A+B dual lithium battery pack non-inductive switching control system and method

Abstract

The application discloses an A+B dual-lithium battery pack non-inductive switching control system and method, belongs to the new energy automobile power battery management technology field, and comprises a main battery A pack, an auxiliary battery B pack, a 200A fast-fuse fuse, a vehicle controller VCU, a motor controller MCU and a DC-DC conversion module. Four technical problems of reverse charging risk, power output interruption, 12V power supply interruption and communication conflict in the dual-pack switching process are solved fundamentally, safe, smooth and user non-inductive switching of the main battery A and the auxiliary battery B in the vehicle driving state is realized, and the system reliability and the driving safety are improved.

Description

Technical Field

[0001] This invention relates to the field of power battery management technology for new energy vehicles, specifically to a seamless switching control system and method for A+B dual lithium battery packs. Background Technology

[0002] Currently, mainstream pure electric vehicles use a single battery pack as the sole high-voltage power source. To extend the vehicle's range, the industry commonly employs external auxiliary battery packs as a range extender. Existing dual-battery switching control schemes suffer from multiple safety flaws and performance shortcomings. Existing patent CN110783642A discloses a dual-battery contactor switching architecture, which relies solely on mechanical contactors for hard switching and lacks voltage difference prediction and power transistor timing hierarchical control mechanisms. Common defects of similar technologies in the industry are as follows:

[0003] 1. Reverse charging poses an extremely high safety risk. Battery switching is achieved solely by switching on and off using a contactor without pre-blocking the charging circuit. When there is a voltage difference between the main and auxiliary battery pack terminals, a massive instantaneous reverse current of several thousand amps is generated during the switching process. This can easily damage the MOSFETs on the battery protection board, burn out the high-voltage wiring harness, and, under extreme conditions, cause thermal runaway of the battery cells and even a fire in the entire vehicle.

[0004] 2. Power output interruption poses significant safety hazards. Most dual-pack switching logics require the entire vehicle to cut off high-voltage output and the motor to stop working before the switching is completed. During the switching process, the entire vehicle loses high-voltage power, the 12V low-voltage DC-DC stops working, and power steering and brake assist are lost. There are significant safety risks when switching at high speeds. Some parallel switching schemes lack transition timing, and sudden changes in load current cause severe power shocks, resulting in a poor driving experience.

[0005] 3. The switching logic is simplistic and has poor adaptability to different operating conditions. The existing solution relies solely on a single SOC threshold to trigger battery switching, without considering multi-dimensional vehicle operating condition constraints such as vehicle speed, gear position, brake feedback, and real-time discharge current. Forcibly switching during high-current discharge and energy feedback phases can trigger battery overcurrent protection, cause drastic fluctuations in motor torque, and frequently result in erroneous shutdowns of the protection board.

[0006] 4. The communication network architecture is unstable and the system has a low fault tolerance rate. Traditional dual battery packs share the same CAN bus ID range. The status messages and control command messages of battery packs A and B conflict with each other. The vehicle controller (VCU) and motor controller (MCU) cannot accurately identify the real-time status of the two packs. Message loss and signal disorder occur frequently, and the control logic of the vehicle power system is disordered.

[0007] In summary, existing dual-battery switching technology cannot simultaneously guarantee switching safety, power continuity, and communication stability, making it difficult to meet the usage requirements of smooth and seamless switching between main and auxiliary battery packs during dynamic driving of passenger vehicles. Summary of the Invention

[0008] The present invention aims to solve the above-mentioned technical problems by providing a seamless switching control system and method for A+B dual lithium battery packs.

[0009] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0010] A seamless switching control system for A+B dual lithium battery packs includes a main battery pack A, an auxiliary battery pack B, a 200A fast-blow fuse, a vehicle control unit (VCU), a motor control unit (MCU), a DC-DC converter module, and a drive motor.

[0011] The main battery pack A includes a pack of cells and a pack BMS management unit. The pack BMS management unit has a built-in pack B MOS transistor control instruction set, which can scan and identify the CAN identifier of the auxiliary battery pack B and enter the A+B collaborative working mode.

[0012] The auxiliary battery pack B includes a B pack of battery cells, a B pack BMS management unit, and an independent CAN communication module. The independent CAN communication module is physically isolated from the communication bus of pack A and is assigned a dedicated CANID segment. The B pack BMS management unit reports the battery status in real time and receives MOS transistor on / off control commands issued by the B pack A BMS management unit.

[0013] The 200A fast-blow fuse is connected in series between the high-voltage positive terminal of the main battery pack A and the high-voltage positive terminal of the auxiliary battery pack B.

[0014] The vehicle controller (VCU) and motor controller (MCU) are connected to the main CAN bus of the main battery pack A. Before switching to start, the vehicle controller (VCU) synchronously sends a command to the motor controller (MCU) to disable motor feedback and discharge current limiting.

[0015] The high voltage output of the main battery pack A is supplied to the drive motor, and the drive motor supplies power to the 12V low voltage load through the DC-DC conversion module.

[0016] According to claim 1, the seamless switching control system for A+B dual lithium battery packs is characterized in that: battery switching initiation requires simultaneous fulfillment of three constraint conditions, the three constraint conditions including:

[0017] Power constraint: Auxiliary battery pack B has a remaining capacity of ≥15Ah;

[0018] Battery state constraint: The SOC of main battery pack A drops to the preset power reduction capacity threshold;

[0019] Vehicle operating condition constraints: real-time vehicle speed ≤ 15km / h, vehicle gear is N (neutral) or R (reverse), no motor braking feedback request, and discharge current < 30A;

[0020] The triple constraint parameters support vehicle calibration adjustments, and the switching process is locked if any condition is not met.

[0021] Preferably, the switching from main power supply from main battery pack A to main power supply from auxiliary battery pack B adopts a four-step MOSFET hierarchical timing control, with the steps as follows:

[0022] Step 1: The main battery A pack sends a command to turn off the charging MOSFET of the main battery A pack, cutting off the reverse charging path between the two packs;

[0023] Step 2: Turn on the discharge MOSFET of auxiliary battery pack B to achieve short-term parallel transition power supply of battery packs A and B;

[0024] Step 3: Turn off the discharge MOSFET of main battery A, disconnecting main battery A from the high-voltage power supply circuit;

[0025] Step 4: During charging, turn on the charging MOSFET of auxiliary battery B to complete the power supply of auxiliary battery B.

[0026] When switching from auxiliary battery B to main battery A, the switching logic is completely symmetrical, the steps are executed in reverse order, and the interval between all steps is ≤100ms.

[0027] Preferably, the independent CAN communication module uses a TJA1051 transceiver. The CAN bus ID segment of the main battery A pack is 0x100~0x1FF, and the dedicated isolated CAN ID segment of the auxiliary battery B pack is 0x300~0x3FF. The dual CAN bus isolation architecture ensures that the peak bus network load is ≤22% and the message loss rate is <0.01%.

[0028] Preferably, the A-pack BMS has built-in dual-pack collaborative charging control logic; after the charger is woken up, the A-pack BMS management unit detects the current main battery.

[0029] If the current main battery is auxiliary battery pack B, then charge auxiliary battery pack B directly.

[0030] If the current main battery is the main battery pack A and the SOC of the auxiliary battery pack B is greater than 80%, the main battery pack A will be automatically switched to the auxiliary battery pack B and then the auxiliary battery pack B will be charged.

[0031] Under low-temperature charging conditions, the BMS management unit of package A sends a preheating command to the BMS management unit of package B to heat the generator cells.

[0032] Preferably, the CAN communication ID segment of the auxiliary battery pack B is physically isolated from the main battery pack A, and the peak load of the dual-pack CAN bus is ≤25%.

[0033] This invention also provides a method for seamless switching control of A+B dual lithium battery packs, comprising the following steps:

[0034] S1, the vehicle controller VCU and the A-package BMS management unit collect the dual-package power, SOC, vehicle speed, gear position, motor feedback status, and high-voltage discharge current in real time, and continuously verify the triple switching constraints.

[0035] S2. After all three constraints are met, the vehicle controller (VCU) sends a coordinated control command to the motor controller (MCU) to turn off the motor energy feedback and limit the maximum discharge current of the motor.

[0036] S3 and A package BMS management units issue charging and discharging MOSFET on / off commands in sequence according to the four-step hierarchical MOSFET timing sequence to complete the dual-package parallel transition and main power supply switching.

[0037] S4. After all the switching processes are completed, the vehicle controller (VCU) removes the current limiting and feedback disabling restrictions of the motor controller (MCU) and restores the complete power output control of the motor.

[0038] S5: Under charging conditions, it automatically selects the charging battery based on the dual-pack SOC and issues a preheating command for the auxiliary battery B pack cells in low-temperature environments.

[0039] This invention, through isolated dual CAN communication, physical safety protection, triple operating condition constraint judgment, and parallel transition four-step timing control, has achieved the following quantifiable technical advantages through bench simulation and real vehicle installation verification:

[0040] 1. The invention significantly improves safety performance with dual protection of pre-cut-off charging MOS and 200A fast fuse in the double enclosure, reducing the reverse charging failure rate to 0, and reducing the failure of MOS breakdown and wire harness burnout on the battery protection board by 100%, thus completely eliminating the risk of cell thermal runaway caused by differential pressure backflow.

[0041] 2. The power supply of this invention is completely continuous, with no driving safety hazards. The switching process adopts a short-time parallel transition architecture, with continuous high-voltage power supply to the whole vehicle, uninterrupted operation of the DC-DC module, and no power outage of the 12V low-voltage load; the high-voltage power output fluctuation range is <3%, and the steering and braking assistance are effective throughout the entire process, eliminating the safety accident of power failure during switching.

[0042] 3. This invention provides a seamless driving experience with excellent smoothness. The total switching time is less than 100ms, and drivers and passengers do not experience any power jerking under low-speed urban conditions. In real vehicle testing, the torque fluctuation is only 7.2% of the motor's rated torque, and the instrument panel's SOC value is seamlessly connected without any jumps or black screen issues.

[0043] 4. Significantly optimized CAN communication stability: Physical isolation of A and B packets on the CAN bus and independent allocation of ID intervals reduce the peak bus network load from 35% in the existing scheme to 22%, with a message loss rate of <0.01%, completely solving the problems of message conflict and incorrect battery status identification.

[0044] 5. Platform compatibility and strong adaptability: Both Pack A and Pack B can be used independently as power batteries for single vehicles without large-scale hardware modifications. Upgrading the Pack A BMS firmware is sufficient to achieve dual-pack collaboration, resulting in low vehicle development and modification costs. Switching constraint thresholds and timing delay parameters support vehicle calibration and are compatible with lithium iron phosphate / ternary lithium battery packs of different capacities and voltage systems.

[0045] 6. Improved Low-Temperature Charging Efficiency: The addition of remote preheating and collaborative control for the B-pack improves the acceptance of cell charging in low-temperature environments, reduces charging heat loss, and extends battery cycle life. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0047] The present invention will now be described in further detail with reference to the full text.

[0048] Combined with appendix Figure 1 A seamless switching control system for A+B dual lithium battery packs based on power coordination and state constraints is proposed. The system includes a main battery pack A, an auxiliary battery pack B, a 200A fast-blow fuse, a vehicle controller (VCU), a motor controller (MCU), and a DC-DC converter module. It fundamentally solves four major technical challenges in the switching process between the two packs: reverse charging risk, power output interruption, 12V power supply interruption, and communication conflict. This enables safe, smooth, and seamless switching between the main battery A and the auxiliary battery B while the vehicle is in motion, improving system reliability and driving safety.

[0049] Main Battery Pack A: Includes Pack A cell assembly and Pack A BMS management unit; Pack A BMS has built-in upgraded firmware, adding a complete set of Pack B MOS transistor control instructions (including Pack B discharge MOS on / off and charge MOS on / off instructions), which can scan the Pack B exclusive CAN identifier on the bus in real time, and automatically enter the A+B collaborative working mode after identifying Pack B online; Pack A BMS interacts with VCU and MCU through the original CAN bus (ID segment 0x100~0x1FF).

[0050] Auxiliary Battery Pack B: Includes Pack B cell assembly, Pack B Management System (BMS) unit, and independent CAN communication module; The independent CAN communication module uses a TJA1051 transceiver, is physically isolated from Pack A's CAN bus, and is assigned a dedicated ID segment 0x300~0x3FF; Pack B's BMS reports its own voltage, current, SOC, cell temperature, and fault codes in real time, and synchronously receives charging MOS and discharging MOS on / off control commands from Pack A's BMS.

[0051] Specifically, the auxiliary battery pack B is equipped with an independent CAN communication module (physical layer isolation, dedicated ID segment allocation) to report real-time voltage, current, SOC, temperature, and fault codes, and to receive MOS control commands from pack A; • A 200A fast-blow fuse (safety fuse) is connected in series between the two packs as the last line of defense for physical blocking of reverse current; • The vehicle controller (VCU) and motor controller (MCU) receive the status of pack A through the CAN bus, and after the switching command is issued, they synchronously perform coordinated actions such as disabling feedback, limiting discharge current to 30A, and maintaining continuous 12VDC-DC power supply.

[0052] Safety protection components: A 200A fast-blow fuse is connected in series between the high voltage positive terminal of package A and the high voltage positive terminal of package B, serving as the last physical protection barrier to block reverse current.

[0053] Vehicle control components: VCU and MCU are connected to the main CAN bus of package A; before executing the switching command, VCU sends a coordinated control command to MCU to simultaneously disable motor brake feedback and limit the motor discharge current to within 30A; DC-DC conversion module continuously supplies power to 12V low-voltage load, and keeps working without restarting throughout the switching process.

[0054] Power actuator: The main positive contactor is connected in series between the output terminal of package A BMS and the drive motor, and its on / off state is controlled by package A BMS.

[0055] Intelligent switching control logic (triple constraints + four-step MOSFET timing):

[0056] Triple operating condition constraint triggering conditions (all conditions must be met for the switching process to start; parameters support vehicle calibration):

[0057] (1) Power constraint: The remaining capacity of auxiliary battery pack B is ≥15Ah;

[0058] (2) Battery state constraint: The SOC of the main battery A pack drops to the preset capacity threshold corresponding to the power reduction (the SOC corresponding to 15Ah).

[0059] (3) Vehicle operating conditions constraints: real-time vehicle speed ≤ 15km / h, vehicle gear is N neutral / R reverse, no motor braking feedback request, high voltage discharge current < 30A.

[0060] When all three constraints are met, the BMS of package A sends a switching ready signal to the VCU, and the VCU synchronously controls the MCU to perform feedback shutdown and discharge current limiting preprocessing; if any one constraint is not met, the switching function is locked until the operating conditions meet the requirements.

[0061] Four-step hierarchical MOSFET timing switching (taking the switch from main supply of package A to main supply of package B as an example):

[0062] Step 1: The BMS of Packet A issues a command to turn off the charging MOSFET of Packet A, completely cutting off the external charging path of Packet A and eliminating the physical path of reverse charging between the two packs;

[0063] Step 2: After a delay of ≤100ms, a command is issued to turn on the discharge MOSFET of pack B, and packs A and B form a short-term parallel transition circuit; because the preset resting voltage of pack B is higher than that of pack A, the load current naturally flows to pack B, and there is no instantaneous inrush current.

[0064] Step 3: After a delay of ≤100ms, issue a command to turn off the discharge MOSFET of Packet A, completely disconnecting Packet A from the high-voltage power supply circuit, and Packet B independently bears the load of the entire vehicle;

[0065] Step 4: In the charging scenario, a command is issued to activate the charging MOSFET of Pack B, completing the takeover of all power supply and charging functions of Pack B.

[0066] When switching from main supply of package B back to main supply of package A, a fully symmetrical reverse four-step timing sequence is executed, with the interval between each step uniformly controlled within 100ms, and the total switching time is lower than the human body's dynamic perception threshold.

[0067] Specifically, as shown below:

[0068]

[0069] Dual-pack collaborative charging and low-temperature preheating strategy:

[0070] After the charger is powered on and woken up, the BMS of Pack A identifies the current main power supply battery; if the current power supply is from Pack B, the charging process of Pack B is started directly; if Pack A is the main power supply and Pack B's SOC is greater than 80%, the A→B switch is automatically triggered and Pack B is charged.

[0071] Under low-temperature charging conditions, the BMS of Pack A sends a cell heating start command to the BMS of Pack B. Pack B then activates its built-in heating film to preheat the cells, thereby improving the charging acceptance capability in low-temperature environments and reducing low-temperature charging losses.

[0072] This invention includes a seamless switching control method.

[0073] The seamless switching control method for A+B dual lithium battery packs based on the above control system includes the following steps:

[0074] S1. The vehicle VCU and A-pack BMS collect dual-pack power parameters, battery SOC, vehicle speed, gear position, motor feedback status, and high-voltage discharge current in real time and continuously judge the triple switching constraints.

[0075] S2. After all three constraints are met, the VCU sends a collaborative control command to the MCU to turn off the motor energy feedback function and limit the maximum discharge current of the motor.

[0076] S3 and A pack BMS, according to the four-step hierarchical MOSFET timing sequence, sequentially issue charging and discharging MOSFET on / off control commands to each battery pack to complete the parallel transition of the two packs and the switching of the main power supply.

[0077] S4. After the entire switching process is completed, the VCU removes the MCU current limiting and feedback disabling restrictions and restores the normal power output control logic of the motor.

[0078] S5. Under charging conditions, automatically select the charging battery based on the SOC status of both packs, and issue a preheating command for pack B when the temperature is low.

[0079] Example 1: 11.52kWh main A pack + 6kWh range extender B pack lithium iron phosphate pure electric car.

[0080] Hardware setup: Main battery pack A: 11.52kWh lithium iron phosphate PACK, original A pack BMS upgraded firmware, written with B pack MOS control instruction set, main CAN bus assigned ID range 0x100~0x1FF; Auxiliary battery pack B: 6kWh external lithium iron phosphate range extender PACK, equipped with B pack dedicated BMS, matched with TJA1051 isolated CAN transceiver, independent CANID range 0x300~0x3FF; 200A fast fuse connected in series between the high voltage positive terminals of A and B packs; A pack BMS high voltage output connected to drive motor and DC-DC module via main positive contactor; VCU and MCU connected to A pack main CAN bus.

[0081] The calibration parameters are set with triple switching constraints: B package remaining capacity ≥ 15Ah; A package SOC drops to the corresponding 15Ah capacity threshold; vehicle speed ≤ 12km / h, N / R gear, no feedback request, discharge current ≤ 25A; MOS timing interval: 8ms delay per step, total switching time 30ms.

[0082] Switching process (A→B switching): At time t0: The BMS of package A detects that all triple constraints are met, and the VCU instructs the MCU to turn off feedback and limit the discharge current to 25A; it also issues a command to turn off the charging MOS of package A, blocking the reverse charging circuit; at t0+8ms: a command is issued to turn on the discharging MOS of package B, and packages A and B output in parallel. The open circuit voltage of package B is 86.1V and that of package A is 76.4V, and the load current naturally flows to package B; at t0+16ms: a command is issued to turn off the discharging MOS of package A, and package A exits the power supply circuit; at t0+24ms: when the vehicle is connected to the charging gun, a command is issued to turn on the charging MOS of package B, completing the switching.

[0083] In real-vehicle testing, the entire switching process was continuously operated by DC-DC converter. The 12V low-voltage voltage only dropped slightly from 13.8V to 13.75V, with no low-voltage restart. The motor torque fluctuation was only -7.2% of the rated value, resulting in a smooth driving experience. No reverse current was generated, the bus load was 21%, and no messages were lost. In low-temperature charging mode, the heating film of the B pack was remotely activated by the A pack, and the temperature rise of the battery cells during charging was uniform.

[0084] The present invention and its embodiments have been described above. This description is not restrictive, and the embodiments shown throughout are only one of the embodiments of the present invention. The actual structure is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A seamless switching control system for A+B dual lithium battery packs, characterized in that, This includes the main battery pack A, auxiliary battery pack B, 200A fast-blow fuse, vehicle control unit (VCU), motor control unit (MCU), DC-DC converter module, and drive motor. The main battery pack A includes a pack of cells and a pack BMS management unit. The pack BMS management unit has a built-in pack B MOS transistor control instruction set, which can scan and identify the CAN identifier of the auxiliary battery pack B and enter the A+B collaborative working mode. The auxiliary battery pack B includes a pack of cells, a pack of management system (BMS) management unit, and an independent CAN communication module. The independent CAN communication module is physically isolated from the communication bus of pack A and is assigned a dedicated CANID segment. The pack of management system (BMS) management unit reports the battery status in real time and receives MOSFET on / off control commands issued by the pack of management system (BMS) management unit. The 200A fast-blow fuse is connected in series between the high-voltage positive terminal of the main battery pack A and the high-voltage positive terminal of the auxiliary battery pack B. The vehicle controller (VCU) and motor controller (MCU) are connected to the main CAN bus of the main battery pack A. Before switching to start, the vehicle controller (VCU) synchronously sends a command to the motor controller (MCU) to disable motor feedback and discharge current limiting. The high voltage output of the main battery pack A is supplied to the drive motor, and the drive motor supplies power to the 12V low voltage load through the DC-DC conversion module.

2. The seamless switching control system for A+B dual lithium battery packs according to claim 1, characterized in that: Battery switching startup requires the simultaneous fulfillment of three constraints, which include: Power constraint: Auxiliary battery pack B has a remaining capacity of ≥15Ah; Battery state constraint: The SOC of main battery pack A drops to the preset power reduction capacity threshold; Vehicle operating condition constraints: real-time vehicle speed ≤ 15km / h, vehicle gear is N (neutral) or R (reverse), no motor braking feedback request, and discharge current < 30A; The triple constraint parameters support vehicle calibration adjustments, and the switching process is locked if any condition is not met.

3. The seamless switching control system for A+B dual lithium battery packs according to claim 1, characterized in that: The switch from main power supply from main battery pack A to main power supply from auxiliary battery pack B employs a four-step MOSFET hierarchical timing control, with the steps as follows: Step 1: The main battery A pack sends a command to turn off the charging MOSFET of the main battery A pack, cutting off the reverse charging path between the two packs; Step 2: Turn on the discharge MOSFET of auxiliary battery pack B to achieve short-term parallel transition power supply of battery packs A and B; Step 3: Turn off the discharge MOSFET of main battery A, disconnecting main battery A from the high-voltage power supply circuit; Step 4: During charging, turn on the charging MOSFET of auxiliary battery B to complete the power supply of auxiliary battery B. When switching from auxiliary battery B to main battery A, the switching logic is completely symmetrical, the steps are executed in reverse order, and the interval between all steps is ≤100ms.

4. The seamless switching control system for A+B dual lithium battery packs according to claim 1, characterized in that: The independent CAN communication module uses a TJA1051 transceiver. The CAN bus ID segment of the main battery pack A is 0x100~0x1FF, and the dedicated isolated CAN ID segment of the auxiliary battery pack B is 0x300~0x3FF. The dual CAN bus isolation architecture ensures that the peak bus network load is ≤22% and the message loss rate is <0.01%.

5. The seamless switching control system for A+B dual lithium battery packs according to claim 1, characterized in that: The A-pack BMS has built-in dual-pack collaborative charging control logic; after the charger is woken up, the A-pack BMS management unit detects the current main battery. If the current main battery is auxiliary battery pack B, then charge auxiliary battery pack B directly. If the current main battery is the main battery pack A and the SOC of the auxiliary battery pack B is greater than 80%, the main battery pack A will be automatically switched to the auxiliary battery pack B and then the auxiliary battery pack B will be charged. Under low-temperature charging conditions, the BMS management unit of package A sends a preheating command to the BMS management unit of package B to heat the generator cells.

6. The seamless switching control system for A+B dual lithium battery packs according to claim 1, characterized in that: The CAN communication ID segment of the auxiliary battery pack B is physically isolated from the main battery pack A, and the peak load of the dual-pack CAN bus is ≤25%.

7. A method for a seamless switching control system for A+B dual lithium battery packs, characterized in that: It includes the following steps: S1, the vehicle controller VCU and the A-package BMS management unit collect the dual-package power, SOC, vehicle speed, gear position, motor feedback status, and high-voltage discharge current in real time, and continuously verify the triple switching constraints. S2. After all three constraints are met, the vehicle controller (VCU) sends a coordinated control command to the motor controller (MCU) to turn off the motor energy feedback and limit the maximum discharge current of the motor. S3 and A package BMS management units issue charging and discharging MOSFET on / off commands in sequence according to the four-step hierarchical MOSFET timing sequence to complete the dual-package parallel transition and main power supply switching. S4. After all the switching processes are completed, the vehicle controller (VCU) removes the current limiting and feedback disabling restrictions of the motor controller (MCU) and restores the complete power output control of the motor. S5: Under charging conditions, it automatically selects the charging battery based on the dual-pack SOC and issues a preheating command for the auxiliary battery B pack cells in low-temperature environments.

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