Cross-battery-pack energy transfer system oriented to multi-pack parallel architecture and control method

Abstract

The invention discloses a multi-pack parallel architecture-oriented cross-battery pack energy transfer system and a control method. The system comprises a plurality of battery packs, a direct current bus bar, a main controller and a capacitor array subsystem, the plurality of battery packs are connected in parallel on the direct-current bus busbar; the capacitor array subsystem comprises a capacitor array and a measurement module, the capacitor array is connected with any battery pack through a switch matrix, and the measurement module is used for collecting a capacitor state signal and uploading the capacitor state signal to the main controller; and the main controller is used for dynamically generating a capacitance control signal according to the state of the battery pack and sending the capacitance control signal to the capacitance array subsystem. According to the invention, rapid and safe energy transfer across the battery packs can be realized, active equalization of the battery packs in different voltage states can be rapidly completed, so that the voltage consistency of a multi-pack system is maintained, the influence of a wooden barrel effect on the charging and discharging capability of the battery system is effectively avoided, the maximum charging and discharging capability of the multi-pack system is released, and the service life of the battery system is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of battery management technology, and more specifically, relates to a cross-battery pack energy transfer system and control method for multi-pack parallel architecture. Background Technology

[0002] With the increasing demand for high-capacity, high-voltage battery systems in the new energy vehicle and construction machinery sectors, single-pack solutions can no longer meet the requirements for range and power output. Multi-stage high-voltage architectures with multiple battery packs connected in parallel have become the mainstream technology. However, when multiple battery packs are used in parallel, differences in initial capacity and aging processes make it difficult to maintain consistent voltage / SOC (State of Charge), leading to a decrease in overall system utilization. Current solutions typically use conventional single-cell balancing for passive balancing, or passive balancing through inter-pack circulating current when multiple battery packs are simultaneously connected to the busbar. These solutions suffer from low energy transfer efficiency and lack effective methods for controlling balancing across battery packs.

[0003] Existing technical solutions include: Cell-level passive balancing schemes detect cell voltage, estimate the magnitude of capacity differences between cells and the balancing time required using a capacity difference model, and then activate the balancing resistor of the corresponding cell to discharge, thereby reducing the state of charge of the high-voltage cell and achieving passive balancing. However, cell-level passive balancing has a relatively small balancing current, mainly relying on the balancing resistor to directly convert excess electricity into heat, resulting in extremely low balancing efficiency and failing to meet the rapid balancing requirements of multi-cell parallel architectures.

[0004] Based on battery pack-level active balancing schemes, in multi-pack architectures, some technical solutions involve connecting an independent bidirectional DC-DC converter (DC-DC converter) in series with each battery pack, or configuring an independent balancing switch. When the voltage difference between battery packs exceeds a set threshold, the DC-DC current is controlled to flow towards the balancing switch or the balancing switch is closed, enabling energy transfer between battery packs. Inter-pack balancing schemes using DC-DC converters or balancing switches typically require a balancing resistor in series in the circuit to limit transient large currents under high and low voltage differences, avoiding overcurrent and thermal runaway risks. However, the balancing current is limited by the balancing resistor, significantly reducing energy transfer efficiency. Another approach is to directly utilize the DC bus as the energy transfer channel, connecting high-voltage and low-voltage battery packs directly in parallel via the bus to achieve rapid cross-pack energy flow. However, this method lacks an effective current regulation mechanism; when the voltage difference between packs is large, excessive inrush current may be generated at the moment the relay closes, leading to relay melting and contact sticking.

[0005] In a multi-battery pack parallel architecture, voltage differences between battery packs during high-voltage operation can cause a large current to flow when the relay closes, leading to relay melting and sticking. Therefore, there is an urgent need for a new energy transfer system and control method for multi-battery pack parallel architectures to address the shortcomings and deficiencies of existing technologies. Summary of the Invention

[0006] The purpose of this invention is to address the above-mentioned shortcomings by providing a cross-battery pack energy transfer system and control method for multi-pack parallel architectures. This solves the problems mentioned in the background art by utilizing capacitor arrays and switch matrices to construct intermediate energy buffers and transfer channels, enabling rapid and safe energy transfer across battery packs. It also enables rapid active balancing of battery packs under different voltage states to maintain voltage consistency in the multi-pack system, effectively avoiding the impact of the "weakest link" effect on the charging and discharging capacity of the battery system, releasing the maximum charging and discharging capacity of the multi-pack system, and extending the service life of the battery system.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a cross-battery pack energy transfer system for a multi-pack parallel architecture, comprising several battery packs, a DC bus, a main controller, and a capacitor array subsystem; The battery packs are connected in parallel to the DC bus. The capacitor array subsystem includes a capacitor array and a measurement module. The capacitor array is connected to any battery pack through a switch matrix. The measurement module is used to collect capacitor status signals and upload the capacitor status signals to the main controller. The main controller is connected to the battery pack and the capacitor array subsystem respectively, and is used to dynamically generate capacitor control signals according to the state of the battery pack and send them to the capacitor array subsystem.

[0008] Furthermore, several of the battery packs can be directly connected in parallel to the DC bus, or each battery pack can be connected in parallel to the DC bus after an independent DC-DC converter connected in series.

[0009] Furthermore, the capacitor array includes multiple capacitor units distributed in a matrix and supporting parallel operation to improve the energy transfer rate across the battery pack.

[0010] Furthermore, the capacitor array is connected to a switch matrix via a current limiting unit to limit the peak current during the rapid charging and discharging process of the capacitor array. The switch matrix enables the capacitor array to establish a controllable connection with any battery pack, flexibly facilitating energy transfer across battery packs.

[0011] Furthermore, the current limiting unit is a controllable current limiting device, with each capacitor unit connected to a controllable current limiting device, which can be a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) used to adjust the duty cycle to control the current.

[0012] Furthermore, the measurement module includes a current detection unit, a voltage detection unit, and a temperature detection unit, and the collected capacitor status signals include capacitor voltage, capacitor current, and capacitor temperature; the battery pack status includes battery pack voltage, SOC, and battery pack temperature.

[0013] Furthermore, the capacitor control signal includes the target charging voltage and target discharging path of the capacitor unit.

[0014] Secondly, the present invention also provides a cross-battery pack energy transfer control method for a multi-pack parallel architecture, based on the cross-battery pack energy transfer system for a multi-pack parallel architecture described in the first aspect, the control method comprising: When all relays in the battery pack are disconnected, the main controller enters sleep mode. When the sleep time reaches the preset sleep duration, the main controller is woken up via CAN (Controller Area Network). The main controller determines the maximum voltage U of the battery pack within the battery system. i and the minimum voltage U of the battery pack j The voltage difference, when this voltage difference is greater than the inter-packet equalization activation threshold U thstart At that time, select the battery pack with the highest voltage. i and minimum voltage battery pack j As an active balancing battery pack pair, the capacitor array subsystem is activated to perform active balancing; the active balancing process includes: first, balancing the battery pack with the highest voltage... i The capacitor array subsystem is charged, and then the low-voltage battery pack is discharged through the capacitor array subsystem. When the battery pack maximum voltage U i and the minimum voltage U of the battery pack j The voltage difference is less than the inter-cabin equalization threshold U thstart At this time, the main controller ends the active balancing process and switches the capacitor array subsystem to standby mode.

[0015] In this invention, i and j are the serial numbers of the battery pack, i, j∈(1,2,...,N); N is a natural number greater than 2.

[0016] In the above method, the sleep duration can be timed by the RTC (Real-Time Clock) module; the preset sleep duration is ≥30min.

[0017] Furthermore, the battery pack with maximum voltagei Charging the capacitor array subsystem includes: The main controller drives the switch matrix to close, connecting the capacitor array to the battery pack. i Battery Pack i The capacitor array is charged through a current limiting unit; When the capacitor array voltage reaches the preset threshold U max At ±5V, the main controller drives the switching matrix to disconnect, allowing the capacitor array to connect with the battery pack. i disconnect; The discharge of the low-voltage battery pack through the capacitor array subsystem includes: The main controller drives the switch matrix to close, connecting the capacitor array to the battery pack. j The capacitor array limits the battery pack through the current limiting unit. j Charge; When the capacitor array voltage reaches the preset threshold U min At ±5V, the controller drives the switching matrix to disconnect, allowing the capacitor array to connect with the battery pack. j disconnect.

[0018] Furthermore, the current limiting unit uses a MOSFET connected in series between the capacitor array and the battery pack. This unit is controlled by a PWM signal, and the duty cycle is initially set to a small value to achieve soft start and prevent inrush current.

[0019] Furthermore, during the charging and / or discharging process, the current value is sampled in real time by the current detection unit in the measurement module. The main controller dynamically adjusts the PWM duty cycle according to the real-time sampled current value and the set target current through the PI regulation algorithm, so that the charging current is stabilized within the set range.

[0020] Furthermore, the control method also includes: During the active balancing process, the main controller continuously judges the PACK. i With PACK j Voltage difference between the two sides; If the voltage difference is greater than the active equalization shutdown threshold U thend Then the active balancing process is repeated until the PACK is complete. i With PACK j The voltage difference between the two sides is less than the active equalization shutdown threshold U. thend When this happens, the active balancing process is stopped.

[0021] In the above technical solution, the active balancing shutdown threshold U thend <Private room equalization threshold U> thstart The specific range of values ​​can be determined based on the voltage magnitude of the actual voltage platform; this invention does not impose any specific limitations.

[0022] Furthermore, the control method also includes: When the selected battery pack pair completes the active balancing process, the main controller again judges the voltage difference between the highest and lowest voltage of the battery pack in the battery system, reselects the battery pack pair that needs to be actively balanced, starts the capacitor array subsystem, and performs the active balancing process until all the battery pack pairs in the battery system have completed the active balancing process.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: The cross-battery pack energy transfer system for multi-pack parallel architecture described in this invention utilizes a capacitor array subsystem and a switch matrix to construct an intermediate energy buffer and transfer channel, enabling rapid and safe energy transfer between different battery packs. It is also scheduled by the main controller to maintain voltage balance across the entire battery system. Furthermore, it can quickly achieve active balancing of battery packs under different voltage conditions to maintain voltage consistency across the multi-pack system, effectively avoiding the "weakest link" effect on the battery system's charging and discharging capabilities, releasing the maximum charging and discharging capacity of the multi-pack system, and extending the battery system's lifespan. This invention connects a capacitor array and a switch matrix through a current limiting unit, which can adjust the duty cycle to control the equalization current, effectively improving equalization efficiency and preventing the risk of overcurrent in the equalization circuit. The cross-battery pack energy transfer method of the present invention, after the battery system is in sleep mode, the main controller starts active balancing according to the SOC / voltage difference between battery packs to perform cross-battery pack energy transfer; the capacitor array subsystem is connected through a switch matrix and can be selectively connected to any battery pack end; the capacitor array, as an energy buffer unit, can realize rapid energy transport of charging-transfer-discharging. The method described in this invention increases the balancing rate, which reduces the voltage between battery packs and effectively avoids the large current that causes the relay to melt and stick together when it closes. By balancing any battery pack through a modular capacitor array subsystem, the overcurrent risk caused by balancing through the DC bus in existing solutions is avoided, and the balancing system is easier to maintain and service. Attached Figure Description

[0024] Figure 1 A system architecture diagram of a cross-battery pack energy transfer system for a multi-pack parallel architecture is provided in an embodiment of the present invention; Figure 2 This is a flowchart illustrating a cross-battery pack energy transfer method for a multi-pack parallel architecture, as provided in an embodiment of the present invention. Detailed Implementation

[0025] Preferred embodiments of the present invention will now be described in more detail with reference to the accompanying drawings and specific examples.

[0026] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0027] Unless the context requires otherwise, throughout the specification and claims, the word “comprising” and its variations, such as “including” and “having”, shall be understood to have an open, inclusive meaning, that is, to be interpreted as “including, but not limited to”.

[0028] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments. Example

[0029] This embodiment provides a cross-battery pack energy transfer system for a multi-pack parallel architecture, such as Figure 1 As shown, the system includes multiple battery packs, a DC bus, a main controller, and a capacitor array subsystem. The battery packs are connected in parallel to the DC bus. The main controller is connected to the battery packs and the capacitor array subsystem via CAN.

[0030] In this embodiment, multiple battery packs are directly connected in parallel to the DC bus; in some other embodiments, a DC-DC converter can be independently connected in series after each battery pack and then connected in parallel to the DC bus.

[0031] In this embodiment, the capacitor array subsystem includes a capacitor array, a measurement module, and a switch matrix. The capacitor array is connected to any battery pack through the switch matrix. The measurement module is used to collect capacitor status signals and upload the capacitor status signals to the main controller.

[0032] In this embodiment, the capacitor array is formed by multiple capacitor units distributed in a matrix. These capacitor units support parallel operation to improve the energy transfer rate across the battery pack. Each capacitor unit in the capacitor array is connected to a switching matrix via a current limiting unit to limit the peak current during the rapid charging and discharging process of the capacitor array. The switching matrix enables the establishment of a controllable connection between the capacitor array and any battery pack, flexibly facilitating energy transfer across battery packs.

[0033] In this embodiment, the current limiting unit is a controllable current limiting device MOSFET, such as... Figure 1 As shown, each capacitor unit is connected to a MOSFET to adjust the duty cycle in order to control the current.

[0034] In this embodiment, the measurement module includes a current detection unit, a voltage detection unit, and a temperature detection unit, such as... Figure 1 As shown, in this embodiment, the current detection unit uses a current sensor to collect the capacitor current, the voltage detection unit uses a voltage sensor to collect the capacitor voltage, and the temperature detection unit uses a temperature sensor to collect the capacitor temperature. In some other embodiments, other feasible detection elements may also be used.

[0035] In this embodiment, the main controller receives the status information of the battery pack, including the battery pack voltage, SOC and battery pack temperature; based on the status of the battery pack, it dynamically determines the charging target voltage and discharging target path of the capacitor unit and sends them to the capacitor array subsystem.

[0036] In this embodiment, the status of the battery pack can be detected using any feasible detection element in the prior art, which will not be elaborated upon in this invention. Example

[0037] This embodiment provides a cross-battery pack energy transfer control method for a multi-pack parallel architecture. Based on the cross-battery pack energy transfer system for a multi-pack parallel architecture described in Embodiment 1, the main controller performs battery pack status detection and determines whether inter-pack equalization needs to be activated.

[0038] Figure 1 This is a flowchart of the control method described in this embodiment. This flowchart only illustrates the logical sequence of the method described in this embodiment. Provided there are no conflicts, different flowcharts may be used in other possible embodiments of the present invention. Figure 1 Complete the steps shown or described in the order indicated.

[0039] The cross-battery pack energy transfer control method for multi-pack parallel architecture provided in this embodiment can be applied to a terminal and can be executed by a cross-battery pack energy transfer control device for multi-pack parallel architecture. This device can be implemented by software and / or hardware and can be integrated into the terminal, such as any smartphone, tablet or computer device with communication function.

[0040] See Figure 1 The control method described in this embodiment specifically includes the following steps: Step 1: After all the relays in the battery pack are disconnected, the main controller enters sleep mode. The RTC module starts to calculate the sleep duration. After the sleep duration is ≥30 minutes, the RTC wakes up the main controller via CAN.

[0041] Step 2: The main controller monitors the battery pack's voltage, SOC, and temperature in real time. When the battery pack's maximum voltage U... i and the minimum voltage U of the battery pack j The voltage difference is greater than the inter-cabin equalization activation threshold U thstart At that time, select the battery pack with the highest voltage. i and minimum voltage battery pack j As an active balancing battery pack pair, the capacitor array subsystem is activated to perform active balancing.

[0042] The active balancing process includes: first, balancing the battery pack with the highest voltage... i The capacitor array subsystem is charged, and then the low-voltage battery pack is discharged through the capacitor array subsystem.

[0043] The charging process includes: the main controller driving the switch matrix to close, causing the capacitor array to be connected to the battery pack. i Battery Pack i The capacitor array is charged through a current limiting unit; when the capacitor array voltage reaches a preset threshold U... max At ±5V, the main controller drives the switching matrix to disconnect, allowing the capacitor array to connect with the battery pack. i disconnect; The discharge process includes: the main controller driving the switch matrix to close, causing the capacitor array to be connected to the battery pack. j The capacitor array limits the battery pack through the current limiting unit. j Charging begins; when the capacitor array voltage reaches the preset threshold U... min At ±5V, the controller drives the switching matrix to disconnect, allowing the capacitor array to connect with the battery pack. j disconnect.

[0044] During the charging and discharging processes described above, the current value is sampled in real time by the current detection unit in the measurement module. The main controller dynamically adjusts the PWM duty cycle based on the real-time sampled current value and the set target current using a PI regulation algorithm to keep the charging current stable within the set range.

[0045] In this embodiment, the current limiting unit MOSFET is connected in series between the capacitor array and the battery pack. It is controlled by a PWM signal, and the duty cycle is initially set to a small value to achieve soft start and prevent inrush current.

[0046] During the active balancing process, the main controller continuously judges the PACK. i With PACK j Voltage difference; if the voltage difference is greater than the active equalization shutdown threshold U thendThen repeat the charging and discharging process described above; if PACK i With PACK j The voltage difference between the two sides is less than the active equalization shutdown threshold U. thend Stop the above active balancing process.

[0047] Step 3: When the selected battery packs complete the active balancing process, the main controller again determines the voltage difference between the highest and lowest voltages of the battery packs within the battery system. If the voltage difference exceeds the inter-pack balancing activation threshold U... thstart When the battery pack is in use, the capacitor array subsystem is activated as a new battery pack pair to perform an active balancing process.

[0048] Step 4: When the battery pack's maximum voltage U i and the minimum voltage U of the battery pack j The voltage difference is less than the inter-cabin equalization threshold U thstart At this time, the main controller ends the active balancing process and switches the capacitor array subsystem to standby mode.

[0049] In this invention, the inter-packet equalization activation threshold U thstart Greater than the active balancing shutdown threshold U thend .

[0050] In this embodiment, the battery pack operates on an 800V voltage platform, and the inter-pack equalization threshold U is... thstart The active equalization off threshold U is set to 20V. thend It is set to 5V. In other embodiments, it can be adjusted according to the voltage level of the voltage platform, etc.

[0051] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and principles of the described embodiments, and these modifications and variations should also be considered within the scope of protection of the present invention.

Claims

1. A cross-battery pack energy transfer system for multi-pack parallel architecture, characterized in that, It includes several battery packs, DC busbars, a main controller, and a capacitor array subsystem; The battery packs are connected in parallel to the DC bus. The capacitor array subsystem includes a capacitor array and a measurement module. The capacitor array is connected to any battery pack through a switch matrix. The measurement module is used to collect capacitor status signals and upload the capacitor status signals to the main controller. The main controller is connected to the battery pack and the capacitor array subsystem respectively, and is used to generate capacitor control signals according to the state of the battery pack and send them to the capacitor array subsystem.

2. The cross-battery pack energy transfer system for multi-pack parallel architecture according to claim 1, characterized in that, Several of the battery packs are directly connected in parallel to the DC bus, or each battery pack is independently connected in series with a DC-DC converter and then connected in parallel to the DC bus.

3. The cross-battery pack energy transfer system for multi-pack parallel architecture according to claim 1, characterized in that, The capacitor array includes multiple capacitor units, which are distributed in a matrix and support parallel operation.

4. The cross-battery pack energy transfer system for multi-pack parallel architecture according to claim 1, characterized in that, The capacitor array is connected to the switch matrix via a current limiting unit.

5. The cross-battery pack energy transfer system for multi-pack parallel architecture according to claim 4, characterized in that, The current limiting unit is a controllable current limiting device.

6. The cross-battery pack energy transfer system for multi-pack parallel architecture according to claim 1, characterized in that, The capacitor status signal includes capacitor voltage, capacitor current, and capacitor temperature; The status of the battery pack includes its voltage, state of charge (SOC), and temperature.

7. The cross-battery pack energy transfer system for multi-pack parallel architecture according to claim 1, characterized in that, The capacitor control signal includes the target charging voltage and target discharging path of the capacitor unit.

8. A method for cross-battery pack energy transfer control for a multi-pack parallel architecture, based on the cross-battery pack energy transfer system for a multi-pack parallel architecture as described in any one of claims 1 to 7, characterized in that, The control method includes: When all relays in the battery pack are disconnected, the main controller enters sleep mode. When the sleep time reaches the preset sleep duration, the main controller is woken up via CAN. The main controller determines the maximum voltage U of the battery pack within the battery system. i and the minimum voltage U of the battery pack j The voltage difference, when this voltage difference is greater than the inter-packet equalization activation threshold U thstart At that time, select the battery pack with the highest voltage. i and minimum voltage battery pack j As an active balancing battery pack pair, the capacitor array subsystem is activated to perform active balancing; the active balancing process includes: first, balancing the battery pack with the highest voltage... i The capacitor array subsystem is charged, and then the low-voltage battery pack is discharged through the capacitor array subsystem. When the battery pack's maximum voltage U i and the minimum voltage U of the battery pack j The voltage difference is less than the inter-cabin equalization threshold U thstart At this time, the main controller ends the active balancing process and switches the capacitor array subsystem to standby mode.

9. The cross-battery pack energy transfer control method for multi-pack parallel architecture according to claim 8, characterized in that, The battery pack that passes the maximum voltage i Charging the capacitor array subsystem includes: The main controller drives the switch matrix to close, connecting the capacitor array to the battery pack. i Battery Pack i The capacitor array is charged through a current limiting unit; When the capacitor array voltage reaches the preset threshold U max At ±5V, the main controller drives the switching matrix to disconnect, allowing the capacitor array to connect with the battery pack. i disconnect; The discharge of the low-voltage battery pack through the capacitor array subsystem includes: The main controller drives the switch matrix to close, connecting the capacitor array to the battery pack. j The capacitor array limits the battery pack through the current limiting unit. j Charge; When the capacitor array voltage reaches the preset threshold U min At ±5V, the controller drives the switching matrix to disconnect, allowing the capacitor array to connect with the battery pack. j disconnect.

10. The cross-battery pack energy transfer control method for multi-pack parallel architecture according to claim 9, characterized in that, During the charging and / or discharging process, the current value is sampled in real time by the measurement module. The main controller dynamically adjusts the PWM duty cycle according to the real-time sampled current value and the set target current through the PI regulation algorithm, so that the charging current is stabilized within the set range.

11. The cross-battery pack energy transfer control method for multi-pack parallel architecture according to claim 8, characterized in that, The control method further includes: During the active balancing process, the main controller continuously judges the PACK. i With PACK j Voltage difference between the two sides; If the voltage difference is greater than the active equalization shutdown threshold U thend Then the active balancing process is repeated until the PACK is complete. i With PACK j The voltage difference between the two sides is less than the active equalization shutdown threshold U. thend When this happens, the active balancing process is stopped.

12. The cross-battery pack energy transfer control method for multi-pack parallel architecture according to claim 8, characterized in that, The control method further includes: When the selected battery pack pair completes the active balancing process, the main controller again judges the voltage difference between the highest and lowest voltage of the battery pack in the battery system, reselects the battery pack pair that needs to be actively balanced, starts the capacitor array subsystem, and performs the active balancing process until all the battery pack pairs in the battery system have completed the active balancing process.

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