Low-power-consumption power-lack protection circuit suitable for energy storage system

Abstract

The utility model discloses a low-power-consumption power-lack protection circuit suitable for an energy storage system, and relates to the technical field of energy storage systems. The circuit comprises a single-pole double-throw switch, an energy storage direct current side differential sampling circuit unit, a reference source circuit unit, an in-phase proportion operation amplification circuit unit, a hysteresis comparison circuit unit and a switch driving circuit unit, the normally-open end and the common end of the single-pole double-throw switch are used for being connected to the output end of a DC / DC module in a power supply of the energy storage system and the anode of a diode in a one-to-one correspondence mode, and through the communication connection relation, the single-pole double-throw switch can be switched off when the energy storage direct current side reaches a set power-lack protection point, and therefore the energy storage system can be protected. And at the moment, the energy storage direct current side only needs to consume a small amount of power, so that the loss can be reduced, the battery does not lack of electricity in a short time, the electricity lack phenomenon of the energy storage system is further prevented, and the service life of the battery is prolonged.

Description

Technical Field

[0001] The utility model belongs to the technical field of energy storage systems, and particularly relates to a low-power power shortage protection circuit applicable to energy storage systems. Background Technique

[0002] To achieve the dual-carbon goal (i.e., carbon peak and carbon neutrality), the country is vigorously developing low-carbon and green energy. As an important part of low-carbon energy, energy storage systems are widely used.

[0003] As Figure 1 shown, the power supply of the energy storage system is generally provided by an AC / DC module. When the AC / DC module has no output, the DC / DC module supplies power to the system. Among them, the power supply input of the AC / DC module has two sources: the 220VAC power supply of the external UPS (Uninterruptible Power Supply) and the 220VAC power supply of the external commercial power. The power supply input of the DC / DC module comes from the energy storage DC side of the energy storage system.

[0004] Since the power required by the power supply of the energy storage system is generally 50W, if the external commercial power of the owner is cut off and there is no external UPS 220VAC power supply, the power supply can only be provided by the DC / DC module at this time, resulting in a power shortage phenomenon on the energy storage DC side (also known as "Insufficient Voltage", which generally refers to a state of insufficient voltage and involves both the power supply and the electrical appliance; when the battery power is insufficient or the internal resistance of the power supply is too large, the electrical appliance cannot obtain the rated voltage for normal operation, and this state is called the power shortage phenomenon), affecting the battery life. Therefore, in order to prevent the power shortage phenomenon in the energy storage system and extend the service life of the battery, it is urgent to provide a low-power power shortage protection solution for the energy storage system. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a low-power power shortage protection circuit applicable to an energy storage system to prevent the power shortage phenomenon in the energy storage system and extend the service life of the battery.

[0006] To achieve the above purpose, the utility model adopts the following technical solutions:

[0007] In the first aspect, a low-power power shortage protection circuit applicable to an energy storage system is provided, including a single-pole double-throw switch, an energy storage DC side differential sampling circuit unit, a reference source circuit unit, a non-inverting proportional operation amplifier circuit unit, a hysteresis comparison circuit unit, and a switch drive circuit unit. Among them, the normally closed end of the single-pole double-throw switch is suspended, and the normally open end and the common end of the single-pole double-throw switch are used to be correspondingly connected to the output end of the DC / DC module in the power supply of the energy storage system and the anode of the diode.

[0008] The energy storage DC side differential sampling circuit unit is used to sample the voltage of the energy storage DC side of the energy storage system to obtain a sampled voltage;

[0009] The reference source circuit unit is used to provide a reference voltage;

[0010] The non-inverting proportional operation amplifier circuit unit includes a first operational amplifier, a first resistor, and a second resistor. Among them, the positive input terminal of the first operational amplifier is connected to the reference voltage output terminal of the reference source circuit unit, the negative input terminal of the first operational amplifier is respectively connected to one end of the first resistor and one end of the second resistor, the other end of the first resistor is grounded, the other end of the second resistor is connected to the output terminal of the first operational amplifier, and the output terminal of the first operational amplifier is used as the output terminal of the non-inverting proportional operation amplifier circuit unit;

[0011] The hysteresis comparison circuit unit includes a second operational amplifier, a third resistor, and a fourth resistor. Among them, the negative input terminal of the second operational amplifier is connected to the sampled voltage output terminal of the energy storage DC side differential sampling circuit unit, the positive input terminal of the second operational amplifier is respectively connected to one end of the third resistor and one end of the fourth resistor, the other end of the third resistor is connected to the output terminal of the non-inverting proportional operation amplifier circuit unit, the other end of the fourth resistor is connected to the output terminal of the second operational amplifier, and the output terminal of the second operational amplifier is used as the output terminal of the hysteresis comparison circuit unit;

[0012] The switch driving circuit unit is used to drive the single-pole double-throw switch to close the normally open end and the common end when the hysteresis comparison circuit unit outputs a low level, and to drive the single-pole double-throw switch to disconnect the normally open end and the common end when the hysteresis comparison circuit unit outputs a high level.

[0013] Based on the above-mentioned utility model content, a low-power energy storage system power shortage protection scheme is provided, which includes a single-pole double-throw switch, an energy storage DC side differential sampling circuit unit, a reference source circuit unit, a non-inverting proportional operation amplifier circuit unit, a hysteresis comparison circuit unit, and a switch driving circuit unit. Among them, the normally closed end of the single-pole double-throw switch is suspended, the normally open end and the common end of the single-pole double-throw switch are respectively connected to the output terminal of the DC / DC module in the power supply of the energy storage system and the anode of the diode. Through their communication connection relationship, when the power shortage protection point is reached on the energy storage DC side, the single-pole double-throw switch can be disconnected, that is, the power supply of the energy storage system is de-energized. At this time, only a small amount of power needs to be consumed on the energy storage DC side, so as to reduce losses, prevent the battery from losing power in a short time, and further prevent the energy storage system from experiencing a power shortage phenomenon, extend the service life of the battery, and facilitate practical application and promotion.

[0014] In a possible design, the energy storage DC side differential sampling circuit unit includes a third operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first capacitor, and a second capacitor. Among them, the fifth resistor and the sixth resistor have the same resistance value, and the seventh resistor and the eighth resistor have the same resistance value;

[0015] The positive input terminal of the third operational amplifier is respectively connected to one end of the sixth resistor, one end of the eighth resistor, and one end of the first capacitor. The other end of the sixth resistor is used to connect to the positive terminal of the energy storage DC side voltage of the energy storage system. The other ends of the eighth resistor and the first capacitor are respectively grounded;

[0016] The negative input terminal of the third operational amplifier is respectively connected to one end of the fifth resistor, one end of the seventh resistor, and one end of the second capacitor. The other end of the fifth resistor is used to connect to the negative terminal of the energy storage DC side voltage of the energy storage system. The other ends of the seventh resistor and the second capacitor are respectively connected to the output terminal of the third operational amplifier, and the output terminal of the third operational amplifier is used as the sampling voltage output terminal of the energy storage DC side differential sampling circuit unit.

[0017] In a possible design, the reference source circuit unit includes a ninth resistor and a programmable precision voltage reference of model TL431. Among them, one end of the ninth resistor is connected to the DC power supply, and the other end of the ninth resistor is respectively connected to the reference electrode and the cathode of the programmable precision voltage reference. The anode of the programmable precision voltage reference is grounded, and the cathode of the programmable precision voltage reference is used as the reference voltage output terminal of the reference source circuit unit.

[0018] In a possible design, the non-inverting proportional operational amplifier circuit unit further includes a tenth resistor, an eleventh resistor, and a third capacitor. Among them, the two ends of the tenth resistor are respectively and correspondingly connected to the reference voltage output terminal of the reference source circuit unit and the positive input terminal of the first operational amplifier, so as to realize that the positive input terminal of the first operational amplifier is connected to the reference voltage output terminal of the reference source circuit unit;

[0019] One end of the eleventh resistor and one end of the third capacitor are respectively connected to the positive input terminal of the first operational amplifier, and the other ends of the eleventh resistor and the third capacitor are respectively grounded.

[0020] In a possible design, the non-inverting proportional operational amplifier circuit unit further includes a fourth capacitor. Among them, the two ends of the fourth capacitor are respectively and correspondingly connected to the two ends of the second resistor.

[0021] In a possible design, the single-pole double-throw switch uses a relay, and the switch driving circuit unit includes an inverting circuit sub-unit, a twelfth resistor, a thirteenth resistor, a fifth capacitor, a triode, and a fourteenth resistor;

[0022] One end of the coil branch of the relay is used to connect to the output end of the DC / DC module, and the other end of the coil branch of the relay is connected to one end of the fourteenth resistor;

[0023] The input end of the inverting circuit sub-unit is connected to the output end of the hysteresis comparison circuit unit, the output end of the inverting circuit sub-unit is connected to one end of the twelfth resistor, the other end of the twelfth resistor is respectively connected to one end of the thirteenth resistor, one end of the fifth capacitor, and the base of the triode, the other ends of the thirteenth resistor, the fifth capacitor, and the emitter of the triode are respectively grounded, and the collector of the triode is connected to the other end of the fourteenth resistor.

[0024] In a possible design, the inverting circuit sub-unit includes a fourth operational amplifier, a fifteenth resistor, and a sixteenth resistor. Among them, the negative input terminal of the fourth operational amplifier is connected to one end of the fifteenth resistor, the positive input terminal of the fourth operational amplifier is connected to one end of the sixteenth resistor, the other end of the fifteenth resistor is used as the input end of the inverting circuit sub-unit, the other end of the sixteenth resistor is connected to the output end of the non-inverting proportional operational amplifier circuit unit, and the output end of the fourth operational amplifier is used as the output end of the inverting circuit sub-unit.

[0025] In a possible design, a low-pass filter circuit unit is connected in series between the negative input terminal of the second operational amplifier and the sampling voltage output terminal of the energy storage DC side differential sampling circuit unit.

[0026] In a possible design, the low-pass filter circuit unit includes a seventeenth resistor and a sixth capacitor. Among them, one end of the seventeenth resistor is respectively connected to the negative input terminal of the second operational amplifier and one end of the sixth capacitor, the other end of the seventeenth resistor is connected to the sampling voltage output terminal of the energy storage DC side differential sampling circuit unit, and the sixth capacitor is grounded.

[0027] In a possible design, a DC boost / buck circuit unit is further included. Among them, the DC boost / buck circuit unit includes a DC boost / buck chip, a first electrolytic capacitor, a second electrolytic capacitor, a seventh capacitor, and an eighth capacitor;

[0028] The input terminals of the DC step-up / step-down chip are respectively connected to the output terminal of the DC / DC module, the positive electrode of the first electrolytic capacitor, and one end of the seventh capacitor. The output terminal of the DC step-up / step-down chip is respectively connected to the positive electrode of the second electrolytic capacitor, one end of the eighth capacitor, the power supply terminal of the reference source circuit unit, and the power supply terminals of all operational amplifiers. The ground terminal of the DC step-up / step-down chip, the other pole of the first electrolytic capacitor, the other pole of the second electrolytic capacitor, the other end of the seventh capacitor, and the other end of the eighth capacitor are respectively grounded.

[0029] Advantages of the above solution:

[0030] (1) The present invention creatively provides a power loss protection solution for a low-power energy storage system, which includes a single-pole double-throw switch, a differential sampling circuit unit on the DC side of the energy storage, a reference source circuit unit, a non-inverting proportional operation amplifier circuit unit, a hysteresis comparison circuit unit, and a switch drive circuit unit. Among them, the normally closed terminal of the single-pole double-throw switch is suspended, and the normally open terminal and the common terminal of the single-pole double-throw switch are used to be correspondingly connected to the output terminal of the DC / DC module in the power supply of the energy storage system and the anode of the diode. Through their communication connection relationship, when the power loss protection point set on the DC side of the energy storage is reached, the single-pole double-throw switch can be disconnected, that is, the power supply of the energy storage system is de-energized. At this time, only a small amount of power needs to be consumed on the DC side of the energy storage, which can reduce the loss, prevent the battery from losing power in a short time, and further prevent the power loss phenomenon of the energy storage system, and extend the service life of the battery.

[0031] (2) This power loss protection solution also has the advantages of low loss, long battery service life, and flexible setting of the power loss voltage protection point and voltage recovery value, which is convenient for practical application and promotion. Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 It is a schematic circuit diagram of the power supply of the energy storage system provided by this application.

[0034] Figure 2 It is a schematic circuit diagram of a low-power power loss protection circuit applicable to an energy storage system provided by an embodiment of this application. Detailed Embodiments

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in conjunction with the accompanying drawings and the description of the embodiments or the prior art. Obviously, the following description of the structures of the drawings is only some embodiments of the present invention. For those of ordinary skill in the art, other embodiments can be obtained based on these embodiments without creative efforts. It should be noted here that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation to the present invention.

[0036] It should be understood that although terms such as first and second etc. may be used herein to describe various objects, these objects should not be limited by these terms. These terms are only used to distinguish one object from another. For example, the first object can be called the second object, and similarly, the second object can be called the first object, without departing from the scope of the exemplary embodiments of the present invention.

[0037] It should be understood that for the term "and / or" that may appear in this article, it is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, B exists alone, or A and B exist simultaneously; another example, A, B and / or C can represent any one of A, B and C or any combination of them; for the term " / and" that may appear in this article, it is a description of another association object relationship, indicating that two relationships can exist. For example, A / and B can represent two situations: A exists alone or A and B exist simultaneously; in addition, for the character " / " that may appear in this article, generally it represents that the front and rear associated objects are in an "or" relationship.

[0038] Embodiment

[0039] As Figure 2 shown, the low-power power-loss protection circuit provided in this embodiment and applicable to an energy storage system includes, but is not limited to, a single-pole double-throw switch K3, an energy storage DC-side differential sampling circuit unit, a reference source circuit unit, a non-inverting proportional operation amplifier circuit unit, a hysteresis comparison circuit unit, a switch drive circuit unit, etc. Among them, the normally closed end of the single-pole double-throw switch K3 is suspended, and the normally open end and the common end of the single-pole double-throw switch K3 are used to be correspondingly connected to the output end of the DC / DC module and the anode of the diode D1 in the power supply of the energy storage system. The DC / DC module and the diode D1 are conventional configurations of the power supply of the existing energy storage system. Refer to Figure 1 In Figure 2The output terminal of the DC / DC module is represented by +24V2, the output terminal of the AC / DC module in the existing energy storage system power supply is represented by +24V, the output terminal of the existing energy storage system power supply is represented by 24VDC, and another single-pole double-throw switch K1 is used to switch and control the output of the energy storage system power supply. Among them, K1 can be specifically implemented using existing relay products, and as Figure 2 shown, the on / off of K1 can be controlled by the button J2. In this way, after the button J2 is pressed, K1 conducts. If there is no input power to the AC / DC module, that is, +24V has no output, the energy storage system power supply can only be provided by closing K3 from the DC / DC module.

[0040] The energy storage DC-side differential sampling circuit unit is used to sample the energy storage DC-side voltage of the energy storage system to obtain a sampled voltage. Specifically, as Figure 2 shown, the energy storage DC-side differential sampling circuit unit includes, but is not limited to, the third operational amplifier U1C, the fifth resistor R9, the sixth resistor R10, the seventh resistor R15, the eighth resistor R16, the first capacitor C23, and the second capacitor C24, etc. Among them, the fifth resistor R9 and the sixth resistor R10 have the same resistance value, and the seventh resistor R15 and the eighth resistor R16 have the same resistance value; the positive input terminal of the third operational amplifier U1C is respectively connected to one end of the sixth resistor R10, one end of the eighth resistor R16, and one end of the first capacitor C23. The other end of the sixth resistor R10 is used to connect to the positive terminal BAT+ of the energy storage DC-side voltage of the energy storage system. The other ends of the eighth resistor R16 and the first capacitor C23 are respectively grounded; the negative input terminal of the third operational amplifier U1C is respectively connected to one end of the fifth resistor R9, one end of the seventh resistor R15, and one end of the second capacitor C24. The other end of the fifth resistor R9 is used to connect to the negative terminal BAT- of the energy storage DC-side voltage of the energy storage system. The other ends of the seventh resistor R15 and the second capacitor C24 are respectively connected to the output terminal of the third operational amplifier U1C. The output terminal of the third operational amplifier U1C is used as the sampled voltage output terminal of the energy storage DC-side differential sampling circuit unit. The first capacitor C23 and the second capacitor C24 are used to prevent the third operational amplifier U1C from generating self-oscillation.

[0041] The reference source circuit unit is used to provide a reference voltage. Specifically, the reference source circuit unit includes, but is not limited to, a ninth resistor R34 and a programmable precision voltage reference U2 of model TL431. Among them, one end of the ninth resistor R34 is connected to a DC power supply, and the other end of the ninth resistor R34 is respectively connected to the reference electrode and the cathode of the programmable precision voltage reference U2. The anode of the programmable precision voltage reference U2 is grounded, and the cathode of the programmable precision voltage reference U2 is used as the reference voltage output terminal of the reference source circuit unit.

[0042] The non-inverting proportional operation amplifier circuit unit includes, but is not limited to, a first operational amplifier U1A, a first resistor R32, and a second resistor R27. Among them, the positive input terminal of the first operational amplifier U1A is connected to the reference voltage output terminal of the reference source circuit unit. The negative input terminal of the first operational amplifier U1A is respectively connected to one end of the first resistor R32 and one end of the second resistor R27. The other end of the first resistor R32 is grounded, and the other end of the second resistor R27 is connected to the output terminal of the first operational amplifier U1A. The output terminal of the first operational amplifier U1A is used as the output terminal of the non-inverting proportional operation amplifier circuit unit. In addition, also in order to prevent the first operational amplifier U1A from generating self-oscillation, preferably, the non-inverting proportional operation amplifier circuit unit further includes, but is not limited to, a tenth resistor R26, an eleventh resistor R45, and a third capacitor C11. Among them, the two ends of the tenth resistor R26 are respectively and correspondingly connected to the reference voltage output terminal of the reference source circuit unit and the positive input terminal of the first operational amplifier U1A, so as to realize that the positive input terminal of the first operational amplifier U1A is connected to the reference voltage output terminal of the reference source circuit unit. One end of the eleventh resistor R45 and one end of the third capacitor C11 are respectively connected to the positive input terminal of the first operational amplifier U1A, and the other end of the eleventh resistor R45 and the other end of the third capacitor C11 are respectively grounded. And the non-inverting proportional operation amplifier circuit unit further includes a fourth capacitor C8, where the two ends of the fourth capacitor C8 are respectively and correspondingly connected to the two ends of the second resistor R27.

[0043] The hysteresis comparison circuit unit includes, but is not limited to, a second operational amplifier U1B, a third resistor R28, a fourth resistor R25, etc. Among them, the negative input terminal of the second operational amplifier U1B is connected to the sampling voltage output terminal of the energy storage DC side differential sampling circuit unit. The positive input terminal of the second operational amplifier U1B is respectively connected to one end of the third resistor R28 and one end of the fourth resistor R25. The other end of the third resistor R28 is connected to the output terminal of the non-inverting proportional operational amplifier circuit unit. The other end of the fourth resistor R25 is connected to the output terminal of the second operational amplifier U1B. The output terminal of the second operational amplifier U1B is used as the output terminal of the hysteresis comparison circuit unit.

[0044] The switch driving circuit unit is used to drive the single-pole double-throw switch K3 to close the normally open terminal and the common terminal when the hysteresis comparison circuit unit outputs a low level, and to drive the single-pole double-throw switch K3 to disconnect the normally open terminal and the common terminal when the hysteresis comparison circuit unit outputs a low level.

[0045] As Figure 2 shown, the working principle of the above low-power power shortage protection circuit specifically includes, but is not limited to, the following: If the sampling voltage V6 is greater than V5, then V7 is at a low level of 0V (at this time, the V5 voltage is the lower limit threshold V5L). The single-pole double-throw switch K3 can be driven by the switch driving circuit unit to close the normally open terminal and the common terminal, so that +24V2 can supply power to the energy storage system power supply 24VDC. As the sampling voltage V6 decreases, when the sampling voltage V6 is lower than the lower limit threshold V5L of V5, the level of V7 flips and becomes a high level (at this time, the V5 voltage is the upper limit threshold V5H). The single-pole double-throw switch K3 can be driven by the switch driving circuit unit to close the normally open terminal and the common terminal, so that +24V2 cannot supply power to the energy storage system power supply 24VDC (at this time, the energy storage converter needs to charge the energy storage system battery). As the sampling voltage V6 rises, when the sampling voltage V6 is higher than the upper limit threshold V5H of V5, the level of V7 flips again to become a low level, and the single-pole double-throw switch K3 can be driven again by the switch driving circuit unit to close the normally open terminal and the common terminal, so that +24V2 can supply power to the energy storage system power supply 24VDC again. In this way, when the energy storage system power supply can only be provided by the DC / DC module, if it has been supplied by the energy storage DC side all the time, when the power required by the energy storage system power supply is 50W, it can only last for 30 days, and by using Figure 2For the shown undercharged protection circuit, when the undercharged protection point (i.e., the lower limit threshold V5L) is reached on the DC side of the energy storage, K3 can be disconnected, that is, the 24VDC power supply of the energy storage system is de-energized. At this time, only 1W of power needs to be consumed on the DC side of the energy storage, which can reduce the loss, prevent the battery from being undercharged in a short time, and further prevent the energy storage system from experiencing an undercharged phenomenon, thus extending the service life of the battery.

[0046] The specific design of the above undercharged protection point can be achieved in the following way: According to the protection point of the undercharged voltage, select the resistance values of the first resistor R32 and the second resistor R27, and according to the difference between the undercharged voltage protection value and the recovery voltage threshold, select the resistance values of the third resistor R28 and the fourth resistor R25. Among them, the undercharged voltage protection value is the lower limit threshold V5L. The specific formula is as follows:

[0047]

[0048] In the formula, Vref represents the reference voltage; and the recovery voltage threshold is the upper limit threshold V5H. The specific formula is as follows:

[0049]

[0050] In the formula, VDD represents the voltage of the DC power supply, specifically 12V as an example. In this way, the resistance values of the third resistor R28 and the fourth resistor R25 can be selected using the difference between the undercharged voltage protection value and the recovery voltage threshold, and then the resistance values of the first resistor R32 and the second resistor R27 can be selected according to the undercharged voltage protection value. For example: Select R9 = R10 = 4490kΩ, R15 = R16 = 15kΩ, R45 = R26 = 1kΩ. The controllable precision voltage regulator U2 selects the 2.5V reference voltage output of TL431 (i.e., Vref is 2.5V), and calculates V6 = 0.00334×V5L; using the difference of 50V between the undercharged voltage protection value and the recovery voltage threshold, calculate R28 = 1.5kΩ and R25 = 100kΩ; according to the undercharged voltage protection value, calculate R27 = 620Ω and R32 = 1kΩ.

[0051] Preferably, the single-pole double-throw switch K3 is a relay. The switch driving circuit unit includes, but is not limited to, a reverse circuit sub-unit, a twelfth resistor R22, a thirteenth resistor R24, a fifth capacitor C9, a triode Q1, a fourteenth resistor R31, etc. One end of the coil branch of the relay is used to connect to the output end of the DC / DC module, and the other end of the coil branch of the relay is connected to one end of the fourteenth resistor R31. The input end of the reverse circuit sub-unit is connected to the output end of the hysteresis comparison circuit unit. The output end of the reverse circuit sub-unit is connected to one end of the twelfth resistor R22. The other end of the twelfth resistor R22 is respectively connected to one end of the thirteenth resistor R24, one end of the fifth capacitor C9, and the base of the triode Q1. The other ends of the thirteenth resistor R24, the fifth capacitor C9, and the emitter of the triode Q1 are respectively grounded. The collector of the triode Q1 is connected to the other end of the fourteenth resistor R31. Thus, through the specific design of the foregoing switch driving circuit, when the hysteresis comparison circuit unit outputs a low level, the single-pole double-throw switch K3 can be driven to close the normally open terminal and the common terminal, and when the hysteresis comparison circuit unit outputs a low level, the single-pole double-throw switch K3 can be driven to disconnect the normally open terminal and the common terminal. In addition, specifically, the reverse circuit sub-unit includes, but is not limited to, a fourth operational amplifier U1D, a fifteenth resistor R50, a sixteenth resistor R51, etc. Among them, the negative input terminal of the fourth operational amplifier U1D is connected to one end of the fifteenth resistor R50, the positive input terminal of the fourth operational amplifier U1D is connected to one end of the sixteenth resistor R51, the other end of the fifteenth resistor R50 is used as the input end of the reverse circuit sub-unit, the other end of the sixteenth resistor R51 is connected to the output end of the non-inverting proportional operational amplifier circuit unit, and the output end of the fourth operational amplifier U1D is used as the output end of the reverse circuit sub-unit.

[0052] Preferably, a low-pass filter circuit unit is connected in series between the negative input terminal of the second operational amplifier U1B and the sampling voltage output terminal of the energy storage DC side differential sampling circuit unit. Through the specific design of the low-pass filter circuit unit, AC signals can be filtered out, the fluctuation of the sampling voltage V6 can be reduced, and thus it is beneficial to perform stable on-off control on the single-pole double-throw switch K3. In addition, specifically, the low-pass filter circuit unit includes, but is not limited to, a seventeenth resistor R21 and a sixth capacitor C7. One end of the seventeenth resistor R21 is respectively connected to the negative input terminal of the second operational amplifier U1B and one end of the sixth capacitor C7. The other end of the seventeenth resistor R21 is connected to the sampling voltage output terminal of the energy storage DC side differential sampling circuit unit, and the sixth capacitor C7 is grounded.

[0053] Preferably, it further includes a DC boost / buck circuit unit. Among them, the DC boost / buck circuit unit includes, but is not limited to, a DC boost / buck chip U3, a first electrolytic capacitor C17, a second electrolytic capacitor C14, a seventh capacitor C16, and an eighth capacitor C13. The input end of the DC boost / buck chip U3 is respectively connected to the output end of the DC / DC module, the positive electrode of the first electrolytic capacitor C17, and one end of the seventh capacitor C16. The output end of the DC boost / buck chip U3 is respectively connected to the positive electrode of the second electrolytic capacitor C14, one end of the eighth capacitor C13, the power supply end of the reference source circuit unit, and the power supply terminals of all operational amplifiers. The ground end of the DC boost / buck chip U3, the other pole of the first electrolytic capacitor C17, the other pole of the second electrolytic capacitor C14, the other end of the seventh capacitor C16, and the other end of the eighth capacitor C13 are respectively grounded. As Figure 2 shown, the DC boost / buck circuit unit is used to boost or buck the direct current (generally 24V direct current) from the DC / DC module to the required direct current for the reference source circuit unit and all operational amplifiers (as Figure 2 shown, specifically 12V direct current). Among them, the DC boost / buck chip U3 can be implemented by using existing related chips.

[0054] In summary, adopting the low-power power shortage protection circuit provided by this embodiment has the following technical effects:

[0055] (1) This embodiment provides a low-power power shortage protection solution for the energy storage system, which includes a single-pole double-throw switch, an energy storage DC side differential sampling circuit unit, a reference source circuit unit, a non-inverting proportional operation amplifier circuit unit, a hysteresis comparison circuit unit, and a switch drive circuit unit. Among them, the normally closed end of the single-pole double-throw switch is suspended, and the normally open end and the common end of the single-pole double-throw switch are used to be respectively connected to the output end of the DC / DC module and the anode of the diode in the power supply of the energy storage system. Through their communication connection relationship, when the power shortage protection point set on the energy storage DC side is reached, the single-pole double-throw switch can be disconnected, that is, the power supply of the energy storage system is de-energized. At this time, only a small amount of power needs to be consumed on the energy storage DC side, so that the loss can be reduced, the battery will not be power-short in a short time, and further the power shortage phenomenon of the energy storage system can be prevented, and the service life of the battery can be extended;

[0056] (2) This power shortage protection solution also has the advantages of low loss, long battery service life, and flexible setting of the power shortage voltage protection point and voltage recovery value, which is convenient for practical application and promotion.

[0057] Finally, it should be noted that the above are only the preferred embodiments of the present utility model and are not intended to limit the protection scope of the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A low power consumption power failure protection circuit suitable for an energy storage system, characterized in that: The invention comprises a single-pole double-throw switch (K3), a differential sampling circuit unit on the DC side of an energy storage system, a reference source circuit unit, an in-phase proportional operational amplifier circuit unit, a hysteresis comparison circuit unit and a switch driving circuit unit, wherein the normally closed end of the single-pole double-throw switch (K3) is suspended, and the normally open end and the common end of the single-pole double-throw switch (K3) are used to be connected to the output end of a DC / DC module in a power supply of an energy storage system and the anode of a diode (D1) in a one-to-one correspondence; The energy storage DC side differential sampling circuit unit is used to sample the energy storage DC side voltage of the energy storage system to obtain a sampled voltage; The reference source circuit unit is used to provide a reference voltage; The in-phase proportional operational amplifier circuit unit comprises a first operational amplifier (U1A), a first resistor (R32) and a second resistor (R27), wherein the positive input terminal of the first operational amplifier (U1A) is connected to the reference voltage output terminal of the reference source circuit unit, the negative input terminal of the first operational amplifier (U1A) is respectively connected to one end of the first resistor (R32) and one end of the second resistor (R27), the other end of the first resistor (R32) is grounded, the other end of the second resistor (R27) is connected to the output terminal of the first operational amplifier (U1A), and the output terminal of the first operational amplifier (U1A) is used as the output terminal of the in-phase proportional operational amplifier circuit unit; The hysteresis comparison circuit unit comprises a second operational amplifier (U1B), a third resistor (R28) and a fourth resistor (R25), wherein the negative input terminal of the second operational amplifier (U1B) is connected to the sampling voltage output terminal of the energy storage DC side differential sampling circuit unit, the positive input terminal of the second operational amplifier (U1B) is respectively connected to one end of the third resistor (R28) and one end of the fourth resistor (R25), the other end of the third resistor (R28) is connected to the output end of the in-phase proportional operational amplifier circuit unit, the other end of the fourth resistor (R25) is connected to the output end of the second operational amplifier (U1B), and the output end of the second operational amplifier (U1B) is used as the output end of the hysteresis comparison circuit unit; The switch driving circuit unit is used for driving the single-pole double-throw switch (K3) to close the normally open end and the common end when the hysteresis comparison circuit unit outputs a low level, and for driving the single-pole double-throw switch (K3) to disconnect the normally open end and the common end when the hysteresis comparison circuit unit outputs a low level.

2. The low power consumption under-power protection circuit according to claim 1, characterized in that: The energy storage DC side differential sampling circuit unit comprises a third operational amplifier (U1C), a fifth resistor (R9), a sixth resistor (R10), a seventh resistor (R15), an eighth resistor (R16), a first capacitor (C23) and a second capacitor (C24), wherein the fifth resistor (R9) and the sixth resistor (R10) have the same resistance value, and the seventh resistor (R15) and the eighth resistor (R16) have the same resistance value; The positive input end of the third operational amplifier (U1C) is respectively connected to one end of the sixth resistor (R10), one end of the eighth resistor (R16) and one end of the first capacitor (C23); the other end of the sixth resistor (R10) is used to connect to the positive terminal (BAT+) of the energy storage DC side voltage of the energy storage system; the other end of the eighth resistor (R16) and the other end of the first capacitor (C23) are respectively grounded; The negative input terminal of the third operational amplifier (U1C) is respectively connected to one end of the fifth resistor (R9), one end of the seventh resistor (R15) and one end of the second capacitor (C24); the other end of the fifth resistor (R9) is used to connect to the negative terminal (BAT-) of the energy storage DC side voltage of the energy storage system; the other end of the seventh resistor (R15) and the other end of the second capacitor (C24) are respectively connected to the output end of the third operational amplifier (U1C); the output end of the third operational amplifier (U1C) is used as the sampling voltage output end of the energy storage DC side differential sampling circuit unit.

3. The low power consumption under-power protection circuit according to claim 1, characterized in that: The reference source circuit unit comprises a ninth resistor (R34) and a controllable precision voltage-stabilizing source (U2) of model TL431, wherein one end of the ninth resistor (R34) is connected to a DC power supply, and the other end of the ninth resistor (R34) is respectively connected to a reference electrode and a cathode of the controllable precision voltage-stabilizing source (U2), the anode of the controllable precision voltage-stabilizing source (U2) is grounded, and the cathode of the controllable precision voltage-stabilizing source (U2) is used as a reference voltage output end of the reference source circuit unit.

4. The low power consumption under-power protection circuit according to claim 1, characterized in that: The in-phase proportional operational amplifier circuit unit also includes a tenth resistor (R26), an eleventh resistor (R45) and a third capacitor (C11), wherein two ends of the tenth resistor (R26) are respectively connected to the reference voltage output end of the reference source circuit unit and the positive input end of the first operational amplifier (U1A) in a one-to-one correspondence, so as to realize that the positive input end of the first operational amplifier (U1A) is connected to the reference voltage output end of the reference source circuit unit; One end of the eleventh resistor (R45) and one end of the third capacitor (C11) are respectively connected to the positive input terminal of the first operational amplifier (U1A), and the other end of the eleventh resistor (R45) and the other end of the third capacitor (C11) are respectively grounded.

5. The low power consumption under-power protection circuit as claimed in claim 1, characterized in that: The in-phase proportional operational amplifier circuit unit also includes a fourth capacitor (C8), wherein two ends of the fourth capacitor (C8) are respectively connected to two ends of the second resistor (R27) in a one-to-one correspondence.

6. The low power consumption power failure protection circuit as claimed in claim 1, characterized in that: The single-pole double-throw switch (K3) adopts a relay, and the switch driving circuit unit includes a reverse circuit subunit, a twelfth resistor (R22), a thirteenth resistor (R24), a fifth capacitor (C9), a transistor (Q1) and a fourteenth resistor (R31); One end of the coil branch of the relay is used to connect to the output end of the DC / DC module, and the other end of the coil branch of the relay is connected to one end of the fourteenth resistor (R31); The input end of the reverse circuit subunit is connected to the output end of the hysteresis comparison circuit unit, the output end of the reverse circuit subunit is connected to one end of the twelfth resistor (R22), the other end of the twelfth resistor (R22) is respectively connected to one end of the thirteenth resistor (R24), one end of the fifth capacitor (C9) and the base of the transistor (Q1), the other end of the thirteenth resistor (R24), the other end of the fifth capacitor (C9) and the emitter of the transistor (Q1) are respectively grounded, and the collector of the transistor (Q1) is connected to the other end of the fourteenth resistor (R31).

7. The low power consumption power failure protection circuit as claimed in claim 6, characterized in that: The reverse circuit subunit includes a fourth operational amplifier (U1D), a fifteenth resistor (R50) and a sixteenth resistor (R51), wherein the negative input terminal of the fourth operational amplifier (U1D) is connected to one end of the fifteenth resistor (R50), the positive input terminal of the fourth operational amplifier (U1D) is connected to one end of the sixteenth resistor (R51), the other end of the fifteenth resistor (R50) is used as the input terminal of the reverse circuit subunit, the other end of the sixteenth resistor (R51) is connected to the output terminal of the in-phase proportional operational amplifier circuit unit, and the output terminal of the fourth operational amplifier (U1D) is used as the output terminal of the reverse circuit subunit.

8. The low power consumption under-power protection circuit as claimed in claim 1, characterized in that: A low-pass filter circuit unit is connected in series between the negative input terminal of the second operational amplifier (U1B) and the sampling voltage output terminal of the energy storage DC side differential sampling circuit unit.

9. The low power consumption power failure protection circuit as claimed in claim 8, characterized in that: The low-pass filter circuit unit comprises a seventeenth resistor (R21) and a sixth capacitor (C7), wherein one end of the seventeenth resistor (R21) is respectively connected to the negative input end of the second operational amplifier (U1B) and one end of the sixth capacitor (C7), the other end of the seventeenth resistor (R21) is connected to the sampling voltage output end of the energy storage DC side differential sampling circuit unit, and the sixth capacitor (C7) is grounded.

10. The low power consumption under-power protection circuit according to claim 1, characterized in that: It also includes a DC boost / buck circuit unit, wherein the DC boost / buck circuit unit includes a DC boost / buck chip (U3), a first electrolytic capacitor (C17), a second electrolytic capacitor (C14), a seventh capacitor (C16) and an eighth capacitor (C13); The input end of the DC boost / buck chip (U3) is respectively connected to the output end of the DC / DC module, the positive electrode of the first electrolytic capacitor (C17) and one end of the seventh capacitor (C16); the output end of the DC boost / buck chip (U3) is respectively connected to the positive electrode of the second electrolytic capacitor (C14), one end of the eighth capacitor (C13), the power supply end of the reference source circuit unit and the power supply ends of all operational amplifiers; the ground end of the DC boost / buck chip (U3), the other electrode of the first electrolytic capacitor (C17), the other electrode of the second electrolytic capacitor (C14), the other end of the seventh capacitor (C16) and the other end of the eighth capacitor (C13) are respectively grounded.

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