Battery pack parallel anti-recharge control method

Abstract

This invention relates to the field of lithium battery module and battery pack management technology, specifically to a parallel reverse charging control method for battery packs. The method uses a key-activated wake-up and communication identification system to determine the operating mode, combined with a progressive conduction control and current threshold delay confirmation mechanism for charging and discharging MOSFETs. In discharge mode, the charging MOSFET is prioritized for activation, and the body diode of the charging MOSFET is used to block reverse circulating current. In charging mode, the charging MOSFET is prioritized for activation, and the body diode of the discharging MOSFET is used to block forward circulating current. Only after the current stabilizes is the other MOSFET activated. This achieves physical isolation of the circulating current path and effective suppression of inrush current in multi-battery-pack parallel scenarios. It addresses the key problems of traditional P-topology with cement resistors, such as bulky size, high heat generation, and high cost, as well as the high communication synchronization requirements, brief conduction impact of body diodes, and logic disorder and loss of control caused by P+topology pre-charge enable control strategies.

Description

Technical Field

[0001] This invention relates to the field of lithium battery module and battery pack management technology, and more specifically, to a method for parallel anti-reverse charging control of battery packs. Background Technology

[0002] In the field of lithium battery modules and battery pack management, parallel expansion of multiple battery packs is a key technology for improving system power density and energy capacity. Achieving current sharing and suppressing circulating current among parallel battery packs is a fundamental prerequisite for ensuring the long lifespan and high safety of lithium battery modules.

[0003] However, in practical applications, when multiple battery packs are directly connected in parallel due to inconsistencies in initial voltage, internal resistance, or state of charge (SOC), a low-impedance loop current is easily formed, generating a very large instantaneous inrush current. This may not only trigger hardware overcurrent protection, but in severe cases, it may even cause thermal runaway or internal short circuits in the battery cells due to large-current mutual charging, damaging the battery cells.

[0004] To address the above problems, existing technologies mainly employ two approaches:

[0005] One approach is to use a pre-charge current limiting scheme with a P-disconnect topology and a cement resistor. This scheme suppresses the inrush current during grid connection by connecting a cement resistor in series with the negative terminal of the battery pack. However, this method is a passive energy-dissipating protection, which has drawbacks such as large size, high heat generation, and high energy consumption. Furthermore, the fixed resistance value is difficult to adapt to different differential pressure conditions, and it cannot effectively avoid the risk of circulating current.

[0006] Secondly, a pre-charge enable control strategy using a P+ disconnect topology is employed. This scheme only turns on the charging MOS (utilizing the unidirectional conductivity of the body diode) during grid connection, and then turns on the discharging MOS after the current stabilizes. However, this scheme has high requirements for the matching of current threshold and delay time. In scenarios with large voltage difference parallel connections, the brief conduction of the body diode can still introduce instantaneous impacts. At the same time, the synchronization requirements for multi-packet communication are extremely high. Once the control is deviated, it can easily lead to logic disorder and threaten system safety.

[0007] In summary, existing parallel protection technologies for lithium battery modules generally suffer from problems such as delayed protection action, high hardware costs, and large size when dealing with multiple battery packs operating in parallel, making it difficult to achieve accurate suppression of inrush current under the premise of low cost and small size. Summary of the Invention

[0008] The purpose of this invention is to overcome the key defects of existing lithium battery module parallel protection technology when dealing with multiple battery packs in parallel operation. These defects include delayed protection action, slow dynamic response, high hardware cost, bulky system size, failure to suppress instantaneous inrush current, inability to completely cut off the circulating current path, disordered communication synchronization of multiple packs, and even system loss of control.

[0009] The purpose of this invention is to provide a battery pack parallel anti-reverse charging control method. By using key wake-up and communication identification to determine the system's working mode, combined with the progressive conduction control of charging and discharging MOSFETs and the current threshold delay confirmation mechanism, the method prioritizes the opening of the charging MOSFET in discharge mode and uses the body diode of the charging MOSFET to isolate the loop current path. In charging mode, the method prioritizes the opening of the charging MOSFET and uses the body diode of the discharging MOSFET to isolate the loop current path. After the current stabilizes, the other MOSFET is then turned on. This achieves physical isolation of the circulating current path and suppression of inrush current in multi-battery pack parallel scenarios. This solves the key defects of traditional P-topology with cement resistor solution, such as bulky size, high heat generation, high energy consumption, and high cost, as well as the high communication synchronization requirements, brief conduction impact of body diode, and logic disorder and loss of control caused by P+topology pre-charge enable control strategy.

[0010] To achieve the above objectives, the present invention aims to provide a method for controlling reverse charging of a battery pack in parallel, comprising the following steps:

[0011] Step S1: Construct a multi-battery pack working mode discrimination platform based on key wake-up and communication recognition, and use key signals and communication commands to jointly determine whether the current system is in discharge mode or charging mode;

[0012] Step S2: When the system is determined to enter the discharge mode, the progressive conduction control of the MOSFET in the discharge mode is executed. The discharge MOSFET is turned on first, and the body diode of the charging MOSFET is used to isolate the loop current path. After the discharge current is detected to reach the preset threshold and remain stable, the charging MOSFET is turned on.

[0013] Step S3: When the system is determined to enter the charging mode, the differential conduction control of the MOSFET in the charging mode is executed. The charging MOSFET is turned on first, the body diode of the discharging MOSFET is used to isolate the loop current path, and the discharging MOSFET is turned on after the charging current reaches the preset threshold and remains stable.

[0014] Step S4: In the scenario of multiple battery packs in parallel, each battery pack independently executes the control logic of step S2 or step S3 above, and the physical isolation of the circulating current path is achieved through the body diode of the charging MOSFET or discharging MOSFET of each battery pack, thereby suppressing the mutual charging current between the packs.

[0015] Step S5: When the key signal is detected to be off or a shutdown command is received, execute the full shutdown control of the MOSFET, and simultaneously shut down the charging MOSFET and the discharging MOSFET, so that the battery pack is completely disconnected from the external circuit.

[0016] As a further improvement to this technical solution, in step S1, the microcontroller monitors the key signal Car_Key and the communication commands TX0 / RX0 in real time.

[0017] If a valid key signal is detected, the system is determined to enter the discharge mode;

[0018] If no key signal is detected but a charging command is received from the control board, the system is determined to enter charging mode.

[0019] As a further improvement to this technical solution, the progressive turn-on control of the MOS transistor in the discharge mode in step S2 specifically includes:

[0020] The microcontroller first turns on the discharge MOSFET, while the charging MOSFET remains off. The battery pack forms a discharge circuit through the channel of the discharge MOSFET and the body diode of the charging MOSFET.

[0021] The discharge circuit current value I is sampled in real time and compared with the preset current threshold Ith;

[0022] If I < Ith, then maintain the current state and keep the charging MOSFET off;

[0023] If I≥Ith, then the timer is started to perform a delay judgment. If the current remains above the threshold within the set delay time Td, then the charging MOSFET is turned on, so that all charging and discharging MOSFETs are turned on.

[0024] As a further improvement to this technical solution, the differentiated conduction control of the MOS transistor in the charging mode in step S3 specifically includes:

[0025] The microcontroller first turns on the charging MOSFET, while the discharging MOSFET remains off. The charger charges the battery pack through the channel of the charging MOSFET and the body diode of the discharging MOSFET.

[0026] The charging circuit current value I is sampled in real time and compared with the preset current threshold Ith;

[0027] If I < Ith, then maintain the current state and keep the discharge MOSFET off;

[0028] If I≥Ith, then the timer is started to perform a delay judgment. If the current remains above the threshold within the set delay time Td, then the discharge MOSFET is turned on, so that all the charging and discharging MOSFETs are turned on.

[0029] As a further improvement to this technical solution, in step S4, in the parallel discharge scenario, multiple battery packs simultaneously receive discharge commands from the main control board, and each battery pack independently executes the control logic of step S2. They all first turn on the power MOS and keep the charging MOS off. The P- terminals of each battery pack are isolated from each other through the body diode of the charging MOS. Only when the discharge current of a certain battery pack reaches the threshold and remains stable will its charging MOS be turned on.

[0030] As a further improvement to this technical solution, in step S4, in the parallel charging scenario, multiple battery packs simultaneously receive charging commands from the main control board, and each battery pack independently executes the control logic of step S3, first turning on the charging MOS and keeping the discharging MOS off. The battery packs are isolated from each other by the body diode of the discharging MOS. Only when the charging current of a certain battery pack reaches the threshold and remains stable will its discharging MOS be turned on.

[0031] As a further improvement to this technical solution, in step S5, when the key signal is detected to be off or a shutdown command is received from the main control board, the microcontroller immediately shuts down the charging MOSFET and the discharging MOSFET simultaneously, so that the battery pack enters standby or hibernation state.

[0032] As a further improvement to this technical solution, the preset current threshold Ith is 2A, and the preset delay time Td is 2 seconds; the current threshold and delay time are fixed values ​​or adjustable parameters preset according to the battery pack characteristics and system requirements.

[0033] As a further improvement to this technical solution, the method is implemented using the current sampling module and timer resources built into the microcontroller, without the need to add cement resistors, pre-charge relays or external detection circuits.

[0034] In this invention, a multi-battery pack operating mode discrimination platform is first constructed using a key wake-up signal and communication commands to accurately identify and logically separate whether the system is in discharge or charging mode. Then, based on the mode discrimination result, differentiated progressive MOSFET turn-on control is executed—in discharge mode, the discharge MOSFET is turned on first, utilizing the body diode of the charging MOSFET to naturally block the reverse circulation path; in charging mode, the charging MOSFET is turned on first, utilizing the body diode of the discharge MOSFET to naturally block the forward circulation path, and real-time current sampling and threshold comparison are introduced simultaneously. When the detected current reaches a preset threshold and remains stable for a specified delay time, the other MOSFET is then turned on. The S-tube short-circuits the body diode, achieving a highly efficient and seamless switching from single-tube isolated conduction to dual-tube full conduction. In multi-pack parallel scenarios, each battery pack independently executes the above control logic, completely cutting off the inter-pack circulating current path through the physical isolation characteristics of the body diodes of each pack. At the same time, after the current stabilizes, it autonomously completes the dual-tube full-on operation, effectively suppressing the inrush mutual charging current caused by voltage differences. Ultimately, without increasing any hardware costs, relying on multi-pack communication synchronization, or occupying additional PCB space, it completes the entire process control from working mode recognition to circulating current path isolation to efficient and stable output, significantly improving the safety and reliability of lithium battery modules in multi-pack parallel application scenarios.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] In this parallel anti-reverse charging control method for battery packs, a working mode discrimination platform based on key wake-up and communication identification is constructed. Combined with the progressive conduction control of charging and discharging MOSFETs and the current threshold delay confirmation mechanism, the physical isolation of the circulating current path and the effective suppression of the inrush current are achieved in the scenario of multiple battery packs in parallel. In the discharge mode, the charging MOSFET is turned on first and the body diode of the charging MOSFET is used to block the reverse circulating current. In the charging mode, the charging MOSFET is turned on first and the body diode of the discharging MOSFET is used to block the forward circulating current. After the current is stabilized, the other MOSFET is turned on to complete the efficient output.

[0037] Each battery pack executes the above logic independently. Without increasing hardware costs such as cement resistors, relying on multi-pack communication synchronization, or occupying additional PCB space, it completes the entire process control from working mode recognition to loop circuit disconnection and stable system output. This significantly improves the safety and reliability of the parallel system while effectively avoiding the inherent defects of traditional P- disconnection schemes, such as bulky size, high heat generation, and high cost, as well as P+ disconnection schemes, such as high communication synchronization requirements, brief impact of body diodes, and logic disorder and loss of control. It successfully solves the common industry problem of lithium battery modules being unable to balance low cost, small size, and high safety in multi-pack parallel operation. Attached Figure Description

[0038] Figure 1 A schematic diagram of an existing charge and discharge control circuit;

[0039] Figure 2 This is a schematic diagram of an existing pre-discharge control circuit;

[0040] Figure 3 This is a schematic diagram of the method steps of the present invention;

[0041] Figure 4 This is a flowchart of the software control process of the present invention. Detailed Implementation

[0042] The technical solutions in 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.

[0043] In the field of lithium battery modules and battery pack management, multi-pack parallel capacity expansion technology serves as a core hub for improving system power density and energy capacity, undertaking the key tasks of meeting the endurance requirements of high-load equipment and enhancing system redundancy and reliability. Among these, achieving autonomous current sharing among parallel battery packs and suppressing inter-pack circulating currents are fundamental prerequisites for ensuring long cycle life and high safety of lithium battery modules.

[0044] However, in actual operating conditions, especially when multiple battery packs are directly connected to the bus due to differences in initial state (such as open-circuit voltage, internal resistance, and SOC), the stability of the BMS system faces severe challenges. The sudden parallel connection of battery packs usually means an instantaneous voltage mismatch. Given the limited speed of conventional voltage detection and communication handshakes, battery packs with large voltage differences will form a low-impedance loop through their body diodes. To compensate for the bus voltage difference, the higher-voltage battery pack will continuously charge the lower-voltage pack due to the potential difference. Once grid connection is complete, this instantaneous impact will force a sharp jump in the mutual charging current, forming a very large current spike. This may not only trigger hardware overcurrent protection, but in severe cases, it can even directly damage the battery cells due to thermal runaway and internal short circuits caused by the large current mutual charging.

[0045] To address the above issues, the industry currently employs two main approaches:

[0046] Please see Figure 1 , Figure 2As shown, one approach employs a pre-charge current-limiting technology using a P-type topology combined with a cement resistor. This scheme connects a power-type cement resistor in series at the negative terminal of the battery pack, limiting the inrush current during grid connection through physical impedance. Although this method can suppress instantaneous overcurrent through the energy dissipation characteristics of passive components, it is essentially a passive "energy-dissipating" protection method and does not cut off the mutual charging path from the circuit topology. Therefore, the system often suffers from problems such as bulky size, high heat generation, and high energy loss. Furthermore, the fixed resistance value cannot be flexibly adapted to different differential pressure conditions, and it still cannot effectively prevent circulating current collapse caused by excessive internal resistance differences.

[0047] Secondly, a pre-charge enable control strategy using a P+ disconnect topology is employed. This scheme attempts to optimize the MOSFET drive logic so that only the charging MOSFET is turned on during grid connection (utilizing the unidirectional conductivity of its body diode), and the discharging MOSFET is turned on only after the current stabilizes. However, this scheme introduces new inherent limitations in engineering applications: if the matching relationship between the current threshold and the delay time is not properly set, especially in scenarios with large voltage differentials in parallel, the brief conduction of the body diode can still introduce instantaneous shocks; at the same time, the synchronization requirements for multi-packet communication are extremely high. Once the master-slave control deviates, logic disorder can easily lead to shoot-through of the upper and lower MOSFETs, greatly threatening the safe operation of the system.

[0048] In summary, existing parallel protection technologies for lithium battery modules generally face a dilemma when dealing with multiple battery packs operating in parallel: delayed protection action and high hardware costs. They cannot achieve precise suppression and smooth recovery of inrush current while maintaining low cost and small size. These inherent defects not only restrict the safe application of lithium battery packs in cost-sensitive scenarios such as lawnmowers, but also increase the design redundancy and safety risks of battery management systems.

[0049] Therefore, please refer to Figure 3 , Figure 4 The present invention aims to provide a method for controlling reverse charging in parallel with a battery pack, comprising the following steps:

[0050] Step S1: Construct a multi-battery pack working mode discrimination platform based on key wake-up and communication recognition.

[0051] This platform forms the basis for implementing the method of this invention. Its core lies in utilizing the key signal Car_Key and communication commands TX0 / RX0 to collaboratively determine the current system's operating mode, providing accurate logical basis for the subsequent differentiated control of the charging and discharging MOSFETs. Specifically:

[0052] Operating mode determination: After the system is powered on or woken up, the microcontroller monitors the key signal and communication commands in real time. If a valid key signal is detected, the system is determined to enter the discharge mode and prepares to supply power to the load; if no key signal is detected but a charging command is received from the control board, the system is determined to enter the charging mode and prepares to connect to the charger for charging.

[0053] Step S2: Execute progressive turn-on control of MOSFETs in discharge mode.

[0054] Once the system is determined to have entered discharge mode, the microcontroller executes a progressive turn-on control process for the MOSFET based on current detection, as follows:

[0055] Discharge MOSFET priority turn-on: The microcontroller first turns on the discharge MOSFET MQ3, while the charging MOSFET MQ2 remains off. The battery pack forms a discharge circuit through the channel of the discharge MOSFET and the body diode of the charging MOSFET, realizing power supply to the main control board and load for startup.

[0056] Current detection and threshold judgment: The system samples the discharge circuit current value in real time. Let the current sampled current be I, and compare it with the preset current threshold Ith (e.g., 2A). If I < Ith, the current state is maintained and the charging MOSFET remains off; if I ≥ Ith, the delayed confirmation process is initiated.

[0057] Delay confirmation and charging MOSFET turn-on: When the discharge current is detected to reach or exceed the threshold Ith, a timer is started for delay judgment. If the current remains above the threshold within the set delay time Td (e.g., 2 seconds), it is confirmed that the load has been stably connected and is in normal working condition. At this time, the microcontroller turns on the charging MOSFET MQ2, making all charging and discharging MOSFETs conduct, short-circuiting the battery pack body diode, eliminating the loss caused by the forward voltage drop of the body diode, and achieving efficient and stable discharge output.

[0058] Step S3: Perform differential turn-on control of MOSFETs in charging mode.

[0059] Once the system determines that it has entered charging mode, the microcontroller executes a differentiated MOSFET turn-on control process based on charger access detection, as follows:

[0060] Charging MOSFETs are turned on first: The microcontroller first turns on the charging MOSFET MQ2, while the discharging MOSFET MQ3 remains off. The charger charges the battery pack through the channel of the charging MOSFET and the body diode of the discharging MOSFET, thus establishing the charging circuit.

[0061] Current detection and threshold judgment: The system samples the charging circuit current value in real time. Let the current sampled current be I, and compare it with the preset current threshold Ith (e.g., 2A). If I < Ith, the current state is maintained and the discharge MOSFET remains off; if I ≥ Ith, the system enters the delayed confirmation process.

[0062] Delay confirmation and discharge MOSFET turn-on: When the charging current is detected to reach or exceed the threshold Ith, a timer is started for delay judgment. If the current remains above the threshold within the set delay time Td (e.g., 2 seconds), it is confirmed that the charger is stably connected and in a high-current charging state. At this time, the microcontroller turns on the discharge MOSFET MQ3, making all charging and discharging MOSFETs conduct, short-circuiting the battery pack diodes, and reducing charging circuit losses.

[0063] Step S4: Perform synchronous control and mutual charging suppression in the scenario of multiple battery packs in parallel.

[0064] In scenarios where multiple battery packs are connected in parallel to the control board, each battery pack independently executes the control logic of step S2 or S3 above, maintaining command synchronization with the main control board via the communication bus. The specific effects are as follows:

[0065] Parallel Discharge Scenario: Multiple battery packs simultaneously receive discharge commands from the main control board. Each battery pack independently executes step S2, first turning on the power MOSFET while keeping the charging MOSFET off. Since the charging MOSFET is not turned on, the P- terminals of each battery pack are isolated from each other by body diodes, preventing the formation of a low-impedance loop even with voltage differences. Only when the discharge current of a battery pack reaches a threshold and remains stable is its charging MOSFET turned on. At this point, due to voltage balance, there is no impactive mutual charging current between this battery pack and other battery packs with their charging MOSFETs turned on.

[0066] Parallel charging scenario: Multiple battery packs simultaneously receive charging commands from the main control board. Each battery pack independently executes step S3, first turning on the charging MOSFET while keeping the discharging MOSFET off. Because the discharging MOSFET is not turned on, the battery packs cannot form a mutual charging path through the discharge circuit. Only when the charging current of a battery pack reaches a threshold and remains stable is its discharging MOSFET turned on, at which point that battery pack is in a stable charging state along with the other battery packs.

[0067] Step S5: Perform full shutdown control of MOSFETs in power-off and standby states.

[0068] When the key signal is detected to be off or a shutdown command is received from the main control board, the microcontroller immediately executes the full shutdown control of the MOSFETs, and simultaneously shuts down the charging MOSFET MQ2 and the discharging MOSFET MQ3, so that the battery pack is completely disconnected from the external circuit and enters standby or hibernation mode to ensure system safety.

[0069] In summary, this invention achieves safe access and mutual charging suppression in multi-battery pack parallel scenarios by combining operating mode discrimination with progressive conduction control of the charging and discharging MOSFETs. In discharge mode, the charging MOSFET is turned on first, utilizing the body diode of the charging MOSFET for isolation and loop flow; in charging mode, the charging MOSFET is turned on first, utilizing the body diode of the discharging MOSFET for isolation and loop flow; after the current stabilizes, the other MOSFET is turned on, completely eliminating body diode losses. This method avoids the problems of bulky size, high heat generation, and high energy consumption caused by the cement resistor in the traditional P-disconnect scheme, and also avoids the logic disorder and instantaneous impact risks caused by communication synchronization deviations in the P+ disconnect scheme, significantly improving the safety and reliability of multi-battery pack parallel systems.

[0070] The key innovations of this invention are as follows:

[0071] Firstly, a current-bootstrapping-based bidirectional MOSFET progressive turn-on control logic is proposed. In discharge mode, the charging MOSFET is turned on first, using the body diode of the charging MOSFET to prevent reverse charging; in charging mode, the charging MOSFET is turned on first, using the body diode of the discharging MOSFET to prevent forward charging. Through a current threshold and delay confirmation mechanism, the other MOSFET is only turned on after the load or charger is stably connected, thus achieving complete disconnection of the circulating current path and effective suppression of inrush current.

[0072] Secondly, an adaptive conduction determination method based on real-time current detection was constructed. By preset a current threshold and delay time, the timing of the MOSFET's full conduction is matched with the actual operating conditions. Under low current conditions, a single MOSFET remains on, utilizing the body diode for natural isolation; after the high current stabilizes, the other MOSFET is turned on, reducing conduction losses. This method eliminates the need for complex communication synchronization, allowing each battery pack to make independent decisions, fundamentally solving the control disorder problem caused by communication deviations when multiple packs are connected in parallel.

[0073] Third, it achieves a pure software solution with zero hardware increments. This invention does not require additional cement resistors, pre-charge relays, or complex external detection circuits. Relying solely on the microcontroller's built-in current sampling and timer resources, it can achieve multi-packet parallel protection through optimized control logic, significantly reducing system BOM costs and PCB area occupancy while ensuring safety.

[0074] The advantages of this invention are:

[0075] First, it significantly improves the safety and reliability of multi-pack parallel systems. In both discharging and charging modes, it effectively cuts off the circulating current path, completely eliminating inter-pack mutual charging current caused by voltage differences, avoiding cell damage and thermal runaway risks, and greatly enhancing the system's operational stability under multi-pack parallel operation conditions.

[0076] Secondly, it saves on hardware costs and space. Because this invention solves the mutual charging suppression problem at the control algorithm level, it does not rely on passive energy-consuming devices such as cement resistors, thus eliminating the need for corresponding power resistors and heat dissipation structures, reducing system BOM costs and overall machine size. It is especially suitable for garden tools such as lawnmowers that are sensitive to cost and space.

[0077] Third, the software algorithm is simple, efficient, and resource-efficient. The current threshold comparison and delay confirmation logic is clear, with minimal computation, requiring only a few timers and comparison operations. It does not consume excessive MCU computing resources and storage space, ensuring the normal operation of the battery pack's routine management functions.

[0078] Fourth, it has strong compatibility and is easy to promote. This invention does not change the existing battery pack hardware topology; it can be implemented simply by optimizing the microcontroller control program. It can be directly applied to various BMS products with P+ or P- disconnection architectures, and has good engineering compatibility and promotional value.

[0079] In summary, the parallel reverse charging control method for battery packs provided by this invention can achieve safe access and mutual charging suppression in scenarios with multiple battery packs connected in parallel using a simple software algorithm. It effectively avoids the problems of control lag, circulating current impact, high hardware cost, bulky size and communication disorder faced by traditional solutions when dealing with multiple packs. It significantly improves the safety and reliability of lithium battery modules in parallel applications, while also having the advantages of low hardware cost, low resource consumption and easy implementation. It has extremely high practical value and promotion prospects.

[0080] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended technical solutions and their equivalents.

Claims

1. A method for controlling reverse charging in parallel with a battery pack, characterized in that, Includes the following steps: Step S1: Construct a multi-battery pack working mode discrimination platform based on key wake-up and communication recognition, and use key signals and communication commands to jointly determine whether the current system is in discharge mode or charging mode; Step S2: When the system is determined to enter the discharge mode, the progressive conduction control of the MOSFET in the discharge mode is executed. The discharge MOSFET is turned on first, and the body diode of the charging MOSFET is used to isolate the loop current path. After the discharge current is detected to reach the preset threshold and remain stable, the charging MOSFET is turned on. Step S3: When the system is determined to enter the charging mode, the differential conduction control of the MOSFET in the charging mode is executed. The charging MOSFET is turned on first, the body diode of the discharging MOSFET is used to isolate the loop current path, and the discharging MOSFET is turned on after the charging current reaches the preset threshold and remains stable. Step S4: In the scenario of multiple battery packs in parallel, each battery pack independently executes the control logic of step S2 or step S3 above, and the physical isolation of the circulating current path is achieved through the body diode of the charging MOSFET or discharging MOSFET of each battery pack, thereby suppressing the mutual charging current between the packs. Step S5: When the key signal is detected to be off or a shutdown command is received, execute the full shutdown control of the MOSFET, and simultaneously shut down the charging MOSFET and the discharging MOSFET, so that the battery pack is completely disconnected from the external circuit.

2. The parallel anti-reverse charging control method for battery packs according to claim 1, characterized in that: In step S1, the microcontroller monitors the key signal Car_Key and the communication commands TX0 / RX0 in real time. If a valid key signal is detected, the system is determined to enter the discharge mode; If no key signal is detected but a charging command is received from the control board, the system is determined to enter charging mode.

3. The parallel anti-reverse charging control method for battery packs according to claim 1, characterized in that: The progressive turn-on control of the MOSFET in the discharge mode in step S2 specifically includes: The microcontroller first turns on the discharge MOSFET, while the charging MOSFET remains off. The battery pack forms a discharge circuit through the channel of the discharge MOSFET and the body diode of the charging MOSFET. The discharge circuit current value I is sampled in real time and compared with the preset current threshold Ith; If I < Ith, then maintain the current state and keep the charging MOSFET off; If I≥Ith, then the timer is started to perform a delay judgment. If the current remains above the threshold within the set delay time Td, then the charging MOSFET is turned on, so that all charging and discharging MOSFETs are turned on.

4. The parallel anti-reverse charging control method for battery packs according to claim 1, characterized in that: The differential turn-on control of the MOSFET in the charging mode in step S3 specifically includes: The microcontroller first turns on the charging MOSFET, while the discharging MOSFET remains off. The charger charges the battery pack through the channel of the charging MOSFET and the body diode of the discharging MOSFET. The charging circuit current value I is sampled in real time and compared with the preset current threshold Ith; If I < Ith, then maintain the current state and keep the discharge MOSFET off; If I≥Ith, then the timer is started to perform a delay judgment. If the current remains above the threshold within the set delay time Td, then the discharge MOSFET is turned on, so that all the charging and discharging MOSFETs are turned on.

5. The parallel anti-reverse charging control method for battery packs according to claim 1, characterized in that: In step S4, in the parallel discharge scenario, multiple battery packs simultaneously receive discharge commands from the main control board. Each battery pack independently executes the control logic of step S2, first turning on the power MOS and keeping the charging MOS off. The P- terminals of each battery pack are isolated from each other by the body diode of the charging MOS. Only when the discharge current of a certain battery pack reaches the threshold and remains stable is its charging MOS turned on.

6. The parallel anti-reverse charging control method for battery packs according to claim 1, characterized in that: In step S4, in the parallel charging scenario, multiple battery packs simultaneously receive charging commands from the main control board. Each battery pack independently executes the control logic of step S3, first turning on the charging MOS and keeping the discharging MOS off. The battery packs are isolated from each other by the body diode of the discharging MOS. Only when the charging current of a certain battery pack reaches the threshold and remains stable is its discharging MOS turned on.

7. The parallel anti-reverse charging control method for battery packs according to claim 1, characterized in that: In step S5, when the key signal is detected to be off or a shutdown command is received from the main control board, the microcontroller immediately shuts down the charging MOSFET and the discharging MOSFET simultaneously, so that the battery pack enters standby or hibernation state.

8. The parallel anti-reverse charging control method for battery packs according to any one of claims 1-7, characterized in that: The preset current threshold Ith is 2A, and the preset delay time Td is 2 seconds; the current threshold and delay time are preset fixed values ​​or adjustable parameters based on the battery pack characteristics and system requirements.

9. The parallel anti-reverse charging control method for battery packs according to claim 1, characterized in that: The method is implemented using the current sampling module and timer resources built into the microcontroller.

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