Automobile auxiliary battery charging system and method and automobile

Abstract

The embodiment of the invention provides an automobile auxiliary battery charging system and method and an automobile, and relates to the technical field of new energy automobiles. The automobile auxiliary battery charging system comprises an auxiliary battery module, a high-voltage power distribution module, a direct-current charging wire and a direct-current charger. One end of the DC charging wire is a charging socket, the other end comprises a wiring terminal, a high-voltage connector and a low-voltage connector, and the auxiliary battery module comprises a DC charging signal connector. The high-voltage power distribution module is electrically connected with the auxiliary battery module and the high-voltage connector. And the low-voltage connector is electrically connected with the direct-current charging signal connector. And the direct-current charger is electrically connected with the direct-current charging wire through the charging socket. And the wiring terminal is grounded. According to the invention, the charging of the auxiliary battery of the vehicle can be completed very simply and conveniently under the condition of low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and more particularly, to an auxiliary battery charging system and method for a vehicle, and a vehicle. Background Art

[0002] The power battery of a new energy vehicle generally serves as the main power battery and the auxiliary battery. The main power battery is responsible for providing the main energy required for vehicle driving, while the auxiliary battery is mainly used in scenarios such as vehicle starting, acceleration energy supply, and energy recovery.

[0003] In practical applications, the auxiliary battery often faces the problem of rapid power depletion due to its small capacity, especially when the vehicle is parked for a long time, high-power devices are started, or the energy replenishment system cannot charge it.

[0004] The prior art generally charges the auxiliary battery by adding a charging system or disassembling the power battery. Such solutions either increase the vehicle manufacturing cost or are time-consuming and laborious. Summary of the Invention

[0005] The objectives of the present invention include, for example, providing an auxiliary battery charging system and method for a vehicle, and a vehicle, which can at least partially solve the above technical problems.

[0006] Embodiments of the present invention may be implemented as follows:

[0007] In a first aspect, an embodiment of the present invention provides an auxiliary battery charging system for a vehicle. The auxiliary battery charging system includes an auxiliary battery module, a high-voltage power distribution module, a DC charging cable, and a DC charger; one end of the DC charging cable is a charging socket, and the other end includes a terminal, a high-voltage connector, and a low-voltage connector. The auxiliary battery module includes a DC charging signal connector;

[0008] The high-voltage power distribution module is electrically connected to the auxiliary battery module and the high-voltage connector respectively;

[0009] The low-voltage connector is electrically connected to the DC charging signal connector;

[0010] The DC charger is electrically connected to the DC charging cable through the charging socket;

[0011] The terminal is grounded.

[0012] Optionally, the high-voltage power distribution module includes a high-voltage interface;

[0013] The high-voltage connector is electrically connected to the high-voltage power distribution module through the high-voltage interface;

[0014] When the auxiliary battery module is not charging, the high-voltage interface is electrically connected to the original high-voltage harness to restore the original electrical connection.

[0015] Optionally, the auxiliary battery module further includes a battery management module;

[0016] The battery management module is electrically connected to the low-voltage connector through the DC charging signal connector.

[0017] Optionally, the auxiliary battery module further includes a first relay, a second relay, and a third relay; the first relay and the second relay are respectively electrically connected to the positive electrodes of the auxiliary battery module and the high-voltage power distribution module, and the third relay is respectively electrically connected to the negative electrodes of the auxiliary battery module and the high-voltage power distribution module; the coil control circuits of the first relay, the second relay, and the third relay are electrically connected to the battery management module;

[0018] When the vehicle auxiliary battery charging system is charging, after the battery management module successfully shakes hands with the DC charger, the battery management module closes the second relay and the third relay, and when the voltage before and after the contacts of the second relay and the third relay reaches a preset voltage, closes the first relay and disconnects the second relay to complete the connection of the DC charging high-voltage circuit.

[0019] Optionally, the DC charging signal connector is equipped with a cap plug;

[0020] The cap plug is adapted to the DC charging signal connector and is used to be installed on the DC charging signal connector when the vehicle auxiliary battery charging system is not charging to ensure the sealing of the electrical circuit.

[0021] Optionally, the cross-sectional area of the DC charging line is between 2.0 mm 2 ~4.0 mm 2 and the current passing through the DC charging line is 15A - 25A.

[0022] Optionally, the power of the DC charger is 3.5KW or 7KW.

[0023] In a second aspect, an embodiment of the present invention provides a method for charging a vehicle auxiliary battery, which is applied to a vehicle auxiliary battery charging system. The vehicle auxiliary battery charging system includes an auxiliary battery module, a high-voltage power distribution module, a DC charging line, and a DC charger; one end of the DC charging line is a charging socket, and the other end includes a wiring terminal, a high-voltage connector, and a low-voltage connector. The auxiliary battery module includes a DC charging signal connector, a first relay, a second relay, a third relay, and a battery management module; the method includes:

[0024] When the vehicle auxiliary battery charging system enters the charging state, the DC charger shakes hands with the battery management module through a message;

[0025] After the handshake is completed, the battery management module sends a charging parameter message to the DC charger, receives the maximum output capacity message fed back by the DC charger, and sends a pre-charging preparation message to the DC charger for pre-charging;

[0026] During the pre-charging stage, the battery management module closes the second relay and the third relay, and after the voltage before and after the contacts of the second relay and the third relay reaches a preset voltage, closes the first relay, disconnects the second relay, and sends a charging preparation message to the DC charger;

[0027] The DC charger receives the charging preparation message, charges the auxiliary battery module, and disconnects the high-voltage circuit after the charging is completed.

[0028] Optionally, the step of the DC charger shaking hands with the battery management module through a message includes:

[0029] The DC charger sends a handshake message to the battery management module;

[0030] The battery management module receives the handshake message and sends a handshake success message to the DC charger at a first preset period;

[0031] After receiving the handshake success message, the DC charger starts insulation detection, and after the insulation detection is normal, sends an identification message to the battery management module at a second preset period;

[0032] After receiving the identification message, the battery management module sends an identification success message to the DC charger at a third preset period to complete the handshake with the DC charger.

[0033] In a third aspect, an embodiment of the present invention provides a vehicle, and the vehicle includes the vehicle auxiliary battery charging system described in any one of the above.

[0034] The beneficial effects of the embodiments of the present invention include, for example:

[0035] By providing a DC charging line including a high-voltage connector and a low-voltage connector on the vehicle and a DC charging signal connector on the auxiliary battery module in the present invention, when the auxiliary battery module has insufficient power, the DC charger can directly charge the auxiliary battery module through the DC charging line, without the need to additionally increase a charging system or disassemble the power battery to charge the auxiliary battery module, which is low-cost, simple and effective. Description of the Drawings

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0037] Figure 1 It is an architecture diagram of an automotive auxiliary battery charging system provided by an embodiment of the present invention;

[0038] Figure 2 It is a schematic connection diagram of a high-voltage interface and a cap plug provided by an embodiment of the present invention;

[0039] Figure 3 It is an electrical schematic diagram of an automotive auxiliary battery charging system provided by an embodiment of the present invention;

[0040] Figure 4 It is a step flowchart of an automotive auxiliary battery charging method provided by an embodiment of the present invention.

[0041] Icons: 01 - Automotive auxiliary battery charging system; 10 - Auxiliary battery module; 11 - DC charging signal connector; 12 - Battery management module; 13 - First relay; 14 - Second relay; 15 - Third relay; 16 - Cap plug; 20 - High-voltage power distribution module; 21 - High-voltage interface; 30 - DC charging cable; 31 - Charging socket; 32 - Terminal block; 33 - High-voltage connector; 34 - Low-voltage connector; 40 - DC charger. Specific embodiments

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0043] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0044] It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0045] In addition, terms such as "first" and "second" are only used for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0046] It should be noted that, without conflict, the features in the embodiments of the present invention can be combined with each other.

[0047] With the booming development of the new energy vehicle industry, as the core component of new energy vehicles, the performance and optimization of charging technology of power batteries have become the focus of the industry. The functions of the power battery system of new energy vehicles are usually divided into two types: main power batteries and small-capacity auxiliary power batteries. The main power battery is responsible for providing the main energy required for vehicle driving, while the auxiliary power battery is mainly used for vehicle starting, accelerating energy supply, and energy recovery scenarios. However, in actual applications, small-capacity auxiliary power batteries often face the problem of rapid power depletion, especially when the vehicle is parked for a long time, high-power devices are started, or the energy replenishment system cannot charge them.

[0048] When the auxiliary power battery runs out of power, if other energy systems of the vehicle cannot provide charging support for it, it will cause the vehicle to be unable to start or related auxiliary devices to malfunction. To address this problem, the current mainstream solutions in the industry mainly include adding a charging system or directly disassembling the power battery for charging.

[0049] However, both of these solutions have significant drawbacks: The former includes two types: adding an AC charging system or a DC charging system. The AC charging system usually requires adding an on-vehicle charger, an AC charging cable, a software control module, and a charging interface fixing component on the vehicle body or accessories. The DC charging system involves adding a DC charging cable and the corresponding charging interface fixing component on the vehicle body or accessories. Obviously, this increases the vehicle manufacturing cost. The latter requires sending the power battery to a professional repair center for charging. This method is technically feasible and can solve the charging problem of the auxiliary power battery. However, implementing this solution requires professional technology and tools to disassemble and install the power battery. At the same time, the vehicle needs to be transported to the repair point for charging, which is time-consuming and laborious, and may have an adverse impact on the use reliability and lifespan of the vehicle installation point.

[0050] Based on the above situation, the embodiments of the present invention provide an automotive auxiliary battery charging system, method, and vehicle, which can effectively alleviate the above technical problems.

[0051] Please refer to Figure 1, this is an automotive auxiliary battery charging system provided by an embodiment of the present invention. The automotive auxiliary battery charging system 01 includes an auxiliary battery module 10, a high-voltage power distribution module 20, a DC charging cable 30, and a DC charger 40. One end of the DC charging cable 30 is a charging socket 31, and the other end includes a terminal 32, a high-voltage connector 33, and a low-voltage connector 34. The auxiliary battery module 10 includes a DC charging signal connector 11.

[0052] The high-voltage power distribution module 20 is electrically connected to the auxiliary battery module 10 and the high-voltage connector 33 respectively.

[0053] The low-voltage connector 34 is electrically connected to the DC charging signal connector 11. The DC charger 40 is electrically connected to the DC charging cable 30 through the charging socket 31. The terminal 32 is grounded.

[0054] The DC charger 40 can be a mobile charger to improve the charging convenience. Similarly, the DC charging cable 30 can be a charging cable independent of the vehicle. When the auxiliary battery module 10 does not need to be charged, the DC charging cable 30 can be stored in a repair shop or the vehicle trunk. When the auxiliary battery module 10 needs to be charged, the user can take out the DC charging cable 30 and connect the auxiliary battery module 10 to the DC charger 40 for charging.

[0055] When charging the auxiliary battery module 10, the user only needs to connect the charging socket 31 of the DC charging cable 30 to the DC charger 40, ground the terminal 32 of the DC charging cable 30 in the form of connection by nuts or bolts or other forms, connect the high-voltage connector 33 to the high-voltage power distribution module 20, and connect the low-voltage connector 34 to the DC charging signal connector 11. After completing the line connection between the modules, the auxiliary battery module 10 can be directly charged through the DC charger 40.

[0056] Optionally, the high-voltage power distribution module 20 includes a high-voltage interface 21.

[0057] The high-voltage connector 33 is electrically connected to the high-voltage power distribution module 20 through the high-voltage interface 21.

[0058] When the auxiliary battery module 10 is not being charged, the high-voltage interface 21 is electrically connected to the original high-voltage harness to restore the original electrical connection.

[0059] As Figure 2 shown, the high-voltage interface 21 can be an interface connecting the air-conditioning PTC or other high-voltage components to the high-voltage power distribution module 20. When the auxiliary battery module 10 does not need to be charged, the high-voltage interface 21 is normally connected to the air-conditioning PTC or other high-voltage components. When the auxiliary battery module 10 needs to be charged, the user can unplug the air-conditioning PTC or other high-voltage components and connect the high-voltage connector 33 of the DC charging cable 30 to the high-voltage interface 21.

[0060] Optionally, the auxiliary battery module 10 further includes a battery management module 12. The battery management module 12 is electrically connected to the low-voltage connector 34 through a DC charging signal connector 11.

[0061] As Figure 3 shown, the battery management module 12 is electrically connected to the low-voltage connector 34 of the DC charging line 30 through a DC charging signal connector 11. The battery management module 12 may be a BMS (Battery Management System). When the DC charger 40 charges the auxiliary battery module 10, the battery management module 12 needs to first verify and handshake with the DC charger 40. Only after the handshake is successful can the DC charger 40 be allowed to charge the auxiliary battery module 10, thereby ensuring the safety of charging the auxiliary battery module 10.

[0062] Optionally, the auxiliary battery module 10 further includes a first relay 13, a second relay 14, and a third relay 15; the first relay 13 and the second relay 14 are respectively electrically connected to the positive electrodes of the auxiliary battery module 10 and the high-voltage power distribution module 20, and the third relay 15 is respectively electrically connected to the negative electrodes of the auxiliary battery module 10 and the high-voltage power distribution module 20; the coil control circuits of the first relay 13, the second relay 14, and the third relay 15 are electrically connected to the battery management module 12;

[0063] The battery management module 12 is configured to, when the automotive auxiliary battery charging system 01 is charging, after the battery management module 12 successfully shakes hands with the DC charger 40, close the second relay 14 and the third relay 15, and after the voltage before and after the contacts of the second relay 14 and the third relay 15 reaches a preset voltage, close the first relay 13 and open the second relay 14 to complete the connection of the DC charging high-voltage circuit. Please refer to Figure 3 , a first relay 13, a second relay 14, and a third relay 15 are provided in the auxiliary battery module 10. The first relay 13 and the second relay 14 are respectively electrically connected to the positive electrodes of the auxiliary battery management module 12 and the high-voltage power distribution module 20, and the third relay 15 is respectively electrically connected to the negative electrodes of the auxiliary battery management module 12 and the high-voltage power distribution module 20.

[0064] When the auxiliary battery module 10 is charged, the battery management module 12 first shakes hands with the DC charger 40. After the handshake is completed, the battery management module 12 closes the second relay 14 and the third relay 15. After the voltage before and after the contacts of the second relay 14 and the third relay 15 reaches a preset voltage value, the battery management module 12 closes the first relay 13 and opens the second relay 14, thereby completing the connection of the DC charging high-voltage circuit.

[0065] Optionally, the DC charging signal connector 11 is provided with a cap plug 16. The cap plug 16 is adapted to the DC charging signal connector 11 and is used to be installed on the DC charging signal connector 11 when the automotive auxiliary battery charging system 01 is not charging, so as to ensure the sealing of the electrical circuit.

[0066] As Figure 2 shown, when the auxiliary battery module 10 is not charging, the cap plug 16 can be installed on the DC charging signal connector 11, so as to achieve the effects of waterproofing and dustproofing. At the same time, the high-voltage circuit remains in a normal connected state, which not only ensures the sealing performance but also does not require additional DC high-voltage circuit interfaces, thus reducing the cost.

[0067] Optionally, the cross-sectional area of the DC charging cable 30 is between 2.0 mm 2 and 4.0 mm 2 , and the current passing through the DC charging cable 30 is 15 A to 25 A.

[0068] The electrical interface accessed by the DC charging high-voltage circuit is a high-voltage low-current interface, and its wire cross-sectional area is controlled between 2.0 mm 2 and 4.0 mm 2 , and the corresponding current-carrying capacity is 15 A to 25 A. Therefore, the high-voltage circuit cable of the DC charging cable 30 also adopts a connector matching it, and no additional changes to other devices are required.

[0069] Optionally, the power of the DC charger 40 is 3.5 KW or 7 KW.

[0070] Since the cross-sectional area of the DC charging cable 30 is between 2.0 mm 2 and 4.0 mm 2 , and the current passing through the DC charging cable 30 is 15 A to 25 A. Therefore, setting a DC charger 40 with a power of 3.5 KW or 7 KW can meet the charging requirements.

[0071] Based on the same inventive concept, the embodiment of the present invention provides an automotive auxiliary battery charging method, which is applied to the automotive auxiliary battery charging system 01. The automotive auxiliary battery charging system 01 includes an auxiliary battery module 10, a high-voltage power distribution module 20, a DC charging cable 30, and a DC charger 40. One end of the DC charging cable 30 is a charging socket 31, and the other end includes a terminal 32, a high-voltage connector 33, and a low-voltage connector 34. The auxiliary battery module 10 includes a DC charging signal connector 11, a first relay 13, a second relay 14, a third relay 15, and a battery management module 12. The method includes the following steps as Figure 4 shown:

[0072] Step S110: When the automotive auxiliary battery charging system 01 enters the charging state, the DC charger 40 shakes hands with the battery management module 12 via a message.

[0073] Step S120: After the handshake is completed, the battery management module 12 sends a charging parameter message to the DC charger 40, receives the maximum output capacity message fed back by the DC charger 40, and sends a pre-charging preparation message to the DC charger 40 to perform pre-charging.

[0074] Step S130: During the pre-charging stage, the battery management module 12 closes the second relay 14 and the third relay 15, and after the voltage before and after the contacts of the second relay 14 and the third relay 15 reaches the preset voltage, closes the first relay 13, disconnects the second relay 14, and sends a charging preparation message to the DC charger 40.

[0075] Step S140: The DC charger 40 receives the charging preparation message, charges the auxiliary battery module 10, and disconnects the high-voltage circuit after charging is completed.

[0076] When the auxiliary battery module 10 needs to be charged, the user first connects the DC charger 40 to the auxiliary battery module 10 through the DC charging cable 30, and then connects the DC charger 40 to the 220V AC mains.

[0077] When starting to charge, the DC charger 40 shakes hands with the battery management module 12 via a message. After the handshake is completed, the battery management module 12 sends a charging parameter message to the DC charger 40, receives the maximum output capacity message fed back by the DC charger 40, and sends a pre-charging preparation message to the DC charger 40 to perform pre-charging.

[0078] During the pre-charging stage, the battery management module 12 closes the second relay 14 and the third relay 15, and after the voltage before and after the contacts of the second relay 14 and the third relay 15 reaches the preset voltage, closes the first relay 13, disconnects the second relay 14, and sends a charging preparation message to the DC charger 40.

[0079] The DC charger 40 receives the charging preparation message, starts to charge the auxiliary battery module 10, and disconnects the high-voltage circuit after charging is completed.

[0080] Optionally, the step of the DC charger 40 shaking hands with the battery management module 12 via a message includes:

[0081] The DC charger 40 sends a handshake message to the battery management module 12.

[0082] The battery management module 12 receives the handshake message and sends a handshake success message to the DC charger 40 according to the first preset period.

[0083] After the DC charger 40 receives the handshake success message, it starts the insulation detection, and after the insulation detection is normal, it sends an identification message to the battery management module 12 according to the second preset period.

[0084] After the battery management module 12 receives the identification message, it sends an identification success message to the DC charger 40 according to the third preset period to complete the handshake with the DC charger 40.

[0085] After the DC charging cable 30 and the DC charger 40 are reliably connected, after the DC charger 40 detects the reliable connection, it locks the electronic lock, locks the charging socket 31 and the plug to avoid sudden disconnection, and then closes the internal relay to Figure 3 provide a low-voltage auxiliary power supply through A+ and A- as shown, and then send a handshake message.

[0086] After the vehicle controller receives the +12V voltage signal provided by the A+ power supply line, it will make the vehicle enter the DC charging mode and prohibit the vehicle from driving. After the battery management module 12 is also woken up by the A+ hard wire, it enters the DC charging mode and detects the CC2 circuit to judge whether the charging socket 31 and the plug are reliably connected. If the connection is reliable, the battery management module 12 waits for the handshake message from the charger. After receiving the handshake message from the DC charger 40, it periodically sends a handshake success message.

[0087] After the DC charger 40 receives the handshake success message, it starts the insulation detection internally. After the insulation resistance values are all normal, it periodically sends an identification message.

[0088] After the battery management module 12 receives the identification message sent by the DC charger 40, it also periodically sends an identification success message, indicating that the battery management module 12 and the DC charger 40 have completed the handshake.

[0089] Based on the same inventive concept, the embodiment of the present invention provides an automobile, which includes the vehicle auxiliary battery charging system 01 of any one of the above.

[0090] The present invention has at least the following beneficial effects:

[0091] The present invention provides a DC charging cable including a high-voltage connector and a low-voltage connector on the vehicle, and a DC charging signal connector is arranged on the auxiliary battery module, so that when the auxiliary battery module has insufficient power, the DC charger can directly charge the auxiliary battery module through the DC charging cable, without the need to additionally increase a charging system or disassemble the power battery to charge the auxiliary battery module, which is low-cost and simple and effective.

[0092] In several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions, and operations of devices, methods, and computer program products according to multiple embodiments of the present invention. In this regard, each block in the flowchart or block diagram can represent a module, a program segment, or a part of code, and a module, a program segment, or a part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than that marked in the accompanying drawings. For example, two consecutive blocks can actually be executed substantially in parallel, and they can sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, as well as the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0093] In addition, in each embodiment of the present invention, the functional modules can be integrated together to form an independent part, or each module can exist alone, or two or more modules can be integrated to form an independent part.

[0094] If the function is implemented in the form of a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in each embodiment of the present invention. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs that can store program codes.

[0095] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An automobile auxiliary battery charging system, characterized in that: The automobile auxiliary battery charging system includes an auxiliary battery module, a high-voltage power distribution module, a DC charging cable and a DC charger; one end of the DC charging cable is a charging socket, and the other end includes a wiring terminal, a high-voltage connector and a low-voltage connector, and the auxiliary battery module includes a DC charging signal connector; The high-voltage power distribution module is electrically connected to the auxiliary battery module and the high-voltage connector respectively; The low voltage connector is electrically connected to the DC charging signal connector; The DC charger is electrically connected to the DC charging line via the charging socket; The connection terminal is grounded.

2. The vehicle auxiliary battery charging system as claimed in claim 1, characterized in that: The high-voltage power distribution module includes a high-voltage interface; The high voltage connector is electrically connected to the high voltage power distribution module via the high voltage interface; When the auxiliary battery module is not charged, the high-voltage interface is electrically connected to the original high-voltage wiring harness to restore the original electrical connection.

3. The vehicle auxiliary battery charging system as claimed in claim 1, characterized in that: The auxiliary battery module also includes a battery management module; The battery management module is electrically connected to the low voltage connector through the DC charging signal connector.

4. The vehicle auxiliary battery charging system as claimed in claim 3, characterized in that: The auxiliary battery module further includes a first relay, a second relay and a third relay; the first relay and the second relay are electrically connected to the positive pole of the auxiliary battery module and the high-voltage power distribution module respectively, and the third relay is electrically connected to the negative pole of the auxiliary battery module and the high-voltage power distribution module respectively; the coil control circuits of the first relay, the second relay and the third relay are electrically connected to the battery management module; The battery management module is used to close the second relay and the third relay when the vehicle auxiliary battery charging system is charging, after the battery management module shakes hands with the DC charger successfully, and after the voltage before and after the contacts of the second relay and the third relay reaches a preset voltage, close the first relay and disconnect the second relay to complete the connection of the DC charging high-voltage circuit.

5. The vehicle auxiliary battery charging system as claimed in claim 1, characterized in that: The DC charging signal connector is equipped with a cap plug; The cap plug is adapted to the DC charging signal connector and is used to be installed on the DC charging signal connector when the vehicle auxiliary battery charging system is not charging, so as to ensure the sealing of the electrical circuit.

6. The vehicle auxiliary battery charging system as claimed in claim 1, characterized in that: The cross-sectional area of ​​the DC charging line is 2.0 mm 2 ~4.0mm 2 The current passing through the DC charging line is between 15A and 25A.

7. The vehicle auxiliary battery charging system as claimed in claim 1, characterized in that: The power of the DC charger is 3.5KW or 7KW.

8. A method for charging an auxiliary battery of an automobile, characterized in that: Applied to an automobile auxiliary battery charging system, the automobile auxiliary battery charging system includes an auxiliary battery module, a high-voltage power distribution module, a DC charging cable and a DC charger; one end of the DC charging cable is a charging socket, and the other end includes a wiring terminal, a high-voltage connector and a low-voltage connector; the auxiliary battery module includes a DC charging signal connector, a first relay, a second relay, a third relay and a battery management module; the method includes: When the vehicle auxiliary battery charging system enters the charging state, the DC charger performs handshake with the battery management module through a message; After the handshake is completed, the battery management module sends a charging parameter message to the DC charger, receives a maximum output capacity message fed back by the DC charger, and sends a pre-charging preparation message to the DC charger for pre-charging; In the pre-charging stage, the battery management module closes the second relay and the third relay, and after the voltage before and after the contacts of the second relay and the third relay reaches a preset voltage, closes the first relay, disconnects the second relay, and sends a charging preparation message to the DC charger; The DC charger receives the charging preparation message, charges the auxiliary battery module, and disconnects the high-voltage circuit after charging is completed.

9. The method for charging an auxiliary battery of an automobile as claimed in claim 8, characterized in that: The step of the DC charger performing handshake with the battery management module through a message includes: The DC charger sends a handshake message to the battery management module; The battery management module receives the handshake message, and sends a handshake success message to the DC charger according to a first preset period; After receiving the handshake success message, the DC charger starts insulation detection, and after the insulation detection is normal, sends an identification message to the battery management module according to a second preset period; After receiving the identification message, the battery management module sends an identification success message to the DC charger according to a third preset period to complete the handshake with the DC charger.

10. An automobile, characterized in that: The automobile comprises the automobile auxiliary battery charging system according to any one of claims 1 to 7.

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