Energy storage system direct current unit with reliable overcurrent protection and energy storage system

Abstract

The utility model provides an energy storage system direct current unit with reliable overcurrent protection and an energy storage system, and belongs to the technical field of overvoltage protection, the energy storage system direct current unit comprises a battery cluster, at least one fuse and an overvoltage protection device, the at least one fuse is connected in series in a direct current loop formed by the battery cluster, and the overvoltage protection device is connected in series with the at least one fuse. And the overvoltage protection device is connected in the direct current loop in parallel and is used for inhibiting overvoltage generated at the fusing moment of the at least one fuse. Compared with the prior art that an over-current fault loop is difficult to cut off due to over-voltage at the fusing moment of a fuse, the over-voltage protection device is arranged in the direct current unit of the energy storage system, is connected in the direct current loop in parallel, and is used for inhibiting the over-voltage generated at the fusing moment of the fuse, so that the over-current fault loop is prevented from being cut off due to the over-voltage at the fusing moment. The risk that after the fuse is fused, electric arc reignition occurs and fusing fails can be effectively reduced or even eliminated, and reliable over-current protection of the direct current unit is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of overvoltage protection, and particularly relates to a reliable overcurrent protection DC unit of an energy storage system and an energy storage system. BACKGROUND

[0002] The overcurrent protection of the DC unit of the energy storage system in the battery usually adopts a fuse, and specifically, the fuse is connected in series in a DC loop. When overcurrent or short-circuit fault occurs in the DC unit of the energy storage system, the fault current flows through the fuse. If the fault current reaches the fuse threshold of the fuse, the fuse is blown to disconnect the fault current loop of the DC unit of the energy storage system, thereby avoiding or reducing the risk of thermal runaway of the battery caused by long-time overcurrent of the DC unit of the energy storage system.

[0003] However, since filter devices such as inductors and capacitors usually exist in the AC-DC coupling circuit in the DC unit of the energy storage system, overvoltage several times higher than the DC voltage appears at both ends of the breaking point of the fuse at the moment of disconnection of the fuse. Under the action of such high overvoltage, there is a risk of arc reignition at the breaking point of the fuse. Once arc reignition occurs, the fuse fails, the fault current loop cannot be disconnected, and the battery faces a great risk of losing control.

[0004] Therefore, how to reduce or even eliminate the risk of arc reignition and fuse failure after the fuse is blown is a technical problem to be solved. CONTENT OF THE INVENTION

[0005] In view of the above technical problems, the embodiments of the application provide a reliable overcurrent protection DC unit of an energy storage system and an energy storage system, which can effectively reduce or even eliminate the risk of arc reignition and fuse failure after the fuse is blown, and realize reliable overcurrent protection of the DC unit.

[0006] In a first aspect, the embodiments of the application provide a reliable overcurrent protection DC unit of an energy storage system, which comprises a battery cluster, at least one fuse and an overvoltage protection device. The at least one fuse is connected in series in a DC loop formed by the battery cluster. The overvoltage protection device is connected in parallel in the DC loop and is used to suppress overvoltage generated by the at least one fuse at the moment of blowing.

[0007] Compared with the moment when the fuse in the related art is fused due to overcurrent, since filter devices such as inductors and capacitors usually exist in the load circuit, the devices cause a high overvoltage to appear at both ends of the break of the fuse, and further cause the break of the fuse to have arc reignition, which is difficult to effectively cut off the fault loop of overcurrent. In the technical solution of the embodiments of the present application, an overvoltage protection device is arranged in the direct current unit of the energy storage system, the overvoltage protection device is connected in parallel in the direct current loop, is used to suppress the overvoltage generated by at least one fuse at the moment of fusing, can effectively reduce or even eliminate the risk of arc reignition to fusing failure of the fuse after fusing, and realizes reliable overcurrent protection of the direct current unit.

[0008] In some embodiments, the overvoltage protection device includes at least one of a capacitor and an overvoltage protector.

[0009] In the embodiments of the present application, the overvoltage protection device can include a capacitor and / or an overvoltage protector, the capacitor and the overvoltage protector are simple to arrange and can reliably suppress the overvoltage at both ends of the fuse, thereby reducing or even eliminating the risk of arc reignition to fusing failure of the fuse after fusing.

[0010] In some embodiments, in the direct current loop, the capacitor is connected in parallel to the at least one fuse.

[0011] In the embodiments of the present application, a specific implementation mode of connecting the capacitor in parallel in the direct current loop is provided. Specifically, the capacitor can be connected in parallel on both sides of at least one fuse in the direct current loop. In normal operation, the fuse is turned on, and at this time, the voltage across the parallel capacitor is approximately equal to zero. When a short circuit fault occurs in the loop where the fuse is located, the fuse is fused in a very short time, and an overvoltage appears at both ends of the break of the fuse. At this time, the voltage across the capacitor starts to charge from zero, and the overvoltage at the break of the fuse is clamped, thereby achieving the purpose of avoiding arc reignition caused by too high overvoltage at the break of the fuse, and effectively improving the reliability of overcurrent protection of the direct current unit of the energy storage system.

[0012] In some embodiments, the parasitic inductance of the capacitor is lower than a preset value.

[0013] In the embodiments of the present application, a specific implementation mode of selecting a capacitor is provided. The capacitor with a relatively low parasitic inductance (specifically lower than a preset value) is connected in parallel on both sides of the fuse, the influence of the parasitic inductance on the overvoltage limitation is reduced, and the risk of arc reignition to fusing failure of the fuse after fusing is further reduced.

[0014] In some embodiments, the rated voltage of the capacitor is greater than the maximum direct current voltage of the battery cluster, and the capacitance of the capacitor is greater than the transient energy when the fuse is fused.

[0015] In the embodiments of the present application, a specific implementation of the capacitor is provided. The rated voltage of the capacitor in parallel should be greater than the maximum DC voltage of the battery cluster, and the capacitance should be large enough to absorb the transient energy when the fuse is blown, thereby achieving the purpose of limiting the overvoltage level, thereby reducing or even eliminating the risk of arc reignition to fuse failure after the fuse is blown.

[0016] In some embodiments, in the DC circuit, the overvoltage protector is connected in parallel with the at least one fuse.

[0017] In the embodiments of the present application, a specific implementation of the overvoltage protector connected in parallel in the DC circuit is provided. Specifically, the overvoltage protector can be connected in parallel on both sides of at least one fuse in the DC circuit. In normal operation, the fuse is on, and at this time the voltage across the parallel overvoltage protector is approximately equal to zero. When a short circuit fault occurs in the circuit where the fuse is located, the fuse is blown in a very short time, and an overvoltage occurs across the break of the fuse and the overvoltage protector. When the overvoltage reaches the protection level, the overvoltage protector acts to limit the overvoltage across the break of the fuse below the protection level, thereby achieving the purpose of avoiding arc reignition caused by too high overvoltage across the break of the fuse, and effectively improving the reliability of the overcurrent protection of the DC unit of the energy storage system.

[0018] In some embodiments, the overvoltage protector is connected in parallel between the total positive and the total negative of the DC circuit.

[0019] In the embodiments of the present application, a specific implementation of the overvoltage protector connected in parallel in the DC circuit is provided. Specifically, the overvoltage protector can be connected in parallel between the total positive and the total negative of the DC circuit. In normal operation, the fuse is on, and at this time the voltage across the parallel overvoltage protector is approximately equal to the total voltage on the DC side. When a short circuit fault occurs in the circuit where the fuse is located, the fuse is blown in a very short time, and at this time the voltage across the break of the fuse is approximately equal to the voltage between the total positive and the total negative of the DC circuit. When the voltage between the total positive and the total negative of the DC circuit reaches the protection level, the overvoltage protector acts to limit the overvoltage across the break of the fuse below the protection level, thereby achieving the purpose of avoiding arc reignition caused by too high overvoltage across the break of the fuse, and effectively improving the reliability of the overcurrent protection of the DC unit of the energy storage system.

[0020] In some embodiments, the overvoltage protector includes at least one of a varistor, a metal oxide arrester (MOA), and a transient suppression diode.

[0021] In the embodiments of the present application, a specific implementation of the overvoltage protector is provided. The overvoltage protector can include a varistor, an MOA, and a transient suppression diode, and a suitable overvoltage protector can be selected according to the actual circuit needs to suppress the overvoltage across the fuse.

[0022] In some embodiments, the DC loop of the energy storage system DC unit is used to supply power to an AC-DC coupling circuit, which includes a first contactor, a second contactor, a first resistor, a second resistor, a third resistor, a filter inductor, a filter capacitor, and a converter.

[0023] The first contactor, the first resistor, the filter inductor, and the converter are connected in series to form a main loop of the AC-DC coupling circuit, one end of the first contactor and one end of the converter are used as an input end of the AC-DC coupling circuit, the second contactor is connected in parallel to a branch formed by the first contactor and the first resistor in series, the filter capacitor is connected in parallel to the converter, and a branch formed by the second resistor and the third resistor in series is also connected in parallel to the converter.

[0024] In the embodiments of the present application, a specific implementation of a load circuit powered by an energy storage system DC unit is provided. The specific load circuit can be an AC-DC coupling circuit, which includes a filter inductor and a filter capacitor. When a fuse is blown, overvoltage is generated at both ends of the broken part of the fuse to release energy in the load circuit. When the load circuit connected to the DC unit is an AC-DC coupling circuit, the DC unit can effectively reduce the overvoltage generated by the AC-DC coupling circuit when the fuse is blown, thereby effectively reducing or even eliminating the risk of arc reignition after the fuse is blown, improving the reliability of the overcurrent protection of the energy storage system DC unit and the AC-DC coupling circuit, and further improving the reliability and safety of the battery using the DC unit and the AC-DC coupling circuit.

[0025] In some embodiments, the output end of the DC loop is connected to the input end of the AC-DC coupling circuit through at least one isolating switch.

[0026] In the embodiments of the present application, a specific implementation of the connection between the energy storage system DC unit and the AC-DC coupling circuit is provided. By setting an isolating switch, the energy storage system DC unit as a power supply and the AC-DC coupling circuit as a load can be isolated to protect personnel and equipment safety.

[0027] In a second aspect, the embodiments of the present application also provide an energy storage system, which includes at least one reliable overcurrent protection energy storage system DC unit and an AC-DC coupling circuit according to any of the above embodiments.

[0028] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, the embodiments can be implemented according to the content of the specification, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or related description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0030] Figure 1 is a schematic diagram of a fault current loop and related fuses in the related art;

[0031] Figure 2 is a schematic diagram of an energy storage system in the related art;

[0032] Figure 3 is a schematic diagram of a fuse blown type overvoltage in the related art;

[0033] Figure 4 is one of the structural schematic diagrams of a reliable overcurrent protection DC unit of an energy storage system according to an embodiment of the present application;

[0034] Figure 5 is another of the structural schematic diagrams of a reliable overcurrent protection DC unit of an energy storage system according to an embodiment of the present application;

[0035] Figure 6 is a third of the structural schematic diagrams of a reliable overcurrent protection DC unit of an energy storage system according to an embodiment of the present application;

[0036] Figure 7 is one of the structural schematic diagrams of an energy storage system according to an embodiment of the present application;

[0037] Figure 8 is another of the structural schematic diagrams of an energy storage system according to an embodiment of the present application;

[0038] Figure 9 is a third of the structural schematic diagrams of an energy storage system according to an embodiment of the present application. DETAILED DESCRIPTION

[0039] The embodiments of the technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of the terms "including," "comprising," or "having" and variations thereof herein is intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof. Unless otherwise required by context, singular terms shall include pluralities and vice versa. Unless otherwise required by context, the use herein of the singular is also to be construed as a use of the plural and vice versa.

[0041] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is two and more than two, unless otherwise explicitly and specifically limited.

[0042] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to each other. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0043] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0044] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups).

[0045] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connecting", "connecting", "fixing" and the like should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanical connection, or it can be electrical connection; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0046] In the related art, the overcurrent protection of the direct current unit of the energy storage system in the battery usually adopts a fuse. Specifically, the fuse is connected in series in the direct current loop. When an overcurrent or short circuit fault occurs in the direct current unit of the energy storage system, the fault current will flow through the fuse. If the fault current reaches the fuse threshold of the fuse, the fuse will be blown to disconnect the fault current loop of the direct current unit of the energy storage system, thereby avoiding or reducing the risk of thermal runaway of the battery caused by long-time overcurrent of the direct current unit of the energy storage system.

[0047] Figure 1 is a schematic diagram of the fault current loop and the fuse involved in the related art. As shown in Figure 1 , in the circuit (a) in the figure, one end of the battery cluster is connected to one end of the fuse 1 in a fault (for example, short circuit) connection. If the current I in the fault current loop is too large, the fuse 1 will be blown to disconnect the fault current loop. In the circuit (b) in the figure, one end of the battery cluster is connected to one end of the fuse 3 arranged inside the battery cluster in a fault (for example, short circuit) connection. If the current I in the fault current loop is too large, the fuse 3 will be blown to disconnect the fault current loop.

[0048] Usually, overcurrent fusing can be directly performed by using the fuse. However, in the energy storage system, filter devices such as inductors and capacitors often exist in the load circuit connected to the back of the direct current unit, Figure 2 is a schematic diagram of the energy storage system in the related art. As shown in Figure 2 , the load circuit includes filter devices such as filter inductors and filter capacitors. When the fuse is disconnected, the filter devices such as inductors and capacitors will instantaneously release a large amount of energy, so that an overvoltage several times higher than the direct current voltage (that is, the battery cluster voltage) appears at both ends of the disconnection of the fuse, Figure 3 is a schematic diagram of the overvoltage of the fuse blowing type in the related art. As shown in Figure 3 , at the moment of blowing of the fuse, the voltage U at both ends of the fuse even exceeds 6000V. Under the action of such a high overvoltage, there is a risk of arc reignition at both ends of the disconnection of the fuse. Once the arc reignition occurs, the fuse blowing fails, the fault current loop cannot be disconnected, and the battery will face a great risk of out-of-control.

[0049] To solve the above problems, the embodiments of the present application provide a reliable overcurrent protection energy storage system direct current unit and an energy storage system, which aims to limit the overvoltage level of the fuse at the moment of blowing, thereby eliminating or reducing the risk of arc reignition to fuse blowing failure after the fuse is blown, and improving the reliability of overcurrent protection.

[0050] The reliable overcurrent protection energy storage system direct current unit will be described in detail below. Figure 4 is one of the structure schematic diagrams of the reliable overcurrent protection energy storage system direct current unit proposed by the embodiments of the present application. As shown in Figure 4As shown, the DC unit of the energy storage system comprises: a battery cluster 10, at least one fuse 20 connected in series in a DC loop formed by the battery cluster 10, and an overvoltage protection device 30 connected in parallel in the DC loop for suppressing overvoltage generated by the at least one fuse 20 at the moment of fusing.

[0051] It should be noted that, Figure 4 In the foregoing embodiment, the DC unit of the energy storage system comprises two fuses 20, but the present application is not limited thereto, and one or more fuses 20 can be provided in the DC loop according to actual conditions.

[0052] In the technical solution of the embodiment of the present application, compared with the problem in the related art that, at the moment of fusing of the fuse due to overcurrent, due to the presence of filter devices such as inductors and capacitors in the load circuit, these devices cause a high overvoltage to appear at both ends of the breaking point of the fuse, and thus arc reignition occurs at the breaking point of the fuse, making it difficult to effectively cut off the fault circuit with overcurrent, the overvoltage protection device 30 is provided in the DC unit of the energy storage system, the overvoltage protection device 30 is connected in parallel in the DC loop for suppressing overvoltage generated by the at least one fuse 20 at the moment of fusing, which can effectively reduce or even eliminate the risk of arc reignition to fusing failure after the fuse 20 fuses, and thus reliable overcurrent protection of the DC unit is achieved.

[0053] In some embodiments, the overvoltage protection device 30 can comprise at least one of a capacitor and an overvoltage protector.

[0054] In the embodiment of the present application, a specific implementation of the overvoltage protection device 30 is provided. The overvoltage protection device 30 can comprise a capacitor and / or an overvoltage protector, which is simple to set up but can reliably suppress overvoltage at both ends of the fuse, thereby reducing or even eliminating the risk of arc reignition to fusing failure after the fuse fuses.

[0055] In some embodiments, a specific implementation of the capacitor C1 connected in parallel in the DC loop is provided. As shown in Figure 4 In the DC loop, the capacitor C1 is connected in parallel to the at least one fuse 20.

[0056] It should be noted that, Figure 4 In the foregoing embodiment, the overvoltage protection device 30 is implemented by the capacitor C1, and both fuses 20 are connected in parallel with the capacitor C1.

[0057] It should also be noted that the same or different capacitors C1 can be provided for the two fuses 20 according to actual conditions, and different capacitors C1 have different parameter values such as corresponding rated voltage, parasitic inductance, and capacitance.

[0058] In the embodiments of the present application, the capacitor C1 can be connected in parallel on both sides of at least one fuse 20 in the DC circuit. In normal operation, the fuse 20 is on, and at this time, the voltage across the parallel capacitor C1 is approximately equal to zero. When a short circuit fault occurs in the circuit where the fuse 20 is located, the fuse 20 is blown in a very short time, and an overvoltage appears across the break of the fuse 20. At this time, the voltage across the capacitor C1 starts to charge from zero, and the overvoltage across the break of the fuse 20 is clamped, thereby achieving the purpose of avoiding the arc reignition caused by too high overvoltage across the break of the fuse 20, and effectively improving the reliability of the overcurrent protection of the DC unit of the energy storage system.

[0059] In some embodiments, a specific implementation of selecting the capacitor C1 is provided. The parasitic inductance of the capacitor C1 is lower than a preset value.

[0060] It should be noted that the size of the preset value can be selected according to actual conditions. The smaller the preset value is, the smaller the parasitic inductance of the selected capacitor C1 is, and the smaller the influence of the parasitic inductance on the absorption of the overvoltage of the capacitor C1 to the fuse 20 is.

[0061] In the embodiments of the present application, the capacitor C1 with a relatively low parasitic inductance (specifically lower than a preset value) can be connected in parallel on both sides of the fuse 20, thereby reducing the influence of the parasitic inductance on the overvoltage limitation and further reducing the risk of arc reignition to fuse failure after the fuse 20 is blown.

[0062] In some embodiments, a specific implementation of selecting the capacitor C1 is provided. The rated voltage of the capacitor C1 is greater than the maximum DC voltage of the battery cluster 10, and the capacitance of the capacitor C1 is greater than the transient energy when the fuse 20 is blown.

[0063] It should be noted that the transient energy when the fuse 20 is blown can be obtained through relevant experiments, tests, etc., and the present application does not limit this.

[0064] In the embodiments of the present application, the rated voltage of the selected parallel capacitor C1 should be greater than the maximum DC voltage of the battery cluster 10, and the capacitance should be large enough to absorb the transient energy when the fuse 20 is blown, thereby achieving the purpose of limiting the overvoltage level, and thereby reducing or even eliminating the risk of arc reignition to fuse failure after the fuse 20 is blown.

[0065] In some embodiments, a specific implementation of connecting the overvoltage protector 301 in parallel in the DC circuit is provided. Figure 5 is a second structural schematic diagram of a reliable overcurrent protection DC unit of an energy storage system proposed in the embodiments of the present application. Figure 5As shown, in the direct current loop, the overvoltage protector 301 is connected in parallel with the at least one fuse 20.

[0066] It should be noted that, Figure 5 For example, in the energy storage system direct current unit, the overvoltage protector 301 is implemented by the overvoltage protection device 30, and the two fuses 20 are both connected in parallel with the overvoltage protector 301.

[0067] In the embodiments of the present application, the overvoltage protector 301 can be connected in parallel on both sides of the at least one fuse 20 in the direct current loop. In normal operation, the fuse 20 is conductive, and at this time, the voltage across the parallel overvoltage protector 301 is approximately equal to zero. When a short circuit fault occurs in the loop where the fuse 20 is located, the fuse 20 is fused in a very short time, and an overvoltage occurs across the break of the fuse 20 and the overvoltage protector 301. When the overvoltage reaches the protection level, the overvoltage protector 301 acts to limit the overvoltage across the break of the fuse 20 below the protection level, thereby avoiding the purpose of arc reignition caused by too high overvoltage across the break of the fuse 20, and effectively improving the reliability of the overcurrent protection of the energy storage system direct current unit.

[0068] In some embodiments, a specific implementation of the overvoltage protector 301 is provided. The overvoltage protector 301 can include at least one of a varistor, a MOA (Metal Oxide Arrester), and a transient suppression diode. Figure 5 For example, the overvoltage protector 301 is implemented by a varistor.

[0069] In the embodiments of the present application, the overvoltage protector 301 can include a varistor, a MOA, and a transient suppression diode, and a suitable overvoltage protector can be selected according to the actual circuit needs to suppress the overvoltage across the fuse.

[0070] For example, for a varistor, its main feature is that its resistance value changes with the change of the applied voltage, and when the applied voltage exceeds a certain threshold value, the resistance value will sharply decrease to form a low-resistance current path. In the application of the present application, after the fuse 20 is fused in a very short time, the voltage across the varistor exceeds the threshold value corresponding to the varistor, at which time the resistance value of the varistor sharply decreases to form a low-resistance current path to limit the voltage across the fuse 20.

[0071] It should be noted that when setting the related parameters of the varistor, the threshold value corresponding to the varistor, the resistance value after the decrease, the rated working voltage, and the like can be set according to the actual situation, and the present application does not limit this.

[0072] In some embodiments, according to actual conditions, a part of the plurality of overvoltage protection devices connected in parallel across the plurality of fuses can be set as capacitors, and another part can be set as overvoltage protectors, such as a voltage-dependent resistor, etc.

[0073] In some embodiments, a specific implementation of providing an overvoltage protector 301 in parallel in a DC circuit is provided. Figure 6 is a structure diagram of a reliable overcurrent protection energy storage system DC unit according to an embodiment of the present application. Figure 6 As shown, the overvoltage protector 301 is connected in parallel between the total positive and the total negative of the DC circuit.

[0074] It should be noted that, Figure 6 In the above embodiment, the energy storage system DC unit includes two fuses 20, and the overvoltage protection device 30 is implemented by the overvoltage protector 301.

[0075] In the embodiment of the present application, the overvoltage protector 301 can be connected in parallel between the total positive and the total negative of the DC circuit. In normal operation, the fuse 20 is conductive, and at this time, the voltage across the overvoltage protector 301 is approximately equal to the total voltage of the DC side. When a short circuit fault occurs in the circuit where the fuse 20 is located, the fuse 20 is fused in a very short time, and at this time, the voltage across the break of the fuse 20 is approximately equal to the voltage between the total positive and the total negative of the DC circuit. When the voltage between the total positive and the total negative of the DC circuit reaches the protection level, the overvoltage protector 301 acts to limit the overvoltage of the break of the fuse 20 below the protection level, thereby achieving the purpose of avoiding the arc reignition caused by too high overvoltage of the break of the fuse 20, and effectively improving the reliability of the overcurrent protection of the energy storage system DC unit.

[0076] In some embodiments, Figure 7 is one of the structure diagrams of an energy storage system according to an embodiment of the present application. Figure 7 As shown, the DC circuit of the energy storage system DC unit is used to supply power to an AC-DC coupling circuit, and the AC-DC coupling circuit includes a first contactor 40, a second contactor 50, a first resistor R1, a second resistor R2, a third resistor R3, a filter inductor L1, a filter capacitor C2, and a converter 60.

[0077] The first contactor 40, the first resistor R1, the filter inductor L1 and the current transformer 60 are connected in series to form a main loop of the AC-DC coupling circuit, one end of the first contactor 40 not connected and one end of the current transformer 60 not connected are used as input ends of the AC-DC coupling circuit, the second contactor 50 is connected in parallel to a branch formed by the first contactor 40 and the first resistor R1 in series, the filter capacitor C2 is connected in parallel to the current transformer 60, and a branch formed by the second resistor R2 and the third resistor R3 in series is also connected in parallel to the current transformer 60.

[0078] It should be noted that, Figure 7 In the embodiment, the capacitor C1 is connected in parallel on both sides of the fuse 20, and the current transformer 60 is composed of four switching devices, but the application is not limited to the specific arrangement of the current transformer 60, and any circuit that can realize the current transformation function can be applied.

[0079] In the embodiment, a specific implementation of a load circuit powered by a DC unit of an energy storage system is provided. The specific load circuit can be an AC-DC coupling circuit, which includes a filter inductor L1 and a filter capacitor C2. When the fuse 20 is blown, the filter inductor L1 and the filter capacitor C2 can generate an overvoltage at both ends of the broken part of the fuse 20 to release the energy in the load circuit. When the load circuit connected to the DC unit is an AC-DC coupling circuit, the DC unit of the application can effectively reduce the overvoltage of the AC-DC coupling circuit when the fuse 20 is blown, thereby effectively reducing or even eliminating the risk of arc reignition after the fuse 20 is blown, improving the reliability of the overcurrent protection of the DC unit of the energy storage system and the AC-DC coupling circuit, and further improving the reliability and safety of the battery using the DC unit and the AC-DC coupling circuit.

[0080] In some embodiments, a specific implementation of the connection between the DC unit of the energy storage system and the AC-DC coupling circuit is provided. As shown in Figure 7 The output end of the DC loop can be connected to the input end of the AC-DC coupling circuit through at least one isolation switch 70.

[0081] It should be noted that, Figure 7 In the embodiment, the two output ends of the DC loop are connected to the two input ends of the AC-DC coupling circuit through one isolation switch 70 respectively.

[0082] In the embodiment, by setting the isolation switch 70, the energy storage system DC unit as a power supply and the AC-DC coupling circuit as a load can be isolated to protect the safety of personnel and equipment.

[0083] The following examples illustrate the reliable overcurrent protection DC unit of the energy storage system provided by the application. The reliable overcurrent protection DC unit of the energy storage system mainly includes the following schemes:

[0084] (I) connecting the fuse 20 in parallel with a capacitor C1 with lower parasitic inductance;

[0085] Specifically, on the basis of Figure 2 , keeping other circuit topologies unchanged, only connecting a capacitor C1 with lower parasitic inductance in parallel with the fuse 20 can obtain Figure 7 . As shown in Figure 7 , at the moment when the fuse 20 is fused, the capacitor C1 absorbs the transient energy of the fault current loop, thereby reducing the overvoltage level at both ends of the fuse 20.

[0086] It should be noted that the rated voltage of the parallel capacitor C1 should be greater than the maximum DC voltage of the battery cluster 10, and the capacitance should be large enough to absorb the transient energy at the moment when the fuse 20 is fused, thereby limiting the overvoltage level.

[0087] Specifically, in normal operation, the fuse 20 is conductive, and the voltage across the parallel capacitor C1 is approximately equal to zero; when a short circuit fault occurs in the loop where the fuse 20 is located, the fuse 20 is fused in a very short time, and overvoltage occurs at the break of the fuse 20, at this time, the voltage across the capacitor C1 starts to charge from zero, clamping the overvoltage at the break of the fuse 20, thereby achieving the purpose of avoiding the arc reignition caused by too high overvoltage at the break of the fuse 20.

[0088] (II) connecting the fuse 20 in parallel with an overvoltage protector 301;

[0089] Specifically, on the basis of Figure 2 , keeping other circuit topologies unchanged, only connecting a voltage-dependent resistor in parallel with the fuse 20 can obtain Figure 8 . Figure 8 is a second structural diagram of an energy storage system according to an embodiment of the present application, as shown in Figure 8 , the overvoltage protector 301 can be but is not limited to a voltage-dependent resistor, at the moment when the fuse 20 is fused, the overvoltage protector 301 acts, limiting the overvoltage level at both ends of the fuse 20.

[0090] Specifically, in normal operation, the fuse 20 is conductive, and the voltage across the overvoltage protector 301 is approximately equal to zero; when a short circuit fault occurs in the loop where the fuse 20 is located, the fuse 20 is fused in a very short time, and overvoltage occurs at the break of the fuse 20 and at both ends of the overvoltage protector 301, when the overvoltage reaches the protection level, the overvoltage protector 301 acts, limiting the overvoltage at the break of the fuse 20 below the protection level, thereby achieving the purpose of avoiding the arc reignition caused by too high overvoltage at the break of the fuse 20.

[0091] (III) In parallel between the total positive and the total negative of the DC side (i.e. the above-mentioned DC circuit) including the fuse, a over-voltage protector 301 is arranged.

[0092] Specifically, on the basis of the above-mentioned circuit topology, the over-voltage protector 301 is arranged in parallel between the total positive and the total negative of the DC side including the fuse 20, and the other circuit topologies remain unchanged, so that the over-voltage protector 301 is obtained. Figure 2 Figure 9 . Figure 9 is a structural schematic diagram of a third energy storage system according to an embodiment of the present application, as shown in Figure 9 The over-voltage protector 301 can be but is not limited to a voltage-dependent resistor. At the moment when the fuse 20 is fused, the over-voltage protector 301 acts to limit the over-voltage level at both ends of the fuse 20.

[0093] It should be noted that the over-voltage protector 301 needs to be arranged to safely absorb the transient energy at the moment when the fuse 20 is fused, and has a suitable rated voltage to ensure that after the over-voltage, the over-voltage protector 301 safely interrupts the current and the short-circuit circuit is reliably cut off.

[0094] Specifically, in normal operation, the fuse 20 is conductive, and the voltage across the over-voltage protector 301 is approximately equal to the total voltage of the DC side. When a short-circuit fault occurs in the circuit in which the fuse 20 is arranged, the fuse 20 is fused in a very short time, and the voltage across the fuse 20 is approximately equal to the voltage between the total positive and the total negative of the DC side. When the voltage between the total positive and the total negative of the DC side reaches the protection level, the over-voltage protector 301 acts to limit the over-voltage at the break of the fuse 20 below the protection level, thereby achieving the purpose of avoiding the arc reignition caused by too high over-voltage at the break of the fuse 20.

[0095] The present application has at least the following beneficial effects:

[0096] 1) The over-voltage level at both ends of the fuse at the moment when the fuse is fused is significantly reduced.

[0097] 2) The risk of failure of the fuse caused by arc reignition is greatly reduced.

[0098] On the other hand, the present application also provides an energy storage system, which comprises at least one reliable over-current protection energy storage system DC unit and an AC-DC coupling circuit according to any one of the above-mentioned embodiments.

[0099] ​The above-described embodiments are only used to illustrate the technical solutions of the present application, but not limit them; although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A reliable overcurrent-protected energy storage system DC unit, characterized by, The overvoltage protection device includes at least one of a capacitor and an overvoltage protector.

2. The reliably overcurrent-protected energy storage system DC unit of claim 1, wherein, The capacitor is connected in parallel with the at least one fuse in the direct current loop.

3. The reliably overcurrent-protected energy storage system DC unit of claim 2, wherein, The parasitic inductance of the capacitor is lower than a preset value.

4. The reliably overcurrent-protected energy storage system DC unit of claim 2 or 3, wherein, The rated voltage of the capacitor is greater than the maximum direct current voltage of the battery cluster, and the capacitance of the capacitor is greater than the transient energy when the fuse is blown.

5. The reliably overcurrent-protected energy storage system DC unit of claim 2 or 3, wherein, The overvoltage protector is connected in parallel between the total positive and the total negative of the direct current loop.

6. The reliably overcurrent-protected energy storage system DC unit of claim 2, wherein, The overvoltage protector includes at least one of a varistor, a metal oxide arrester (MOA), and a transient suppression diode.

7. The reliably overcurrent-protected energy storage system DC unit of claim 2, wherein, The direct current loop of the energy storage system direct current unit is used to supply power to an AC-DC coupling circuit, and the AC-DC coupling circuit includes a first contactor, a second contactor, a first resistor, a second resistor, a third resistor, a filter inductor, a filter capacitor, and a converter.

8. The reliably overcurrent-protected energy storage system DC unit of claim 6 or 7, wherein, The first contactor, the first resistor, the filter inductor, and the converter are connected in series to form a main loop of the AC-DC coupling circuit, one end of the first contactor and one end of the converter that are not connected serve as an input end of the AC-DC coupling circuit, the second contactor is connected in parallel with a branch formed by the first contactor and the first resistor in series, the filter capacitor is connected in parallel with the converter, and a branch formed by the second resistor and the third resistor in series is also connected in parallel with the converter.

9. The reliably overcurrent-protected energy storage system DC unit of claim 1, 2, 3, 6, or 7, wherein, An output end of the direct current loop is connected to the input end of the AC-DC coupling circuit through at least one disconnector. The application also provides an energy storage system including at least one reliable overcurrent protection energy storage system direct current unit and an AC-DC coupling circuit.

10. The reliably overcurrent-protected energy storage system DC unit of claim 9, wherein, ​ 11. An energy storage system characterized by, ​

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