Photovoltaic input protection circuit and energy storage system

Abstract

The utility model relates to the technical field of energy storage power supplies, in particular to a photovoltaic input protection circuit and an energy storage system, and the circuit comprises a comparison output module, an amplification driving module and a switch module. The comparison output module is connected with the amplification driving module, the amplification driving module is connected with the switch module, and the switch module is used for being connected with a photovoltaic input source and a load. The comparison output module is used for receiving a pre-charging signal and outputting a voltage signal with a corresponding amplitude based on the duty ratio of the pre-charging signal, and the pre-charging signal is a pulse signal of which the duty ratio is increased by a preset step length; the amplification driving module is used for amplifying the voltage signal so as to drive the switch module to work in a variable resistance current limiting state. After the working mode of the switch module is set in the variable resistance current limiting state by gradually increasing the duty ratio of the pre-charging signal, the current input into the load by the photovoltaic input source can be limited through the switch module, so that the load is prevented from being damaged by the large current output by the photovoltaic input source, and devices in the load are protected.

Description

[Technical field]

[0001] The utility model relates to the technical field of energy storage power supplies, and in particular to a photovoltaic input protection circuit and an energy storage system. [Background technology]

[0002] As one of the most popular new energy products, energy storage power supply has rich functions, among which photovoltaic input source (PV) charging is indispensable.

[0003] However, the existing photovoltaic charging circuit generally includes a pre-charging module, and the pre-charging module will charge the energy storage capacitor regardless of whether the photovoltaic charging circuit is working. In practical applications, the withstand voltage of each component in the existing photovoltaic charging circuit is generally not very large due to cost considerations. Therefore, when the photovoltaic input voltage is greater than the withstand voltage of each component, it will cause damage to each component, thereby damaging the PV charging function of the energy storage power supply.

[0004] If the pre-charging module in the photovoltaic charging circuit is removed, when the input voltage of the photovoltaic input source is large, there is a risk of large current shock and damage to circuit components when it is directly input into the charging circuit. [Contents of the utility model]

[0005] The embodiment of the utility model provides a photovoltaic input protection circuit and an energy storage system, aiming to solve the technical problem in the prior art that when there is no pre-charging module in the photovoltaic charging circuit, the input voltage of the photovoltaic input source will damage the components in the circuit.

[0006] In order to solve the above technical problems, a technical solution adopted by the embodiment of the utility model is: to provide a photovoltaic input protection circuit, the photovoltaic input protection circuit includes a comparison output module, an amplification drive module and a switch module;

[0007] The comparison output module is connected to the amplification drive module, the amplification drive module is connected to the switch module, and the switch module is also used to connect to the photovoltaic input source and the load respectively;

[0008] The comparison output module is used to receive a pre-charge signal and output a voltage signal of a corresponding amplitude based on the duty cycle of the pre-charge signal, wherein the pre-charge signal is a pulse signal whose duty cycle increases with a preset step length;

[0009] The amplifying and driving module is used to amplify the voltage signal to drive the switch module to operate in a variable resistance and current limiting state.

[0010] Optionally, the comparison output module includes a control unit and an energy storage unit;

[0011] The control end of the control unit is used to receive the pre-charge signal, the output end of the control unit is connected to the energy storage unit, and the energy storage unit is connected to the amplification drive module;

[0012] The control unit is used for outputting a voltage signal to charge the energy storage unit when the pre-charge signal is at a high level, so that the energy storage unit stores a voltage signal of a corresponding amplitude.

[0013] Optionally, the control unit includes a switch tube Q16, a switch tube Q14, a resistor R9, a resistor R10, a resistor R12 and an operational amplifier U1;

[0014] The control end of the switch tube Q16 is connected to the controller, the first end of the switch tube Q16 is connected to the first voltage through the resistor R9, the first end of the switch tube Q16 is also connected to the control end of the switch tube Q14, the first end of the switch tube Q14 is connected to the first voltage through the resistor R10, the second end of the switch tube Q14 is connected to the in-phase input end of the operational amplifier U1 through the resistor R12, the inverting input end of the operational amplifier U1 is connected to the ground end, and the output end of the operational amplifier U1 is connected to the energy storage unit.

[0015] Optionally, the energy storage unit includes a capacitor C5 and a resistor R13;

[0016] The first end of the resistor R13 is connected to the output end of the operational amplifier U1 , the second end of the resistor R13 is respectively connected to the first end of the capacitor C5 and the amplifying driving module, and the second end of the capacitor C5 is grounded.

[0017] Optionally, the comparison output module further includes a discharge unit, wherein the discharge unit is a resistor R20;

[0018] The resistor R20 is connected in parallel with the capacitor C5.

[0019] Optionally, the amplifying driving module includes a transistor Q15 and a resistor R11;

[0020] The control end of the transistor Q15 is connected to the comparison output module, the first end of the transistor Q15 is connected to the control end of the switch module through the resistor R11, and the second end of the transistor Q15 is used for grounding.

[0021] Optionally, the switch module includes a resistor R8, a switch tube Q12 and a switch tube Q13;

[0022] The resistor R8 is respectively connected to the first end of the switch tube Q12 and the photovoltaic input source, the control end of the switch tube Q12 is respectively connected to the control end of the switch tube Q13, the resistor R8 and the amplification drive module, the second end of the switch tube Q12 is connected to the first end of the switch tube Q13, and the second end of the switch tube Q13 is used to be connected to the load.

[0023] Optionally, the switch module further includes a voltage regulator tube ZD2;

[0024] The voltage regulator tube ZD2 is connected in parallel with the resistor R8.

[0025] Optionally, the switch tube Q12 and the switch tube Q13 are field effect transistors.

[0026] In order to solve the above technical problems, another technical solution adopted by the embodiment of the utility model is: to provide an energy storage system, the energy storage system comprising:

[0027] Controller;

[0028] Photovoltaic input source;

[0029] load; and

[0030] The photovoltaic input protection circuit as described above, wherein the controller is connected to the control end of the photovoltaic input protection circuit, the photovoltaic input source is connected to the input end of the photovoltaic input protection circuit, and the output end of the photovoltaic input protection circuit is connected to the load.

[0031] Different from the related art, the utility model provides a photovoltaic input protection circuit and energy storage system, the photovoltaic input protection circuit includes a comparison output module, an amplification drive module and a switch module; the comparison output module is connected to the amplification drive module, the amplification drive module is connected to the switch module, and the switch module is also used to connect to the photovoltaic input source and the load respectively. The comparison output module is used to receive a pre-charge signal, and output a voltage signal of corresponding amplitude based on the duty cycle of the pre-charge signal, wherein the pre-charge signal is a pulse signal whose duty cycle increases with a preset step length; the amplification drive module is used to amplify the voltage signal to drive the switch module to work in a variable resistance current limiting state. Among them, since the photovoltaic input source supplies power to the load through the switch module, after gradually increasing the duty cycle of the pre-charge signal to set the working mode of the switch module in the variable resistance current limiting state, the switch module can be used to limit the current input from the photovoltaic input source to the load, thereby preventing the large current output by the photovoltaic input source from damaging the load, thereby protecting the devices in the load.

Brief Description of the Drawings

[0032] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and the figures in the drawings do not constitute proportional limitations unless otherwise stated.

[0033] Figure 1 It is a structural block diagram of an energy storage system provided by an embodiment of the utility model;

[0034] Figure 2 It is a structural block diagram of a photovoltaic input protection circuit provided by an embodiment of the utility model;

[0035] Figure 3 It is a circuit diagram of a photovoltaic input protection circuit provided by an embodiment of the utility model;

[0036] Figure 4 It is a schematic diagram of the voltage relationship between the pre-charge signal and the capacitor C5 provided by the embodiment of the utility model;

[0037] Figure 5 It is a circuit diagram of an energy storage system provided by an embodiment of the utility model. [Specific implementation method]

[0038] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0039] The technical features involved in the various embodiments of the present application described below do not conflict with each other and can be combined with each other.

[0040] When an element is referred to as being “connected to” another element, it can be directly connected to the other element, or one or more intervening elements may be present therebetween.

[0041] The terms "first", "second", etc. in the specification and claims of the present utility model are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more.

[0042] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not used to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more related listed items.

[0043] See also Figure 1 , Figure 1 is a structural block diagram of an energy storage system provided by an embodiment of the utility model, such as Figure 1 As shown, the energy storage system 1 includes a photovoltaic input source 100, a load 200, a photovoltaic input protection circuit 300 and a controller 400; the photovoltaic input protection circuit 300 is connected to the photovoltaic input source 100 and the load 200 respectively, and the photovoltaic input protection circuit 300 is also used to connect to the controller 400, and the controller 400 is also connected to the photovoltaic input source 100. Specifically, the photovoltaic input source 100 is used to charge the load 200 through the photovoltaic input protection circuit 300, and the controller 400 is used to detect the input voltage of the photovoltaic input source 100, and when the input voltage meets the preset range, output a pre-charge signal to the photovoltaic input protection circuit 300, so that the photovoltaic input source 300 completes the pre-charge of the load 200 based on the pre-charge signal. Wherein, the pre-charge refers to the process of charging the capacitor in the load (such as a capacitive load) at the initial stage of power-on. In this embodiment, during the pre-charge period, the drive switch module is operated in a variable resistance current limiting state to play the role of pre-charging resistance and limit the large current generated by the capacitor at the initial stage of power-on.

[0044] It should be noted that the photovoltaic input protection circuit 300 is turned on based on the pre-charge signal. When the photovoltaic input protection circuit 300 receives the pre-charge signal, the photovoltaic input protection circuit 300 starts to be turned on, and the input voltage can be input to the load 200 through the photovoltaic input protection circuit 300. The pre-charge signal is a pulse signal whose duty cycle increases with a preset step length. After the photovoltaic input protection circuit 300 pre-charges the load 200 based on the pulse signal, as the duty cycle of the pulse signal continues to increase, the photovoltaic input protection circuit 300 will be in a normal conduction state. At this time, the photovoltaic input source 100 will charge the load 200 through the photovoltaic input protection circuit 300.

[0045] In some embodiments, if the input voltage of the photovoltaic input source 100 is not within the preset range, the controller 400 stops outputting the pre-charge signal, thereby controlling the photovoltaic input protection circuit 300 to stop working, thereby protecting the load 200 .

[0046] For further information, see Figure 2 , Figure 2 is a structural block diagram of a photovoltaic input protection circuit provided by an embodiment of the utility model, such as Figure 2 As shown, the photovoltaic input protection circuit 300 includes a comparison output module 31, an amplification drive module 32 and a switch module 33; the comparison output module 31 is connected to the amplification drive module 32, the amplification drive module 32 is connected to the switch module 33, and the switch module 33 is also used to connect to the photovoltaic input source 100 and the load 200 respectively.

[0047] The comparison output module 31 is used to receive a pre-charge signal and output a voltage signal of a corresponding amplitude based on the duty cycle of the pre-charge signal, wherein the pre-charge signal is a pulse signal whose duty cycle increases with a preset step length;

[0048] The amplifying and driving module 32 is used to amplify the voltage signal to drive the switch module 33 to operate in a variable resistance and current limiting state.

[0049] Further, such as Figure 2 As shown, the comparison output module 31 includes a control unit 311 and an energy storage unit 312; the control end of the control unit 311 is used to receive the pre-charge signal, the output end of the control unit 311 is connected to the energy storage unit 312, and the energy storage unit 312 is connected to the amplification drive module 32;

[0050] The control unit 311 is used for outputting a voltage signal to charge the energy storage unit 312 when the pre-charge signal is at a high level, so that the energy storage unit 312 stores a voltage signal of a corresponding amplitude.

[0051] Specifically, when the input voltage is within the preset range, the controller 400 will output a pre-charge signal to the control unit 311. When the control unit 311 receives the pre-charge signal, it will charge the energy storage unit 312 based on the duty cycle of the pre-charge signal, so that the energy storage unit 312 stores a voltage signal with an amplitude corresponding to the duty cycle of the pulse signal. At this time, the control end of the amplification drive module 32 will conduct and amplify the voltage signal based on the voltage signal stored in the energy storage unit 312, and output the amplified voltage signal to the switch module 33 to drive the switch module 33 to start working. It should be noted that, when the duty cycle of the pre-charge signal continues to increase, the voltage output by the amplifying driving module 32 also continues to increase, and the voltage received by the switch module 33 also continues to increase. At this time, the switch module 33 also changes from the cut-off state to the variable resistance current limiting state and then to the on state. When the switch module 33 operates in the variable resistance current limiting state, the photovoltaic input source 100 will slowly output the voltage to the load 200 through the switch module 33 to complete the pre-charging of the load 200; after the pre-charging is completed, the switch module 33 operates in the on state, and the photovoltaic input source 100 begins to charge the load 200 normally through the switch module 33.

[0052] Among them, see Figure 3 , Figure 3 is a circuit diagram of a photovoltaic input protection circuit provided by an embodiment of the utility model, such as Figure 3 As shown, the control unit 311 includes a switch tube Q16, a switch tube Q14, a resistor R9, a resistor R10, a resistor R12 and an operational amplifier U1; the energy storage unit 312 includes a capacitor C5 and a resistor R13;

[0053] The control end of the switch tube Q16 is connected to the controller 400, the first end of the switch tube Q16 is connected to the first voltage through the resistor R9, the first end of the switch tube Q16 is also connected to the control end of the switch tube Q14, the first end of the switch tube Q14 is connected to the first voltage through the resistor R10, the second end of the switch tube Q14 is connected to the in-phase input end of the operational amplifier U1 through the resistor R12, the inverting input end of the operational amplifier U1 is connected to the ground end, and the output end of the operational amplifier U1 is connected to the energy storage unit 312.

[0054] The first end of the resistor R13 is connected to the output end of the operational amplifier U1 , the second end of the resistor R13 is respectively connected to the first end of the capacitor C5 and the amplifying driving module 32 , and the second end of the capacitor C5 is grounded.

[0055] Specifically, when the controller 400 outputs a pulse signal, the switch tube Q16 is turned on based on the high level in the pulse signal. When the switch tube Q16 is turned on, the switch tube Q14 is also turned on. At this time, the first voltage is input to the same-direction input terminal of the operational amplifier U1 through the resistor R10, the switch tube Q14 and the resistor R12. After receiving the high level, the operational amplifier U1 outputs the high level to the capacitor C5 to charge the capacitor C5. Figure 4 As shown, as the duty cycle of the pulse signal increases, the electric energy stored in the capacitor C5 also increases. Among them, the frequency of the pulse signal, the duty cycle range and the preset step size can be adjusted according to demand. For example, when the input voltage is small (within the preset range), in order to avoid wasting the input voltage of the photovoltaic input source 100, it is necessary to charge the load 200 as soon as possible. At this time, the preset step size can be set to be longer to reduce the time when the switch module 33 works in the variable resistance current limiting state.

[0056] In some embodiments, Figure 2 As shown, the comparison output module 31 also includes a discharge unit 313, and the discharge unit 313 is connected in parallel with the capacitor C5. Specifically, in this embodiment, the discharge unit 313 is used to discharge the electric energy stored in the capacitor C5 when the comparison output module 31 does not receive the pre-charge signal, that is, when the comparison output module 31 continues to output a low-level signal, or when the control end of the switch tube Q16 continues to receive a low-level signal, so as to ensure that the photovoltaic input protection circuit 300 can normally pre-charge the load 200 after the photovoltaic input is powered off and then powered on again. Figure 3 As shown, the discharge unit 313 is a resistor R20, and the resistor R20 is connected in parallel with the capacitor C5.

[0057] Further, such as Figure 3 As shown, the amplification driving module 32 includes a transistor Q15 and a resistor R11; the control end of the transistor Q15 is connected to the comparison output module 31, the first end of the transistor Q15 is connected to the control end of the switch module 33 through the resistor R11, and the second end of the transistor Q15 is used for grounding.

[0058] The switch module 33 includes a resistor R8, a switch tube Q12 and a switch tube Q13; the resistor R8 is respectively connected to the first end of the switch tube Q12 and the photovoltaic input source 100, the control end of the switch tube Q12 is respectively connected to the control end of the switch tube Q13, the resistor R8 and the amplification driving module 32, the second end of the switch tube Q12 is connected to the first end of the switch tube Q13, and the second end of the switch tube Q13 is used to connect to the load 200.

[0059] In some embodiments, the switch tube Q12 and the switch tube Q13 are field effect transistors.

[0060] Specifically, the transistor Q15 is a current-type device (i.e., a current-amplifying device), and the field effect transistor is a voltage-type device (i.e., a voltage-amplifying device). When the electric energy stored in the capacitor C5 increases continuously, the state of the transistor Q15 will also change from a cut-off state (equivalent to a high-impedance state) → an amplified state (a variable resistance region) → a saturated state (a conductive state). When the voltage in the capacitor C5 increases continuously, the current at the control end of the transistor Q15 also increases continuously, so that the current at the first end of the transistor Q15 also gradually increases. When the current at the first end of the transistor Q15 increases continuously, the voltage drop across the resistor R8 also increases continuously, so that the switch tube Q12 and the switch tube Q13 change from a cut-off state (equivalent to a high-impedance state) → an amplified state (a variable resistance region) → a saturated state (a conductive state), thereby causing the photovoltaic input source 100 to start charging the load 200 through the switch tube Q12 and the switch tube Q13. It should be noted that when the switch tube Q12 and the switch tube Q13 are changed from the cut-off state to the amplification state, the internal resistance of the switch tube Q12 and the switch tube Q13 also gradually decreases from infinity, so that the input voltage is slowly input into the load 200, thereby slowly charging the load 200 (that is, completing the pre-charging). In other words, when the switch tube Q12 and the switch tube Q13 are in the amplification state (variable resistance current limiting state), the pre-charging function of the load 200 can be completed without the need to set up an additional pre-charging circuit.

[0061] Furthermore, when the duty cycle of the pre-charge signal increases continuously, the control terminal voltage of the transistor Q15 also increases continuously, and the driving voltage of the control terminal of the switch tube Q12 and the switch tube Q13 also increases continuously. At this time, if the transistor Q15 enters the saturation state first, then no matter whether the voltage stored in the capacitor C5 increases or not, the current at the first end of the transistor Q15 will not change, so that the voltage drop across the resistor R8 will not change, that is, the driving voltage of the switch tube Q12 and the switch tube Q13 will not change, and the internal resistance of the switch tube Q12 and the switch tube Q13 will not change, so that the photovoltaic input source 100 can stably charge the load 200 through the switch tube Q12 and the switch tube Q13. If the switch tube Q12 and the switch tube Q13 enter the saturation state first, then no matter whether the voltage drop across the resistor R8 increases, the internal resistance of the switch tube Q12 and the switch tube Q13 will not change, so that the photovoltaic input source 100 stably charges the load 200 through the switch tube Q12 and the switch tube Q13. If the transistor Q15 and the switch tubes Q12 and Q13 enter the saturation state at the same time, then no matter whether the voltage stored in the capacitor C5 increases, the current at the first end of the transistor Q15 will not change, the internal resistance of the switch tube Q12 and the switch tube Q13 will not change, and the internal resistance of the switch tube Q12 and the switch tube Q13 is the minimum value, so that the photovoltaic input source 100 stably charges the load 200 through the switch tube Q12 and the switch tube Q13.

[0062] In some embodiments, the switch module 33 further includes a voltage regulator ZD2, and the voltage regulator ZD2 is connected in parallel with the resistor R8. The voltage regulator ZD2 is a clamping diode, which is mainly used to protect the switch tube Q12 and the switch tube Q13 from being damaged when the input voltage of the photovoltaic input source 100 is too large. Specifically, when the input voltage is too large, that is, when the voltage across the resistor R8 is greater than the voltage regulation value of the voltage regulator diode ZD2, the voltage regulator ZD2 is broken down. At this time, the voltage across the resistor R8 is the voltage regulation value of the voltage regulator ZD2, thereby protecting the switch tube Q12 and the switch tube Q13.

[0063] In some embodiments, the switch tube Q13 is also used to prevent reverse connection. Specifically, when the photovoltaic input source 100 is reversely connected, due to the presence of the body diode in the switch tube Q13, the input voltage of the photovoltaic input source 100 does not form a loop, thereby protecting the load 200.

[0064] The utility model provides a photovoltaic input protection circuit, which includes a comparison output module, an amplification drive module and a switch module; the comparison output module is connected to the amplification drive module, the amplification drive module is connected to the switch module, and the switch module is also used to connect to the photovoltaic input source and the load respectively. The comparison output module is used to receive a pre-charge signal, and output a voltage signal of corresponding amplitude based on the duty cycle of the pre-charge signal, wherein the pre-charge signal is a pulse signal whose duty cycle increases with a preset step length; the amplification drive module is used to amplify the voltage signal to drive the switch module to work in a variable resistance current limiting state. Among them, since the photovoltaic input source supplies power to the load through the switch module, after gradually increasing the duty cycle of the pre-charge signal to set the working mode of the switch module in the variable resistance current limiting state, the switch module can be used to limit the current input from the photovoltaic input source to the load, thereby avoiding the large current output by the photovoltaic input source from damaging the load, thereby protecting the devices in the load.

[0065] See also Figure 5 , Figure 5 is a circuit diagram of an energy storage system provided by an embodiment of the utility model, such as Figure 5 As shown, the load 200 is a photovoltaic charging circuit, wherein the photovoltaic charging circuit includes a pre-charge capacitor C6, a buck-boost module (switch tube Q19, switch tube Q20, switch tube Q22, switch tube Q25 and inductor L3) and an energy storage power supply (BAT+). When the photovoltaic input protection circuit 300 is connected to the photovoltaic charging circuit and the photovoltaic input source 100 respectively, the controller 400 will first detect whether the input voltage of the photovoltaic input source 100 is within a preset range. If so, the pre-charge signal is sent to the switch tube Q16 to control the on and off of the switch tube Q16. In the process of increasing the duty cycle of the pre-charge signal, the voltage received by the control end of the transistor Q15 also increases continuously, and the driving voltage received by the control end of the switch tube Q12 and the switch tube Q13 also gradually increases, and the internal resistance also gradually decreases from infinity. Based on this, the internal resistance change when the switch tube Q12 and the switch tube Q13 are turned on can be used to limit the current charging the pre-charge capacitor C6, thereby realizing the pre-charging function, and after the pre-charging is completed, the energy storage power supply starts to be charged.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Under the idea of ​​the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A photovoltaic input protection circuit, characterized in that: The photovoltaic input protection circuit includes a comparison output module, an amplification drive module and a switch module; The comparison output module is connected to the amplification drive module, the amplification drive module is connected to the switch module, and the switch module is also used to connect to the photovoltaic input source and the load respectively; The comparison output module is used to receive a pre-charge signal and output a voltage signal of a corresponding amplitude based on the duty cycle of the pre-charge signal, wherein the pre-charge signal is a pulse signal whose duty cycle increases with a preset step length; The amplifying and driving module is used to amplify the voltage signal to drive the switch module to operate in a variable resistance and current limiting state.

2. The photovoltaic input protection circuit according to claim 1, characterized in that: The comparison output module includes a control unit and an energy storage unit; The control end of the control unit is used to receive the pre-charge signal, the output end of the control unit is connected to the energy storage unit, and the energy storage unit is connected to the amplification drive module; The control unit is used for outputting a voltage signal to charge the energy storage unit when the pre-charge signal is at a high level, so that the energy storage unit stores a voltage signal of a corresponding amplitude.

3. The photovoltaic input protection circuit according to claim 2, characterized in that: The control unit includes a switch tube Q16, a switch tube Q14, a resistor R9, a resistor R10, a resistor R12 and an operational amplifier U1; The control end of the switch tube Q16 is connected to the controller, the first end of the switch tube Q16 is connected to the first voltage through the resistor R9, the first end of the switch tube Q16 is also connected to the control end of the switch tube Q14, the first end of the switch tube Q14 is connected to the first voltage through the resistor R10, the second end of the switch tube Q14 is connected to the in-phase input end of the operational amplifier U1 through the resistor R12, the inverting input end of the operational amplifier U1 is connected to the ground end, and the output end of the operational amplifier U1 is connected to the energy storage unit.

4. The photovoltaic input protection circuit according to claim 3, characterized in that: The energy storage unit includes a capacitor C5 and a resistor R13; The first end of the resistor R13 is connected to the output end of the operational amplifier U1 , the second end of the resistor R13 is respectively connected to the first end of the capacitor C5 and the amplifying driving module, and the second end of the capacitor C5 is grounded.

5. The photovoltaic input protection circuit according to claim 4, characterized in that: The comparison output module further includes a discharge unit, wherein the discharge unit is a resistor R20; The resistor R20 is connected in parallel with the capacitor C5.

6. The photovoltaic input protection circuit according to claim 1, characterized in that: The amplification driving module includes a transistor Q15 and a resistor R11; The control end of the transistor Q15 is connected to the comparison output module, the first end of the transistor Q15 is connected to the control end of the switch module through the resistor R11, and the second end of the transistor Q15 is used for grounding.

7. The photovoltaic input protection circuit according to claim 1, characterized in that: The switch module includes a resistor R8, a switch tube Q12 and a switch tube Q13; The resistor R8 is respectively connected to the first end of the switch tube Q12 and the photovoltaic input source, the control end of the switch tube Q12 is respectively connected to the control end of the switch tube Q13, the resistor R8 and the amplification drive module, the second end of the switch tube Q12 is connected to the first end of the switch tube Q13, and the second end of the switch tube Q13 is used to be connected to the load.

8. The photovoltaic input protection circuit according to claim 7, characterized in that: The switch module also includes a voltage regulator tube ZD2; The voltage regulator tube ZD2 is connected in parallel with the resistor R8.

9. The photovoltaic input protection circuit according to claim 7, characterized in that: The switch tube Q12 and the switch tube Q13 are field effect transistors.

10. An energy storage system, characterized in that: The energy storage system comprises: Controller; Photovoltaic input source; load; and The photovoltaic input protection circuit according to any one of claims 1 to 9, wherein the controller is connected to a control end of the photovoltaic input protection circuit, the photovoltaic input source is connected to an input end of the photovoltaic input protection circuit, and an output end of the photovoltaic input protection circuit is connected to the load.

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