Fast-charging vehicle-mounted energy storage system with serial-parallel interaction

Abstract

The application discloses a fast-charging type vehicle-mounted energy storage system capable of serial-parallel interaction, which comprises a battery module unit, a module-level reconfigurable power switch unit, a bidirectional fast-charging interface module and a battery management system, wherein the battery module unit is connected to a DC bus through the power switch unit. The battery management system controls the power switch unit, so that the battery module is dynamically switched between serial output, parallel output and serial-parallel hybrid output modes, and the optimal structure is selected based on voltage deviation, temperature deviation and internal resistance deviation to construct a topology switching constraint condition. The system improves the fast-charging power bearing capacity in the parallel mode, realizes high-voltage output in the serial mode, realizes local balancing control in the hybrid mode, and realizes safe and reliable operation in combination with module health state judgment, bypass protection and topology switching stability constraint. The application can improve the fast-charging performance, battery consistency and system safety, and is suitable for electric vehicle energy storage systems.

Description

Technical Field

[0001] This invention relates to the field of electric vehicles and energy storage control technology, and more specifically to a fast-charging on-board energy storage system that can be connected in series and parallel. Background Technology

[0002] With the rapid development of new energy vehicle technology, the power battery, as the core energy source of electric vehicles, directly determines the vehicle's range, charging efficiency, and lifespan. Currently, most mainstream on-board energy storage systems adopt a fixed series battery pack design, such as 400V or 800V high-voltage platform solutions. However, existing battery systems typically use a fixed series structure, meaning the electrical connections between battery modules cannot be dynamically adjusted. During fast charging, because all battery modules draw the same current, localized heat concentration can easily occur, limiting further increases in the charging rate and thus failing to fully utilize the power capacity of fast charging stations.

[0003] Due to variations in the manufacturing and usage processes of battery modules, their capacity, internal resistance, and temperature characteristics gradually diverge. Existing systems primarily rely on passive balancing or low-power active balancing methods, resulting in low balancing efficiency and difficulty in real-time correction of these differences under high-power operation. Furthermore, in fixed series structures, overheating, overvoltage, or aging anomalies in a single battery module often affect the normal operation of the entire battery string, leading to a decline in overall pack performance or even triggering a protective shutdown, indicating weak system fault tolerance. Moreover, electric vehicles exhibit significant differences in voltage and current requirements under various operating conditions, such as fast charging, low-speed driving, high-speed driving, and energy recovery. Fixed topologies cannot dynamically adjust equivalent output characteristics according to these operating conditions, resulting in low energy utilization efficiency.

[0004] Therefore, there is an urgent need for a series-parallel dynamic reconfiguration energy storage system that can achieve controllable, safe, and rapid response in a vehicle environment to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a fast-charging on-board energy storage system capable of series-parallel interaction, the specific solution of which is as follows:

[0006] Fast-charging on-board energy storage systems that can be interconnected in series and parallel include:

[0007] Battery module unit, module-level reconfigurable power switch unit, bidirectional fast charging interface module and battery management system;

[0008] The battery module unit is connected to the DC bus via a module-level reconfigurable power switch unit.

[0009] The battery management system controls the power switching unit to switch the battery module between series output mode, parallel output mode, and series-parallel hybrid output mode, and the switching is based on topology switching constraints.

[0010] The control steps for the energy storage system are as follows:

[0011] S1. System Initialization and Status Acquisition: After the battery management system starts, it acquires the status of all battery modules. The purpose of this step is to establish a real-time state space model of the battery system. By acquiring key parameters such as voltage, temperature, internal resistance and SOC, it provides basic data support for subsequent topology optimization, thereby avoiding incorrect topology switching when the information is incomplete.

[0012] S2. Topology Evaluation Function Calculation: Cost assessment is performed on series, parallel, and hybrid topologies respectively. The principle is based on reflecting electrical balance through voltage deviation, heat distribution uniformity through temperature deviation, and energy loss level through internal resistance deviation, thereby constructing a unified evaluation standard to achieve optimal selection through multi-physics coupling.

[0013] S3. Working Mode Judgment: The current mode is determined based on the vehicle's operating status. In the case of fast charging, a parallel structure is preferred to reduce the equivalent internal resistance and improve the charging current carrying capacity. In the case of driving, a series structure is used to improve the output voltage level. When there are large differences between modules, a hybrid mode is entered to achieve local balance repair.

[0014] S4. Power Switch Unit Configuration: Based on the S2 control module-level power switch unit, connection configuration is performed. This process uses MOSFET arrays or solid-state relays to realize the conduction, disconnection, and bypass control between battery modules, thereby completing the electrical topology reconstruction at the physical layer and ensuring that the control strategy can be transformed into the actual circuit connection state.

[0015] S5: Fast charging or discharging execution control; In parallel fast charging mode, current adaptive distribution is achieved based on the difference in internal resistance of each module. The principle is that the module with lower internal resistance has lower current path impedance, thus bearing a larger charging current, achieving a natural current sharing effect, and meeting the system power limit constraint, thereby avoiding the risk of local overcurrent and thermal runaway.

[0016] S6: Health status screening and series connection control; It reflects the energy status through SOC, the thermal safety margin through temperature, and the degree of aging through internal resistance, thereby realizing a multi-dimensional judgment of module availability and ensuring that only modules in good health participate in high-voltage series connection, reducing system risks from the source.

[0017] S7: Bypass Protection and Abnormal Handling; When a battery module experiences over-temperature or voltage deviation, the system immediately executes bypass protection. This mechanism quickly cuts off the current path of the abnormal module, causing it to exit the main circuit operation, thereby preventing the local fault from spreading to the entire battery string and improving the system's fault tolerance and operational safety.

[0018] S8: Topology Switching Stability Control: During topology switching, dynamic constraint control is applied to the system output voltage and energy state. The principle is to limit the rate of voltage change, preventing sudden changes in bus voltage due to topology reconfiguration. Simultaneously, energy continuity constraints ensure the energy conservation relationship of the system before and after switching, thereby achieving a smooth transition and reducing the impact on the vehicle's electrical system.

[0019] Furthermore, the topology switching constraints are as follows:

[0020]

[0021] in: Optimal topology

[0022] Topology type: S for series, P for parallel, M for hybrid.

[0023] Voltage deviation of each module

[0024] Temperature deviation

[0025] Internal resistance deviation

[0026] Weighting coefficient.

[0027] Furthermore, in series output mode, the system output voltage satisfies the following condition:

[0028]

[0029] in:

[0030] Output voltage

[0031] : No. Module voltage

[0032] System current

[0033] Module internal resistance.

[0034] Furthermore, the battery management system determines whether to allow participation in a series structure based on the module's health status, and the determination criteria are as follows:

[0035]

[0036] When the following conditions are met:

[0037]

[0038] This module is then allowed to be connected in a series configuration;

[0039] in:

[0040] Module health value

[0041] State of charge

[0042] :temperature

[0043] Internal resistance

[0044] Health threshold

[0045] Weighting coefficient.

[0046] Furthermore, the system meets power constraints in fast charging mode:

[0047]

[0048] in:

[0049] Charging power

[0050] Module voltage

[0051] Module internal resistance.

[0052] Furthermore, bypass protection is implemented when any battery module meets the following conditions:

[0053]

[0054] in:

[0055] State variables

[0056] Average voltage

[0057] Voltage deviation threshold.

[0058] Furthermore, the module-level reconfigurable power switching unit includes a MOSFET array or a solid-state relay; used to realize the on / off and bypass control between battery modules; and the switching response time meets the following requirements:

[0059] .

[0060] Furthermore, the current change constraint is satisfied during the series-parallel switching process:

[0061]

[0062] in:

[0063] Rate of change of current

[0064] : Maximum permissible rate of change.

[0065] Furthermore, in the hybrid output mode, the system performs dynamic equalization control on the battery module through local parallel branches, and its equalization objective function satisfies the following conditions:

[0066]

[0067] in:

[0068] Equilibrium cost function in hybrid mode

[0069] : No. The state of charge of each battery module

[0070] System average state of charge

[0071] : No. Battery module temperature

[0072] System average temperature

[0073] Temperature weighting coefficient

[0074] Furthermore, it enters mixed output mode when the following switching conditions are met:

[0075]

[0076] in:

[0077] SOC inconsistency threshold

[0078] Temperature difference threshold.

[0079] Furthermore, when the battery management system switches between series output mode and parallel output mode, it satisfies the dynamic stability constraints of the topology switching process, which include voltage stability constraints and energy continuity constraints as follows:

[0080]

[0081] in:

[0082] :time Output voltage

[0083] Output voltage at the next moment

[0084] Rated system voltage

[0085] Permissible voltage variation ratio coefficient

[0086]

[0087] in:

[0088] : No. Each battery module at time energy

[0089] Energy loss during system switching

[0090] Number of battery modules.

[0091] Beneficial effects:

[0092] Compared with the prior art, the present invention has the following significant advantages:

[0093] This invention constructs an on-board energy storage system that can be interactively reconfigured in series and parallel, enabling battery modules to dynamically switch between series, parallel, and hybrid topologies according to the vehicle's charging and discharging needs. In fast charging mode, the parallel structure reduces the equivalent internal resistance and achieves reasonable current distribution, while in driving mode, the series structure increases the output voltage level. This allows the system output characteristics to adaptively match the load demand, significantly improving the charging power carrying capacity and overall energy utilization efficiency.

[0094] By introducing comprehensive constraints based on battery module SOC, temperature, and internal resistance, and combining this with a local equalization control mechanism under a hybrid topology, each battery module can gradually converge to uniformity during operation. This effectively suppresses overcharging, over-discharging, and localized heat accumulation caused by individual differences, thereby improving battery consistency and extending battery cycle life. Simultaneously, flexible bypassing and rapid isolation of battery modules are achieved through module-level reconfigurable power switching units. This ensures that over-temperature, over-voltage, or performance abnormalities in a single module do not affect the operation of the entire battery pack, significantly improving overall system safety and fault tolerance.

[0095] Furthermore, this invention employs voltage variation constraints and energy continuity constraints to achieve stability control during topology switching, preventing voltage spikes and energy discontinuities during series-parallel structure switching and ensuring a smooth transition in the topology reconfiguration process, thereby reducing the impact on the vehicle's high-voltage system. Simultaneously, this invention utilizes a module-level power switch architecture based on MOSFET arrays or solid-state relays, exhibiting high compatibility with existing battery management systems. It allows for engineering deployment without redesigning the battery cell system, offering advantages such as clear structure, well-defined control logic, and ease of large-scale application. Attached Figure Description

[0096] Figure 1 It is a control flowchart of a fast-charging on-board energy storage system that can be connected in series and parallel.

[0097] Figure 2 This is a schematic diagram of the overall structure of a fast-charging vehicle-mounted energy storage system that can be connected in series and parallel for interactive operation; Detailed Implementation

[0098] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0099] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0100] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that mutually excludes other embodiments.

[0101] Example 1:

[0102] This embodiment provides a fast-charging on-board energy storage system that can be connected in series and parallel for interactive operation. Figure 2 This is a schematic diagram of the overall structure of a fast-charging on-board energy storage system that can be connected in series and parallel for interactive operation, such as... Figure 2 The device includes a battery module unit, a module-level reconfigurable power switch unit, a bidirectional fast charging interface module, and a battery management system.

[0103] The battery module unit consists of multiple standard battery modules. Each battery module is equipped with a voltage sampling unit, a temperature sampling unit, and an internal resistance estimation module to obtain module status parameters in real time.

[0104] The module-level reconfigurable power switching unit is composed of MOSFET arrays or solid-state relays, used to realize the on, off and bypass control between battery modules, and connected to the DC bus.

[0105] The battery management system calculates the topology switching constraints based on the state parameters of each battery module and outputs the optimal topology Ω, enabling the system to switch between series output mode, parallel output mode, and series-parallel hybrid output mode.

[0106] Figure 1 The attached diagram shows the control flow of a fast-charging on-board energy storage system that can be connected in series and parallel. The system control steps are as follows:

[0107] S1: System Initialization and Status Acquisition

[0108] After the battery management system starts, it collects the status of all battery modules, including: voltage. Current ,temperature Internal resistance SOC value;

[0109] And construct the state vector:

[0110]

[0111] S2: Calculation of topology evaluation function

[0112] Based on the state of each battery module, calculate the deviation function under different topologies:

[0113]

[0114] in:

[0115] S: Series structure

[0116] P: Parallel structure

[0117] M: Hybrid structure

[0118] Obtain the optimal topology

[0119] S3: Working Mode Judgment

[0120] Determine the current mode based on the vehicle's operating status:

[0121] Fast charging mode → Parallel priority mode

[0122] Driving status → Series output mode

[0123] Difference exceeding threshold → Mixed mode

[0124] The judgment conditions include:

[0125]

[0126] or

[0127]

[0128] S4: Power Switching Unit Configuration

[0129] Based on the topology output in step S2, the control module-level power switching unit (MOSFET or solid-state relay array) is connected and configured, and series / parallel reconfiguration is completed.

[0130] S5: Fast charging or discharging control

[0131] If in fast charging mode, parallel current sharing control will be executed:

[0132]

[0133] Simultaneously satisfying power constraints:

[0134]

[0135] S6: Health Status Screening and Serial Access Control

[0136] In series mode, perform a health assessment on the battery module:

[0137]

[0138] when:

[0139]

[0140] If the connection is active, it is allowed to access the serial link; otherwise, it will enter a bypass or hybrid structure.

[0141] S7: Bypass Protection and Anomaly Handling

[0142] Execute protection when an abnormal module is detected:

[0143]

[0144] in:

[0145] Φ_i = 1 indicates that the module is isolated.

[0146] Isolation is achieved by disconnecting the MOSFET array.

[0147] S8: Topology Switching Stability Control

[0148] During the switching between series, parallel, or hybrid modes, the system performs stability control:

[0149] (1) Voltage stability constraint

[0150]

[0151] (2) Energy continuity constraint

[0152]

[0153] (3) Switching completion judgment

[0154] Once the system meets the stability requirements, the topology switchover is confirmed to be complete.

[0155] Example 2:

[0156] This embodiment provides a fast-charging on-board energy storage system that can be interconnected in series and parallel, such as... Figure 1 and Figure 2 As shown, the system is suitable for 400V or 800V electric vehicle platforms and includes a battery module unit, a module-level reconfigurable power switch unit, a bidirectional fast charging interface module, and a battery management system.

[0157] The battery module unit consists of multiple standardized battery modules, such as 12 to 24 cells connected in series to form a module unit. Each module has a rated voltage range of 30V to 60V and a rated capacity of 40Ah to 120Ah. Each module is equipped with voltage sampling, temperature sampling, and internal resistance estimation modules to obtain real-time operating status.

[0158] The module-level reconfigurable power switching unit is composed of MOSFET arrays or solid-state relays, with its on-resistance controlled below 2mΩ, and can complete the on-off or bypass action within 10ms, thereby realizing topology reconfiguration between battery modules.

[0159] The battery management system is used to dynamically adjust the system topology based on the operating status of each battery module, enabling the system to switch between series output mode, parallel output mode, and series-parallel hybrid output mode.

[0160] In actual operation, when the vehicle is in driving mode, the system preferentially adopts a series structure, so that the output voltage of the whole pack can reach the range of 600V to 800V to meet the needs of the drive motor; when the vehicle enters DC fast charging mode, the system switches to a parallel structure, so that the charging current can be increased to the level of 300A to 500A, thereby improving the charging power carrying capacity.

[0161] When the SOC difference between battery modules exceeds 5% or the temperature difference exceeds 5°C, the system enters a hybrid topology mode, which uses local parallel branches to regulate the energy of the modules with differences, so that the system gradually restores consistency.

[0162] During operation, the system comprehensively evaluates different topologies based on voltage difference, temperature difference, and internal resistance difference. For example, if the module voltage deviation, temperature difference, or internal resistance deviation is large under a certain topology, the topology will be determined as a non-optimal structure, and the controller will switch to the topology mode with the smallest deviation.

[0163] In series mode, the battery modules are connected sequentially to form a high-voltage output link. The system output voltage is related to the superposition of the module voltages and is affected by the internal resistance voltage drop. Under typical operating conditions, the system output voltage can be stably maintained in the range of 600V to 800V, and the current varies dynamically according to the driving load, generally ranging from 50A to 200A.

[0164] This mode is mainly used for vehicle acceleration and high-speed driving conditions to reduce current loss and improve energy transmission efficiency.

[0165] In fast charging mode, the system switches to a parallel structure, allowing all battery modules to share the charging current. At this time, the total charging current of the system can reach more than 300A, and the current is automatically distributed according to the difference in internal resistance of each module, so that the module with lower internal resistance bears a higher proportion of the current, thereby achieving a natural current sharing effect.

[0166] This mode can effectively reduce the problem of concentrated heat generation in a single module and improve the safety of fast charging.

[0167] When the system detects significant differences in the states of some modules, such as a SOC deviation exceeding 5% or a temperature difference exceeding 5°C, the system enters hybrid mode. In this mode, some modules are connected in parallel for equalization of charging and discharging, while the remaining modules maintain series output.

[0168] This method can repair local differences without affecting the overall output capacity of the battery pack, thus gradually restoring battery consistency.

[0169] Example 3:

[0170] When the vehicle is undergoing DC fast charging, the system automatically enters the parallel priority control strategy.

[0171] The system charging power can typically reach the range of 120kW to 350kW. By reducing the equivalent internal resistance, the system can withstand higher charging currents.

[0172] During the switching process, in order to avoid sudden current changes, the system limits the rate of current change to prevent significant impact, thereby ensuring a smooth and reliable charging process.

[0173] The specific control process is as follows:

[0174] S01: The system identifies the maximum output power of the charging pile (e.g., 250kW or 350kW).

[0175] S02: Determine the health status of the battery module;

[0176] S03: Switch to parallel topology;

[0177] S04: Perform current sharing control;

[0178] S05: Real-time temperature monitoring;

[0179] S06: Automatically execute bypass protection when a single module malfunctions.

[0180] Example 4:

[0181] In series output mode, to ensure system safety, the battery management system performs a health assessment on each module.

[0182] When the module's SOC is below 10%, its temperature is above 55℃, or its internal resistance increases by more than 20% of the initial value, the module will be deemed a non-ideal module and will not be allowed to participate in a series link.

[0183] This mechanism can effectively prevent aging modules from entering the high-voltage series link, thereby reducing the risk of overall package failure and improving system stability.

[0184] As a further improvement, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fast-charging on-board energy storage system capable of series and parallel interaction, characterized in that, include: Battery module unit, module-level reconfigurable power switch unit, bidirectional fast charging interface module and battery management system; The battery module unit is connected to the DC bus through a module-level reconfigurable power switch unit. The battery management system controls the power switch unit to switch the battery module between series output mode, parallel output mode and series-parallel hybrid output mode. The switching is based on topology switching constraints. The control steps for the energy storage system are as follows: S1. System Initialization and Status Acquisition: After the battery management system starts, it acquires the status of all battery modules. S2, Calculation of topological evaluation function; S3. Working mode determination: Determine the current mode based on the vehicle's operating status; S4. Power Switch Unit Configuration: Connection configuration is based on the S2 control module-level power switch unit; S5: Fast charging or discharging control; S6: Health status screening and serial access control; S7: Bypass protection and anomaly handling; S8: Topology switching stability control.

2. The fast-charging on-board energy storage system with series-parallel interaction as described in claim 1, characterized in that, The topology switching constraints are as follows: in: Optimal topology Topology type: S for series, P for parallel, M for hybrid. Voltage deviation of each module Temperature deviation Internal resistance deviation Weighting coefficient.

3. The fast-charging on-board energy storage system with series-parallel interaction as described in claim 1, characterized in that, In series output mode, the system output voltage satisfies the following condition: in: Output voltage : No. Module voltage System current Module internal resistance.

4. The fast-charging on-board energy storage system with series-parallel interaction as described in claim 1, characterized in that, The battery management system determines whether a module is allowed to participate in a series structure based on its health status, and the criteria for this determination are as follows: When the following conditions are met: This module is then allowed to be connected in a series configuration; in: Module health value State of charge :temperature Internal resistance Health threshold Weighting coefficient.

5. The fast-charging on-board energy storage system with series-parallel interaction as described in claim 1, characterized in that, In fast charging mode, the system meets the power constraint: in: Charging power Module voltage Module internal resistance.

6. The fast-charging on-board energy storage system with series-parallel interaction as described in claim 1, characterized in that, Bypass protection is activated when any battery module meets the following conditions: in: State variables Average voltage Voltage deviation threshold.

7. The fast-charging on-board energy storage system with series-parallel interaction as described in claim 1, characterized in that, The module-level reconfigurable power switching unit includes a MOSFET array or a solid-state relay; it is used to realize the on / off and bypass control between battery modules; and the switching response time meets the following requirements: 。 8. The fast-charging on-board energy storage system with series-parallel interaction as described in claim 1, characterized in that, The current change constraint must be satisfied during the series-parallel switching process: in: Rate of change of current : Maximum permissible rate of change.

9. The fast-charging on-board energy storage system with series-parallel interaction as described in claim 1, characterized in that, In the hybrid output mode, the system performs dynamic equalization control of the battery module through local parallel branches, and its equalization objective function satisfies the following conditions: in: Equilibrium cost function in hybrid mode : No. The state of charge of each battery module System average state of charge : No. Battery module temperature System average temperature Temperature weighting coefficient Furthermore, it enters mixed output mode when the following switching conditions are met: in: SOC inconsistency threshold Temperature difference threshold.

10. The fast-charging on-board energy storage system with series-parallel interaction as described in claim 1, characterized in that, When the battery management system switches between series output mode and parallel output mode, it satisfies the dynamic stability constraints of the topology switching process, which include voltage stability constraints and energy continuity constraints as follows: in: :time Output voltage Output voltage at the next moment Rated system voltage Permissible voltage variation ratio coefficient in: : No. Each battery module at time energy Energy loss during system switching Number of battery modules.

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