A bidirectional active equalization control timing method for battery management system

Abstract

This invention discloses a bidirectional active balancing control timing method for a battery management system, belonging to the field of battery management technology. The method includes: receiving a balancing command containing the target battery cell channel identifier and charge / discharge type; acquiring stored historical control parameters containing historical channel identifiers and historical parity attributes; comparing the current parameters with the historical parameters, and based on the comparison result, selectively controlling hardware switching actions: controlling the channel selection switch only when the channel identifier changes, and controlling the parity selection switch only when the parity attribute changes; finally, controlling the charge / discharge enable switch according to the charge / discharge type to initiate balancing, and updating the stored historical parameters. This invention effectively reduces redundant switching control operations by reusing historical control parameters, improving the response speed and execution efficiency of balancing control. Simultaneously, by integrating control verification and voltage diagnostic mechanisms, it enhances the reliability and safety of the system.

Description

Technical Field

[0001] This invention relates to a bidirectional active balancing control timing method for a battery management system, belonging to the field of battery management technology. Background Technology

[0002] Battery packs, consisting of multiple battery cells connected in series, are widely used in energy storage systems and electric vehicles. Due to differences in manufacturing processes, operating environments, and aging processes, the voltage, capacity, and other parameters of each individual battery cell can become inconsistent, resulting in decreased uniformity. This inconsistency reduces the usable capacity of the battery pack, shortens its lifespan, and can even pose safety hazards. Therefore, the balancing function in a battery management system is crucial; its purpose is to achieve a more uniform state of charge (SOC) among the individual battery cells through energy transfer.

[0003] Active balancing technology has become a research hotspot due to its high efficiency and relatively low energy loss. Among them, bidirectional active balancing circuits can perform bidirectional energy transfer between individual battery cells as needed. However, in actual control processes, to achieve connection with specific cells and determine energy flow direction, the battery management system needs to control multiple hardware switches. Existing technologies, when performing balancing control, typically reconfigure all relevant switches according to a fixed process each time a balancing command is received, regardless of the current state. This redundant operation leads to the following problems: frequent switching actions may affect device lifespan; the complete command issuance, hardware response, and stabilization waiting process results in slow overall system response speed and low effective duty cycle for balancing; redundant control logic consumes a significant amount of controller processing time and resources. Therefore, there is an urgent need for a bidirectional active balancing control timing method that can reduce redundant operations, improve control efficiency and system response speed, while ensuring control reliability. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a bidirectional active balancing control timing method for battery management systems, which overcomes the shortcomings of existing bidirectional active balancing control, such as redundant operation, low efficiency, and slow response.

[0005] The technical solution adopted by this invention to solve its technical problem is: A bidirectional active balancing control timing method for a battery management system includes the following steps: Receive active balancing control instructions, the instructions indicating at least the channel identifier and charge / discharge type of the target battery cell; Obtain the stored historical control parameters, which include at least the historical channel identifier and historical parity attribute involved in the last equalization operation; The current channel identifier is compared with the historical channel identifier, and the parity attribute determined based on the current channel identifier is compared with the historical parity attribute; Based on the comparison results, selectively control the hardware switching action: If the current channel identifier is different from the historical channel identifier, the channel selection switch is activated to select the target battery cell. If the current parity attribute is inconsistent with the historical parity attribute, then control the parity gating switch action; Based on the charge / discharge type, control the charge / discharge enable switch to activate equalization; The channel identifier and parity attribute update will be stored as new historical control parameters.

[0006] Preferably, after the equalization is initiated, a diagnostic step is further included, specifically including: Real-time acquisition of the voltage at the diagnostic points in the bidirectional active equalization circuit; Determine whether the voltage is within a preset safety range corresponding to the current operating state; If the voltage exceeds the preset safety range, the charge / discharge enable switch will be immediately turned off and a fault information will be reported.

[0007] Preferably, after controlling any of the hardware switches, a verification and recovery step is further included, specifically including: Read back the actual state of the hardware switch and compare it with the expected instruction state; If there is a discrepancy, it is determined to be a control failure, and a recovery process is executed. The recovery process includes: resetting the failure switch to the default state and re-controlling it; if the cumulative number of failures reaches a threshold, a system fault is reported.

[0008] Preferably, upon receiving a command to disable load balancing, the following actions are performed: Turn off the charge / discharge enable switch; The current states of the channel selection switch and the odd / even selection switch remain unchanged.

[0009] Preferably, when the battery management system enters sleep mode or fault protection mode, the following is executed: Turn off all equalization enable signals; Clear all stored historical control parameters.

[0010] Preferably, the operation of the hardware switch follows a defined timing logic, wherein: The operation of the charge / discharge enable switch is performed after the states of the channel selection switch and the odd / even selection switch have stabilized. The pulse width of both the channel selection switch and the odd / even selection switch is not less than 1 millisecond.

[0011] Preferably, the method for classifying the odd / even attribute is as follows: The cells with odd physical location numbers in the battery string are divided into odd groups, which are controlled by the first control line; Individuals with even-numbered physical location numbers are divided into even-numbered groups, which are controlled by the second control line.

[0012] The present invention also provides a battery management device, comprising: The control command receiving module is used to receive active equalization control commands; The storage module is used to store historical control parameters; The control logic module is used to execute the bidirectional active balancing control timing method for the battery management system and output a switching control signal. A switch driving circuit is used to respond to the switch control signal and drive the corresponding hardware switch to operate.

[0013] The present invention also provides a battery management system, characterized in that it includes the battery management device as described in claim 8, and a battery module and a bidirectional active power balancing circuit electrically connected to the device.

[0014] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the bidirectional active equalization control timing method for a battery management system.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: By comparing and reusing historical control parameters, redundant control command issuance and hardware switching actions are effectively reduced, thereby reducing the controller's processing burden and timing wait time, which significantly improves the execution efficiency and overall response performance of active balancing control. It integrates control verification and automatic recovery mechanisms, which can automatically attempt recovery when control fails and actively report after multiple failures, thus avoiding system function failure caused by occasional control anomalies. By sampling the voltage at the diagnostic points in the hardware circuit, the circuit status can be monitored in real time during the equalization process. Once an abnormal voltage is detected, protection is automatically implemented to ensure system safety. When the system enters hibernation or protection mode, historical control parameters are automatically cleared, which avoids erroneous operations caused by data residue in the new wake-up cycle and improves the rigor of system status management. It reduces unnecessary communication and computation, allowing the battery management system's main controller to free up more resources for other critical tasks, making it particularly suitable for complex battery management scenarios with high integration and multiple channels. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 A flowchart of a bidirectional active equalization control timing method provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the active balancing diagnostic process in one embodiment of the present invention; Figure 3 This is a schematic diagram of the switch control state verification and recovery process in one embodiment of the present invention; Figure 4 This is a structural block diagram of a battery management device provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of a battery management system provided in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The bidirectional active balancing control timing method for battery management systems provided by this invention is executed by a microcontroller unit in the battery management system and is applicable to battery management systems containing a bidirectional active balancing power topology. A common implementation of the bidirectional active balancing power circuit includes energy storage and transfer elements and multiple controlled switches.

[0020] Specifically, this circuit section includes an inductor L1 as an energy transfer element, which is connected to the battery cell via a switching network. ) and equalization bus connection. Switching networks mainly include three types of switches: Multiple channel gating switches, wherein the channel gating switches include , ... are used to connect the equalization circuit to a specific battery cell; The odd / even selection switches are respectively , This is used to connect the common path of either odd-numbered or even-numbered battery packs. And the charge / discharge enable switch, specifically, the charge / discharge enable switch can consist of four switching transistors. , , , Composition A bridge circuit is used, with its input connected to the equalization bus and its output connected to the selected battery cell path. This is achieved through control... By controlling the conduction of different diagonal switching transistors in the bridge, the energy flow direction can be controlled; that is, when the control... and When the circuit is turned on, energy flows from the equalization bus to the individual battery cells; control and When the circuit is turned on, energy flows from the individual battery cells to the equalization bus. A diagnostic point is also included in the circuit. It is used to sample the voltage of key nodes to monitor the circuit status.

[0021] like Figure 1 As shown, this embodiment provides a bidirectional active balancing control timing method for a battery management system, the steps of which include: The upper-level balancing decision algorithm of the battery management system determines that a specific battery cell needs to be balanced and generates a control command for issuance. This command includes at least a target channel identifier and a charge / discharge type. The target channel identifier uniquely corresponds to a single cell in the battery module, and the charge / discharge type indicates whether the current balancing operation is charging or discharging that cell.

[0022] The historical control parameters stored after the last successful equalization operation are read from the memory, including at least the historical channel identifier and historical parity attribute. The parity attribute is an identifier determined based on the channel identifier, used to indicate whether the target battery cell belongs to an odd or even group. In this embodiment, all cells with odd physical location numbers in the battery string are divided into an odd group, which is controlled by a separate control line; cells with even numbers are divided into an even group, which is controlled by another control line. Therefore, for a given channel identifier, its parity attribute can be determined by calculation, with a result of 1 indicating an odd number and a result of 0 indicating an even number.

[0023] It should be noted that the parity attribute is a logical group identifier. In terms of hardware, there are master switches for odd and even groups, used to control the corresponding power supply or signal path when switching between parity and even groups; each battery cell still has an independent channel selector switch controlling its connection to the equalization circuit. When it is necessary to select a particular cell, both its group master switch and its own channel selector switch must be closed simultaneously.

[0024] The received channel identifier is compared with the stored historical channel identifiers for numerical equality. Simultaneously, the parity attribute calculated based on the current channel identifier is compared with the stored historical parity attributes.

[0025] The controller determines which hardware switches need to be activated based on the comparison results: If the current channel identifier is different from the historical channel identifier, it indicates that the target cell has changed. In this case, a control signal is generated to drive the corresponding channel selection switch to switch the equalization power circuit to the physical channel where the target battery cell is located. If the two are equal, the channel selection control step is skipped.

[0026] If the current parity attribute is not equal to the historical parity attribute, it indicates that the parity group of the target unit has changed. In this case, the parity selection switch is activated to connect the corresponding odd or even group control line. If the two are equal, this step is skipped.

[0027] The charge / discharge enable control does not rely on historical parameters; it executes directly based on the charge / discharge type in the command. The controller operates the charge / discharge enable switch, configuring it to either charging or discharging mode, and finally closes the main enable switch to initiate the energy transfer process.

[0028] To ensure reliable switch control, after issuing a switch control command and waiting for a stable delay, the controller reads back the actual level state of the critical switch nodes through its input / output interfaces. The read-back actual state is compared bit by bit with the expected command state. If all bits match, the control is considered successful. If any inconsistency is found, the control is considered a failure.

[0029] Specifically, such as Figure 3 The diagram shown illustrates the switch control state verification and recovery process in one embodiment of the present invention. The controller immediately executes the recovery process, which specifically includes: Reset all relevant switch control signals to a safe default state, which means that all channel gating switches, odd / even gating switches, and charge / discharge enable switches are off. The control flow is retried, and the controller has an internal failure counter. If the verification fails again after the retry, the counter is incremented. When the cumulative number of failures reaches a preset threshold, the controller determines that there is a hardware fault, stops attempting, and reports the switch control hardware fault information to the upper-level system.

[0030] After the charge / discharge enable switch is closed and the equalization process officially begins, the controller initiates a background diagnostic task. This task periodically collects the voltage at preset diagnostic points in the bidirectional active equalization power circuit.

[0031] Diagnostic points It can be set at the primary side of the DC-DC converter to indicate whether the power circuit is conducting normally. The controller determines the corresponding preset safe voltage range based on the current charging / discharging type and parity.

[0032] Furthermore, the preset safety range is a voltage threshold range determined jointly by the current equalization direction and the odd / even group identifier. Specifically, in this embodiment, when the hardware circuit is working normally, in order to cover different operating conditions in actual applications, tests are conducted under various individual unit voltages and power supply voltages for four operating states: odd-array charging, odd-array discharging, even-array charging, and even-array discharging. The voltage values ​​at the diagnostic points are obtained, and the average value of the test values ​​plus or minus 20% is taken as the preset safety range for the corresponding state, denoted as... The collected diagnostic point voltages are accumulated, equalized, filtered, and recorded as follows: During diagnosis, direct judgment If the voltage is outside the preset safe range [Vmin, Vmax] corresponding to the current state, the controller will immediately force the charge / discharge enable switch to shut down, stop balancing, and report fault information including fault code and specific voltage value.

[0033] Once the current equalization control command is successfully executed and passes the initial verification, the controller writes the channel identifier and parity attribute used in this operation into the storage area, overwriting the old historical parameters, and uses this as the historical reference benchmark for the next equalization control.

[0034] For the command to disable equalization, the controller only performs the operation of disabling the charge / discharge enable switch, while keeping the states of the channel selection switch and the odd / even selection switch unchanged.

[0035] When the battery management system enters hibernation mode or high-level fault protection mode due to power failure or malfunction of the energy storage system, the controller will actively clear the historical control parameters stored in the volatile memory after completing the necessary safety shutdown procedures.

[0036] Example 1

[0037] like Figure 2 As shown, in this embodiment, a battery management system manages a 16-cell lithium battery pack, and its bidirectional active balancing circuit adopts the aforementioned topology. Upon initial power-up of the microcontroller unit, the historical parameter storage area is empty, and the operation process specifically includes: Initial equalization, i.e., discharge of cell 5: Receive instruction: Channel identifier = 5, type = discharge.

[0038] Get historical parameters: historical channel identifier = 0, historical parity attribute = 0.

[0039] Comparison: 5 is not equal to 0; the parity attribute is not equal to 0 this time.

[0040] Control actions: First, control the channel selection switch to connect channel 5, then control the odd-even selection switch to connect the odd group control lines, and finally control the charge / discharge enable switch to configure the discharge mode and start the process.

[0041] Update history: History channel identifier = 5, History parity attribute = odd.

[0042] The second equilibration process involves charging cell 6: Receive instruction: Channel identifier = 6, Type = Charging.

[0043] Get historical parameters: historical channel identifier = 5, historical parity attribute = odd.

[0044] Comparison: 6 is not equal to 5; the parity attribute is not equal to odd in this case.

[0045] Control actions: First, control the channel selection switch to connect channel 6, then control the odd-even selection switch to switch to the even group control line, and finally control the charge / discharge enable switch to configure the charging mode and start the charging process.

[0046] Update history: History channel identifier = 6, History parity = even.

[0047] The third equalization, i.e., discharging cell 6 again: Receive instruction: Channel identifier = 6, Type = Discharge.

[0048] Get historical parameters: historical channel identifier = 6, historical parity attribute = even.

[0049] Comparison: 6 equals 6; the parity attribute is even this time.

[0050] Control action: Skip channel selection and odd / even selection control, only control the charge / discharge enable switch to switch from charging mode to discharging mode and start it. This operation saves two switching actions and their stabilization waiting time.

[0051] Update history: History channel identifier = 6, History parity = even.

[0052] Example 2

[0053] In this embodiment, under the same hardware platform and balancing strategy, both the traditional full-instruction control timing and the intelligent multiplexing timing of the present invention were run for 24 hours each to simulate frequent balancing demands. Statistical results show that, after adopting the timing of the present invention, the average response time of a single balancing command is reduced by approximately 48% (percentage), the effective duty cycle of the balancing power loop can be increased from approximately 85% of the traditional timing to approximately 94%, the number of executions of switch control-related instructions is reduced by approximately 41%, and the CPU load of the microcontroller unit used for balancing control is also significantly reduced. Experimental results demonstrate that the present invention significantly improves system response speed and balancing efficiency by reducing redundant switch control, while simultaneously reducing controller load.

[0054] Example 3

[0055] In this embodiment, an alternative implementation is provided, which does not require strict parity grouping. In actual operation, multiple channels can be divided into multiple groups, each group containing several adjacent channels, controlled by a group selection switch.

[0056] At this point, the concept of parity can be replaced by group attributes. Historical channel identifiers and historical group identifiers are stored in the historical control parameters. The control logic changes to: comparing channel identifiers to determine whether to switch channels; comparing group identifiers to determine whether to switch group selection switches. The core idea is to avoid redundant operations by comparing historical control parameters, which is consistent with the core idea of ​​this invention and also achieves the effect of improving efficiency.

[0057] Example 4

[0058] In this embodiment, as Figure 4 As shown, a battery management device for implementing the above method is provided. The device includes: Control command receiving module: This is usually the communication interface of the microcontroller unit, used to receive equalization commands from the main controller of the battery management system.

[0059] Storage module: Used to persistently store historical channel identifiers and historical parity attributes.

[0060] Control logic module: Implemented by the microcontroller unit kernel and its firmware, it is used to execute the above method flow, perform parameter comparison, logic judgment, and generate corresponding digital switch control signals.

[0061] Switch drive circuit: Receives digital signals from the control logic module, performs level conversion and power amplification, and drives external channel selection switches, odd / even selection switches, and charge / discharge enable switches.

[0062] Example 5

[0063] like Figure 5As shown, this embodiment provides a battery management system including the aforementioned battery management device. The system includes: Battery module: Composed of multiple battery cells connected in series.

[0064] Bidirectional active equalization power circuit: It includes energy storage and transfer elements as well as various switches driven by battery management devices, forming a complete bidirectional energy transfer path.

[0065] Battery management device: connected to the sampling line and equalization line of the battery module, and connected to the control terminal of the power circuit.

[0066] Battery Management System Main Controller: Responsible for monitoring total voltage, total current, and temperature, executing equalization decision algorithms, and issuing control commands to the battery management device.

[0067] This system achieves fast, reliable, and efficient proactive balancing management of battery modules through efficient control timing implemented by the battery management device.

[0068] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A bidirectional active balancing control timing method for a battery management system, characterized in that, Includes the following steps: Receive active balancing control instructions, the instructions indicating at least the channel identifier and charge / discharge type of the target battery cell; Obtain the stored historical control parameters, which include at least the historical channel identifier and historical parity attribute involved in the last equalization operation; The current channel identifier is compared with the historical channel identifier, and the parity attribute determined based on the current channel identifier is compared with the historical parity attribute; Based on the comparison results, selectively control the hardware switching action: If the current channel identifier is different from the historical channel identifier, the channel selection switch is activated to select the target battery cell. If the current parity attribute is inconsistent with the historical parity attribute, then control the parity gating switch action; Based on the charge / discharge type, control the charge / discharge enable switch to activate equalization; The channel identifier and parity attribute update will be stored as new historical control parameters.

2. The bidirectional active balancing control timing method for a battery management system according to claim 1, characterized in that, Following the start-up of equalization, a diagnostic step is also included, specifically: Real-time acquisition of the voltage at the diagnostic points in the bidirectional active equalization circuit; Determine whether the voltage is within a preset safety range corresponding to the current operating state; If the voltage exceeds the preset safety range, the charge / discharge enable switch will be immediately turned off and a fault information will be reported.

3. The bidirectional active balancing control timing method for a battery management system according to claim 1, characterized in that, After controlling any of the aforementioned hardware switches, a verification and recovery step is also included, specifically including: Read back the actual state of the hardware switch and compare it with the expected instruction state; If there is a discrepancy, it is determined to be a control failure, and a recovery process is executed. The recovery process includes: resetting the failure switch to the default state and re-controlling it; if the cumulative number of failures reaches a threshold, a system fault is reported.

4. The bidirectional active balancing control timing method for a battery management system according to claim 1, characterized in that, Upon receiving a command to disable load balancing, execute: Turn off the charge / discharge enable switch; The current states of the channel selection switch and the odd / even selection switch remain unchanged.

5. A bidirectional active balancing control timing method for a battery management system according to claim 4, characterized in that, When the battery management system enters sleep mode or fault protection mode, the following is executed: Turn off all equalization enable signals; Clear all stored historical control parameters.

6. The bidirectional active balancing control timing method for a battery management system according to claim 1, characterized in that, The operation of the hardware switch follows a defined timing logic, wherein: The operation of the charge / discharge enable switch is performed after the states of the channel selection switch and the odd / even selection switch have stabilized. The pulse width of both the channel selection switch and the odd / even selection switch is not less than 1 millisecond.

7. The bidirectional active balancing control timing method for a battery management system according to claim 1, characterized in that, The method for classifying the odd / even attribute is as follows: The cells with odd physical location numbers in the battery string are divided into odd groups, which are controlled by the first control line; Individuals with even-numbered physical location numbers are divided into even-numbered groups, which are controlled by the second control line.

8. A battery management device, characterized in that, include: The control command receiving module is used to receive active equalization control commands; The storage module is used to store historical control parameters; The control logic module is used to execute the bidirectional active balancing control timing method for a battery management system as described in any one of claims 1 to 7, and to output a switching control signal; A switch driving circuit is used to respond to the switch control signal and drive the corresponding hardware switch to operate.

9. A battery management system, characterized in that, It includes the battery management device as described in claim 8, as well as a battery module and a bidirectional active power balancing circuit electrically connected to the device.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the bidirectional active balancing control timing method for a battery management system as described in any one of claims 1 to 7.

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