Energy storage capacity increasing device and energy storage system

Abstract

The utility model relates to the technical field of energy storage, and discloses an energy storage capacity increasing device and an energy storage system.The energy storage capacity increasing device comprises a new battery cluster, a first step-up and step-down circuit, a second step-up and step-down circuit and a high-voltage box; the new battery cluster and the old battery cluster are connected in parallel to the DC bus; wherein the new battery cluster is connected to the direct current bus through the high-voltage box, the first step-up and step-down circuit and the second step-up and step-down circuit in sequence; the first step-up and step-down circuit is reversely connected with the second step-up and step-down circuit, so that the voltage between the first step-up and step-down circuit and the voltage of the high-voltage box end form a voltage difference, and the voltage between the first step-up and step-down circuit and the voltage of the direct-current bus end form a voltage difference; according to the energy storage capacity increasing device, reliable and safe capacity increasing of the energy storage system can be achieved.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to an energy storage capacity expansion device and an energy storage system. Background Art

[0002] An energy storage system usually has multiple battery clusters connected in parallel, such as a DC measurement, to provide power. However, after the energy storage system has been running for a period of time, the power of each battery cluster will decay. If the power of the energy storage system is to be maintained, the capacity needs to be increased. However, the inventors have found that if a new battery cluster is directly connected for capacity increase, the remaining power of the new and old battery clusters will be inconsistent, and therefore their battery characteristics, resistance, etc. will be different, which will lead to inconsistent charging and discharging rates of the new and old battery clusters, resulting in individual batteries being fully charged or discharged first, which will limit the performance of the entire battery stack and affect the operating capacity of the energy storage system. Utility Model Content

[0003] In view of this, an embodiment of the present application provides an energy storage capacity expansion device and an energy storage system, which can achieve safe and reliable capacity expansion of the energy storage system.

[0004] In a first aspect, an embodiment of the present application provides an energy storage capacity expansion device, comprising:

[0005] A new battery cluster, a first step-up and step-down circuit, a second step-up and step-down circuit, and a high-voltage box;

[0006] The new battery cluster and the old battery cluster are connected in parallel to the DC bus;

[0007] Wherein, the new battery cluster is connected to the DC bus through the high-voltage box, the first step-up and step-down circuit and the second step-up and step-down circuit in sequence;

[0008] The first boost-buck circuit and the second boost-buck circuit are connected in reverse order so that a voltage between the first boost-buck circuit and the second boost-buck circuit forms a voltage difference with the voltage at the high voltage box end and with the voltage at the DC bus end.

[0009] In some embodiments, when the current of the new battery cluster flows to the DC bus, the first buck module in the first boost-buck circuit is used to buck the voltage of the high-voltage box; the second boost module in the second boost-buck circuit is used to boost the voltage bucked by the first buck module and output it to the DC bus;

[0010] When the new battery cluster is low on power, current flows from the DC bus to the new battery cluster, and the second buck module in the second boost-buck circuit is used to buck the voltage at the DC bus end; the first boost module in the first boost-buck circuit is used to boost the voltage bucked by the second buck module and output it to the new battery cluster.

[0011] In some embodiments, the device further comprises a control device; the old battery cluster and the new battery cluster are both communicatively connected to the control device;

[0012] The control device is connected to the first step-up and step-down circuit and the second step-up and step-down circuit respectively.

[0013] In some embodiments, the first boost-buck circuit and the second boost-buck circuit are both bidirectional DCDC converters.

[0014] In some embodiments, the first step-up and step-down circuit includes a first capacitor, a first diode, a second diode, a first switch tube, a second switch tube, a first inductor and a second capacitor;

[0015] The two ends of the second capacitor are respectively connected to the positive electrode and the negative electrode of the high-voltage box;

[0016] The first diode is connected in parallel with the second switch tube; the second diode is connected in parallel with the first switch tube; the positive electrode of the high-voltage box is connected to the junction of the negative electrode of the first diode and the second switch tube; the negative electrode of the high-voltage box is connected to the junction of the positive electrode of the second diode and the first switch tube;

[0017] One end of the first inductor is connected to the connection line between the first switch tube and the second switch tube; the other end of the first inductor is connected to the positive electrode connected to the first boost-buck circuit and the second boost-buck circuit;

[0018] The first capacitor is connected to the positive and negative terminals of the first boost-buck circuit and the second boost-buck circuit.

[0019] In some embodiments, the second boost and buck circuit includes a third capacitor, a third diode, a fourth diode, a third switch tube, a fourth switch tube, a second inductor, and a fourth capacitor;

[0020] Two ends of the fourth capacitor are respectively connected to the positive electrode and the negative electrode of the DC bus terminal;

[0021] The third diode is connected in parallel with the fourth switch tube; the fourth diode is connected in parallel with the third switch tube; the positive electrode of the DC bus terminal is connected to the junction of the negative electrode of the third diode and the fourth switch tube; the negative electrode of the DC bus terminal is connected to the junction of the positive electrode of the fourth diode and the third switch tube;

[0022] One end of the second inductor is connected to the connection line between the third switch tube and the fourth switch tube; the other end of the second inductor is connected to the positive electrode of the second boost-buck circuit connected to the first boost-buck circuit;

[0023] The third capacitor is connected to the positive and negative terminals of the second boost-buck circuit and the first boost-buck circuit.

[0024] In some embodiments, when the current of the new battery cluster flows to the DC bus, the control device is used to control the first switch tube and the fourth switch tube to be disconnected all the time, so that the current output by the high-voltage box flows to the DC bus through the first buck module and the second boost module in sequence.

[0025] In some embodiments, when the new battery cluster is low on power and current flows from the DC bus to the new battery cluster, the control device is used to control the third switch tube and the second switch tube to be disconnected all the time so that the current in the DC bus flows to the high-voltage box through the second step-down module and the first step-up module in sequence.

[0026] In some embodiments, the first buck module and the second buck module are Buck circuits.

[0027] In some embodiments, the first boost module and the second boost module are Boost circuits.

[0028] In a second aspect, an embodiment of the present application provides an energy storage system, comprising: a plurality of old battery clusters and the above-mentioned energy storage capacity expansion device.

[0029] The embodiments of the present application have the following beneficial effects:

[0030] The present application connects the new battery cluster and the old battery cluster in parallel to the DC bus, and connects the first boost-buck circuit and the second boost-buck circuit between the new battery cluster and the DC bus, and the first boost-buck circuit and the second boost-buck circuit are connected in reverse, so that no matter whether the current flows from the new battery cluster to the DC bus or from the DC bus to the new battery cluster, the control device can control the switch of the switch tube to form a voltage difference between the voltage of the first boost-buck circuit and the second boost-buck circuit and the high-voltage box of the new battery cluster, and also form a voltage difference with the DC bus end, so as to achieve precise adjustment of power and thus achieve precise and reliable power replenishment of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic diagram of the structure of the energy storage capacity expansion device according to an embodiment of the present application is shown;

[0033] Figure 2 A circuit diagram of an energy storage capacity expansion device according to an embodiment of the present application is shown;

[0034] Figure 3 A circuit diagram of a first step-down module according to an embodiment of the present application is shown;

[0035] Figure 4 A circuit diagram of a second boost module according to an embodiment of the present application is shown;

[0036] Figure 5 A circuit diagram of a second step-down module according to an embodiment of the present application is shown;

[0037] Figure 6 A schematic diagram of a first boost module circuit according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0039] The components of the embodiments of the present application generally described and shown in the drawings herein may be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0040] Hereinafter, the terms "including", "having" and their cognates that can be used in various embodiments of the present application are intended only to indicate specific features, numbers, steps, operations, elements, components or a combination of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or a combination of the foregoing items or increasing the possibility of one or more features, numbers, steps, operations, elements, components or a combination of the foregoing items. In addition, the terms "first", "second", "third" and the like are only used to distinguish descriptions and cannot be understood as indicating or implying relative importance.

[0041] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meanings as those generally understood by those skilled in the art to which the various embodiments of the present application belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meanings as the contextual meanings in the relevant technical field and will not be interpreted as having idealized meanings or overly formal meanings unless clearly defined in the various embodiments of the present application.

[0042] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0043] Based on the problems in the prior art, the present application proposes an energy storage capacity expansion device and an energy storage system that can keep the remaining power of a new battery cluster and an old battery cluster consistent.

[0044] Figure 1 A structural schematic diagram of an energy storage capacity expansion device of an embodiment of the present application is shown. Exemplarily, the energy storage capacity expansion device includes: a new battery cluster 20, a first boost-buck circuit 40, a second boost-buck circuit 50 and a high-voltage box 30. The new battery cluster 20 is connected to a DC bus 60 in parallel with the old battery cluster 10; wherein the old battery cluster 10 is a battery cluster originally existing in the energy storage system. The new battery cluster 20 is connected to the DC bus 60 through the high-voltage box 30, the first boost-buck circuit 40 and the second boost-buck circuit 50 in sequence. wherein the new battery cluster is a newly added battery cluster in the energy storage system.

[0045] When the current of the new battery cluster 20 flows to the DC bus 60, that is, when the electric energy of the new battery cluster 20 supplies power to the load, the first buck module of the first boost-buck circuit 40 is used to buck the voltage of the high-voltage box; the second boost module in the second boost-buck circuit 50 is used to boost the voltage after the voltage is bucked by the first buck module and output it to the DC bus 60; that is, the voltage of the high-voltage box 30 is first bucked by the first buck module in the first boost-buck circuit 40, and then boosted by the second boost module of the second boost-buck circuit 50 and output to the DC bus 60. 0; when the new battery cluster 20 is low on power, current flows from the DC bus 60 to the new battery cluster 20; the second buck module in the second boost-buck circuit 50 is used to buck the voltage at the DC bus end; the first boost module in the first boost-buck circuit 40 boosts the voltage after being bucked by the second buck module and outputs it to the new battery cluster 20; that is, the DC bus 60 is first bucked by the second buck module of the second boost-buck circuit 50, and then boosted by the first boost module of the first boost-buck circuit 40 and output to the new battery cluster 20. In this way, no matter from the new battery cluster 20 to the DC bus 60 or from the DC bus 60 to the new battery cluster 20, the voltage between the first boost-buck circuit 40 and the second boost-buck circuit 50 will be lower than the voltage at the high-voltage box 30 and the DC bus 60 end. In this way, a voltage difference is formed between the voltage between the first boost-buck circuit 40 and the second boost-buck circuit 50 and the voltage output by the high-voltage box 30, and a voltage difference is also formed between the voltage between the first boost-buck circuit 40 and the second boost-buck circuit 50 and the voltage of the DC bus 60. In this way, precise control can be achieved during power adjustment.

[0046] Furthermore, the energy storage capacity expansion device also includes a control device; the old battery cluster 10 and the new battery cluster 20 are both communicatively connected to the control device; and the control device is connected to the first boost-buck circuit 40 and the second boost-buck circuit 50 .

[0047] The control device can collect the operation information of each old battery cluster 10, wherein the operation information includes but is not limited to SOC (State of Charge, battery state of charge, also known as remaining power), current charge and discharge current, charge and discharge power and other information. The control device can calculate the current total charge and discharge power of the energy storage system through the collected operation information of each old battery cluster 10, and then set the charge and discharge power of the new battery cluster 20 according to the total charge and discharge power, wherein the charge and discharge power of the new battery cluster 20 = total charge and discharge power / (n+1), wherein n is the number of old battery clusters 10; then, according to the average SOC of the old battery cluster 10 and the SOC value of the new battery cluster 20, adjust the charge and discharge power of the new battery cluster 20, and then make the SOC of the new battery cluster 20 close to the SOC of the old battery cluster 10, and the charge and discharge power adjustment of the new battery cluster 20 is achieved by controlling the switching time of each switch tube by the control device.

[0048] Furthermore, the first step-up / step-down circuit 40 and the second step-up / step-down circuit are both bidirectional DCDC converters. In the present application, two DCDC circuits are reversely connected to achieve that no matter whether the current flows from the new battery cluster 20 to the DC bus 60 or from the DC bus 60 to the new battery cluster 20, a voltage difference can be formed between the voltage of the two DCDC converters and the high-voltage box 30, and a voltage difference can also be formed between the voltage of the two DCDC converters and the DC bus 60 segment, thereby achieving accurate power adjustment in both directions.

[0049] Specifically, Figure 2As shown, the first boost-buck circuit 40 includes a first capacitor C1, a first diode D1, a second diode D2, a first switch tube S1, a second switch tube S2, a first inductor L1, and a second capacitor C2; the second capacitor C2 is connected to the positive and negative ends of the high-voltage box 30; the first diode D1 is connected in parallel with the second switch tube S2; the second diode D2 is connected in parallel with the first switch tube S1; the positive electrode of the high-voltage box 30 is connected to the junction of the negative electrode of the first diode D1 and the second switch tube S2; the negative electrode of the high-voltage box 30 is connected to the junction of the positive electrode of the second diode D2 and the first switch tube S1; one end of the first inductor L1 is connected to the connecting line between the first switch tube S1 and the second switch tube S2; the other end of the first inductor L1 is connected to the positive electrode of the first boost-buck circuit 40 connected to the second boost-buck circuit 50; the first capacitor C1 is connected to the positive and negative ends of the first boost-buck circuit 40 connected to the second boost-buck circuit 50. The second boost-buck circuit 50 includes a third capacitor C3, a third diode D3, a fourth diode D4, a third switch tube S3, a fourth switch tube S4, a second inductor L2, and a fourth capacitor C3; the fourth capacitor C3 is connected to the positive and negative ends of the DC bus 60; the third diode D3 is connected in parallel with the fourth switch tube S4; the fourth diode D4 is connected in parallel with the third switch tube S3; the positive electrode of the DC bus 60 is connected to the junction of the negative electrode of the third diode D3 and the fourth switch tube S4; the negative electrode of the DC bus 60 is connected to the junction of the positive electrode of the fourth diode D4 and the third switch tube S3; one end of the second inductor L2 is connected to the connecting line between the third switch tube S3 and the fourth switch tube S4; the other end of the second inductor L2 is connected to the positive electrode of the second boost-buck circuit 50 connected to the first boost-buck circuit 40; the third capacitor C3 is connected to the positive and negative ends of the second boost-buck circuit 50 connected to the first boost-buck circuit 40.

[0050] Furthermore, when the current of the new battery cluster 20 flows to the DC bus 60, the control device is used to control the first switch tube S1 and the fourth switch tube S4 to be disconnected all the time, so that the high-voltage box 30 is connected to the DC bus 60 through the first buck module and the second boost module in sequence.

[0051] Specifically, when the first switch tube S1 is turned off, the first step-up and step-down circuit 40 is equivalent to Figure 3 The circuit shown, that is, the first step-down module is Figure 3In the circuit shown in FIG. 1 , when the first switch tube S1 is turned off, the first diode D1 is also turned off, so that the first step-down module is equivalent to a Buck circuit, thereby stepping down the voltage at the output end of the high-voltage box 30. When the fourth switch tube S4 is turned off, the second step-up and step-down circuit 50 is equivalent to Figure 4 The circuit shown, i.e. the second boost circuit is Figure 4 In the circuit shown, when the fourth switch tube S4 is turned off, the fourth diode D4 is also turned off, so that the second boost circuit is equivalent to a Boost circuit, thereby boosting the voltage between the first boost-buck circuit 40 and the second boost-buck circuit 50 .

[0052] When the new battery cluster 20 is low on power, when current flows from the DC bus 60 to the new battery cluster 20, the control device is used to control the third switch tube S3 and the second switch tube S2 to be disconnected all the time, so that the current is connected from the DC bus 60 to the high-voltage box 30 through the second buck module and the first boost module in sequence.

[0053] Specifically, when the third switch tube S3 is turned off, the second step-up and step-down circuit 50 is equivalent to Figure 5 The circuit shown, that is, the second step-down module is Figure 5 In the circuit shown in FIG. 1 , when the third switch tube S3 is turned off, the third diode D3 is also turned off, so that the second step-down module is equivalent to a Buck circuit (the current flows from the DC bus 60 end to the battery cluster end), thereby stepping down the voltage at the DC bus 60 end. When the second switch tube S2 is turned off, the first step-up and step-down circuit 40 is equivalent to Figure 6 The circuit shown, i.e. the first boost circuit is Figure 6 In the circuit shown, when the second switch tube S2 is turned off, the second diode D2 is also turned off, so that the first boost circuit is equivalent to a Boost circuit, thereby boosting the voltage between the first boost-buck circuit 40 and the second boost-buck circuit 50.

[0054] The present application connects the new battery cluster 20 and the old battery cluster 10 in parallel to the DC bus 60, and connects the first boost-buck circuit 40 and the second boost-buck circuit 50 between the new battery cluster 20 and the DC bus 60, and the first boost-buck circuit 40 and the second boost-buck circuit 50 are reversely connected, so that no matter whether the current flows from the new battery cluster 20 to the DC bus 60 or from the DC bus 60 to the new battery cluster 20, the control device can control the switch of the switch tube to form a voltage difference between the voltage of the first boost-buck circuit 40 and the second boost-buck circuit 50 and the high-voltage box 30 on the new battery cluster 20 side, and also form a voltage difference with the DC bus 60 end, so as to achieve precise adjustment of power, and thus achieve precise and reliable power replenishment of the energy storage system.

[0055] On the other hand, the present application also provides an energy storage system, comprising: a plurality of old battery clusters and the energy storage capacity expansion device as described above.

[0056] It can be understood that the options in the above embodiment are also applicable to this embodiment, so they will not be described again here.

[0057] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. An energy storage capacity expansion device, characterized in that: include: A new battery cluster, a first step-up and step-down circuit, a second step-up and step-down circuit, and a high-voltage box; The new battery cluster and the old battery cluster are connected in parallel to the DC bus; Wherein, the new battery cluster is connected to the DC bus through the high-voltage box, the first step-up and step-down circuit and the second step-up and step-down circuit in sequence; The first boost-buck circuit and the second boost-buck circuit are connected in reverse order so that a voltage between the first boost-buck circuit and the second boost-buck circuit forms a voltage difference with the voltage at the high voltage box end and with the voltage at the DC bus end.

2. The energy storage capacity expansion device according to claim 1, characterized in that: When the current of the new battery cluster flows to the DC bus, the first buck module in the first boost-buck circuit is used to buck the voltage of the high-voltage box; the second boost module in the second boost-buck circuit is used to boost the voltage bucked by the first buck module and output it to the DC bus; When the new battery cluster is low on power, current flows from the DC bus to the new battery cluster, and the second buck module in the second boost-buck circuit is used to buck the voltage at the DC bus end; the first boost module in the first boost-buck circuit is used to boost the voltage bucked by the second buck module and output it to the new battery cluster.

3. The energy storage capacity expansion device according to claim 2, characterized in that: The device further comprises a control device; the old battery cluster and the new battery cluster are both connected to the control device for communication; The control device is connected to the first step-up and step-down circuit and the second step-up and step-down circuit respectively.

4. The energy storage capacity expansion device according to claim 1, characterized in that: The first boost-buck circuit and the second boost-buck circuit are both bidirectional DCDC converters.

5. The energy storage capacity expansion device according to claim 3, characterized in that: The first step-up and step-down circuit includes a first capacitor, a first diode, a second diode, a first switch tube, a second switch tube, a first inductor and a second capacitor; The two ends of the second capacitor are respectively connected to the positive electrode and the negative electrode of the high-voltage box; The first diode is connected in parallel with the second switch tube; the second diode is connected in parallel with the first switch tube; the positive electrode of the high-voltage box is connected to the junction of the negative electrode of the first diode and the second switch tube; the negative electrode of the high-voltage box is connected to the junction of the positive electrode of the second diode and the first switch tube; One end of the first inductor is connected to the connection line between the first switch tube and the second switch tube; the other end of the first inductor is connected to the positive electrode connected to the first boost-buck circuit and the second boost-buck circuit; The first capacitor is connected to the positive and negative terminals of the first boost-buck circuit and the second boost-buck circuit.

6. The energy storage capacity expansion device according to claim 5, characterized in that: The second step-up and step-down circuit includes a third capacitor, a third diode, a fourth diode, a third switch tube, a fourth switch tube, a second inductor, and a fourth capacitor; Two ends of the fourth capacitor are respectively connected to the positive electrode and the negative electrode of the DC bus terminal; The third diode is connected in parallel with the fourth switch tube; the fourth diode is connected in parallel with the third switch tube; the positive electrode of the DC bus terminal is connected to the junction of the negative electrode of the third diode and the fourth switch tube; the negative electrode of the DC bus terminal is connected to the junction of the positive electrode of the fourth diode and the third switch tube; One end of the second inductor is connected to the connection line between the third switch tube and the fourth switch tube; the other end of the second inductor is connected to the positive electrode of the second boost-buck circuit connected to the first boost-buck circuit; The third capacitor is connected to the positive and negative terminals of the second boost-buck circuit and the first boost-buck circuit.

7. The energy storage capacity expansion device according to claim 6, characterized in that: When the current of the new battery cluster flows to the DC bus, the control device is used to control the first switch tube and the fourth switch tube to be disconnected all the time, so that the current output by the high-voltage box flows to the DC bus through the first buck module and the second boost module in sequence.

8. The energy storage capacity expansion device according to claim 6, characterized in that: When the new battery cluster is low on power and current flows from the DC bus to the new battery cluster, the control device is used to control the third switch tube and the second switch tube to be disconnected all the time, so that the current in the DC bus flows to the high-voltage box through the second buck module and the first boost module in sequence.

9. The energy storage capacity expansion device according to claim 2, characterized in that: The first step-down module and the second step-down module are Buck circuits.

10. The energy storage capacity expansion device according to claim 2, characterized in that: The first boost module and the second boost module are Boost circuits.

11. An energy storage system, characterized in that: include: A plurality of old battery clusters and an energy storage capacity expansion device as described in any one of claims 1-10.

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