Power conversion system-based charging method and apparatus, and power conversion system

Abstract

A power conversion system-based charging method and apparatus, and a power conversion system. A soft-start circuit (301) connected in parallel with a first branch (302) can be used to perform voltage compensation on a bus by means of a direct current side. A voltage of the first branch (302) of a positive electrode of a battery is acquired as a first voltage, a voltage of a second branch (303) of the positive electrode of the battery is acquired as a second voltage, a difference between said voltages is calculated, the value of the first voltage is compared with the value of the second voltage when the difference is greater than a preset voltage value, the bus undergoes voltage compensation by using the direct current side so that the voltage of the bus is equal to the smaller voltage value, and then the bus is charged on the basis of the larger voltage value. A power conversion system is compatible with a multi-branch system and is used for a multi-branch topology, and a voltage compensation method of the power conversion system is not limited by the incapability to perform voltage compensation due to a low voltage of the branch where the soft-start circuit (301), thereby reducing the cost and improving the efficiency without affecting the system function, and greatly improving the utilization rate.

Description

A method and device for charging based on energy storage converter and energy storage converter

[0001] The present invention claims priority to Chinese patent application number 202311096847.X filed with the State Intellectual Property Office of the People's Republic of China on August 28, 2023, entitled “A method, device and energy storage converter for charging based on energy storage converter”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to the field of energy storage, and in particular to a method and device for charging an energy storage converter, and an energy storage converter. Background Art

[0003] A power conversion system (PCS) is a device in an energy storage system that connects the battery system and the grid, enabling bidirectional power conversion. It converts the battery's DC power into AC power for transmission to the grid or AC loads, and also rectifies the grid's AC power into DC power to charge the battery.

[0004] During the charging and discharging process, common PCS systems can experience voltage imbalances between battery packs, leading to battery damage and an inability for the PCS to provide stable power. This in turn increases costs and reduces efficiency. Therefore, reducing costs, increasing efficiency, and improving PCS utilization without compromising system functionality have become pressing technical challenges for those skilled in the art.

[0005] Summary of the Invention

[0006] Based on the above problems, the present application provides a method, device and energy storage converter based on energy storage converter charging, so as to reduce costs and increase efficiency and improve the utilization rate of PCS without affecting the system function.

[0007] The present application discloses a method for charging an energy storage converter, the method comprising:

[0008] Acquire a first branch voltage of the positive electrode of the battery as a first voltage, and a second branch voltage of the positive electrode of the battery as a second voltage;

[0009] calculating a voltage difference between the first voltage and the second voltage;

[0010] When the voltage difference is greater than a preset voltage value, comparing the first voltage with the second voltage to select the larger voltage value and the smaller voltage value;

[0011] Using the battery on the DC side to replenish the bus voltage to a value equal to the smaller voltage value;

[0012] The busbar is charged according to the larger voltage value.

[0013] Optionally, the utilizing the battery on the DC side to supplement the bus voltage to be equal to the smaller voltage value includes:

[0014] Controlling the soft-start contactor provided on the first branch to close so as to supplement power to the busbar;

[0015] When the bus voltage is charged to a value equal to the smaller voltage value, the slow-start contactor is controlled to be disconnected.

[0016] Optionally, charging the bus according to the larger voltage value includes:

[0017] If the voltage value of the second voltage is the smaller voltage value, controlling the second DC contactor on the second branch to close;

[0018] When the second voltage is equal to the first voltage, closing the first DC contactor on the first branch;

[0019] The bus is charged with the voltage value of the first voltage being the larger voltage value.

[0020] Optionally, charging the bus according to the larger voltage value includes:

[0021] If the voltage value of the first voltage is the smaller voltage value, controlling the first DC contactor on the first branch to close;

[0022] When the first voltage and the second voltage are equal, closing the second DC contactor on the second branch;

[0023] The bus is charged with the second voltage having the larger voltage value.

[0024] Based on the above-mentioned method for charging based on an energy storage converter, the present application also discloses a device for charging based on an energy storage converter, comprising: a voltage acquisition unit, a difference calculation unit, a comparison unit, a power replenishment unit, and a charging unit;

[0025] The voltage acquisition unit is configured to acquire the voltage of the first branch of the positive electrode of the battery as a first voltage and the voltage of the second branch of the positive electrode of the battery as a second voltage;

[0026] The difference calculation unit is used to calculate the voltage difference between the first voltage and the second voltage;

[0027] The comparison unit is configured to compare the first voltage with the second voltage when the voltage difference is greater than a preset voltage value, and select the larger voltage value and the smaller voltage value;

[0028] The power replenishment unit is used to use the battery on the DC side to replenish the bus voltage to a value equal to the smaller voltage value;

[0029] The charging unit is used to charge the bus according to the larger voltage value.

[0030] Optionally, the power supply unit includes:

[0031] a soft-start contactor closing subunit, configured to control the closing of a soft-start contactor provided on the first branch to supplement power to the busbar;

[0032] The soft-start contactor disconnecting subunit is used to control the soft-start contactor to disconnect when the bus voltage is charged to be equal to the smaller voltage value.

[0033] Optionally, the charging unit is used to:

[0034] If the voltage value of the second voltage is the smaller voltage value, controlling the second DC contactor on the second branch to close;

[0035] When the second voltage is equal to the first voltage, closing the first DC contactor on the first branch;

[0036] The bus is charged with the voltage value of the first voltage being the larger voltage value.

[0037] Optionally, the charging unit is used to:

[0038] If the voltage value of the first voltage is the smaller voltage value, controlling the first DC contactor on the first branch to close;

[0039] When the first voltage and the second voltage are equal, closing the second DC contactor on the second branch;

[0040] The bus is charged with the second voltage having the larger voltage value.

[0041] Based on the above-mentioned method for charging based on an energy storage converter, the present application also discloses an energy storage converter, comprising: a soft start circuit, a first branch, a second branch and a measurement and control module;

[0042] The slow-start circuit is connected in parallel only with the first branch; there is only one slow-start circuit;

[0043] The battery side of the energy storage converter is connected to the positive electrode of the battery through the first branch and the second branch;

[0044] The soft start circuit is used to supplement the power of the busbar;

[0045] The measurement and control module is used to obtain the voltages of the first branch, the second branch and the bus, calculate the voltage difference between the first branch and the second branch, compare the voltages of the first branch and the second branch, and control the working states of the soft-start circuit, the first branch and the second branch based on the calculation results and the comparison results.

[0046] Optionally, the slow-start circuit includes a slow-start contactor;

[0047] The slow-start contactor is connected in parallel with the first DC contactor on the first branch.

[0048] Optionally, the second branch is provided with a second DC contactor.

[0049] Optionally, the bus side of the energy storage converter is connected to a bus voltage balancing circuit.

[0050] The present application discloses a method, device and energy storage converter based on energy storage converter charging. It is possible to use a soft start circuit connected in parallel with the first branch to supplement the busbar through the DC side. The voltage of the first branch of the positive electrode of the battery is obtained as the first voltage, and the voltage of the second branch of the positive electrode of the battery is obtained as the second voltage, and the difference is calculated. When the difference is greater than the preset voltage value, the first voltage and the second voltage are compared, and the busbar voltage is supplemented to the same value as the smaller voltage value using the DC side, and then the busbar is charged according to the larger voltage value. The energy storage converter described in the present application is compatible with multi-branch systems and can be used for multi-branch topologies, and its supplementary power method is not limited by the low voltage of the branch where the soft start circuit is located, which can reduce costs and increase efficiency without affecting the system function, and greatly improve the utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0052] FIG1 is a schematic flow chart of a method for charging an energy storage converter according to an embodiment of the present application;

[0053] FIG2 is a flow chart of another method for charging an energy storage converter according to an embodiment of the present application;

[0054] FIG3 a is a schematic structural diagram of an energy storage converter disclosed in an embodiment of the present application;

[0055] FIG3 b is a schematic structural diagram of an energy storage converter disclosed in an embodiment of the present application when actually in use;

[0056] FIG4 is a schematic structural diagram of a device for charging based on an energy storage converter disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0058] Example 1: Based on the energy storage converter disclosed above, this example correspondingly discloses a charging method based on the energy storage converter.

[0059] Specifically, referring to FIG1 , a method for charging an energy storage converter disclosed in this embodiment includes the following steps:

[0060] Step 101: obtaining a first branch voltage of a positive electrode of a battery as a first voltage and a second branch voltage of a positive electrode of the battery as a second voltage.

[0061] In the method described in this embodiment, as an optional method, the battery voltages of the first branch and the second branch from the DC side are obtained as the first voltage and the second voltage respectively based on voltage sampling. At the same time, the voltage of the bus voltage balancing circuit can also be sampled and obtained as the bus voltage.

[0062] Step 102: Calculate the voltage difference between the first voltage and the second voltage.

[0063] In the method described in this embodiment, as an optional method, the voltage difference is an absolute value. As another optional method, the first voltage can be divided by the second voltage to obtain a ratio of the first voltage to the second voltage, and then compared with a preset ratio in a subsequent step. The method for calculating the first voltage and the second voltage is not specifically limited here; it is sufficient to be able to determine that the difference between the first voltage and the second voltage is too large.

[0064] Step 103: When the voltage difference is greater than a preset voltage value, compare the first voltage and the second voltage to select the larger voltage value and the smaller voltage value.

[0065] In the method described in this embodiment, as an optional method, the preset voltage value can be set to 15V, and the numerical value of the preset voltage value is not specifically limited. When the voltage difference is less than or equal to the preset voltage value, there is no need to supplement the busbar.

[0066] In the method described in this embodiment, the smaller voltage value of the first voltage and the second voltage is selected to replenish the bus voltage to be equal to the smaller voltage value. The larger voltage value of the first voltage and the second voltage is selected to charge the bus voltage to be equal to the larger voltage value.

[0067] Step 104: Utilize the battery on the DC side to supplement the bus voltage to a value equal to the smaller voltage value.

[0068] In the method described in this embodiment, the recharging process may specifically include, for example, controlling the soft-start contactor on the first branch to close when the first voltage is greater than the second voltage. At this point, the battery on the DC side is soft-started and connected to the battery side, while the AC side grid is disconnected, thereby using the battery to recharge the busbar. When the busbar voltage reaches the same level as the second voltage, the soft-start contactor is controlled to open.

[0069] Step 105: charging the busbar according to the larger voltage value.

[0070] In the method described in this embodiment, as an optional method, if the second voltage value is a smaller voltage value, the second DC contactor on the second branch is controlled to close, enabling the DC grid-connected constant voltage mode. In this case, the DC grid-connected constant voltage mode can specifically be configured to set the target voltage value to a larger voltage value, that is, the voltage value of the first voltage. When the second voltage value is equal to the target voltage value, the first DC contactor on the first branch is controlled to close, and the busbar is charged at the target voltage value.

[0071] If the first voltage is a lower value, the first DC contactor on the first branch is controlled to close, enabling the DC grid-connected constant voltage mode. Specifically, the DC grid-connected constant voltage mode may include setting the target voltage to a higher value, namely, the second voltage. When the first voltage reaches the target voltage, the second DC contactor on the second branch is controlled to close, charging the bus at the target voltage.

[0072] In the method described in this embodiment, the equality of the voltage values ​​is relative. As an optional method, the absolute value of the difference between the two voltage values ​​to be equal can be set to be within a preset range. For example, if the preset range is set to ±2V, and the voltage value of the first voltage is 10V and the second branch needs to be charged, charging of the second branch can be determined to be complete when the voltage value of the second voltage reaches 8V-12V.

[0073] The method described in this embodiment can ignore the condition that the second voltage must be less than the first voltage in order to use the slow start to supplement the power (the power can only be supplemented if the battery voltage on the DC side of the branch to which the slow start circuit is connected in parallel is high). Instead, the slow start circuit is first enabled and connected to the battery on the DC side, so that the battery is used to supplement the power of the bus. Then the slow start circuit is disconnected, and the bus can be charged using the AC side grid. In this process, both the AC side grid and the DC side battery are connected to the grid, and the grid is used to charge the battery, and the voltage value of the low-voltage branch is charged to be consistent with the voltage value of the high-voltage branch, and then the bus is charged until the bus voltage is consistent with the voltage value of the high-voltage branch. The method of the present application has a good application in energy storage converter systems with power limitations, can improve the utilization rate of energy storage converters, and solve the problem of voltage imbalance in branches without slow start. It can also be used in multi-branch systems. The following will introduce the situation where there are multiple branches (more than two branches) topology in the system through the second embodiment.

[0074] Example 2: This application discloses another method for charging based on an energy storage converter. Please refer to Figure 2. The method described in this embodiment is applied to an energy storage converter described in this application, specifically for a multi-branch topology, specifically three branches.

[0075] Step 201: respectively sampling and obtaining the voltages of the three battery positive electrode branches BAT1+, BAT2+ and BAT3+, ie, U1, U2 and U3.

[0076] In the method described in this embodiment, a slow-start circuit is connected in parallel to BAT1+, and the slow-start circuit includes a slow-start contactor. BAT2+ and BAT3+ include DC contactors.

[0077] Step 202: Subtract two voltages of U1, U2 and U3 to obtain three voltage difference values.

[0078] In the method described in this embodiment, the voltage difference is an absolute value. As an alternative, U1, U2, and U3 can be divided separately to obtain three voltage ratios, which can be compared with a preset voltage ratio in subsequent steps. The calculation and comparison methods of the three voltage values ​​are not specifically limited here; they can be used to complete the subsequent steps.

[0079] Step 203: Determine whether any one of the three voltage differences is greater than a preset voltage value, if yes, proceed to step 204. If no, no operation is performed.

[0080] In the method described in this embodiment, when the voltage differences are all less than a preset voltage value, there is no need to supplement the busbar with electricity, wherein the preset voltage value can be set to 15V.

[0081] Step 204: Select the maximum voltage value, medium voltage value, and minimum voltage value according to the magnitudes of the voltage values of U1, U2, and U3.

[0082] Step 205: Energize the soft-start contactor on BAT1+, charge the bus until the difference between the bus voltage value and the minimum voltage value reaches the preset range, and then de-energize the soft-start contactor.

[0083] In the method described in this embodiment, the preset range can be set to ±2V.

[0084] Step 206: Energize the DC contactor of the branch where the minimum voltage value is located, charge the branch where the minimum voltage value is located until the difference between the minimum voltage value and the medium voltage value reaches the preset range, and then close the DC contactor of the branch where the medium voltage value is located.

[0085] Step 207: Charge the branch where the medium voltage value is located until the difference between the medium voltage value and the maximum voltage value reaches the preset range, and then close the DC contactor of the branch where the maximum voltage value is located.

[0086] The method described in this embodiment is applicable to the case of a three-branch topology. It is not restricted by BAT2 < BAT1 (the battery voltage of the soft-start path should be higher for charging). It adopts the method of first soft-starting to charge the bus, that is, using the branch with a higher battery voltage to charge the bus. When the bus voltage is charged to the same value as the minimum voltage value, DC grid connection is carried out at a constant voltage, charging the lowest battery voltage to the same as the high-voltage battery, and then charging the bus voltage to the same as the high-voltage battery. It is not limited to the dual-branch topology, has high versatility, can save the soft-start circuit, and reduce costs.

[0087] Based on the method of charging based on an energy storage converter disclosed in the above embodiment, this embodiment correspondingly discloses an energy storage converter. Specifically, referring to FIG. 3a, the energy storage converter includes: a soft-start circuit 301, a first branch 302, a second branch 303, and a measurement and control module 304;

[0088] In the energy storage converter described in this application, the soft-start circuit 301 is only connected in parallel with the first branch 302, and the number of soft-start circuits 301 is one. The battery side of the energy storage converter is connected to the positive pole of the battery on the DC side through the first branch 302 and the second branch 303. The soft-start circuit is used to charge the bus.

[0089] In the energy storage converter described in this application, the measurement and control module 304 is used to obtain the voltages of the first branch 302, the second branch 303, and the bus, calculate the voltage difference between the first branch 302 and the second branch 303, compare the voltage magnitudes of the first branch 302 and the second branch 303, and control the working states of the soft-start circuit 301, the first branch 302, and the second branch 303 according to the calculation results and comparison results.

[0090] Figure 3b is a schematic diagram of the structure of the energy storage converter described in this application during actual use. As shown in Figure 3b, BAT1+ is the first branch of the battery's positive electrode, BAT2+ is the second branch, and BAT- is the battery's negative electrode branch. The box shows the internal structure of the energy storage converter, where KM1 is the slow-start contactor in the slow-start circuit, KM2 is the first DC contactor in the first branch, KM3 is the second DC contactor in the second branch, and KM4 is the DC contactor in the battery's negative electrode branch. The left side of the box is the battery, and the right side is the busbar voltage balancing circuit.

[0091] In the energy storage converter described in this application, KM1 and KM2 are connected in parallel. When KM1 is closed, it can be used to supplement the busbar power. KM3 and KM2 are used to achieve DC grid-connected constant voltage. The busbar voltage balancing circuit is used to achieve DC grid-connected constant voltage.

[0092] Based on the energy storage converter charging method disclosed in the above embodiment, this embodiment correspondingly discloses an energy storage converter charging device. Referring to FIG4 , the energy storage converter charging device includes: a voltage acquisition unit 401, a difference calculation unit 402, a comparison unit 403, a power supply unit 404, and a charging unit 405;

[0093] The voltage acquisition unit 401 is configured to acquire a first branch voltage of the positive electrode of the battery as a first voltage and a second branch voltage of the positive electrode of the battery as a second voltage;

[0094] The difference calculation unit 402 is used to calculate the voltage difference between the first voltage and the second voltage;

[0095] The comparison unit 403 is configured to compare the first voltage with the second voltage when the voltage difference is greater than a preset voltage value, and select the larger voltage value and the smaller voltage value;

[0096] The power replenishment unit 404 is configured to utilize the battery on the DC side to replenish the bus voltage to a value equal to the smaller voltage value;

[0097] The charging unit 405 is configured to charge the bus according to the larger voltage value.

[0098] Optionally, the power supply unit 404 includes:

[0099] a soft-start contactor closing subunit, configured to control the closing of a soft-start contactor provided on the first branch to supplement power to the busbar;

[0100] The soft-start contactor disconnecting subunit is used to control the soft-start contactor to disconnect when the bus voltage is charged to be equal to the smaller voltage value.

[0101] Optionally, the charging unit 405 is configured to:

[0102] If the voltage value of the second voltage is the smaller voltage value, controlling the second DC contactor on the second branch to close;

[0103] When the second voltage is equal to the first voltage, closing the first DC contactor on the first branch;

[0104] The bus is charged with the voltage value of the first voltage being the larger voltage value.

[0105] Optionally, the charging unit 405 is configured to:

[0106] If the voltage value of the first voltage is the smaller voltage value, controlling the first DC contactor on the first branch to close;

[0107] When the first voltage and the second voltage are equal, closing the second DC contactor on the second branch;

[0108] The bus is charged with the second voltage having the larger voltage value.

[0109] The embodiments in this specification are described in a progressive manner. As for the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the methods.

[0110] It should also be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0111] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0112] The features described in the embodiments of this specification can be replaced with each other or combined to enable professional and technical personnel in this field to implement or use this application.

[0113] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A charging method based on an energy storage converter, characterized in that: include: The voltage of the first branch of the positive electrode of the battery is obtained as a first voltage, and the voltage of the second branch of the positive electrode of the battery is obtained as a second voltage; calculating a voltage difference between the first voltage and the second voltage; When the voltage difference is greater than a preset voltage value, comparing the voltage values ​​of the first voltage and the second voltage, and selecting a larger voltage value and a smaller voltage value; Using the battery on the DC side to supplement the bus voltage to a value equal to the smaller voltage value; The bus is charged according to the larger voltage value.

2. The method according to claim 1, characterized in that The method of using the battery on the DC side to supplement the bus voltage to be equal to the smaller voltage value includes: Controlling the slow-start contactor disposed on the first branch to close so as to supplement power to the busbar; When the bus voltage is charged to a value equal to the smaller voltage value, the slow-start contactor is controlled to be disconnected.

3. The method according to claim 1, characterized in that The step of charging the bus according to the larger voltage value comprises: If the voltage value of the second voltage is the smaller voltage value, controlling the second DC contactor on the second branch to close; When the second voltage is equal to the first voltage, closing the first DC contactor on the first branch; The bus is charged with a voltage value of the first voltage being the larger voltage value.

4. The method according to claim 1, characterized in that: The step of charging the bus according to the larger voltage value comprises: If the voltage value of the first voltage is the smaller voltage value, controlling the first DC contactor on the first branch to close; When the voltage values ​​of the first voltage and the second voltage are equal, closing the second DC contactor on the second branch; The bus is charged with a voltage value of the second voltage being the larger voltage value.

5. A device for charging based on an energy storage converter, characterized in that: include: Voltage acquisition unit, difference calculation unit, comparison unit, power replenishment unit and charging unit; The voltage acquisition unit is used to acquire the first branch voltage of the positive electrode of the battery as a first voltage, and the second branch voltage of the positive electrode of the battery as a second voltage; The difference calculation unit is used to calculate the voltage difference between the first voltage and the second voltage; The comparison unit is used to compare the voltage values ​​of the first voltage and the second voltage when the voltage difference is greater than a preset voltage value, and select a larger voltage value and a smaller voltage value; The power replenishment unit is used to use the battery on the DC side to replenish the bus voltage to a value equal to the smaller voltage value; The charging unit is used to charge the bus according to the larger voltage value.

6. The device according to claim 5, characterized in that The power replenishment unit comprises: The slow-start contactor closing subunit is used to control the slow-start contactor provided on the first branch to close, so as to The busbar is used for supplementary power; The slow-start contactor disconnection subunit is used to control the slow-start contactor to disconnect when the bus voltage is charged to a value equal to the smaller voltage value.

7. The device according to claim 5, characterized in that The charging unit is used for: If the voltage value of the second voltage is the smaller voltage value, controlling the second DC contactor on the second branch to close; When the second voltage is equal to the first voltage, closing the first DC contactor on the first branch; The bus is charged with a voltage value of the first voltage being the larger voltage value.

8. The device according to claim 5, characterized in that The charging unit is used for: If the voltage value of the first voltage is the smaller voltage value, controlling the first DC contactor on the first branch to close; When the voltage values ​​of the first voltage and the second voltage are equal, closing the second DC contactor on the second branch; The bus is charged with a voltage value of the second voltage being the larger voltage value.

9. An energy storage converter, characterized in that: include: A soft-start circuit, a first branch, a second branch and a measurement and control module; The slow-start circuit is connected in parallel only with the first branch; The battery side of the energy storage converter is connected to the positive electrode of the battery through the first branch and the second branch; The slow-start circuit is used to supplement the power of the busbar; The measurement and control module is used to obtain the voltages of the first branch, the second branch and the bus, calculate the voltage difference between the first branch and the second branch, compare the voltages of the first branch and the second branch, and control the working states of the soft-start circuit, the first branch and the second branch according to the calculation results and the comparison results.

10. The energy storage converter according to claim 9, characterized in that: The slow-start circuit includes a slow-start contactor; The slow-start contactor is connected in parallel with the first DC contactor on the first branch.

11. The energy storage converter according to claim 9, characterized in that: The second branch is provided with a second DC contactor.

12. The energy storage converter according to claim 9, characterized in that: The busbar side of the energy storage converter is connected to a busbar voltage balancing circuit.

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