A battery branch off-line equalization device and method

Abstract

The application discloses a kind of battery branch offline equalization device and method, it is related to power battery maintenance technical field, including high-voltage bus, multiple high-voltage interface groups, branch switch unit, energy transfer unit, switching switch unit and control unit.Control unit is configured as: control all the corresponding branch contactor of healthy branch closure, make it parallel in high-voltage bus to form reference voltage;Control switching switch unit connects the high-voltage interface group corresponding to the fault branch to energy transfer unit, and control the corresponding branch contactor of fault branch is disconnected;If the absolute value of the difference between the voltage of fault branch and reference voltage is not less than preset safety threshold, control energy transfer unit to carry out energy transfer, until the absolute value of difference is less than preset safety threshold;Control the corresponding branch contactor of fault branch closure, make it parallel in high-voltage bus.The application solves the problems that the existing vehicle-mounted multi-branch power battery system is high in single vehicle cost, prone to failure in vibration environment and high in maintenance complexity.

Description

Technical Field

[0001] This invention relates to the field of power battery maintenance technology, and in particular to a battery branch offline balancing device and method. Background Technology

[0002] With the rapid development of new energy logistics vehicles and electric trucks, multi-branch parallel power battery systems are widely used due to their high capacity and high reliability. In actual operation, a branch within the battery system may require individual replacement or maintenance due to failure or aging. When a new battery branch is connected to the system, the voltage difference between the new branch and the remaining healthy online branches can cause a huge circulating current surge, potentially damaging individual battery cells and impacting high-voltage contactors and bus capacitors, thus affecting the safety and lifespan of the entire battery system.

[0003] In existing technologies, an on-board active balancing scheme is typically used to address the voltage inconsistency issue when connecting branch circuits. This scheme involves configuring complete high-voltage balancing hardware on each vehicle, integrating it into the vehicle's high-voltage distribution box or battery pack, and centrally controlling it under the vehicle's battery management system (BMS). During maintenance, the on-board hardware controls the energy transfer between the faulty branch and the healthy branch, and the main circuit is closed only after the voltage is equalized.

[0004] However, the above-mentioned vehicle-mounted solution has the following drawbacks: First, the vehicle-mounted solution requires high-voltage equalization hardware to be configured on each vehicle, resulting in high cost per vehicle and increasing the initial purchase cost of the vehicle; second, commercial vehicles, especially electric trucks, are in complex road conditions and high-intensity vibration environments for a long time, and the vehicle-mounted high-voltage hardware (such as contactors, relays, etc.) is prone to failure due to long-term vibration, making it difficult to guarantee reliability; third, once the vehicle-mounted equalization hardware fails, the vehicle's high-voltage system needs to be repaired, resulting in high maintenance costs and long downtime. Summary of the Invention

[0005] This invention provides a battery branch offline balancing device and method to solve the technical problems of high initial and maintenance costs of vehicle hardware and difficulty in guaranteeing reliability in existing vehicle active balancing solutions.

[0006] In a first aspect, a battery branch offline balancing device is provided, comprising: High-voltage busbar; Multiple high-voltage interface groups are used to connect to each battery branch of a multi-branch battery system; The branch switch unit includes multiple sets of branch contactors that correspond one-to-one with multiple high-voltage interface groups. Each set of branch contactors is located between the corresponding high-voltage interface group and the high-voltage busbar. Energy transfer unit, connected to the high-voltage busbar; A switching unit is located between the energy transfer unit and multiple high-voltage interface groups; The control unit, connected to the branch switch unit, energy transfer unit, and switching unit, is configured as follows: Control the closing of the contactors corresponding to all healthy branches, so that they are connected in parallel to the high-voltage bus to form a reference voltage; The control switching unit connects the high-voltage interface group corresponding to the faulty branch to the energy transfer unit, and controls the contactor of the branch corresponding to the faulty branch to disconnect. If the absolute value of the difference between the voltage of the faulty branch and the reference voltage is not less than the preset safety threshold, the energy transfer unit is controlled to transfer energy between the faulty branch and the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold. The contactor of the branch corresponding to the faulty branch is closed, so that it is connected in parallel to the high-voltage bus.

[0007] In some embodiments, the battery branch offline equalization device further includes: The positive main contactor and the pre-charge unit include a pre-charge contactor and a pre-charge resistor. The positive main contactor is connected in series on the positive bus of the high-voltage bus between the branch switch unit and the energy transfer unit. The pre-charge contactor and the pre-charge resistor are connected in series and then in parallel across the two ends of the positive main contactor. The control of closing the contactors corresponding to all healthy branches, connecting them in parallel to the high-voltage bus to form a reference voltage, includes: First, close the pre-charge contactor. After the voltage of the high-voltage bus reaches the preset voltage value, close the positive main contactor and disconnect the pre-charge contactor.

[0008] In some embodiments, the energy transfer unit is a bidirectional DC-DC converter, which has a first set of ports and a second set of ports. The first set of ports is connected to the high-voltage bus, and the second set of ports is connected to the switching unit. If the absolute value of the difference between the voltage of the faulty branch and the reference voltage is not less than a preset safety threshold, the energy transfer unit is controlled to transfer energy between the faulty branch and the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold, including: If the voltage of the faulty branch is lower than the reference voltage, the energy transfer unit is controlled to operate in step-down mode to transfer energy from the high-voltage bus to the faulty branch until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than a preset safety threshold. If the voltage of the faulty branch is higher than the reference voltage, the energy transfer unit is controlled to operate in boost mode to transfer energy from the faulty branch to the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than a preset safety threshold.

[0009] In some embodiments, the switching unit includes two common terminals and N sets of contacts, where N is the number of high-voltage interface groups; the two common terminals are respectively connected to the positive and negative terminals of the second set of ports; and the N sets of contacts are respectively connected to the positive and negative terminals of the N high-voltage interface groups.

[0010] In some embodiments, the battery branch offline equalization device further includes: Multiple current detection modules are provided, one-to-one, between multiple sets of branch contactors and multiple sets of high-voltage interface groups, and the multiple current detection modules are connected to the control unit.

[0011] In some embodiments, the battery branch offline equalization device further includes: The voltage detection module is connected to the high-voltage bus and the control unit.

[0012] In some embodiments, the battery branch offline equalization device further includes: A low-voltage communication interface is used to connect to the battery management system of a multi-branch battery system.

[0013] Secondly, an offline equalization method for battery branches is provided, including the following steps: Control the closing of the contactors corresponding to all healthy branches, so that they are connected in parallel to the high-voltage bus to form a reference voltage; The control switching unit connects the high-voltage interface group corresponding to the faulty branch to the energy transfer unit, and controls the contactor of the branch corresponding to the faulty branch to disconnect. If the absolute value of the difference between the voltage of the faulty branch and the reference voltage is not less than the preset safety threshold, the energy transfer unit is controlled to transfer energy between the faulty branch and the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold. The contactor of the branch corresponding to the faulty branch is closed, so that it is connected in parallel to the high-voltage bus.

[0014] In some embodiments, the step of controlling the closing of the contactors corresponding to all healthy branches, connecting them in parallel to the high-voltage bus to form a reference voltage, further includes: First, close the pre-charge contactor. After the voltage of the high-voltage bus reaches the preset voltage value, close the positive main contactor and open the pre-charge contactor.

[0015] In some embodiments, if the absolute value of the difference between the voltage of the faulty branch and the reference voltage is not less than a preset safety threshold, the energy transfer unit is controlled to transfer energy between the faulty branch and the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold, including: If the voltage of the faulty branch is lower than the reference voltage, the energy transfer unit is controlled to operate in step-down mode to transfer energy from the high-voltage bus to the faulty branch until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold. If the voltage of the faulty branch is higher than the reference voltage, the energy transfer unit is controlled to operate in boost mode to transfer energy from the faulty branch to the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold.

[0016] The beneficial effects of the technical solution provided by this invention include: This invention provides a battery branch offline balancing device and method. The battery branch offline balancing device integrates a branch switching unit, an energy transfer unit, and a switching unit into an external independent device. It controls all healthy branches to be connected in parallel to the high-voltage bus to form a system reference voltage. Then, faulty branches are isolated and connected to the energy transfer unit for energy transfer until the absolute value of the voltage difference is less than a preset safety threshold before closing the branch contactor for grid connection. One set of this invention can serve all vehicles of the same type in an entire fleet, eliminating the maintenance costs of onboard high-voltage hardware. It is not affected by long-term vehicle vibration and has high reliability. It solves the technical problems of high per-vehicle cost, susceptibility to failure in vibration environments, and high maintenance complexity caused by the configuration of high-voltage balancing hardware in existing onboard multi-branch power battery systems. It achieves the beneficial effects of zero onboard high-voltage hardware configuration, precise voltage matching, and shock-free branch grid connection. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic block diagram of a battery branch offline balancing device provided in an embodiment of the present invention; Figure 2 Another principle block diagram of a battery branch offline equalization device provided in an embodiment of the present invention; Figure 3 A flowchart illustrating a battery branch offline balancing method provided in an embodiment of the present invention; Figure 4Implementation provided for the embodiments of the present invention Figure 3 A flowchart of step S300. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention provides a battery branch offline balancing device, which can solve the technical problems of high initial and maintenance costs of vehicle hardware in existing vehicle active balancing solutions, and difficulty in guaranteeing reliability.

[0021] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a battery branch offline balancing device. This device is a mobile, independent unit, not fixedly installed on a vehicle. It is primarily used in maintenance scenarios involving multi-branch power battery systems, such as those found in electric trucks. The battery branch offline balancing device includes a high-voltage bus, multiple high-voltage interface groups, a branch switch unit, an energy transfer unit, a switching unit, and a control unit.

[0022] The high-voltage busbar includes the positive busbar Bus_P on the branch side, the positive busbar Bus_P_DC on the energy transfer side, and the negative busbar Bus_N.

[0023] Multiple high-voltage interface groups include multiple external high-voltage positive interfaces (P1+...PN+) and high-voltage negative interfaces (P1-...PN-), used to connect to each battery branch of the multi-branch battery system respectively. During actual maintenance, the repair personnel physically disconnect all branches of the vehicle's multi-branch battery system from the original vehicle wiring harness and connect them to the high-voltage interface groups of the battery branch offline balancing device of this embodiment of the invention via high-voltage balancing cables.

[0024] The branch switch unit includes multiple sets of branch contactors that correspond one-to-one with multiple high-voltage interface groups. Each set of branch contactors is located between the corresponding high-voltage interface group and the high-voltage busbar, and is used to control the connection and disconnection of each branch with the high-voltage busbar.

[0025] The energy transfer unit is connected to the high-voltage bus (positive bus Bus_P_DC). Optionally, the energy transfer unit is a bidirectional DC-DC converter. The bidirectional DC-DC converter has a first set of ports (port A+, port A-) and a second set of ports (port B+, port B-). The first set of ports (port A+, port A-) is connected to the high-voltage bus (positive bus Bus_P_DC), and the second set of ports (port B+, port B-) is connected to the switching unit.

[0026] A switching unit is located between the energy transfer unit and multiple high-voltage interface groups, used to selectively connect a branch to the energy transfer unit. In this embodiment, the switching unit is a double-pole double-throw switch, including two common terminals (COM+, COM-) and N sets of contacts, where N is the number of high-voltage interface groups. Each set of contacts corresponds to a branch, including a positive contact SWi+ and a negative contact SWi-. COM+ is connected to port B+; COM- is connected to port B-; SWi+ of each set of contacts is connected to the corresponding branch's positive high voltage (before the branch's positive contactor); SWi- of each set of contacts is connected to the corresponding branch's negative high voltage (between the branch's negative contactor and the branch's current sensor). Through the switching unit, any branch can be individually connected to the energy transfer unit while being electrically isolated from other branches.

[0027] The control unit (e.g., a microprocessor MCU) is connected to the branch switch unit, the energy transfer unit, and the switching unit. The control unit is configured as follows: First, the contactors corresponding to all healthy branches are closed, connecting all healthy branches in parallel to the high-voltage bus to form a reference voltage. At this point, the voltage of the high-voltage bus is the average voltage after all healthy branches are connected in parallel, representing the true state of the current battery system. A healthy branch refers to a battery branch whose voltage and SOC are both within the normal range.

[0028] Secondly, the control switching unit connects the high-voltage interface group corresponding to the faulty branch (i.e., the branch that needs maintenance or replacement) to the energy transfer unit, and controls the corresponding branch contactor to disconnect. At this time, the faulty branch is only connected to the energy transfer unit and is not directly connected in parallel to the high-voltage bus. The faulty branch refers to the battery branch whose voltage or SOC is outside the normal range and needs to be replaced.

[0029] Next, the voltage of the faulty branch and the reference voltage of the high-voltage bus are acquired. If the absolute value of the difference between the voltage of the faulty branch and the reference voltage is not less than a preset safety threshold, the energy transfer unit is controlled to transfer energy between the faulty branch and the high-voltage bus. Specifically, if the voltage of the faulty branch is lower than the reference voltage, the energy transfer unit is controlled to operate in buck mode, transferring energy from the high-voltage bus to the faulty branch to charge it until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold. If the voltage of the faulty branch is higher than the reference voltage, the energy transfer unit is controlled to operate in boost mode, transferring energy from the faulty branch to the high-voltage bus to discharge it until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold.

[0030] Finally, the contactor corresponding to the faulty branch is closed, connecting it in parallel to the high-voltage bus. Since the voltage is now consistent, no inrush current will be generated when the contactor is closed.

[0031] The battery branch offline balancing device in this embodiment integrates the branch switching unit, energy transfer unit, and switching unit into an external independent device. It controls all healthy branches to be connected in parallel to the high-voltage bus to form a system reference voltage. Then, it isolates faulty branches and connects them to the energy transfer unit for energy transfer until the absolute value of the voltage difference is less than a preset safety threshold before closing the branch contactor for grid connection. One set of this device can serve all vehicles of the same type in the entire fleet, eliminating the maintenance costs of onboard high-voltage hardware. It is not affected by long-term vehicle vibration and has high reliability. It solves the technical problems of high per-vehicle cost, susceptibility to failure in vibration environments, and high maintenance complexity caused by the configuration of high-voltage balancing hardware in existing onboard multi-branch power battery systems. It achieves the beneficial effects of zero onboard high-voltage hardware configuration, precise voltage matching, and shock-free branch grid connection.

[0032] In an optional embodiment of the invention, such as Figure 2 As shown, the battery branch offline balancing device further includes: a positive main contactor (Kmain) and a pre-charge unit. The pre-charge unit includes a pre-charge contactor (Kpre) and a pre-charge resistor (R). The positive main contactor is connected in series on the positive bus (positive bus Bus_P_DC) of the high-voltage bus between the branch switching unit and the energy transfer unit. The pre-charge contactor and the pre-charge resistor are connected in series and then in parallel across the two ends of the positive main contactor.

[0033] The control of closing the contactors corresponding to all healthy branches, connecting them in parallel to the high-voltage bus to form a reference voltage, includes: First, the pre-charge contactor is closed. At this time, the first healthy branch connected charges the bus capacitor (Cbus) of the high-voltage bus through the pre-charge resistor. Due to the current limiting effect of the resistor, the charging current is limited to a safe range. After the voltage of the high-voltage bus reaches the preset voltage value (e.g., close to the branch voltage), the positive main contactor is closed and the pre-charge contactor is opened. Then, other healthy branches are connected in sequence. This avoids the impact of large current on the bus capacitor.

[0034] In an optional embodiment of the invention, such as Figure 2 As shown, the battery branch offline balancing device further includes: multiple current detection modules, which are respectively installed between multiple sets of branch contactors and multiple sets of high-voltage interface groups. The multiple current detection modules are connected to the control unit to monitor the current of each branch in real time and prevent overcurrent. Figure 2 A1, A2, and A3 in the diagram can be understood as current detection modules on three branches, and these current detection modules can be Hall sensors.

[0035] In an optional embodiment of the invention, the battery branch offline balancing device further includes a voltage detection module connected to the high-voltage bus and the control unit for accurately measuring the reference voltage.

[0036] In an optional embodiment of the invention, such as Figure 2 As shown, the battery branch offline balancing device also includes a low-voltage communication interface for connecting to the battery management system (BMS) of the multi-branch battery system. Through the low-voltage communication interface, the control unit can read detailed information of the battery branch or send maintenance status signals to the vehicle BMS.

[0037] In an optional embodiment of the invention, such as Figure 2 As shown, the battery branch offline equalization device may also include a human-machine interface and a low-voltage power supply module. The human-machine interface is used to display the status and receive commands, and the low-voltage power supply module supplies power to the internal circuit of the device, which can be powered by a built-in battery or an external power source.

[0038] like Figure 3 As shown, this embodiment of the invention provides a battery branch offline balancing method, including the following steps: Step S100: Control the closing of the contactors corresponding to all healthy branches, so that they are connected in parallel to the high-voltage bus to form a reference voltage.

[0039] Step S200: Control the switching unit to connect the high-voltage interface group corresponding to the faulty branch to the energy transfer unit, and control the contactor of the branch corresponding to the faulty branch to disconnect. Step S300: If the absolute value of the difference between the voltage of the faulty branch and the reference voltage is not less than the preset safety threshold, control the energy transfer unit to transfer energy between the faulty branch and the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold. Step S400: Control the contactor of the branch corresponding to the faulty branch to close, so that it is connected in parallel to the high-voltage bus.

[0040] The embodiments of the present invention achieve zero-vehicle-mounted high-voltage hardware configuration, precise voltage matching, and branch-circuit-free grid connection through the above methods, ensuring the safety and efficiency of the maintenance process.

[0041] In an optional embodiment of the invention, the step of controlling the closing of the contactors corresponding to all healthy branches, connecting them in parallel to the high-voltage bus to form a reference voltage, further includes: First, close the pre-charge contactor. After the voltage of the high-voltage bus reaches the preset voltage value, close the positive main contactor and open the pre-charge contactor.

[0042] The first healthy branch connected charges the bus capacitor of the high-voltage bus through a pre-charging resistor. Due to the current limiting effect of the resistor, the charging current is kept within a safe range. Once the voltage of the high-voltage bus reaches the preset voltage value (e.g., close to the branch voltage), the positive main contactor is closed and the pre-charging contactor is opened. After that, other healthy branches are connected in sequence. This avoids large current impacting the bus capacitor.

[0043] In an optional embodiment of the invention, such as Figure 4 As shown, if the absolute value of the difference between the voltage of the faulty branch and the reference voltage is not less than a preset safety threshold, the energy transfer unit is controlled to transfer energy between the faulty branch and the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold, including: Step S301: If the voltage of the faulty branch is lower than the reference voltage, control the energy transfer unit to operate in step-down mode to transfer energy from the high-voltage bus to the faulty branch until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than a preset safety threshold.

[0044] Step S302: If the voltage of the faulty branch is higher than the reference voltage, control the energy transfer unit to operate in boost mode and transfer energy from the faulty branch to the high-voltage bus.

[0045] Specifically, the control unit calculates the absolute value of the difference between the voltage of the faulty branch and the reference voltage, ΔV = |V_fault - V_bus|: If ΔV is less than the preset safety threshold Vth, then no balancing is required; If ΔV≥Vth, then according to the magnitude relationship between V_fault and V_bus, control the operation of the energy transfer unit: If V_fault > V_bus, the energy transfer unit operates in the boost mode, and energy flows from the faulty branch to the high-voltage bus and is absorbed by all healthy branches; If V_fault < V_bus, the energy transfer unit operates in the buck mode, and energy flows from the high-voltage bus to the faulty branch and is provided by all online healthy branches.

[0046] The following uses a specific case to illustrate the process of the battery branch offline equalization method as follows: As Figure 2 shown, assume there are 3 branches, where branch 1 and branch 3 are healthy branches with a voltage of 650V, and branch 2 is a faulty branch. After replacing the battery pack, perform the following operating steps: Step A1: The target branch (assumed to be branch 2) is maintained and ready for grid connection.

[0047] Step A2: Pull out the high-voltage plugs and low-voltage plugs connecting all three branches (branches 1, 2, and 3) to the vehicle.

[0048] Step A3: Connect the three groups of high-voltage equalization cables of the device to the total positive and total negative interfaces of the battery packs in the three branches respectively, and connect the other ends to the high-voltage interfaces (P1+, P2+, P3+, P1-, P2-, P3-) of the device. Connect the low-voltage communication cable device to the BMS.

[0049] Step A4: Select the first online healthy branch (such as branch 1), and close its corresponding branch positive contactor K1_P and branch negative contactor K1_N.

[0050] Step A5: Close the pre-charge contactor Kpre, and pre-charge the bus capacitor Cbus through the pre-charge resistor R.

[0051] Step A6: Monitor the voltage of Cbus. When it rises close to the voltage of branch 1, close the branch positive contactor K3_P and branch negative contactor K3_N of the other online healthy branch (branch 3).

[0052] Step A7: Close the main positive contactor Kmain and disconnect the pre-charge contactor Kpre. At this time, branches 1 and 3 are directly connected in parallel through Bus_P and Bus_N, and the bus voltage V_bus is stabilized at 650V.

[0053] Step A8: Control the switching switch unit to connect COM+ and COM- to the contacts SW2+ and SW2- of branch 2, so that the port B of the energy transfer unit is connected to the positive and negative poles of branch 2.

[0054] Step A9: The control unit obtains the voltage of branch 2, V_fault = 620V, from the BMS through low-voltage communication, and measures the bus voltage V_bus = 650V (which can be obtained through the voltage detection unit).

[0055] Step A10: Calculate ΔV = V_bus - V_fault = 30V, compare it with the preset threshold Vth = 3V. Since ΔV > Vth, the control unit determines that balancing is required.

[0056] Step A11: Since V_fault < V_bus, control the energy transfer unit to operate in the step-down mode, and charge branch 2 with a constant current of 20A from branch 1 and branch 3.

[0057] Step A12: Monitor ΔV and the balancing current value in real time. When ΔV < Vth (for example, it drops to 2V), stop the energy transfer unit.

[0058] Step A13: Control the switching switch unit to disconnect the connection with branch 2.

[0059] Step A14: Close the positive contactor K2_P and the negative contactor K2_N of branch 2, and directly connect branch 2 in parallel to the bus.

[0060] Step A15: The device gives an audible and visual prompt, and the maintenance personnel unplug all plugs.

[0061] Step A16: Restore the original vehicle's high-voltage and low-voltage connections for the three branches, and the balancing process ends.

[0062] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. Unless otherwise clearly specified and defined, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0063] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0064] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A battery branch offline balancing device, characterized in that, include: High-voltage busbar; Multiple high-voltage interface groups are used to connect to each battery branch of a multi-branch battery system; The branch switch unit includes multiple sets of branch contactors that correspond one-to-one with multiple high-voltage interface groups. Each set of branch contactors is located between the corresponding high-voltage interface group and the high-voltage busbar. Energy transfer unit, connected to the high-voltage busbar; A switching unit is located between the energy transfer unit and multiple high-voltage interface groups; The control unit, connected to the branch switch unit, energy transfer unit, and switching unit, is configured as follows: Control the closing of the contactors corresponding to all healthy branches, so that they are connected in parallel to the high-voltage bus to form a reference voltage; The control switching unit connects the high-voltage interface group corresponding to the faulty branch to the energy transfer unit, and controls the contactor of the branch corresponding to the faulty branch to disconnect. If the absolute value of the difference between the voltage of the faulty branch and the reference voltage is not less than the preset safety threshold, the energy transfer unit is controlled to transfer energy between the faulty branch and the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold. The contactor of the branch corresponding to the faulty branch is closed, so that it is connected in parallel to the high-voltage bus.

2. The battery branch offline balancing device according to claim 1, characterized in that, Also includes: The positive main contactor and the pre-charge unit include a pre-charge contactor and a pre-charge resistor. The positive main contactor is connected in series on the positive bus of the high-voltage bus between the branch switch unit and the energy transfer unit. The pre-charge contactor and the pre-charge resistor are connected in series and then in parallel across the two ends of the positive main contactor. The control of closing the contactors corresponding to all healthy branches, connecting them in parallel to the high-voltage bus to form a reference voltage, includes: First, close the pre-charge contactor. After the voltage of the high-voltage bus reaches the preset voltage value, close the positive main contactor and disconnect the pre-charge contactor.

3. The battery branch offline balancing device according to claim 2, characterized in that: The energy transfer unit is a bidirectional DC-DC converter. The bidirectional DC-DC converter has a first set of ports and a second set of ports. The first set of ports is connected to the high-voltage bus, and the second set of ports is connected to the switching unit. If the absolute value of the difference between the voltage of the faulty branch and the reference voltage is not less than a preset safety threshold, the energy transfer unit is controlled to transfer energy between the faulty branch and the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold, including: If the voltage of the faulty branch is lower than the reference voltage, the energy transfer unit is controlled to operate in step-down mode to transfer energy from the high-voltage bus to the faulty branch until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than a preset safety threshold. If the voltage of the faulty branch is higher than the reference voltage, the energy transfer unit is controlled to operate in boost mode to transfer energy from the faulty branch to the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than a preset safety threshold.

4. The battery branch offline balancing device according to claim 3, characterized in that: The switching unit includes two common terminals and N sets of contacts, where N is the number of high-voltage interface groups; the two common terminals are respectively connected to the positive and negative terminals of the second group of ports; the N sets of contacts are respectively connected to the positive and negative terminals of the N high-voltage interface groups.

5. The battery branch offline balancing device according to claim 1, characterized in that, Also includes: Multiple current detection modules are provided, one-to-one, between multiple sets of branch contactors and multiple sets of high-voltage interface groups, and the multiple current detection modules are connected to the control unit.

6. The battery branch offline balancing device according to claim 1, characterized in that, Also includes: The voltage detection module is connected to the high-voltage bus and the control unit.

7. The battery branch offline balancing device according to claim 1, characterized in that, Also includes: A low-voltage communication interface is used to connect to the battery management system of a multi-branch battery system.

8. A battery branch offline balancing method based on the battery branch offline balancing device according to any one of claims 1 to 7, characterized in that, Includes the following steps: Control the closing of the contactors corresponding to all healthy branches, so that they are connected in parallel to the high-voltage bus to form a reference voltage; The control switching unit connects the high-voltage interface group corresponding to the faulty branch to the energy transfer unit, and controls the contactor of the branch corresponding to the faulty branch to disconnect. If the absolute value of the difference between the voltage of the faulty branch and the reference voltage is not less than the preset safety threshold, the energy transfer unit is controlled to transfer energy between the faulty branch and the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold. The contactor of the branch corresponding to the faulty branch is closed, so that it is connected in parallel to the high-voltage bus.

9. The battery branch offline balancing method according to claim 8, characterized in that, The method of controlling the closing of the contactors corresponding to all healthy branches, so that they are connected in parallel to the high-voltage bus to form a reference voltage, also includes: First, close the pre-charge contactor. After the voltage of the high-voltage bus reaches the preset voltage value, close the positive main contactor and open the pre-charge contactor.

10. The battery branch offline balancing method according to claim 8, characterized in that, If the absolute value of the difference between the voltage of the faulty branch and the reference voltage is not less than a preset safety threshold, the energy transfer unit is controlled to transfer energy between the faulty branch and the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold, including: If the voltage of the faulty branch is lower than the reference voltage, the energy transfer unit is controlled to operate in step-down mode to transfer energy from the high-voltage bus to the faulty branch until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold. If the voltage of the faulty branch is higher than the reference voltage, the energy transfer unit is controlled to operate in boost mode to transfer energy from the faulty branch to the high-voltage bus until the absolute value of the difference between the voltage of the faulty branch and the reference voltage is less than the preset safety threshold.

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