State management interface between parallel battery cells, system and control method

Abstract

The application provides a state control interface between parallel battery units, a system and a control method, and belongs to the technical field of batteries. The interface comprises a series type regulating device, a bypass device, a circuit breaking device and a battery management system. A plurality of battery units are connected in parallel to a common DC bus through the interface. The method comprises monitoring the battery state, controlling the series type regulating device to inject a compensation voltage to realize power on-demand distribution and state balance in normal times, and controlling the bypass device and the circuit breaking device to realize fault isolation in fault times. The application can eliminate circulating current, break the "barrel effect", improve the available capacity and service life of the system by actively compensating for the differences between the battery branches through the series controllable voltage ports of the battery branches, integrates the bypass and circuit breaking protection, improves the fault tolerance and power supply continuity of the system, and has high efficiency and economy because the regulating device only processes part of the power.

Description

Technical Field

[0001] This invention relates to the fields of electric vehicles, battery energy storage, and battery secondary utilization, and particularly to a state management interface, system, and control method for parallel battery cells. Background Technology

[0002] Due to inconsistencies in battery manufacturing, operating environment, and aging, the open-circuit voltage and equivalent series resistance of each battery cell vary to different degrees. Battery cells are connected in series to form battery modules and battery clusters with different voltage levels, which can further increase the total power output under voltage level constraints. However, during operation, the state of charge of parallel battery cells will be inconsistent due to the inconsistency of the batteries, especially in the scenario of secondary use. For a group of battery cells connected in direct parallel, there are issues of circulating current and uneven load. Due to differences in open-circuit voltage and internal resistance among the branches, uneven current distribution among the battery cells during parallel charging and discharging can occur, even generating severe inter-branch circulating currents when idle or under light load, greatly accelerating the aging of high-quality batteries. There is also a "weakest link" effect: during charging, one battery cell may be fully charged while others are not. To avoid overcharging the weakest cell, the remaining cells cannot be fully charged. Similarly, during discharging, one battery cell may reach its minimum permissible state of charge while the others can still discharge further. To prevent damage from over-discharging the weakest cell, all parallel and series-connected battery cells will stop discharging. Therefore, the overall usable capacity of a parallel battery system is limited by the weakest battery cell. This parallel mismatch problem results in the incomplete utilization of the capacity of many healthy battery cells, significantly reducing the overall usable capacity of the system.

[0003] Existing battery interface devices or balancing topologies either have limited balancing capabilities, cannot achieve effective collaborative management between parallel battery cells, and are difficult to dynamically adjust the characteristics of parallel ports; or they adopt a full-power conversion architecture, which has drawbacks such as large system size, high cost, and low conversion efficiency.

[0004] Therefore, there is an urgent need in this field for a new type of control device, system architecture and control method that can actively adjust the state between parallel battery cells, while taking into account efficient energy transfer, high reliability and low control cost. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a state management interface, system, and control method for parallel battery cells, which is intended to solve the technical problems existing in existing parallel battery systems, such as circulating current bias, "weakest link" effect, large size, high cost, and dispersed structure of traditional control methods.

[0006] A state management interface for parallel battery cells provided by the present invention includes: A series-type regulating device has multiple voltage ports, which are connected in series with the power output side of the corresponding battery cell to form multiple parallel battery branches. The series-type regulating device is used to apply a controllable series compensation voltage to the branches. A bypass device, connected in parallel with the voltage port, is used to actively disconnect or isolate the series-type regulating device when a protection command is received. The circuit breaker is connected in series between the power output side of each battery cell and the external power interface. It is used to actively disconnect or isolate the corresponding battery cell when a protection command is received. The battery management system is communicatively connected to the battery cell, the series-type regulating device, the bypass device, and the circuit breaker device. The battery management system is used to monitor battery status information and issue control commands to each device according to the battery status information to achieve coordinated status regulation and fault isolation.

[0007] Preferably, the series-type regulating device is a discrete multi-port power converter, which consists of multiple independent power converter units, each of which is connected to the series voltage port of each parallel battery branch.

[0008] Preferably, the discrete multi-port power converter achieves energy interaction through any one or more combinations of common port capacitor connection, common DC bus connection, local energy exchange within branches, coupled energy transmission between branches, independent common energy storage capacitor, common energy transmission circuit, or independent power interface.

[0009] Preferably, the series-type regulating device is a multi-port power converter, which has multiple voltage ports and provides independent series voltage ports for each parallel battery branch, thereby realizing coordinated state regulation of the multiple parallel battery branches.

[0010] Preferably, the integrated multi-port power converter is configured with any one of the following structures: a common power port connected in series with the external power interface, a common power port connected in parallel with the common DC bus, an internal coupling structure without an external common power port, or an independent power interface.

[0011] Preferably, the interface supports three operating modes: equalization adjustment mode with the circuit breaker closed and the bypass device open, bypass through-through mode with the circuit breaker closed and the bypass device closed, and fault isolation mode with the circuit breaker open.

[0012] Preferably, the battery management system is configured to adopt a centralized collaborative control architecture to centrally acquire the operating status information of all parallel branches, calculate the global reference target, and centrally solve the power allocation weight of each branch based on the global reference target, so as to uniformly issue the control commands. Alternatively, it can be configured to adopt a distributed independent control architecture, in which the control part corresponding to each parallel branch acts as a distributed node, independently calculating and generating the control command based on the locally acquired operating status information and according to a preset adaptive adjustment rule.

[0013] According to the present invention, a parallel battery status management system includes multiple parallel battery units, a status management interface between the parallel battery units, a common DC bus, and a communication bus. Each battery cell is connected to a common DC bus after being aggregated through the aforementioned status control interface; The communication terminals of the multiple parallel battery units are connected to the control interface to provide the characteristic parameters of the battery units; The external communication interface of the control interface is connected to the communication bus and is configured to receive control commands issued by an external system via the communication bus, and based on the control commands and the operating status information of each battery cell determined internally, coordinately control the magnitude and direction of the power transmitted by the parallel battery system to the outside via the common DC bus.

[0014] A state management and control method for parallel battery cells according to the present invention, applied to the interface, is characterized by comprising the following steps: Real-time monitoring and acquisition of characteristic parameters of each battery cell, the characteristic parameters including at least voltage and current; Based on the aforementioned characteristic parameters, the operating status information of each battery cell is determined, and the operating status information includes at least the state of charge, overcurrent information, and overtemperature information of the battery cell. When the system is determined to be in normal operating condition, a voltage compensation command is generated based on the preset control architecture; and according to the voltage compensation command, the internal switching transistor of the series-type regulating device is switched to adjust the voltage value injected in series in the corresponding battery branch. When a fault is detected in one or more parallel branches, the abnormal parameters of the battery cell and series voltage port are monitored and the fault type and location are determined. If the series voltage port fails, the bypass device is closed. If the battery cell fails, the bypass device is closed first and then the circuit breaker is opened. The fault information is uploaded and the power distribution weight of the remaining healthy branches is reconstructed to maintain the continuity of the system's external output.

[0015] Preferably, by adjusting the voltage magnitude and polarity of the series voltage port, the control port provides power or absorbs power, decoupling the difference in open-circuit voltage and internal resistance of the battery cell, and realizing independent power allocation of each parallel branch.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention overcomes the voltage clamping limitations of traditional direct parallel architectures by connecting a multi-port power converter in series with the series voltage port of the battery cell's power output side. By controlling the magnitude and polarity of the series-injected voltage, the differences in internal resistance and open-circuit voltage between batteries can be offset, eliminating parallel circulating currents and enabling on-demand power distribution based on the battery cell's SOC and SOH. This breaks the "weakest link" effect in parallel systems and greatly improves the system's usable capacity and cycle life. 2. This invention integrates a bypass device and a circuit breaker. When a battery cell fails, the circuit breaker disconnects the battery while the bypass device maintains branch continuity. When the converter port fails, the bypass device short-circuits the port to directly connect the battery in parallel. This multi-level protection mechanism ensures that local faults are confined to a single branch, guaranteeing high continuity of power supply to the DC bus and the entire parallel system.

[0017] 3. The control architecture of this invention supports both centralized scheduling based on a global reference target and distributed control where nodes independently achieve power allocation through adaptive adjustment rules. This endows the system with scalability and plug-and-play capabilities, making it particularly suitable for scenarios involving mixed parallel operation of batteries from different batches and in different health states.

[0018] 4. Since the series-type regulating device of this invention only needs to process the part of the power used to compensate for voltage differences, rather than the full output power of the battery cell, the size, cost and heat loss of the power converter are reduced, and the overall conversion efficiency of the system is improved. Attached Figure Description

[0019] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the overall architecture of a parallel battery system provided in an embodiment of the present invention; Figure 2 This is an internal topology diagram of a single battery branch status management interface provided in an embodiment of the present invention; Figure 3a This is a diagram of the common port capacitor connection architecture of the discrete multi-port power converter provided in this embodiment of the invention; Figure 3b This is a diagram of the common DC bus connection architecture of the discrete multi-port power converter provided in this embodiment of the invention; Figure 3c This is a diagram of the local energy exchange architecture within a branch of a split multiport power converter provided in an embodiment of the present invention; Figure 3d This is a diagram of the inter-branch coupling energy transfer architecture of a split multi-port power converter provided in an embodiment of the present invention; Figure 3e This is a diagram of the independent common energy storage capacitor architecture of the discrete multi-port power converter provided in this embodiment of the invention; Figure 3f This is a common energy transmission loop architecture diagram of a discrete multi-port power converter provided in an embodiment of the present invention; Figure 3g This is an independent power interface architecture diagram of the discrete multi-port power converter provided in the embodiments of the present invention; Figure 4a This is a diagram of the common power port connection architecture of the integrated multi-port power converter connected in series with the external power interface trunk provided in this embodiment of the invention; Figure 4b This is a diagram showing the common power port connection architecture of the integrated multi-port power converter connected in parallel to a common DC bus, as provided in an embodiment of the present invention. Figure 4c This is a diagram of the internal coupling connection architecture of the integrated multi-port power converter without an external common power port provided in the embodiments of the present invention; Figure 4d This is a diagram of the integrated multi-port power converter with independent power interface connection provided in the embodiments of the present invention; Figure 5a This is a schematic diagram of the equivalent circuit of the parallel branch provided in the embodiment of the present invention and the terminal voltage of the battery cell in the discharge state with power flow greater than 0. Figure 5b This is a schematic diagram of the equivalent circuit of the parallel branch provided in the embodiment of the present invention and the terminal voltage of the battery cell in the discharge state with power flow being less than 0. Figure 5c This is a schematic diagram of the equivalent circuit of the parallel branch provided in the embodiment of the present invention and the terminal voltage of the battery cell in the charging state with power flow greater than 0. Figure 5d This is a schematic diagram of the equivalent circuit of the parallel branch provided in the embodiment of the present invention and the power flow in the charging state of the battery cell with a terminal voltage of less than 0. Figure 6 This is a control flowchart of the normal state management method provided in the embodiments of the present invention; Figure 7 This is a control flowchart of the fault protection and redistribution method provided in the embodiments of the present invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0021] This invention is connected to the power output side and information interface of each parallel battery unit, and has power interface and information interface to the outside world. Each battery unit can realize state adjustment, battery management, fault isolation and information interaction through the state control interface between the parallel battery units. The parallel battery cell inter-state control interface includes: a series-type regulating device, one voltage port of which is connected in series with the power output side of each battery cell. Through a certain regulating algorithm, the series-type regulating device adjusts the voltage value of the voltage port by switching the switching transistor, thereby achieving coordinated state regulation among the parallel battery cells; a bypass device, which is connected in parallel with the voltage port and, according to a certain control strategy, achieves fault isolation of each series-type regulating device; a circuit breaker device, which is installed between the power output side of each battery cell and the connection terminal of the external power interface, and, according to a certain control strategy, achieves fault isolation of each battery cell; and a battery management system, which monitors the voltage, current, temperature, and / or pressure information of each battery cell through the information interface of the battery cells, determines the operating status of the battery cells, and simultaneously achieves state regulation and fault isolation functions through the series-type regulating device, bypass device, and circuit breaker device.

[0022] Example 1 The parallel battery system provided by this invention aims to solve the problem of parallel mismatch caused by individual differences in battery cells. For example... Figure 1 As shown, the system includes multiple parallel battery cells, a status control interface 100 between the parallel battery cells, and a common DC bus. All battery cells are aggregated through the status control interface 100 to output their total power to the common DC bus, and also interact with external systems through this interface. The multiple battery cells include battery cell 1, battery cell 2, and so on, up to battery cell n, where n is a positive integer greater than or equal to 2.

[0023] It should be noted that the state management interface 100 between the parallel battery cells is the core of the technical solution of this application. For example... Figure 1 As shown, the interface 100 integrates multiple functional modules, which may include: a battery management system 101, a series regulating device 102, a bypass device 103, a circuit breaker device 104, and a unified control module 105.

[0024] The battery management system 101 exchanges data bidirectionally with the monitoring units, series regulating devices 102, bypass devices 103, circuit breaker devices 104, and unified control modules 105 within each battery cell via a communication bus (e.g., Controller Area Network bus, Ethernet, or other serial communication bus). In this embodiment, the main responsibility of the battery management system 101 is to collect and process the operating status information of each battery cell in real time. This information includes, but is not limited to, the battery cell's terminal voltage, charging and discharging current, internal temperature (obtainable from multiple temperature measurement points), voltage equalization status between cells, and cell pressure or stress information that may be included in some advanced applications. Based on the collected raw data, the battery management system 101 can use built-in algorithm models to estimate key operating status parameters of each battery cell, such as state of charge, state of health, and remaining available capacity. It is understood that these estimated status parameters constitute the basis for subsequent active equalization and fault diagnosis decisions. In addition, the battery management system 101 is also responsible for communicating with external systems (such as vehicle controllers and energy management systems of energy storage stations), reporting the status of the entire battery system, and receiving charging and discharging commands from higher-level systems.

[0025] Accordingly, the unified control module 105 can be considered as the execution unit of the battery management system 101. This module receives macro-control strategies and objectives from the battery management system 101 (e.g., ensuring all battery cells have a consistent state of charge, or distributing power proportionally according to their health status) and decomposes them into specific control instructions for the underlying hardware devices. The unified control module 105 directly controls the operation of the series regulator 102, the bypass device 103, and the circuit breaker 104. For example, based on calculations by the battery management system 101, this module can generate pulse-width modulation signals to drive the internal power switches of the series regulator 102 to produce the required compensation voltage; upon detecting a fault, it immediately issues instructions to close the corresponding bypass device 103 or open the circuit breaker 104. As an optional implementation, the functionality of the unified control module 105 can be integrated into the hardware of the battery management system 101, or it can exist as a separate microcontroller unit or digital signal processor.

[0026] The series-connected regulating device 102, bypass device 103, and circuit breaker 104 are the actuators for power regulation and fault isolation, and together they constitute the electrical interface of each battery branch. To better understand their structure and function, the following section combines... Figure 2 The internal topology of a single battery branch status control interface is described.

[0027] like Figure 2As shown, the power output terminals (positive or negative) of each battery cell are not directly connected in parallel, but are connected to a common DC bus through a series structure. Specifically, the current flows sequentially from the power output terminal of the battery cell through a series voltage port, a circuit breaker 104, and finally into the common DC bus. That is, in this embodiment, each battery cell forms a parallel branch, which includes at least: the battery cell, the series voltage port of the series-type regulating device 102 connected in series with the power output side of the battery cell, the bypass device 103 connected in parallel across the series voltage port, and the circuit breaker 104 connected in series between the branch and the external power interface.

[0028] The series voltage port is the core functional interface provided by the series-type regulating device 102 for each branch. The series-type regulating device 102 itself is a multi-port power electronic converter, providing n independent series voltage ports for n parallel branches in the system. Each port can be considered a controlled, bidirectional series voltage source, capable of injecting or absorbing a specific voltage into the branch according to the instructions of the unified control module 105, i.e., generating a compensation voltage. It is this compensation voltage that cancels out the voltage imbalance caused by the difference in open-circuit voltage and internal resistance of the battery cells, thereby achieving precise control of the current in that branch. The series-type regulating device 102 is used to apply a controllable series compensation voltage to each parallel branch.

[0029] The circuit breaker 104 is a switching device connected in series in the main power circuit. Under normal operation, it remains closed to allow current to flow. When the battery management system 101 and the unified control module 105 determine that a serious fault has occurred in a connected battery cell (such as an internal short circuit, thermal runaway risk, etc.), or when offline maintenance of the battery cell is required, the unified control module 105 issues a command to disconnect the circuit breaker 104. Disconnecting the circuit breaker 104 completely severs the electrical connection between the faulty branch and the entire parallel system, thereby isolating the fault within a single branch to ensure the safe operation of the remaining healthy branches and the entire system. The circuit breaker 104 can be implemented in various forms; for example, for high-current applications, it can be an electrically controlled DC contactor or circuit breaker; for low-current applications, it can be a solid-state relay or a solid-state switch composed of multiple power metal-oxide-semiconductor field-effect transistors.

[0030] The bypass device 103 is a switching device connected in parallel across the series voltage port, providing fault redundancy and operating mode switching capabilities. In normal active equalization regulation mode, the bypass device 103 remains open, allowing the series voltage port to operate normally. However, in two specific situations, the bypass device 103 will be closed: First, a port of the series regulator 102 malfunctions (e.g., an internal power device fails). In this case, closing the bypass device 103 short-circuits the faulty port, providing a low-impedance path for current. This allows the branch, although losing its active regulation capability, to continue operating in direct parallel, ensuring continuous power output. Second, in the process of fault isolation of the battery cell, the bypass device 103 is typically closed first, followed by the circuit breaker 104. This is done to provide a path for any potential inductive load freewheeling before disconnecting the circuit breaker 104, preventing dangerous arcing at the contacts of the circuit breaker 104. The bypass device 103 can also be implemented by a contactor, relay or solid-state switch.

[0031] Through the above structure, each parallel branch can flexibly operate in three modes under the control of the unified control module 105: 1. Balanced regulation mode: When the circuit breaker 104 is closed and the bypass device 103 is open, the series-type regulator 102 is put into operation, and its series voltage port and the battery unit jointly participate in the power transmission of the branch to perform branch power regulation and state balancing; 2. When the circuit breaker 104 is closed and the bypass device 103 is closed, the series voltage port is short-circuited, and the battery unit bypasses the series-type regulator 102 to directly participate in the power transmission of the common bus to reduce regulation link loss, or to maintain branch conduction when the series-type regulator 102 is abnormal; 3. Fault isolation mode: When the circuit breaker 104 is open, the branch is disconnected from the common bus, and the corresponding battery unit stops participating in external power transmission to achieve faulty branch isolation. This flexible switching capability of multiple modes provides a solid hardware foundation for achieving efficient and reliable parallel battery system management.

[0032] The state control interface 100 can serve as a unified interface layer between multiple parallel battery units and external systems, enabling multiple battery units to no longer be directly and rigidly connected in parallel. Instead, controllable series regulation capabilities are introduced into each branch, thereby achieving active decoupling, flexible regulation, and fault reconfiguration between parallel branches. Thus, by setting a series-type regulating device 102, a bypass device 103, and a circuit breaker 104 in each parallel battery branch, and combining this with the coordinated control of the battery management system 101 and the unified control module 105, active power distribution and state balancing can be achieved under normal operating conditions. Low-loss direct-through operation can be achieved when the regulating device malfunctions, and rapid branch disconnection can be achieved when a battery fails, thereby improving the reliability, fault tolerance, and power supply continuity of the entire parallel battery system.

[0033] Example 2 This embodiment will describe in detail the specific implementation of the series-type regulating device 102 described in Embodiment 1. As one of the core hardware components of the technical solution of this application, the performance and topology of the series-type regulating device 102 directly affect the system's regulation capability, efficiency, and cost. Based on the organization of its internal power conversion units, it can be mainly divided into two categories: discrete and integrated.

[0034] Figure 3 illustrates various connection architectures for a discrete multiport power converter. The discrete multiport power converter consists of multiple power converter units, including DC / DC 1, DC / DC 2, ..., DC / DC n, or composed of DC / DC units shared by some branches. Each power converter unit is connected to the series voltage port in the branch containing the corresponding battery unit to establish a controllable series compensation voltage in the corresponding branch, thereby adjusting the equivalent port characteristics of that branch. Each bypass device is connected in parallel across the corresponding series voltage port, and each circuit breaker is connected in series between the corresponding battery unit and the external power interface.

[0035] The status control interface is used to receive status information from each battery cell and control each power converter unit, bypass device and circuit breaker device to perform status adjustment, fault bypass and fault isolation.

[0036] For the common port capacitor connection method, please refer to [reference needed]. Figure 3aThe plurality of power converter units are connected to a common port capacitor on the common DC bus side. The common port capacitor is connected in series to either the positive or negative terminal of the common DC bus, and together with the common DC bus, forms an external power interface. One side of each power converter unit is connected to the series voltage port in its corresponding branch, and the other side is connected to the common port capacitor. In this embodiment, the power released from the series voltage port in any branch can be transmitted to the common port capacitor via the corresponding power converter unit, and absorbed and temporarily stored by the common port capacitor; conversely, when the series voltage port in any branch needs to absorb power, the common port capacitor can release energy to the corresponding power converter unit, which then supplies energy to the corresponding series voltage port.

[0037] For the common DC bus connection configuration, please refer to [reference needed]. Figure 3b The other side of each of the multiple power converter units is connected in parallel to a common DC bus, through which it interacts with the external power interface. One side of each power converter unit is connected to a series voltage port in its corresponding branch, and the other side is connected in parallel to the common DC bus. In this embodiment, the power released from the series voltage port in any branch can be directly transmitted to the common DC bus via the corresponding power converter unit; when the series voltage port in any branch needs to absorb power, energy can also be supplied to it from the common DC bus via the corresponding power converter unit.

[0038] For details on local energy exchange patterns within a branch, please refer to [reference needed]. Figure 3c In this parallel branch, the power converter units are respectively located within the corresponding branch and configured to form a local energy exchange channel between the series voltage port in that branch and the corresponding battery cell. In this embodiment, when the series voltage port in a branch needs to release power, the power can be provided by the corresponding battery cell; when the series voltage port in a branch needs to absorb power, the power can also be transmitted back to the corresponding battery cell. Thus, the compensation power is mainly completed within a closed loop within the branch.

[0039] For information on inter-branch coupling energy transfer patterns, please refer to [reference needed]. Figure 3d At least two parallel branches establish a power transmission channel through an inter-branch coupling network. Figure 3d The diagram illustrates a coupling configuration consisting of multiple cross-branch power converter units, such as DC / DC 1-2, DC / DC (k-1)-n, DC / DC n-1, etc. In this embodiment, the power absorbed by the series voltage port of the first branch can be transmitted to the second branch through the inter-branch power transmission channel, and absorbed by the series voltage port of the second branch and / or the corresponding battery cell of the second branch; conversely, the same applies, thereby achieving bidirectional energy regulation between branches.

[0040] For information on independent public energy storage capacitor configurations, please refer to [reference needed]. Figure 3e The series-type regulating device internally includes at least one common energy storage capacitor independent of the common DC bus. Multiple power converter units are connected to the series voltage ports in their respective branches, and together they form an energy exchange relationship with the common energy storage capacitor. In this embodiment, the power absorbed by the multiple series voltage ports can be collected and stored in the common energy storage capacitor; conversely, when the multiple series voltage ports need to release compensation power, the common energy storage capacitor can release energy uniformly, and the corresponding power converter units will then supply power to each series voltage port.

[0041] For information on common energy transmission loop configurations, please refer to [link / reference]. Figure 3f The series-type regulating device includes a common energy transmission loop, which is coupled to power converter units in multiple parallel branches. The series voltage ports in each branch are connected to this common energy transmission loop via their corresponding power converter units.

[0042] For independent power interface options, please refer to [link / reference]. Figure 3g At least one power converter unit is connected to an independent power supply interface, as illustrated in the diagram where multiple power converter units share a single independent power supply. In this embodiment, the power released from any series voltage port can be transmitted to the independent power supply interface via the corresponding power converter unit; conversely, when any series voltage port needs to absorb compensation power, the independent power supply interface can supply power to the corresponding power converter unit, which then transmits the power to the corresponding series voltage port.

[0043] Please refer to Figure 4, which illustrates different connection architectures of the integrated multiport power converter. The integrated multiport power converter has multiple series voltage ports, each connected to a corresponding parallel branch and connected in series with the power output side of the corresponding battery cell, to establish a controllable series compensation voltage in each branch.

[0044] Unlike the separate structure shown in Figure 3, in this embodiment, multiple series voltage ports are centrally implemented by the same multi-port DC / DC converter. Each bypass device is connected in parallel to the two ends of the corresponding series voltage port, and each circuit breaker is connected in series between the corresponding battery cell and the external power interface.

[0045] For the common power port connected in series with the external power interface trunk, please refer to... Figure 4a The integrated multi-port power converter has multiple series voltage ports corresponding to each parallel branch, and a common power port. The common power port is connected to a common port capacitor and together with a common DC bus, forms an external power interface.

[0046] For the common power port connected in parallel to the common DC bus, please refer to [reference needed]. Figure 4b The integrated multi-port power converter also has multiple series voltage ports and a common power port. The difference is that the common power port is connected in parallel to the two ends of a common DC bus or an external power interface.

[0047] For internal coupling configurations without an external common power port, please refer to [reference needed]. Figure 4c The integrated multiport power converter has multiple series voltage ports corresponding to each parallel branch, but no external common power port is provided. The series voltage ports are combined together through the internal structure of the integrated multiport power converter to directly transfer power between the parallel branches.

[0048] For those with an independent power interface, please refer to [the relevant documentation / reference]. Figure 4d The integrated multi-port power converter, in addition to having multiple series voltage ports corresponding to each parallel branch, also has an independent power interface. Each series voltage port interacts centrally with the independent power interface through the integrated multi-port power converter.

[0049] thus, Figures 4a to 4d The connection architectures shown correspond to different port organization methods of the integrated multi-port DC / DC converter, and can be selected or combined according to the system power level, control method, isolation requirements, energy coupling method and external auxiliary power supply configuration.

[0050] Through the above-mentioned various topologies, both separate and integrated, the series-type regulating device 102 of this application can be flexibly designed and selected according to specific application scenarios (such as power level, cost requirements, efficiency targets, space constraints, etc.), and has strong engineering practicality.

[0051] Example 3 This embodiment, in conjunction with Figure 5, will elaborate in detail on the power operation mechanism of the series voltage port in this application, that is, how to achieve precise adjustment of the branch power by controlling a series compensation voltage. Figure 5 is a schematic diagram of the equivalent circuit and power flow of the parallel branch.

[0052] For the power operation mechanism of the series voltage port, please refer to Figure 5. Figures 5a to 5d The different operating conditions of the series voltage port providing power or absorbing power during battery cell charging or discharging are shown respectively.

[0053] In a series circuit consisting of a battery cell and a series voltage port, the positive direction of the circuit current I is the discharge direction of the battery cell, and the voltage of the series voltage port is... The positive polarity is such that the potential drop along the positive direction of the circuit current is positive, and the terminal voltage of the battery cell is... .

[0054] The power of the series voltage port is then:

[0055] The power of the battery cell is:

[0056] Neglecting losses, the ratio of the power amplitude of the series voltage port to that of the battery cell satisfies:

[0057] Figure 5a : Discharge state and

[0058] At this time, the voltage of the series voltage port and the voltage of the battery cell are superimposed in the same direction, and the series voltage port provides power to the outside, thereby improving the equivalent output capability of the corresponding branch.

[0059] Figure 5b : Discharge state and

[0060] At this time, the voltage of the series voltage port is superimposed on the voltage of the battery cell in the opposite direction. The series voltage port absorbs power from the battery cell to receive at least part of the discharge power, thereby reducing the output capability of the corresponding branch.

[0061] Figure 5c Charging status and

[0062] At this time, the voltage of the series voltage port and the voltage of the battery cell are superimposed in the same direction, and the series voltage port absorbs power.

[0063] Figure 5d Charging status and

[0064] At this time, the voltage of the series voltage port is superimposed on the voltage of the battery cell in the opposite direction, and the series voltage port provides power to the battery cell to provide at least part of the charging power.

[0065] By controlling the voltage of the series voltage port The size and polarity of the series voltage port can selectively provide or absorb power under different operating conditions, thereby flexibly adjusting the port characteristics of the corresponding parallel branch and realizing power redistribution, state balancing and post-fault reconfiguration control in the parallel battery system.

[0066] Through the above four scenarios ( Figures 5a-5d As can be seen from the analysis, regardless of whether it is charging or discharging, by flexibly controlling the polarity and size of the series voltage port Uport, the technical solution of this application can completely decouple the individual differences of each battery cell, realize independent, precise and active control of the power flow of each branch, thereby breaking the barrel effect under the traditional parallel method and realizing the global optimal energy management.

[0067] Example 4 This embodiment will combine Figure 6 and Figure 7 This application provides a detailed description of the specific process of the state management method provided. The method includes active balancing control under normal operating conditions and fault protection and redistribution control under abnormal operating conditions.

[0068] First, please refer to Figure 6 This diagram shows the control flow of the normal state management method. This process is periodically executed by the battery management system 101 and the unified control module 105, and includes the following steps: S601: Real-time monitoring and acquisition of characteristic parameters of each battery cell. In this step, the system collects the physical parameters of each battery cell in real time through sensors, including but not limited to terminal voltage, current, temperature, and internal resistance, as the basis data for subsequent state assessment.

[0069] S602: Determine the operating status information of each battery cell. Based on the feature parameters obtained in step S601, calculate the real-time operating status information of each battery cell using a preset state estimation model, specifically including the state of charge (SOC), state of health (SOH), and the current available charge / discharge power limit.

[0070] In some implementations, the state estimation model may employ extended Kalman filtering, unscented Kalman filtering, sliding mode observer, or a data-driven state estimation algorithm. Subsequently, the system enters different control paths based on the currently employed control architecture.

[0071] If the system adopts a centralized collaborative control architecture, then execute steps S6031 and S6041: S6031: Centrally acquire the operating status information of all parallel branches, and calculate the global reference target in conjunction with the overall system bus requirements. The global reference target can be used to maintain the energy balance of the entire system, maximize capacity utilization, limit temperature rise operation, or optimize lifetime consistency.

[0072] S6041: Generate voltage compensation commands for each branch based on a global reference target. Based on the global reference target, the power allocation weights of each branch are solved by a centralized controller, and voltage compensation commands corresponding to each branch are uniformly generated and issued to achieve coordinated optimization and adjustment on a global scale.

[0073] If the system adopts a distributed independent control architecture, then execute steps S6032 and S6042: S6032: Obtain local operating status information for the corresponding battery cell. Each port controller obtains the operating status information of the corresponding battery cell through local sampling or point-to-point communication, without relying on global commands from the central controller.

[0074] S6042: Independently generate local voltage compensation commands. Each port controller independently calculates the local compensation benchmark according to preset adaptive adjustment rules and autonomously generates voltage compensation commands. The adaptive adjustment rules can be droop control strategies, virtual impedance control strategies, or other control strategies suitable for branch power redistribution.

[0075] S605: Controls the switching of internal switching transistors in the corresponding branch series-type regulating device. Upon receiving a voltage compensation command, regardless of whether the command is issued by the centralized controller or generated locally by the distributed controller, the drive circuit controls the power switching devices inside the series-type regulating device 102 to switch according to the set duty cycle.

[0076] In some embodiments, the power switching device may be a MOSFET, IGBT, SiC device, or GaN device.

[0077] S606: Adjusts the series-injected voltage to achieve power distribution and state balance. By controlling the switching transistor, an adjustable compensation voltage is dynamically injected into the branch, thereby changing the output voltage characteristics of the branch and achieving the purpose of regulating the branch current, realizing on-demand power distribution, and balancing the state of each battery cell.

[0078] Next, please refer to Figure 7 The diagram shows the control flow of the fault protection and redistribution method. This flow is an important guarantee for the safe and reliable operation of the system and includes the following steps: S701: Monitors abnormal characteristic parameters and generates abnormal information. The system's internal monitoring circuit compares operating parameters with preset safety thresholds in real time. When abnormal voltage fluctuations, current overloads, abnormal temperatures, abnormal pressures, abnormal insulation, or communication interruptions are detected, the system determines that a fault has occurred and generates abnormal information.

[0079] S702: Determine the fault type and location, and take corresponding isolation measures. If it is determined that the series voltage port is abnormal, such as a hardware failure of the regulating device, a drive abnormality, or a control failure, then execute step S7021 to control the bypass device 103 connected in parallel with the port to close, so that the faulty series voltage port is short-circuited to ensure that the branch current can still flow and avoid a single point fault causing the entire branch to fail.

[0080] If the battery cell is determined to be abnormal, such as a short circuit, overheating, insulation failure, or thermal runaway warning, then step S7022 is executed. First, the corresponding bypass device 103 is closed to protect the port circuit. Then, the corresponding circuit breaker 104 is activated to disconnect the faulty battery cell from the branch circuit, thereby achieving electrical isolation.

[0081] S703: Upload anomaly information. Encapsulate the fault location results, isolation action status, and affected branch information, and upload them in real time to the host computer, monitoring backend, or energy management system via CAN, RS485, industrial Ethernet, or other external communication interfaces so that maintenance personnel can receive alarms and perform subsequent processing.

[0082] S704: Readjust the power distribution weights of the remaining healthy branches. After the faulty branch is disconnected, the system dynamically adjusts the current sharing ratio or compensation weight of the healthy branches based on the operating status and carrying capacity of the remaining available branches, combined with external load demand or a preset derating operation algorithm.

[0083] S705: Maintains system output continuity. By adjusting the series compensation voltage of the remaining normal branches, its output power is increased or its absorbed power is adjusted to compensate for the power gap after the faulty unit is disconnected, thus maintaining the continuity of the system's external output voltage and power and achieving fault-tolerant operation under fault conditions.

[0084] By introducing a series-type regulating device 102, a bypass device 103, and a circuit breaker 104 into each parallel battery branch, and combining this with the coordinated control of the battery management system 101 and the unified control module 105, the present invention has at least the following beneficial effects: To achieve active and flexible adjustment between parallel branches, reduce bias current and circulating current, and improve the available capacity and consistency of the system; Achieve branch-level fault isolation to prevent a single branch fault from spreading to the entire parallel system; It supports bypass operation mode and can maintain low-loss conduction even when no adjustment is needed or the adjustment device is malfunctioning. It supports various multi-port power converter architectures, including discrete and integrated types, and has strong adaptability. It supports centralized or distributed control architectures, making it easy to choose the right model based on different system sizes and application requirements; It improves system reliability, fault tolerance, and power supply continuity, and is suitable for energy storage systems, power battery systems, and other parallel power supply systems.

[0085] This invention aims to achieve state control between battery cells by using a local series voltage regulation method, without having to bear the full power of charging and discharging of the battery cells; at the same time, it provides a unified external power and information port to realize unified internal and external management of the parallel battery system, and combined with bypass and circuit breaking devices, it provides an economical, efficient and reliable overall management and control solution for parallel batteries.

[0086] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A state control interface between parallel battery cells, characterized in that, include: A series-type regulating device has multiple voltage ports, which are connected in series with the power output side of the corresponding battery cell to form multiple parallel battery branches. The series-type regulating device is used to apply a controllable series compensation voltage to the branches. A bypass device, connected in parallel with the voltage port, is used to actively disconnect or isolate the series-type regulating device when a protection command is received. The circuit breaker is connected in series between the power output side of each battery cell and the external power interface. It is used to actively disconnect or isolate the corresponding battery cell when a protection command is received. The battery management system is communicatively connected to the battery cell, the series-type regulating device, the bypass device, and the circuit breaker device. The battery management system is used to monitor battery status information and issue control commands to each device according to the battery status information to achieve coordinated status regulation and fault isolation.

2. The state control interface between parallel battery cells according to claim 1, characterized in that, The series-type regulating device is a discrete multi-port power converter, which consists of multiple independent power converter units. Each power converter unit is connected to the series voltage port of each parallel battery branch.

3. The state control interface between parallel battery cells according to claim 2, characterized in that, The discrete multi-port power converter achieves energy interaction through any one or more combinations of the following: common port capacitor connection, common DC bus connection, local energy exchange within branches, coupled energy transmission between branches, independent common energy storage capacitor, common energy transmission circuit, or independent power interface.

4. The state control interface between parallel battery cells according to claim 1, characterized in that, The series-type regulating device is a multi-port power converter. The multi-port power converter has multiple voltage ports and provides independent series voltage ports for each parallel battery branch, thereby realizing coordinated state regulation of the multiple parallel battery branches.

5. The state control interface between parallel battery cells according to claim 4, characterized in that, The integrated multi-port power converter is configured with any one of the following structures: a common power port connected in series with the external power interface, a common power port connected in parallel with the common DC bus, an internal coupling structure without an external common power port, or an independent power interface.

6. The state control interface between parallel battery cells according to claim 1, characterized in that, The interface supports three operating modes: equalization mode with the circuit breaker closed and the bypass device open, bypass pass-through mode with the circuit breaker closed and the bypass device closed, and fault isolation mode with the circuit breaker open.

7. The state control interface between parallel battery cells according to claim 1, characterized in that, The battery management system is configured to adopt a centralized collaborative control architecture to centrally acquire the operating status information of all parallel branches, calculate the global reference target, and centrally solve the power allocation weight of each branch based on the global reference target, so as to uniformly issue the control commands. Alternatively, it can be configured to adopt a distributed independent control architecture, in which the control part corresponding to each parallel branch acts as a distributed node, independently calculating and generating the control command based on the locally acquired operating status information and according to a preset adaptive adjustment rule.

8. A parallel battery state management system, characterized in that, It includes multiple parallel battery cells, a state control interface between parallel battery cells as described in any one of claims 1-7, a common DC bus, and a communication bus; Each battery cell is connected to a common DC bus after being aggregated through the aforementioned status control interface; The communication terminals of the multiple parallel battery units are connected to the control interface to provide the characteristic parameters of the battery units; The external communication interface of the control interface is connected to the communication bus and is configured to receive control commands issued by an external system via the communication bus, and based on the control commands and the operating status information of each battery cell determined internally, coordinately control the magnitude and direction of the power transmitted by the parallel battery system to the outside via the common DC bus.

9. A method for managing and controlling the state of parallel battery cells, applied to the interface described in any one of claims 1-7, characterized in that, Includes the following steps: Real-time monitoring and acquisition of characteristic parameters of each battery cell, the characteristic parameters including at least voltage and current; Based on the aforementioned characteristic parameters, the operating status information of each battery cell is determined, and the operating status information includes at least the state of charge, overcurrent information, and overtemperature information of the battery cell. When the system is determined to be in normal operating condition, a voltage compensation command is generated based on the preset control architecture; and according to the voltage compensation command, the internal switching transistor of the series-type regulating device is switched to adjust the voltage value injected in series in the corresponding battery branch. When a fault is detected in one or more parallel branches, the abnormal parameters of the battery cell and series voltage port are monitored and the fault type and location are determined. If the series voltage port is faulty, the bypass device is closed. If the battery cell is faulty, the bypass device is closed first and then the circuit breaker is opened. Upload fault information and reconstruct the power allocation weights of the remaining healthy branches to maintain the continuity of the system's external output.

10. The method for managing and controlling the state of parallel battery cells according to claim 9, characterized in that, By adjusting the voltage magnitude and polarity of the series voltage port, the control port can provide or absorb power, decouple the open-circuit voltage and internal resistance differences of the battery cell, and realize independent power allocation of each parallel branch.

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