Energy storage system, control method and apparatus, and medium

Abstract

The present application discloses an energy storage system, a control method and apparatus, and a medium. The system comprises: an inverter, a first DC / DC circuit, a second DC / DC circuit, a switch circuit, and a controller. A first end of the first DC / DC circuit and a first end of the second DC / DC circuit are connected to a battery module. A second end of the first DC / DC circuit and a second end of the second DC / DC circuit are connected in series by means of the switch circuit and then connected to a direct-current side of the inverter. When a received instruction corresponds to a third voltage interval, the controller controls the switch circuit to connect the second end of the first DC / DC circuit and the second end of the second DC / DC circuit together in parallel. The second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected together in series to operate in a corresponding second voltage interval, and an interval in which the second voltage interval overlaps the third voltage interval is a first voltage interval, such that a voltage that meets the requirements of the inverter can be outputted when the battery module is started off-grid.

Description

Energy storage system, control method, device and medium

[0001] The present application claims priority to the Chinese patent application No. 202411273539.4, filed on September 11, 2024, and entitled "Energy storage system, control method, device and medium", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of power electronics, in particular to an energy storage system, a control method, a device and a medium. BACKGROUND

[0003] The energy storage system includes a battery module and an inverter, and the direct current side of the inverter is connected to the battery module. When the battery module is working, it needs to communicate with the inverter, and according to the instructions of the inverter, the output voltage, output current and other information of the battery module are controlled.

[0004] However, more and more application scenarios require the energy storage system to have the ability to start and restore local load power supply in off-grid conditions. When the alternating current side of the inverter is off-grid, there is no power supply on the inverter side. Therefore, the inverter and the battery module cannot establish communication, and the voltage range required by the inverter for the battery module cannot be obtained. The voltage range that the battery module can output may not meet the requirements of the inverter. SUMMARY

[0005] Therefore, the present application provides an energy storage system, a control method, a device and a medium, which can output a voltage meeting the requirements of the inverter when the battery module starts off-grid.

[0006] The present application provides an energy storage system, comprising: an inverter, a first DC / DC circuit, a second DC / DC circuit, a switching circuit and a controller; the first end of the first DC / DC circuit and the first end of the second DC / DC circuit are used to connect a battery module; the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected to the direct current side of the inverter in series through the switching circuit; the controller is used to control the switching circuit to act so that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel when the instruction sent by the inverter corresponds to a third voltage interval; the second end of the first DC / DC circuit and the second end of the second DC / DC circuit work in series and correspond to a second voltage interval, and the interval in which the second voltage interval overlaps with the third voltage interval is a first voltage interval.

[0007] In a possible implementation, the controller is further configured to control the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be in series when the energy storage system is started, and control the voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be in the first voltage range, and control the switch circuit to be in a state corresponding to the second voltage range when the instruction sent by the inverter indicates the second voltage range, and control the switch circuit to be in the state corresponding to the second voltage range, and control the voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be in the second voltage range.

[0008] In a possible implementation, the switch circuit includes a first switch, a second switch, and a third switch, two ends of the first switch are connected to a positive electrode of the second end of the first DC / DC circuit and a negative electrode of the second end of the second DC / DC circuit respectively, a first end and a second end of the second switch are connected to a negative electrode of the second end of the first DC / DC circuit and a negative electrode of the second end of the second DC / DC circuit respectively, a first end and a second end of the third switch are connected to a positive electrode of the second end of the first DC / DC circuit and a positive electrode of the second end of the second DC / DC circuit respectively, and when the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series, the first switch is closed, and the second switch and the third switch are both open.

[0009] In a possible implementation, the instruction indicates that the inverter is a three-phase inverter, and the controller is further configured to control the voltage of the first DC / DC circuit and the second DC / DC circuit to be in the second voltage range.

[0010] In a possible implementation, the instruction indicates that the inverter is a single-phase inverter, and the controller is further configured to control the parallel voltage of the first DC / DC circuit and the second DC / DC circuit to be in the third voltage range after the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel.

[0011] In a possible implementation, the controller controls the switch circuit to operate such that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel, specifically, the controller controls the first switch to be open, controls the voltage of the second end of the first DC / DC circuit and the voltage of the second end of the second DC / DC circuit, controls the voltage difference between two ends of the second switch and the voltage difference between two ends of the third switch to be less than a voltage threshold, and controls the second switch and the third switch to be closed, and controls the parallel voltage of the first DC / DC circuit and the second DC / DC circuit to be in the third voltage range.

[0012] The application also provides an energy storage system, comprising: an inverter, a first DC / DC circuit, a second DC / DC circuit, a switching circuit and a controller; a first end of the first DC / DC circuit and a first end of the second DC / DC circuit are used for connecting a battery module; a second end of the first DC / DC circuit and a second end of the second DC / DC circuit are connected to a direct current side of the inverter in parallel through the switching circuit; the controller is used for receiving an instruction sent by the inverter corresponding to a second voltage interval, controlling the switching circuit to act so that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series, and controlling a series voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be in the second voltage interval; the second end of the first DC / DC circuit and the second end of the second DC / DC circuit work in parallel corresponding to a third voltage interval, and an interval in which the second voltage interval and the third voltage interval overlap is a first voltage interval.

[0013] In a possible implementation, the controller is further configured to, when the energy storage system is started, control a parallel voltage of the first DC / DC circuit and the second DC / DC circuit to be in a first voltage interval; and when receiving an instruction sent by the inverter corresponding to a third voltage interval, control a state of the switching circuit to be unchanged, and control a parallel voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be in the third voltage interval.

[0014] In a possible implementation, the switching circuit comprises: a first switch, a second switch and a third switch; two ends of the first switch are respectively connected to a positive electrode of the second end of the first DC / DC circuit and a negative electrode of the second end of the second DC / DC circuit; a first end and a second end of the second switch are respectively connected to a negative electrode of the second end of the first DC / DC circuit and a negative electrode of the second end of the second DC / DC circuit; a first end and a second end of the third switch are respectively connected to a positive electrode of the second end of the first DC / DC circuit and a positive electrode of the second end of the second DC / DC circuit; when the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel, the first switch is opened, and the second switch and the third switch are both closed.

[0015] In a possible implementation, the instruction indicates that the inverter is a single-phase inverter; and the controller is further configured to control a parallel voltage of the first DC / DC circuit and the second DC / DC circuit to be in the third voltage interval.

[0016] In a possible implementation, the instructions instruct the inverter to be a three-phase inverter; and the controller is further configured to control a series voltage of the first DC / DC circuit and the second DC / DC circuit to be within the second voltage interval after the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series.

[0017] In a possible implementation, the controller controls the switching circuit to operate such that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series, specifically: controls the first switch to be open, controls the voltage at the second end of the first DC / DC circuit and the voltage at the second end of the second DC / DC circuit, controls the voltage difference between the two ends of the second switch and the voltage difference between the two ends of the third switch to be less than a voltage threshold, and controls the second switch and the third switch to be closed; and controls the series voltage of the first DC / DC circuit and the second DC / DC circuit to be within the second voltage interval.

[0018] The application also provides a control method of an energy storage system, including an inverter, a first DC / DC circuit, a second DC / DC circuit, and a switching circuit; a first end of the first DC / DC circuit and a first end of the second DC / DC circuit are configured to be connected to a battery module; a second end of the first DC / DC circuit and a second end of the second DC / DC circuit are connected to a direct-current side of the inverter in series through the switching circuit; the method includes: receiving instructions sent by the inverter; when the instructions correspond to a third voltage interval, controlling the switching circuit to operate such that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel, and controlling the voltage at the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be within the third voltage interval; when the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series, the second end of the first DC / DC circuit and the second end of the second DC / DC circuit correspond to a second voltage interval, and an interval in which the second voltage interval overlaps with the third voltage interval is a first voltage interval.

[0019] In a possible implementation, the method further includes: when the energy storage system is started, controlling the series voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be within the first voltage interval; and when the instructions sent by the inverter correspond to the second voltage interval, controlling the switching circuit to remain unchanged, and controlling the series voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be the second voltage interval.

[0020] The application further provides a control method of an energy storage system, an inverter, a first DC / DC circuit, a second DC / DC circuit and a switch circuit; a first end of the first DC / DC circuit and a first end of the second DC / DC circuit are used for connecting a battery module; a second end of the first DC / DC circuit and a second end of the second DC / DC circuit are connected to a direct current side of the inverter in parallel through the switch circuit; the method comprises the following steps: receiving an instruction sent by the inverter; when the instruction corresponds to a second voltage interval, controlling the switch circuit to act so as to connect the second end of the first DC / DC circuit and the second end of the second DC / DC circuit together in series, and controlling a series voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be in the second voltage interval; when the second end of the first DC / DC circuit and the second end of the second DC / DC circuit work together in parallel, a third voltage interval is corresponded, and an interval in which the second voltage interval and the third voltage interval overlap is a first voltage interval.

[0021] A possible implementation manner further comprises the following steps: when the energy storage system is started, controlling a parallel voltage of the first DC / DC circuit and the second DC / DC circuit to be in a first voltage interval; when the instruction sent by the inverter corresponds to a third voltage interval, controlling the switch circuit to be in an unchanged state, and controlling a parallel voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be in the third voltage interval.

[0022] The application further provides a control device, comprising a processor and a memory, the memory is used for storing programs, instructions or codes, and the processor is used for executing the programs, instructions or codes in the memory to complete the control method of the energy storage system.

[0023] The application further provides a computer readable storage medium, which stores a computer program, and the computer program is loaded by a processor to execute the control method of the energy storage system.

[0024] The energy storage system provided by the application embodiment can start by default according to the series connection of the second ends of the two DC / DC circuits when the battery pack and the inverter are not in communication, and can determine whether to adjust the connection relationship of the second ends of the two DC / DC circuits according to the instruction of the inverter after the battery pack is started in black start mode and is in communication with the inverter. The energy storage system provided by the application embodiment does not need to stop and start again after the battery pack is started in black start mode, that is, the output voltage of the DC / DC circuit does not need to decrease to 0 after the battery pack is started in black start mode, and the input voltage of the inverter does not need to decrease to the minimum input voltage, so that the time of black start is effectively shortened, and the plug-and-play of the battery pack is realized. BRIEF DESCRIPTION OF DRAWINGS

[0025] Fig. 1 is a schematic diagram of a kind of energy storage system provided in the embodiment of the application;

[0026] Fig. 2 is a voltage interval schematic diagram of a kind of energy storage system provided in the embodiment of the application;

[0027] Fig. 3A is a schematic diagram of another kind of energy storage system provided in the embodiment of the application;

[0028] Fig. 3B is the schematic diagram of K1 closure in Fig. 3A;

[0029] Fig. 4 is a black start flow chart of a kind of energy storage system provided in the embodiment of the application;

[0030] Fig. 5 is the waveform diagram of the input voltage of corresponding inverter of Fig. 4;

[0031] Fig. 6 is a schematic diagram of another kind of energy storage system provided in the embodiment of the application;

[0032] Fig. 7 is a black start flow chart of a kind of energy storage system provided in the embodiment of the application;

[0033] Fig. 8 is the waveform diagram of the input voltage of corresponding inverter of Fig. 6;

[0034] Fig. 9 is a schematic diagram of a kind of control device provided in the embodiment of the application. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the embodiments of the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0036] The energy storage system provided in the embodiments of the present application can output a wide range of voltage, and the DC side can be started without communication with the inverter. The voltage range required by the inverter side cannot be known, therefore, the energy storage system of the present application can control the DC side to start under the requirements of low-voltage range and high-voltage range compatible with the requirements of the inverter. After the DC side is started, the DC side communicates with the inverter, and then adjusts the voltage range according to the instructions sent by the inverter.

[0037] Referring to Fig. 1, which is a schematic diagram of a kind of energy storage system provided in the embodiment of the application.

[0038] The energy storage system provided in the embodiments of the present application includes: an inverter 400, a first DC / DC circuit 100, a second DC / DC circuit 200, a switching circuit 300 and a controller (not shown in the figure).

[0039] The first end of the first DC / DC circuit 100 and the first end of the second DC / DC circuit 200 are used to connect the battery module Batt.

[0040] The second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected in series through the switching circuit 300 and then connected to the DC side of the inverter 400. The voltage at the second end of the first DC / DC circuit 100 is denoted as Vo1, and the voltage at the second end of the second DC / DC circuit 100 is denoted as Vo2.

[0041] For the sake of convenience in description, the first DC / DC circuit 100, the second DC / DC circuit 200, the switching circuit 300, and the battery module Batt are jointly referred to as a battery pack 1000. The output voltage of the battery pack 1000 is the input voltage Vinv of the inverter 400. When the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected in series, the input voltage Vinv of the inverter 400 is Vo1+Vo2. When the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected in parallel, the input voltage Vinv of the inverter 400 is Vo1=Vo2.

[0042] The controller is configured to control the switching circuit to operate such that the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected in parallel when the instruction sent by the inverter corresponds to the third voltage interval, and the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected in series when the instruction sent by the inverter corresponds to the second voltage interval.

[0043] The controller is further configured to control the switching circuit to operate such that the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected in series when the energy storage system is started, and control the switching circuit to operate such that the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected in parallel when the instruction sent by the inverter corresponds to the second voltage interval.

[0044] The series voltage of the first DC / DC circuit 100 and the second DC / DC circuit 200 is controlled to be in the first voltage interval, and it should be understood that the two second ends of the DC / DC circuits are connected in series by default to start when the battery pack is black started. As shown in FIG. 2, the first voltage interval refers to V2≤Vinv≤V3; the second voltage interval corresponds to the three-phase inverter voltage interval V2≤Vinv≤V4, and the third voltage interval corresponds to the single-phase inverter voltage interval V1≤Vinv≤V3. After the battery pack is black started, the inverter 400 has electricity and can communicate. The controller receives the instruction sent by the inverter 400, and when the instruction corresponds to the second voltage interval, since the instruction sent by the inverter 400 is to require the two second ends of the DC / DC circuits to be connected in series to provide the voltage, the state of the switch circuit 300 is not changed, and the two second ends of the DC / DC circuits are continued to be connected in series; when the instruction corresponds to the third voltage interval, that is, the instruction sent by the inverter 400 requires the two second ends of the DC / DC circuits to be connected in parallel to provide the voltage, therefore, the controller controls the switch circuit 300 to act to connect the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 in parallel.

[0045] As can be seen from FIG. 2, the first voltage interval is the interval in which the second voltage interval and the third voltage interval overlap. That is, when the battery pack is black started without communication with the inverter, the voltage is kept between V2 and V3, and no matter whether the inverter is a three-phase inverter or a single-phase inverter, the voltage will not exceed the voltage range of the inverter, and the safety of starting can be ensured.

[0046] The energy storage system provided by the embodiment of the present application can complete the black start of the battery pack without knowing whether the inverter is single-phase or three-phase, and does not need to stop during the starting process and start again.

[0047] The energy storage system provided by the embodiment of the present application can complete the black start of the battery pack without knowing whether the inverter is single-phase or three-phase, and does not need to stop during the starting process and start again.

[0048] The following describes a specific implementation manner of the switch circuit in combination with the accompanying drawings.

[0049] Referring to FIG. 3A, FIG. 3A is a schematic diagram of another energy storage system provided by the embodiment of the present application.

[0050] The energy storage system provided by the embodiment of the present application comprises a first switch K1, a second switch K2 and a third switch K3.

[0051] The two ends of the first switch are respectively connected to the positive pole of the second end of the first DC / DC circuit 100 and the negative pole of the second end of the second DC / DC circuit 200.

[0052] The first end and the second end of the second switch are respectively connected to the negative pole of the second end of the first DC / DC circuit 100 and the negative pole of the second end of the second DC / DC circuit 200.

[0053] The first end and the second end of the third switch are respectively connected to the positive pole of the second end of the first DC / DC circuit 100 and the positive pole of the second end of the second DC / DC circuit 200.

[0054] In FIG. 3B, when the energy storage system is black started, the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected in series by default, and the first switch K1 is closed, and the second switch K2 and the third switch K3 are both disconnected.

[0055] In order to simultaneously meet the input voltage range requirements of the three-phase inverter and the single-phase inverter, the two DC / DC circuits are switched between series connection and parallel connection by using the switch circuit. In this way, a smaller output voltage of the DC / DC circuit can be used to obtain a larger change range of the inverter input voltage, and the design difficulty and cost of the DC / DC circuit are reduced.

[0056] The complete process of black starting the energy storage system provided by the embodiment of the present application will be described below in combination with a flowchart.

[0057] Referring to FIG. 4, which is a black starting flowchart of an energy storage system provided by the embodiment of the present application.

[0058] S401: Start the two DC / DC circuits, and control the switch circuit to connect the second ends of the two DC / DC circuits in series, that is, close K1 and disconnect K2 and K3 as shown in FIG. 3.

[0059] S402: Control the voltages Vo1 and Vo2 of the second ends of the two DC / DC circuits respectively, and Vinv=Vo1+Vo2, which satisfies V2≤Vinv≤V3; as can be seen from FIG. 2, when V2≤Vinv≤V3, the input voltage Vinv of the single-phase inverter or the three-phase inverter meets the range requirement of the inverter input voltage, and the inverter can be started and communication with the battery pack is established.

[0060] S403: After the inverter establishes communication, the two DC / DC circuits receive the instructions sent by the inverter, and can determine whether the connected inverter is a single-phase inverter or a three-phase inverter according to the instructions.

[0061] S404: If it is determined to be a single-phase inverter according to the instructions, K1 is first disconnected. That is, the input voltage required by the single-phase inverter is lower, and the second ends of the two DC / DC circuits need to be changed from series connection to parallel connection.

[0062] The controller controls the switching circuit to operate so that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel, specifically: controlling the first switch to be open, controlling the voltage at the second end of the first DC / DC circuit and the voltage at the second end of the second DC / DC circuit, so that the voltage difference between the two ends of the second switch and the voltage difference between the two ends of the third switch are both less than a voltage threshold, and the second switch and the third switch are closed; controlling the parallel voltage of the first DC / DC circuit and the second DC / DC circuit to be within a third voltage interval. For details, please refer to S405 and S406 below.

[0063] S405: Control Vo1 and Vo2 so that the voltage difference between the two ends of K2 in the disconnected state and the voltage difference between the two ends of K3 are both less than a voltage threshold, which needs to be less than or equal to the minimum value that ensures that K2 and K3 do not stick when they are closed, for example, K1, K2 and K3 can all be relays or contactors, etc. One of the specific implementation methods can be to collect the input voltage Vinv of the inverter, control the second end voltage Vo1=Vo2=Vinv of the two-way DC / DC circuit, at this time the voltage difference between the two ends of K2 and the voltage difference between the two ends of K3 are theoretically 0, and through common closed-loop control methods, the control accuracy can be ensured to be high enough, at this time the voltage difference between the two ends of K2 and K3 can be small enough.

[0064] S406: When the voltage difference between the two ends of K2 and K3 is less than the voltage threshold, K2 and K3 can be closed.

[0065] S407: At this time, the two-way DC / DC circuit is switched to parallel mode, and the voltage instruction after starting is controlled to control the output voltage Vo1 and Vo2 of the DC / DC circuit, so that the input voltage Vinv of the inverter satisfies the second voltage interval V1≤Vinv≤V3. That is, the instruction indicates that the inverter is a single-phase inverter; the controller is also used to control the parallel voltage of the first DC / DC circuit and the second DC / DC circuit to be within a third voltage interval after the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel.

[0066] S408: If it is a three-phase inverter, the states of K1, K2 and K3 remain unchanged.

[0067] S409: controlling the output voltages Vo1 and Vo2 of the DC / DC circuits according to the voltage instruction after starting, so that the input voltage Vinv of the inverter satisfies ≤Vinv≤V4. That is, if the instruction indicates that the inverter is a three-phase inverter; the controller is further configured to control the series voltage of the first DC / DC circuit and the second DC / DC circuit to be in the second voltage interval.

[0068] Up to now, the energy storage system completes starting.

[0069] In order to intuitively understand the effect of the energy storage system provided in the embodiments of the present application, the following will be introduced in combination with a waveform diagram.

[0070] Referring to FIG. 5, the diagram is a waveform diagram of the input voltage of the inverter corresponding to FIG. 4.

[0071] The energy storage system provided in the embodiments of the present application, in the case that two DC / DC circuits are connected to a single-phase inverter, the energy storage system starts to start at T0, the second ends of the two DC / DC circuits are in series mode, the input voltage Vinv of the inverter is the sum of the voltages Vo1 and Vo2 of the two DC / DC circuits, and generally Vo1=Vo2=Vinv / 2. Control Vo1 and Vo2 so that Vinv is between V2 and V3, the inverter starts normally at T1. After starting, at T2, the two DC / DC circuits obtain the instruction of the inverter, which is a single-phase inverter, then K1 is disconnected at T2, and the output voltages of the two DC / DC circuits are controlled to rise so that Vo1=Vo2=Vinv (allowing a preset error range). At T3, the voltage difference between the two ends of K2 and the voltage difference between the two ends of K3 are small enough, for example, less than a voltage threshold, then K2 and K3 are closed, at this time, the two DC / DC circuits successfully switch to parallel mode. The two DC / DC circuits control Vinv to be between V1 and V3, and the starting is completed at T4.

[0072] The energy storage system introduced in the above embodiments, the controller controls the two DC / DC circuits to start by default in series mode, and the following introduces the controller controlling the two DC / DC circuits to start by default in parallel mode.

[0073] Referring to FIG. 6, the diagram is a schematic diagram of another energy storage system provided in the embodiments of the present application.

[0074] The difference between the energy storage system provided in the embodiments of the present application and FIG. 3 is that the two DC / DC circuits in FIG. 6 start by default in parallel mode. The energy storage system comprises an inverter 400, a first DC / DC circuit 100, a second DC / DC circuit 200, a switching circuit and a controller.

[0075] The first end of the first DC / DC circuit 100 and the first end of the second DC / DC circuit 200 are used to connect a battery module; the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected to the DC side of the inverter 400 in parallel through the switching circuit.

[0076] The controller is used to control the switching circuit to act when the instruction sent by the inverter corresponds to the second voltage interval, so that the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected in series, and the series voltage of the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 is controlled to be in the second voltage interval; when the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected in parallel, the corresponding voltage interval is the third voltage interval, and the interval in which the second voltage interval overlaps with the third voltage interval is the first voltage interval.

[0077] The controller is further used to control the parallel voltage of the first DC / DC circuit 100 and the second DC / DC circuit 200 to be in the first voltage interval when the energy storage system starts; and control the state of the switching circuit unchanged when the instruction sent by the inverter corresponds to the third voltage interval, and control the parallel voltage of the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 to be in the third voltage interval.

[0078] The controller is used to control the parallel voltage of the first DC / DC circuit 100 and the second DC / DC circuit 200 to be in the first voltage interval, receive the instruction sent by the inverter 400, control the state of the switching circuit unchanged when the instruction corresponds to the third voltage interval, control the switching circuit to act so that the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected in series when the instruction corresponds to the second voltage interval, and the first voltage interval is the interval in which the second voltage interval overlaps with the third voltage interval.

[0079] When the inverter is a three-phase inverter, the instruction sent by the inverter corresponds to the second voltage interval. When the inverter is a single-phase inverter, the instruction sent by the inverter corresponds to the third voltage interval. Each voltage interval can be referred to the introduction of FIG. 2 above, and will not be described here again.

[0080] Specifically, referring to FIG. 6, the switching circuit includes a first switch K1, a second switch K2, and a third switch K3. The two ends of the first switch K1 are respectively connected to the positive pole of the second end of the first DC / DC circuit 100 and the negative pole of the second end of the second DC / DC circuit 200. The first end and the second end of the second switch K2 are respectively connected to the negative pole of the second end of the first DC / DC circuit 100 and the negative pole of the second end of the second DC / DC circuit 200. The first end and the second end of the third switch K3 are respectively connected to the positive pole of the second end of the first DC / DC circuit 100 and the positive pole of the second end of the second DC / DC circuit 200. When the second end of the first DC / DC circuit 100 and the second end of the second DC / DC circuit 200 are connected in parallel, the first switch K1 is opened, and the second switch K2 and the third switch K3 are both closed.

[0081] The energy storage system provided in the embodiments of the present application can complete black start of the battery pack without knowing whether the inverter is single-phase or three-phase, and does not need to stop and restart during the starting process.

[0082] The energy storage system provided in the embodiments of the present application can complete black start of the battery pack without knowing whether the inverter is single-phase or three-phase, and does not need to stop and restart during the starting process.

[0083] The complete process of black start of the energy storage system provided in the embodiments of the present application will be described below in combination with a flowchart.

[0084] Referring to FIG. 7, which is a black start flowchart of an energy storage system provided in the embodiments of the present application.

[0085] The black start flowchart provided in the embodiments of the present application defaults that the inverter connected to the battery pack is a single-phase inverter, that is, the second ends of the two DC / DC circuits are connected in parallel.

[0086] S701: Start the two DC / DC circuits, and control the switching circuit to connect the second ends of the two DC / DC circuits in parallel, that is, open K1 and close K2 and K3.

[0087] S702: Control the voltage Vo1 and Vo2 of the second end of the two DC / DC circuits respectively, so that V2≤Vo1+Vo2≤V3, since Vinv=Vo1+Vo2 at this time, Vinv meets the range requirement of the input voltage of the single-phase inverter and the three-phase inverter, and the three-phase inverter or the single-phase inverter can be started, and communication with the battery pack is established.

[0088] S703: After the inverter establishes communication, the two DC / DC circuits receive the instructions sent by the inverter, and can determine whether the single-phase inverter or the three-phase inverter is connected according to the instructions.

[0089] The instructions indicate that the inverter is a three-phase inverter; the controller is further configured to, after the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series, control the series voltage of the first DC / DC circuit and the second DC / DC circuit to be within a second voltage range. The controller controls the switching circuit to act so that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series, specifically: controlling the first switch to be open, controlling the voltage of the second end of the first DC / DC circuit and the voltage of the second end of the second DC / DC circuit, so that the voltage difference between the two ends of the second switch and the voltage difference between the two ends of the third switch are both less than a voltage threshold, and the second switch and the third switch are closed; controlling the series voltage of the first DC / DC circuit and the second DC / DC circuit to be within the second voltage range. For details, see S704 and S705 below.

[0090] S704: If it is determined to be a three-phase inverter according to the instructions, online switching needs to be performed. First, K2 and K3 are opened.

[0091] S705: Control Vo1 and Vo2 so that the voltage difference between the two ends of the open K1 is less than a voltage threshold, and the voltage threshold needs to be less than or equal to the minimum value that ensures that K1 is not stuck when closed. K1 can be a relay or a contactor. One of the specific implementation methods is to collect the input voltage Vinv of the inverter, control the voltage Vo1=Vo2=Vinv / 2 of the second end of the two DC / DC circuits, and theoretically the voltage between the two ends of K1 is 0 at this time. By using a common closed-loop control method, the control accuracy can be ensured to be high enough, and the voltage between the two ends of K1 is small enough.

[0092] S706: When the voltage difference between the two ends of K1 is less than the voltage threshold, K1 can be closed.

[0093] S707: At this time, the two DC / DC circuits are switched to the series mode, and the voltage Vo1 and Vo2 of the two DC / DC circuits after starting are controlled so that the input voltage Vinv of the inverter meets V2≤Vinv≤V4.

[0094] S708: If the connected is a three-phase inverter, the states of K1, K2, K3 remain unchanged.

[0095] S709: According to the voltage instruction after starting, the output voltages Vo1 and Vo2 of the DCDC are controlled, so that the input voltage Vinv of the inverter satisfies V1≤Vinv≤V3, and the starting is completed. The instruction indicates that the inverter is a single-phase inverter; the controller is also used to control the parallel voltage of the first DC / DC circuit and the second DC / DC circuit in the third voltage interval.

[0096] Up to now, the energy storage system completes the starting.

[0097] In order to intuitively understand the effect of the energy storage system provided in the embodiments of the present application, the following will be introduced in combination with the waveform diagram.

[0098] Referring to FIG. 8, it is a waveform diagram of the input voltage of the inverter corresponding to FIG. 6.

[0099] The energy storage system provided in the embodiments of the present application, in the case of two DC / DC circuits connecting a three-phase inverter, at T0 moment, the system starts, the second ends of the two DC / DC circuits are in parallel mode, the input voltage Vinv of the inverter is equal to the output voltage of each DC / DC circuit, that is, Vinv=Vo1=Vo2. Control Vo1 and Vo2 so that Vinv is between V2 and V3, at T1 moment, the inverter starts normally. After starting, at T2 moment, the DC / DC circuit obtains the instruction sent by the inverter, and knows that the inverter is a three-phase inverter, then K2 and K3 are disconnected at T2 moment, and the output voltage of the DC / DC circuit is controlled to drop, so that Vo1=Vo2=Vinv / 2 (allowing a preset error range). At T3 moment, the voltage difference between the two ends of K1 is detected to be small enough, for example, less than a voltage threshold, then K1 is closed, at this moment, the second ends of the two DC / DC circuits are successfully switched to series mode. Two DC / DC circuits control Vinv between V2 and V4, and complete the starting at T4 moment.

[0100] Based on the energy storage system provided in the above embodiments, the embodiments of the present application also provide a control method of the energy storage system, which will be described in detail below.

[0101] Firstly, the control method of the energy storage system provided in the embodiments of the present application, the energy storage system includes: an inverter, a first DC / DC circuit, a second DC / DC circuit and a switching circuit; the first end of the first DC / DC circuit and the first end of the second DC / DC circuit are used to connect a battery module; the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected to the DC side of the inverter through the switching circuit in series;

[0102] The method defaults that the second ends of the two DC / DC circuits are started in series, and the method comprises the following steps:

[0103] receiving the instruction sent by the inverter;

[0104] when the instruction corresponds to the third voltage interval, controlling the switch circuit to operate to connect the second end of the first DC / DC circuit and the second end of the second DC / DC circuit in parallel, the voltage when the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel being in the third voltage interval; when the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series, corresponding to a second voltage interval, and the interval in which the second voltage interval and the third voltage interval overlap is a first voltage interval.

[0105] The implementation process of the first control method introduced above can be specifically seen from the introduction of Fig. 4 above, and will not be described here again.

[0106] Secondly, the control method of the energy storage system provided by the embodiment of the application, the inverter, the first DC / DC circuit, the second DC / DC circuit and the switch circuit; the first end of the first DC / DC circuit and the first end of the second DC / DC circuit are used for connecting the battery module; the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected to the direct current side of the inverter in parallel through the switch circuit;

[0107] The method defaults that the second ends of the two DC / DC circuits are started in parallel, and the method comprises the following steps:

[0108] receiving the instruction sent by the inverter;

[0109] when the instruction corresponds to the second voltage interval, controlling the switch circuit to operate to connect the second end of the first DC / DC circuit and the second end of the second DC / DC circuit in series, the series voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit being in the second voltage interval; when the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel, corresponding to a third voltage interval; and the interval in which the second voltage interval and the third voltage interval overlap is a first voltage interval.

[0110] The implementation process of the second control method introduced above can be specifically seen from the introduction of Fig. 7 above, and will not be described here again.

[0111] In a possible implementation, referring to Fig. 9, which is a schematic diagram of a control device provided by the embodiment of the application.

[0112] The control device can include a memory 1011 and a processor 1012. The processor 1012 can be connected with the power converter and can drive the switches in each power conversion circuit in the power converter. As shown in FIG. 9, the memory can be a random access memory (RAM), a flash memory, a read only memory (ROM), an EPROM memory, an Electronic Programmable ROM (EPROM), a register, a hard disk, a removable disk, etc.

[0113] The memory 1011 can store computer instructions, which, when executed by the processor 1012, can be used to perform the control method of the energy storage system. The memory 1011 can also store data, such as the voltage threshold and other information involved in the above embodiments.

[0114] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware, or any combination thereof. When implemented by software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions according to the embodiments of the present application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions can be transferred from one website, computer, server or data center to another website, computer, server or data center through wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) mode. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. integrated with one or more available media. The available media can be a magnetic medium (such as a floppy disk, a hard disk, a magnetic tape), or a semiconductor medium (such as a solid state disk (SSD)), etc.

[0115] The embodiments of the present application also provide a readable storage medium for storing the method provided by the above embodiments. For example, random access memory (RAM), flash memory, read only memory (ROM), EPROM memory, non-volatile read only memory (Electronic Programmable ROM, EPROM), register, hard disk, removable disk or any other form of storage medium in the art.

[0116] It should be noted that the various embodiments described in the specification are progressive, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to each other. For the method disclosed in the embodiments, since it corresponds to the product embodiments disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the product embodiments.

[0117] The above description of disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An energy storage system, characterized by, The application relates to a power supply system comprising an inverter, a first DC / DC circuit, a second DC / DC circuit, a switch circuit and a controller. A first end of the first DC / DC circuit and a first end of the second DC / DC circuit are used for connecting a battery module. A second end of the first DC / DC circuit and a second end of the second DC / DC circuit are connected to a direct-current side of the inverter in series through the switch circuit. The controller is used for controlling the switch circuit to operate so that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel when an instruction sent by the inverter corresponds to a third voltage interval; the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series when operating, and correspond to a second voltage interval; and the second voltage interval and the third voltage interval overlap to form a first voltage interval. The controller is further used for controlling the series voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be within the first voltage interval when the energy storage system starts; and controlling the switch circuit to be in an unchanged state and the series voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be the second voltage interval when the instruction sent by the inverter corresponds to the second voltage interval.

2. The energy storage system of claim 1, wherein, The switch circuit comprises a first switch, a second switch and a third switch.

3. The energy storage system of claim 1 or 2, wherein, Two ends of the first switch are respectively connected to a positive electrode of the second end of the first DC / DC circuit and a negative electrode of the second end of the second DC / DC circuit. A first end and a second end of the second switch are respectively connected to a negative electrode of the second end of the first DC / DC circuit and a negative electrode of the second end of the second DC / DC circuit. A first end and a second end of the third switch are respectively connected to a positive electrode of the second end of the first DC / DC circuit and a positive electrode of the second end of the second DC / DC circuit. When the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series, the first switch is closed, and the second switch and the third switch are both disconnected. The instruction indicates that the inverter is a three-phase inverter.

4. The energy storage system of any one of claims 1-3, wherein, The controller is further used for controlling the series voltage of the first DC / DC circuit and the second DC / DC circuit to be within the second voltage interval. The instruction indicates that the inverter is a single-phase inverter.

5. The energy storage system of any one of claims 1-3, wherein, The controller is further used for controlling the parallel voltage of the first DC / DC circuit and the second DC / DC circuit to be within the third voltage interval after the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel. The controller controls the switch circuit to operate so that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel, and the operation specifically comprises:

6. The energy storage system of claim 3, wherein, ​ controlling the first switch to be open, controlling the voltage at the second end of the first DC / DC circuit and the voltage at the second end of the second DC / DC circuit, so that the voltage difference across the second switch and the voltage difference across the third switch are both less than a voltage threshold, and closing the second switch and the third switch; and controlling the parallel voltage of the first DC / DC circuit and the second DC / DC circuit to be within the third voltage interval.

7. An energy storage system characterized by, The application comprises: an inverter, a first DC / DC circuit, a second DC / DC circuit, a switch circuit, and a controller; a first end of the first DC / DC circuit and a first end of the second DC / DC circuit are configured to be connected to a battery module; a second end of the first DC / DC circuit and a second end of the second DC / DC circuit are connected to a DC side of the inverter in parallel through the switch circuit; the controller is configured to, when receiving an instruction sent by the inverter corresponding to a second voltage interval, control the switch circuit to operate so that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series, and control the series voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be within the second voltage interval; when the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel, the second voltage interval and the third voltage interval overlap to form a first voltage interval.

8. The energy storage system of claim 7, wherein, The controller is further configured to, when the energy storage system is started, control the parallel voltage of the first DC / DC circuit and the second DC / DC circuit to be within a first voltage interval; and when receiving an instruction sent by the inverter corresponding to a third voltage interval, control the switch circuit to remain unchanged, and control the parallel voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit to be within the third voltage interval.

9. An energy storage system according to claim 7 or 8, characterised in that, The switch circuit comprises: a first switch, a second switch, and a third switch. The first end and the second end of the first switch are respectively connected to the positive electrode of the second end of the first DC / DC circuit and the negative electrode of the second end of the second DC / DC circuit. The first end and the second end of the second switch are respectively connected to the negative electrode of the second end of the first DC / DC circuit and the negative electrode of the second end of the second DC / DC circuit. The first end and the second end of the third switch are respectively connected to the positive electrode of the second end of the first DC / DC circuit and the positive electrode of the second end of the second DC / DC circuit. When the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel, the first switch is open, and the second switch and the third switch are both closed.

10. An energy storage system according to any of claims 7-9, characterised in that, The instruction indicates that the inverter is a single-phase inverter. The controller is further configured to control the parallel voltage of the first DC / DC circuit and the second DC / DC circuit to be within the third voltage interval.

11. An energy storage system according to any of claims 7-9, characterised in that, The instruction indicates that the inverter is a three-phase inverter. The controller is further configured to control the series voltage of the first DC / DC circuit and the second DC / DC circuit to be within the second voltage range after the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series.

12. The energy storage system of claim 9, wherein, The controller controls the switching circuit to operate so that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series, specifically: The first switch is controlled to be closed, the voltage at the second end of the first DC / DC circuit and the voltage at the second end of the second DC / DC circuit are controlled to be less than a voltage threshold, and the second switch and the third switch are controlled to be closed; and the series voltage of the first DC / DC circuit and the second DC / DC circuit is controlled to be within the second voltage range.

13. A control method of an energy storage system, characterized by, The method comprises: An inverter, a first DC / DC circuit, a second DC / DC circuit, and a switching circuit; the first end of the first DC / DC circuit and the first end of the second DC / DC circuit are configured to be connected to a battery module; The second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected to the DC side of the inverter in parallel through the switching circuit; The method comprises: Receiving an instruction sent by the inverter; When the instruction corresponds to a third voltage range, the switching circuit is controlled to operate so that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel, and the voltage at the second end of the first DC / DC circuit and the second end of the second DC / DC circuit is controlled to be within the third voltage range; when the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series, the second end of the first DC / DC circuit and the second end of the second DC / DC circuit correspond to a second voltage range, and the interval in which the second voltage range overlaps with the third voltage range is a first voltage range.

14. The control method according to claim 13, characterized by The method further comprises: When the energy storage system is started, the series voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit is controlled to be within the first voltage range; when the instruction sent by the inverter corresponds to the second voltage range, the state of the switching circuit is controlled to be unchanged, and the series voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit is controlled to be the second voltage range.

15. A control method of an energy storage system, characterized by, An inverter, a first DC / DC circuit, a second DC / DC circuit, and a switching circuit; the first end of the first DC / DC circuit and the first end of the second DC / DC circuit are configured to be connected to a battery module; The second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected to the DC side of the inverter in parallel through the switching circuit; The method comprises: Receiving an instruction sent by the inverter; When the instruction corresponds to the second voltage interval, the switch circuit is controlled to operate so that the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in series, and the series voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit is controlled to be in the second voltage interval; when the second end of the first DC / DC circuit and the second end of the second DC / DC circuit are connected in parallel, the second voltage interval and a third voltage interval overlap to form a first voltage interval.

16. The control method according to claim 15, characterized by Further comprising: When the energy storage system is started, the parallel voltage of the first DC / DC circuit and the second DC / DC circuit is controlled to be in a first voltage interval; When the instruction corresponds to a third voltage interval, the switch circuit is controlled to remain unchanged, and the parallel voltage of the second end of the first DC / DC circuit and the second end of the second DC / DC circuit is controlled to be in the third voltage interval.

17. A control device characterized by comprising: The control method comprises the following steps: receiving an instruction sent by the inverter; and controlling the switch circuit to operate according to the instruction.

18. A computer-readable storage medium, characterized in that, The computer program is loaded by a processor to execute the control method of the energy storage system according to any one of claims 13-16.

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