Automotive auxiliary battery charging system, method and vehicle

Abstract

Embodiments of the present application provide a kind of automobile auxiliary battery charging system, method and car, it is related to new energy vehicle technical field.The automobile auxiliary battery charging system includes auxiliary battery module, high voltage distribution module, direct current charging line and direct current charger.The one end of direct current charging line is charging socket, the other end includes terminal, high voltage connector and low voltage connector, auxiliary battery module includes direct current charging signal connector.High voltage distribution module is electrically connected with auxiliary battery module and high voltage connector respectively.Low voltage connector is electrically connected with direct current charging signal connector.Direct current charger is electrically connected with direct current charging line by charging socket.Terminal is grounded.The present application can be very convenient to complete the charging of vehicle auxiliary battery at low cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy vehicles, in particular to an auxiliary battery charging system and method for a vehicle. BACKGROUND

[0002] The power battery of a new energy vehicle is usually divided into a main power battery and an auxiliary battery. The main power battery is responsible for providing the main energy required for vehicle travel, while the auxiliary battery is mainly used for vehicle starting, acceleration energy supply, and energy recovery scenarios.

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

[0004] The prior art generally charges the auxiliary battery by increasing the charging system or disassembling the power battery. Such a solution either increases the manufacturing cost of the vehicle or is time-consuming and labor-intensive. SUMMARY

[0005] The present application aims to, for example, provide an auxiliary battery charging system and method for a vehicle, which can at least partially solve the above technical problems.

[0006] Embodiments of the present application can be implemented as follows:

[0007] In a first aspect, an auxiliary battery charging system for a vehicle is provided, which includes an auxiliary battery module, a high-voltage power distribution module, a DC charging cable, and a DC charging machine. 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.

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

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

[0010] The DC charging machine is electrically connected to the DC charging cable through the charging socket.

[0011] The wiring 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] The high-voltage interface is electrically connected to the original high-voltage wire harness when the auxiliary battery module is not charging, and the original electrical connection is restored.

[0015] Optionally, the auxiliary battery module further comprises 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 comprises a first relay, a second relay and a third relay; the first relay and the second relay are electrically connected to the positive poles of the auxiliary battery module and the high-voltage power distribution module, respectively; the third relay is electrically connected to the negative poles of the auxiliary battery module and the high-voltage power distribution module, respectively; the coil control loop of the first relay, the second relay and the third relay is electrically connected to the battery management module.

[0018] The battery management module is used to close the second relay and the third relay when the battery management module successfully hands with the DC charger when the automobile auxiliary battery charging system is charging, and close the first relay and open the second relay when the voltage before and after the contact points of the second relay and the third relay reaches a preset voltage, so as to complete the connection of the DC charging high-voltage loop.

[0019] Optionally, the DC charging signal connector is matched with a cap plug.

[0020] The cap plug is matched with the DC charging signal connector, and is used to be installed on the DC charging signal connector when the automobile auxiliary battery charging system is not charging, so as to ensure the sealing of the electrical loop.

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

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

[0023] In a second aspect, an automobile auxiliary battery charging method is provided, which is applied to an automobile auxiliary battery charging system, and the automobile auxiliary battery charging system comprises an auxiliary battery module, a high-voltage power distribution module, a DC charging wire and a DC charger; one end of the DC charging wire is a charging socket, and the other end comprises a terminal, a high-voltage connector and a low-voltage connector; the auxiliary battery module comprises a DC charging signal connector, a first relay, a second relay, a third relay and a battery management module; the method comprises:

[0024] When the automobile auxiliary battery charging system enters a charging state, the DC charger performs handshake 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 a maximum output capability message fed back by the DC charger, and sends a pre-charging preparation message to the DC charger to perform pre-charging;

[0026] 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 contact points of the second relay and the third relay reaches a preset voltage, the battery management module closes the first relay, opens 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 opens the high-voltage loop after the charging is completed.

[0028] Optionally, the step of performing handshake between the DC charger and 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 according to a first preset period;

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

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

[0033] In a third aspect, an embodiment of the present application provides an automobile, which includes the automobile auxiliary battery charging system according to any one of the above.

[0034] The beneficial effects of the embodiment of the present application include, for example:

[0035] The present application sets a DC charging line including a high-voltage connector and a low-voltage connector on the automobile, and sets a DC charging signal connector on the auxiliary battery module, so that when the auxiliary battery module is insufficient in power, the DC charger can directly charge the auxiliary battery module through the DC charging line, without the need of additionally increasing a charging system or disassembling the power battery to charge the auxiliary battery module, which is low in cost and simple and effective. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0037] Figure 1 An architectural diagram of an automobile auxiliary battery charging system provided by the embodiments of the present application;

[0038] Figure 2 A connection schematic diagram of a high-voltage interface and a cap plug provided by the embodiments of the present application;

[0039] Figure 3 An electrical schematic diagram of an automobile auxiliary battery charging system provided by the embodiments of the present application;

[0040] Figure 4 A step flowchart of an automobile auxiliary battery charging method provided by the embodiments of the present application.

[0041] Figure: 01-automobile auxiliary battery charging system; 10-auxiliary battery module; 11-direct current 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-direct current charging line; 31-charging socket; 32-wiring terminal; 33-high-voltage connector; 34-low-voltage connector; 40-direct current charger. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0043] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0044] It should be noted that like reference numerals and characters refer to like items throughout the drawings and like item material, once defined in one drawing, is not necessarily further defined and explained in subsequent drawings.

[0045] In addition, if the terms "first", "second" and the like are used herein, they are used only for distinguishing one item from another, and do not imply or suggest a relative importance.

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

[0047] With the vigorous development of new energy automobile industry, as the core component of the power battery, the optimization of its performance and charging technology has become the focus of the industry. The role of the power battery system of new energy vehicles is usually divided into two types: main power battery and small capacity auxiliary power battery. 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 and acceleration energy supply, as well as energy recovery and other scenes. However, in actual application, small capacity auxiliary power battery often faces the problem of rapid power loss, especially when the vehicle is parked for a long time, high-power devices are started, or the energy supplement system cannot charge it.

[0048] When the auxiliary power battery is out of power, if other energy systems of the vehicle cannot provide charging support, it will cause the vehicle to be unable to start or the related auxiliary equipment to work abnormally. In view of this problem, the mainstream solution in the industry at present mainly includes increasing the charging system or directly disassembling the power battery for charging.

[0049] However, both of these two solutions have significant defects: the former includes two types of increasing alternating current charging system or direct current charging system. The alternating current charging system usually needs to add on-board charger, alternating current charging line, software control module and charging interface fixing parts on the vehicle body or accessories. While the direct current charging system involves increasing direct current charging line and corresponding charging interface fixing parts on the vehicle body or accessories. Obviously, this increases the manufacturing cost of the vehicle. The latter needs to send the power battery to a professional maintenance center for charging. This method is technically feasible and can solve the charging problem of the auxiliary power battery. But 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 maintenance point for charging treatment, which is time-consuming and laborious, and may adversely affect the use reliability and service life of the vehicle installation point.

[0050] Based on the above situation, the embodiment of the present application provides an automobile auxiliary battery charging system and method, and an automobile, which can effectively alleviate the above technical problems.

[0051] Please refer to Figure 1This invention provides an automotive auxiliary battery charging system 01, which 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 block 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 via the charging socket 31. The terminal block 32 is grounded.

[0054] The DC charger 40 can be a portable charger to improve 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 in the trunk of the vehicle. 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 through a nut or bolt connection or other means, 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 wiring connections 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 charging, the high-voltage interface 21 is electrically connected to the original high-voltage harness, restoring the original electrical connection.

[0059] like Figure 2 As shown, the high-voltage interface 21 can be an interface connecting the air conditioner PTC or other high-voltage components to the high-voltage power distribution module 20. When the auxiliary battery module 10 does not need charging, the high-voltage interface 21 is normally connected to the air conditioner PTC or other high-voltage components. When the auxiliary battery module 10 needs charging, the user can disconnect the air conditioner 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 comprises a battery management module 12. The battery management module 12 is electrically connected with the low-voltage connector 34 through the DC charging signal connector 11.

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

[0062] Optionally, the auxiliary battery module 10 further comprises 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 with the positive electrode of the auxiliary battery module 10 and the high-voltage power distribution module 20, and the third relay 15 is respectively electrically connected with the negative electrode of the auxiliary battery module 10 and the high-voltage power distribution module 20; the coil control loop of the first relay 13, the second relay 14 and the third relay 15 is electrically connected with the battery management module 12.

[0063] The battery management module 12 is used to close the second relay 14 and the third relay 15 after the battery management module 12 successfully handshakes with the DC charger 40 when the automobile auxiliary battery charging system 01 is charging, and close the first relay 13 and open the second relay 14 after the voltage before and after the contact of the second relay 14 and the third relay 15 reaches a preset voltage, so as to complete the connection of the DC charging high-voltage loop. Please refer to Figure 3 , the first relay 13, the second relay 14 and the third relay 15 are arranged in the auxiliary battery module 10, the first relay 13 and the second relay 14 are respectively electrically connected with the positive electrode of the auxiliary battery management module 12 and the high-voltage power distribution module 20, and the third relay 15 is respectively electrically connected with the negative electrode of the auxiliary battery management module 12 and the high-voltage power distribution module 20.

[0064] When the auxiliary battery module 10 is charging, the battery management module 12 first handshakes with the DC charger 40, and 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 contact 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 loop.

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

[0066] As shown in Figure 2 , 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 connection state, which not only ensures the sealing performance, but also does not need to additionally increase the DC high-voltage circuit interface, thereby reducing the cost.

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

[0068] The electrical interface of the DC charging high-voltage circuit access is a high-voltage low-current interface, the cross-sectional area of the wire is controlled between 2.0mm 2 and 4.0mm 2 , and the corresponding current passing capacity is 15A-25A. Therefore, the high-voltage circuit wire harness of the DC charging wire 30 also adopts a matched connector, and no additional changes are needed on other equipment.

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

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

[0071] Based on the same inventive concept, the embodiment of the present application provides an automobile auxiliary battery charging method, which is applied to an automobile auxiliary battery charging system 01, and the automobile auxiliary battery charging system 01 includes an auxiliary battery module 10, a high-voltage power distribution module 20, a DC charging wire 30, and a DC charger 40. One end of the DC charging wire 30 is a charging socket 31, and the other end includes a wiring 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 shown in Figure 4 .

[0072] Step S110: When the auxiliary battery charging system 01 enters the charging state, the DC charger 40 performs handshake with the battery management module 12 through 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 a maximum output capability 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: In 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 a preset voltage, the battery management module 12 closes the first relay 13, opens 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 loop after the charging is completed.

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

[0077] When starting charging, the DC charger 40 performs handshake with the battery management module 12 through a message, after the handshake is completed, the battery management module 12 sends a charging parameter message to the DC charger 40, receives a maximum output capability 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] In 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 a preset voltage, the battery management module 12 closes the first relay 13, opens 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 charging the auxiliary battery module 10, and disconnects the high-voltage loop after the charging is completed.

[0080] Optionally, the step of the DC charger 40 performing handshake with the battery management module 12 through 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 a first preset period.

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

[0084] The battery management module 12 receives the identification message, sends an identification success message to the DC charger 40 according to a third preset period, and completes the handshake with the DC charger 40.

[0085] After the DC charging line 30 and the DC charger 40 are reliably connected, the DC charger 40 detects the reliable connection, locks the electronic lock, locks the charging socket 31 and the plug, avoids sudden disconnection, and then sends a handshake message through the Figure 3 A+, A- shown in the figure provide a low-voltage auxiliary power supply, and then send a handshake message.

[0086] After the vehicle controller receives the +12V voltage signal provided by the A+ power supply line, the vehicle enters the DC charging mode, and the vehicle is prohibited from driving. After the battery management module 12 is woken up by the A+ hard line, the battery management module 12 enters the DC charging mode and detects the CC2 loop to determine 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 of the charger, receives the handshake message of the DC charger 40, and periodically sends a handshake success message.

[0087] After the DC charger 40 receives the handshake success message, the internal insulation detection is started, and after the insulation resistance is normal, the identification message is periodically sent.

[0088] After the battery management module 12 receives the identification message sent by the DC charger 40, the identification success message is periodically sent, indicating that the battery management module 12 and the DC charger 40 complete the handshake.

[0089] Based on the same inventive concept, the specification embodiments of the present application provide an automobile, which includes the automobile auxiliary battery charging system 01 of any one of the above.

[0090] The present application at least includes the following beneficial effects:

[0091] The present application sets the DC charging line including the high-voltage connector and the low-voltage connector on the automobile, and sets the DC charging signal connector on the auxiliary battery module, so that when the auxiliary battery module is insufficient, the DC charger can directly charge the auxiliary battery module through the DC charging line, without the need to additionally increase the charging system or disassemble the power battery to charge the auxiliary battery module, which is low in cost and simple and effective.

[0092] In several embodiments provided by the present application, it should be understood that the disclosed apparatus and method can also be implemented in other manners. The described embodiments of the apparatus are merely exemplary, and the possible implementation manners of the apparatus, method and computer program product according to the present application are shown in the flowcharts and block diagrams in the accompanying drawings. In this regard, each block in the flowcharts or block diagrams can represent a module, a segment or a portion of code which comprises one or more executable instructions for implementing the specified logic function. It should also be noted that in some alternative implementations, the functions shown in the blocks can occur in different orders from those shown in the accompanying drawings. For example, two blocks shown in succession can actually be executed substantially concurrently or in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented by dedicated hardware-based systems which perform the specified functions or actions, or can be implemented by a combination of dedicated hardware-based systems and computer instructions.

[0093] In addition, the various functional modules in the various embodiments of the present application can be integrated together to form a separate part, or each module can exist independently, or two or more modules can be integrated to form a separate part.

[0094] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product. The 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 the various embodiments of the present application. The aforementioned storage medium includes various media that can store program codes, such as a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0095] The above is merely specific embodiments of the present application, and the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed by the present application can be easily conceived by those skilled in the art, and should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An automotive auxiliary battery charging system, characterized by, 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 direct-current charging wire is a charging socket, and the other end comprises a wiring terminal, a high-voltage connector and a low-voltage connector; the auxiliary battery module comprises a direct-current charging signal connector; The high-voltage power distribution module is electrically connected with the auxiliary battery module and the high-voltage connector respectively; The low-voltage connector is electrically connected with the direct-current charging signal connector; The direct-current charger is electrically connected with the direct-current charging wire through the charging socket; The wiring terminal is grounded.

2. The automotive auxiliary battery charging system of claim 1, wherein, The high-voltage power distribution module comprises a high-voltage interface; The high-voltage connector is electrically connected with the high-voltage power distribution module through the high-voltage interface; When the auxiliary battery module is not charging, the high-voltage interface is electrically connected to the original high-voltage wire harness to restore the original electrical connection.

3. The automotive auxiliary battery charging system of claim 1, wherein, The auxiliary battery module further comprises a battery management module; The battery management module is electrically connected with the low-voltage connector through the direct-current charging signal connector.

4. The auxiliary battery charging system for an automobile as set forth in claim 3, wherein The auxiliary battery module further comprises a first relay, a second relay and a third relay; the first relay and the second relay are electrically connected with the positive poles of the auxiliary battery module and the high-voltage power distribution module respectively, and the third relay is electrically connected with the negative poles of the auxiliary battery module and the high-voltage power distribution module respectively; the coil control loop of the first relay, the second relay and the third relay is electrically connected with the battery management module; The battery management module is used to close the second relay and the third relay when the battery management module successfully hands with the direct-current charger when the automobile auxiliary battery charging system is charging, and close the first relay and open the second relay when the voltage before and after the contact points of the second relay and the third relay reaches a preset voltage, so as to complete the connection of the direct-current charging high-voltage loop.

5. The auxiliary battery charging system for an automobile as set forth in claim 1, wherein, The direct-current charging signal connector is matched with a cap plug; The cap plug is adapted with the direct-current charging signal connector and is used to be installed on the direct-current charging signal connector when the automobile auxiliary battery charging system is not charging, so as to ensure the sealing property of the electrical loop.

6. The auxiliary battery charging system for an automobile as set forth in claim 1, wherein, The cross-sectional area of the direct current charging wire is between 2mm 2 and 4mm 2 and the current passing through the direct current charging wire is between 15A and 25A.

7. The auxiliary battery charging system for an automobile as claimed in claim 1, wherein, The power of the direct-current charger is 3.5KW or 7KW.

8. An automobile auxiliary battery charging method characterized by comprising: The application is applied to an automobile auxiliary battery charging system, which comprises an auxiliary battery module, a high-voltage distribution module, a direct-current charging wire and a direct-current charger; one end of the direct-current charging wire is a charging socket, and the other end comprises a terminal, a high-voltage connector and a low-voltage connector; the direct-current charger is electrically connected with the direct-current charging wire through the charging socket; the auxiliary battery module comprises a direct-current charging signal connector, a first relay, a second relay, a third relay and a battery management module; the high-voltage distribution module is electrically connected with the auxiliary battery module and the high-voltage connector respectively; the low-voltage connector is electrically connected with the direct-current charging signal connector; the direct-current charger is electrically connected with the direct-current charging wire through the charging socket; the terminal is grounded; the first relay and the second relay are electrically connected with the positive poles of the auxiliary battery module and the high-voltage distribution module respectively; the third relay is electrically connected with the negative poles of the auxiliary battery module and the high-voltage distribution module respectively; the coil control loop of the first relay, the second relay and the third relay is electrically connected with the battery management module; the method comprises: When the automobile auxiliary battery charging system enters a charging state, the direct-current 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 direct-current charger, receives a maximum output capacity message fed back by the direct-current charger, and sends a pre-charging preparation message to the direct-current charger to perform pre-charging; In the pre-charging stage, the battery management module closes the second relay and the third relay, and closes the first relay and opens the second relay when the voltage before and after the contact points of the second relay and the third relay reaches a preset voltage, and sends a charging preparation message to the direct-current charger; The direct-current charger receives the charging preparation message, charges the auxiliary battery module, and opens the high-voltage loop after the charging is completed.

9. The method of claim 8, wherein the auxiliary battery of the vehicle is charged by the power supply of the vehicle. The step of performing handshake between the direct-current charger and the battery management module through a message comprises: The direct-current 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 direct-current charger according to a first preset period; After receiving the handshake success message, the direct-current charger starts insulation detection, and sends an identification message to the battery management module according to a second preset period after the insulation detection is normal; After receiving the identification message, the battery management module sends an identification success message to the direct-current charger according to a third preset period to complete the handshake with the direct-current charger.

10. An automobile characterized by comprising: The automobile comprises the automobile auxiliary battery charging system according to any one of claims 1-7.

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