Direct current charging expander of electric automobile and control method

Abstract

The invention discloses a direct current charging expander of an electric vehicle and a control method, and the direct current charging expander comprises a charging gun head which is used for being connected with a charging gun seat of the electric vehicle; the first charging gun seat is used for being connected with an external charging gun of the first charging pile; the second charging gun seat is used for being connected with an external charging gun of a second charging pile; the expansion controller is electrically connected with the charging gun head, the first charging gun base and the second charging gun base and used for controlling the first charging pile and the second charging pile to charge the electric vehicle through the charging gun head. According to the technical scheme, the direct-current charging expander is utilized, multiple charging guns can be used for charging the electric vehicle at the same time, the effect of an over-charging pile is achieved through a common fast charging pile, and the charging speed is increased.

Description

Technical Field

[0001] The present application relates to the field of new energy electric vehicle charging control, and in particular to a DC charging extender and control method for an electric vehicle. Background Art

[0002] There are a large number of charging piles with low charging power. As the configuration of electric vehicles continues to improve, the charging speed of these charging piles can no longer meet the needs of some customers. Although super charging piles have fast charging speeds, they require large investments and are not economically viable.

[0003] If two or more charging guns can be used to charge an electric car with only one DC charging gun socket at the same time, the supercharging effect can be achieved with a lower-power charging pile, improving the economy and convenience of charging.

[0004] Some of the existing electric vehicles have only one DC charging gun socket, while others have two. In the prior art, each charging gun socket can only be plugged with one charging gun, and it is impossible to charge the electric vehicle with two charging guns through one gun socket at the same time. Summary of the invention

[0005] The purpose of this application is to provide a DC charging extender and control method for electric vehicles. Using the DC charging extender, multiple charging guns can be used to charge the electric vehicle at the same time, and the effect of a super charging pile can be achieved with an ordinary fast charging pile, thereby increasing the charging speed.

[0006] To achieve the above objectives, this application provides the following solutions:

[0007] In a first aspect, the present application provides a DC charging extender for an electric vehicle, comprising:

[0008] A charging gun head, used to connect to the charging gun holder of an electric vehicle;

[0009] At least two charging gun holders, used to connect to the charging guns of the charging pile;

[0010] The extended controller is electrically connected to the charging gun head and the at least two charging gun seats respectively, and is used to control the at least two charging gun seats to receive the electric energy input by the charging pile, and charge the electric vehicle through the charging gun head.

[0011] Optionally, the DC contacts of the at least two charging gun sockets are respectively connected to the DC contacts of the charging gun head, so as to perform DC charging on the electric vehicle through the DC contacts of the charging gun head.

[0012] Optionally, the grounding contacts of the at least two charging gun sockets are respectively connected to the grounding contacts of the charging gun head, so as to be connected to the vehicle ground through the grounding contacts of the charging gun head.

[0013] Optionally, the charging confirmation contact of the main charging gun seat among the at least two charging gun seats is connected to the charging confirmation contact of the charging gun head to confirm that the charging gun of the charging pile has been connected to the main charging gun seat and the charging gun has been connected to the charging gun seat of the electric vehicle.

[0014] Optionally, a first charging confirmation contact of a secondary charging gun seat among the at least two charging gun seats is connected to a ground contact of the charging gun head through a resistor, and a second charging confirmation interface of the secondary charging gun seat is vacant.

[0015] Optionally, the low-voltage auxiliary contact of the main charging gun seat of the at least two charging gun seats is respectively connected to the low-voltage auxiliary contact of the charging gun of the charging pile and a low-voltage auxiliary contact of the extended controller;

[0016] The low-voltage auxiliary contacts of the secondary charging gun seats of the at least two charging gun seats are respectively connected to the low-voltage auxiliary contacts of the charging gun of the charging pile and a low-voltage auxiliary contact of the extended controller;

[0017] A low-voltage auxiliary contact of the extended controller is connected to the low-voltage auxiliary contact of the charging gun head to provide low-voltage assistance to the battery controller of the electric vehicle.

[0018] Optionally, the charging communication contacts of the extended controller are respectively connected to the battery controller of the electric vehicle connected to the charging gun head and the charging gun of the charging pile for transmitting charging control signals, and the charging control signals include: handshake messages and charging configuration messages.

[0019] In a second aspect, the present application provides a DC charging control method for an electric vehicle, comprising:

[0020] After the charging extender detects that at least two charging gun holders are powered on with low voltage auxiliary power, it will power on the electric vehicle with low voltage auxiliary power;

[0021] After receiving the charging handshake message CHM sent by the charging pile, the extended controller of the charging extender sends a handshake message CHM to the battery controller of the electric vehicle, and after receiving the handshake message BHM fed back by the battery controller, sends a handshake message BHM to the charging pile;

[0022] After receiving the identification message CRM regularly sent by the charging pile, the extended controller regularly sends the identification message CRM to the battery controller, and after receiving the identification message BRM fed back by the battery controller, sends the identification message BRM to the charging pile;

[0023] The extended controller sends the power battery charging parameter message BCP sent by the battery controller to the charging pile, and feeds back the time synchronization information message CTS and the maximum output capacity message CML received from the charging pile to the battery controller;

[0024] The extended controller feeds back the charging readiness message BRO sent by the battery controller to the charging pile, and receives the output readiness message CRO fed back by the charging pile;

[0025] The extended controller feeds back the BCS message and the BCL message sent by the battery controller to the charging pile, and receives the CCS message fed back by the charging pile;

[0026] The extended controller feeds back the BSM message, BMV message, BML message, and BSP message sent by the electric vehicle to the charging pile;

[0027] The extended controller feeds back the BST message sent by the electric vehicle to the charging pile, and feeds back the CST message sent by the charging pile to the electric vehicle;

[0028] The extended controller feeds back the BSD message sent by the electric vehicle to the charging pile, and sends the CSD message fed back by the charging pile to the electric vehicle.

[0029] Optionally, after the extended controller receives the BCL message sent by the battery controller, the method further includes:

[0030] When the demand current of the electric vehicle is greater than or equal to the maximum input current of the main charging gun socket among the at least two charging gun sockets, the extended controller sends a BCL message to the charging pile through the at least two charging gun sockets respectively, and the current demand contained in the BCL message is half of the original demand;

[0031] When the required current is less than the maximum input current of the main charging gun socket among the at least two charging gun sockets, the extended controller sends different BCL messages to the charging pile through the at least two charging gun sockets respectively, wherein the content of the BCL message sent to the charging pile through the main charging gun socket is consistent with the original BCL message.

[0032] Optionally, before the extended controller receives the BRM message sent by the battery controller, the method further includes:

[0033] The expansion controller sends a 0x00 confirmation code to the battery controller;

[0034] After the battery controller receives the 0x00 confirmation code from the extension controller, the extension controller receives the CRM message sent by the battery controller;

[0035] After receiving the identification message CRM, the confirmation code of the expansion controller becomes 0xAA.

[0036] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0037] The present application provides a DC charging extender and control method for an electric vehicle. By using the DC charging extender, multiple charging guns can be used to charge the electric vehicle at the same time, and an ordinary fast charging pile can be used to achieve the effect of a super charging pile, thereby increasing the charging speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A schematic diagram of the structure of a DC charging extender for an electric vehicle provided in an embodiment of the present application;

[0040] Figure 2 A schematic diagram of a DC charging extender circuit for an electric vehicle provided in an embodiment of the present application;

[0041] Figure 3 A schematic flow chart of a DC charging control method for an electric vehicle provided in an embodiment of the present application. DETAILED DESCRIPTION

[0042] The following will be combined with 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 only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0043] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0044] The embodiment of the present application provides a DC charging extender for an electric vehicle, comprising: a charging gun head, at least two charging gun seats, and an extended controller. Among them, the DC contacts of all charging gun seats are connected in parallel to the DC contacts of the charging gun head; the grounding contacts of all charging gun seats are connected in parallel to the grounding contacts of the charging lead; the charging gun seat includes a main charging gun seat and at least one secondary charging gun seat, and the charging connection confirmation contact of the main charging gun seat is connected to the charging connection confirmation contact of the charging gun head; one of the charging connection confirmation contacts of all secondary charging gun seats is connected to the grounding contact of the charging gun head through a resistor, and the other contact is left vacant; the charging communication contacts and low-voltage auxiliary contacts of all charging gun seats, as well as the charging communication contacts and low-voltage auxiliary contacts on the charging gun head are connected to the corresponding charging communication contacts and low-voltage auxiliary contacts on the extended controller.

[0045] In the embodiment of the present application, the charging gun holders are respectively used to connect external charging gun heads, wherein the external charging gun heads may be charging gun heads that are not charging piles, or multiple charging gun heads of the same charging pile, wherein the charging pile of the external charging gun head connected to the main charging gun holder is used to confirm the charging connection with the electric vehicle. In this embodiment, the charging gun head is connected to the battery controller of the electric vehicle, and the charging pile inputs a DC current through the charging gun holder and outputs it to the battery of the electric vehicle for charging.

[0046] refer to Figure 1 As shown, the present application provides a DC charging extender for an electric vehicle, comprising: a charging gun head, a first charging gun socket, a second charging gun socket and an extension controller, wherein the charging gun head is connected to the first charging gun socket and the second charging gun socket respectively, and the charging gun head, the first charging gun socket and the second charging gun socket are respectively connected to the extension controller.

[0047] In an embodiment of the present application, the DC charging extender of the electric vehicle is connected to the external charging gun of the first charging pile and the external charging gun of the second charging pile through the first charging gun holder and the second charging gun holder, respectively, and the power input from the first charging pile and the second charging pile is concentrated to the charging gun head, and output to the battery of the electric vehicle. In this embodiment, before the first charging gun holder and the second charging gun holder output the electric energy of the first charging pile and the second charging pile to the charging gun head, it is further necessary to realize the charging communication connection between the first charging pile and the second charging pile and the electric vehicle through the expansion controller. After the charging communication connection is established, the first charging pile and the second charging pile are controlled to charge the electric vehicle through a charging gun head, and the ordinary fast charging pile is used to achieve the effect of the super charging pile, thereby increasing the charging speed.

[0048] refer to Figure 2As shown, in an exemplary embodiment, the charging gun head in the DC charging extender of the electric vehicle has 9 contacts, namely DC+-0, DC--0, CC1-0, CC2-0, PE-0, S+-0, S--0, A+-0, A--0; the first charging gun holder has 9 contacts, namely: DC+-1, D--1, CC1-1, CC2-1, PE-1, S+-1, S--1 , A+-1, A--1; the second charging gun holder has 9 contacts, namely: DC+-2, DC--2, CC1-2, CC2-2, PE-2, S+-2, S--2, A+-2, A--2; the extension controller has S+-1, S--1, A+-1, A--1, S+-2, S--2, A+-2, A--2, S+-0, S--0, A+-0, A--0 and other contacts.

[0049] In the embodiment of the present application, the DC contacts DC+-1 and DC--1 of the first charging gun holder and the DC contacts DC+-2 and DC--2 of the second charging gun holder are respectively connected to the DC contacts DC+-0 and DC--0 of the charging gun head, and the DC contacts DC+-0 and DC--0 of the charging gun head are used to perform DC charging to the electric vehicle. In this embodiment, the first charging pile collects the respective DC power through the contacts DC+-0 and DC--0 to the charging gun head through the DC contacts DC+-1 and DC--1 of the first charging gun holder, and the second charging pile collects the respective DC power through the contacts DC+-0 and DC--0 to the charging gun head through the DC contacts DC+-2 and DC--2 of the second charging gun holder, thereby realizing DC charging of the electric vehicle.

[0050] In the embodiment of the present application, the grounding contact PE1 of the first charging gun holder and the grounding contact PE2 of the second charging gun holder are respectively connected to the grounding contact PE0 of the charging gun head, and are used to be connected to the vehicle ground through the grounding contact PE0 of the charging gun head. In this embodiment, the first charging pile and the second charging pile are further connected to the ground of the electric vehicle through the grounding contacts PE1 and PE2 and the grounding contact PE0 of the charging gun head, respectively, so that the first charging pile and the second charging pile are connected to the electric vehicle ground during the charging process.

[0051] In an embodiment of the present application, the charging confirmation contacts CC1-1 and CC2-1 of the first charging gun holder are connected to the charging confirmation contacts CC1-0 and CC2-0 of the charging gun head to confirm that the external charging gun of the first charging pile has been connected to the first charging gun holder, and the charging gun has been connected to the charging gun holder of the electric vehicle. In this embodiment, the first charging pile connected to the first charging gun holder is connected to the battery controller of the electric vehicle through the charging confirmation contacts CC1-1 and CC2-1 and the charging confirmation contacts CC1-0 and CC2-0 of the charging gun head for charging confirmation. In an embodiment of the present application, the charging confirmation contact CC1-2 of the second charging gun holder is connected to the ground contact PE0 through a resistor R, and the charging confirmation interface CC2-2 of the second charging gun holder is vacant.

[0052] In an exemplary embodiment, when an electric vehicle is charged by more than two charging piles, it is necessary to clearly identify the charging pile that communicates with the electric vehicle for charging. Therefore, the present application grounds the charging confirmation contacts of other charging gun holders except the first charging gun holder, thereby achieving charging confirmation between only the first charging pile and the battery controller of the electric vehicle.

[0053] In the embodiment of the present application, the low-voltage auxiliary contacts A+-1 and A--1 of the first charging gun holder are respectively connected to the low-voltage auxiliary contacts of the external charging gun of the first charging pile and the low-voltage auxiliary contacts A+-1 and A--1 of the extended controller; the low-voltage auxiliary contacts A+-2 and A--2 of the second charging gun holder are respectively connected to the low-voltage auxiliary contacts of the external charging gun of the second charging pile and the low-voltage auxiliary contacts A+-2 and A-2 of the extended controller; the low-voltage auxiliary contacts A+-0 and A--0 of the extended controller are connected to the low-voltage auxiliary contacts A+-0 and A--0 of the charging gun head to provide low-voltage assistance for the battery controller of the electric vehicle. In this embodiment, after the two low-voltage auxiliary circuits are connected to the extended controller, one of them is connected to A+-0 and A--0 to provide low-voltage assistance for the vehicle battery controller; the other provides low-voltage assistance for the extended controller.

[0054] In an embodiment of the present application, the charging communication contacts S+-0, S--0, S+-1, S--1, S+-2, and S--2 of the extended controller are respectively connected to the battery controller of the electric vehicle connected to the charging gun head, the external charging gun of the first charging pile, and the external charging gun of the second charging pile to transmit charging control signals, and the charging control signals include: handshake messages and charging configuration messages.

[0055] refer to Figure 3 As shown, the present application provides a DC charging control method for an electric vehicle, comprising:

[0056] After detecting that the first charging gun holder and the second charging gun holder are powered on by low voltage auxiliary power, the charging extender performs low voltage auxiliary powering on the electric vehicle;

[0057] In an embodiment of the present application, after the electric vehicle is physically connected to two charging piles and a charging gun through a charging extender, the low-voltage auxiliary of the two charging guns is powered on, and the charging extender powers on the low-voltage auxiliary (A+-0, A--0) of the car battery, ultimately realizing the low-voltage auxiliary of the two charging piles for the electric vehicle.

[0058] After receiving the charging handshake message CHM sent by the first charging pile and the second charging pile, the extended controller of the charging extender sends a handshake message CHM to the battery controller of the electric vehicle, and after receiving the handshake message BHM fed back by the battery controller, sends a handshake message BHM to the first charging pile and the second charging pile;

[0059] In the embodiment of the present application, the first charging pile and the second charging pile send a handshake message CHM to the extended controller through S+-1, S-1 and S+-2, S--2 respectively, wherein the CHM message only contains the communication protocol version number. The extended controller sends a CHM message with the same content as the CHM message sent by the first charging pile to the battery controller of the electric vehicle. After receiving the CHM message, the battery controller of the electric vehicle sends a handshake message BHM containing only the "maximum allowed total charging voltage" to the extended controller, and the extended controller feeds back the handshake message BHM to the first charging pile and the second charging pile.

[0060] After receiving the identification message CRM regularly sent by the first charging pile and the second charging pile, the extended controller regularly sends the identification message CRM to the battery controller, and after receiving the identification message BRM fed back by the battery controller, sends the identification message BRM to the first charging pile and the second charging pile;

[0061] In an embodiment of the present application, in order to confirm whether the communication link between the charging pile, the charging extender and the battery controller is correct, the charging pile controller periodically sends a charging pile identification message CRM to the extended controller. In this embodiment, before receiving the extended controller identification message CRM, the confirmation code of the charging pile = 0x00, and after receiving the extended controller identification message CRM, the confirmation code of the charging pile = 0xAA. The extended controller regularly sends the CRM messages sent by the two charging piles to the battery controller of the electric vehicle. Before receiving the battery controller identification message, the confirmation code of the extended controller = = 0x00; after receiving the battery controller identification message, the confirmation code of the extended controller = 0xAA. Further, after the battery controller receives the 0x00 confirmation code of the extended controller, it regularly sends the battery controller identification message BRM to the extended controller until the 0xAA confirmation code of the extended controller is received within 5s. Further, the extended controller sends the received battery controller identification message BRM to the two charging piles. In this embodiment, the content of the BRM message is vehicle identification information, including protocol version, battery type, capacity, battery voltage, battery pack serial number, battery pack production date, battery pack charge times, VIN code, BMS version number, etc.

[0062] The extended controller sends the power battery charging parameter message BCP sent by the battery controller to the first charging pile and the second charging pile, and feeds back the time synchronization information message CTS and the maximum output capacity message CML received from the first charging pile and the second charging pile to the battery controller;

[0063] In an embodiment of the present application, the battery controller sends a power battery charging parameter message BCP to the extended controller, wherein the BCP message information includes the maximum allowable charging voltage of the single cell, the maximum allowable total charging voltage, the maximum allowable charging current, the nominal total energy, the maximum allowable temperature, SOC, the current battery voltage of the power battery of the whole vehicle, etc. The extended controller copies the BCP message to the first charging pile and the second charging pile, and sends the time synchronization information message CTS and the charger maximum output capacity message CML received from the two charging piles to the battery controller of the electric vehicle. The content of the CTS message is consistent with the CTS message of the first charging pile, and the content of the CML message is the sum of the maximum output capacities of the first charging pile and the second charging pile.

[0064] The extended controller feeds back the charging readiness message BRO sent by the battery controller to the first charging pile and the second charging pile, and receives the output readiness message CRO fed back by the first charging pile and the second charging pile;

[0065] In an embodiment of the present application, after the battery controller and the charging pile respectively confirm that there is no problem with the above-mentioned message, the battery controller of the electric vehicle sends a message BRO SPN2829=0X00 indicating that the battery controller is ready to charge (indicating that charging is not ready), and starts the entire charging system detection, and then sends the battery controller charging ready message BRO SPN2829=0XAA (indicating that charging is ready).

[0066] The extended controller sends the battery controller charging ready message BRO sent by the battery controller to the first charging pile and the second charging pile. The two charging piles send the charging pile output ready message CRO SPN2830=0X00, indicating that the charger has not completed the charging preparation. The charging pile controller starts the charging preparation, and then sends the charger output ready message CROSPN2830=0XAA. After that, the two charging piles start to control the charging of the electric vehicle.

[0067] The extended controller feeds back the BCS message and the BCL message sent by the battery controller to the first charging pile and the second charging pile, and receives the CCS message fed back by the first charging pile and the second charging pile;

[0068] In the embodiment of the present application, the BCS message sent by the battery controller includes the charging voltage, charging current, maximum single cell voltage, SOC, and estimated remaining time of the power battery pack. The sent BCL message includes voltage demand, power demand and charging mode, etc. In this embodiment, when the demand current is greater than or equal to the maximum output current of the first charging pile, the extended controller sends a BCL message to the first charging pile and the second charging pile, wherein the content of the BCL message is voltage demand (original value unchanged), current demand (original value*0.5), and charging mode (original value unchanged); when the demand current is less than the maximum output current of the first charging pile, the extended controller sends different BCL messages to the first charging pile and the second charging pile, wherein the BCL message sent to the first charging pile is the same as the BCL message sent by the battery controller to the extended controller, and the message demand current sent to the second charging pile is 0. In this embodiment, the first charging pile and the second charging pile send CCS messages to the extended controller respectively, wherein the CCS message information includes the output voltage, output current, cumulative charging time, charging permission or suspension, etc. of the charging module. The extended controller further sends a CCS message to the battery controller, the content of which is the output voltage (the output voltage of the first charging pile), the output current (the sum of the output currents of the first charging pile and the second charging pile), the accumulated charging time (the first charging pile), and charging allowed or suspended (as long as one of the first charging pile and the second charging pile is suspended).

[0069] The extended controller feeds back the BSM message, BMV message, BML message, and BSP message sent by the electric vehicle to the first charging pile and the second charging pile;

[0070] In an embodiment of the present application, during the process of charging the electric vehicle, the electric vehicle will also periodically send a BSM message to the extended controller. The BSM message contains the battery status information, and its specific message format is as follows, including: the number of the highest single power battery voltage, the highest power battery temperature, the highest temperature detection point number, the lowest power battery temperature, the lowest temperature detection point number, the single power battery voltage is too high / too low / normal, the SOC is too high / too low / normal, the charging current is normal / overcurrent / untrusted state, the temperature is too high / normal / untrusted state, the insulation state is normal / abnormal / untrusted state, the output connector state is normal / abnormal / untrusted state, and charging is allowed / prohibited. In this embodiment, during the charging process, the electric vehicle can also selectively send BMV, BML, and BSP messages to the extended controller, wherein the BMV message gives the voltage value of each single power battery, the BML gives the temperature of each single power battery, and the BSP is a power battery reserved message.

[0071] The extended controller feeds back the BST message sent by the electric vehicle to the first charging pile and the second charging pile, and feeds back the CST message sent by the first charging pile and / or the second charging pile to the electric vehicle;

[0072] The extended controller feeds back the BSD message sent by the electric vehicle to the first charging pile and the second charging pile, and sends the CSD messages fed back by the first charging pile and the second charging pile respectively to the electric vehicle.

[0073] In an embodiment of the present application, after charging stops between the charging pile and the battery controller, the charging end stage is entered. In this stage, the battery controller of the electric vehicle segment sends a BSD message to the extended controller, and the extended controller sends the BSD message to the first charging pile and the second charging pile as it is. At the same time, the CSD message fed back by the first charging pile and the second charging pile is received, wherein the content of the CSD message includes information such as the output power and the accumulated charging time during the entire charging process. During the entire charging process, the output circuit is the sum of the output power of the first charging pile and the second charging pile, and the accumulated charging time is the same as the accumulated charging time of the first charging pile.

[0074] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A DC charging extender for an electric vehicle, characterized in that: The DC charging extender comprises: A charging gun head, used to connect to the charging gun holder of an electric vehicle; At least two charging gun holders, used to connect to the charging guns of the charging pile; The extended controller is electrically connected to the charging gun head and the at least two charging gun seats respectively, and is used to control the at least two charging gun seats to receive the electric energy input by the charging pile, and charge the electric vehicle through the charging gun head.

2. The DC charging extender for electric vehicles according to claim 1, characterized in that: The DC contacts of the at least two charging gun seats are respectively connected to the DC contacts of the charging gun head, so as to perform DC charging on the electric vehicle through the DC contacts of the charging gun head.

3. The DC charging extender for electric vehicles according to claim 1, characterized in that: The grounding contacts of the at least two charging gun sockets are respectively connected to the grounding contacts of the charging gun head, so as to be connected to the vehicle ground through the grounding contacts of the charging gun head.

4. The DC charging extender for electric vehicles according to claim 1, characterized in that: The charging confirmation contact of the main charging gun seat of the at least two charging gun seats is connected to the charging confirmation contact of the charging gun head to confirm that the charging gun of the charging pile has been connected to the main charging gun seat and the charging gun has been connected to the charging gun seat of the electric vehicle.

5. The DC charging extender for electric vehicles according to claim 1, characterized in that: The first charging confirmation contact of the secondary charging gun seat of the at least two charging gun seats is connected to the ground contact of the charging gun head through a resistor, and the second charging confirmation interface of the secondary charging gun seat is vacant.

6. The DC charging extender for electric vehicles according to claim 1, characterized in that: The low-voltage auxiliary contact of the main charging gun seat of the at least two charging gun seats is respectively connected to the low-voltage auxiliary contact of the charging gun of the charging pile and a low-voltage auxiliary contact of the extended controller; The low-voltage auxiliary contacts of the secondary charging gun seats of the at least two charging gun seats are respectively connected to the low-voltage auxiliary contacts of the charging gun of the charging pile and a low-voltage auxiliary contact of the extended controller; A low-voltage auxiliary contact of the extended controller is connected to the low-voltage auxiliary contact of the charging gun head, and is used to provide low-voltage assistance to the battery controller of the electric vehicle.

7. The DC charging extender for electric vehicles according to claim 1, characterized in that: The charging communication contacts of the extended controller are respectively connected to the battery controller of the electric vehicle connected to the charging gun head and the charging gun of the charging pile for transmitting charging control signals, and the charging control signals include: handshake messages and charging configuration messages.

8. A DC charging control method for an electric vehicle, characterized in that: The DC charging control method comprises: After the charging extender detects that at least two charging gun holders are powered on with low voltage auxiliary power, it will power on the electric vehicle with low voltage auxiliary power; After receiving the charging handshake message CHM sent by the charging pile, the extended controller of the charging extender sends a handshake message CHM to the battery controller of the electric vehicle, and after receiving the handshake message BHM fed back by the battery controller, sends a handshake message BHM to the charging pile; After receiving the identification message CRM regularly sent by the charging pile, the extended controller regularly sends the identification message CRM to the battery controller, and after receiving the identification message BRM fed back by the battery controller, sends the identification message BRM to the charging pile; The extended controller sends the power battery charging parameter message BCP sent by the battery controller to the charging pile, and feeds back the time synchronization information message CTS and the maximum output capacity message CML received from the charging pile to the battery controller; The extended controller feeds back the charging readiness message BRO sent by the battery controller to the charging pile, and receives the output readiness message CRO fed back by the charging pile; The extended controller feeds back the BCS message and the BCL message sent by the battery controller to the charging pile, and receives the CCS message fed back by the charging pile; The extended controller feeds back the BSM message, BMV message, BML message, and BSP message sent by the electric vehicle to the charging pile; The extended controller feeds back the BST message sent by the electric vehicle to the charging pile, and feeds back the CST message sent by the charging pile to the electric vehicle; The extended controller feeds back the BSD message sent by the electric vehicle to the charging pile, and sends the CSD message fed back by the charging pile to the electric vehicle.

9. The DC charging control method for an electric vehicle according to claim 10, characterized in that: After the extended controller receives the BCL message sent by the battery controller, the method includes: When the demand current of the electric vehicle is greater than or equal to the maximum input current of the main charging gun socket among the at least two charging gun sockets, the extended controller sends a BCL message to the charging pile through the at least two charging gun sockets respectively, and the current demand contained in the BCL message is half of the original demand; When the required current is less than the maximum input current of the main charging gun socket among the at least two charging gun sockets, the extended controller sends different BCL messages to the charging pile through the at least two charging gun sockets respectively, wherein the content of the BCL message sent to the charging pile through the main charging gun socket is consistent with the original BCL message.

10. The DC charging control method for an electric vehicle according to claim 8, characterized in that: Before the extended controller receives the BRM message sent by the battery controller, the method further includes: The expansion controller sends a 0x00 confirmation code to the battery controller; After the battery controller receives the 0x00 confirmation code from the extension controller, the extension controller receives the CRM message sent by the battery controller; After receiving the identification message CRM, the confirmation code of the expansion controller becomes 0xAA.

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