A battery pack equalization circuit and energy storage device

Abstract

The embodiment of the application discloses a battery pack equalization circuit and energy storage equipment. The first connection end of the switch control matrix is connected with the series battery pack, the positive and negative poles of the battery to be discharged in the series battery pack and the positive and negative poles of the battery to be charged in the series battery pack are led out by controlling the switch control matrix through the control module, the positive and negative poles of the battery to be discharged are connected to the first connection end of the DCDC module through the input switch module, the positive and negative poles of the battery to be charged are connected to the second connection end of the DCDC module, and the DCDC module is controlled to transfer the electric energy of the battery to be discharged to the battery to be charged, so that the equalization transfer of the electric energy in the series battery pack from the high-energy battery to the low-energy battery is realized, the capacity consistency of the multiple batteries in the series battery pack is achieved, the service life of the multiple series batteries is automatically maintained, the expensive battery pack equalization instrument is not needed to be configured, and the artificial cost problem caused by the maintenance of the inconsistent battery pack by the personnel is reduced.

Description

Technical Field

[0001] This application relates to battery control technology, and more particularly to a battery pack balancing circuit and energy storage device. Background Technology

[0002] With the rapid development of battery technology (such as lithium batteries), batteries are widely used in various industries. Some applications require medium to high voltage, such as 48V, 72V, 84V, or even higher (e.g., 400V), necessitating the connection of multiple batteries in series to form a battery pack. For example, four 12V battery packs connected in series form a 48V battery pack, or six to eight 48V battery packs connected in series form a battery pack exceeding 300V (e.g., home energy storage cabinets).

[0003] Since the usable capacity of the entire battery pack is limited by the worst cell, once a cell is fully charged or discharged first, the entire battery pack must stop charging or discharging, resulting in the inability to fully utilize the capacity of other cells and affecting the overall efficiency of the battery pack. Summary of the Invention

[0004] This application provides a battery pack balancing circuit and energy storage device to solve the technical problem in related technologies where the available capacity of the entire battery pack is limited by the worst cell, the capacity of the battery pack cannot be fully utilized, and the battery pack has low utilization efficiency. The device can perform power balancing processing on the battery pack to improve its utilization efficiency.

[0005] In a first aspect, embodiments of this application provide a battery pack equalization circuit, including a control module, a DC-DC module, a switch control matrix, an input switch module, and an output switch module, wherein: The control module is connected to the control terminal of the DC-DC module, the control terminal of the switch control matrix, the control terminal of the input switch module, and the control terminal of the output switch module; The first connection terminal of the DC-DC module is connected to the first connection terminal of the input switch module, and the second connection terminal of the DC-DC module is connected to the first connection terminal of the output switch module. The first connection terminal of the switch control matrix is ​​used to connect to the series battery pack, and the second connection terminal of the switch control matrix is ​​connected to the second connection terminal of the input switch module and the second connection terminal of the output switch module. The control module is used to control the switch control matrix to lead out the positive and negative terminals of the battery to be discharged and the battery to be charged in the series battery pack, and to control the input switch module to connect the positive and negative terminals of the battery to be discharged to the first connection terminal of the DC-DC module and the positive and negative terminals of the battery to be charged to the second connection terminal of the DC-DC module, and to control the DC-DC module to transfer the electrical energy of the battery to be discharged to the battery to be charged.

[0006] Furthermore, the control module controls the DC-DC module to transfer electrical energy from the battery to be discharged to the battery to be recharged, including: When the number of batteries to be discharged is less than the number of batteries to be charged, the DC-DC module is controlled to switch to boost charging mode to store and boost the electrical energy provided by the batteries to be discharged before transferring it to the batteries to be charged; and / or If the number of batteries to be discharged is greater than the number of batteries to be charged, the DC-DC module is controlled to switch to buck charging mode to transfer the electrical energy provided by the batteries to be discharged to the batteries to be charged after voltage reduction.

[0007] Furthermore, the switch control matrix includes a plurality of first switch units, wherein: The control terminals of multiple first switch units are connected to the control module. The first connection terminal of the first switch unit is used to connect to the positive or negative terminal of one of the batteries in the series battery pack. The positive and negative terminals of each battery in the series battery pack are respectively connected to the first connection terminal of one of the first switch units. The second connection terminal of the first switch unit is connected to the second connection terminal of the input switch module and the second connection terminal of the output switch module.

[0008] Furthermore, the input switch module includes multiple second switch units and a third switch unit, wherein: The control terminal of the second switching unit is connected to the control module, the first connection terminal of each second switching unit is connected to the second connection terminal of a different first switching unit, and the second connection terminal of the second switching unit is connected to the positive terminal interface of the first connection terminal in the DC-DC module. The control terminal of the third switch unit is connected to the control module, the first connection terminal of each third switch unit is connected to the second connection terminal of a different first switch unit, and the second connection terminal of the third switch unit is connected to the negative terminal interface of the first connection terminal in the DC-DC module.

[0009] Furthermore, the output switch module includes multiple fourth switch units and fifth switch units, wherein: The control terminal of the fourth switch unit is connected to the control module, the first connection terminal of each fourth switch unit is connected to the second connection terminal of a different first switch unit, and the second connection terminal of the fourth switch unit is connected to the positive terminal interface of the second connection terminal in the DC-DC module. The control terminal of the fifth switch unit is connected to the control module, the first connection terminal of each fifth switch unit is connected to the second connection terminal of a different first switch unit, and the second connection terminal of the fifth switch unit is connected to the negative terminal interface of the second connection terminal in the DC-DC module.

[0010] Furthermore, the DC-DC module includes a DC-DC controller, an H-bridge circuit, and an energy storage circuit, wherein: The control input terminal of the DC-DC controller is connected to the control module, the control output terminal of the DC-DC controller is connected to the control terminal of the H-bridge circuit, and the energy storage circuit is connected in series between the midpoint of the first arm and the midpoint of the second arm of the H-bridge circuit. The input switch module is connected to the first arm of the H-bridge circuit, and the output switch module is connected to the second arm of the H-bridge circuit.

[0011] Furthermore, in the boost charging state, the DC-DC controller controls the upper transistor of the first bridge arm and the lower transistor of the second bridge arm of the H-bridge circuit to conduct, so that the energy storage circuit can store the electrical energy provided by the energy storage battery, and controls the upper transistor of the first bridge arm and the upper transistor of the second bridge arm of the H-bridge circuit to conduct, so that the energy storage circuit can charge the battery to be charged. In buck charging mode, the DC-DC controller controls the upper transistors of the first and second bridge arms of the H-bridge circuit to conduct, so that the energy storage battery charges the battery to be charged through the energy storage circuit.

[0012] Furthermore, the H-bridge circuit includes a first switch, a second switch, a third switch, and a fourth switch. The control terminals of the first switch, the second switch, the third switch, and the fourth switch are all connected to the control output terminal of the DC-DC controller, wherein: The first connection terminal of the first switching transistor is connected to the positive interface of the output switching module, the second connection terminal of the first switching transistor is connected to the first connection terminal of the third switching transistor and the second connection terminal of the energy storage circuit, and the second connection terminal of the third switching transistor is connected to the negative interface of the output switching module and the second connection terminal of the fourth switching transistor. The first connection terminal of the second switching transistor is connected to the positive interface of the input switch module, the second connection terminal of the second switching transistor is connected to the first connection terminal of the fourth switching transistor and the first connection terminal of the energy storage circuit, and the second connection terminal of the fourth switching transistor is connected to the negative interface of the input switch module.

[0013] Furthermore, the negative terminal of the battery to be discharged is the same as the negative terminal of the battery to be charged.

[0014] In a second aspect, embodiments of this application provide an energy storage device, including a battery pack balancing circuit as described in any of the first aspects.

[0015] This embodiment connects the first connection terminal of the switch control matrix to a series battery pack. The batteries with higher energy in the series battery pack are designated as batteries to be discharged, and the batteries with lower energy are designated as batteries to be recharged. The control module controls the switch control matrix to bring out the positive and negative terminals of the batteries to be discharged and the batteries to be recharged in the series battery pack. The control input switch module connects the positive and negative terminals of the batteries to be discharged to the first connection terminal of the DC-DC module and the positive and negative terminals of the batteries to be recharged to the second connection terminal of the DC-DC module. The DC-DC module then transfers energy from the batteries to the batteries to be recharged, achieving a balanced transfer of energy from high-energy to low-energy batteries within the series battery pack. This ensures capacity consistency among the multiple batteries in the series battery pack, automatically maintains the lifespan of the multi-stage series battery pack, eliminates the need for expensive battery pack balancing equipment, and reduces the labor costs associated with inconsistent battery pack maintenance. Attached Figure Description

[0016] Figure 1 This is a schematic block diagram of a battery pack balancing circuit provided in an embodiment of this application; Figure 2 This is a circuit diagram of a switch control matrix provided in an embodiment of this application; Figure 3 This is a circuit diagram of a DC-DC module provided in an embodiment of this application; Figure 4 This is a circuit diagram of an input switch module and an output switch module provided in an embodiment of this application; Figure 5 This is a schematic diagram of a switching unit circuit provided in an embodiment of this application; Figure 6 This is a schematic diagram of a boost charging method provided in an embodiment of this application; Figure 7 This is a schematic diagram of a step-down charging method provided in an embodiment of this application; Figure 8This is a schematic diagram of an energy storage device provided in this application embodiment.

[0017] Reference numerals: 1. Control module; 2. DC-DC module; 21. DC-DC controller; 22. H-bridge circuit; 221. First switching transistor; 222. Second switching transistor; 223. Third switching transistor; 224. Fourth switching transistor; 23. Energy storage circuit; 3. Switch control matrix; 31. First switching unit; 311. First MOSFET; 322. Second MOSFET; 4. Input switching module; 41. Second switching unit; 42. Third switching unit; 5. Output switching module; 51. Fourth switching unit; 52. Fifth switching unit; 6. Series battery pack. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application will be described in further detail below with reference to the accompanying drawings. It is understood that the specific embodiments described herein are merely for explaining this application and not for limiting it. It should also be noted that, for ease of description, only the parts relevant to this application are shown in the drawings, not all of them. Furthermore, the order of operations can be rearranged. In the description of the embodiments of this application, unless otherwise expressly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0019] The main purpose of connecting batteries in series is to increase the overall voltage, but this brings some disadvantages, such as the "weakest link" effect: the usable capacity of the entire battery pack is limited by the worst cell. Once a cell is fully charged or discharged first, the entire battery pack must stop charging or discharging, resulting in the incomplete utilization of the capacity of other cells; balancing issues: inconsistencies in voltage, capacity, or internal resistance may occur between cells connected in series. These differences will widen over time, requiring additional balancing circuits to dissipate or transfer energy; otherwise, it will accelerate battery aging or even cause danger; and the risk of overcharging or over-discharging individual cells: due to the lack of balancing... Poor battery balancing can lead to several problems. For example, some batteries may be over-voltaged during charging while others are not fully charged, and some may be under-voltaged during discharging. Both overcharging and over-discharging severely damage battery life and can even cause thermal runaway. Furthermore, the increased number of connected batteries means that a single faulty cell or connection point (such as a broken wire or abnormally increased internal resistance) can render the entire battery pack inoperable. The probability of a fault increases linearly with the number of connected cells. Maintenance and replacement are also difficult. When a cell fails, the entire battery pack (or at least all matched cells) usually needs to be replaced; otherwise, mixing old and new cells will exacerbate inconsistencies. Current solutions typically involve using a transformer to isolate and output the appropriate voltage to charge the individual cells requiring balancing. However, this method suffers from insufficient balancing power and low efficiency (increasing power would increase transformer size and power, significantly increasing costs). Alternatively, defective cells can be removed and charged with a charger for maintenance, greatly increasing maintenance costs. Therefore, this application provides a battery pack balancing circuit according to an embodiment of the present application to address these technical problems.

[0020] Figure 1 A schematic block diagram of a battery pack balancing circuit according to an embodiment of this application is provided, with reference to... Figure 1 The battery pack balancing circuit includes a control module 1 (e.g., MCU), a DC-DC module 2, a switch control matrix 3, an input switch module 4, and an output switch module 5.

[0021] The DC-DC module 2 provided in this application can be used to control the bidirectional transmission of electrical energy by controlling the direction of current. The DC-DC module 2 is configured with a control terminal, a first connection terminal, and a second connection terminal. Both the first and second connection terminals are equipped with positive and negative interfaces. The control terminal can control the on / off state of the positive and negative interfaces of the first and second connection terminals, thereby controlling the direction of current between the first and second connection terminals and controlling the DC-DC module 2 to operate in either a boost charging state or a buck charging state. Specifically, when the DC-DC module 2 operates in boost charging state, it boosts the voltage of the power supply connected to the first connection terminal and outputs it from the second connection terminal. When the DC-DC module 2 operates in buck charging state, it bucks the voltage of the power supply connected to the first connection terminal and outputs it from the second connection terminal.

[0022] In this configuration, the first connection terminal of the DC-DC module 2 is connected to the first connection terminal of the input switch module 4, and the second connection terminal of the DC-DC module 2 is connected to the first connection terminal of the output switch module 5. The first connection terminal of the switch control matrix 3 is used to connect the series-connected battery pack 6, and the second connection terminal of the switch control matrix 3 is connected to the second connection terminal of the input switch module 4 and the second connection terminal of the output switch module 5. Optionally, the series-connected battery pack 6 provided in this application includes multiple rechargeable batteries (e.g., lithium batteries) connected in series.

[0023] The control module 1 provided in this application is connected to the control terminals of the DC-DC module 2, the switch control matrix 3, the input switch module 4, and the output switch module 5. For example, the control module 1 is connected to the control terminals of the DC-DC module 2, the switch control matrix 3, the input switch module 4, and the output switch module 5 respectively through an input / output interface (GPIO interface). The control module 1 can send control information to the control terminals of the DC-DC module 2, the switch control matrix 3, the input switch module 4, and the output switch module 5 respectively, thereby controlling the operation of the control module 1, the DC-DC module 2, the switch control matrix 3, the input switch module 4, and the output switch module 5.

[0024] In one embodiment, the batteries to be discharged and the batteries to be charged in the series-connected battery pack 6 can be identified. The battery to be discharged can be understood as a battery that needs to output electrical energy to achieve energy balance, and the battery to be charged can be understood as a battery that needs to absorb electrical energy to achieve energy balance. The battery to be discharged can be one or more batteries connected in series in the series-connected battery pack 6, and the battery to be charged can be one or more batteries connected in series in the series-connected battery pack 6. Optionally, one or more batteries with the highest voltage in the series-connected battery pack 6 can be designated as the battery to be discharged, and one or more batteries with the lowest voltage in the series-connected battery pack 6 can be designated as the battery to be charged. For multiple batteries connected in series in the series-connected battery pack 6, the corresponding positive and negative terminals are the positive and negative terminals of the batteries at both ends. Optionally, the voltage of each battery can be detected by a (built-in or external) battery management module or voltage detection module corresponding to each battery in the series-connected battery pack 6.

[0025] The control module 1 provided in this application can be used to control the switch control matrix 3 to lead out the positive and negative terminals of the battery to be discharged and the battery to be charged in the series battery pack 6, and to control the input switch module 4 to connect the positive and negative terminals of the battery to be discharged to the first connection terminal of the DC-DC module 2, and to connect the positive and negative terminals of the battery to be charged to the second connection terminal of the DC-DC module 2. The control module 1 is also used to control the DC-DC module 2 to input the electrical energy of the battery to be discharged into the DC-DC module 2 through the input switch module 4, and after being boosted or bucked in the DC-DC module 2, it is transmitted to the battery to be charged through the output switch module 5, realizing the transfer of electrical energy from the battery to be discharged to the battery to be charged, so that the electrical energy of the battery to be discharged and the battery to be charged tends to be consistent.

[0026] Optionally, the batteries in the battery to be discharged and the battery to be charged can be in an inclusive relationship, or there may be partially charged batteries. In one embodiment, the DC-DC module 2 can be controlled to switch to a boost charging state or a buck charging state depending on the number of batteries in the battery to be charged and the number of batteries in the battery to be charged. Based on this, the control module 1 provided in this application controls the DC-DC module 2 to transfer electrical energy from the battery to be discharged to the battery to be charged, including: when the number of batteries in the battery to be discharged is less than the number of batteries in the battery to be charged, controlling the DC-DC module 2 to switch to a boost charging state, so as to perform energy storage and boosting processing on the electrical energy provided by the battery to be discharged before transferring it to the battery to be charged; and / or, when the number of batteries in the battery to be discharged is greater than the number of batteries in the battery to be charged, controlling the DC-DC module 2 to switch to a buck charging state, so as to perform buck processing on the electrical energy provided by the battery to be discharged before transferring it to the battery to be charged.

[0027] For example, when there is one battery to be discharged and four batteries to be recharged, the DC-DC module 2 can be controlled to switch to boost charging mode. In boost charging mode, the DC-DC module 2 stores and boosts the energy supplied by the battery to be discharged before transferring it to the battery to be recharged, ensuring that the energy is correctly transferred to the battery to be recharged. When there are two batteries to be discharged and one battery to be recharged, the DC-DC module 2 can be controlled to switch to buck charging mode. In buck charging mode, the DC-DC module 2 steps down the energy supplied by the battery to be discharged before transferring it to the battery to be recharged, ensuring that the energy is correctly transferred to the battery to be recharged.

[0028] In one possible embodiment, the negative terminal of the battery to be discharged is the same as the negative terminal of the battery to be charged. That is, the battery from which the negative terminal is drawn in the battery to be discharged is the same battery as the battery from which the negative terminal is drawn in the battery to be charged. Both the negative terminals of the battery to be discharged and the negative terminals of the battery to be charged are connected to the common negative terminal of the DC-DC module 2. This method can be applied to DC-DC conversion scenarios with larger currents without the need for transformer isolation. In addition, the step-up and step-down range of this DC-DC can be flexibly adjusted according to the actual battery voltage, and it has advantages in terms of size, cost, and conversion efficiency. It also effectively solves the problem of inconvenient voltage adjustment in traditional isolation transformer DC-DC. In one embodiment, a current detection and SOC capacity calculation circuit for the series battery pack 6 can also be set. The control module 1 is connected to a Bluetooth module and CAN, RS485 communication and LCD screen to display relevant setting parameters and application data on the APP, LCD and PC, realizing more convenient human-machine communication and control.

[0029] In one embodiment, such as Figure 2 As shown in the circuit diagram of a switch control matrix provided in this application, the switch control matrix 3 includes a plurality of first switch units 31, wherein the control terminals of the plurality of first switch units 31 are connected to the control module 1. The control module 1 can send control information to the control terminals of different first switch units 31 respectively to control the on / off of the first connection terminal and the second connection terminal of each first switch unit 31, thereby controlling the conduction and off of each first switch unit 31.

[0030] Furthermore, the first connection terminal of the first switching unit 31 is used to connect to the positive or negative terminal of one of the batteries in the series battery pack 6. The positive and negative terminals of each battery in the series battery pack 6 are respectively connected to the first connection terminal of one of the first switching units 31. The second connection terminal of the first switching unit 31 is connected to the second connection terminal of the input switch module 4 and the second connection terminal of the output switch module 5. The first connection terminal of one first switching unit 31 is connected to the positive terminal of the battery at one end of the series battery pack 6, or the negative terminal of the battery at the other end, or to the positive and negative connection point of an adjacent battery.

[0031] The number of first switch units 31 can be the number of batteries in the series-connected battery pack 6 plus one, so that the positive and negative terminals of each battery can be connected to the first connection terminal of a first switch unit 31 respectively, and two adjacent batteries can be connected to the first connection terminal of the same first switch unit 31. By combining different combinations of turning on and off the first switch units 31, the positive and negative terminals of different batteries or series-connected battery combinations can be brought out. For example, turning on the first switch unit 31 connected to the positive and negative terminals of the battery or series-connected battery combination that needs to be brought out, and turning off other first switch units 31, can realize the bringing out of the positive and negative terminals of the corresponding battery or series-connected battery combination.

[0032] The diagram illustrates an example of a series-connected battery pack 6 with four batteries and five first switching units 31. The four batteries are designated BATTERY1, BATTERY2, BATTERY3, and BATTERY4. B1 and B0 are the positive and negative terminals of battery BATTERY1, B2 and B1 are the positive and negative terminals of battery BATTERY2, B3 and B2 are the positive and negative terminals of battery BATTERY3, and B4 and B3 are the positive and negative terminals of battery BATTERY4. The first connection terminals of the five first switching units 31 are connected to B0, B1, B2, B3, and B4, respectively. For example, when it is necessary to connect the positive and negative terminals of battery BATTERY1, the first switching unit 31 connected to B0 and B1 can be turned on; when it is necessary to connect the positive and negative terminals of batteries BATTERY1 and BATTERY2, the first switching unit 31 connected to B0 and B2 can be turned on. This application uses multiple first switch units 31 to form a switch control matrix 3, and flexibly leads out the positive and negative terminals of the battery to be discharged and the battery to be charged in the series battery pack 6 by switching the multiple first switch units 31 on and off, so as to achieve flexible processing of battery pack balance.

[0033] In one embodiment, such as Figure 3 A circuit diagram of a DC-DC module is provided. The DC-DC module 2 provided in this application includes a DC-DC controller 21 (e.g., a DC-DC control chip), an H-bridge circuit 22, and an energy storage circuit 23. The control input terminal of the DC-DC controller 21 is connected to the control module 1, and the control output terminal of the DC-DC controller 21 is connected to the control terminal of the H-bridge circuit 22. The energy storage circuit 23 is connected in series between the midpoints of the first and second arms of the H-bridge circuit 22. The input switch module 4 is connected to the first arm of the H-bridge circuit 22, and the output switch module 5 is connected to the second arm of the H-bridge circuit 22.

[0034] In this design, the first and second arms of the H-bridge circuit 22 can be a left arm (connected to the input switch module 4) and a right arm (connected to the output switch module 5). The midpoint of the first arm is the connection point between the upper and lower transistors in the first arm, and the midpoint of the second arm is the connection point between the upper and lower transistors in the second arm. The ends of the lower transistors in the first and second arms of the H-bridge circuit 22 are connected, while the ends of the upper transistors in the first and second arms are not connected. Optionally, the energy storage circuit 23 may include an inductor, with the two ends of the inductor corresponding to the first and second connection terminals of the energy storage circuit 23, respectively.

[0035] The energy storage circuit 23 provided in this application can be used to store the electrical energy provided by the battery to be discharged, and to discharge the battery to be charged. It can also be used to limit the current and reduce the voltage of the electrical energy flowing to the battery to be charged. The control module 1 can send corresponding control signals to the control input terminal of the DCDC controller 21, so that the DCDC controller 21 controls the on and off of each switch in the H-bridge circuit 22 through the control output terminal, so that the bidirectional DCDC module 2 can switch between boost charging state and buck charging state, realizing flexible control of battery testing.

[0036] In one embodiment, the DC-DC controller 21 can control the first upper arm transistor and the second lower arm transistor of the H-bridge circuit 22 to conduct (and the first lower arm transistor and the second upper arm transistor to turn off) during boost charging, so that the energy storage circuit 23 can store the electrical energy provided by the battery to be discharged, and control the first upper arm transistor and the second upper arm transistor of the H-bridge circuit 22 to conduct (and the first lower arm transistor and the second lower arm transistor to turn off) so that the energy storage circuit 23 can charge the battery to be charged. Specifically, by alternately controlling the conduction of the upper transistor of the first bridge arm and the lower transistor of the second bridge arm of the H-bridge circuit 22, and controlling the conduction of the upper transistor of the first bridge arm and the lower transistor of the second bridge arm of the H-bridge circuit 22, the battery to be discharged charges the energy storage circuit 23 when the upper transistor of the first bridge arm and the lower transistor of the second bridge arm of the H-bridge circuit 22 are conducting. When the upper transistor of the first bridge arm and the lower transistor of the second bridge arm of the H-bridge circuit 22 are conducting, the battery to be discharged and the energy storage circuit 23 charge the battery to be charged. At this time, the voltage charged to the battery to be charged is higher than the voltage of the battery to be discharged. By controlling the conduction of the upper transistor of the first bridge arm and the lower transistor of the second bridge arm, and the duration and time ratio of the conduction of the upper transistor of the first bridge arm and the lower transistor of the second bridge arm, the voltage charged to the battery to be charged can be controlled.

[0037] In one embodiment, the DC-DC controller 21 can also be controlled to turn on the upper transistors of the first and second arms of the H-bridge circuit 22 (while turning off the lower transistors of the first and second arms) during buck charging, so that the battery to be discharged charges the battery to be charged through the energy storage circuit 23. Furthermore, the current-limiting characteristics of the energy storage circuit 23 achieve a buck effect on the energy supplied to the battery to be discharged, reducing the charging voltage of the battery to be charged. The charging voltage to the battery can be controlled by alternately controlling the conduction duration and time ratio of the upper transistors of the first and second arms of the H-bridge circuit 22.

[0038] In one possible embodiment, the H-bridge circuit 22 provided in this application may include a first switch 221, a second switch 222, a third switch 223, and a fourth switch 224 (corresponding to the upper switch of the second bridge arm, the upper switch of the first bridge arm, the lower switch of the second bridge arm, and the lower switch of the first bridge arm, respectively). The control terminals of the first switch 221, the second switch 222, the third switch 223, and the fourth switch 224 are all connected to the control output terminal of the DC-DC controller 21. Optionally, the (first to fourth) switches provided in this application may be MOS transistors (e.g., NMOS transistors), with the control terminal of the switch being the gate, the first connection terminal being the drain, and the second connection terminal being the source.

[0039] Specifically, the first terminal of the first switching transistor 221 is connected to the positive interface of the output switching module 5; the second terminal of the first switching transistor 221 is connected to the first terminal of the third switching transistor 223 and the second terminal of the energy storage circuit 23; the second terminal of the third switching transistor 223 is connected to the negative interface of the output switching module 5 and the second terminal of the fourth switching transistor 224. The first terminal of the second switching transistor 222 is connected to the positive interface of the input switching module 4; the second terminal of the second switching transistor 222 is connected to the first terminal of the fourth switching transistor 224 and the first terminal of the energy storage circuit 23; and the second terminal of the fourth switching transistor 224 is connected to the negative interface of the input switching module 4.

[0040] In the boost charging state, the second switch 222 and the third switch 223 are turned on, while the fourth switch 224 and the first switch 221 are turned off. This allows the energy storage circuit 23 to store the electrical energy supplied by the battery to be discharged. The second switch 222 and the first switch 221 are turned on, while the fourth switch 224 and the third switch 223 are turned off. This cycle repeats, allowing the energy storage circuit 23 to repeatedly charge and charge the battery to be charged, thus achieving boost charging of the battery to be charged. In the buck charging state, the first switch 221 and the second switch 222 are turned on, while the third switch 223 and the fourth switch 224 are turned off. This allows the battery to be discharged to charge the battery to be charged via the energy storage circuit 23, and the energy storage circuit 23 limits the charging voltage, thus achieving buck charging of the battery to be charged.

[0041] In one embodiment, control module 1 can connect to DC-DC controller 21 via the I2C communication protocol (e.g., the SCL2 and SDA2 pins of control module 1 are connected to the SCL and SDA pins of DC-DC controller 21), enabling communication between control module 1 and DC-DC controller 21. Control module 1 can set the control parameters of DC-DC controller 21 through the I2C communication interface. DC-DC controller 21 controls the switching of four transistors according to the control parameters to control the output current and voltage. The DIR pin of control module 1 is also connected to the DIR pin (i.e., the control input terminal) of DC-DC controller 21. When the battery to be discharged needs to charge the battery to be recharged, the DIR pin of control module 1 is set to a low level (LOW), controlling DC-DC controller 21 to control the switching of the four transistors to achieve the purpose of charging the battery to be recharged.

[0042] For example, the DC-DC controller 21 can be controlled to turn on the upper transistor of the first bridge arm and the lower transistor of the second bridge arm of the H-bridge circuit 22 (and turn off the lower transistor of the first bridge arm and the upper transistor of the second bridge arm) when the DC-DC controller 21 is in boost charging mode, so that the energy storage circuit 23 can store the electrical energy provided by the battery to be discharged, and control the upper transistor of the first bridge arm and the upper transistor of the second bridge arm of the H-bridge circuit 22 to turn on (and turn off the lower transistor of the first bridge arm and the lower transistor of the second bridge arm) so that the energy storage circuit 23 can charge the battery to be charged. Specifically, by alternately controlling the conduction of the upper transistor of the first bridge arm and the lower transistor of the second bridge arm of the H-bridge circuit 22, and controlling the conduction of the upper transistor of the first bridge arm and the lower transistor of the second bridge arm of the H-bridge circuit 22, the battery to be discharged charges the energy storage circuit 23 when the upper transistor of the first bridge arm and the lower transistor of the second bridge arm of the H-bridge circuit 22 are conducting. When the upper transistor of the first bridge arm and the lower transistor of the second bridge arm of the H-bridge circuit 22 are conducting, the battery to be discharged and the energy storage circuit 23 charge the battery to be charged. At this time, the voltage charged to the battery to be charged is higher than the voltage of the battery to be discharged. By controlling the conduction of the upper transistor of the first bridge arm and the lower transistor of the second bridge arm, and the duration and time ratio of the conduction of the upper transistor of the first bridge arm and the lower transistor of the second bridge arm, the voltage charged to the battery to be charged can be controlled.

[0043] In one embodiment, such as Figure 4The circuit diagrams provided for an input switch module and an output switch module are shown. The input switch module 4 provided in this application includes multiple second switch units 41 and multiple third switch units 42, and the output switch module 5 includes multiple fourth switch units 51 and multiple fifth switch units 52. The diagram illustrates the circuits of one input switch module 4 (which is connected to the first switch unit 31 whose positive and negative terminals corresponding to battery BATTERY1 are connected to B1 and B0) and one output switch module 5 (which is connected to the first switch unit 31 whose positive and negative terminals corresponding to batteries BATTERY1-BATTERY4 are connected to B4 and B0). The circuits of the remaining input switch modules 4 and output switch modules 5 can be referenced. Figure 4 This application will not elaborate further.

[0044] In this configuration, the control terminal of the second switch unit 41 is connected to the control module 1, and the first connection terminal of each second switch unit 41 is connected to the second connection terminal of a different first switch unit 31. The second connection terminal of the second switch unit 41 is connected to the positive terminal interface of the first connection terminal in the DC-DC module 2. Optionally, the number of second switch units 41 can be the same as the number of batteries in the series battery pack 6, and the first connection terminal of each second switch unit 41 is connected to the second connection terminal of one of the first switch units 31 connected to the positive terminal of a battery in the series battery pack 6. Thus, by controlling the on / off state of the second switch unit 41, the positive terminal of the battery introduced into the positive terminal interface of the first connection terminal in the DC-DC module 2 can be selected. For example, the second switch unit 41 corresponding to the first switch unit 31 connected to the positive terminal of the battery to be charged can be turned on, thereby bringing out the positive terminal of the battery to be charged.

[0045] The control terminal of the third switch unit 42 is connected to the control module 1. The first connection terminal of each third switch unit 42 is connected to the second connection terminal of a different first switch unit 31. The second connection terminal of the third switch unit 42 is connected to the negative terminal interface of the first connection terminal in the DCDC module 2. Optionally, the number of third switch units 42 can be the same as the number of batteries in the series battery pack 6, and the first connection terminal of each third switch unit 42 is connected to the second connection terminal of one of the first switch units 31 connected to the negative terminal of a battery in the series battery pack 6. Thus, by controlling the on / off state of the third switch unit 42, the negative terminal of the battery introduced into the negative terminal interface of the first connection terminal in the DCDC module 2 can be selected. For example, the third switch unit 42 corresponding to the first switch unit 31 connected to the negative terminal of the battery to be charged can be turned on, thereby realizing the negative terminal of the battery to be charged is brought out. This application realizes the positive and negative terminals of the battery to be charged are brought out through multiple second switch units 41 and third switch units 42, accurately connecting the battery to be discharged for discharge, and achieving precise control of battery pack balance.

[0046] In one embodiment, the control terminal of the fourth switch unit 51 is connected to the control module 1, the first connection terminal of each fourth switch unit 51 is connected to the second connection terminal of a different first switch unit 31, and the second connection terminal of the fourth switch unit 51 is connected to the positive terminal interface of the second connection terminal in the DC-DC module 2. Optionally, the number of fourth switch units 51 can be the same as the number of batteries in the series battery pack 6, and the first connection terminal of each fourth switch unit 51 is connected to the second connection terminal of one of the first switch units 31 connected to the positive terminal of a battery in the series battery pack 6. Thus, by controlling the on / off state of the fourth switch unit 51, the positive terminal of the battery introduced into the positive terminal interface of the second connection terminal in the DC-DC module 2 can be selected. For example, the fourth switch unit 51 corresponding to the first switch unit 31 connected to the positive terminal of the battery to be charged can be turned on to realize the positive terminal of the battery to be charged being brought out.

[0047] The control terminal of the fifth switch unit 52 is connected to the control module 1. The first connection terminal of each fifth switch unit 52 is connected to the second connection terminal of a different first switch unit 31. The second connection terminal of the fifth switch unit 52 is connected to the negative terminal interface of the second connection terminal in the DCDC module 2. Optionally, the number of fifth switch units 52 can be the same as the number of batteries in the series battery pack 6, and the first connection terminal of each fifth switch unit 52 is connected to the second connection terminal of one of the first switch units 31 connected to the negative terminal of a battery in the series battery pack 6. Thus, by controlling the on / off state of the fifth switch unit 52, the negative terminal of the battery introduced into the negative terminal interface of the first connection terminal in the DCDC module 2 can be selected. For example, the fifth switch unit 52 corresponding to the first switch unit 31 connected to the negative terminal of the battery to be charged can be turned on, thereby realizing the negative terminal of the battery to be charged. This application realizes the positive and negative terminals of the battery to be charged through multiple fourth switch units 51 and fifth switch units 52, accurately connecting the battery to be charged for charging, and achieving precise control of battery pack balance.

[0048] In one embodiment, the switching unit provided in this application (including the first to fifth switching units 52) can be a MOSFET (e.g., an NMOS transistor). The control terminal of the MOSFET is the gate, the first connection terminal is the drain, and the second connection terminal is the source. The switching unit can be turned on and off by sending high and low level control signals to the gate of the MOSFET. The switching unit can be composed of two MOSFETs (e.g., NMOS transistors), such as... Figure 5A schematic diagram of a switching unit circuit is provided, wherein two MOSFETs are a first MOSFET 311 and a second MOSFET 322. The gate of the first MOSFET 311 and the gate of the second MOSFET 322 are connected and connected to the cathode of a diode. The anode of the diode serves as the control terminal of the switching unit. The source of the first MOSFET 311 and the source of the second MOSFET 322 are connected. The drain of the first MOSFET 311 serves as the first connection terminal of the switching unit, and the drain of the second MOSFET 322 serves as the second connection terminal of the switching unit. The source of the first MOSFET 311 is also connected to the collector of a PNP transistor. The emitter of the PNP transistor is connected to the cathode of the aforementioned diode, and the base is connected to the anode of the diode. A resistor is also connected between the collector and emitter of the PNP transistor. The switching unit can be controlled by sending high or low level control signals to the gate of the MOSFETs. For example, when a high-level control signal is sent to the switching unit, the first MOSFET 311 and the second MOSFET 322 are turned on, and the corresponding switching unit is turned on. When a low-level control signal is sent to the switching unit, the first MOSFET 311 and the second MOSFET 322 are turned off, and the corresponding switching unit is turned off.

[0049] like Figure 6The provided schematic diagram illustrates a boost charging method. Assuming four batteries (BATTERY1 to BATTERY4) are connected in series to form a series battery pack 6 with higher voltages of 48V, 60V, and 84V for various industry applications, in actual use, various factors can cause inconsistencies in the charge and voltage of individual batteries compared to the others. This leads to low efficiency and lifespan of the entire battery pack, sometimes requiring manual maintenance or battery replacement. The battery pack balancing circuit provided in this application actively balances the charge and voltage between different batteries, effectively improving the overall efficiency and extending the lifespan of the battery pack, eliminating the need for frequent battery maintenance or replacement. Assuming that the voltage and charge of battery BATTERY1 are higher than those of batteries BATTERY2 to BATTERY4, the charge from battery BATTERY1 needs to be transferred to batteries BATTERY2 to BATTERY4. In other words, battery BATTERY1 is the battery to be discharged, and battery pack BATTERY1 to BATTERY4 are the batteries to be recharged. Based on this, the first switch unit 31 connected to B0 and B1 can be turned on by the switch control matrix 3, thereby introducing the negative and positive terminals of the battery BATTERY1. In the figure, B0_INPUT is the negative terminal of the battery BATTERY1, and B1_INPUT is the positive terminal of the battery BATTERY1. The positive and negative terminals of the battery BATTERY1 are connected to the first connection terminal of the DC-DC module 2 through the input switch module 4. The figure only shows the second switch unit 41 and the third switch unit 42 that introduce the battery BATTERY1 in the input switch module 4. The first switch unit 31 connected to B4 is turned on by the switch control matrix 3, thereby introducing the positive terminal of the battery packs BATTERY1~BATTERY4. The negative terminal of the battery packs BATTERY1~BATTERY4 has been brought out through B0_INPUT. In the figure, B0_INPUT is the negative terminal of the battery packs BATTERY1~BATTERY4, and B4_INPUT is the positive terminal of the battery packs BATTERY1~BATTERY4. The positive and negative terminals of the battery packs BATTERY1~BATTERY4 are connected to the second connection terminal of the DC-DC module 2 through the output switch module 5. The figure only shows the fourth switch unit 51 and the fifth switch unit 52 in the output switch module 5 that introduce the battery packs BATTERY1~BATTERY4.

[0050] Furthermore, the DC-DC module 2 is controlled to operate in a boost charging state to charge the positive terminal of battery B4. It needs to be explained that although the voltage energy of a single battery BATTERY1 is higher than that of BATTERY2 through BATTERY4, the voltage of a single battery BATTERY1 is lower than the total voltage of the battery pack BATTERY1 through BATTERY4 connected in series. According to the law of conservation of energy P=UI, the current I(input) from battery BATTERY1 to DC-DC module 2 is greater than the current I(output) from DC-DC module 2. This causes the output current I(output) to flow into batteries BATTERY2 through BATTERY4, and the current flowing out of battery BATTERY1 is I(input) - I(output). This achieves the transfer of energy from battery BATTERY1 to the other three batteries, achieving a uniform voltage and energy level after a certain charging time. Because the four batteries are connected in series, there are 2 to the power of N possible combinations, resulting in 16 different combinations of battery pack voltage and energy.

[0051] like Figure 7As shown in the provided step-down charging diagram, assuming that the voltage of battery BATTERY1 is 45V, the voltage of battery BATTERY2 is 47V, the voltage of battery BATTERY3 is 42V, and the voltage of battery BATTERY4 is 48V, battery BATTERY3 has the lowest voltage and the highest voltage and capacity. It is necessary to transfer the capacity of battery BATTERY4 to battery BATTERY3. The series-connected batteries BATTERY3 and BATTERY4 can be used as batteries to be discharged, and battery BATTERY3 is the battery to be charged. Based on this, the first switch unit 31 connected to B2 and B4 can be turned on by the switch control matrix 3, thereby introducing the negative and positive terminals of batteries BATTERY3~4. In the figure, B2_INPUT is the negative terminal of batteries BATTERY3~4, and B4_INPUT is the positive terminal of batteries BATTERY3~4. The positive and negative terminals of batteries BATTERY3~4 are connected to the first connection terminal of DC-DC module 2 through the input switch module 4. The figure only shows the second switch unit 41 and the third switch unit 42 that introduce batteries BATTERY3~4 in the input switch module 4. The first switching unit 31, connected to B3, is activated by the switch control matrix 3, thereby introducing the positive terminal of battery BATTERY3. The negative terminal of battery BATTERY3 is led out through B2_INPUT. In the figure, B2_INPUT is the negative terminal of battery BATTERY3, and B3_INPUT is the positive terminal of battery BATTERY3. The positive and negative terminals of battery BATTERY3 are connected to the second connection terminal of DC-DC module 2 through output switch module 5, respectively. The figure only shows the fourth switching unit 51 and the fifth switching unit 52 in output switch module 5 that introduce battery BATTERY3. Furthermore, DC-DC module 2 is controlled to operate in a step-down charging state to charge the positive terminal of B4.

[0052] At this point, the total voltage of batteries BATTERY3~4 is higher than the voltage of battery BATTERY3. According to the law of conservation of energy P=UI, the current input from batteries BATTERY3~4 to DC-DC module 2 is less than the current output I(output) of DC-DC module 2. This causes battery BATTERY4 to lose I(input), resulting in a decrease in energy voltage. Meanwhile, the current flowing into battery BATTERY3 is I(output) - I(input), leading to an increase in energy voltage. This achieves energy transfer between the two adjacent batteries BATTERY3 and BATTERY4, achieving voltage and capacity consistency after a certain charging time. Subsequently, the voltage and energy of batteries BATTERY1~BATTERY4 can be reassessed to redefine the input and output terminals of DC-DC module 2 for boost or buck operation, and the energy transfer balancing function between voltage and capacity can be performed again, ultimately achieving voltage and capacity consistency across the four battery packs.

[0053] As described above, by connecting the first connection terminal of the switch control matrix 3 to the series battery pack 6, the batteries with higher energy in the series battery pack 6 are designated as batteries to be discharged, and the batteries with lower energy in the series battery pack 6 are designated as batteries to be charged. The control module 1 controls the switch control matrix 3 to bring out the positive and negative terminals of the batteries to be discharged and the batteries to be charged in the series battery pack 6. The control input switch module 4 connects the positive and negative terminals of the batteries to be discharged to the first connection terminal of the DC-DC module 2 and the positive and negative terminals of the batteries to be charged to the second connection terminal of the DC-DC module 2. The DC-DC module 2 is then controlled to transfer the energy from the batteries to the batteries to be charged. This achieves a balanced transfer of energy from high-energy batteries to low-energy batteries in the series battery pack 6, ensuring the capacity consistency of multiple batteries in the series battery pack 6. It automatically maintains the lifespan of the multi-stage series batteries, eliminating the need for expensive battery pack balancing equipment and reducing the labor costs associated with inconsistent battery pack maintenance.

[0054] Figure 8 A schematic block diagram of an energy storage device according to an embodiment of this application is provided. (Reference) Figure 8 The energy storage device is characterized by including a battery pack balancing circuit as provided in any of the above embodiments. The battery pack balancing circuit provided in this application can refer to the battery pack balancing circuit provided in any of the above embodiments and has the corresponding technical effects; further details are omitted here.

[0055] As described above, by connecting the first connection terminal of the switch control matrix to the series battery pack, the batteries with higher energy in the series battery pack are designated as batteries to be discharged, and the batteries with lower energy in the series battery pack are designated as batteries to be charged. The control module controls the switch control matrix to bring out the positive and negative terminals of the batteries to be discharged and the batteries to be charged in the series battery pack. The control input switch module connects the positive and negative terminals of the batteries to be discharged to the first connection terminal of the DC-DC module and the positive and negative terminals of the batteries to be charged to the second connection terminal of the DC-DC module. The DC-DC module then transfers energy from the batteries to the batteries to be charged, achieving a balanced transfer of energy from high-energy batteries to low-energy batteries in the series battery pack. This ensures the consistency of capacity among multiple batteries in the series battery pack, automatically maintains the lifespan of multi-stage series batteries, eliminates the need for expensive battery pack balancing equipment, and reduces the labor costs associated with inconsistent battery pack maintenance.

[0056] The above description is merely a preferred embodiment and the technical principles employed in this application. This application is not limited to the specific embodiments provided herein, and various obvious changes, readjustments, and substitutions that can be made by those skilled in the art will not depart from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of this application, the scope of which is determined by the scope of the claims.

Claims

1. A battery pack balancing circuit, characterized in that, It includes a control module, a DC-DC converter module, a switch control matrix, an input switch module, and an output switch module, wherein: The control module is connected to the control terminal of the DC-DC module, the control terminal of the switch control matrix, the control terminal of the input switch module, and the control terminal of the output switch module; The first connection terminal of the DC-DC module is connected to the first connection terminal of the input switch module, and the second connection terminal of the DC-DC module is connected to the first connection terminal of the output switch module. The first connection terminal of the switch control matrix is ​​used to connect to the series battery pack, and the second connection terminal of the switch control matrix is ​​connected to the second connection terminal of the input switch module and the second connection terminal of the output switch module. The control module is used to control the switch control matrix to lead out the positive and negative terminals of the battery to be discharged and the battery to be charged in the series battery pack, and to control the input switch module to connect the positive and negative terminals of the battery to be discharged to the first connection terminal of the DC-DC module and the positive and negative terminals of the battery to be charged to the second connection terminal of the DC-DC module, and to control the DC-DC module to transfer the electrical energy of the battery to be discharged to the battery to be charged.

2. The battery pack balancing circuit according to claim 1, characterized in that, The control module controls the DC-DC module to transfer electrical energy from the battery to be discharged to the battery to be recharged, including: When the number of batteries to be discharged is less than the number of batteries to be charged, the DC-DC module is controlled to switch to boost charging mode to store and boost the electrical energy provided by the batteries to be discharged before transferring it to the batteries to be charged; and / or If the number of batteries to be discharged is greater than the number of batteries to be charged, the DC-DC module is controlled to switch to buck charging mode to transfer the electrical energy provided by the batteries to be discharged to the batteries to be charged after voltage reduction.

3. The battery pack balancing circuit according to claim 1, characterized in that, The switch control matrix includes multiple first switch units, wherein: The control terminals of multiple first switch units are connected to the control module. The first connection terminal of the first switch unit is used to connect to the positive or negative terminal of one of the batteries in the series battery pack. The positive and negative terminals of each battery in the series battery pack are respectively connected to the first connection terminal of one of the first switch units. The second connection terminal of the first switch unit is connected to the second connection terminal of the input switch module and the second connection terminal of the output switch module.

4. The battery pack balancing circuit according to claim 3, characterized in that, The input switch module includes multiple second switch units and a third switch unit, wherein: The control terminal of the second switching unit is connected to the control module, the first connection terminal of each second switching unit is connected to the second connection terminal of a different first switching unit, and the second connection terminal of the second switching unit is connected to the positive terminal interface of the first connection terminal in the DC-DC module. The control terminal of the third switch unit is connected to the control module, the first connection terminal of each third switch unit is connected to the second connection terminal of a different first switch unit, and the second connection terminal of the third switch unit is connected to the negative terminal interface of the first connection terminal in the DC-DC module.

5. The battery pack balancing circuit according to claim 3, characterized in that, The output switch module includes multiple fourth switch units and fifth switch units, wherein: The control terminal of the fourth switch unit is connected to the control module, the first connection terminal of each fourth switch unit is connected to the second connection terminal of a different first switch unit, and the second connection terminal of the fourth switch unit is connected to the positive terminal interface of the second connection terminal in the DC-DC module. The control terminal of the fifth switch unit is connected to the control module, the first connection terminal of each fifth switch unit is connected to the second connection terminal of a different first switch unit, and the second connection terminal of the fifth switch unit is connected to the negative terminal interface of the second connection terminal in the DC-DC module.

6. The battery pack balancing circuit according to claim 1, characterized in that, The DC-DC module includes a DC-DC controller, an H-bridge circuit, and an energy storage circuit, wherein: The control input terminal of the DC-DC controller is connected to the control module, the control output terminal of the DC-DC controller is connected to the control terminal of the H-bridge circuit, and the energy storage circuit is connected in series between the midpoint of the first arm and the midpoint of the second arm of the H-bridge circuit. The input switch module is connected to the first arm of the H-bridge circuit, and the output switch module is connected to the second arm of the H-bridge circuit.

7. The battery pack balancing circuit according to claim 6, characterized in that, In boost charging mode, the DC-DC controller controls the upper transistor of the first bridge arm and the lower transistor of the second bridge arm of the H-bridge circuit to conduct, so that the energy storage circuit can store the electrical energy provided by the energy storage battery, and controls the upper transistor of the first bridge arm and the upper transistor of the second bridge arm of the H-bridge circuit to conduct, so that the energy storage circuit can charge the battery to be charged. In buck charging mode, the DC-DC controller controls the upper transistors of the first and second bridge arms of the H-bridge circuit to conduct, so that the energy storage battery charges the battery to be charged through the energy storage circuit.

8. The battery pack balancing circuit according to claim 6, characterized in that, The H-bridge circuit includes a first switch, a second switch, a third switch, and a fourth switch. The control terminals of the first switch, the second switch, the third switch, and the fourth switch are all connected to the control output terminal of the DC-DC controller. The first connection terminal of the first switching transistor is connected to the positive interface of the output switching module, the second connection terminal of the first switching transistor is connected to the first connection terminal of the third switching transistor and the second connection terminal of the energy storage circuit, and the second connection terminal of the third switching transistor is connected to the negative interface of the output switching module and the second connection terminal of the fourth switching transistor. The first connection terminal of the second switching transistor is connected to the positive interface of the input switch module, the second connection terminal of the second switching transistor is connected to the first connection terminal of the fourth switching transistor and the first connection terminal of the energy storage circuit, and the second connection terminal of the fourth switching transistor is connected to the negative interface of the input switch module.

9. The battery pack balancing circuit according to claim 1, characterized in that, The negative terminal of the battery to be discharged is the same as the negative terminal of the battery to be charged.

10. An energy storage device, characterized in that, Includes the battery pack equalization circuit as described in any one of claims 1-9.

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