Dual battery electrical system and method of controlling the same

Abstract

The application relates to the field of new energy automobile battery management technology, and discloses a double-battery-pack electrical system and a control method thereof. The method obtains state information of the double-battery-pack through a controller, determines a control strategy including working mode selection, fault protection judgment and energy balance judgment according to the state information and vehicle power demand, generates control instructions of each switching element and voltage regulating device and executes the control instructions according to a preset time sequence, and establishes a corresponding current path; when the battery pack is switched, the output voltage of the voltage regulating device is matched with the current voltage of the high-voltage output port, then the target battery pack is switched in and the current power supply battery pack is disconnected, and seamless switching under load is realized. The application can reduce voltage fluctuation when the battery pack is switched, balance energy between the battery packs, and meet the vehicle power demand during series charging.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle battery management technology, and in particular to a dual-battery pack electrical system and its control method. Background Technology

[0002] With the development of new energy vehicle technology, the range and charging efficiency of power batteries have become key factors restricting their widespread application. In order to improve the driving range and ease of use of vehicles, some new energy vehicles have begun to adopt a dual-battery pack configuration scheme to optimize the overall vehicle performance through reasonable power management.

[0003] However, existing dual-battery pack electrical systems have several shortcomings in their control methods. For example, some existing solutions switch the control switch module in series with the target battery pack and the charging interface to form a charging circuit when a low-voltage charging signal is detected at the charging interface; when a high-voltage charging signal is detected, the control switch module switches in series with the charging interface, the first battery pack, and the second battery pack to form a charging circuit. Other solutions adjust the connection relationship between the first and second battery packs through a control switch assembly, enabling conversion between parallel, series, and isolated connections. Still other solutions employ boost or buck converters to achieve charge and discharge control.

[0004] However, the aforementioned existing technologies are prone to significant voltage fluctuations during battery pack switching, affecting the stable operation of the vehicle's electrical equipment. Furthermore, these technologies lack effective energy balancing mechanisms between battery packs, leading to substantial differences in the state of charge between the two packs after long-term use, impacting the overall performance of the battery system. Moreover, during series charging, they cannot simultaneously meet the vehicle's power demands, resulting in a poor user experience.

[0005] Therefore, there is a need for a dual-battery pack electrical system control method that can achieve smooth switching of battery packs, balance energy between battery packs, and meet the requirements of various operating conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a dual-battery pack electrical system and its control method to solve the technical problems in the prior art, such as large voltage fluctuations during battery pack switching, lack of energy balancing means, and inability to meet the power demand of the whole vehicle during charging.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a control method for a dual-battery pack electrical system, applicable to a dual-battery pack electrical system including a first battery pack, a second battery pack, a high-voltage output port, a charging interface, a switching device, multiple unidirectional conducting elements, a voltage regulating device, and a controller. The switching device includes multiple switching elements for establishing different current paths. These multiple switching elements, based on their connection positions and control functions, include a positive electrode switching element, a negative electrode switching element, a first switching element, a ninth switching element, a tenth switching element, an energy recovery switching element, and an eighth switching element. The multiple unidirectional conducting elements are arranged in corresponding current paths to achieve unidirectional conduction. The voltage regulating device is used to regulate the voltage. The dual-battery pack electrical system control method includes the following steps: S1. Obtain the status information of the first battery pack and the second battery pack through the controller. The status information includes the state of charge, voltage, current and temperature. S2. Based on the status information and the vehicle's power demand, determine the control strategy. The control strategy includes working mode selection, fault protection judgment, and energy balance judgment. The working modes include series charging mode, individual discharge mode, switching mode, and energy recovery mode. S3. Generate control commands for each switching element and the voltage regulation device according to the control strategy; S4. The controller executes the control command to control each switching element to close or open according to a preset timing sequence, establishing a corresponding current path; when executing the switching mode, the controller controls the eighth switching element to connect the input terminal of the voltage regulating device to the target battery pack, adjusts the output voltage of the voltage regulating device to match the current voltage of the high voltage output port, and then closes the switching element corresponding to the target battery pack and disconnects the current power supply battery pack, completing seamless switching under load; S5. During the execution of the control strategy, continuously monitor the operating status of the first battery pack and the second battery pack. When a change in status is detected, return to step S2 to redetermine the control strategy.

[0008] In some implementations, before the target battery pack is connected to the high-voltage output port, the bus capacitor of the high-voltage output port is pre-charged, specifically as follows: The eighth switching element is controlled to connect the input terminal of the voltage regulating device to the target battery pack. The voltage regulating device obtains electrical energy from the target battery pack and gradually increases its output voltage until the output voltage reaches the terminal voltage of the target battery pack, thus completing the pre-charging of the bus capacitor. After pre-charging is completed, the voltage regulator switches to normal discharge mode and then executes the switching mode.

[0009] In some implementations, the switching mode employs a smooth switching method based on a voltage regulation device, which includes the following steps: S21. When the current power supply battery pack is switched to the target battery pack, the positive switch element, energy recovery switch element and negative switch element corresponding to the current power supply battery pack are kept closed, and the current power supply battery pack continues to supply power to the high voltage output port. S22. Disconnect the energy recovery switch element corresponding to the current power supply battery pack, control the eighth switch element to connect the input terminal of the voltage regulator to the target battery pack, start the voltage regulator, and obtain input electrical energy from the target battery pack by the voltage regulator; S23. Control the voltage regulator to gradually increase its output voltage; when the output voltage of the voltage regulator exceeds the terminal voltage of the current power supply battery pack, the voltage regulator shall take over the load current of the high voltage output port; S24. After a preset stabilization time, control the positive and negative switch elements corresponding to the target battery pack to close, so that the target battery pack supplies power to the high voltage output port. S25. Disconnect the input-side switching connection of the voltage regulator, disconnect the positive and negative switching elements corresponding to the current power supply battery pack, and close the energy recovery switching element corresponding to the target battery pack to complete the battery pack switching. During the switching process, the voltage fluctuation amplitude at the high-voltage output port is less than the preset voltage fluctuation threshold.

[0010] Specifically, the voltage regulating device is controlled through the following steps: S31. According to the target operating mode, the input terminal of the voltage regulation device is selected by the eighth switching element, the input terminal including the positive terminal of the second battery pack; S32. Detect the input voltage and output voltage of the voltage regulation device, and calculate the current conversion ratio; S33. According to the voltage demand of the high voltage output port, dynamically adjust the conversion ratio of the voltage regulation device to keep the output voltage within the target voltage range; S34. During the battery pack switching process, the output power of the voltage regulation device is adjusted to achieve a smooth power transition between the old and new power supply battery packs. The input terminal of the voltage regulator is connected to the positive charging terminal of the charging interface. The voltage regulator obtains electrical energy from the charging interface and supplies power to the high-voltage output port, so as to realize simultaneous charging and power consumption.

[0011] In some implementations, during the execution of the series charging mode, when the vehicle's power demand is detected, the eighth switching element is controlled to connect the input terminal of the voltage regulator to the positive terminal of the second battery pack. The voltage regulator then draws power from the positive terminal of the second battery pack to supply power to the high-voltage output port, thereby enabling simultaneous series charging and vehicle power consumption.

[0012] In some implementations, the series charging mode is performed by the following steps: S41. After detecting that the charging interface is connected to an external charging pile, determine the state of charge of the first battery pack and the second battery pack. S42. When the state of charge of the first battery pack and the second battery pack both support high-power charging, determine that the series charging mode is adopted, generate a series charging control command, and control the first switch element, the ninth switch element and the tenth switch element to close, while other switch elements are opened. S43. Establish a series charging circuit. The charging current flows from the positive terminal of the charging interface into the positive terminal of the first battery pack through the ninth switching element, flows out from the negative terminal of the first battery pack after passing through the first battery pack, flows into the positive terminal of the second battery pack through the first switching element and the unidirectional conducting element of the series path, flows out from the negative terminal of the second battery pack after passing through the second battery pack, and flows back to the negative terminal of the charging interface through the tenth switching element. S44. During the charging process, monitor the voltage and temperature of each battery pack in real time. When the voltage of any battery pack reaches the charging cutoff voltage or the temperature exceeds the preset safe temperature range, disconnect the first switching element and switch to the individual charging mode to continue charging only the battery packs that are not fully charged.

[0013] In some implementations, the individual discharge mode is performed by the following steps: S51. Calculate the availability score of each battery pack based on the state of charge, temperature and health status of the first and second battery packs. The availability score comprehensively considers the temperature adaptability, state of charge and health status of each battery pack under the current ambient temperature. S52. Select the battery pack with the higher score as the power supply battery pack; If the first battery pack scores high, then the corresponding positive electrode switch element, energy recovery switch element, and negative electrode switch element of the first battery pack are closed, and other discharge-related switch elements are opened. If the second battery pack scores higher, then the corresponding positive electrode switch, energy recovery switch, and negative electrode switch of the second battery pack will be closed, and other discharge-related switch elements will be opened. S53. Establish a corresponding discharge circuit. The current flows from the positive terminal of the power supply battery pack through the positive terminal switching element and the energy recovery switching element to the positive terminal output of the high voltage output port. After supplying power to the vehicle load, the current flows back from the negative terminal output of the high voltage output port through the negative terminal switching element to the negative terminal of the power supply battery pack. S54. During the discharge process, monitor the state of charge and temperature of the power supply battery pack in real time. When the state of charge is lower than the preset switching threshold or the temperature exceeds the preset safe temperature range, trigger the switching mode.

[0014] In some implementations, the energy recovery mode is performed through the following steps: S61. When a vehicle braking signal is detected, determine the current power supply battery pack; S62. If the current power supply is the first battery pack, an energy recovery control command for the first battery pack is generated to control the positive terminal switch element, energy recovery switch element and negative terminal switch element corresponding to the first battery pack to remain closed, establish an energy recovery circuit, and the braking energy flows from the positive terminal of the high voltage output port through the energy recovery switch element and the positive terminal switch element to the positive terminal of the first battery pack to charge the first battery pack. If the current power supply is the second battery pack, an energy recovery control command for the second battery pack is generated to control the corresponding positive terminal switch element, energy recovery switch element and negative terminal switch element of the second battery pack to remain closed, establish an energy recovery circuit, and the braking energy flows from the positive terminal of the high voltage output port through the energy recovery switch element and the positive terminal switch element to the positive terminal of the second battery pack to charge the second battery pack. S63. During the energy recovery process, monitor the recovery current and battery pack voltage in real time. When the battery pack voltage reaches the charging cutoff voltage or the recovery current drops below the preset current threshold, disconnect the corresponding energy recovery switching element and exit the energy recovery mode.

[0015] In some implementations, the triggering conditions for the switching mode include the current state of charge of the battery pack being lower than a preset switching threshold, the temperature of the current battery pack exceeding a preset safe temperature range, the current battery pack detecting a fault or a significant performance degradation, or receiving a manual switching command from the driver. When any of the above conditions are met, the switching process is initiated, switching from the current battery pack to another battery pack for power supply.

[0016] In some implementations, fault protection control is performed through the following steps: S81. Monitor the voltage, current and temperature of the first and second battery packs in real time to determine whether each parameter is within the normal range; S82. Fault protection is triggered when one of the following anomalies is detected: The battery pack voltage is lower than the preset lower limit voltage or higher than the preset upper limit voltage; The battery pack charging and discharging current exceeds the preset current safety threshold. The battery pack temperature is below the preset lower limit or above the preset upper limit. A short circuit or open circuit fault occurs in a unidirectional conducting element or a switching element; S83. Generate and execute corresponding protection control commands based on the fault type and the faulty battery pack: If the faulty battery pack is the currently powered battery pack, immediately initiate the switching process to switch to another battery pack for power supply. If the other battery pack is also faulty, disconnect all discharge switching components and stop power supply. If the faulty battery pack is a non-power supply battery pack, immediately isolate the battery pack and disconnect all switching components associated with the battery pack to prevent the fault from spreading. S84. Send a fault alarm signal to the vehicle controller and record the fault type, fault occurrence time, fault battery pack identifier and battery pack status information at that time. S85. Do not use the faulty battery pack before the fault is eliminated. Continuously monitor the fault status until the fault is resolved.

[0017] In some implementations, mutual charging control is performed through the following steps: S91. When the vehicle is stationary or in a low-power electrical state, periodically check the state of charge of the first and second battery packs. S92. Calculate the state of charge difference between the two battery packs. When the state of charge of the second battery pack is higher than that of the first battery pack and the difference is greater than the preset equalization threshold, start the inter-battery pack charging process. S93. Control the eighth switch element to close to connect the input terminal of the voltage regulator to the second battery pack, control the energy recovery switch element and negative switch element corresponding to the first battery pack to close, the voltage regulator converts the electrical energy of the second battery pack and flows through the energy recovery switch element and unidirectional conduction element to the positive terminal of the first battery pack, and after passing through the first battery pack, it forms a circuit from the negative terminal of the first battery pack through the negative switch element, so as to realize the charging of the first battery pack by the second battery pack. S94. During the mutual charging process between battery packs, monitor the difference in state of charge and charging current between the two battery packs in real time. When the difference in state of charge is less than the preset equalization threshold or the charging current drops below the preset current threshold, disconnect the corresponding switching element and end the mutual charging between battery packs.

[0018] In a second aspect, the present invention provides a dual-battery pack electrical system, comprising: The first positive terminal and the first negative terminal are used to connect the first battery pack; The second positive terminal and the second negative terminal are used to connect to the second battery pack; The high-voltage output port, including a positive output terminal and a negative output terminal, is used to supply power to the vehicle load; The charging interface includes a positive charging terminal and a negative charging terminal, used to connect to an external charging station; The switching device includes multiple switching elements for establishing different current paths between the first positive terminal, the first negative terminal, the second positive terminal, the second negative terminal, the high-voltage output port, and the charging interface; Multiple unidirectional conducting elements are placed in the corresponding current paths to achieve unidirectional conduction and reverse protection; A voltage regulation device includes an input terminal and an output terminal. The input terminal can be selectively connected to a first positive terminal and a second positive terminal via an eighth switching element. The output terminal is connected to a high-voltage output port for regulating voltage and assisting in battery pack switching. The controller includes a vehicle controller, a first battery management system, and a second battery management system. The controller is electrically connected to each switching element in the switching device and the voltage regulation device, and is used to execute the dual-battery pack electrical system control method as described above.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention achieves flexible control of the dual-battery pack system by acquiring real-time status information of the dual battery packs and determining control strategies based on the vehicle's power consumption needs. On one hand, when one battery pack malfunctions or has a low state of charge, it can promptly switch to the other battery pack for power supply, preventing the vehicle from losing power due to a single battery pack failure during operation and ensuring reliable vehicle operation. On the other hand, by establishing control strategies including operating mode selection, fault protection judgment, and energy balance judgment, it can flexibly select operating modes such as series charging, individual discharging, battery pack switching, or energy recovery according to different operating conditions, improving the system's adaptability. Furthermore, by generating control commands for switching elements and executing them according to a preset timing sequence, it can standardize the on / off actions of each switching element, establish different current paths, avoid the risk of short circuits or open circuits caused by misoperation, and continuously monitor the operating status and adjust the control strategy in a timely manner according to status changes. This closed-loop control mechanism enables the system to quickly respond to changes in the battery pack's status, ensuring the safety and reliability of the vehicle's power consumption.

[0020] The present invention has other features and advantages, which will be apparent from or will be set forth in detail in the accompanying drawings and the following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a circuit diagram of the dual-battery pack electrical system according to Embodiment 1 of the present invention.

[0023] Figure 2 This is a flowchart of the dual-battery pack electrical system control method according to Embodiment 1 of the present invention.

[0024] Figure 3 This is a schematic diagram of the current path in the pre-charge mode of Embodiment 1 of the present invention.

[0025] Figure 4 This is a schematic diagram of the current path in the single discharge mode of the first battery pack according to Embodiment 1 of the present invention.

[0026] Figure 5 This is a schematic diagram of the current path in the individual discharge mode of the second battery pack according to Embodiment 1 of the present invention.

[0027] Figure 6 This is a schematic diagram of the current path in the energy recovery mode of the first battery pack according to Embodiment 1 of the present invention.

[0028] Figure 7 This is a schematic diagram of the current path in the energy recovery mode of the second battery pack according to Embodiment 1 of the present invention.

[0029] Figure 8 This is a schematic diagram of the current path in the series charging mode of Embodiment 1 of the present invention.

[0030] Figure 9 This is a schematic diagram of the current path for series charging and simultaneous power supply to the entire vehicle in Embodiment 1 of the present invention.

[0031] Figure 10 This is a schematic diagram of the current path for battery pack load switching according to Embodiment 1 of the present invention.

[0032] Figure 11 This is a schematic diagram of the current path for mutual charging between battery packs according to Embodiment 1 of the present invention.

[0033] Explanation of reference numerals in the attached figures: F1, first fuse; F2, second fuse; K1, First switching element; K2, Second switching element; K3, Third switching element; K4, Fourth switching element; K5, Fifth switching element; K6, Sixth switching element; K7, Seventh switching element; K8, Eighth switching element; K9, Ninth switching element; K10, Tenth switching element; D1, First unidirectional conducting element; D2, Second unidirectional conducting element; D3, Third unidirectional conducting element; D4, Fourth unidirectional conducting element; D5, Fifth unidirectional conducting element; U1, voltage regulating device; SENSOR1, first current sensor; SENSOR2, ​​second current sensor; HV+, positive output terminal; HV-, negative output terminal; CHG+, positive charging terminal; CHG-, negative charging terminal; Pack1, first battery pack; Pack1+, first positive terminal; Pack1-, first negative terminal; Pack2, second battery pack; Pack2+, second positive terminal; Pack2-, second negative terminal; IN+ is the positive input terminal of the voltage regulator; IN- is the negative input terminal of the voltage regulator. OUT+ is the positive output terminal of the voltage regulator; OUT- is the negative output terminal of the voltage regulator. Detailed Implementation

[0034] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this invention in detail, the following description, in conjunction with the listed specific embodiments and accompanying drawings, provides a detailed explanation. The embodiments described herein are merely illustrative of the technical solutions of this invention and are therefore intended only as examples, not as limiting the scope of protection of this invention.

[0035] Example 1 Please see Figure 1 The dual-battery electrical system of this embodiment includes a first battery pack Pack1, a second battery pack Pack2, a high-voltage output port, a charging interface, a switching device, multiple unidirectional conducting elements, a voltage regulating device U1, and a controller.

[0036] The positive terminal of the first battery pack Pack1 is connected to the switching device via the first fuse F1, and its negative terminal is connected to the switching device via the first current sensor SENSOR1.

[0037] The positive terminal of the second battery pack Pack2 is connected to the switching device via the second fuse F2, and its negative terminal is connected to the switching device via the second current sensor SENSOR2.

[0038] The high-voltage output port includes a positive output terminal HV+ and a negative output terminal HV-, which are used to supply power to the vehicle load.

[0039] The charging interface includes a positive charging terminal CHG+ and a negative charging terminal CHG-, which are used to connect to an external charging station.

[0040] The switching device includes a first switching element K1 to a tenth switching element K10, wherein the positive switching element includes a fourth switching element K4 and a sixth switching element K6, the negative switching element includes a third switching element K3 and a second switching element K2, the first switching element K1 is connected in series, the ninth switching element K9 is connected to the positive charging terminal, the tenth switching element K10 is connected to the negative charging terminal, the fifth switching element K5 and the seventh switching element K7 are connected to the energy recovery switching element, and the eighth switching element K8 is connected to the input switching switching element.

[0041] The plurality of unidirectional conducting elements include a first unidirectional conducting element D1 to a fifth unidirectional conducting element D5. The first unidirectional conducting element D1 is disposed in a series path; the second unidirectional conducting element D2 and the fourth unidirectional conducting element D4 are disposed in the forward discharge paths of the first battery pack Pack1 and the second battery pack Pack2, respectively; the third unidirectional conducting element D3 is connected in parallel with the second unidirectional conducting element D2 in reverse, used to allow current to flow unidirectionally from the second positive terminal Pack2+ to the first positive terminal Pack1+ when the battery packs are mutually charged; the fifth unidirectional conducting element D5 is connected in parallel with the fourth unidirectional conducting element D4 in reverse, used to prevent external current from flowing back into the second positive terminal Pack2+; the first unidirectional conducting elements D1 to the fifth unidirectional conducting elements D5 are used to implement unidirectional conduction and reverse protection, respectively.

[0042] The voltage regulator U1 is a unidirectional converter. Its input terminal is connected to the positive terminal of the second battery pack Pack2 via the input switching element K8, its negative input terminal is connected to the negative terminal of the second battery pack Pack2, and its output terminal is connected to the high-voltage output port. It can be understood that the voltage regulator U1 can be installed inside the battery pack or on the vehicle itself. When installed on the vehicle, it connects to the four ports of the voltage regulator U1. Of course, the voltage regulator U1 can also be a bidirectional converter, depending on the requirements.

[0043] The operating modes of this embodiment are categorized into three types based on function: charging, discharging, and mutual charging. Among them, the charging type includes charging the first battery pack Pack1 alone, charging the second battery pack Pack2 alone, charging the two battery packs in series, and switching to charging the incomplete battery pack after either battery pack is fully charged during the series charging process.

[0044] The discharge category includes the individual discharge of the first battery pack Pack1, the individual discharge of the second battery pack Pack2, energy recovery during the discharge process, and battery pack load switching, among which energy recovery is a sub-stage in the discharge process.

[0045] The mutual charging type refers to the charging of the first battery pack, Pack 1, by the second battery pack Pack 2. Specifically, the second battery pack Pack 2 has a larger capacity than the first battery pack Pack 1. Specifically, the second battery pack Pack 2 can be a lithium-ion battery, while the first battery pack Pack 1 can be a sodium-ion battery, which has better low-temperature performance and is preferred for use in cold regions.

[0046] It is worth noting that when the voltage regulating device U1 is a unidirectional converter, the input side is fixed on one side and the output side is fixed on the other side. Under this structure, the system can achieve individual charging and series charging, but cannot achieve parallel charging. If the voltage regulating device U1 is replaced with a bidirectional converter, that is, with the original output side as the input and the original input side as the output in the reverse direction, then parallel charging can be achieved. This embodiment uses a unidirectional converter for explanation.

[0047] Please see Figure 2 The control method for the dual-battery pack electrical system includes the following steps: S1. Obtain the status information of the first battery pack Pack1 and the second battery pack Pack2 through the controller. The status information includes the state of charge, voltage, current and temperature.

[0048] The controller includes a vehicle controller, a first battery management system, and a second battery management system. The first battery management system collects the voltage and temperature of the first battery pack Pack1 and obtains its current through the first current sensor SENSOR1. The second battery management system collects the voltage and temperature of the second battery pack Pack2 and obtains its current through the second current sensor SENSOR2. Each battery management system estimates the state of charge of its corresponding battery pack and reports it to the vehicle controller.

[0049] S2. Based on the status information and the vehicle's power demand, determine the control strategy. The control strategy includes operating mode selection, fault protection judgment, and energy balance judgment. The operating modes include series charging mode, individual discharge mode, switching mode, and energy recovery mode.

[0050] Understandably, the operating mode selection is based on the current charging and discharging requirements, the state of charge of each battery pack, and the temperature, and the target operating mode is determined from the above operating modes.

[0051] The fault protection judgment is based on whether the voltage, current, and temperature of each battery pack exceed the limit, and whether the switching elements and unidirectional conduction elements are short-circuited or open-circuited, to determine whether to enter the fault protection.

[0052] The energy balance judgment is based on whether the difference in the state of charge of the two battery packs exceeds a preset equalization threshold to determine whether to start mutual charging between the battery packs.

[0053] S3. Based on the control strategy, generate control commands for each switching element and the voltage regulating device. The control commands include the on / off state and on / off sequence of each switching element, as well as the start / stop commands, output voltage target value, and output power limit value of the voltage regulating device U1.

[0054] S4. The controller executes the control command to control each switching element to close or open according to a preset timing sequence, establishing a corresponding current path; when executing the switching mode, the input switching element is controlled to connect the input terminal of the voltage regulator to the target battery pack, the output voltage of the voltage regulator is adjusted to match the current voltage of the high voltage output port, and then the switching element corresponding to the target battery pack is closed and the current power supply battery pack is disconnected, completing the seamless switching under load.

[0055] Please see Figure 10 The controller first controls the input switching element K8 to connect the input terminal of the voltage regulator U1 to the target battery pack. U1 then adjusts the output voltage to match the current voltage of the high voltage output port. Next, it closes the positive switch element corresponding to the target battery pack and opens the positive switch element corresponding to the current power supply battery pack. U1 takes over the load current at the moment of switching to prevent the bus voltage from dropping.

[0056] S5. During the execution of the control strategy, continuously monitor the operating status of the first battery pack Pack1 and the second battery pack Pack2. When a change in status is detected, return to step S2 to redetermine the control strategy.

[0057] Specifically, the monitoring content mentioned here includes the state of charge, voltage, current, temperature and execution status of the current working mode of each battery pack. When the state of charge, load demand or fault status changes, the process returns to step S2 to form a closed-loop control.

[0058] Before the target battery pack is connected to the high-voltage output port, the bus capacitor of the high-voltage output port can be pre-charged. Please refer to [link / reference]. Figure 3 The input switching element K8 controls the input terminal of the voltage regulating device U1 to connect to the target battery pack. The voltage regulating device U1 obtains electrical energy from the target battery pack and gradually increases its output voltage until the output voltage reaches the terminal voltage of the target battery pack, thus completing the pre-charging of the bus capacitor.

[0059] After pre-charging is completed, the voltage regulating device U1 switches to normal discharge mode and then executes the switching mode.

[0060] It is understandable that the voltage regulation device U1, with its built-in current limiting function, limits the charging current of the bus capacitor, precisely controlling the charging current and preventing damage to the equipment from a sudden surge of large current during charging. Compared to traditional resistor pre-charging schemes, this avoids the power loss and heat generation problems associated with pre-charging resistors, and the pre-charging current can be flexibly configured according to the capacitor capacity and system requirements, making it more adaptable. Furthermore, after pre-charging is complete, the positive terminal switch element corresponding to the target battery pack is closed, and then the input switching switch element K8 is opened, avoiding the generation of an electric arc by directly opening the input switching switch element K8 under load. It should be noted that this application uses the voltage regulation device U1 to pre-charge the bus capacitor at the high-voltage output port, eliminating the need for a separate pre-charging circuit and simplifying the overall circuit.

[0061] Furthermore, the switching mode employs a smooth switching method based on a voltage regulation device; please refer to [link to relevant documentation]. Figure 10 Taking the first battery pack Pack1 as the current power supply battery pack and the second battery pack Pack2 as the target battery pack as an example, the steps include the following: S21. When the current power supply battery pack is switched to the target battery pack, the positive switch element, energy recovery switch element and negative switch element corresponding to the current power supply battery pack are kept closed, and the current power supply battery pack continues to supply power to the high voltage output port. Understandably, at this time, the fourth switch element K4, the fifth switch element K5, and the third switch element K3 corresponding to the first battery pack Pack1 remain closed. The current flows from the positive terminal of the first battery pack Pack1 through the first fuse F1, the fourth switch element K4, and the fifth switch element K5 to the positive output terminal HV+. After supplying power to the load, the current flows from the negative output terminal HV- through the third switch element K3 and the first current sensor SENSOR1 back to the negative terminal of the first battery pack Pack1.

[0062] S22. Disconnect the energy recovery switch element corresponding to the current power supply battery pack, control the input switching switch element to connect the input terminal of the voltage regulation device to the target battery pack, start the voltage regulation device, and obtain input electrical energy from the target battery pack by the voltage regulation device.

[0063] First, disconnect the fifth switching element K5, then close the input switching element K8, connecting the input terminal of the voltage regulator U1 to the positive terminal of the second battery pack Pack2, allowing U1 to draw power from Pack2. After the fifth switching element K5 is disconnected, the first battery pack Pack1 continues to supply power briefly via the second unidirectional conducting element D2, and can be naturally cut off by D2 when the output voltage of U1 increases.

[0064] S23. Control the voltage regulator to gradually increase its output voltage; when the output voltage of the voltage regulator exceeds the terminal voltage of the current power supply battery pack, the current power supply battery pack automatically stops supplying power due to the natural cut-off action of the unidirectional conducting element, and the voltage regulator takes over the load current of the high voltage output port.

[0065] Understandably, when the output voltage of U1 exceeds the terminal voltage of the first battery pack Pack1, the unidirectional conducting element D2 of the forward discharge path of the first battery pack Pack1 will naturally be cut off due to the reverse voltage, and the first battery pack Pack1 will automatically disconnect from the power supply. The load current will then be supplied by U1 through its output terminal, thus completing the power supply transition without interrupting the power supply.

[0066] S24. After a preset stabilization time, the positive and negative switching elements corresponding to the second battery pack Pack2 are closed, allowing the second battery pack Pack2 to supply power to the high-voltage output port through the voltage regulation device. The preset stabilization time can be 10-100ms.

[0067] After a delay until the output of U1 stabilizes, the positive switch element K6 and the negative switch element K2 corresponding to the second battery pack Pack2 are closed, and the second battery pack Pack2 supplies power to the high-voltage output port through the unidirectional conduction element D4 of its forward discharge path.

[0068] S25. Disconnect the input-side switching connection of the voltage regulator, disconnect the positive and negative switching elements corresponding to the current power supply battery pack, and close the energy recovery switching element corresponding to the target battery pack to complete the battery pack switching. That is, disconnect the input switching element K8, disconnect the fourth switching element K4 and the third switching element K3 corresponding to the first battery pack Pack1, and then close the seventh switching element K7, so that the second battery pack Pack2 forms a direct power supply circuit through the sixth switching element K6, the seventh switching element K7 and the second switching element K2.

[0069] After the switching is completed, the seventh switching element K7 bypasses the fourth unidirectional conducting element D4 to reduce the supply voltage drop, and the fifth unidirectional conducting element D5 is used to prevent external current from flowing back into the second positive terminal Pack2+.

[0070] When switching from the second battery pack Pack2 to the first battery pack Pack1 in reverse, keep the sixth switch element K6, the seventh switch element K7, and the second switch element K2 closed; first, open the seventh switch element K7, then close the eighth switch element K8 and let the voltage regulator U1 take over the load current; then close the fourth switch element K4 and the third switch element K3, open the eighth switch element K8, the sixth switch element K6, and the second switch element K2, and finally close the fifth switch element K5 to complete the load switching from the second battery pack Pack2 to the first battery pack Pack1.

[0071] It is understood that during the switching process, the voltage regulation device U1 bears the load current throughout and levels the voltage of the old and new battery packs, and the voltage fluctuation amplitude at the high voltage output port is less than the preset voltage fluctuation threshold.

[0072] During the aforementioned switching and power supply process, the voltage regulation device is controlled through the following steps: S31. According to the target operating mode, select the input terminal of the voltage regulation device by input switching element, wherein the input terminal includes the positive terminal of the second battery pack Pack2.

[0073] It is understood that in this circuit, the input terminal of the voltage regulating device U1 is connected to the positive terminal of the second battery pack Pack2 via the input switching element K8, and its negative input terminal is connected to the negative terminal of the second battery pack Pack2.

[0074] S32. Detect the input voltage and output voltage of the voltage regulation device, and calculate the current conversion ratio.

[0075] That is, the voltage at the input and output terminals of U1 is sampled, and the ratio of the output voltage to the input voltage is used as the current conversion ratio.

[0076] S33. Based on the voltage requirements of the high-voltage output port, dynamically adjust the conversion ratio of the voltage regulation device to keep the output voltage within the target voltage range.

[0077] That is, the duty cycle of U1 is adjusted according to the voltage demand of the high voltage output port to change its conversion ratio, so that the output voltage is maintained within the target voltage range.

[0078] S34. During the battery pack switching process, the output power of the voltage regulation device is adjusted to achieve a smooth power transition between the old and new power supply battery packs.

[0079] That is, gradually adjust the output power of U1 to smoothly transfer the load current between the original power supply battery pack, U1 and the new power supply battery pack, and avoid voltage fluctuations caused by sudden power changes.

[0080] Furthermore, during the execution of the series charging mode, when the vehicle's power demand is detected, the input switching element corresponding to the second battery pack Pack2 is controlled to connect the input terminal of the voltage regulating device to the positive terminal of the second battery pack Pack2, that is, the midpoint of the series charging circuit. The voltage regulating device draws power from the midpoint of the series circuit and supplies power to the high-voltage output port, so as to realize the simultaneous occurrence of series charging and vehicle power consumption.

[0081] Please see Figure 9 The positive terminal of the second battery pack Pack2 is the midpoint of the series connection between the negative terminal of the first battery pack Pack1 and the positive terminal of the second battery pack Pack2 in the series circuit. The voltage regulating device U1 draws power from this midpoint of the series connection and supplies power to the high-voltage output port through its output terminal. This power supply circuit is connected in parallel with the second battery pack Pack2, has the same function but a different path, and the power supply voltage is regulated by the voltage regulating device U1, so that the voltage tolerance requirements of the high-voltage components of the vehicle are not increased due to the increase in series charging voltage.

[0082] As another implementation method for simultaneous series charging and power supply, it can also be achieved through a direct power supply branch without the aforementioned voltage regulation device. Please refer to... Figure 9 Based on the series charging circuit, the positive terminal switch element K4 and the negative terminal switch element K3 corresponding to the first battery pack Pack1 are further closed to form a direct power supply branch connected in parallel with the first battery pack Pack1. The specific current flow is as follows: A portion of the charging current flows from the positive terminal CHG+ through the positive terminal connection switch element K9, the positive terminal switch element K4, and the unidirectional conduction element D2 of the forward discharge path of the first battery pack Pack1 to the positive output terminal HV+. After supplying power to the vehicle load, it flows from the negative output terminal HV- through the negative terminal switch element K3, the series connection switch element K1, the unidirectional conduction element D1 of the series path, and the second fuse F2 into the second battery pack Pack2. It then flows back to the negative terminal CHG- through the second battery pack Pack2, the second current sensor SENSOR2, ​​and the negative terminal connection switch element K10. This direct power supply branch and the series charging circuit coexist.

[0083] Please see Figure 8 The series charging mode is executed through the following steps: S41. After detecting that the charging interface is connected to an external charging pile, determine the state of charge of the first battery pack Pack1 and the second battery pack Pack2.

[0084] That is, after the vehicle controller detects the connection of an external charging pile through the charging interface, it reads the state of charge reported by the first battery management system and the second battery management system.

[0085] S42. When the state of charge of the first battery pack Pack1 and the second battery pack Pack2 both support high-power charging, the series charging mode is determined to be adopted, a series charging control command is generated, and the series connection switching element, the charging positive terminal connection switching element and the charging negative terminal connection switching element are closed, while other switching elements are opened.

[0086] That is, the series-connected switching element K1, the positive charging connection switching element K9, and the negative charging connection switching element K10 are closed, while the remaining switching elements are open.

[0087] S43. Establish a series charging circuit. The charging current flows from the positive terminal of the charging interface through the positive terminal connection switch element into the positive terminal of the first battery pack Pack1. After passing through the first battery pack Pack1, it flows out from the negative terminal of the first battery pack Pack1. It then flows into the positive terminal of the second battery pack Pack2 through the series connection switch element and the unidirectional conduction element of the series path. After passing through the second battery pack Pack2, it flows out from the negative terminal of the second battery pack Pack2 and flows back to the negative terminal of the charging interface through the negative terminal connection switch element.

[0088] Specifically, please refer to Figure 8 The charging current flows from the positive terminal CHG+ through the positive terminal connection switch element K9 and the first fuse F1 into the positive terminal of the first battery pack Pack1. After passing through the first battery pack Pack1, it flows from its negative terminal through the first current sensor SENSOR1, the series connection switch element K1, the unidirectional conducting element D1 in the series path, and the second fuse F2 into the positive terminal of the second battery pack Pack2. After passing through the second battery pack Pack2, it flows from its negative terminal through the second current sensor SENSOR2 and the negative terminal connection switch element K10 back to the negative terminal CHG-.

[0089] S44. During the charging process, monitor the voltage and temperature of each battery pack in real time. When the voltage of any battery pack reaches the charging cutoff voltage or the temperature exceeds the preset safe temperature range, disconnect the series connection switching element and switch to individual charging mode to continue charging only the battery pack that is not fully charged.

[0090] That is, when the voltage of any battery pack reaches the charging cutoff voltage or the temperature exceeds the limit, the series connection switch element K1 is disconnected, and the system switches to individual charging mode, continuing to charge only the battery packs that are not fully charged.

[0091] Please see Figure 4 and Figure 5 The individual discharge mode is executed through the following steps: S51. Based on the state of charge, temperature, and health status of the first battery pack Pack1 and the second battery pack Pack2, calculate the availability score for each battery pack. The availability score comprehensively considers the temperature adaptability, state of charge, and battery health status of each battery pack under the current ambient temperature.

[0092] It is understandable that, taking the dual heterogeneous battery scheme with the first battery pack Pack1 being a sodium-ion battery and the second battery pack Pack2 being a lithium iron phosphate battery as an example, under low-temperature conditions (below 0°C in this embodiment), the low-temperature charge and discharge performance of the sodium-ion battery is significantly better than that of the lithium iron phosphate battery, and the controller preferentially selects the first battery pack Pack1 for power supply. Under normal temperature conditions, it preferentially selects the second battery pack Pack2 with a larger capacity for power supply.

[0093] The availability score can be obtained by weighting the above factors, and temperature adaptability reflects the charge and discharge capability of each battery pack's chemical system at the current temperature.

[0094] S52. Select the battery pack with the higher score as the power supply battery pack. If the first battery pack Pack1 has a higher score, control the fourth switch element K4, the fifth switch element K5 and the third switch element K3 to close, and other discharge-related switch elements to open; if the second battery pack Pack2 has a higher score, control the sixth switch element K6, the seventh switch element K7 and the second switch element K2 to close, and other discharge-related switch elements to open.

[0095] S53. Establish a corresponding discharge circuit. The current flows from the positive terminal of the power supply battery pack through the positive terminal switch element and the energy recovery switch element to the positive terminal of the high voltage output port. After supplying power to the vehicle load, the current flows back from the negative terminal of the high voltage output port through the negative terminal switch element to the negative terminal of the power supply battery pack.

[0096] Specifically, taking the first battery pack Pack1 as an example, when the fourth switch element K4, the fifth switch element K5 and the third switch element K3 are closed, the current flows from the positive terminal of the first battery pack Pack1 through the first fuse F1, the fourth switch element K4 and the fifth switch element K5 to the positive output terminal HV+, and after passing through the load, it flows from the negative output terminal HV- through the third switch element K3 and the first current sensor SENSOR1 back to the negative terminal of the first battery pack Pack1.

[0097] When the second battery pack Pack2 is powered, the sixth switch element K6, the seventh switch element K7 and the second switch element K2 are closed. The current flows from the positive terminal of the second battery pack Pack2 through the second fuse F2, the sixth switch element K6 and the seventh switch element K7 to the positive output terminal HV+. After passing through the load, the current flows from the negative output terminal HV- through the second switch element K2 and the second current sensor SENSOR2 back to the negative terminal of the second battery pack Pack2.

[0098] S54. During the discharge process, the state of charge and temperature of the power supply battery pack are monitored in real time. When the state of charge is lower than the preset switching threshold or the temperature exceeds the preset safe temperature range, the switching mode is triggered. After triggering the switching mode, the load is switched to another battery pack for power supply according to the aforementioned steps S21 to S25.

[0099] Please see Figure 6 and Figure 7 The energy recovery mode is a sub-stage in the discharge process, and is executed through the following steps: S61. When a vehicle braking signal is detected, determine the current power supply battery pack.

[0100] S62. If the first battery pack Pack1 is currently powered, an energy recovery control command for the first battery pack Pack1 is generated. The fourth switch element K4, the fifth switch element K5, and the third switch element K3 are kept closed, while the other switch elements are opened. The braking energy flows from the positive output terminal HV+ through the fifth switch element K5 and the fourth switch element K4 to the positive terminal of the first battery pack Pack1. After passing through the first battery pack Pack1, it flows from its negative terminal through the first current sensor SENSOR1 and the third switch element K3 back to the negative output terminal HV-, thus charging the first battery pack Pack1. If the current power supply is the second battery pack Pack2, an energy recovery control command for the second battery pack Pack2 is generated, keeping the sixth switch element K6, the seventh switch element K7, and the second switch element K2 closed, while the other switches are open. The braking energy flows from the positive output terminal HV+ through the seventh switch element K7 and the sixth switch element K6 to the positive terminal of the second battery pack Pack2, and then from the negative terminal of the second battery pack Pack2 through the second current sensor SENSOR2 and the second switch element K2 back to the negative output terminal HV-, thus charging the second battery pack Pack2.

[0101] Specifically, during energy recovery in the first battery pack (Pack1), the fourth switch element K4, the fifth switch element K5, and the third switch element K3 remain closed, and the recovery current does not flow through the third unidirectional conducting element D3. During energy recovery in the second battery pack (Pack2), the sixth switch element K6, the seventh switch element K7, and the second switch element K2 remain closed, and the recovery current does not flow through the fifth unidirectional conducting element D5. Thus, individual discharge and energy recovery share the same direct-flow branch, reducing the voltage drop caused by the unidirectional conducting element.

[0102] S63. During the energy recovery process, monitor the recovery current and battery pack voltage in real time. When the battery pack voltage reaches the charging cutoff voltage or the recovery current drops below the preset current threshold, disconnect the corresponding energy recovery switching element and exit the energy recovery mode.

[0103] Specifically, the triggering conditions for the switching mode include the current state of charge of the battery pack being lower than a preset switching threshold, the temperature of the current battery pack exceeding a preset safe temperature range, the current battery pack detecting a fault or a significant performance degradation, and receiving a manual switching command from the driver. When any of the above conditions are met, the switching process is initiated, switching from the current battery pack to another battery pack for power supply.

[0104] The fault protection control is performed through the following steps: S81. Monitor the voltage, current and temperature of the first battery pack Pack1 and the second battery pack Pack2 in real time, and determine whether each parameter is within the normal range.

[0105] S82. When one of the following abnormalities is detected, such as the battery pack voltage being lower than the preset lower limit voltage or higher than the preset upper limit voltage, the battery pack charging / discharging current exceeding the preset current safety threshold, the battery pack temperature being lower than the preset lower limit temperature or higher than the preset upper limit temperature, or a short circuit or open circuit fault occurring in the unidirectional conducting element or switching element, the fault protection is triggered.

[0106] S83. Generate and execute corresponding protection control commands based on the fault type and the faulty battery pack: If the faulty battery pack is the currently powered battery pack, immediately initiate the battery pack switching process to switch to another battery pack for power supply. If the other battery pack is also faulty, disconnect all discharge switching components and stop power supply. If the faulty battery pack is a non-powered battery pack, immediately isolate the battery pack and disconnect all switching components associated with the battery pack to prevent the fault from spreading.

[0107] S84. Send a fault alarm signal to the vehicle controller and record the fault type, fault occurrence time, fault battery pack identifier, and battery pack status information at that time.

[0108] S85. Do not use the faulty battery pack before the fault is eliminated. Continuously monitor the fault status until the fault is resolved.

[0109] Please see Figure 11 The inter-pack charging control is performed through the following steps: S91. When the vehicle is stationary or in a low-power state, periodically check the state of charge of the first battery pack Pack1 and the second battery pack Pack2.

[0110] S92. Calculate the state of charge difference between the two battery packs. When the state of charge of the second battery pack Pack2 is higher than that of the first battery pack Pack1 and the difference is greater than the preset equalization threshold, start the inter-battery pack charging process.

[0111] S93. Control the input switching element to close to connect the input terminal of the voltage regulator to the second battery pack Pack2, control the energy recovery switching element and negative terminal switching element corresponding to the first battery pack Pack1 to close, the voltage regulator converts the electrical energy of the second battery pack Pack2 and then flows to the positive terminal of the first battery pack Pack1 through the energy recovery switching element and the unidirectional conduction element, and then forms a circuit from the negative terminal of the first battery pack Pack1 through the negative terminal switching element, so as to realize the charging of the first battery pack Pack1 by the second battery pack Pack2.

[0112] Specifically, please refer to Figure 11 Close the input switching element K8 to connect the input terminal of the voltage regulator U1 to the positive terminal of the second battery pack Pack2, and connect the negative input terminal of U1 to the negative terminal of the second battery pack Pack2. Close the energy recovery switching element K5 and the negative terminal switching element K3 corresponding to the first battery pack Pack1. After U1 converts the electrical energy of the second battery pack Pack2, it flows from its output terminal through the energy recovery switching element K5 and the third unidirectional conducting element D3 of the mutual charging path to the positive terminal of the first battery pack Pack1. After passing through the first battery pack Pack1, it forms a loop from its negative terminal through the negative terminal switching element K3 and the negative output terminal of U1.

[0113] The voltage regulating device U1 is connected to the side of the second battery pack Pack2 with a larger capacity. When the voltage of the first battery pack Pack1 is higher than that of the second battery pack Pack2, U1 boosts the voltage for charging. When the voltage of the first battery pack Pack1 is lower than that of the second battery pack Pack2, U1 depresses the voltage for charging. Regardless of which battery pack has a larger capacity, the second battery pack Pack2 charges the first battery pack Pack1.

[0114] S94. During the mutual charging process between battery packs, monitor the difference in state of charge and charging current between the two battery packs in real time. When the difference in state of charge is less than the preset equalization threshold or the charging current drops below the preset current threshold, disconnect the corresponding switching element and end the mutual charging between battery packs.

[0115] To better understand the various operating modes of this embodiment, the table below summarizes the operating states of the switching elements that need to be closed, the unidirectional conducting elements that need to be turned on, and the voltage regulating device in each mode. Switching elements not listed are all in the open state.

[0116] The voltage regulator U1 can be reused in pre-charge mode, switching mode, series charging simultaneous power supply mode and mutual charging mode, without the need to set up an additional independent pre-charge circuit, switching auxiliary circuit or equalization circuit, which reduces the number of system components, reduces system cost and size, and improves integration.

[0117] Example 2 Please see Figure 1 Example 1 describes the system's workflow from a control method perspective. This example will describe the control method for the dual-battery pack electrical system described in Example 1 from a hardware structure perspective. The dual-battery pack electrical system of this example includes a first positive terminal Pack1+, a first negative terminal Pack1-, a second positive terminal Pack2+, a second negative terminal Pack2-, a high-voltage output port, a charging interface, a switching device, multiple unidirectional conducting elements, a voltage regulating device U1, and a controller.

[0118] The first positive terminal Pack1+ and the first negative terminal Pack1- are used to connect to the first battery pack Pack1. The positive terminal of the first battery pack Pack1 is connected to the switching device via the first fuse F1, and its negative terminal is connected to the switching device via the first current sensor SENSOR1.

[0119] The second positive terminal Pack2+ and the second negative terminal Pack2- are used to connect the second battery pack Pack2. The positive terminal of the second battery pack Pack2 is connected to the switching device via the second fuse F2, and its negative terminal is connected to the switching device via the second current sensor SENSOR2.

[0120] The high-voltage output port includes a positive output terminal HV+ and a negative output terminal HV-, which are used to supply power to the vehicle load.

[0121] The charging interface includes a positive charging terminal CHG+ and a negative charging terminal CHG-, which are used to connect to an external charging station.

[0122] The switching device includes multiple switching elements for establishing different current paths between the first positive terminal Pack1+, the first negative terminal Pack1-, the second positive terminal Pack2+, the second negative terminal Pack2-, the high-voltage output port, and the charging interface.

[0123] Among them, the positive switch element K4 corresponding to the first battery pack Pack1 is connected between the first fuse F1 and the unidirectional conduction element D2 of the positive discharge path of the first battery pack Pack1, and the negative switch element K3 is connected between the first current sensor SENSOR1 and the negative output terminal HV-.

[0124] The positive switch element K6 corresponding to the second battery pack Pack2 is connected between the second fuse F2 and the unidirectional conducting element D4 of the positive discharge path of the second battery pack Pack2, and the negative switch element K2 is connected between the second current sensor SENSOR2 and the negative output terminal HV-.

[0125] A series-connected switching element K1 is connected between the first current sensor SENSOR1 and the unidirectional conducting element D1 in the series path. The other end of the unidirectional conducting element D1 is connected between the second fuse F2 and the second positive terminal Pack2+.

[0126] The positive charging connection switch element K9 is connected between the positive charging terminal CHG+ and the first fuse F1, and the negative charging connection switch element K10 is connected between the negative charging terminal CHG- and the second negative terminal Pack2-.

[0127] The fifth switching element K5 of the first battery pack Pack1 is connected between the positive output terminal HV+ and the common connection node of the fourth switching element K4 and the third unidirectional conduction element D3; the seventh switching element K7 of the second battery pack Pack2 is connected between the positive output terminal HV+ and the common connection node of the sixth switching element K6 and the fifth unidirectional conduction element D5.

[0128] The multiple unidirectional conducting elements are arranged in corresponding current paths to achieve unidirectional conduction and reverse protection. Specifically, unidirectional conducting elements D2 and D4 provide forward discharge paths for the first battery pack Pack1 and the second battery pack Pack2, respectively, when the fifth switching element K5 or the seventh switching element K7 is disconnected. The third unidirectional conducting element D3 ensures unidirectional current flow to the first positive terminal Pack1+ when the second battery pack Pack2 is mutually charging the first battery pack Pack1. The fifth unidirectional conducting element D5 prevents external current from flowing back into the second positive terminal Pack2+. The first unidirectional conducting element D1 ensures unidirectional series charging current flow to the second positive terminal Pack2+. Thus, the parallel design of unidirectional conducting elements D2 / D4 with the fifth switching element K5 / seventh switching element K7 not only allows for a shared direct path in individual discharge and energy recovery modes, reducing conduction losses of the unidirectional conducting elements, but also enables seamless transition between the two battery packs during switching by utilizing the natural cut-off effect of the unidirectional conducting elements, eliminating the need for additional current detection and active control, thereby improving switching reliability.

[0129] The voltage regulation device U1 includes an input positive terminal IN+, an input negative terminal IN-, an output positive terminal OUT+, and an output negative terminal OUT-. The input positive terminal IN+ can be selectively connected to the outside of the first fuse F1 (i.e., the side corresponding to the first positive terminal Pack1+) and the outside of the second fuse F2 (i.e., the side corresponding to the second positive terminal Pack2+) through an input switching element K8.

[0130] The negative input terminal IN- is connected between the second current sensor SENSOR2 and the second negative terminal Pack2-. The positive output terminal OUT+ is connected to the positive output terminal HV+, and the negative output terminal OUT- is connected to the negative output terminal HV-. This is used to adjust the voltage and assist in battery pack switching.

[0131] The controller includes a vehicle controller, a first battery management system, and a second battery management system. The controller is electrically connected to each switching element in the switching device and the voltage regulating device U1, and is used to execute the dual-battery pack electrical system control method as described in Embodiment 1.

[0132] Combination Figures 1-11 This invention achieves flexible control of the dual-battery pack system by acquiring the status information of the dual battery packs in real time and determining the control strategy according to the vehicle's power demand. On the one hand, when one battery pack malfunctions or has a low state of charge, it can switch to the other battery pack in a timely manner to prevent the vehicle from losing power due to a single battery pack failure during driving, thus ensuring the reliable operation of the vehicle. On the other hand, by establishing a control strategy that includes operating mode selection, fault protection judgment, and energy balance judgment, it can flexibly select operating modes such as series charging, individual discharging, battery pack switching, or energy recovery according to different operating conditions, improving the system's adaptability. Furthermore, by generating control commands for switching elements and executing them according to a preset timing sequence, it can standardize the on / off actions of each switching element, establish different current paths, avoid the risk of short circuits or open circuits caused by misoperation, and continuously monitor the operating status and adjust the control strategy in a timely manner according to the status changes. This closed-loop control mechanism enables the system to respond quickly to changes in the battery pack's status, ensuring the safety and reliability of the vehicle's power supply.

[0133] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method for a dual-battery pack electrical system, applied to a dual-battery pack electrical system including a first battery pack, a second battery pack, a high-voltage output port, a charging interface, a switching device, multiple unidirectional conducting elements, a voltage regulating device, and a controller, wherein the switching device includes multiple switching elements for establishing different current paths, and the multiple switching elements include, according to their connection positions and control functions, a positive electrode switching element, a negative electrode switching element, a first switching element, a ninth switching element, a tenth switching element, an energy recovery switching element, and an eighth switching element; the multiple unidirectional conducting elements are arranged in corresponding current paths to achieve unidirectional conduction; and the voltage regulating device is used to regulate the voltage, characterized in that... The control method for the dual-battery pack electrical system includes the following steps: S1. Obtain the status information of the first battery pack and the second battery pack through the controller. The status information includes the state of charge, voltage, current and temperature. S2. Based on the status information and the vehicle's power demand, determine the control strategy. The control strategy includes working mode selection, fault protection judgment, and energy balance judgment. The working modes include series charging mode, individual discharge mode, switching mode, and energy recovery mode. S3. Generate control commands for each switching element and the voltage regulation device according to the control strategy; S4. The controller executes the control command to control each switching element to close or open according to a preset timing sequence, thereby establishing a corresponding current path. When executing the switching mode, the eighth switching element is controlled to connect the input terminal of the voltage regulator to the target battery pack. After adjusting the output voltage of the voltage regulator to match the current voltage of the high voltage output port, the corresponding switching element of the target battery pack is closed and the current power supply battery pack is disconnected, thus completing the seamless switching under load. S5. During the execution of the control strategy, continuously monitor the operating status of the first battery pack and the second battery pack. When a change in status is detected, return to step S2 to redetermine the control strategy.

2. The control method for a dual-battery pack electrical system according to claim 1, characterized in that, Before the target battery pack is connected to the high-voltage output port, the bus capacitor of the high-voltage output port is pre-charged, specifically as follows: The eighth switching element is controlled to connect the input terminal of the voltage regulating device to the target battery pack. The voltage regulating device obtains electrical energy from the target battery pack and gradually increases its output voltage until the output voltage reaches the terminal voltage of the target battery pack, thus completing the pre-charging of the bus capacitor. After pre-charging is completed, the voltage regulator switches to normal discharge mode and then executes the switching mode.

3. The control method for a dual-battery pack electrical system according to claim 1, characterized in that, The switching mode employs a smooth switching method based on a voltage regulation device, which includes the following steps: S21. When the current power supply battery pack is switched to the target battery pack, the positive switch element, energy recovery switch element and negative switch element corresponding to the current power supply battery pack are kept closed, and the current power supply battery pack continues to supply power to the high voltage output port. S22. Disconnect the energy recovery switch element corresponding to the current power supply battery pack, control the eighth switch element to connect the input terminal of the voltage regulator to the target battery pack, start the voltage regulator, and obtain input electrical energy from the target battery pack by the voltage regulator; S23. Control the voltage regulating device to gradually increase its output voltage; When the output voltage of the voltage regulator exceeds the terminal voltage of the current power supply battery pack, the voltage regulator takes over the load current of the high voltage output port; S24. After a preset stabilization time, control the positive and negative switch elements corresponding to the target battery pack to close, so that the target battery pack supplies power to the high voltage output port. S25. Disconnect the input-side switching connection of the voltage regulator, disconnect the positive and negative switching elements corresponding to the current power supply battery pack, and close the energy recovery switching element corresponding to the target battery pack to complete the battery pack switching. During the switching process, the voltage fluctuation amplitude at the high-voltage output port is less than the preset voltage fluctuation threshold.

4. The control method for a dual-battery pack electrical system according to claim 3, characterized in that, The voltage regulating device is controlled by the following steps: S31. According to the target operating mode, the input terminal of the voltage regulation device is selected by the eighth switching element, the input terminal including the positive terminal of the second battery pack; S32. Detect the input voltage and output voltage of the voltage regulation device, and calculate the current conversion ratio; S33. According to the voltage demand of the high voltage output port, dynamically adjust the conversion ratio of the voltage regulation device to keep the output voltage within the target voltage range; S34. During the battery pack switching process, the output power of the voltage regulation device is adjusted to achieve a smooth power transition between the old and new power supply battery packs.

5. The control method for a dual-battery pack electrical system according to claim 1, characterized in that, During the execution of the series charging mode, when the vehicle's power demand is detected, the eighth switching element is controlled to connect the input terminal of the voltage regulator to the positive terminal of the second battery pack. The voltage regulator then draws power from the positive terminal of the second battery pack to supply power to the high-voltage output port, thus enabling simultaneous series charging and vehicle power consumption.

6. The control method for a dual-battery pack electrical system according to claim 1, characterized in that, The series charging mode is performed by the following steps: S41. After detecting that the charging interface is connected to an external charging pile, determine the state of charge of the first battery pack and the second battery pack. S42. When the state of charge of the first battery pack and the second battery pack both support high-power charging, determine that the series charging mode is adopted, generate a series charging control command, and control the first switch element, the ninth switch element and the tenth switch element to close, while other switch elements are opened. S43. Establish a series charging circuit. The charging current flows from the positive terminal of the charging interface into the positive terminal of the first battery pack through the ninth switching element, flows out from the negative terminal of the first battery pack after passing through the first battery pack, flows into the positive terminal of the second battery pack through the first switching element and the unidirectional conducting element of the series path, flows out from the negative terminal of the second battery pack after passing through the second battery pack, and flows back to the negative terminal of the charging interface through the tenth switching element. S44. During the charging process, monitor the voltage and temperature of each battery pack in real time. When the voltage of any battery pack reaches the charging cutoff voltage or the temperature exceeds the preset safe temperature range, disconnect the first switching element and switch to the individual charging mode to continue charging only the battery packs that are not fully charged.

7. The control method for a dual-battery pack electrical system according to claim 1, characterized in that, The individual discharge mode is performed by the following steps: S51. Calculate the availability score of each battery pack based on the state of charge, temperature and health status of the first and second battery packs. The availability score comprehensively considers the temperature adaptability, state of charge and health status of each battery pack under the current ambient temperature. S52. Select the battery pack with the higher score as the power supply battery pack; If the first battery pack scores high, then the corresponding positive electrode switch element, energy recovery switch element, and negative electrode switch element of the first battery pack are closed, and other discharge-related switch elements are opened. If the second battery pack scores higher, then the corresponding positive electrode switch, energy recovery switch, and negative electrode switch of the second battery pack will be closed, and other discharge-related switch elements will be opened. S53. Establish a corresponding discharge circuit. The current flows from the positive terminal of the power supply battery pack through the positive terminal switching element and the energy recovery switching element to the positive terminal output of the high voltage output port. After supplying power to the vehicle load, the current flows back from the negative terminal output of the high voltage output port through the negative terminal switching element to the negative terminal of the power supply battery pack. S54. During the discharge process, monitor the state of charge and temperature of the power supply battery pack in real time. When the state of charge is lower than the preset switching threshold or the temperature exceeds the preset safe temperature range, trigger the switching mode.

8. The control method for a dual-battery pack electrical system according to claim 1, characterized in that, The energy recovery mode is executed through the following steps: S61. When a vehicle braking signal is detected, determine the current power supply battery pack; S62. If the current power supply is the first battery pack, an energy recovery control command for the first battery pack is generated to control the positive terminal switch element, energy recovery switch element and negative terminal switch element corresponding to the first battery pack to remain closed, establish an energy recovery circuit, and the braking energy flows from the positive terminal of the high voltage output port through the energy recovery switch element and the positive terminal switch element to the positive terminal of the first battery pack to charge the first battery pack. If the current power supply is the second battery pack, an energy recovery control command for the second battery pack is generated to control the corresponding positive terminal switch element, energy recovery switch element and negative terminal switch element of the second battery pack to remain closed, establish an energy recovery circuit, and the braking energy flows from the positive terminal of the high voltage output port through the energy recovery switch element and the positive terminal switch element to the positive terminal of the second battery pack to charge the second battery pack. S63. During the energy recovery process, monitor the recovery current and battery pack voltage in real time. When the battery pack voltage reaches the charging cutoff voltage or the recovery current drops below the preset current threshold, disconnect the corresponding energy recovery switching element and exit the energy recovery mode.

9. The control method for a dual-battery pack electrical system according to claim 1, characterized in that, The switching mode is triggered when the state of charge of the current power supply battery pack is lower than the preset switching threshold, the temperature of the current power supply battery pack exceeds the preset safe temperature range, the current power supply battery pack detects a fault or a significant performance degradation, or a manual switching command is received from the driver. When any of the above conditions are met, the switching process is initiated to switch from the current power supply battery pack to another battery pack.

10. The control method for a dual-battery pack electrical system according to claim 1, characterized in that, Fault protection control is performed through the following steps: S81. Monitor the voltage, current and temperature of the first and second battery packs in real time to determine whether each parameter is within the normal range; S82. Fault protection is triggered when one of the following anomalies is detected: The battery pack voltage is lower than the preset lower limit voltage or higher than the preset upper limit voltage; The battery pack charging and discharging current exceeds the preset current safety threshold. The battery pack temperature is below the preset lower limit or above the preset upper limit. A short circuit or open circuit fault occurs in a unidirectional conducting element or a switching element; S83. Generate and execute corresponding protection control commands based on the fault type and the faulty battery pack: If the faulty battery pack is the currently powered battery pack, immediately initiate the switching process to switch to another battery pack for power supply. If the other battery pack is also faulty, disconnect all discharge switching components and stop power supply. If the faulty battery pack is a non-power supply battery pack, immediately isolate the battery pack and disconnect all switching components associated with the battery pack to prevent the fault from spreading. S84. Send a fault alarm signal to the vehicle controller and record the fault type, fault occurrence time, fault battery pack identifier and battery pack status information at that time. S85. Do not use the faulty battery pack before the fault is eliminated. Continuously monitor the fault status until the fault is resolved.

11. The control method for a dual-battery pack electrical system according to claim 1, characterized in that, Intercharge control is performed using the following steps: S91. When the vehicle is stationary or in a low-power electrical state, periodically check the state of charge of the first and second battery packs. S92. Calculate the state of charge difference between the two battery packs. When the state of charge of the second battery pack is higher than that of the first battery pack and the difference is greater than the preset equalization threshold, start the inter-battery pack charging process. S93. Control the eighth switch element to close to connect the input terminal of the voltage regulator to the second battery pack, control the energy recovery switch element and negative switch element corresponding to the first battery pack to close, the voltage regulator converts the electrical energy of the second battery pack and flows to the positive terminal of the first battery pack through the energy recovery switch element and the unidirectional conduction element, and then forms a circuit from the negative terminal of the first battery pack through the negative switch element to realize the charging of the first battery pack by the second battery pack. S94. During the mutual charging process between battery packs, monitor the difference in state of charge and charging current between the two battery packs in real time. When the difference in state of charge is less than the preset equalization threshold or the charging current drops below the preset current threshold, disconnect the corresponding switching element and end the mutual charging between battery packs.

12. A dual-battery pack electrical system, characterized in that, include: The first positive terminal and the first negative terminal are used to connect the first battery pack; The second positive terminal and the second negative terminal are used to connect to the second battery pack; The high-voltage output port, including a positive output terminal and a negative output terminal, is used to supply power to the vehicle load; The charging interface includes a positive charging terminal and a negative charging terminal, used to connect to an external charging station; The switching device includes multiple switching elements for establishing different current paths between the first positive terminal, the first negative terminal, the second positive terminal, the second negative terminal, the high-voltage output port, and the charging interface; Multiple unidirectional conducting elements are placed in the corresponding current paths to achieve unidirectional conduction and reverse protection; A voltage regulation device includes an input terminal and an output terminal. The input terminal can be selectively connected to a first positive terminal and a second positive terminal via an eighth switching element. The output terminal is connected to a high-voltage output port for regulating voltage and assisting in battery pack switching. The controller includes a vehicle controller, a first battery management system, and a second battery management system. The controller is electrically connected to each switching element in the switching device and the voltage regulation device, and is used to execute the dual-battery pack electrical system control method as described in any one of claims 1-11.

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