. The third end of the third switching transistor is connected to the second end of the fourth switching transistor. The third end of the fourth switching transistor is connected to the second line through the fourth zener diode. One end of the fifteenth resistor is connected to the first end of the third switching transistor. The other end of the fifteenth resistor and one end of the third capacitor are connected to the second end of the third switching transistor. The other end of the third capacitor is connected to the second line. One end of the fourth capacitor and one end of the fifth capacitor are connected to the second end of the third switching transistor. The other end of the fourth capacitor and the other end of the fifth capacitor are connected to the second line.

[0026] This application further provides an energy storage power supply, including at least one photovoltaic input interface, an MPPT circuit, and the above overvoltage protection circuit. The photovoltaic input interface is used to connect to the MPPT circuit. The photovoltaic input interface includes a high voltage terminal and a low voltage terminal. The high voltage terminal is connected to the MPPT circuit through the first line. The low voltage terminal is connected to the MPPT circuit through the second line. The overvoltage protection circuit is connected between the first line and the second line.

[0027] The beneficial effects of the present application are as follows: The overvoltage protection circuit of the present application is applied to an energy storage power supply. The energy storage power supply has at least one photovoltaic input interface, and the photovoltaic input interface is used to connect to the MPPT circuit in the energy storage power supply. The overvoltage protection circuit includes a power supply circuit, a sampling circuit, a comparison circuit, a delay circuit, and a main switch circuit. The first input terminal of the comparison circuit is connected to the power supply circuit to receive a second voltage and a reference voltage from the power supply circuit. The second input terminal of the comparison circuit is connected to the sampling circuit to receive a sampling voltage. The main switch circuit is disposed on the second line, and the output terminal of the comparison circuit is connected to the main switch circuit. The delay circuit is respectively connected to the power supply circuit and the comparison circuit. The delay circuit is configured to control the comparison circuit to control the conduction or disconnection of the main switch circuit according to the sampling voltage and the reference voltage when the second voltage is greater than or equal to a first preset voltage. By comparing the sampling voltage and the reference voltage through the comparison circuit to control the conduction or disconnection of the main switch circuit according to the comparison result, the main switch circuit is controlled to disconnect in the case of overvoltage at the photovoltaic input interface, which can achieve overvoltage protection, avoid overvoltage at the photovoltaic input interface, has a simple circuit, and reduces costs. In addition, the delay circuit is configured to control the comparison circuit to control the conduction or disconnection of the main switch circuit according to the sampling voltage and the reference voltage when the second voltage is greater than or equal to the first preset voltage, that is, the delay circuit controls the main switch circuit to remain disconnected through the comparison circuit when the second voltage is less than the first preset voltage, avoiding the main switch circuit from being damaged due to serious heating in the amplification region after being conducted when the second voltage is less than the first preset voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings. Among them:

[0029] Figure 1 is a schematic framework diagram of an embodiment of the overvoltage protection circuit provided by the present application;

[0030] Figure 2 is Figure 1 a schematic circuit diagram of an embodiment of the delay circuit in

[0031] Figure 3 is Figure 1 a schematic circuit diagram of another embodiment of the delay circuit in

[0032] Figure 4 is Figure 1 a schematic circuit diagram of an embodiment of the overvoltage protection circuit in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The embodiments of the technical solution of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solution of the present application more clearly, so they are only examples and cannot be used to limit the protection scope of the present application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0035] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features.

[0036] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0037] In the description of the embodiments of this application, the term "plurality" means two or more (including two). Similarly, "multiple groups" means two or more groups (including two groups), and "multiple pieces" means two or more pieces (including two pieces).

[0038] In the description of the embodiments of this application, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the embodiments of this application.

[0039] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0040] The energy storage power supply is applied to balcony photovoltaics. To improve efficiency, the energy storage power supply includes multiple photovoltaic input interfaces, and each photovoltaic input interface is independently set. To ensure the power generation of the energy storage power supply under low-light conditions, usually at least two photovoltaic modules are connected in parallel to the photovoltaic input interface, and the photovoltaic input interface is usually designed according to the voltage of a single photovoltaic module. In the case where at least two photovoltaic modules are misconnected in series to the photovoltaic input interface, the voltage of at least two photovoltaic modules connected in series is much greater than the voltage of a single photovoltaic module, resulting in an overvoltage problem at the photovoltaic input interface. For example, the photovoltaic input interface is designed according to a voltage of 60V, the maximum voltage of a single photovoltaic module is 60V, and the voltage of two photovoltaic modules connected in series is 120V. When two photovoltaic modules connected in series are connected to the photovoltaic input interface, an overvoltage problem occurs at the photovoltaic input interface.

[0041] In the prior art, a differential signal can be sampled and given to a DSP (Digital Signal Processing), but since the ground of the gate of the switching tube and the subsequent DSP is not common, an isolation drive circuit is required to drive the switching tube, that is, an isolated power supply needs to be established for the drive circuit. Assuming there are 4 photovoltaic input interfaces, at this time, 4 isolated power supplies need to be established, the circuit is complex and the cost is high. In addition, the photovoltaic module powers the DSP. When two photovoltaic modules connected in series power the DSP, the isolated power supply needs to be designed according to 120V, increasing the cost.

[0042] The energy storage power supply in the prior art is a small-power power supply. The switching tube of the overvoltage protection circuit is arranged at the positive pole of the energy storage power supply, and a PMOS is selected for the switching tube. For a high-power energy storage power supply, the current is large, and a PMOS with a smaller internal resistance needs to be selected. It is difficult to find a PMOS with a smaller internal resistance, and the cost is high.

[0043] Please refer to Figure 1 as shown in Figure 1It is a schematic framework diagram of an embodiment of the overvoltage protection circuit provided by this application. The overvoltage protection circuit 10 of this embodiment is applied to the energy storage power supply 1. The energy storage power supply 1 has at least one photovoltaic input interface 20, and the photovoltaic input interface 20 is used to connect to the MPPT (Maximum Power Point Tracking) circuit 30 in the energy storage power supply 1. For example, the energy storage power supply 1 is applied to balcony photovoltaics.

[0044] The photovoltaic input interface 20 includes a high voltage terminal PV+ and a low voltage terminal PV-. The high voltage terminal PV+ is connected to the MPPT circuit 30 through the first line 21, and the low voltage terminal PV- is connected to the MPPT circuit 30 through the second line 22. Among them, the MPPT circuit 30 is an MPPT circuit of the prior art and will not be elaborated here.

[0045] In some embodiments, the photovoltaic input interface 20 can be connected to at least two photovoltaic modules, and the at least two photovoltaic modules are connected in parallel to ensure the power generation of the energy storage power supply 1 under low light conditions; for example, the photovoltaic input interface 20 is connected to two photovoltaic modules connected in parallel.

[0046] The overvoltage protection circuit 10 of this embodiment includes a power supply circuit 11, a sampling circuit 12, a comparison circuit 13, a delay circuit 14, and a main switch circuit 15.

[0047] The power supply circuit 11 is connected between the first line 21 and the second line 22. The power supply circuit 11 receives the first voltage from the photovoltaic input interface 20 through the first line 21 and the second line 22. The first voltage can be the power supply voltage of the energy storage power supply 1. The power supply circuit 11 is used to convert the first voltage into a second voltage and output a reference voltage according to the second voltage; the power supply circuit 11 can provide the second voltage and the reference voltage for the comparison circuit 13.

[0048] The sampling circuit 12 is connected between the first line 21 and the second line 22. The sampling circuit 12 receives the first voltage from the photovoltaic input interface 20 through the first line 21 and the second line 22. The sampling circuit 12 can be used to sample the first voltage to obtain a sampling voltage.

[0049] The first input terminal of the comparison circuit 13 is connected to the power supply circuit 11, and receives the second voltage and the reference voltage from the power supply circuit 11; the second input terminal of the comparison circuit 13 is connected to the sampling circuit 12, and receives the sampling voltage from the sampling circuit 12.

[0050] The main switch circuit 15 is arranged on the second line 22. The output terminal of the comparison circuit 13 is connected to the main switch circuit 15. The comparison circuit 13 is used to control the main switch circuit 15 to conduct or disconnect.

[0051] The delay circuit 14 is respectively connected to the power supply circuit 11 and the comparison circuit 13. The delay circuit 14 is configured to control the comparison circuit 13 to control the conduction or disconnection of the main switch circuit 15 according to the sampled voltage and the reference voltage when the second voltage is greater than or equal to the first preset voltage.

[0052] Wherein, the main switch circuit 15 is disposed on the second line 22 means that one end of the main switch circuit 15 is connected to the low voltage terminal PV- through the second line 22, and the other end of the main switch circuit 15 is connected to the MPPT circuit 30 through the second line 22. When the second voltage is greater than or equal to the first preset voltage, the delay circuit 14 controls the comparison circuit 13 to control the conduction or disconnection of the main switch circuit 15 according to the sampled voltage and the reference voltage.

[0053] Since the comparison circuit 13 is configured to turn on the switching tube of the main switch circuit 15 when the second voltage is greater than or equal to the first preset voltage, the switching tube of the main switch circuit 15 is in the amplification region when the second voltage is less than the first preset voltage. At this time, the switching tube of the main switch circuit 15 is prone to overheating and damage. In this embodiment, when the second voltage is greater than or equal to the first preset voltage, the delay circuit 14 controls the comparison circuit 13 to control the conduction or disconnection of the main switch circuit 15 according to the sampled voltage and the reference voltage; when the second voltage is less than the first preset voltage, the delay circuit 14 controls the main switch circuit 15 to remain disconnected, avoiding the main switch circuit 15 from being damaged due to serious heating in the amplification region for a long time after being turned on when the second voltage is less than the first preset voltage.

[0054] The overvoltage protection circuit 10 of this embodiment includes a power supply circuit 11, a sampling circuit 12, a comparison circuit 13, a delay circuit 14, and a main switch circuit 15. The first input terminal of the comparison circuit 13 is connected to the power supply circuit 11 to receive a second voltage and a reference voltage from the power supply circuit 11. The second input terminal of the comparison circuit 13 is connected to the sampling circuit 12 to receive a sampling voltage. The main switch circuit 15 is disposed on the second line 22, and the output terminal of the comparison circuit 13 is connected to the main switch circuit 15. By comparing the sampling voltage and the reference voltage through the comparison circuit 13, the conduction or disconnection of the main switch circuit 15 is controlled according to the comparison result. When the photovoltaic input interface 20 is overvoltage, the main switch circuit 15 is controlled to disconnect, which can achieve overvoltage protection, avoid overvoltage of the photovoltaic input interface 20, the circuit is simple, and the cost is reduced. In addition, the delay circuit 14 is respectively connected to the power supply circuit 11 and the comparison circuit 13. The delay circuit 14 is used to control the comparison circuit 13 to control the conduction or disconnection of the main switch circuit 15 according to the sampling voltage and the reference voltage when the second voltage is greater than or equal to a first preset voltage. That is, when the second voltage is less than the first preset voltage, the delay circuit 14 controls the main switch circuit 15 to remain disconnected through the comparison circuit 13, realizing delayed startup, and avoiding serious heating and damage of the main switch circuit 15 in the amplification region after being conducted when the second voltage is less than the first preset voltage. In addition, by disposing the main switch circuit 15 on the second line 22, it is applicable to the high-power energy storage power supply 1, without the need to find a switching tube with a smaller internal resistance, reducing the cost.

[0055] According to some embodiments of the present application, the delay circuit 14 of this embodiment is used to output a first level to the comparison circuit 13 when the second voltage is less than the first preset voltage, and the comparison circuit 13 is used to control the main switch circuit 15 to disconnect when receiving the first level. For example, the first preset voltage is 10.5V. The delay circuit 14 is used to output a first level to the comparison circuit 13 when the second voltage is less than 10.5V. The comparison circuit 13 outputs a second level when receiving the first level, and controls the main switch circuit 15 to disconnect through the second level, that is, the switching tube of the main switch circuit 15 disconnects. The first level is a high level, and the second level is a low level.

[0056] The delay circuit 14 is used to output a second level to the comparison circuit 13 when the second voltage is greater than or equal to the first preset voltage. The comparison circuit 13 is used to control the main switch circuit 15 to conduct when receiving the second level and the sampling voltage is less than or equal to the reference voltage; or, the comparison circuit 13 is used to control the main switch circuit 15 to disconnect when receiving the second level and the sampling voltage is greater than the reference voltage.

[0057] For example, the delay circuit 14 is used to output a low level to the comparison circuit 13 when the second voltage is greater than or equal to 10.5V. The comparison circuit 13 controls the conduction or disconnection of the main switch circuit 15 according to the sampled voltage and the reference voltage. Among them, the comparison circuit 13 is used to output a high level when the sampled voltage is less than or equal to the reference voltage to control the conduction of the main switch circuit 15; or, the comparison circuit 13 is used to output a low level when the sampled voltage is greater than the reference voltage to control the disconnection of the main switch circuit 15.

[0058] The delay circuit 14 in this embodiment is used to output a first level to the comparison circuit 13 when the second voltage is less than the first preset voltage. The comparison circuit 13 is used to control the disconnection of the main switch circuit 15 when receiving the first level; to achieve delayed startup and avoid serious heat generation and damage of the main switch circuit 15 in the amplification region for a long time after being conducted when the second voltage is less than the first preset voltage. The comparison circuit 13 is used to output a high level when the sampled voltage is less than or equal to the reference voltage to control the conduction of the main switch circuit 15; or, the comparison circuit 13 is used to output a low level when the sampled voltage is greater than the reference voltage to control the disconnection of the main switch circuit 15, realizing level inversion; by controlling the disconnection of the main switch circuit 15, overvoltage protection is achieved to avoid overvoltage of the photovoltaic input interface 20.

[0059] According to some embodiments of the present application, please refer to Figure 1 and Figure 2 as shown in Figure 2 is Figure 1 a schematic circuit diagram of an embodiment of the delay circuit in

[0060] The first end of the first voltage stabilizing unit 142 and the first end of the first switch unit 143 are connected to the power supply circuit 11 through the current limiting unit 141. The first end of the first voltage stabilizing unit 142 and the first end of the first switch unit 143 are connected to the enable terminal SHDN of the comparison circuit 13. The control end of the first switch unit 143 is connected to the voltage dividing unit 144. The first end of the voltage dividing unit 144 is connected to the power supply circuit 11. The second end of the first voltage stabilizing unit 142, the second end of the first switch unit 143, and the second end of the voltage dividing unit 144 are all connected to the second line 22, that is, the second end of the first voltage stabilizing unit 142, the second end of the first switch unit 143, and the second end of the voltage dividing unit 144 are grounded.

[0061] When the second voltage is less than the first preset voltage, the voltage dividing unit 144 is used to divide the second voltage, and the voltage after division is lower than the conduction voltage of the first switching unit 143; the first switching unit 143 is turned off, and the power supply circuit 11 supplies power to the first voltage stabilizing unit 142 through the current limiting unit 141. The voltage received by the enable terminal SHDN of the comparison circuit 13 is the voltage of the first voltage stabilizing unit 142, that is, the enable terminal SHDN of the comparison circuit 13 receives the first level.

[0062] When the second voltage is greater than or equal to the first preset voltage, the voltage dividing unit 144 is used to divide the second voltage, and the voltage after division is equal to or greater than the conduction voltage of the first switching unit 143; the first switching unit 143 is turned on, and the power supply circuit 11 is connected to the second line 22 through the current limiting unit 141 and the first switching unit 143. The voltage received by the enable terminal SHDN of the comparison circuit 13 is the voltage of the second line 22, that is, the enable terminal SHDN of the comparison circuit 13 receives the second level.

[0063] The delay circuit 14 of this embodiment includes a current limiting unit 141, a first voltage stabilizing unit 142, a first switching unit 143, and a voltage dividing unit 144; when the second voltage is less than the first preset voltage, the first switching unit 143 is turned off, and the power supply circuit 11 supplies power to the first voltage stabilizing unit 142 through the current limiting unit 141. The enable terminal SHDN of the comparison circuit 13 receives the first level, and the comparison circuit 13 is used to control the main switching circuit 15 to turn off when receiving the first level; realizing delayed startup and avoiding damage to the main switching circuit 15 due to overheating in the amplification region for a long time after being turned on when the second voltage is less than the first preset voltage.

[0064] According to some embodiments of the present application, please refer to Figure 1 and Figure 3 as shown in Figure 3 is Figure 1 a schematic circuit diagram of another embodiment of the delay circuit in

[0065] In some embodiments, the first switching unit 143 includes a first switch Q1, the current limiting unit 141 includes a first resistor R1, the first voltage stabilizing unit 142 includes a first voltage stabilizing diode D1, the voltage dividing unit 144 includes a third resistor R3 and a fourth resistor R4, the second voltage stabilizing unit 145 includes a second voltage stabilizing diode D2, and the filtering unit 146 includes a first capacitor C1 and a second resistor R2.

[0066] Among them, the first end of the first switching transistor Q1 is connected to the power supply circuit 11 through the first resistor R1. The negative electrode of the first voltage stabilizing diode D1 and the enable terminal SHDN of the comparison circuit 13 are connected to the first end of the first switching transistor Q1. The control terminal of the first switching transistor Q1 is connected to the power supply circuit 11 through the second resistor R2, the third resistor R3, and the second voltage stabilizing diode D2. One end of the first capacitor C1 and one end of the fourth resistor R4 are connected between the second resistor R2 and the third resistor R3. The positive electrode of the first voltage stabilizing diode D1, the other end of the first capacitor C1, the other end of the fourth resistor R4, and the second end of the first switching transistor Q1 are grounded.

[0067] The first switching transistor Q1 is an N-type MOS transistor. The first end of the first switching transistor Q1 is the drain of the N-type MOS transistor. The second end of the first switching transistor Q1 is the source of the N-type MOS transistor. The control terminal of the first switching transistor Q1 is the gate of the N-type MOS transistor. In other embodiments, the first switching transistor Q1 can also be other types of switching transistors, such as P-type MOS transistors.

[0068] Among them, the power supply circuit 11 is used to provide a second voltage to the first resistor R1 and the second voltage stabilizing diode D2. When the second voltage is less than the first preset voltage, after the voltage drop of the second voltage stabilizing diode D2, the voltage division of the third resistor R3, and the fourth resistor R4, the voltage at the control terminal of the first switching transistor Q1 is lower than the conduction voltage of the first switching transistor Q1, and the first switching transistor Q1 is turned off. The power supply circuit 11 supplies power to the first voltage stabilizing diode D1 through the resistor R1, and the voltage received by the enable terminal SHDN of the comparison circuit 13 is the voltage of the first voltage stabilizing diode D1, that is, the enable terminal SHDN of the comparison circuit 13 receives a first level. For example, when the second voltage is less than 10.5V and the voltage of the first voltage stabilizing diode D1 is 3.3V, the voltage of the enable terminal SHDN of the comparison circuit 13 is 3.3V at this time, that is, it receives a high level.

[0069] When the second voltage is greater than or equal to the first preset voltage, after the voltage drop of the second voltage stabilizing diode D2, the voltage division of the third resistor R3, and the fourth resistor R4, the voltage at the control terminal of the first switching transistor Q1 is equal to the conduction voltage of the first switching transistor Q1, and the first switching transistor Q1 is turned on. The power supply circuit 11 is grounded through the resistor R1 and the first switching transistor Q1, and the enable terminal SHDN of the comparison circuit 13 receives a second level. For example, when the second voltage is greater than or equal to 10.5V, the voltage between the third resistor R3 and the fourth resistor R4 is 2.7V, the first switching transistor Q1 is turned on, and the power supply circuit 11 is grounded through the resistor R1 and the first switching transistor Q1. At this time, the voltage of the enable terminal SHDN of the comparison circuit 13 is 0V, that is, it receives a low level.

[0070] The delay circuit 14 of this embodiment includes a current limiting unit 141, a first voltage stabilizing unit 142, a first switching unit 143, a voltage dividing unit 144, a second voltage stabilizing unit 145, and a filtering unit 146. When the second voltage is less than the first preset voltage, the first switching unit 143 is turned off, and the power supply circuit 11 supplies power to the first voltage stabilizing unit 142 through the current limiting unit 141. The enable terminal SHDN of the comparison circuit 13 receives the first level, and the comparison circuit 13 is used to control the main switching circuit 15 to turn off when receiving the first level; realizing delayed startup to avoid the main switching circuit 15 being damaged due to overheating in the amplification region for a long time after being turned on when the second voltage is less than the first preset voltage.

[0071] According to some embodiments of the present application, please refer to Figure 1 and Figure 4 as shown in Figure 4 is Figure 1 a schematic circuit diagram of an embodiment of the overvoltage protection circuit in

[0072] The main switching circuit 15 of this embodiment includes a driving circuit 151 and a second switching transistor Q2.

[0073] The second switching transistor Q2 is disposed on the second line 22, and the output terminal of the comparison circuit 13 is connected to the control terminal of the second switching transistor Q2 through the driving circuit 151. Among them, the first end of the second switching transistor Q2 is connected to the low voltage terminal PV- through a part of the second line 22, and the second end of the second switching transistor Q2 is connected to the MPPT circuit 30 through a part of the second line 22.

[0074] The comparison circuit 13 is used to output a second level to the driving circuit 151 when the sampled voltage is greater than the reference voltage, and the driving circuit 151 controls the second switching transistor Q2 to turn off.

[0075] In some embodiments, when the first voltage is greater than the second preset voltage, the sampled voltage is greater than the reference voltage, and the comparison circuit 13 is used to output a second level to the driving circuit 151, so as to control the second switching transistor Q2 to turn off through the driving circuit 151 when receiving the second level. For example, the second preset voltage is 62V, and when two photovoltaic modules are connected in series, the first voltage is 120V, that is, the first voltage is greater than the second preset voltage, and at this time the sampled voltage is greater than the reference voltage.

[0076] The main switch circuit 15 of this embodiment includes a driving circuit 151 and a second switching transistor Q2. The comparison circuit 13 is configured to output a second level to the driving circuit 151 when the sampled voltage is greater than the reference voltage. The driving circuit 151 is configured to control the second switching transistor Q2 to turn off when receiving the second level. The comparison circuit 13 controls the second switching transistor Q2 to turn off through the driving circuit 151, achieving overvoltage protection and avoiding overvoltage at the photovoltaic input interface 20.

[0077] According to some embodiments of the present application, the comparison circuit 13 of this embodiment is configured to output a first level to the driving circuit 151 when the sampled voltage is less than or equal to the reference voltage. The driving circuit 151 is configured to control the second switching transistor Q2 to turn on when receiving the first level.

[0078] For example, when two photovoltaic modules are connected in parallel, the first voltage is 62V, that is, the first voltage is equal to the second preset voltage. At this time, the sampled voltage is equal to the reference voltage. The comparison circuit 13 outputs a high level to the driving circuit 151. The driving circuit 151 is configured to control the second switching transistor Q2 to turn on when receiving the first level. The low voltage terminal PV- is connected to the MPPT circuit 30 through the second line 22 and the second switching transistor Q2.

[0079] Among them, the conduction speed at which the driving circuit 151 controls the second switching transistor Q2 to turn on is greater than the turn-off speed at which the driving circuit 151 controls the second switching transistor Q2 to turn off.

[0080] In some embodiments, when the energy storage power supply 1 is just started, the MPPT circuit 30 has not yet worked. At this time, the currents in the first line 21 and the second line 22 are very small, that is, the current in the driving circuit 151 is very small. The comparison circuit 13 controls the second switching transistor Q2 to turn on through the driving circuit 151, achieving fast conduction. When the sampled voltage is greater than the reference voltage, that is, when the photovoltaic input interface 20 is overvoltage, the currents in the first line 21 and the second line 22 are very large, the current in the driving circuit 151 is large, the turn-off resistance of the second switching transistor Q2 is large, and the second switching transistor Q2 realizes slow turn-off. Therefore, the conduction speed at which the driving circuit 151 controls the second switching transistor Q2 to turn on is greater than the turn-off speed at which the driving circuit 151 controls the second switching transistor Q2 to turn off, reducing the interference generated due to current changes when the second switching transistor Q2 turns off.

[0081] According to some embodiments of the present application, please refer to Figure 1 and Figure 4 As shown, the power supply circuit 11 of this embodiment includes a voltage stabilizing circuit 111 and a reference voltage circuit 112. The voltage stabilizing circuit 111 is connected between the first line 21 and the second line 22 and is configured to convert the first voltage into a second voltage. The reference voltage circuit 112 is respectively connected to the voltage stabilizing circuit 111 and the comparison circuit 13 and is configured to output a reference voltage according to the second voltage.

[0082] The voltage stabilizing circuit 111 includes, but is not limited to, a low dropout regulator (LDO). The voltage stabilizing circuit 111 is used to supply power to the comparison circuit 13, providing a second voltage to achieve providing a stable voltage and improving the comparison accuracy of the comparison circuit 13. The reference voltage circuit 112 is used to output a reference voltage according to the second voltage to provide a reference voltage for the comparison circuit 13 and improve the accuracy of the reference voltage.

[0083] According to some embodiments of the present application, please refer to Figure 1 and Figure 4 As shown, the comparison circuit 13 of this embodiment includes a comparator 131 and a voltage stabilizing unit 132. The comparator 131 can be a comparator with a push-pull function, and the comparator 131 and the voltage stabilizing unit 132 can achieve the function of a hysteresis comparator.

[0084] The first input terminal of the comparator 131 is connected to the reference voltage circuit 112 to receive the reference voltage. The first power supply terminal of the comparator 131 is connected to the voltage stabilizing circuit 111 to receive the second voltage, realizing the power supply of the voltage stabilizing circuit 111 to the comparator 131. The enable terminal SHDN of the comparator 131 is connected to the delay circuit 14, the second input terminal of the comparator 131 is connected to the sampling circuit 12 to receive the sampling voltage; the output terminal of the comparator 131 is connected to the first input terminal of the comparator 131 through the voltage stabilizing unit 132 and is connected to the main switch circuit 15. Among them, the enable terminal SHDN of the comparator 131 is the enable terminal SHDN of the comparison circuit 13, the first input terminal of the comparator 131 is the first input terminal of the comparison circuit 13, the second input terminal of the comparator 131 is the second input terminal of the comparison circuit 13, and the output terminal of the comparator 131 is the output terminal of the comparison circuit 13.

[0085] Among them, the drive circuit 151 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and a diode D. The positive electrode of the diode D and one end of the sixth resistor R6 are connected to the output terminal of the comparator 131 through the fifth resistor R5. The negative electrode of the diode D and the other end of the sixth resistor R6 are connected to the control terminal of the second switching transistor Q2. One end of the seventh resistor R7 is connected to the second line 22, and the other end of the seventh resistor R7 is connected to the control terminal of the second switching transistor Q2.

[0086] Among them, the voltage stabilizing unit 132 includes a second capacitor C2, an eighth resistor R8, and a ninth resistor R9. The output terminal of the comparator 131 is connected to the first input terminal of the comparator 131 through the eighth resistor R8. One end of the ninth resistor R9 and one end of the second capacitor C2 are connected to the first input terminal of the comparator 131, and the other end of the ninth resistor R9 and the other end of the second capacitor C2 are connected to the second line 22.

[0087] The sampling circuit 12 includes a tenth resistor R10 and an eleventh resistor R11. The tenth resistor R10 and the eleventh resistor R11 are connected between the first line 21 and the second line 22. The second input terminal of the comparator 131 is connected between the tenth resistor R10 and the eleventh resistor R11 to receive the sampling voltage.

[0088] According to some embodiments of the present application, please refer to Figure 1 and Figure 4 As shown, the reference voltage circuit 112 of this embodiment includes a third voltage regulator diode D3 and a twelfth resistor R12. The comparison circuit 13 further includes a thirteenth resistor R13. The first end of the third voltage regulator diode D3 is connected to the voltage regulation circuit 111 through the twelfth resistor R12. The second end of the third voltage regulator diode D3 is connected to the second line 22. The third end of the third voltage regulator diode D3 is connected to the first end. The first end of the third voltage regulator diode D3 is connected to the second input terminal of the comparator 131 through the thirteenth resistor R13.

[0089] The third voltage regulator diode D3 can be used as a controllable precision voltage source. The output terminal of the voltage regulation circuit 111 supplies power to the third voltage regulator diode D3 and the twelfth resistor R12 to enable the reference voltage circuit 112 to output a stable reference voltage. For example, the reference voltage output by the reference voltage circuit 112 is 2.5V.

[0090] The reference voltage circuit 112 of this embodiment includes a third voltage regulator diode D3 and a twelfth resistor R12. The first end of the third voltage regulator diode D3 is connected to the voltage regulation circuit 111 through the twelfth resistor R12. The accurate reference voltage can be obtained through the third voltage regulator diode D3, improving the accuracy of the reference voltage.

[0091] According to some embodiments of the present application, please refer to Figure 1 and Figure 4 As shown, the voltage regulation circuit 111 of this embodiment includes a third switching transistor Q3, a fourth switching transistor Q4, a fourteenth resistor R14, a fifteenth resistor R15, a third capacitor C3, a fourth voltage regulator diode D4, a fourth capacitor C4, and a fifth capacitor C5.

[0092] The first terminal of the third switching transistor Q3 and the first terminal of the fourth switching transistor Q4 are connected to the first line 21 through the fourteenth resistor R14. The second terminal of the third switching transistor Q3 is connected to the twelfth resistor R12 and the first power supply terminal of the comparator 131. The third terminal of the third switching transistor Q3 is connected to the second terminal of the fourth switching transistor Q4. The third terminal of the fourth switching transistor Q4 is connected to the second line 22 through the fourth voltage regulator diode D4. One end of the fifteenth resistor R15 is connected to the first terminal of the third switching transistor Q3, and the other end of the fifteenth resistor R15 and one end of the third capacitor C3 are connected to the second terminal of the third switching transistor Q3. The other end of the third capacitor C3 is connected to the second line 22. One end of the fourth capacitor C4 and one end of the fifth capacitor C5 are connected to the second terminal of the third switching transistor Q3. The other end of the fourth capacitor C4 and the other end of the fifth capacitor C5 are connected to the second line 22. Among them, the fifteenth resistor R15 can be implemented by connecting multiple resistors in parallel; the fourth capacitor C4 and the fifth capacitor C5 are used to filter the second voltage output by the voltage regulator circuit 111.

[0093] In some embodiments, both the third switching transistor Q3 and the fourth switching transistor Q4 are NPN triodes. The first terminals of the third switching transistor Q3 and the fourth switching transistor Q4 are both the collectors of the NPN triodes. The second terminals of the third switching transistor Q3 and the fourth switching transistor Q4 are both the emitters of the NPN triodes. The third terminals of the third switching transistor Q3 and the fourth switching transistor Q4 are both the bases of the NPN triodes. In other embodiments, the third switching transistor Q3 and the fourth switching transistor Q4 can be other types of switching transistors, such as PNP triodes.

[0094] The voltage regulator circuit 111 of this embodiment can improve the input and output characteristics of the third switching transistor Q3 and the fourth switching transistor Q4 and increase the current amplification factor through the superposition of the third switching transistor Q3 and the fourth switching transistor Q4. When at least two photovoltaic modules are connected to the photovoltaic input interface 20, the third switching transistor Q3 and the fourth switching transistor Q4 can improve the output of the voltage regulator circuit 11 in low-light conditions.

[0095] This application also provides an energy storage power supply 1. Please refer to Figure 1 as shown. The energy storage power supply 1 includes at least one photovoltaic input interface 20, an MPPT circuit 30, and an overvoltage protection circuit 10. The overvoltage protection circuit 10 can be the overvoltage protection circuit 10 disclosed in the above embodiments, which will not be elaborated here.

[0096] The photovoltaic input interface 20 is used to connect to the MPPT circuit 30. For example, the energy storage power supply 1 is applied to balcony photovoltaics. The photovoltaic input interface 20 includes a high voltage terminal PV+ and a low voltage terminal PV-. The high voltage terminal PV+ is connected to the MPPT circuit 30 through the first line 21, and the low voltage terminal PV- is connected to the MPPT circuit 30 through the second line 22. The overvoltage protection circuit 10 is connected between the first line 21 and the second line 22 and can disconnect the photovoltaic input interface 20 in case of overvoltage.

[0097] In summary, the overvoltage protection circuit 10 of the present application includes a power supply circuit 11, a sampling circuit 12, a comparison circuit 13, a delay circuit 14, and a main switch circuit 15. The first input terminal of the comparison circuit 13 is connected to the power supply circuit 11 to receive the second voltage and the reference voltage from the power supply circuit 11. The second input terminal of the comparison circuit 13 is connected to the sampling circuit 12 to receive the sampling voltage. The main switch circuit 15 is arranged on the second line 22, and the output terminal of the comparison circuit 13 is connected to the main switch circuit 15. By comparing the sampling voltage and the reference voltage through the comparison circuit 13, the main switch circuit 15 is controlled to conduct or disconnect according to the comparison result. In the case of overvoltage of the photovoltaic input interface 20, the main switch circuit 15 is controlled to disconnect, which can achieve overvoltage protection, avoid overvoltage of the photovoltaic input interface 20, the circuit is simple, and the cost is reduced. In addition, the delay circuit 14 is respectively connected to the power supply circuit 11 and the comparison circuit 13. The delay circuit 14 is used to control the comparison circuit 13 to control the conduction or disconnection of the main switch circuit 15 according to the sampling voltage and the reference voltage when the second voltage is greater than or equal to the first preset voltage. That is, when the second voltage is less than the first preset voltage, the delay circuit 14 controls the main switch circuit 15 to remain disconnected through the comparison circuit 13, realizing delayed start-up, and avoiding the main switch circuit 15 from being damaged due to serious heating in the amplification region for a long time after being conducted when the second voltage is less than the first preset voltage. In addition, by arranging the main switch circuit 15 on the second line 22, it is applicable to high-power energy storage power supplies 1, without the need to find a switching tube with a smaller internal resistance, reducing the cost.

[0098] The above description is only the implementation mode of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. An overvoltage protection circuit, applied to an energy storage power supply, characterized in that: The energy storage power supply includes at least one photovoltaic input interface, and the photovoltaic input interface is used to connect to the MPPT circuit in the energy storage power supply. The photovoltaic input interface includes a high voltage end and a low voltage end. The high voltage end is connected to the MPPT circuit through a first line, and the low voltage end is connected to the MPPT circuit through a second line. The overvoltage protection circuit includes: a power supply circuit, connected between the first line and the second line, for converting the first voltage of the photovoltaic input interface into a second voltage, and outputting a reference voltage according to the second voltage; a sampling circuit connected between the first circuit and the second circuit; A comparison circuit, wherein a first input terminal of the comparison circuit is connected to the power supply circuit and receives the second voltage and the reference voltage from the power supply circuit, and a second input terminal of the comparison circuit is connected to the sampling circuit and receives a sampling voltage; A main switch circuit is arranged on the second line, and the output end of the comparison circuit is connected to the main switch circuit; A delay circuit is connected to the power supply circuit and the comparison circuit respectively, and the delay circuit is used to control the comparison circuit to control the conduction or disconnection of the main switch circuit according to the sampling voltage and the reference voltage when the second voltage is greater than or equal to the first preset voltage.

2. The overvoltage protection circuit according to claim 1, characterized in that: The delay circuit is used to output a first level to the comparison circuit when the second voltage is less than the first preset voltage, and the comparison circuit is used to control the main switch circuit to remain disconnected when receiving the first level; The delay circuit is used for outputting a second level to the comparison circuit when the second voltage is greater than or equal to the first preset voltage; The comparison circuit is used to control the main switch circuit to be turned on when the second level is received and the sampling voltage is less than or equal to the reference voltage, or the comparison circuit is used to control the main switch circuit to be turned off when the second level is received and the sampling voltage is greater than the reference voltage.

3. The overvoltage protection circuit according to claim 1, characterized in that: The delay circuit includes a current limiting unit, a first voltage stabilizing unit, a first switch unit and a voltage dividing unit, wherein a first end of the first voltage stabilizing unit and a first end of the first switch unit are connected to the power supply circuit through the current limiting unit, a first end of the first voltage stabilizing unit and a first end of the first switch unit are connected to an enable end of the comparison circuit, a control end of the first switch unit is connected to the voltage dividing unit, a first end of the voltage dividing unit is connected to the power supply circuit, and a second end of the first voltage stabilizing unit, a second end of the first switch unit and a second end of the voltage dividing unit are all connected to the second line.

4. The overvoltage protection circuit according to claim 3, characterized in that: The delay circuit further includes a second voltage stabilizing unit and a filtering unit. The voltage dividing unit is connected to the power supply circuit via the second voltage stabilizing unit, and the control end of the first switch unit is connected to the voltage dividing unit via the filtering unit.

5. The overvoltage protection circuit according to claim 4, characterized in that: When the second voltage is less than the first preset voltage, the first switch unit is disconnected, the power supply circuit supplies power to the first voltage stabilizing unit through the current limiting unit, and the enable end of the comparison circuit receives the first level; or, when the second voltage is greater than or equal to the first preset voltage, the first switch unit is turned on, and the enable end of the comparison circuit receives the second level.

6. The overvoltage protection circuit according to claim 4, characterized in that: The first switch unit includes a first switch, the current limiting unit includes a first resistor, the first voltage stabilizing unit includes a first voltage stabilizing tube, the voltage dividing unit includes a third resistor and a fourth resistor, the second voltage stabilizing unit includes a second voltage stabilizing tube, the filtering unit includes a first capacitor and a second resistor, the first end of the first switch tube is connected to the power supply circuit through the first resistor, the negative electrode of the first voltage stabilizing tube and the enable end of the comparison circuit are connected to the first end of the first switch tube, and the control end of the first switch tube is connected to the power supply circuit through the second resistor, the third resistor and the second voltage stabilizing tube; one end of the first capacitor and one end of the fourth resistor are connected between the second resistor and the third resistor, and the positive electrode of the first voltage stabilizing tube, the other end of the first capacitor, the other end of the fourth resistor and the second end of the first switch tube are grounded.

7. The overvoltage protection circuit according to any one of claims 1 to 6, characterized in that: The main switch circuit includes a drive circuit and a second switch tube, the second switch tube is arranged on the second line, the output end of the comparison circuit is connected to the control end of the second switch tube through the drive circuit, the comparison circuit is used to output a second level to the drive circuit when the sampling voltage is greater than the reference voltage, and the drive circuit is used to control the second switch tube to be disconnected when receiving the second level.

8. The overvoltage protection circuit according to claim 7, characterized in that: The comparison circuit is used to output a first level to the driving circuit when the sampling voltage is less than or equal to the reference voltage, and the driving circuit is used to control the second switch tube to be turned on when receiving the first level; wherein a turn-on speed at which the driving circuit controls the second switch tube to be turned on is greater than a turn-off speed at which the driving circuit controls the second switch tube to be turned off.

9. The overvoltage protection circuit according to claim 7, characterized in that: The power supply circuit includes a voltage stabilizing circuit and a reference voltage circuit. The voltage stabilizing circuit is connected between the first circuit and the second circuit and is used to convert the first voltage into the second voltage. The reference voltage circuit is respectively connected to the voltage stabilizing circuit and the comparison circuit and is used to output the reference voltage according to the second voltage.

10. The overvoltage protection circuit according to claim 9, characterized in that: The comparison circuit includes a comparator and a voltage stabilizing unit, wherein the first input terminal of the comparator is connected to the reference voltage circuit, the first power supply terminal of the comparator is connected to the voltage stabilizing circuit, the enable terminal of the comparator is connected to the delay circuit, the second input terminal of the comparator is connected to the sampling circuit, and the output terminal of the comparator is connected to the first input terminal of the comparator through the voltage stabilizing unit and is connected to the main switch circuit.

11. The overvoltage protection circuit according to claim 10, characterized in that: The driving circuit includes a fifth resistor, a sixth resistor, a seventh resistor and a first diode, wherein the anode of the first diode and one end of the sixth resistor are connected to the output end of the comparator through the fifth resistor, the cathode of the first diode and the other end of the sixth resistor are connected to the control end of the second switch tube, one end of the seventh resistor is connected to the second line, and the other end of the seventh resistor is connected to the control end of the second switch tube.

12. The overvoltage protection circuit according to claim 11, characterized in that: The voltage stabilizing unit includes a second capacitor, an eighth resistor and a ninth resistor, the output end of the comparator is connected to the first input end of the comparator through the eighth resistor, one end of the ninth resistor and one end of the second capacitor are connected to the first input end of the comparator, and the other end of the ninth resistor and the other end of the second capacitor are connected to the second circuit; The sampling circuit includes a tenth resistor and an eleventh resistor, the tenth resistor and the eleventh resistor are connected between the first circuit and the second circuit, and the second input terminal of the comparator is connected between the tenth resistor and the eleventh resistor.

13. The overvoltage protection circuit according to claim 12, characterized in that: The reference voltage circuit includes a third voltage regulator and a twelfth resistor, and the comparison circuit also includes a thirteenth resistor. The first end of the third voltage regulator is connected to the voltage regulator circuit through the twelfth resistor, the second end of the third voltage regulator is connected to the second circuit, the third end of the third voltage regulator is connected to the first end, and the first end of the third voltage regulator is connected to the second input end of the comparator through the thirteenth resistor.

14. The overvoltage protection circuit according to claim 13, characterized in that: The voltage stabilizing circuit includes a third switch tube, a fourth switch tube, a fourteenth resistor, a fifteenth resistor, a third capacitor, a fourth voltage stabilizing tube, a fourth capacitor and a fifth capacitor. The first end of the third switch tube and the first end of the fourth switch tube are connected to the first circuit through the fourteenth resistor, the second end of the third switch tube is connected to the twelfth resistor and the first power supply end of the comparator, the third end of the third switch tube is connected to the second end of the fourth switch tube, the third end of the fourth switch tube is connected to the second circuit through the fourth voltage stabilizing tube, one end of the fifteenth resistor is connected to the first end of the third switch tube, the other end of the fifteenth resistor and one end of the third capacitor are connected to the second end of the third switch tube, the other end of the third capacitor is connected to the second circuit, one end of the fourth capacitor and one end of the fifth capacitor are connected to the second end of the third switch tube, and the other end of the fourth capacitor and the other end of the fifth capacitor are connected to the second circuit.

15. An energy storage power supply, characterized in that: It includes at least one photovoltaic input interface, an MPPT circuit, and an overvoltage protection circuit as described in any one of claims 1 to 14, wherein the photovoltaic input interface is used to connect to the MPPT circuit, the photovoltaic input interface includes a high voltage end and a low voltage end, the high voltage end is connected to the MPPT circuit through a first line, the low voltage end is connected to the MPPT circuit through a second line, and the overvoltage protection circuit is connected between the first line and the second line.

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