Energy storage circuit and cascade energy storage system

Abstract

The invention relates to an energy storage circuit and a cascade energy storage system. The energy storage circuit (100) comprises an H-bridge circuit (1), wherein the input end of the H-bridge circuit is used for being connected with an external alternating current power supply; the input end of the LC filter circuit (2) is connected with the output end of the H-bridge circuit, the output end of the LC filter circuit is connected with the input end of an APF filter circuit (3), and the LC filter circuit is used for filtering high-frequency ripple current in the energy storage circuit; the output end of the APF filter circuit is used for being connected with a power battery, and the APF filter circuit is used for filtering the low-frequency ripple current in the energy storage circuit. Therefore, compared with the prior art that the ripple current is filtered independently through the LC filter circuit, the APF filter circuit is additionally arranged, and the APF filter circuit and the LC filter circuit jointly filter the ripple current, so that the value of the LC filter circuit is reduced, the size and the weight of electronic devices in the LC filter circuit are reduced, and the cost is reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of smart grid technology, and in particular, to an energy storage circuit and a cascade energy storage system. Background Art

[0002] Energy storage technology is a strategic technology to support the popularization of renewable energy, and is also a key technology to improve the flexibility and reliability of power systems. Cascade energy storage systems have the advantages of large single-unit capacity and low system unit watt-hour cost, and have broad application prospects. There is ripple current in the energy storage circuit of the cascade energy storage system. The ripple current increases the heat of the energy storage battery, reduces the battery life, reduces the system energy storage efficiency, and reduces the reliability of the cascade energy storage system.

[0003] In the related art, an LC filter circuit is usually provided to filter the ripple current. The electronic components in the LC filter circuit are large in size and weight, and the cost is high. Summary of the invention

[0004] The purpose of the present disclosure is to provide an energy storage circuit and a cascade energy storage system, which can reduce the volume and weight of electronic devices in the LC filter circuit in the energy storage circuit and reduce the cost.

[0005] In order to achieve the above object, the present disclosure provides an energy storage circuit, the energy storage circuit comprising:

[0006] An H-bridge circuit, wherein an input end of the H-bridge circuit is used to be connected to an external AC power source;

[0007] An LC filter circuit, wherein the input end of the LC filter circuit is connected to the output end of the H-bridge circuit, the output end of the LC filter circuit is connected to the input end of the APF filter circuit, and the LC filter circuit is used to filter the high-frequency ripple current in the energy storage circuit;

[0008] The APF filter circuit, the output end of the APF filter circuit is used to connect to the power battery, and the APF filter circuit is used to filter the low-frequency ripple current in the energy storage circuit.

[0009] Optionally, the H-bridge circuit includes a first phase bridge arm and a second phase bridge arm;

[0010] The first busbar ends of the first phase bridge arm and the second phase bridge arm are the positive output ends of the H-bridge circuit, and the second busbar ends of the first phase bridge arm and the second phase bridge arm are the negative output ends of the H-bridge circuit;

[0011] The midpoint of the first phase bridge arm is the first input end of the H-bridge circuit, and the midpoint of the second phase bridge arm is the second input end of the H-bridge circuit.

[0012] Optionally, the LC filter circuit includes a first inductor and a first capacitor;

[0013] One end of the first inductor is connected to one end of the first capacitor;

[0014] Among them, one end of the first inductor is the positive input end of the LC filter circuit, the other end of the first capacitor is the negative input end of the LC filter circuit, the other end of the first inductor is the positive output end of the LC filter circuit, and the other end of the first capacitor is the negative output end of the LC filter circuit.

[0015] Optionally, the APF filtering circuit includes a second inductor, a second capacitor and a third phase bridge arm;

[0016] The third phase bridge arm and the second capacitor are connected in parallel, and one end of the second inductor is connected to the midpoint of the third phase bridge arm;

[0017] Among them, the other end of the second inductor is the positive input terminal and the positive output terminal of the APF filter circuit, and the node between the lower bridge arm of the third phase bridge arm and the second capacitor is the negative input terminal and the negative output terminal of the APF filter circuit.

[0018] Optionally, the energy storage circuit further includes a main positive relay, a pre-charge relay and a pre-charge resistor;

[0019] The positive output terminal of the APF filter circuit is connected to the positive electrode of the power battery through the main positive relay, and is connected to the positive electrode of the power battery through the pre-charging relay and the pre-charging resistor in sequence.

[0020] Optionally, the energy storage circuit further includes a voltage stabilizing circuit, which is connected between the first input end of the H-bridge circuit and the second input end of the H-bridge circuit and is used to stabilize the voltage input to the H-bridge circuit.

[0021] Optionally, the voltage stabilizing circuit includes a first thyristor and a second thyristor, and the first thyristor and the second thyristor are connected in reverse parallel.

[0022] The present disclosure also provides a cascade energy storage system, comprising the above energy storage circuit.

[0023] Optionally, the cascade energy storage system includes three-phase branches, and each phase branch of the cascade energy storage system includes a plurality of the above-mentioned energy storage circuits connected in series.

[0024] Optionally, each phase branch of the cascade energy storage system further includes a third inductor, and the multiple energy storage circuits are connected to an external AC power source via the third inductor.

[0025] Through the above technical solution, the energy storage circuit includes: an H-bridge circuit, an LC filter circuit and an APF filter circuit. The input end of the H-bridge circuit is used to connect to an external AC power supply, the input end of the LC filter circuit is connected to the output end of the H-bridge circuit, the output end of the LC filter circuit is connected to the input end of the APF filter circuit, the LC filter circuit is used to filter the high-frequency ripple current in the energy storage circuit, the output end of the APF filter circuit is used to connect to the power battery, and the APF filter circuit is used to filter the low-frequency ripple current in the energy storage circuit. In this way, compared with the related art of filtering the ripple current by the LC filter circuit alone, by adding the APF filter circuit, the APF filter circuit and the LC filter circuit are used to filter the ripple current together, the value of the LC filter circuit is reduced, the volume and weight of the electronic devices in the LC filter circuit are reduced, and the cost is reduced.

[0026] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0028] Figure 1 is a schematic diagram of an energy storage circuit according to an exemplary embodiment.

[0029] Figure 2 is a schematic diagram of an energy storage circuit according to yet another exemplary embodiment.

[0030] Figure 3 is a schematic diagram of a cascade energy storage system according to an exemplary embodiment.

[0031] Description of Reference Numerals

[0032] 1 H-bridge circuit 2 LC filter circuit 3 APF filter circuit

[0033] 4 First inductor 5 First capacitor 6 Second inductor

[0034] 7 Second capacitor 8 Main positive relay 9 Pre-charge relay

[0035] 10 Pre-charge resistor 11 Voltage regulator circuit 12 First thyristor

[0036] 13 second thyristor 14 third inductor 100 energy storage circuit DETAILED DESCRIPTION

[0037] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0038] It should be noted that all actions of acquiring signals, information or data in the present disclosure are carried out in compliance with the relevant data protection laws and policies of the country where the device is located and with the authorization given by the owner of the corresponding device.

[0039] Figure 1 FIG. 1 is a schematic diagram of an energy storage circuit according to an exemplary embodiment. Figure 1 As shown, the energy storage circuit 100 includes an H-bridge circuit 1 , an LC filter circuit 2 and an APF filter circuit 3 .

[0040] The input end of the H-bridge circuit 1 is used to connect to an external AC power source;

[0041] The input end of the LC filter circuit 2 is connected to the output end of the H-bridge circuit 1, and the output end of the LC filter circuit 2 is connected to the input end of the APF filter circuit 3. The LC filter circuit 2 is used to filter the high-frequency ripple current in the energy storage circuit 100;

[0042] The output end of the APF filter circuit 3 is used to connect to the power battery, and the APF filter circuit 3 is used to filter the low-frequency ripple current in the energy storage circuit 100 .

[0043] Ripple current is the periodic fluctuation in the AC current in circuit components such as capacitors, inductors, and transformers.

[0044] The national standard stipulates that the ripple current in the energy storage circuit must be less than 5%. In the related art, since the ripple current in the energy storage circuit is filtered by the LC filter circuit alone, the electronic components in the LC filter circuit used are large in size and weight, and the cost is high (for example, the inductor uses 2.67mH and the capacitor uses 20mF).

[0045] In this solution, an APF filter circuit 3 is added to the energy storage circuit 100, and the low-frequency ripple current in the energy storage circuit 100 is filtered by the APF filter circuit 3, and the remaining high-frequency ripple current is filtered by the LC filter circuit 2. In this way, the value of the LC filter circuit 2 is reduced, and the volume and weight of the corresponding internal electronic components are reduced, and the cost is reduced (for example, after adding the APF filter circuit 3, the inductor in the LC filter circuit 2 is 0.5mH and the capacitor is 20mF). Moreover, adding the APF filter circuit 3 can also further reduce the ripple current in the energy storage circuit 100 (for example, when the LC filter circuit 2 is set alone, the ripple current in the energy storage circuit 100 is 4.97%; after adding the APF filter circuit 3, the ripple current in the energy storage circuit 100 is reduced to 2.6%).

[0046] Through the above technical solution, the energy storage circuit includes: an H-bridge circuit, an LC filter circuit and an APF filter circuit. The input end of the H-bridge circuit is used to connect to an external AC power supply, the input end of the LC filter circuit is connected to the output end of the H-bridge circuit, the output end of the LC filter circuit is connected to the input end of the APF filter circuit, the LC filter circuit is used to filter the high-frequency ripple current in the energy storage circuit, the output end of the APF filter circuit is used to connect to the power battery, and the APF filter circuit is used to filter the low-frequency ripple current in the energy storage circuit. In this way, compared with the related art in which the ripple current is only filtered by the LC filter circuit, by adding the APF filter circuit, the APF filter circuit and the LC filter circuit are used to filter the ripple current together, the value of the LC filter circuit is reduced, the volume and weight of the electronic devices in the LC filter circuit are reduced, and the cost is reduced.

[0047] Figure 2 FIG. 1 is a schematic diagram of an energy storage circuit according to another exemplary embodiment. Figure 2 As shown, the H-bridge circuit 1 includes a first phase bridge arm and a second phase bridge arm.

[0048] The first busbar ends of the first phase bridge arm and the second phase bridge arm are the positive output ends of the H-bridge circuit 1, and the second busbar ends of the first phase bridge arm and the second phase bridge arm are the negative output ends of the H-bridge circuit 1;

[0049] The midpoint of the first phase bridge arm is the first input terminal of the H-bridge circuit 1 , and the midpoint of the second phase bridge arm is the second input terminal of the H-bridge circuit 1 .

[0050] The first phase bridge arm in the H-bridge circuit 1 may be any one of the two phase bridge arms of the H-bridge circuit 1. The input end of the H-bridge circuit 1 includes a first input end and a second input end.

[0051] In this embodiment, a first phase bridge arm and a second phase bridge arm are provided in the H-bridge circuit 1, which has a simple structure and high reliability.

[0052] In yet another embodiment, the LC filter circuit 2 includes a first inductor 4 and a first capacitor 5 .

[0053] One end of the first inductor 4 is connected to one end of the first capacitor 5;

[0054] Among them, one end of the first inductor 4 is the positive input end of the LC filter circuit 2, the other end of the first capacitor 5 is the negative input end of the LC filter circuit 2, the other end of the first inductor 4 is the positive output end of the LC filter circuit 2, and the other end of the first capacitor 5 is the negative output end of the LC filter circuit 2.

[0055] The current output by the H-bridge circuit 1 is input into the LC filter circuit 2 via the other end of the first inductor 4 and the other end of the first capacitor 5. The first inductor 4 has the characteristics of passing direct current, blocking alternating current, passing low frequency and blocking high frequency, and the first capacitor 5 has the characteristics of passing alternating current and blocking direct current, thereby effectively filtering the high-frequency ripple current in the current output by the H-bridge.

[0056] In this embodiment, by providing the first inductor 4 and the first capacitor 5 in the LC filter circuit 2, the high-frequency ripple current in the energy storage circuit 100 can be filtered reliably and effectively.

[0057] In yet another embodiment, the APF filter circuit 3 includes a second inductor 6, a second capacitor 7 and a third phase bridge arm.

[0058] The third phase bridge arm is connected in parallel with the second capacitor 7, and one end of the second inductor 6 is connected to the midpoint of the third phase bridge arm;

[0059] Among them, the other end of the second inductor 6 is the positive input terminal and the positive output terminal of the APF filter circuit 3, and the node between the lower bridge arm of the third phase bridge arm and the second capacitor 7 is the negative input terminal and the negative output terminal of the APF filter circuit 3.

[0060] After the current output by the LC filter circuit 2 is input into the APF filter circuit 3, the third phase bridge arm and the second inductor 6 work together to generate a harmonic current on the second inductor 6 that is opposite to and equal to the low-frequency ripple current in the input APF filter circuit 3, thereby filtering the low-frequency ripple current in the current.

[0061] In this embodiment, by providing the second inductor 6, the second capacitor 7 and the third phase bridge arm in the APF filter circuit 3, the low-frequency ripple current in the energy storage circuit 100 can be reliably and effectively filtered.

[0062] In yet another embodiment, the energy storage circuit 100 further includes a main positive relay 8 , a pre-charge relay 9 and a pre-charge resistor 10 .

[0063] The positive output terminal of the APF filter circuit 3 is connected to the positive electrode of the power battery through the main positive relay 8, and is connected to the positive electrode of the power battery through the pre-charging relay 9 and the pre-charging resistor 10 in sequence.

[0064] In the pre-charging state, the pre-charging relay 9 is closed, the main positive relay 8 is disconnected, and the circuit formed by the power battery, the pre-charging resistor 10 and the pre-charging relay 9 is connected. After the pre-charging is completed, the pre-charging relay 9 is disconnected and the main positive relay 8 is closed.

[0065] In this embodiment, the power battery can be reliably charged by providing the main positive relay 8 , the pre-charging relay 9 and the pre-charging resistor 10 in the energy storage circuit 100 .

[0066] In another embodiment, the energy storage circuit 100 further includes a voltage stabilizing circuit 11. The voltage stabilizing circuit 11 is connected between the first input terminal of the H-bridge circuit 1 and the second input terminal of the H-bridge circuit 1, and is used to stabilize the voltage input to the H-bridge circuit 1.

[0067] In this embodiment, by providing the voltage stabilizing circuit 11 in the energy storage circuit 100 , the voltage input to the H-bridge circuit 1 can be stabilized reliably and effectively.

[0068] In yet another embodiment, the voltage stabilizing circuit 11 includes a first thyristor 12 and a second thyristor 13 , and the first thyristor 12 and the second thyristor 13 are connected in reverse parallel.

[0069] In this embodiment, the first thyristor 12 and the second thyristor 13 in the voltage stabilizing circuit 11 are connected in reverse parallel, which has a simple structure, high reliability and low cost.

[0070] The present disclosure also provides a cascade energy storage system, comprising the above-mentioned energy storage circuit 100.

[0071] In yet another embodiment, the cascade energy storage system includes three-phase branches, and each phase branch of the cascade energy storage system includes a plurality of the above-mentioned energy storage circuits 100 connected in series. Figure 3 is a schematic diagram of a cascade energy storage system according to an exemplary embodiment. Figure 3 In the embodiment of the present invention, each branch of the cascade energy storage system includes three series-connected energy storage circuits 100. The three-phase branches of the cascade energy storage system are connected in a star configuration.

[0072] In this embodiment, by providing a plurality of series-connected energy storage circuits 100 in each phase branch of the cascade energy storage system 100 , the capacity of the cascade energy storage system is higher and the unit watt-hour cost is lower.

[0073] In yet another embodiment, each phase branch of the cascade energy storage system further includes a third inductor 14 , and the plurality of energy storage circuits 100 are connected to an external AC power source via the third inductor 14 .

[0074] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0075] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0076] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A tank circuit, characterized in that: The energy storage circuit (100) comprises: An H-bridge circuit (1), wherein an input end of the H-bridge circuit (1) is used to be connected to an external AC power source; An LC filter circuit (2), wherein the input end of the LC filter circuit (2) is connected to the output end of the H-bridge circuit (1), the output end of the LC filter circuit (2) is connected to the input end of the APF filter circuit (3), and the LC filter circuit (2) is used to filter the high-frequency ripple current in the energy storage circuit (100); The APF filter circuit (3), the output end of the APF filter circuit (3) is used to be connected to the power battery, and the APF filter circuit (3) is used to filter the low-frequency ripple current in the energy storage circuit (100).

2. The energy storage circuit according to claim 1, characterized in that: The H-bridge circuit (1) comprises a first phase bridge arm and a second phase bridge arm; The first busbar ends of the first phase bridge arm and the second phase bridge arm are the positive output ends of the H-bridge circuit (1), and the second busbar ends of the first phase bridge arm and the second phase bridge arm are the negative output ends of the H-bridge circuit (1); The midpoint of the first phase bridge arm is the first input end of the H-bridge circuit (1), and the midpoint of the second phase bridge arm is the second input end of the H-bridge circuit (1).

3. The energy storage circuit according to claim 1, characterized in that: The LC filter circuit (2) comprises a first inductor (4) and a first capacitor (5); One end of the first inductor (4) is connected to one end of the first capacitor (5); One end of the first inductor (4) is the positive input end of the LC filter circuit (2), the other end of the first capacitor (5) is the negative input end of the LC filter circuit (2), the other end of the first inductor (4) is the positive output end of the LC filter circuit (2), and the other end of the first capacitor (5) is the negative output end of the LC filter circuit (2).

4. The energy storage circuit according to claim 1, characterized in that: The APF filter circuit (3) comprises a second inductor (6), a second capacitor (7) and a third phase bridge arm; The third phase bridge arm and the second capacitor (7) are connected in parallel, and one end of the second inductor (6) is connected to the midpoint of the third phase bridge arm; The other end of the second inductor (6) is the positive input terminal and the positive output terminal of the APF filter circuit (3), and the node between the lower bridge arm of the third phase bridge arm and the second capacitor (7) is the negative input terminal and the negative output terminal of the APF filter circuit (3).

5. The energy storage circuit according to claim 1, characterized in that: The energy storage circuit (100) further comprises a main positive relay (8), a pre-charging relay (9) and a pre-charging resistor (10); The positive output end of the APF filter circuit (3) is connected to the positive electrode of the power battery through the main positive relay (8), and is connected to the positive electrode of the power battery through the pre-charging relay (9) and the pre-charging resistor (10) in sequence.

6. The energy storage circuit according to claim 2, characterized in that: The energy storage circuit (100) further comprises a voltage stabilizing circuit (11), wherein the voltage stabilizing circuit (11) is connected between a first input end of the H-bridge circuit (1) and a second input end of the H-bridge circuit (1) and is used for stabilizing a voltage input to the H-bridge circuit (1).

7. The energy storage circuit according to claim 6, characterized in that: The voltage stabilizing circuit (11) comprises a first thyristor (12) and a second thyristor (13), wherein the first thyristor (12) and the second thyristor (13) are connected in reverse parallel.

8. A cascade energy storage system, characterized in that: The energy storage circuit (100) comprises any one of claims 1 to 7.

9. The cascade energy storage system according to claim 8, characterized in that: The cascade energy storage system comprises three-phase branches, and each phase branch of the cascade energy storage system comprises a plurality of energy storage circuits (100) according to any one of claims 1 to 7 connected in series.

10. The cascade energy storage system according to claim 9, characterized in that: Each phase branch of the cascade energy storage system further comprises a third inductor (14), and the plurality of energy storage circuits (100) are connected to an external AC power source via the third inductor (14).

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