Energy storage device and power supply system

Abstract

This application provides an energy storage device and a power supply system. The energy storage device includes two battery packs, two switching transistors, and an inductor. Each battery pack includes at least one battery cell. The two battery packs are connected in series, the two switching transistors are connected in series, and the two series-connected switching transistors are connected in parallel with the two series-connected battery packs. One end of the inductor is connected to the series connection point of the two battery packs, and the other end of the inductor is connected to the series connection point of the two switching transistors. The energy storage device is used to: control the two switching transistors to alternately conduct multiple times when the temperature of the battery packs is lower than a preset temperature threshold, so that in each of N consecutive first cycles, one battery pack charges the other battery pack, and in each of M consecutive second cycles, the other battery pack charges one of the battery packs. This application can achieve heating of the energy storage device without adding external components, which can reduce the size of the energy storage device, reduce the structural complexity of the energy storage device, and has good applicability.

Description

Technical Field

[0001] This application relates to the field of charging, and more particularly to an energy storage device and a power supply system. Background Technology

[0002] With the rapid development of energy storage devices, they are widely used in energy storage and other fields. However, when using energy storage devices in low-temperature environments, the charging rate, charging efficiency, and lifespan of the devices are significantly reduced. Currently, heating films or heaters can be installed inside the energy storage module to raise the temperature of the device and charge it, thereby improving the charging rate and efficiency. However, this approach requires the addition of external components such as heating films or heaters, increasing the size and structural complexity of the energy storage device. Summary of the Invention

[0003] This application provides an energy storage device and a power supply system that can heat the energy storage device without adding external components, thereby reducing the size and structural complexity of the energy storage device and making it more applicable.

[0004] In a first aspect, an energy storage device is provided, comprising two battery packs, two switching transistors, and an inductor. Each battery pack includes at least one battery cell. The two battery packs are connected in series, the two switching transistors are connected in series, and the two series-connected switching transistors are connected in parallel with the two series-connected battery packs. One end of the inductor is connected to the series connection point of the two battery packs, and the other end of the inductor is connected to the series connection point of the two switching transistors. The energy storage device is used to: when the temperature of the battery packs is lower than a preset temperature threshold, control the two switching transistors to alternately conduct multiple times, so that in each of N consecutive first cycles, one battery pack charges the other battery pack, and in each of M consecutive second cycles, the other battery pack charges one of the battery packs, where N and M are both integers greater than or equal to 1.

[0005] In this embodiment, by controlling two switching transistors to conduct alternately, the two battery packs can be charged and discharged alternately. Whether one battery pack charges the other or the other charges one battery pack, heating of both battery packs can be achieved. The Joule heating effect of the battery pack is used to self-heat the battery pack during the entire heating process. Heating of the energy storage device can be achieved without adding external devices, which can reduce the size of the energy storage device, reduce the structural complexity of the energy storage device, and has good applicability.

[0006] Furthermore, by controlling the values ​​of N and M, the charge of the larger battery pack can be transferred to the smaller battery pack, thereby balancing the charge of the two battery packs and facilitating the normal charging or discharging of the energy storage device.

[0007] In conjunction with the first aspect, in one embodiment, the energy storage device is configured to: when one group of battery packs is charging another group of battery packs, control the other group of battery packs to charge one of the battery packs upon reaching a preset condition. The preset condition includes at least one of the following: the remaining charge of one group of battery packs is less than a preset charge, or the depth of discharge of one group of battery packs reaches a preset depth of discharge, or the charging time of one group of battery packs to the other group of battery packs reaches a preset duration.

[0008] This avoids the situation where one battery pack is almost completely discharged while continuing to charge another battery pack during the charging process of one battery pack. This reduces the probability of one battery pack's remaining power dropping below the preset level, thereby improving the performance of one battery pack and extending its lifespan.

[0009] In conjunction with the first aspect, in one embodiment, the energy storage device further includes two first capacitors. The two first capacitors are connected in series, and the two series-connected first capacitors are connected in parallel with the two series-connected battery packs; the series connection point of the two first capacitors is connected to the series connection point of the two battery packs, and the series connection point of the two first capacitors is also connected to one end of an inductor.

[0010] In this embodiment, since the switching transistor generates ripple during operation, the first capacitor designed in this application can filter out the ripple generated by the switching transistor during operation, thereby making the current on the battery pack more stable. This can prevent the performance of the energy storage device from being reduced due to ripple current flowing through the battery pack, thereby extending the life of the energy storage device.

[0011] In conjunction with the first aspect, in one embodiment, the energy storage device further includes two first switches, one of which is connected in series with one of the first capacitors, and the other of which is connected in series with the other first capacitor.

[0012] In this way, the energy storage device can flexibly control the closing or opening of the two first switches according to the actual scenario, and can control the continuity of the current flowing through different battery packs. That is, the current of the battery pack connected in parallel with the closed first switch is relatively continuous, while the current of the battery pack connected in parallel with the open first switch is discontinuous, thus making it suitable for different scenarios.

[0013] Furthermore, when the preset temperature thresholds of the two battery packs are different, by controlling the first switch connected in parallel to the battery pack with the larger temperature difference to close and the first switch connected in parallel to the battery pack with the smaller temperature difference to open, the heating rates of the two battery packs during the heating process can be made different. This allows the two battery packs to reach their respective temperature thresholds after heating, ensuring that the energy storage device can charge or discharge at a suitable temperature. This can improve the charging or discharging rate of the energy storage device, prevent performance damage to the energy storage device, and thus improve the charging or discharging performance and reliability of the energy storage device, thereby extending the life of the energy storage device.

[0014] In conjunction with the first aspect, in one embodiment, the energy storage device is configured to: control N to be greater than M when the amplitude of the current from one battery pack to the other battery pack is equal to the amplitude of the current from the other battery pack to one battery pack, or when the discharge voltage of one battery pack is greater than the discharge voltage of the other battery pack; or, when N equals M, control the amplitude of the current from one battery pack to the other battery pack to be greater than the amplitude of the current from the other battery pack to one battery pack.

[0015] In this way, after N first cycles and M second cycles of charging and discharging, the charge of one battery pack decreases while the charge of the other battery pack increases. This reduces the charge difference between the two battery packs, thus preventing abnormal charging or discharging due to a large charge difference and ensuring the normal charging or discharging of the energy storage device. Furthermore, it also prevents charging or discharging failures that may occur due to an excessive charge difference between the two battery packs, thereby extending the lifespan of the energy storage device.

[0016] In conjunction with the first aspect, in one embodiment, the energy storage device is further configured to: control N to be less than M when the amplitude of the current from one battery pack to the other battery pack is equal to the amplitude of the current from the other battery pack to one battery pack, or when the discharge voltage of one battery pack is less than the discharge voltage of the other battery pack, in the case where the capacity of one battery pack is less than the capacity of the other battery pack or when the discharge voltage of one battery pack is less than the discharge voltage of the other battery pack; or, when N equals M, control the amplitude of the current from one battery pack to the other battery pack to be less than the amplitude of the current from the other battery pack to one battery pack.

[0017] In this way, after N first cycles and M second cycles of charging and discharging, the charge of one battery pack increases while the charge of the other battery pack decreases. This reduces the charge difference between the two battery packs, thus preventing abnormal charging or discharging due to a large charge difference and ensuring the normal charging or discharging of the energy storage device. Furthermore, it also prevents charging or discharging failures that may occur due to an excessive charge difference between the two battery packs, thereby extending the lifespan of the energy storage device.

[0018] In conjunction with the first aspect, in one embodiment, the energy storage device includes a DC-DC converter circuit and a second switch. The DC-DC converter circuit includes two switching transistors and an inductor. One end of the second switch is connected to the other end of the inductor, and the other end of the second switch is connected to the series connection point of two battery packs. The energy storage device is further configured to: control the second switch to close when the temperature of the battery pack is lower than a preset temperature threshold; and control the second switch to open when the temperature of the battery pack is greater than or equal to the preset temperature threshold.

[0019] In this embodiment, the two switching transistors and one inductor can be components of the DC-DC converter circuit of the energy storage device. When the temperature of the battery pack is lower than a preset temperature threshold, the energy storage device can control the second switch to close. By controlling the on / off state of the two switching transistors, heating of the two battery packs can be achieved. When the temperature of the energy storage device in the battery pack is higher than the preset temperature threshold, the energy storage device can control the second switch to open. By controlling the on / off state of the two switching transistors, charging or discharging of the energy storage device can be achieved. This design allows the switching transistors and inductors in the DC-DC converter circuit of the energy storage device to be reused for heating the battery pack, eliminating the need for additional dedicated switching transistors and inductors for heating the battery pack. This simplifies the internal design of the energy storage device, reduces costs, and improves economic efficiency.

[0020] In conjunction with the first aspect, in one embodiment, the DC-DC converter circuit further includes two additional switching transistors connected in series, and the two additional switching transistors connected in series are connected in parallel with the two switching transistors. One end of the inductor is also connected to the series connection point of the two additional switching transistors. The energy storage device is used to: when the second switch is off, and when the energy storage device is connected to a load or an external power source, control one of the two switching transistors to be normally on and control the other two switching transistors to be alternately turned on.

[0021] In this embodiment, when the second switch is off, the energy storage device can discharge or charge through the DC-DC converter circuit. By controlling one of the two switching transistors to be constantly on and controlling the other two switching transistors to be alternately on, the energy storage device can achieve boost / buck discharge when connected to a load; and it can achieve boost / buck charging when connected to an external power source. This ensures the normal operation of the energy storage device's discharge or charging and improves the reliability of the energy storage device's discharge or charging.

[0022] Secondly, an energy storage device is provided, comprising two battery packs, two switching transistors, and an inductor. Each battery pack includes at least one battery cell. The two battery packs are connected in series, the two switching transistors are connected in series, and the two series-connected switching transistors are connected in parallel with the two series-connected battery packs. One end of the inductor is connected to the series connection point of the two battery packs, and the other end of the inductor is connected to the series connection point of the two switching transistors. The energy storage device is used to: when the capacities of the two battery packs are unequal, control the two switching transistors to alternately conduct multiple times, so that in each of P consecutive third cycles, the battery pack with the larger capacity charges the battery pack with the smaller capacity.

[0023] In this embodiment, by controlling the two switching transistors to alternately turn on and off multiple times, the capacity difference between the two battery packs can be reduced. Thus, when the energy storage device discharges or charges, the reduced difference in the capacity of the two battery packs prevents abnormal charging or discharging caused by a large difference in the capacity of the two battery packs, ensuring the normal charging or discharging of the energy storage device. Moreover, it can also prevent charging or discharging failures caused by an excessive difference in the capacity of the two battery packs, thereby extending the lifespan of the energy storage device.

[0024] In conjunction with the second aspect, in one embodiment, the energy storage device is configured to: first control the switching transistor connected in parallel with one of the battery packs to turn on, and then control the switching transistor connected in parallel with the other battery pack to turn on, when the capacity of one battery pack is greater than the capacity of the other battery pack.

[0025] This ensures that the larger capacity battery pack charges the smaller capacity battery pack, thereby reducing the difference in charge between the two battery packs. When the energy storage device discharges or charges, the reduced difference in charge between the two battery packs prevents abnormal charging or discharging that could be caused by a large difference in charge, ensuring the normal charging or discharging of the energy storage device. Furthermore, it also prevents charging or discharging failures that could be caused by an excessive difference in charge between the two battery packs, thus extending the lifespan of the energy storage device.

[0026] Thirdly, a power supply system is provided, including a DC-DC conversion circuit and an energy storage device as described in the first aspect, the second aspect, or any possible embodiment of the first aspect. When the power supply system includes multiple energy storage devices, the multiple energy storage devices are connected in parallel, and the multiple energy storage devices connected in parallel are connected to the DC-DC conversion circuit.

[0027] In conjunction with the third aspect, in one embodiment, the power supply system further includes a power supply module and a power conversion circuit connected to the power supply module, the power conversion circuit and the DC-DC conversion circuit being used to connect to a load.

[0028] For the technical effects that the third aspect may achieve, please refer to the description of the technical effects that can be achieved in any of the possible embodiments of the first or second aspect above, which will not be repeated here. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a base station applied in a 5G communication system, provided as an embodiment of this application.

[0030] Figures 2 to 6 A schematic diagram of an energy storage device provided in an embodiment of this application.

[0031] Figure 7 This is a schematic diagram of the control signal timing for the switching transistor provided in an embodiment of this application.

[0032] Figure 8 This is a schematic diagram showing the current corresponding to each battery pack and inductor at different times, as provided in the embodiments of this application.

[0033] Figure 9 A schematic diagram of the energy storage device provided for the implementation of this application.

[0034] Figure 10 For the corresponding Figure 9 A schematic diagram showing the current of each battery pack and inductor at different times.

[0035] Figures 11 to 15 A schematic diagram of the energy storage device provided for the implementation of this application.

[0036] Figure 16 For the corresponding Figure 11 A schematic diagram showing the current of each battery pack and inductor at different times.

[0037] Figures 17 to 19 A schematic diagram of the energy storage device provided for the implementation of this application.

[0038] Figures 20 to 21 This is a schematic diagram of a power supply system provided in an embodiment of this application. Detailed Implementation

[0039] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0040] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. "And / or" in this document is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone.

[0041] The prefixes such as "first" and "second" used in this application embodiment are merely for distinguishing different descriptive objects and do not limit the position, order, priority, quantity, or content of the described objects. The use of ordinal numbers and other prefixes used to distinguish descriptive objects in this application embodiment does not constitute a limitation on the described objects. The description of the described objects is given in the claims or the context of the embodiments, and should not constitute unnecessary limitations due to the use of such prefixes. Furthermore, in the description of this embodiment, unless otherwise stated, "multiple" means two or more.

[0042] Figure 1 This is a schematic diagram of the structure of a base station 20 applied in a 5G communication system according to an embodiment of this application.

[0043] See Figure 1 The base station 20 may include a bandwidth-based unit (BBU) (not shown in the figure), a remote radio unit (RRU) 21, an active antenna unit (AAU) 22, an antenna device 23, and a power supply device 24.

[0044] The BBU can be connected to RRU21 and AAU22 via optical fiber. The BBU is the core equipment in base station 20, mainly responsible for the processing and modulation of digital signals, and transmitting the processed digital signals to RRU21 and AAU22 via optical fiber.

[0045] RRU21 can be electrically connected to antenna device 23 via feeder 26. RRU21 is primarily responsible for modulating and amplifying the digital signal from BBU into a radio frequency (RF) signal, and then transmitting the amplified RF signal to antenna device 23 via feeder 26, whereby antenna device 23 transmits the RF signal. Alternatively, RRU21 can also receive RF signals from antenna device 23 via feeder 26, demodulate the RF signal, and then transmit it to BBU.

[0046] The RRU21 typically includes an intermediate frequency (IF) unit, a transceiver unit, a power amplifier unit, and a power supply unit. The IF unit performs modulation and demodulation, digital up / down conversion, and D / A conversion on the digital signal, converting it into an IF analog signal. The transceiver unit converts this IF analog signal into a radio frequency (RF) signal. The power amplifier unit amplifies the RF signal. The power supply unit provides power to both the transceiver unit and the power amplifier unit.

[0047] AAU22 can be formed by integrating RRU21 and part of antenna equipment 23 into one unit, thus combining the structure and function of RRU21 and antenna equipment 23.

[0048] The power supply unit 24 can be connected to the BBU, RRU21, and AAU22 via bus 25 to supply power to the BBU, RRU21, and AAU22. The power supply unit 24 may include an alternating current-to-direct current (AC-DC) converter to convert the AC voltage value from the power grid (e.g., 220V AC mains power) into a negative DC voltage value before supplying it to the BBU, RRU21, and AAU22. Furthermore, the energy storage unit 27 can also supply power to the BBU, RRU21, and AAU22 via bus 25.

[0049] It should be understood that the above Figure 1 As just one example, in one possible instance, the energy storage device 27 and the power supply device 24 can be an integrated unit, thereby Figure 1 It includes only the power supply unit 24, which supplies power to the BBU, RRU21 and AAU22.

[0050] In practical use, such as Figure 1 As shown, base station 20 can be a distributed base station. RRU21, AAU22, and antenna equipment 23 can be installed on the top of tower 210; alternatively, RRU21, AAU22, and antenna equipment 23 can be installed on a rooftop 220, or at other high locations such as mountains. BBU and power supply unit 24 can be installed on the top of tower 210 or in a remote equipment room 230.

[0051] With the rapid development of energy storage devices, they are widely used in energy storage and other fields. However, when using energy storage devices in low-temperature environments, the charging rate, charging efficiency, and lifespan all decrease significantly. Currently, heating films or heaters can be installed inside the energy storage module to raise the temperature of the device and charge it, thereby improving the charging rate and efficiency. However, this approach requires external components such as heating films or heaters, increasing the size and structural complexity of the energy storage device.

[0052] Based on this, this application provides an energy storage device that can achieve heating of the energy storage device without adding external components, which can reduce the size of the energy storage device, reduce the structural complexity of the energy storage device, and has good applicability.

[0053] like Figure 2 The diagram illustrates an energy storage device provided in this application. The device includes two battery packs B1 and B2, two switching transistors Q1 and Q2, and an inductor L. Each battery pack includes at least one battery cell. The two battery packs B1 and B2 are connected in series, as are the two switching transistors Q1 and Q2. The two series-connected switching transistors Q1 and Q2 are connected in parallel with the two series-connected battery packs B1 and B2. One end of the inductor L is connected to the series connection point of the two battery packs B1 and B2, and the other end of the inductor L is connected to the series connection point of the two switching transistors Q1 and Q2.

[0054] The number of cells in the two battery packs B1 and B2 can be equal or unequal, without restriction. In practical scenarios, the two battery packs can be obtained by processing the multi-stage series-connected cells in the energy storage device. For example, taking an energy storage device with 16 stages of series-connected cells as an example, these 16 stages can be divided into two groups of 8 stages, thus obtaining two battery packs B1 and B2; or, the 16 stages can be divided into two groups of 6 stages and 10 stages, respectively, thus obtaining two battery packs B1 and B2. Moreover, the cells in each battery pack are connected in series, and the two battery packs can be connected to each other via power lines.

[0055] The switching transistor in the embodiments of this application can be a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT), or a giant transistor (GTR), or a gallium nitride (GaN) high electron mobility transistor (HEMT), etc. Figure 2 Taking IGBTs as an example, the switching transistor is used in this example.

[0056] In this embodiment of the application, the energy storage device is used to: control two switching transistors Q1 and Q2 to alternately conduct multiple times when the temperature of the battery pack is lower than a preset temperature threshold, so that in each of the N consecutive first cycles, one group of battery packs charges the other group of battery packs, and in each of the M consecutive second cycles, the other group of battery packs charges one group of battery packs, where N and M are both integers greater than or equal to 1.

[0057] The battery pack temperature can be collected by a temperature monitor. When the battery pack temperature is below a preset temperature threshold, the battery pack needs to be heated; when the battery pack temperature is above or equal to the preset temperature threshold, the battery pack does not need to be heated. This preset temperature threshold can be the preset energy storage device temperature when the battery pack needs to be heated, heated for charging, or heated for discharging. This preset temperature threshold can be determined by the battery pack's cell materials and the battery pack's operating state (such as charging / discharging or offline).

[0058] In this embodiment, when the battery pack temperature is below a preset temperature threshold, the energy storage device can control the on / off state of two switching transistors Q1 and Q2 to allow the two battery packs to charge alternately. For example, taking one battery pack as B1 and the other as B2, if the energy storage device controls the switching transistor Q1 to be on, battery pack B1 will charge battery pack B2 in each first cycle; if the energy storage device controls the switching transistor Q2 to be on, battery pack B2 will charge battery pack B1 in each second cycle. Whether battery pack B1 charges battery pack B2 or battery pack B2 charges battery pack B1, both battery packs can be heated. The Joule heating effect of the battery packs is used for self-heating during the entire heating process, eliminating the need for external components to heat the energy storage device. This reduces the size and structural complexity of the energy storage device, making it more versatile. Furthermore, by controlling the values ​​of N and M, the charge of the larger battery pack can be transferred to the smaller battery pack, balancing the charge of the two battery packs and facilitating normal charging or discharging of the energy storage device.

[0059] It is understandable that by controlling the alternating conduction of the two switching transistors Q1 and Q2, the two battery packs B1 and B2 can be self-heated. When the temperature of the battery pack reaches the preset temperature threshold, the switching transistors Q1 and Q2 are turned off to prevent the battery packs B1 and B2 from charging or discharging each other.

[0060] The first cycle in this application includes a first discharge period and a first charging period. During the first discharge period, one group of battery packs discharges, and during the second charging period, the other group of battery packs charges.

[0061] In this embodiment, during the first discharge period of the first cycle, switch Q1 is turned on while switch Q2 is turned off. This allows current to flow from the positive terminal of battery pack B1 through switch Q1 and inductor L back to the negative terminal of battery pack B1. Figure 3 As shown. During this process, because current flows in battery pack B1, the Joule heat generated by the internal impedance of battery pack B1 heats the battery pack. Simultaneously, while battery pack B1 is self-heating, it charges the inductor L (i.e., the current in inductor L increases) until the end of the first discharge period. After the inductor L stores energy, control switch Q1 is turned off and control switch Q2 is turned on, allowing the inductor L to continue charging battery pack B2. The current in inductor L gradually decreases, thus allowing the inductor L to charge battery pack B2 during the first charging period of the first cycle, as shown. Figure 4 As shown. During this process, because current flows in battery pack B2, the Joule heat generated by the internal impedance of battery pack B2 heats battery pack B2.

[0062] It should be understood that the specific implementation method for controlling the charging and discharging of the battery pack in the second to the Nth first cycles can be referred to the specific implementation method for controlling the charging and discharging of the battery pack in the first cycle mentioned above. For the sake of simplicity, it will not be repeated here.

[0063] Similarly, the second cycle includes a second discharge period and a second charging period, during which another battery pack discharges and during the second charging period, one of the battery packs charges.

[0064] In this embodiment, during the first discharge period of the first second cycle, switch Q2 is turned on while switch Q1 is turned off. This allows current to flow from the positive terminal of battery pack B2, through inductor L and switch Q2, back to the negative terminal of battery pack B2. Figure 5 As shown. During this process, because current flows in battery pack B2, the Joule heat generated by the internal impedance of battery pack B2 heats battery pack B2. Simultaneously, while battery pack B2 is self-heating, it charges the inductor L (i.e., the current in inductor L increases) until the end of the second discharge period. After the inductor L stores energy, control switch Q2 is turned off, and control switch Q1 is turned on, allowing the inductor L to continue charging battery pack B1. The current in inductor L gradually decreases, thus allowing the inductor L to charge battery pack B1 during the second charging period of the first second cycle, as shown. Figure 6 As shown. During this process, because current flows in battery pack B1, the Joule heat generated by the internal impedance of battery pack B1 heats battery pack B1.

[0065] It should be understood that the specific implementation method for controlling the charging and discharging of the battery pack in the second to the Mth second cycles can be referred to the specific implementation method for controlling the charging and discharging of the battery pack in the first second cycle mentioned above. For the sake of simplicity, it will not be repeated here.

[0066] The duration of the first cycle, the number of first cycles N, the duration of the second cycle, and the number of second cycles M in this application are related to the parameters of the energy storage device. These parameters may include, but are not limited to, the battery pack voltage, battery pack temperature, battery pack internal resistance, battery pack capacity, and the pulse current required for battery pack heating (i.e., the battery pack's heating capacity). The frequency and amplitude of the pulse current required for battery pack heating can be determined by the battery pack's temperature, capacity, and internal resistance.

[0067] It should be understood that, in the embodiments of this application, by setting an appropriate number of first cycles N and second cycles M, the heating speed and efficiency of the battery pack can be improved. This is because when the number of first cycles N and second cycles M is small, a high-frequency pulse current is generated between the two sets of battery cells. Since the reactance of the DC impedance in the battery pack is generally much greater than that of the AC impedance, the high-frequency pulse current mainly acts on the AC impedance. Due to the small reactance of the AC impedance, the heating speed and efficiency are low. When the number of first cycles N and second cycles M is large, although a low-frequency pulse current is generated between the two sets of battery cells, which can improve the heating speed and efficiency of the battery pack, continuous heating with a low-frequency pulse current may cause chemical changes in the battery pack, such as the deposition of metallic lithium on the anode surface, causing irreversible damage to the battery pack and reducing the safety of the energy storage device. Therefore, in practical scenarios, the appropriate number of first cycles N and second cycles M for battery pack heating can be determined through testing. This can improve the heating speed and efficiency of the battery pack while preventing lithium deposition, thus improving the safety of the energy storage device.

[0068] It should be noted that in the embodiments of this application, the frequency f2 of the pulse current generated between the two battery packs is related to the switching frequency f1 of the two switching transistors Q1 and Q2. For example, when N = M = 1, battery pack B1 discharges once and battery pack B2 charges once in one first cycle, and battery pack B2 discharges once and battery pack B1 charges once in one second cycle. During this charging and discharging process, the frequency f2 of the pulse current generated between the two battery packs is 2 * f1. When N = 1 and M = 2, battery pack B1 discharges once and battery pack B2 charges once in one first cycle, and battery pack B2 discharges twice and battery pack B1 charges twice in two second cycles. During this charging and discharging process, the frequency f2 of the pulse current generated between the two battery packs is 3 * f1. When N = M = 2, battery pack B1 discharges twice and battery pack B2 charges twice within two first cycles, and battery pack B2 discharges twice and battery pack B1 charges twice within two second cycles. During this charging and discharging process, the frequency of the pulse current generated between the two battery packs is f2 = 4 * f1. Therefore, even if the switching frequencies of the two switching transistors Q1 and Q2 are fixed at f1, the frequency f2 of the pulse current generated between the two battery packs satisfies the relationship: f1 ≥ 2 * f2, thus enabling heating of the two battery packs with pulse current of any frequency. In other words, by controlling N and M, the control period T2 of the two switching transistors during the charging and discharging cycle T1 between the two battery packs satisfies T1 ≤ 1 / 2 * T2. This allows for flexible adjustment of the relationship between T1 and T2, thereby enabling charging and discharging functions between the two battery packs at any cycle.

[0069] It should also be noted that the embodiments of this application do not specifically limit the relative magnitude of the duty cycles of the two switching transistors. This is because the relative magnitude of the duty cycles of the two switching transistors is related to multiple factors, such as the temperature and materials of the battery pack, and the static voltage of the battery pack (static voltage can be understood as the voltage of the battery pack when it is not heated).

[0070] In one embodiment, taking one battery pack as B1 and another battery pack as B2 as an example, the energy storage device is used to: when one battery pack B1 is charging the other battery pack B2, control the other battery pack B2 to charge one of the battery packs B1 when a preset condition is met. The preset condition includes at least one of the following: the remaining charge of one battery pack B1 is less than a preset charge; or the depth of discharge of one battery pack B1 reaches a preset depth of discharge; or the charging time of one battery pack B1 to the other battery pack B2 reaches a preset duration.

[0071] The following explanation uses the example of a battery pack having less than a preset charge level as a case study.

[0072] Specifically, the energy storage device can first control the switching transistor Q1 to conduct, and then control the switching transistors Q1 and Q2 to conduct alternately multiple times, allowing battery pack B1 to charge battery pack B2. This gradually reduces the charge level of battery pack B1 and gradually increases the charge level of battery pack B2. When the remaining charge level of battery pack B1 is less than a preset level, with the switching transistor Q2 conducting, the duty cycle of Q2 is controlled to be greater than the duty cycle of Q2 in the first cycle. This, along with the alternating conduction of Q1 and Q2, allows battery pack B2 to charge battery pack B1, further reducing the charge level of battery pack B2 and gradually increasing the charge level of battery pack B1. The advantage of this design is that it avoids the situation where battery pack B1 is completely discharged but continues to charge battery pack B2 during the charging process. This reduces the probability of the remaining charge level of battery pack B1 falling below the preset level, thereby improving the performance and extending the lifespan of battery pack B1.

[0073] The following text combines Figure 7 This section details the alternating charging and discharging of the two battery packs.

[0074] Figure 7 The diagram shows the timing sequence of the control signals for switching transistors Q1 and Q2. For ease of description, the following explanation will use an example with the first cycle being T1 (where T1 includes (t1+t2)) and the second cycle being T2 (where T2 includes (t3+t4)). Reference Figure 7 The diagram shows four first cycles and four second cycles. During the first discharge time period t1 of the first cycle, a high-level signal is input to the control electrode of switch Q1, and a low-level signal is input to the control electrode of switch Q2, thus turning Q1 on and Q2 off. The current flow inside the energy storage device is as described above. Figure 3 As shown. During the first charging time period t2 of the first cycle, a low-level signal is input to the control electrode of switch Q1, and a high-level signal is input to the control electrode of switch Q2, thereby turning off Q1 and turning on Q2. Thus, the current flow inside the energy storage device is as described above. Figure 4 As shown. The control method for the second to fourth first cycles is similar to that for the first first cycle, thus the current flow direction inside the energy storage device is as follows during the four first cycles: Figure 3 and Figure 4 As shown, and Figure 3 and Figure 4 They appear alternately.

[0075] At the end of the first charging period of the fourth first cycle, the control continues to input a low level to the control electrode of switch Q1 and a high level to the control electrode of switch Q2, as follows. Figure 7During the first discharge period t3 of the first second cycle shown in the diagram, Q1 remains off and Q2 remains on, thus the current flow inside the energy storage device is as follows: Figure 5 As shown. During the second charging time period t4 of the first second cycle, a low-level input is sent to the control electrode of switch Q2, and a high-level input is sent to the control electrode of switch Q1, thus turning on Q1 and turning off Q2. Therefore, the current flow inside the energy storage device is as follows: Figure 6 As shown. The control method for the second to fourth second cycles is similar to that for the first second cycle, thus the current flow direction inside the energy storage device is as follows during the four second cycles: Figure 5 and Figure 6 As shown, and Figure 5 and Figure 6 They appear alternately.

[0076] In the above process, the current diagrams for inductor L, battery pack B1, and battery pack B2 are as follows: Figure 8 As shown, where, Figure 8 In the diagram, (a) represents the current in inductor L. Figure 8 In the diagram, (b) represents the current of battery pack B1. Figure 8 (c) in the figure represents the current of battery pack B2.

[0077] Specifically, during the first discharge period t1 of the first cycle, battery pack B1 charges inductor L, causing the current in battery pack B1 to gradually increase, and the current flowing through inductor L also gradually increases until the end of the first discharge period. During the first charging period t2 of the first cycle, inductor L charges battery pack B2, causing the current in inductor L to gradually decrease, and the current in battery pack B2 also gradually decreases until the end of the first charging period. The trends in the energy changes of the inductor and battery pack during the second to fourth cycles are consistent with those of the first cycle and will not be elaborated further.

[0078] During the first discharge period t3 of the first second cycle, battery pack B2 charges inductor L, causing the current in battery pack B2 to gradually increase, and the current flowing through inductor L also gradually increases until the end of the first discharge period. During the first charging period t4 of the first second cycle, inductor L charges battery pack B1, causing the current in inductor L to gradually decrease, and the current in battery pack B1 also gradually decreases until the end of the first charging period. The trends in the energy changes of the inductor and battery pack during the second to fourth second cycles are consistent with those of the first first cycle and will not be described further.

[0079] In one embodiment, such as Figure 9As shown, the energy storage device also includes two first capacitors C1 and C2. The two first capacitors C1 and C2 are connected in series, and the two first capacitors C1 and C2 connected in series are connected in parallel with the two battery packs B1 and B2 connected in series; the series connection point of the two first capacitors C1 and C2 is connected to the series connection point of the two battery packs B1 and B2, and the series connection point of the two first capacitors C1 and C2 is also connected to one end of the inductor L.

[0080] In this embodiment, since the switching transistor generates ripple during operation, capacitors C1 and C2 are designed to filter out the ripple generated by the switching transistor during operation, thereby making the current on the battery pack more stable. This can prevent the performance of the energy storage device from being reduced due to ripple current flowing through the battery pack, thereby extending the life of the energy storage device.

[0081] It should be noted that the first capacitors C1 and C2 can also absorb the current generated by the lead inductance (i.e., the inductance on the power line) or parasitic inductance (such as the inductance in the cell pack). When the inductance of the lead inductance and parasitic inductance in the energy storage device is large, the current generated by the inductance of the power line between battery pack B1 and C1 can be absorbed by capacitor C1 when the switch Q1 changes from the on state to the off state. When the inductance of the lead inductance and parasitic inductance in the energy storage device is small, it can be absorbed by the equivalent capacitance of the switch itself. For example, when the switch Q1 changes from the on state to the off state, the current generated by the inductance of the power line between battery pack B1 and Q1 can be absorbed by the parasitic capacitance of switch Q1 (not shown in the figure).

[0082] Figure 9 The corresponding current diagrams for inductor L, battery pack B1, and battery pack B2 are all... Figure 10 As shown.

[0083] refer to Figure 10 It can be seen that within N first cycles T1, the current charging inductor L from battery pack B1 and the current charging battery pack B2 from inductor L are relatively stable; within M second cycles T2, the current charging inductor L from battery pack B2 and the current charging battery pack B1 from inductor L are relatively stable. This is because capacitor C1 can filter out the ripple generated during the operation of switching transistor Q1, and capacitor C2 can filter out the ripple generated during the operation of switching transistor Q2, thus the current flowing through battery packs B1 and B2 and inductor L is relatively smooth in each time period.

[0084] In one embodiment, such as Figure 11 As shown, the energy storage device also includes two first switches S1 and S2. One of the first switches S1 and S2 is connected in series with one of the first capacitors C1, and the other first switch S2 is connected in series with the other first capacitor C2.

[0085] In practical scenarios, the energy storage device (or its controller) can flexibly control the opening and closing of the first switches S1 and S2, thus resulting in different currents flowing through different battery packs. Taking the case where the first switch S1 is closed and the first switch S2 is open as an example, before the switching transistors Q1 and Q2 are turned on, because the first switch S1 is closed, battery pack B1 charges the first capacitor C1, making the voltage of battery pack B1 the same as the voltage of capacitor C1. When battery pack B1 charges battery pack B2, the control transistor Q1 is turned on, and at this time, the switching transistor Q2 is in the off state. Battery pack B1 and capacitor C1 discharge simultaneously. That is, the current in battery pack B1 flows out from the positive terminal, through the switching transistor Q1 and inductor L, back to the negative terminal of battery pack B1. Simultaneously, the current in capacitor C1 flows out from one end of capacitor C1, through the switching transistor Q1 and inductor L, back to the other end of capacitor C1. Figure 12 As shown. During this process, battery pack B1 charges inductor L (i.e., the current in inductor L increases) until the end of the first discharge period. After inductor L stores energy, control switch Q1 is turned off and control switch Q2 is turned on, allowing battery pack B2 to be charged through the freewheeling current of inductor L. The current in inductor L gradually decreases, thus enabling inductor L to charge battery pack B2 during the first charging period of the first cycle. Figure 13 As shown.

[0086] When battery pack B2 charges battery pack B1, control switch Q2 is turned on, while switch Q1 is turned off. Therefore, current flows from the positive terminal of battery pack B2, through inductor L and switch Q2, back to the negative terminal of battery pack B2. Figure 14 As shown. During this process, battery pack B2 charges inductor L (i.e., the current in inductor L increases) until the end of the second discharge period. After inductor L stores energy, control switch Q2 is turned off, and control switch Q1 is turned on, allowing battery pack B1 and capacitor C1 to be charged via the freewheeling current from inductor L. The current in inductor L gradually decreases, thus allowing inductor L to charge battery pack B1 and capacitor C1 during the second charging period of the first second cycle. Figure 15 As shown.

[0087] The timing sequence of the control signals for switching transistors Q1 and Q2 is as described above. Figure 7 As shown in the diagram, the current diagrams for inductor L, battery pack B1, and battery pack B2 in this scenario are as follows. Figure 16 As shown, where, Figure 16 In the diagram, (a) represents the current in inductor L. Figure 16 In the diagram, (b) represents the current of battery pack B1. Figure 16 (c) in the figure represents the current of battery pack B2.

[0088] Specifically, during the first discharge time period t1 of the first cycle, battery pack B1 and capacitor C1 simultaneously charge inductor L. The current in battery pack B1 gradually increases, and the current flowing through inductor L also gradually increases until the end of the first discharge time period. During time t1, because battery pack B1 and capacitor C1 charge inductor L simultaneously, the current in inductor L is greater than the current in battery pack B1 at any given moment. During the first charging time period t2 of the first cycle, inductor L charges battery pack B2. The current in inductor L gradually decreases, and the current in battery pack B2 also gradually decreases until the end of the first charging time period. During time t2, because the first switch S1 is closed, battery pack B1 can charge capacitor C1, thus current flows through battery pack B1. The trends in the energy changes of the inductor and battery pack during the second to fourth cycles are consistent with those of the first cycle and will not be elaborated further.

[0089] During the first discharge period t3 of the first second cycle, battery pack B2 charges inductor L, causing the current in battery pack B2 to gradually increase, and the current flowing through inductor L also gradually increases until the end of the first discharge period. During period t3, because the first switch S1 is closed, battery pack B1 can continue to charge capacitor C1, thus current flows through battery pack B1. During the first charging period t4 of the first second cycle, inductor L charges battery pack B1 and capacitor C1, causing the current in inductor L to gradually decrease, and the current in battery pack B1 also gradually decreases until the end of the first charging period. During period t4, because inductor L is charging battery pack B1 and capacitor C1, the current in inductor L is greater than the current in battery pack B1 at any given time. The trends in the energy changes of the inductor and battery pack during the second to fourth second cycles are consistent with those of the first first cycle and will not be described further.

[0090] Furthermore, the heating rate of the two battery packs can be controlled by turning the two first switches on or off. Taking a preset temperature threshold of T0 for battery pack B1 and a preset temperature of T0' for battery pack B2 as an example, assuming the temperature of battery pack B1 is T1 and the temperature of battery pack B2 is T2, T1 < T0, T2 < T0', and assuming T0 - T1 > T0' - T2, that is, the temperature difference of battery pack B1 is larger and the temperature difference of battery pack B2 is smaller, then during the heating process, the heating rate of battery pack B1 can be controlled to be greater than the heating rate of battery pack B2.

[0091] Specifically, the energy storage device can control the switch S1 connected in parallel with battery pack B1 to close, and the switch S2 connected in parallel with battery pack B2 to open. Thus, during the charging process from battery pack B1 to battery pack B2, when battery pack B1 discharges and inductor L stores energy, due to the closure of switch S1, the peak-to-peak current flowing through battery pack B1 (e.g., ...) Figure 16The difference between ΔI1 shown in (b) is small, and the current flowing through battery pack B1 is continuous, thus this current is a low-frequency pulse current; when inductor L releases energy and battery pack B2 is charged, since switch S2 is open, the peak-to-peak current flowing through battery pack B2 (such as...) Figure 16 The difference between ΔI2 shown in (c) is large, and the current flowing through battery pack B2 is discontinuous, thus this current is a high-frequency pulse current. As mentioned above, the reactance of the DC impedance in the battery pack is generally much greater than the reactance of the AC impedance. The low-frequency pulse current mainly acts on the DC impedance, while the high-frequency pulse current mainly acts on the AC impedance. Therefore, battery pack B1 generates more Joule heat, while battery pack B2 generates less Joule heat, resulting in a greater heating rate for battery pack B1 than for battery pack B2.

[0092] During the charging process from battery pack B2 to battery pack B1, when battery pack B2 discharges and inductor L stores energy, the current flowing through battery pack B2 is a high-frequency pulse current because switch S2 is open. When inductor L releases energy and battery pack B1 charges, the current flowing through battery pack B1 is a low-frequency pulse current because switch S1 is closed. Therefore, the heating rate of battery pack B1 is still greater than that of battery pack B2.

[0093] In summary, regardless of whether battery pack B1 is charging battery pack B2 or vice versa, the heating rate of battery pack B1 is greater than that of battery pack B2. This ensures that both battery packs reach their respective temperature thresholds after heating, guaranteeing that the energy storage device charges or discharges at the appropriate temperature. This improves the charging or discharging rate of the energy storage device, prevents performance degradation, enhances its charging or discharging performance and reliability, and ultimately extends its lifespan.

[0094] refer to Figure 16 As can be seen, by controlling the closing or opening of switches S1 and S2, the circuit topology in the energy storage device can be modified, thereby enabling flexible switching of different envelopes of current when the battery pack is heated.

[0095] Continue to refer to the above. Figure 2In one embodiment, when the capacity Q1 of one battery pack B1 is greater than the capacity Q2 of another battery pack B2, or when the discharge voltage of one battery pack B1 is greater than the discharge voltage of another battery pack B2: when the amplitude of the current from one battery pack B1 to the other battery pack B2 is equal to the amplitude of the current from the other battery pack B2 to one battery pack B1, N is controlled to be greater than M; or, when N equals M, the amplitude of the current from one battery pack B1 to the other battery pack B2 is controlled to be greater than the amplitude of the current from the other battery pack B2 to one battery pack B1.

[0096] In this embodiment, when the amplitude of the current charging battery pack B1 to battery pack B2 is equal to the amplitude of the current charging battery pack B2 to battery pack B1, and N is designed to be greater than M, the overall charging time from battery pack B1 to battery pack B2 is greater than the overall charging time from battery pack B2 to battery pack B1. Therefore, after N first cycles and M second cycles of charging and discharging, a portion of the charge in battery pack B1 will be transferred to battery pack B2. Alternatively, when N = M, this application designs the amplitude of the current charging battery pack B1 to battery pack B2 to be greater than the amplitude of the current charging battery pack B2 to battery pack B1. Therefore, when the charge from battery pack B1 to battery pack B2 in N first cycles is greater than the charge from battery pack B2 to battery pack B1 in M ​​second cycles, a portion of the charge in battery pack B1 will be transferred to battery pack B2 after N first cycles and M second cycles of charging and discharging. This reduces the charge of battery pack B1 and increases the charge of battery pack B2, thereby reducing the charge difference between battery pack B1 and battery pack B2. This prevents abnormal charging or discharging caused by a large charge difference between the two battery packs, ensuring normal charging or discharging of the energy storage device. Furthermore, it also prevents charging or discharging failures caused by an excessive charge difference between the two battery packs, thus extending the lifespan of the energy storage device.

[0097] In one embodiment, when the capacity Q1 of one battery pack B1 is less than the capacity Q2 of another battery pack B2, or when the discharge voltage of one battery pack B1 is less than the discharge voltage of another battery pack B2: when the amplitude of the current from one battery pack B1 to the other battery pack B2 is equal to the amplitude of the current from the other battery pack B2 to one battery pack B1, N is controlled to be less than M; or, when N equals M, the amplitude of the current from one battery pack B1 to the other battery pack B2 is controlled to be less than the amplitude of the current from the other battery pack B2 to one battery pack B1.

[0098] When the amplitude of the current from battery pack B1 charging battery pack B2 is equal to the amplitude of the current from battery pack B2 charging battery pack B1, this application designs N to be less than M. Thus, the overall charging time from battery pack B1 to battery pack B2 is less than the overall charging time from battery pack B2 to battery pack B1. Therefore, after N first cycles and M second cycles of charging and discharging, some of the charge in battery pack B2 will be transferred to battery pack B1. Alternatively, when N = M, this application can design the amplitude of the current from battery pack B1 charging battery pack B2 to battery pack B2 to be less than the amplitude of the current from battery pack B2 to battery pack B1. Thus, the amount of charge from battery pack B1 to battery pack B2 in N first cycles is less than the amount of charge from battery pack B2 to battery pack B1 in M ​​second cycles. Therefore, after N first cycles and M second cycles of charging and discharging, some of the charge in battery pack B2 will be transferred to battery pack B1. This increases the charge of battery pack B1 and decreases the charge of battery pack B2, thereby reducing the charge difference between battery pack B1 and battery pack B2. This prevents abnormal charging or discharging caused by a large charge difference between the two battery packs, ensuring normal charging or discharging of the energy storage device. Furthermore, it also prevents charging or discharging failures caused by an excessive charge difference between the two battery packs, thus extending the lifespan of the energy storage device.

[0099] It should be noted that N and M can be different in each charge / discharge cycle and can be adjusted in real time as needed.

[0100] In one embodiment, such as Figure 17 As shown, the energy storage device includes a DC-DC converter circuit 310 and a second switch S3. The DC-DC converter circuit 310 includes two switching transistors Q1 and Q2 and an inductor L. One end of the second switch S3 is connected to the other end of the inductor L, and the other end of the second switch S3 is connected to the series connection point of the two battery packs.

[0101] In this embodiment of the application, the energy storage device is further configured to: control the second switch S3 to close when the temperature of the battery pack is less than a preset temperature threshold; and control the second switch S3 to open when the temperature of the battery pack is greater than or equal to the preset temperature threshold.

[0102] When the second switch S3 is closed, the battery packs B1 and B2 can be heated by controlling the alternating conduction of switching transistors Q1 and Q2, thus meeting the heating requirements of battery packs B1 and B2. When the temperature of the battery packs reaches a preset temperature threshold, the second switch S3 is opened. When the second switch S3 is open, the voltage conversion of the energy storage device can be achieved by controlling the conduction or cutoff of switching transistors Q1 and Q2, which is beneficial to the normal charging or discharging of the energy storage device. This design can reuse the switching transistors Q1 and Q2 and the inductor L in the DC-DC converter circuit of the energy storage device to heat the battery pack, eliminating the need for additional switching transistors and inductors specifically for heating the battery pack. This simplifies the internal design of the energy storage device, reduces costs, and improves economic efficiency.

[0103] Figure 18 Compared to the energy storage device shown Figure 17 The energy storage device shown includes switches S1 and S2, capacitors C1 and C2, and capacitor C0. Switches S1 and S2 and capacitors C1 and C2 are the same as those described above. Figure 13 The switches S1 and S2 and capacitors C1 and C2 have the same function, so I will not repeat them here.

[0104] The function of capacitor C0 is to filter out the ripple generated by switching transistors Q1 and Q2 during the operation of the energy storage device when switches S1, S2 and S3 are all open. This makes the charging or discharging current of the energy storage device more stable, prevents the performance degradation of the energy storage device caused by ripple current, and thus extends the life of the energy storage device.

[0105] In one embodiment, such as Figure 19 As shown, the DC-DC converter circuit 310 also includes two additional switching transistors Q3 and Q4, which are connected in series. These two series-connected transistors Q3 and Q4 are also connected in parallel with the two switching transistors Q1 and Q2. One end of the inductor L is also connected to the series connection point of the two additional switching transistors Q3 and Q4. The energy storage device is used to: when the second switch S3 is open, and when the energy storage device is connected to a load or external power supply, control one of the two switching transistors Q1 and Q2 to be normally on, and control the other two switching transistors Q3 and Q4 to be alternately turned on.

[0106] In this embodiment, when the second switch S3 is open, the energy storage device can achieve either boosted or bucked discharge when discharging. Specifically, when the energy storage device controls switch Q3 to be normally on and controls switches Q1 and Q2 to be alternately on, the energy storage device achieves bucked discharge; when the energy storage device controls switch Q1 to be normally on and controls switches Q3 and Q4 to be alternately on, the energy storage device achieves boosted discharge. This ensures the normal operation of the energy storage device's discharge and improves the reliability of the energy storage device's discharge.

[0107] When the energy storage device is charging, it can achieve either boost charging or buck charging. Specifically, when the energy storage device controls switch Q1 to be normally on and controls switches Q3 and Q4 to be alternately on, the energy storage device achieves buck charging; when the energy storage device controls switch Q3 to be normally on and controls switches Q1 and Q2 to be alternately on, the energy storage device achieves boost charging. This ensures the normal charging process of the energy storage device and improves the reliability of the charging process.

[0108] It should be understood that when the second switch S3 is open, the way in which the switching transistors Q1, Q2, Q3, and Q4 are turned on or off when the energy storage device is discharging or charging is not limited to the above-mentioned methods, and may include other implementation methods without restriction.

[0109] In addition, this application also provides an energy storage device, as described above. Figure 2 As shown, the energy storage device includes two battery packs B1 and B2, two switching transistors Q1 and Q2, and an inductor L. Each battery pack includes at least one battery cell. The two battery packs B1 and B2 are connected in series, as are the two switching transistors Q1 and Q2. The two series-connected switching transistors Q1 and Q2 are connected in parallel with the two series-connected battery packs B1 and B2. One end of the inductor L is connected to the series connection point of the two battery packs B1 and B2, and the other end of the inductor L is connected to the series connection point of the two switching transistors Q1 and Q2.

[0110] In this embodiment of the application, the energy storage device is used to: control two switching transistors to alternately conduct multiple times when the capacities of the two battery packs are not equal, so that the battery pack with the larger capacity in each of the P consecutive third cycles charges the other battery pack with the smaller capacity.

[0111] In this embodiment, by controlling the two switching transistors to alternately turn on and off multiple times, the capacity difference between the two battery packs can be reduced. Thus, when the energy storage device discharges or charges, the reduced difference in the capacity of the two battery packs prevents abnormal charging or discharging caused by a large difference in the capacity of the two battery packs, ensuring the normal charging or discharging of the energy storage device. Moreover, it can also prevent charging or discharging failures caused by an excessive difference in the capacity of the two battery packs, thereby extending the lifespan of the energy storage device.

[0112] In one embodiment, taking one battery pack as B1 and the other battery pack as B2 as an example, the energy storage device is used to: when the capacity Q1 of one battery pack B1 is greater than the capacity Q2 of the other battery pack B2, first control the switch Q1 connected in parallel with one battery pack B1 to turn on, and then control the switch Q2 connected in parallel with the other battery pack B2 to turn on.

[0113] When the switching transistor Q1 is turned on, the current in battery pack B1 flows out from the positive terminal, through the switching transistor Q1 and the inductor L, and returns to the negative terminal of battery pack B1, as described above. Figure 3 As shown. During this process, battery pack B1 stores energy in inductor L until the end of the third discharge period of the third cycle. After energy storage in inductor L, control switch Q1 is turned off and control switch Q2 is turned on, so that battery pack B2 can be charged through the freewheeling current of inductor L, and the current flow is as described above. Figure 4 As shown. In this process, inductor L charges battery pack B2 until the end of the third charging period of the third cycle. After several third cycles, some of the charge in battery pack B1 is transferred to battery pack B2, thus reducing the charge in battery pack B1 and increasing the charge in battery pack B2. This reduces the charge difference between battery packs B1 and B2. Therefore, when the energy storage device discharges or charges, the reduced charge difference between the two battery packs prevents abnormal charging or discharging that could be caused by a large charge difference, ensuring normal charging or discharging of the energy storage device. Furthermore, it also prevents charging or discharging failures that could be caused by an excessively large charge difference between the two battery packs, thereby extending the lifespan of the energy storage device.

[0114] In addition, such as Figure 20 As shown, this application also provides a power supply system, which includes a DC-DC converter circuit 132 and at least one energy storage device as described in the above embodiments. When the power supply system includes multiple energy storage devices, the multiple energy storage devices are connected in parallel, and the multiple energy storage devices connected in parallel are connected to the DC-DC converter circuit. The output terminal of the DC-DC converter circuit 132 can be connected to a load. Optionally, the above power supply system may also include a power generation component (not shown in the figure), which can generate electrical energy and store the electrical energy in energy storage devices 131a to 131n to enable energy storage devices 131a to 131n to supply power normally. The power generation component here may include, but is not limited to, solar power generation components, wind power generation components, hydrogen power generation components, or diesel generator power generation components, which can be determined according to the actual application scenario and are not limited here. When energy storage devices 131a to 131n are in a low-temperature environment and are operating normally, the DC / DC converter circuit 132 can convert the DC power provided by energy storage devices 131a to 131n into DC power required by the load, and supply power to the load based on the converted DC power, thereby improving the power supply efficiency in a low-temperature environment.

[0115] In one embodiment, such as Figure 21 As shown, the power supply system also includes a power supply device 133 and a power conversion circuit 134 connected to the power supply device 133. The power conversion circuit 134 and the DC-DC conversion circuit 132 are used to connect the load. (Reference) Figure 13 The power supply device 133 is connected to the input terminal of the power conversion circuit 134, and the output terminal of the power conversion circuit 134 is connected to the load. In a photovoltaic-storage hybrid power supply application scenario, the power supply device 133 may include a photovoltaic array, and the power conversion circuit 134 may be a DC / DC conversion circuit. Here, the photovoltaic array may be composed of multiple photovoltaic modules connected in series and parallel. In a wind-storage hybrid power supply application scenario, the power supply device 133 may include a generator, and the power conversion circuit 134 may be an AC / DC conversion circuit.

[0116] When energy storage devices 131a to 131n are in a low-temperature environment and operating normally, the DC-DC conversion circuit 132 can supply power to the load based on the DC power provided by the energy storage devices 131a to 131n, and the power conversion circuit 134 can convert the DC power provided by the photovoltaic array or the AC power provided by the generator into the DC power required by the load, and supply power to the load based on the converted DC power, thereby further improving the power supply efficiency in a low-temperature environment.

[0117] In specific implementation, further details regarding the operations performed by the energy storage device in the power supply system provided in this application can be found in [reference needed]. Figures 2 to 19 The energy storage device shown and the implementation method of its working principle will not be described in detail here.

[0118] The above description is merely a specific embodiment of this application, but the scope of protection of this application 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 application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An energy storage device, characterized in that, The energy storage device includes two battery packs, two switching transistors, and one inductor. Each battery pack includes at least one battery cell. The two battery packs are connected in series, the two switching transistors are connected in series, the two switching transistors connected in series are connected in parallel with the two battery packs connected in series, one end of the inductor is connected to the series connection point of the two battery packs, and the other end of the inductor is connected to the series connection point of the two switching transistors. The energy storage device is used for: When the temperature of the battery pack is lower than a preset temperature threshold, the two switching transistors are controlled to alternately conduct multiple times, so that in each of the N consecutive first cycles, one group of the battery packs charges the other group of the battery packs, and in each of the M consecutive second cycles, the other group of the battery packs charges one of the battery packs, where N and M are both integers greater than or equal to 1.

2. The energy storage device according to claim 1, characterized in that, The energy storage device is used for: When one of the battery packs is charging the other battery pack, if a preset condition is met, the other battery pack is controlled to charge the one of the battery packs. The preset conditions include at least one of the following: The remaining power of one of the battery packs is less than a preset power, or the discharge depth of one of the battery packs reaches a preset discharge depth, or the charging time of one of the battery packs to the other battery pack reaches a preset time.

3. The energy storage device according to claim 1 or 2, characterized in that, The energy storage device also includes two first capacitors; The two first capacitors are connected in series, and the two first capacitors connected in series are connected in parallel with the two battery packs connected in series. The series connection point of the two first capacitors is connected to the series connection point of the two battery packs, and the series connection point of the two first capacitors is also connected to one end of the inductor.

4. The energy storage device according to claim 3, characterized in that, The energy storage device also includes two first switches, one of which is connected in series with one of the first capacitors, and the other of which is connected in series with the other first capacitor.

5. The energy storage device according to any one of claims 1 to 4, characterized in that, The energy storage device is used for: When the capacity of one group of battery packs is greater than the capacity of the other group of battery packs, or when the discharge voltage of one group of battery packs is greater than the discharge voltage of the other group of battery packs: When the amplitude of the current from one group of battery packs charging the other group of battery packs is equal to the amplitude of the current from the other group of battery packs charging the one group of battery packs, N is controlled to be greater than M; or, When N equals M, the amplitude of the current used to charge one group of battery packs to the other group of battery packs is greater than the amplitude of the current used to charge the other group of battery packs to one group of battery packs.

6. The energy storage device according to any one of claims 1 to 4, characterized in that, The energy storage device is also used for: When the capacity of one group of battery packs is less than the capacity of the other group of battery packs, or when the discharge voltage of one group of battery packs is less than the discharge voltage of the other group of battery packs: When the amplitude of the current from one group of battery packs charging the other group of battery packs is equal to the amplitude of the current from the other group of battery packs charging the one group of battery packs, N is controlled to be less than M; or, When N equals M, the amplitude of the current used to charge one group of battery packs to the other group of battery packs is controlled to be less than the amplitude of the current used to charge the other group of battery packs to one group of battery packs.

7. The energy storage device according to any one of claims 1 to 6, characterized in that, The energy storage device includes a DC-DC converter circuit and a second switch. The DC-DC converter circuit includes two switching transistors and an inductor. One end of the second switch is connected to the other end of the inductor, and the other end of the second switch is connected to the series connection point of the two battery packs. The energy storage device is also used for: When the temperature of the battery pack is lower than the preset temperature threshold, the second switch is controlled to close. When the temperature of the battery pack is greater than or equal to the preset temperature threshold, the second switch is controlled to open.

8. The energy storage device according to claim 7, characterized in that, The DC-DC converter circuit further includes two additional switching transistors connected in series, and these two series-connected transistors are connected in parallel with the two existing switching transistors. One end of the inductor is also connected to the series connection point of the two additional switching transistors. The energy storage device is used for: When the second switch is off, when the energy storage device is connected to a load or an external power source, one of the two switching transistors is controlled to be constantly on while the other two switching transistors are controlled to be alternately turned on.

9. An energy storage device, characterized in that, The energy storage device includes two battery packs, two switching transistors, and one inductor. Each battery pack includes at least one battery cell. The two battery packs are connected in series, the two switching transistors are connected in series, the two switching transistors connected in series are connected in parallel with the two battery packs connected in series, one end of the inductor is connected to the series connection point of the two battery packs, and the other end of the inductor is connected to the series connection point of the two switching transistors. The energy storage device is used for: When the capacities of the two battery packs are not equal, the two switching transistors are controlled to alternately conduct multiple times, so that in each of the P consecutive third cycles, the battery pack with the larger capacity charges the battery pack with the smaller capacity.

10. The energy storage device according to claim 9, characterized in that, The energy storage device is used for: If the capacity of one group of battery packs is greater than that of the other group of battery packs, the switch connected in parallel with one group of battery packs is turned on first, and then the switch connected in parallel with the other group of battery packs is turned on.

11. A power supply system, characterized in that, Includes a DC-DC conversion circuit and at least one energy storage device as described in any one of claims 1 to 6 or 9 to 10. When the power supply system includes multiple energy storage devices, the multiple energy storage devices are connected in parallel, and the multiple energy storage devices connected in parallel are connected to the DC-DC conversion circuit.

12. The power supply system according to claim 11, characterized in that, The power supply system also includes a power supply module and a power conversion circuit connected to the power supply module. The power conversion circuit and the DC-DC conversion circuit are used to connect to the load.

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