Battery pack and control method thereof, energy storage system and controller

Abstract

The invention discloses a battery pack and a control method thereof, an energy storage system and a controller. A direct current-direct current conversion circuit connected with a battery cell string is arranged in the battery pack, the battery pack can autonomously boost the output voltage of the battery cell string to a preset voltage value through the direct current-direct current conversion circuit in the battery pack when reverse current exists in a power supply loop of the battery cell string, and the preset voltage value is used for offsetting the reverse current. The voltage processed by the DC-DC conversion circuit in the battery pack is only all or part of the output voltage of the battery cell string in the battery pack, and the processed voltage is obviously reduced compared with the voltage to be processed by a power converter connected with the rear stage of the battery pack in application. The loss of the power supply system comprising the battery pack and the cost of the power supply system comprising the battery pack can be effectively reduced.

Description

Technical Field

[0001] This application relates to the field of energy technology, and more specifically, to a battery pack and its control method, energy storage system and controller. Background Technology

[0002] A battery pack, as an energy storage device, supplies power to a load with its output voltage. Therefore, battery packs are widely used in energy storage systems, electric vehicles, and electronic devices. During the application of battery packs, some abnormalities may cause reverse current to appear in the power supply circuit, which can damage the load on the battery pack.

[0003] In related technologies, reverse current in the battery pack's power supply circuit is typically suppressed by improving the load on the battery pack. However, this approach increases the cost and losses of the power supply system that includes the battery pack. Summary of the Invention

[0004] This application provides a battery pack and its control method, an energy storage system, and a controller. The various aspects involved in the embodiments of this application are described below.

[0005] In a first aspect, a battery pack is provided, comprising: a cell string including a plurality of cells connected in series; a DC-DC converter circuit connected to the cell string, the DC-DC converter circuit being configured to: when a reverse current exists in the power supply circuit of the cell string, boost the output voltage of the cell string to a preset voltage value, the preset voltage value being used to counteract the reverse current.

[0006] In some embodiments, the battery cell string includes a first battery cell string and a second battery cell string. A portion of the multiple battery cells are connected in series to form the first battery cell string, and another portion of the multiple battery cells are connected in series to form the second battery cell string. A first output terminal of the first battery cell string is connected to a second output terminal of the second battery cell string, and the first output terminal of the second battery cell string forms a first output terminal of the battery pack. The DC-DC converter circuit includes a first DC-DC converter circuit. A first input terminal and a second input terminal of the first DC-DC converter circuit are respectively connected to the first output terminal and the second output terminal of the first battery cell string, and the output terminal of the first DC-DC converter circuit forms a second output terminal of the battery pack. The first DC-DC converter circuit is configured to: when the reverse current exists in the power supply circuit of the battery cell string, boost the output voltage of the first battery cell string to a first preset voltage value, and the sum of the first preset voltage value and the output voltage of the second battery cell string is the preset voltage value.

[0007] In some embodiments, the first DC-DC converter circuit includes a first inductor, a first controllable switch, a second controllable switch, and a first capacitor. The first end of the first inductor is connected to the second output end of the first battery cell string. The second end of the first inductor is connected to the first end of both the first controllable switch and the first end of the second controllable switch. The second end of the first controllable switch is connected to the first end of the first capacitor. The first end of the first capacitor is formed as the output end of the first DC-DC converter circuit. The second end of the second controllable switch and the second end of the first capacitor are both connected to the first output end of the first battery cell string.

[0008] In some embodiments, the DC-DC converter circuit further includes a second DC-DC converter circuit, wherein the first connection terminal, the second connection terminal, and the third connection terminal of the second DC-DC converter circuit are respectively connected to the first output terminal of the first battery cell string, the second output terminal of the first battery cell string, and the first output terminal of the second battery cell string. The second DC-DC converter circuit is configured to generate an equalizing current for energy transfer between the first battery cell string and the second battery cell string when the first DC-DC converter circuit boosts the output voltage of the first battery cell string.

[0009] In some embodiments, the second DC-DC converter circuit includes a second inductor, a third controllable switch, and a fourth controllable switch. The first end of the second inductor is connected to the first output end of the first battery cell string. The second end of the second inductor is connected to the first ends of both the third and fourth controllable switches. The second end of the third controllable switch is connected to the second output end of the first battery cell string. The second end of the fourth controllable switch is connected to the first output end of the second battery cell string.

[0010] In some embodiments, a first output terminal and a second output terminal of the battery pack are connected to a power converter. The battery pack further includes a controller configured to: in response to receiving an indication signal sent by the power converter, control the DC-DC conversion circuit to boost the output voltage of the battery cell string to the preset voltage value, wherein the indication signal is used to indicate the presence of the reverse current in the power supply circuit that supplies power to the power converter from the battery cell string.

[0011] In some embodiments, the first output terminal and the second output terminal of the battery pack are connected to a power converter. The battery pack also includes a current sensor and a controller. The current sensor is connected in series with the battery cell string. The controller is configured to receive a current signal detected by the current sensor and, if the current signal meets a preset condition, control the DC-DC converter circuit to boost the output voltage of the battery cell string to the preset voltage value.

[0012] In some embodiments, the preset conditions include: the current signal is a reverse current greater than or equal to a preset current value, and / or the rate of change of the current signal is greater than or equal to a preset value.

[0013] In a second aspect, a control method for a battery pack is provided, the battery pack including a cell string and a DC-DC converter circuit, the cell string including a plurality of cells connected in series, the DC-DC converter circuit being connected to the cell string, the control method including: in response to the presence of a reverse current in the power supply circuit of the cell string, controlling the DC-DC converter circuit to reduce the output voltage of the cell string to a preset voltage value, the preset voltage value being used to offset the reverse current.

[0014] In some embodiments, the battery cell string includes a first battery cell string and a second battery cell string. A portion of the multiple battery cells are connected in series to form the first battery cell string, and another portion of the multiple battery cells are connected in series to form the second battery cell string. A first output terminal of the first battery cell string is connected to a second output terminal of the second battery cell string, and the first output terminal of the second battery cell string forms a first output terminal of the battery pack. The DC-DC converter circuit includes a first DC-DC converter circuit. A first input terminal and a second input terminal of the first DC-DC converter circuit are respectively connected to the first output terminal and the second output terminal of the first battery cell string, and the output terminal of the first DC-DC converter circuit forms a second output terminal of the battery pack. Controlling the DC-DC converter circuit to boost the output voltage of the battery cell string to the preset voltage value includes: controlling the first DC-DC converter circuit to boost the output voltage of the first battery cell string to a first preset voltage value, where the sum of the first preset voltage value and the output voltage of the second battery cell string is the preset voltage value.

[0015] In some embodiments, the DC-DC converter circuit further includes a second DC-DC converter circuit, wherein the first connection terminal, the second connection terminal, and the third connection terminal of the second DC-DC converter circuit are respectively connected to the first output terminal of the first battery cell string, the second output terminal of the first battery cell string, and the first output terminal of the second battery cell string. The control method further includes: in response to the first DC-DC converter circuit boosting the output voltage of the first battery cell string, controlling the second DC-DC converter circuit to generate an equalizing current for energy transfer between the first battery cell string and the second battery cell string.

[0016] In some embodiments, the first output terminal and the second output terminal of the battery pack are connected to a power converter, and the control method further includes: in response to receiving an indication signal sent by the power converter, controlling the DC-DC conversion circuit to boost the output voltage of the battery cell string to the preset voltage value, wherein the indication signal is used to indicate that there is a reverse current in the power supply circuit of the battery cell string supplying power to the power converter.

[0017] In some embodiments, the first output terminal and the second output terminal of the battery pack are connected to a power converter. The battery pack also includes a current sensor connected in series with the battery cell string. The control method further includes: receiving a current signal detected by the current sensor, and controlling the DC-DC converter circuit to boost the output voltage of the battery cell string to a preset voltage value when the current signal meets preset conditions.

[0018] In some embodiments, the preset conditions include: the current signal is a reverse current greater than or equal to a preset current value, and / or the rate of change of the current signal is greater than or equal to a preset value.

[0019] In some embodiments, controlling the first DC-DC converter circuit to boost the output voltage of the first battery cell string to the first preset voltage value includes: stopping the supply of a drive signal to the first DC-DC converter circuit to boost the output voltage of the first battery cell string to the first preset voltage value through the passive charging of the first capacitor in the first DC-DC converter circuit; or, adjusting the duty cycle of the first DC-DC converter circuit to boost the output voltage of the first battery cell string to the first preset voltage value.

[0020] In some embodiments, controlling the DC-DC converter circuit to bring the output voltage of the battery cell string to a preset voltage value includes: stopping the supply of a drive signal to the DC-DC converter circuit to boost the output voltage of the battery cell string to the preset voltage value through the passive charging of the second capacitor in the DC-DC converter circuit; or, adjusting the duty cycle of the DC-DC converter circuit to boost the output voltage of the battery cell string to the preset voltage value.

[0021] Thirdly, an energy storage system is provided, comprising: a plurality of battery packs, at least one of the plurality of battery packs being a battery pack as described in the first aspect; and a power converter including a first side and a second side, the first side being connected to the plurality of battery packs and the second side being used to connect to a load or a voltage source.

[0022] Fourthly, a controller is provided for performing the method as described in the second aspect.

[0023] The battery pack provided in this application embodiment includes a DC-DC converter circuit connected to the cell string. When reverse current exists in the power supply circuit of the cell string, the battery pack can autonomously boost the output voltage of the cell string to a preset voltage value through the DC-DC converter circuit within the battery pack. This preset voltage value is used to offset the reverse current. Since the voltage processed by the DC-DC converter circuit in the battery pack is only all or part of the output voltage of the cell string, this processed voltage is significantly lower than the voltage processed by the power converter connected to the subsequent stage of the battery pack in application. Therefore, it can effectively reduce the losses and costs of the power supply system including the battery pack. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a battery pack provided in one embodiment of this application.

[0025] Figure 2 This is a schematic diagram of the structure of a battery pack provided in another embodiment of this application.

[0026] Figure 3 This is a schematic diagram of the structure of a battery pack provided in another embodiment of this application.

[0027] Figure 4 yes Figure 1 A possible structural diagram of the battery pack in the image.

[0028] Figure 5 yes Figure 3 A possible structural diagram of the battery pack in the image.

[0029] Figure 6 yes Figure 3 A schematic diagram of another possible structure of the battery pack.

[0030] Figure 7 yes Figure 5 A schematic diagram of a possible specific topology of the battery pack in the diagram.

[0031] Figure 8 yes Figure 6 A schematic diagram of a possible specific topology of the battery pack in the diagram.

[0032] Figure 9 This is a schematic diagram of the structure of an energy storage system provided in an embodiment of this application.

[0033] Figure 10 This is a schematic diagram of the structure of an energy storage system provided in another embodiment of this application.

[0034] Figure 11 This is a schematic diagram of the structure of a battery pack provided in another embodiment of this application.

[0035] Figure 12 This is a schematic diagram of the structure of a battery pack provided in another embodiment of this application.

[0036] Figure 13 This is a schematic diagram of the structure of a battery pack provided in another embodiment of this application.

[0037] Figure 14 This is a schematic diagram of the structure of a battery pack provided in another embodiment of this application.

[0038] Figure 15 This is a schematic diagram of the structure of an energy storage system provided in another embodiment of this application.

[0039] Figure 16 This is a flowchart illustrating the control method for a battery pack provided in an embodiment of this application. Detailed Implementation

[0040] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application should fall within the scope of protection of the present application.

[0041] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0042] A battery pack, as an energy storage device, supplies power to a load with its output voltage. Therefore, battery packs are widely used in energy storage systems, electric vehicles, and electronic devices. During the application of battery packs, some abnormalities may cause reverse current to appear in the power supply circuit, which can damage the battery pack's load.

[0043] For example, when a battery pack is used in an energy storage system, its load is typically a power converter. Since most power converters are non-isolated topologies built using single-phase cutoff semiconductor devices, when an overvoltage anomaly occurs in the voltage source connected to the power converter (such as the AC grid, DC grid, or other battery packs), it can cause a reverse current to flow from that voltage source into the battery pack through the power converter. This reverse current can lead to overheating or overcurrent in the power converter, ultimately causing it to fail.

[0044] For example, when a battery pack is used in an electric vehicle, its load is typically the motor drive system (i.e., the electric drive assembly, which includes the inverter and the drive motor). Abnormalities in the drive motor (such as motor controller software failure, position sensor malfunction, or IGBT drive signal malfunction) can cause shoot-through or incorrect commutation in the inverter bridge arm. This prevents the magnetic energy stored in the motor windings from being fed back or consumed as expected. Instead, it forms a reverse path through the freewheeling diodes in the inverter, flowing the energy back into the battery pack. In other words, this results in a reverse current in the battery pack's power supply circuit, which can damage components in the inverter. It should be noted that an inverter is a type of power converter; the term "power converter" in the following text includes inverters.

[0045] In related technologies, reverse current in the power supply circuit of the battery pack is typically suppressed by improving the load (e.g., the power converter) of the battery pack. Specifically, this can be achieved by adding an additional converter with reverse cutoff capability in the stage before the power converter (i.e., the side of the power converter connected to the battery pack).

[0046] However, power converters are typically connected to multiple battery packs. Therefore, the aforementioned reverse-cutoff converters need to handle higher operating voltage levels, leading to greater losses in these converters and consequently, higher overall losses in the power converter and power supply system. Furthermore, because these reverse-cutoff converters need to handle higher voltage levels, higher-voltage-rated semiconductor devices are required, resulting in higher overall costs for the power converter and power supply system.

[0047] In summary, the methods used in related technologies to suppress reverse current in the power supply circuit of the battery pack increase the cost and losses of the power supply system that includes the battery pack.

[0048] To address the aforementioned issues, this application proposes incorporating a DC-DC converter circuit connected to the cell string within the battery pack. The battery pack can autonomously boost the output voltage of the cell string to a preset voltage value via the DC-DC converter circuit when reverse current exists in the cell string's power supply circuit, thereby suppressing the reverse current. Since the DC-DC converter circuit in the battery pack handles only all or part of the output voltage of the cell string, this processed voltage is significantly lower than the voltage handled by the power converter connected to the downstream stage of the battery pack in application. Therefore, the losses of the DC-DC converter circuit in the battery pack are significantly lower than the losses of the power converter with reverse cutoff capability, effectively reducing the losses of the power supply system including the battery pack. Furthermore, because the DC-DC converter circuit in the battery pack handles a smaller voltage, lower-voltage semiconductor devices can be selected, which helps reduce the cost of the power supply system including the battery pack.

[0049] To facilitate understanding of this application, the following is combined with... Figures 1-3 The battery pack in the embodiments of this application is described in detail. For example... Figures 1-3 As shown, the battery pack 100 includes a cell string 110 and a DC-DC converter circuit 120.

[0050] The cell string 110 constitutes the core energy storage part of the battery pack 100. The cell string 110 can include multiple cells connected in series. This connection method allows multiple cells to share the role of output voltage. The sum of the output voltages of each cell in the multiple cells forms the output voltage that the cell string 110 can provide.

[0051] A DC-DC converter circuit 120 is connected to the battery cell string 110, and the DC-DC converter circuit 120 is used to boost the output voltage of the battery cell string 110. Specifically, in this embodiment, the DC-DC converter circuit 120 is configured to boost the output voltage of the battery cell string 110 to a preset voltage value when a reverse current exists in the power supply circuit of the battery cell string 110. The preset voltage value is used to cancel (or suppress) the reverse current. This embodiment does not specifically limit the preset voltage value, as long as the preset voltage value can cancel the reverse current. For example, when the DC-DC converter circuit 120 is connected to the first side of the power converter, the preset voltage value only needs to ensure that the voltage on the first side of the power converter is greater than or equal to the voltage on the second side of the power converter. Based on this, the preset voltage value can be the voltage on the second side of the power converter when a reverse current is generated.

[0052] In some embodiments, the presence of a detectable reverse current in the power supply circuit of the battery string 110 is considered sufficient to indicate the presence of a reverse current. In other embodiments, a reverse current is considered to exist in the power supply circuit of the battery string 110 only when the detectable current signal in the power supply circuit of the battery string 110 meets a preset condition. In still other embodiments, the presence of an indication signal in the communication system corresponding to the power supply circuit of the battery string 110, which indicates the presence of a reverse current, is sufficient to indicate the presence of a reverse current in the power supply circuit of the battery string 110. In this case, the indication signal used to indicate the presence of a reverse current in the power supply circuit of the battery string 110 can be considered as indicating the risk of a reverse current in the power supply circuit of the battery string 110, even though in reality, a detectable reverse current may not yet have been generated in the power supply circuit of the battery string 110.

[0053] The power supply circuit of the battery string 110 can be understood as the power supply circuit from the battery string 110 to the load. This power supply circuit includes the battery string 110, the load, and the connection circuit connecting the battery string 110 and the load. Therefore, the presence of reverse current in the power supply circuit of the battery string 110 can be understood as: a reverse current exists in the load, or a reverse current exists in the connection circuit connecting the battery string 110 and the load, or a reverse current exists within the battery string 110 itself. The load may include the power converter mentioned above.

[0054] This application does not specify the particular method by which the DC-DC converter circuit 120 boosts the output voltage of the battery cell string 110.

[0055] For example, the DC-DC converter circuit 120 can directly boost the output voltage of the entire battery cell string (e.g., Figure 1 and Figure 4 (As shown). Since the DC-DC converter circuit in the battery pack directly processes only the output voltage of the battery cell string, this processed voltage is significantly lower than the voltage processed by the power converter connected to the downstream stage of the battery pack in the application. Therefore, the losses of the DC-DC converter circuit in the battery pack are significantly lower than the losses of the power converter with reverse cutoff capability, thereby effectively reducing the losses of the power supply system including the battery pack. In addition, since the DC-DC converter circuit in the battery pack processes a smaller voltage, lower voltage-rated semiconductor devices can be selected, which helps to reduce the cost of the power supply system including the battery pack.

[0056] For example, the DC-DC converter circuit 120 directly boosts the output voltage of some of the cells in a series of cells forming a cell string (e.g., ...). Figure 2 and Figure 3 As shown in the diagram, this indirectly boosts the overall output voltage of the battery cell string 110. Since the DC-DC converter in the battery pack directly processes only a portion of the output voltage of the battery cell string, this processed voltage is significantly lower than the output voltage of the battery cell string. This further reduces the voltage that the power converter connected to the battery pack in the application needs to process. Therefore, the losses in the DC-DC converter in the battery pack are further reduced, thereby further reducing the losses of the power supply system including the battery pack. Furthermore, because the voltage processed by the DC-DC converter in the battery pack is further reduced, lower voltage-rated semiconductor devices can be selected compared to a DC-DC converter that directly processes the overall output voltage of the battery cell string, further reducing the cost of the power supply system including the battery pack.

[0057] In this embodiment, since the DC-DC converter circuit 120 in the battery pack processes only all or part of the output voltage of the cell string 110 in the battery pack, the loss of the DC-DC converter circuit 120 in the battery pack can be effectively reduced, thereby effectively reducing the loss of the power supply system including the battery pack. At the same time, it also allows the use of lower voltage-rated semiconductor devices in the DC-DC converter circuit of the battery pack, thereby reducing the cost of the power supply system including the battery pack.

[0058] This application does not impose specific limitations on the circuit topology of the DC-DC converter circuit 120 or its connection method with the cell string 110, as long as it can boost the output voltage of the cell string 110 in the battery pack 100.

[0059] As one possible implementation, such as Figure 1 As shown, the DC-DC converter circuit 120 is connected to both ends of the battery cell string 110 to directly boost the overall output voltage of the battery cell string. Therefore, the DC-DC converter circuit 120 can be any circuit topology that can directly boost the output voltage of the battery cell string 110. For example, the DC-DC converter circuit 120 can be a boost circuit, flyback converter circuit, forward converter circuit, or buck-boost circuit connected in series with the battery cell string 110.

[0060] As an example, such as Figure 4 As shown, the DC-DC converter circuit 120 can be a boost circuit. Specifically, the DC-DC converter circuit 120 may include an inductor L3, two controllable switches (a fifth controllable switch K5 and a sixth controllable switch K6, respectively), and a second capacitor C2. One end of the inductor L3 is connected to one end of the battery cell string 110, and the other end of the inductor L3 is connected to one end of both K5 and K6. The other end of K5 is connected to one end of the second capacitor C2, wherein one end of the second capacitor C2 also forms the first output terminal of the battery pack 100. The other ends of K6 and the other end of the second capacitor C2 are connected to the other end of the battery cell string 110, and the other end of the battery cell string 110 also forms the second output terminal of the battery pack 100. For example, the first output terminal and the second output terminal of the battery pack 100 are used to connect to a power converter. In some embodiments, Figure 4 The boost circuit in this circuit can also be called a non-isolated two-switch synchronous rectification boost circuit. The DC-DC converter circuit 120 is configured as follows: Figure 4 The structure shown is the simplest structure of the DC-DC converter circuit 120, and the control logic is simple and stable. Therefore, this method can reduce both the hardware cost and the control cost of the DC-DC converter circuit 120.

[0061] As another possible implementation, such as Figure 2 As shown, the DC-DC converter circuit 120 and a portion of the battery cells in the battery cell string 110 (i.e. Figure 2 The two ends of the first cell string BT1 are connected, and the DC-DC converter circuit 120 is used to directly boost the output voltage of the first cell string BT1, thereby indirectly boosting the output voltage of the entire cell string 110.

[0062] Specifically, such as Figure 2 As shown, the battery string 110 has a dividing point S, which divides the multiple batteries in the battery string 110 into two parts. One part of the batteries are connected in series to form a first battery string BT1, and the other part of the batteries are connected in series to form a second battery string BT2. Based on this, the battery string 110 can be understood as including the first battery string BT1 and the second battery string BT2. The two ends of the first battery string BT1 are the first output terminal and the second output terminal, respectively. The two ends of the second battery string BT2 are also the first output terminal and the second output terminal, respectively. The first output terminal of the first battery string BT1 is connected to the second output terminal of the second battery string BT2. At this time, the first output terminal of the first battery string BT1 and the second output terminal of the second battery string BT2 are equivalent to the dividing point S. The second output terminal of the first battery string BT1 and the first output terminal of the second battery string BT2 form the two ends of the battery string 110.

[0063] In some embodiments, Figure 2 The DC-DC converter circuit 120 shown may include only Figure 5 or Figure 6 The first DC-DC converter circuit 121 shown directly boosts the output voltage of the first cell string BT1. See details. Figure 5 or Figure 6 The first input terminal of the first DC-DC converter circuit 121 is connected to the first output terminal of the first cell string BT1, and the second input terminal of the first DC-DC converter circuit 121 is connected to the second output terminal of the first cell string BT1. The output terminals of the first DC-DC converter circuit 121 and the first output terminal of the second cell string BT2 respectively form the second output terminal and the first output terminal of the battery pack. Based on the connection relationship of the first DC-DC converter circuit 121, it can be understood as a converter circuit connected in series with the first cell string BT1. The first DC-DC converter circuit 121 is configured to: when there is reverse current in the power supply circuit of the cell string 110, directly boost the output voltage of the first cell string BT1 to a first preset value, thereby boosting the overall output voltage of the cell string 110 to the preset voltage value. The first preset voltage value is the sum of the first preset voltage value and the output voltage of the second cell string.

[0064] With this configuration, since the voltage directly processed by the first DC-DC converter 121 in the battery pack is only the output voltage of the first cell string, and this processed voltage is significantly lower than the overall output voltage of the cell string in the battery pack (i.e., full voltage power conversion), the loss of the first DC-DC converter 121 in the battery pack is further reduced, thereby further reducing the loss of the power supply system including the battery pack. In addition, since the voltage processed by the first DC-DC converter 121 in the battery pack is further reduced, compared with the DC-DC converter circuit that directly processes the overall output voltage of the cell string, a lower voltage-rated semiconductor device (i.e., a high-performance low-voltage switching device) can be selected. For example, considering the effects of semiconductor switching voltage spikes, the input and output voltages of the selected first DC-DC converter 121 can be lower than 200Vdc, thus further reducing the cost of the battery pack and the power supply system including the battery pack.

[0065] In this embodiment, the first DC-DC converter 121 can be a circuit topology that can directly boost the output voltage of the first battery cell string BT1. For example, the first DC-DC converter 121 can be connected in series with the first battery cell string BT1 and be a boost circuit, flyback converter circuit, forward converter circuit, or buck-boost circuit, etc.

[0066] As an example, such as Figure 7 or Figure 8 As shown, the first DC-DC converter circuit 121 is a boost circuit connected in series with the first battery cell string BT1. Specifically, the first DC-DC converter circuit 121 includes a first inductor L1, a first controllable switch K1, a second controllable switch K2, and a first capacitor C1. The first end of the first inductor L1 is connected to the second output end of the first battery cell string BT1, and the second end of the first inductor L1 is connected to the first end of both the first controllable switch K1 and the first end of the second controllable switch K2. The second end of the first controllable switch K1 is connected to the first end of the first capacitor C1, and the first end of the first capacitor C1 forms the output end of the first DC-DC converter circuit 121. The second ends of the second controllable switch K2 and the second end of the first capacitor C1 are both connected to the first output end of the first battery cell string BT1.

[0067] By configuring the first DC-DC converter circuit 121 with the above structure, the structure of the first DC-DC converter circuit 121 is simple and the control logic is simple and stable. Therefore, this method can reduce the hardware cost and control cost of the first DC-DC converter circuit 121, thereby further reducing the cost of the DC-DC converter circuit 120 containing the first DC-DC converter circuit 121.

[0068] As another possible implementation, such as Figure 3 As shown, the DC-DC converter circuit 120 is connected to both ends of the first cell string BT1 and both ends of the cell string 110. That is, the DC-DC converter circuit 120 is connected to both ends of the cell string 110 and the dividing point S within the cell string 110. At this time, the DC-DC converter circuit 120 is used to directly boost the output voltage of the first cell string BT1 while simultaneously regulating the energy of the first cell string BT1 and the second cell string BT2 to maintain energy balance between the first cell string BT1 and the second cell string BT2. This achieves indirect boosting of the overall output voltage of the cell string 110 while significantly improving the overall energy utilization rate of the cell string 110 under safe conditions.

[0069] Based on this, the DC-DC converter circuit 120 can be a circuit topology that can directly boost the output voltage of the first cell string BT1 and simultaneously perform energy balancing on the first cell string BT1 and the second cell string BT2. In some embodiments, such as Figure 5 and Figure 6 As shown, the DC-DC converter circuit 120 can include a second DC-DC converter circuit 122 in addition to the first DC-DC converter circuit 121. The connection method and topology of the first DC-DC converter circuit 121 can be as described above.

[0070] The second DC-DC converter circuit 122 is an active balancing circuit capable of transferring energy. For example, the second DC-DC converter circuit 122 is a capacitive active balancing circuit or an inductive active balancing circuit. See details... Figure 5 and Figure 6The second DC-DC converter circuit 122 includes a first connection terminal, a second connection terminal, and a third connection terminal. The first connection terminal is connected to the first output terminal of the first battery cell string, the second connection terminal is connected to the second output terminal of the first battery cell string, and the third connection terminal is connected to the first output terminal of the second battery cell string. Based on the connection method of the second DC-DC converter circuit 122, the second DC-DC converter circuit 122 can be understood as a converter circuit connected in parallel with the first battery cell string BT1 and the second battery cell string BT2. In this embodiment, the second DC-DC converter circuit 122 is configured to generate a balancing current for energy transfer between the first battery cell string BT1 and the second battery cell string BT2 when the first DC-DC converter circuit 121 boosts the output voltage of the first battery cell string BT1. In some embodiments, the equalizing current generated by the second DC-DC converter 122 can compensate for the inconsistency in the current flowing through the first DC-DC converter 121 and the second DC-DC converter 122 caused by the introduction of the first DC-DC converter 121, ensuring that the current flowing through the first DC-DC converter 121 and the second DC-DC converter 122 is within a certain deviation range. In some embodiments, it can be ensured that the current flowing through the first DC-DC converter 121 and the second DC-DC converter 122 is equal.

[0071] By simultaneously setting a first DC-DC converter circuit 121 and a second DC-DC converter circuit 122 in the DC-DC converter circuit 120, the output voltage of the first cell string BT1 can be directly boosted using the first DC-DC converter circuit 121. At the same time, during the boosting process of the first DC-DC converter circuit 121, the energy of the first cell string BT1 and the second cell string BT2 can be managed using the second DC-DC converter circuit 122 to avoid the energy imbalance of the first cell string BT1 and the second cell string BT2 caused by the first DC-DC converter circuit 121 boosting the first cell string BT1. This achieves indirect boosting of the overall output voltage of the cell string 110 while greatly improving the overall energy utilization rate of the cell string 110 under the premise of safety.

[0072] In addition, since the voltage processed by the first DC-DC converter circuit 121 is relatively low (compared to...), Figure 1 Compared to the voltage processed by the DC-DC converter circuit 120 in this application, a lower voltage-rated semiconductor switch can be selected to achieve higher efficiency and lower cost. Due to the manufacturing process of semiconductor switches, power semiconductor devices, represented by silicon-based low-voltage MOSFETs below 250V, have significant advantages over higher voltage devices in terms of switching characteristics and on-resistance. Therefore, the first DC-DC converter circuit 121 in this application is connected in series in the first battery cell string BT1, which is superior to solutions in related technologies. Figure 1The proposed solution offers lower conduction losses. The second DC-DC converter 122 only handles the power difference resulting from the addition of the first DC-DC converter 121. Therefore, the second DC-DC converter 122 has a smaller operating current and relatively smaller capacity, allowing for the selection of semiconductors with lower current and lower capacity. Furthermore, since the second DC-DC converter 122 is connected in parallel, even the use of higher voltage semiconductor switches does not result in significant conduction losses. Thus, even with the second DC-DC converter 122, higher efficiency and lower cost can still be achieved. In summary, using the first DC-DC converter 121 as the DC-DC converter circuit still ensures lower overall cost and higher efficiency for the battery pack and the power supply system containing the battery pack.

[0073] As mentioned earlier, the second DC-DC converter circuit 122 is an active equalization circuit capable of transferring energy. As an example, such as... Figure 7 and Figure 8 As shown, the second DC-DC converter circuit 122 includes a second inductor L2, a third controllable switch K3, and a fourth controllable switch K4. The first terminal of the second inductor L2 is connected to the first output terminal of the first battery cell string BT1. The second terminal of the second inductor L2 is connected to the first terminals of both the third and fourth controllable switches K3 and K4. The second terminal of the third controllable switch K3 is connected to the second output terminal of the first battery cell string BT1, and the second terminal of the fourth controllable switch K4 is connected to the first output terminal of the second battery cell string BT2.

[0074] By configuring the second DC-DC converter circuit 122 with the above structure, the structure of the second DC-DC converter circuit 122 is simple and the control logic is simple and stable. Therefore, this method can reduce the hardware cost and control cost of the second DC-DC converter circuit 122, thereby further reducing the cost of the DC-DC converter circuit 120 containing the second DC-DC converter circuit 122.

[0075] It should be noted that, in the embodiments of this application, for any single cell string or battery pack, the polarities of its first output terminal and second output terminal are opposite. For example, when the first output terminal is the negative output terminal, the second output terminal is the positive output terminal. In some embodiments, such as Figure 5 and Figure 7As shown, the first output terminal of the first cell string BT1 is connected to the second output terminal of the second cell string BT2, that is, the negative output terminal of the first cell string BT1 is connected to the positive output terminal of the second cell string BT2, and the dividing point S is equivalent to the negative output terminal of the first cell string BT1 or the positive output terminal of the second cell string BT2. At this time, it is equivalent to the first DC-DC converter circuit 121 being set at the positive output terminal of the cell string 110, and the second output terminal of the battery pack formed by the output terminal of the first DC-DC converter circuit is OUT+, and the first output terminal of the second cell string is formed as the first output terminal of the battery pack, which is OUT-. For example, when the first output terminal is the positive output terminal, the second output terminal is the negative output terminal. In some embodiments, such as... Figure 6 and Figure 8 As shown, the first output terminal of the first cell string BT1 is connected to the second output terminal of the second cell string BT2, that is, the positive output terminal of the first cell string BT1 is connected to the negative output terminal of the second cell string BT2, and the dividing point S is equivalent to the positive output terminal of the first cell string BT1 or the negative output terminal of the second cell string BT2. At this time, it is equivalent to the first DC-DC converter circuit 121 being set at the negative output terminal of the cell string 110, and the second output terminal of the battery pack formed by the output terminal of the first DC-DC converter circuit is OUT-, and the first output terminal of the second cell string is formed as the first output terminal of the battery pack, which is OUT+.

[0076] In some embodiments, to facilitate the execution of the above-described operations by the DC-DC converter 120, the first DC-DC converter 121, and the second DC-DC converter 122 in the battery pack, a controller 130 (e.g., ...) can be provided in the battery pack 110. Figure 9 and Figure 10 As shown in the figure, the corresponding conversion circuit is controlled by the controller 130 to perform the corresponding action.

[0077] For example, when there is a reverse current in the power supply circuit of the cell string 110, the DC-DC converter circuit 120 can boost the output voltage of the cell string 110 to a preset voltage value. This can be controlled by the controller 130. That is, the controller 130 in the battery pack is connected to the DC-DC converter circuit 120, and the controller 130 can respond to the presence of a reverse current in the power supply circuit of the cell string 110 by controlling the DC-DC converter circuit 120 to boost the output voltage of the cell string 110 to a preset voltage value.

[0078] In this embodiment, the method by which the controller 130 controls the DC-DC converter circuit 120 to boost the output voltage of the battery string 110 to a preset voltage value in response to the presence of reverse current in the power supply circuit of the battery string 110 is not specifically limited.

[0079] As an example, controller 130 can control DC-DC converter circuit 120 based on the indication signals described above (e.g., ...). Figure 1 and Figure 4 The DC-DC converter circuit 120 shown boosts the output voltage of the battery cell string 110 to a preset voltage value. Specifically, the controller 130 has a communication function. When the load connected to the controller 130 is a power converter, the controller 130 can be configured to: in response to receiving an indication signal sent by the power converter, control the DC-DC converter circuit 120 to boost the output voltage of the battery cell string 110 to a preset voltage value. The indication signal is described in detail below.

[0080] As another example, controller 130 can control DC-DC converter circuit 120 based on current signals detected by battery pack 110 itself (e.g., ...). Figure 1 and Figure 4 The DC-DC converter circuit 120 shown boosts the output voltage of the cell string 110 to a preset voltage value. Specifically, the battery pack 100 may include a controller 130 and a current sensor 140, wherein the current sensor 140 is connected in series with the cell string 110, and the current sensor 140 is used to detect the current signal in the cell string 110 and send the current signal to the controller 130. When the load connected to the controller is a power converter, the controller can be configured to: in response to the current signal detected by the current sensor meeting a preset condition, control the DC-DC converter circuit 120 to boost the output voltage of the cell string 110 to a preset voltage value to suppress reverse current. A detailed description of the preset conditions can be found in the following description.

[0081] For example, when there is a reverse current in the power supply circuit of the cell string 110, the first DC-DC converter circuit 121 can boost the output voltage of the first cell string BT1 to a first preset voltage value. This can be controlled by the controller 130. That is, the controller 130 in the battery pack is connected to the first DC-DC converter circuit 121, and the controller 130 can respond to the presence of a reverse current in the power supply circuit of the cell string 110 by controlling the first DC-DC converter circuit 121 to boost the output voltage of the first cell string BT1 to the first preset voltage value.

[0082] In this embodiment, the method by which the controller 130 controls the first DC-DC converter circuit 121 to boost the output voltage of the first battery string BT1 to a first preset voltage value in response to the presence of reverse current in the power supply circuit of the battery string 110 is not specifically limited.

[0083] As an example, controller 130 can control the first DC-DC converter 121 to boost the output voltage of the first cell string BT1 to a first preset voltage value based on the indication signal described above. Specifically, as... Figure 9 As shown, the controller 130 has a communication function. When the load connected to the controller 130 is a power converter, the controller 130 can be configured to: in response to receiving an indication signal sent by the power converter, control the first DC-DC conversion circuit 121 to boost the output voltage of the first cell string BT1 to a first preset voltage value.

[0084] As another example, controller 130 can control the first DC-DC converter circuit 121 to boost the output voltage of the first cell string BT1 to a first preset voltage value based on the current signal detected by the battery pack 110 itself. Specifically, as Figure 10 As shown, the battery pack 100 may include a controller 130 and a current sensor 140. The current sensor 140 is connected in series with the cell string 110 and is used to detect the current signal in the cell string 110 and send the current signal to the controller 130. When the load connected to the controller is a power converter, the controller can be configured to: in response to the current signal detected by the current sensor meeting a preset condition, control the first DC-DC conversion circuit 121 to boost the output voltage of the first cell string BT1 to a first preset voltage value to suppress reverse current.

[0085] As previously described, controller 130 can control DC-DC converter circuit 120 or first DC-DC converter circuit 121 based on an indication signal. Therefore, in some embodiments, when the load connected to controller 130 is a power converter, controller 130 can also be configured to: in response to receiving an indication signal sent by the power converter, control DC-DC converter circuit 120 to boost the output voltage of the battery cell string to a preset voltage value, or control first DC-DC converter circuit 121 to boost the output voltage of the first battery cell string to a first preset voltage value. In this embodiment, the indication signal is used to indicate the presence of reverse current in the power supply circuit that supplies power to the power converter via the battery cell string. Alternatively, the indicator signal can be used to indicate the presence of reverse current risk in the power supply circuit that supplies power to the power converter via the battery cell string. For example, when the power converter detects an overvoltage anomaly in its connected voltage source (e.g., another battery pack, AC grid, or other DC voltage source), it can send the anomaly signal (i.e., the indicator signal in this application) to the controller 130 in the battery pack via communication or dry contact. This allows the controller 130 to quickly control the DC-DC converter circuit 120 to boost the output voltage of the battery cell string 110 to a preset voltage value, or to quickly control the first DC-DC converter circuit 121 to boost the output voltage of the first battery cell string BT1 to a first preset voltage value, thereby suppressing reverse current.

[0086] By controlling the DC-DC converter 120 to boost the output voltage of the battery cell string 110 to a preset voltage value based on the indication signal sent by the power converter, or by controlling the first DC-DC converter 121 to boost the output voltage of the first battery cell string BT1 to a first preset voltage value, the reverse current can be suppressed before it is formed or just emerging, thereby preventing problems before they occur. It can not only suppress the reverse current, but also improve the suppression response speed, thus improving the safety of the power supply system including the battery pack and the power converter.

[0087] As previously mentioned, controller 130 can control DC-DC converter circuit 120 or first DC-DC converter circuit 121 based on the current signal detected by the current sensor meeting preset conditions. Therefore, in some embodiments, when the load connected to controller 130 is a power converter and the battery pack also includes current sensor 140 and controller 130, controller 130 can also be configured to: receive the current signal detected by the current sensor, and, when the current signal meets preset conditions, control DC-DC converter circuit 120 to boost the output voltage of the battery cell string to a preset voltage value, or control first DC-DC converter circuit 121 to boost the output voltage of the first battery cell string to a first preset voltage value. In the embodiments of the application, the preset condition is a criterion threshold or logic rule used by the controller to determine whether to trigger DC-DC converter circuit 120 to boost the output voltage of the battery cell string to a preset voltage value, or the preset condition is a criterion threshold or logic rule used by the controller to determine whether to trigger first DC-DC converter circuit to boost the output voltage of the first battery cell string to a first preset voltage value. In some embodiments, the current signal meets preset conditions to indicate the presence of reverse current in the power supply circuit that powers the power converter from the battery pack. In other embodiments, the current signal meets preset conditions to indicate that the reverse current in the power supply circuit that powers the power converter from the battery pack needs to be suppressed.

[0088] By controlling the DC-DC converter 120 to boost the output voltage of the cell string 110 to a preset voltage value based on the current signal detected by the battery pack itself, or by controlling the first DC-DC converter 121 to boost the output voltage of the first cell string BT1 to a first preset voltage value, the battery pack can realize the function of autonomously identifying system abnormalities. That is, the battery pack can detect the risk of reverse current without the downstream power converter. This method can still effectively suppress reverse current when communication fails, significantly improving the safety and adaptability of the system.

[0089] The embodiments of this application do not impose specific limitations on the preset conditions.

[0090] As an example, the preset conditions include: the current signal is a reverse current greater than or equal to a preset current value. That is, the current sensor can directly detect the reverse current, and the detected reverse current is greater than or equal to the preset current value. This method can effectively identify large-amplitude reverse currents, which is beneficial for detecting steady-state and slowly changing reverse currents. For the controller, the judgment is simple, direct, and easy to implement.

[0091] As another example, preset conditions include: the rate of change of the current signal is greater than or equal to a preset value. The current sensor can directly detect changes in the current signal where the rate of change is greater than or equal to the preset value. This method can detect sudden changes in reverse current in advance, providing early warning when the reverse current value reaches a dangerous level, which is beneficial for detecting reverse current caused by transient events such as lightning strikes or short circuits.

[0092] As another example, the preset conditions include: the current signal is a reverse current greater than or equal to a preset current value, and the rate of change of the current signal is greater than or equal to a preset value. This method can take into account the advantages of the preset conditions mentioned above, thereby improving the detection accuracy of reverse current, significantly reducing the probability of false triggering, and improving the accuracy of protection actions.

[0093] In this embodiment, the current sensor 140 can be connected in series at any position within the cell string 110. This application does not impose specific limitations on this, as long as the current sensor 140 can detect the current signal within the cell string 110. As examples, the series connection position of the current sensor 140 can be referenced... Figures 11-14 As shown.

[0094] In some embodiments, the battery pack 100 itself may be provided with a current sensor. The current sensor 140 mentioned in this application embodiment can be shared with the current sensor that is already present in the battery pack 100. That is, the current sensor 140 mentioned in this application embodiment is a current sensor that is already present in the battery pack 100. In other words, there is only one current sensor in the battery pack 100.

[0095] In some other embodiments, although the battery pack 100 itself may be equipped with a current sensor, the current sensor 140 mentioned in the embodiments of this application may be different from the current sensor already present in the battery pack 100. That is, the current sensor 140 mentioned in the embodiments of this application is different from the current sensor already present in the battery pack 100. In other words, there may be two current sensors in the battery pack 100.

[0096] This application embodiment does not specifically limit the method by which the controller 130 controls the DC-DC converter circuit 120 to boost the output voltage of the battery cell string 110 to a preset voltage value.

[0097] As one possible implementation, the controller 130 controls the DC-DC converter circuit 120 to boost the output voltage of the cell string 110 to a preset voltage value. Specifically, this includes: the controller 130 stopping the supply of drive signals to the DC-DC converter circuit 120, so that the second capacitor C2 (e.g., ...) can be used to boost the output voltage of the cell string 110 to a preset voltage value. Figure 4 The passive charging (as shown) boosts the output voltage of the cell string 110 to the preset voltage value.

[0098] As another possible implementation, the controller 130 controls the DC-DC converter circuit 120 to boost the output voltage of the battery cell string 110. Specifically, this includes: the controller 130 adjusting the DC-DC converter circuit 120 (e.g., ...). Figure 4 The duty cycle (as shown) is used to boost the output voltage of the cell string 110.

[0099] This application embodiment does not specifically limit the method by which the controller 130 controls the first DC-DC converter circuit 121 to boost the output voltage of the first battery cell series BT1 to a first preset voltage value.

[0100] As one possible implementation, the controller 130 controls the first DC-DC converter circuit 121 to boost the output voltage of the first cell string BT1 to a first preset voltage value. Specifically, this includes: the controller 130 stops providing drive signals to the first DC-DC converter circuit 121, so that the first capacitor C1 (e.g., ...) can be used to boost the output voltage of the first cell string BT1 to a first preset voltage value. Figure 7 and Figure 8 The passive charging (as shown) boosts the output voltage of the first cell string BT1 to the first preset voltage value.

[0101] As another possible implementation, the controller 130 controls the first DC-DC converter circuit 121 to boost the output voltage of the first battery cell string BT1. Specifically, this includes: the controller 130 adjusting the first DC-DC converter circuit 121 (e.g., ...). Figure 7 and Figure 8 The duty cycle (as shown) is adjusted to boost the output voltage of the first cell string BT1 to a first preset voltage value.

[0102] like Figures 9-10 As shown in the illustration, this application also provides an energy storage system 200. The energy storage system includes multiple battery packs 210 and a power converter 220. The power converter 220 includes a first side and a second side. The first side is connected to the multiple battery packs 210, and the second side is used to connect to a load or a voltage source. The voltage source can be, for example, a DC voltage source or an AC voltage source. The AC voltage source can be, for example, an AC power grid. The DC voltage source can be, for example, a DC power grid or a DC grid, etc. At least one of the multiple battery packs 210 is any of the battery packs 100 described above.

[0103] It should be noted that, Figures 9-10The example described uses only one example where each battery pack in the multiple battery packs 210 is the aforementioned battery pack 100 (including controller 130, or including controller 130 and current sensor 140). In practical applications, any number of battery packs in the multiple battery packs 210 of the energy storage system 200 can be replaced with the aforementioned battery pack 100. This allows for the suppression of reverse current in the power converter based on some or all of the battery packs with adjustable output voltages, thereby improving the safety of the energy storage system while reducing the overall cost and losses of the energy storage system.

[0104] In this application embodiment, the type of power converter 220 is not specifically limited. For example, the power converter 220 can be one or more of the following: inverter, power conversion system (PCS), and rectifier.

[0105] The following is combined with Figure 15 The scheme in this application is illustrated by taking the power converter in the energy storage system as a grid-connected PCS as an example. Figure 15 As shown, the voltage source connected to the grid-connected PCS is the AC power grid. In this scenario, when the battery pack 100 provided in this application embodiment is applied to the energy storage system, it can be used to protect against grid anomalies such as high voltage ride-through. Specifically, when a grid anomaly such as high voltage ride-through occurs, the grid-connected PCS undergoes overmodulation, and the grid reverse-charges the DC side of the grid-connected PCS (i.e., the battery pack 100). Because the battery impedance of the AC side grid is low, the AC side grid can also be considered as a voltage source, and the reverse charging current is uncontrolled, causing overcurrent / overheating damage to the grid-connected PCS (especially the power semiconductors within it). After applying the battery pack 100 mentioned in this application, the current sensor within the battery pack 100 can be used to identify the system anomaly. After identifying the anomaly, one possible approach is: the battery pack 10 performs wave blocking processing, passively charging the first output capacitor C1 in the first DC-DC converter circuit 210, automatically increasing the equivalent output voltage of the battery pack 10, and reducing the reverse charging current. Upon detecting an anomaly, another possible approach is to automatically adjust the first DC-DC converter circuit 210 and the second DC-DC converter circuit 220 to rapidly boost the voltage while avoiding energy imbalance within the battery pack, thereby reducing the reverse charging current. Both methods can prevent overcurrent or overheating damage to the grid-connected PCS.

[0106] It should be noted that, for the sake of simplifying the illustration, in Figures 9-15 In the middle: the first DC-DC converter circuit is labeled DC / DC1, and DC / DC1 is equivalent to... Figures 1-8 The first DC-DC converter circuit is 121. The second DC-DC converter circuit is labeled DC / DC2, where DC / DC2 is equivalent to... Figures 1-8 The second DC-DC converter circuit 122 in the circuit.

[0107] Furthermore, the controllable switch described in the embodiments of this application (e.g., the first controllable switch, the second controllable switch, the third controllable switch, or the fourth controllable switch mentioned above) refers to a semiconductor switch that can realize the function of turning on or off, such as a metal-oxide-semiconductor field-effect transistor (MOSFET), a bipolar junction transistor (BJT), etc., and the embodiments of this application do not specifically limit it.

[0108] The above text combined Figures 1 to 15 The device embodiments of this application have been described in detail below, in conjunction with... Figure 16 The method embodiments of this application are described in detail below. It should be understood that the description of the method embodiments corresponds to the description of the apparatus embodiments; therefore, any parts not described in detail can be referred to the foregoing apparatus embodiments.

[0109] like Figure 16 As shown, the battery pack control method S1600 provided in this application embodiment includes step S1610. It should be noted that the method is applied to the battery pack described above. The battery pack includes a cell string and a DC-DC converter circuit. The cell string includes multiple cells connected in series, and the DC-DC converter circuit is connected to the cell string.

[0110] See details Figure 16 In step S1610: In response to the presence of reverse current in the power supply circuit of the battery cell string, the DC-DC converter circuit is controlled to reduce the output voltage of the battery cell string to a preset voltage value, which is used to counteract the reverse current.

[0111] In some embodiments, the battery cell string includes a first battery cell string and a second battery cell string. A portion of the multiple battery cells are connected in series to form the first battery cell string, and another portion of the multiple battery cells are connected in series to form the second battery cell string. A first output terminal of the first battery cell string is connected to a second output terminal of the second battery cell string, and the first output terminal of the second battery cell string forms the first output terminal of the battery pack. The DC-DC converter circuit includes a first DC-DC converter circuit. A first input terminal and a second input terminal of the first DC-DC converter circuit are respectively connected to the first output terminal and the second output terminal of the first battery cell string, and the output terminal of the first DC-DC converter circuit forms the second output terminal of the battery pack. Controlling the DC-DC converter circuit to boost the output voltage of the battery cell string to the preset voltage value includes: controlling the first DC-DC converter circuit to boost the output voltage of the first battery cell string to a first preset voltage value, and the sum of the first preset voltage value and the output voltage of the second battery cell string is the preset voltage value.

[0112] In some embodiments, the DC-DC converter circuit further includes a second DC-DC converter circuit, wherein the first connection terminal, the second connection terminal, and the third connection terminal of the second DC-DC converter circuit are respectively connected to the first output terminal of the first battery cell string, the second output terminal of the first battery cell string, and the first output terminal of the second battery cell string. The control method further includes: in response to the first DC-DC converter circuit boosting the output voltage of the first battery cell string, controlling the second DC-DC converter circuit to generate a balancing current for energy transfer between the first battery cell string and the second battery cell string.

[0113] In some embodiments, the first output terminal and the second output terminal of the battery pack are connected to a power converter, and the control method further includes: in response to receiving an indication signal sent by the power converter, controlling the DC-DC conversion circuit to boost the output voltage of the battery cell string to the preset voltage value, wherein the indication signal is used to indicate that there is a reverse current in the power supply circuit of the battery cell string supplying power to the power converter.

[0114] In some embodiments, the first output terminal and the second output terminal of the battery pack are connected to a power converter. The battery pack also includes a current sensor connected in series with the battery cell string. The control method further includes: receiving a current signal detected by the current sensor, and, if the current signal meets a preset condition, controlling the DC-DC converter circuit 120 to boost the output voltage of the battery cell string to a preset voltage value, or controlling the first DC-DC converter circuit 121 to boost the output voltage of the first battery cell string to a first preset voltage value.

[0115] In some embodiments, the preset conditions include: the current signal is a reverse current greater than or equal to a preset current value, and / or the rate of change of the current signal is greater than or equal to a preset value.

[0116] In some embodiments, controlling the first DC-DC converter circuit to boost the output voltage of the first battery cell string to a first preset voltage value includes: stopping the supply of a drive signal to the first DC-DC converter circuit to boost the output voltage of the first battery cell string to the first preset voltage value through the passive charging of the first capacitor in the first DC-DC converter circuit; or, adjusting the duty cycle of the first DC-DC converter circuit to boost the output voltage of the first battery cell string to the first preset voltage value.

[0117] In some embodiments, controlling the DC-DC converter circuit to bring the output voltage of the battery cell string to a preset voltage value includes: stopping the supply of a drive signal to the DC-DC converter circuit to boost the output voltage of the battery cell string to the preset voltage value through the passive charging of the second capacitor in the DC-DC converter circuit; or, adjusting the duty cycle provided by the DC-DC converter circuit to boost the output voltage of the battery cell string to the preset voltage value.

[0118] This application also provides a controller that can be used to execute the methods described in the above method embodiments. This application does not limit the specific implementation of the controller. For example, the controller can be implemented in hardware when executing the above methods. Alternatively, the controller can be implemented using a combination of software and hardware. Yet another example is that the controller can be implemented in software, such as by an MCU running a computer program to execute the above methods.

[0119] This application also provides a chip, including a processor, which can be used to call and run a computer program from memory, causing a power converter or power system on which the chip is installed to perform the methods described in the above method embodiments. It is understood that the processor can be any type of processor mentioned above. It is also understood that the memory can be independent of the chip or integrated into the chip.

[0120] This application also provides a machine-readable storage medium for storing a program. This program causes a computer to execute the methods described in the various embodiments of this application.

[0121] This application also provides a computer program product. The computer program product includes a program. The program causes a computer to perform the methods described in various embodiments of this application.

[0122] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any other combination. When implemented in software, it can be implemented, in whole or in part, as 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 described in the embodiments of this disclosure exist. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a machine-readable storage medium or transmitted from one machine-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The machine-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., digital video discs (DVDs)), or semiconductor media (e.g., solid-state drives (SSDs)).

[0123] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments of this disclosure can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this disclosure.

[0124] In the several embodiments provided in this disclosure, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0125] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0126] In addition, the functional units in the various embodiments of this disclosure can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0127] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A battery pack, characterized in that, include: A battery cell string includes multiple battery cells connected in series. A DC-DC converter circuit is connected to the battery cell string. The DC-DC converter circuit is configured to boost the output voltage of the battery cell string to a preset voltage value when there is a reverse current in the power supply circuit of the battery cell string. The preset voltage value is used to counteract the reverse current.

2. The battery pack according to claim 1, characterized in that, The battery cell string includes a first battery cell string and a second battery cell string. A portion of the multiple battery cells are connected in series to form the first battery cell string, and another portion of the multiple battery cells are connected in series to form the second battery cell string. The first output terminal of the first battery cell string is connected to the second output terminal of the second battery cell string, and the first output terminal of the second battery cell string is formed as the first output terminal of the battery pack. The DC-DC converter circuit includes a first DC-DC converter circuit, the first input terminal and the second input terminal of the first DC-DC converter circuit are respectively connected to the first output terminal and the second output terminal of the first cell string, and the output terminal of the first DC-DC converter circuit is formed as the second output terminal of the battery pack. The first DC-DC converter circuit is configured to boost the output voltage of the first battery cell string to a first preset voltage value when the reverse current exists in the power supply circuit of the battery cell string, wherein the sum of the first preset voltage value and the output voltage of the second battery cell string is the preset voltage value.

3. The battery pack according to claim 2, characterized in that, The first DC-DC converter circuit includes a first inductor, a first controllable switch, a second controllable switch, and a first capacitor. The first end of the first inductor is connected to the second output end of the first battery cell string. The second end of the first inductor is connected to the first end of both the first and second controllable switches. The second end of the first controllable switch is connected to the first end of the first capacitor. The first end of the first capacitor forms the output end of the first DC-DC converter circuit. The second end of the second controllable switch and the second end of the first capacitor are both connected to the first output end of the first battery cell string.

4. The battery pack according to claim 2, characterized in that, The DC-DC converter circuit further includes a second DC-DC converter circuit. The first connection terminal, the second connection terminal, and the third connection terminal of the second DC-DC converter circuit are respectively connected to the first output terminal of the first battery cell string, the second output terminal of the first battery cell string, and the first output terminal of the second battery cell string. The second DC-DC converter circuit is configured to generate an equalizing current for energy transfer between the first battery cell string and the second battery cell string when the first DC-DC converter circuit boosts the output voltage of the first battery cell string.

5. The battery pack according to claim 4, characterized in that, The second DC-DC converter circuit includes a second inductor, a third controllable switch, and a fourth controllable switch. The first end of the second inductor is connected to the first output end of the first battery cell string. The second end of the second inductor is connected to the first ends of both the third and fourth controllable switches. The second end of the third controllable switch is connected to the second output end of the first battery cell string. The second end of the fourth controllable switch is connected to the first output end of the second battery cell string.

6. The battery pack according to claim 1, characterized in that, The first output terminal and the second output terminal of the battery pack are used to connect to a power converter. The battery pack also includes a controller configured to: in response to receiving an indication signal sent by the power converter, control the DC-DC conversion circuit to boost the output voltage of the battery cell string to the preset voltage value, wherein the indication signal is used to indicate that there is a reverse current in the power supply circuit of the battery cell string supplying power to the power converter.

7. The battery pack according to claim 1, characterized in that, The first output terminal and the second output terminal of the battery pack are connected to a power converter. The battery pack also includes a current sensor and a controller. The current sensor is connected in series with the battery cell string. The controller is configured to receive the current signal detected by the current sensor and, when the current signal meets a preset condition, control the DC-DC conversion circuit to boost the output voltage of the battery cell string to the preset voltage value.

8. The battery pack according to claim 7, characterized in that, The preset conditions include: the current signal is a reverse current greater than or equal to a preset current value, and / or the rate of change of the current signal is greater than or equal to a preset value.

9. A method for controlling a battery pack, characterized in that, The battery pack includes a battery cell string and a DC-DC converter circuit. The battery cell string includes multiple battery cells connected in series. The DC-DC converter circuit is connected to the battery cell string. The control method includes: In response to the presence of reverse current in the power supply circuit of the battery cell string, the DC-DC converter circuit is controlled to reduce the output voltage of the battery cell string to a preset voltage value, which is used to counteract the reverse current.

10. The control method according to claim 9, characterized in that, The battery cell string includes a first battery cell string and a second battery cell string. A portion of the multiple battery cells are connected in series to form the first battery cell string, and another portion of the multiple battery cells are connected in series to form the second battery cell string. A first output terminal of the first battery cell string is connected to a second output terminal of the second battery cell string. The first output terminal of the second battery cell string forms the first output terminal of the battery pack. The DC-DC converter circuit includes a first DC-DC converter circuit. A first input terminal and a second input terminal of the first DC-DC converter circuit are respectively connected to the first output terminal and the second output terminal of the first battery cell string. The output terminal of the first DC-DC converter circuit forms the second output terminal of the battery pack. The step of controlling the DC-DC converter circuit to boost the output voltage of the battery cell string to the preset voltage value includes: The first DC-DC converter circuit is controlled to boost the output voltage of the first battery cell string to a first preset voltage value, and the sum of the first preset voltage value and the output voltage of the second battery cell string is the preset voltage value.

11. The control method according to claim 10, characterized in that, The DC-DC converter circuit further includes a second DC-DC converter circuit, wherein the first connection terminal, the second connection terminal, and the third connection terminal of the second DC-DC converter circuit are respectively connected to the first output terminal of the first battery cell string, the second output terminal of the first battery cell string, and the first output terminal of the second battery cell string. The control method further includes: In response to the first DC-DC converter boosting the output voltage of the first battery cell string, the second DC-DC converter is controlled to generate a balanced current for energy transfer between the first battery cell string and the second battery cell string.

12. The control method according to claim 9, characterized in that, The first output terminal and the second output terminal of the battery pack are connected to a power converter, and the control method further includes: In response to receiving an indication signal from the power converter, the DC-DC converter is controlled to boost the output voltage of the battery cell string to the preset voltage value, wherein the indication signal is used to indicate that there is a reverse current in the power supply circuit of the battery cell string that supplies power to the power converter.

13. The control method according to claim 9, characterized in that, The first output terminal and the second output terminal of the battery pack are connected to a power converter. The battery pack also includes a current sensor connected in series with the battery cells. The control method further includes: The system receives the current signal detected by the current sensor, and when the current signal meets the preset conditions, controls the DC-DC converter circuit to boost the output voltage of the battery cell string to the preset voltage value.

14. The control method according to claim 13, characterized in that, The preset conditions include: the current signal is a reverse current greater than or equal to a preset current value, and / or the rate of change of the current signal is greater than or equal to a preset value.

15. The control method according to claim 10, characterized in that, The step of controlling the first DC-DC converter circuit to boost the output voltage of the first battery cell string to the first preset voltage value includes: Stop providing drive signals to the first DC-DC converter circuit, so that the output voltage of the first cell string is boosted to the first preset voltage value through passive charging of the first capacitor in the first DC-DC converter circuit; or, Adjust the duty cycle of the first DC-DC converter circuit to boost the output voltage of the first battery cell string to the first preset voltage value.

16. The control method according to claim 9, characterized in that, The step of controlling the DC-DC converter circuit to bring the output voltage of the battery cell string to a preset voltage value includes: Stop supplying drive signals to the DC-DC converter circuit, so that the output voltage of the battery cell string is boosted to the preset voltage value through passive charging of the second capacitor in the DC-DC converter circuit; or, Adjust the duty cycle of the DC-DC converter circuit to boost the output voltage of the battery cell string to the preset voltage value.

17. An energy storage system, characterized in that, include: A plurality of battery packs, wherein at least one of the plurality of battery packs is the battery pack according to any one of claims 1-8; A power converter includes a first side and a second side, the first side being connected to the plurality of battery packs, and the second side being used to connect to a load or voltage source.

18. A controller, characterized in that, Used to perform the control method as described in any one of claims 9-16.

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