A Plug-in Hybrid Vehicle V2V DC Charging System and Control Method

Abstract

The present invention provides a V2V DC charging system for a plug-in hybrid vehicle, comprising: a charging connection device, a discharging vehicle and a charging vehicle; firstly, after the charging connection device completes the connection between the discharging vehicle and the charging vehicle, the discharging vehicle is woken up first to enable the discharging vehicle to complete high-voltage power-on; the discharging vehicle sends its own maximum output capacity and a discharging ready signal to the charging connection device through CAN communication; the charging connection device wakes up the charging vehicle based on the discharging ready signal to enable the charging vehicle to complete high-voltage power-on; the charging connection device then simulates a charging pile to perform a charging handshake and charging parameter configuration with the charging vehicle according to a preset standard; after the charging vehicle is ready, the discharging vehicle drives a generator to generate electricity through an engine to charge the power battery of the charging vehicle.

Description

Technical Field

[0001] The present invention relates to the field of vehicle-to-vehicle (V2V) discharging, and particularly to a V2V DC charging system and control method for a plug-in hybrid vehicle. Background Art

[0002] With the worsening of the global energy crisis, the national policy support for the development of new energy vehicles, and the development of the new energy vehicle market over the years, new energy vehicles have been continuously popularized, and the proportion in the national motor vehicle ownership has been continuously increasing. By the end of 2021, the national ownership of new energy vehicles reached 7.84 million. The public's awareness and acceptance of new energy vehicles have been continuously improving. According to surveys, the driving range and charging convenience are still the primary considerations for most consumers when purchasing new energy vehicles.

[0003] However, limited by the current power battery technology, the driving range of new energy vehicles still cannot achieve a qualitative breakthrough; although the country has increased the construction of charging infrastructure in recent years, it still cannot be as convenient as fuel vehicles, and there is even zero coverage in many areas.

[0004] Based on these factors, there is an urgent need to design a charging method that is convenient for roadside rescue, so as to provide an emergency power supply for consumers when the battery runs out but there are no charging facilities nearby, and ensure that they can drive to a safe or convenient charging area. Summary of the Invention

[0005] In view of this, the present invention provides a V2V DC charging system and control method for a plug-in hybrid vehicle, which can directly use fuel from the original vehicle's generator to directly charge the charging vehicle without using the power of the power battery and without using an on-board charger with reverse output, can realize remote reinforcement work, and can also improve the conversion efficiency.

[0006] The present invention provides a V2V DC charging system for a plug-in hybrid vehicle, including: a charging connection device, a discharging vehicle, and a charging vehicle;

[0007] First, after the charging connection device completes the connection between the discharging vehicle and the charging vehicle, it first wakes up the discharging vehicle to make the discharging vehicle complete high-voltage power-on;

[0008] The discharging vehicle sends its own maximum output capacity and discharging ready signal to the charging connection device through CAN communication;

[0009] The charging connection device wakes up the charging vehicle based on the discharging ready signal to make the charging vehicle complete high-voltage power-on;

[0010] The charging connection device then simulates a charging pile to perform charging handshaking and charging parameter configuration with the charging vehicle according to a preset standard;

[0011] After the charging vehicle is ready, the discharging vehicle uses the power provided by the engine to drive the generator to generate electricity to charge the power battery of the charging vehicle.

[0012] Preferably, the discharging vehicle is equipped with an engine, a generator, a vehicle controller 1, an inverter, a DC charging port A, a battery management system 1, and a power battery 1;

[0013] The charging vehicle is equipped with a vehicle controller 2, a DC charging port B, a battery management system 2, and a power battery 2;

[0014] The inverter is connected to the power battery 1 through a main relay 1, and the DC charging port A is connected to the inverter and the main relay 1 through a fast charging relay 1;

[0015] The DC charging port B is connected to the main relay 2 through a fast charging relay 2;

[0016] The charging connection device includes a discharging gun head for connecting to the DC charging port A of the discharging vehicle, a charging gun head for connecting to the DC charging port B of the charging vehicle, high and low voltage cables for connecting the DC charging port A and the DC charging port B, a power supply module for providing low voltage auxiliary power supply to the charging vehicle and the discharging vehicle, and a charging connection control module for detecting the connection state of the charging and discharging gun heads, collecting the temperatures of the charging and discharging gun heads, and controlling the unlocking and locking of the charging electronic locks of the charging and discharging vehicles.

[0017] Preferably, the resistance value of the CC2 resistor configured in the discharging gun head is different from the resistance value of the CC2 resistor specified in the preset standard, and the resistance value of the CC2 resistor configured in the charging gun head is equal to the resistance value of the CC2 resistor specified in the preset standard.

[0018] Preferably, after the vehicle controller 1 of the discharging vehicle is awakened by the charging connection device, it controls the battery management system 1 to detect the CC2 resistor. If it is determined that the discharging vehicle has a discharging requirement and is fully connected to the discharging gun head based on the detected CC2 resistor, the vehicle controller 1 of the discharging vehicle controls the discharging vehicle to complete high-voltage power-on;

[0019] After the discharging vehicle completes high-voltage power-on, the vehicle controller 1 controls the generator to start the engine by dragging the energy of the power battery 1. After the engine starts, the vehicle controller 1 controls the generator to generate electricity using the energy of the engine. The target voltage of the generator is a preset voltage greater than the total voltage of the power battery 1, and the target power of the generator is the low-voltage consumption power of the discharging vehicle;

[0020] After the generator generates electricity normally, the vehicle controller 1 controls the main relay 1 connected to the power battery 1 to disconnect; thereafter, the battery management system 1 determines again whether the state of the power generation vehicle meets the preset discharge condition. If it meets, it sends a discharge ready signal to the charging connection device through the CAN bus and sends the maximum output capacity of the discharging vehicle to the charging connection device;

[0021] Based on the discharge ready signal, the charging connection control device wakes up the charging vehicle and simulates the charging handshake and charging parameter configuration between the charging pile and the charging vehicle;

[0022] Meanwhile, the charging connection device sends the detected DC voltage at the charging end to the battery management system 1 through the CAN bus. The battery management system 1 forwards this to the vehicle controller 1, and the vehicle controller 1 adjusts the power generation target voltage of the generator to the DC voltage at the charging end;

[0023] When the charging connection device determines that the absolute value of the difference between the actual bus voltages at the discharging vehicle end and the charging vehicle end is within the preset range, it controls the charging relay to close, and the discharging vehicle starts to charge the charging vehicle;

[0024] During the charging process, the charging connection device sends the received charging demand to the battery management system 1 through the CAN bus in real time. The battery management system 1 forwards it to the vehicle controller 1, so that the vehicle controller 1 adjusts the output current and output voltage of the generator according to the charging demand.

[0025] Preferably, the charging connection control device wakes up the charging vehicle based on the discharge ready signal. Meanwhile, it locks the electronic locks of the charging gun head and the discharging gun head and simulates the charging pile to start the charging handshake with the battery management system 2 of the charging vehicle;

[0026] After the battery management system 2 of the charging vehicle is woken up, it detects the CC2 resistance. If it determines that the charging vehicle has a charging demand and is fully connected to the charging gun head according to the detected CC2 resistance, it controls the discharging vehicle to complete the high-voltage power-on through the vehicle controller 2 of the charging vehicle;

[0027] After completing the charging handshake and high-voltage power-on, the battery management system 2 sends the maximum allowable charging capacity of the power battery 2 to the charging connection device according to the preset standard. The charging connection device then simulates the charging pile to send the maximum output capacity of the discharging vehicle to the battery management system 2;

[0028] After the battery management system 2 matches the received maximum output capacity of the discharging vehicle with its own state, it controls the fast charging relay 2 to close and then sends a charging ready signal to the charging connection device.

[0029] Preferably, when the vehicle controller 1 controls the discharging vehicle to complete the high-voltage power-on, the main relay 1 closes and the fast charging relay 1 disconnects;

[0030] When the vehicle controller two controls the charging vehicle to perform high-voltage power-on, the main relay two closes and the fast charging relay two disconnects.

[0031] Preferably, after entering the DC charging state, if charging is completed, the user actively terminates charging, or a fault requiring termination of charging occurs in the charging or discharging vehicle, the vehicle controller one of the discharging vehicle controls to shut down the generator and other vehicle high-voltage loads. After the generator stops, the fast charging relay one disconnects;

[0032] After the charging vehicle determines that the charging current is lower than the preset value, the battery management system two controls the fast charging relay two to disconnect;

[0033] After the charging connection device confirms that the charging relay is disconnected, it controls the electronic locks of the charging gun and the discharging gun to unlock, and stops providing the power supply for low-voltage auxiliary power supply to the charging and discharging vehicles. The charging and discharging vehicles each complete power-off and dormancy.

[0034] The present invention also provides a V2V DC charging control method for a plug-in hybrid vehicle, including:

[0035] After the vehicle controller one of the discharging vehicle is awakened by the charging connection device, it controls the battery management system one to detect the CC2 resistance. If it is determined according to the detected CC2 resistance that the discharging vehicle has a discharging requirement and is fully connected to the discharging gun head, the vehicle controller one of the discharging vehicle controls the discharging vehicle to complete high-voltage power-on;

[0036] After the discharging vehicle completes high-voltage power-on, the vehicle controller one controls the generator to drive the engine to start by the energy of the power battery one. After the engine starts, the vehicle controller controls the generator to generate electricity using the energy of the engine. The target voltage of the generator is a preset voltage larger than the total voltage of the power battery one, and the target power of the generator is the low-voltage consumption power of the discharging vehicle;

[0037] After the generator generates electricity normally, the vehicle controller one controls the main relay one connected to the power battery one to disconnect; thereafter, the battery management system one determines again whether the state of the discharging vehicle meets the preset discharging conditions. If it meets, it sends a discharging ready signal to the charging connection device through the CAN bus, and sends the maximum output capacity of the discharging vehicle to the charging connection device;

[0038] Based on the discharging ready signal, the charging connection control device wakes up the charging vehicle and simulates the charging handshake and charging parameter configuration between the charging pile and the charging vehicle;

[0039] Based on the discharging ready signal, the charging connection control device wakes up the charging vehicle. At the same time, it locks the electronic locks of the charging gun head and the discharging gun head, and simulates the charging pile to start the charging handshake with the battery management system two of the charging vehicle;

[0040] After the battery management system II of the charging vehicle is awakened, it detects the CC2 resistor. If it is determined according to the detected CC2 resistor that the charging vehicle has a charging requirement and is fully connected to the charging gun head, the vehicle controller II of the charging vehicle is used to control the discharging vehicle to complete high-voltage power-on;

[0041] After completing the charging handshake and high-voltage power-on, the battery management system II sends the maximum allowable charging capacity of the power battery II to the charging connection device according to a preset standard, and the charging connection device then simulates the charging pile to send the maximum output capacity of the discharging vehicle to the battery management system II;

[0042] After the battery management system II matches the received maximum output capacity of the discharging vehicle with its own state, it controls the fast charge relay II to close and then sends a charging ready signal to the charging connection device;

[0043] At the same time, the charging connection device sends the detected DC voltage at the charging end to the battery management system I through the CAN bus, and the battery management system I forwards this to the vehicle controller I, and the vehicle controller I adjusts the power generation target voltage of the generator to the DC voltage at the charging end;

[0044] When the charging connection device determines that the absolute value of the difference between the actual bus voltages at the discharging vehicle end and the charging vehicle end is within a preset range, it controls the charging relay to close, and the discharging vehicle starts to charge the charging vehicle;

[0045] During the charging process, the charging connection device forwards the received charging requirement to the battery management system I through the CAN bus in real time, and the battery management system I then forwards it to the vehicle controller I, so that the vehicle controller I adjusts the output current and output voltage of the generator according to the charging requirement.

[0046] The communication messages between the discharging vehicle and the charging connection device are exchanged through a custom standard CAN, while the communication between the charging connection device and the charging vehicle adopts "GB / T 20234.3-2015 Electric vehicle conductive charging connection device Part 3: DC charging interface", and the charging handshake message also adopts "GB / T 27930-2015 Communication protocol between off-vehicle conductive chargers and battery management systems for electric vehicles" to achieve this. In this way, for the discharging vehicle, when it discharges externally and is fast-charged by the charging pile, the messages sent will not be repeated, realizing the external charging and being charged of the discharging vehicle, greatly reducing the development cost and enhancing the versatility. It realizes directly charging the charging vehicle with fuel through the original vehicle's generator without using the power battery power and without using an in-vehicle charger with reverse output, which can also achieve remote reinforcement work and improve the conversion efficiency. Brief Description of the Drawings

[0047] Figure 1 And it is a schematic diagram of the architecture of the V2V DC charging system for plug-in hybrid vehicles. Specific implementation manners

[0048] The present invention will be further described below with reference to the accompanying drawings of the specification.

[0049] As Figure 1 , the present invention provides a control system for a DC charging system of a plug-in hybrid vehicle, including: a discharging vehicle, a charging connection device, and a charging vehicle.

[0050] The discharging vehicle includes: an engine, a generator, a vehicle controller I, an inverter, a DC charging port A, a battery management system I, and a power battery I.

[0051] When the power battery I recognizes that the charging connection device has been connected and waits for the vehicle to complete high-voltage power-on, it provides energy to start the engine. The power battery I is connected to the inverter through a main relay I, and the main relay I and the inverter are connected to the DC charging port A through a fast charging relay I.

[0052] The battery management system I is used to identify the connection state of the charging connection device between the discharging vehicle and the charging gun head of the charging connection device, cooperate with the instructions of the vehicle controller I to complete the on-off of the main relay I and the fast charging relay I, and also monitor and feedback the state of the power battery I.

[0053] The generator monitors and feedbacks its own state and power generation capacity, and generates electricity according to the instructions of the vehicle controller I. The generator is connected between the engine and the inverter, and the generator has a power generation state or a driving state. When the generator is in the driving state, the direct current provided by the power battery I is rectified by the inverter into alternating current, and then supplied to the generator to start the engine; when the generator is in the power generation state, the generator generates electricity under the driving of the engine power, and then is inverted into direct current by the inverter, and then output to the DC charging port A through the fast charging relay I, or supplied to the power battery I through the main relay I for charging.

[0054] The vehicle controller I coordinates the high-voltage power-on and power-off processes of the discharging vehicle, controls the engine and the generator according to the charging requirements of the charging vehicle, feedbacks its own discharging capacity according to the state of the discharging vehicle, and controls the indicator light according to the charging state. When the charging connection device is in the connected state, it controls the vehicle to exit the drivable mode to prevent the vehicle from still being able to drive.

[0055] The engine monitors and feedbacks its own state and capacity, and works according to the instructions of the vehicle controller I.

[0056] The charging connection device monitors and feeds back its own status and capabilities. When it recognizes that both ends of the charging connection device are connected to the discharging vehicle and the charging vehicle, it wakes up the discharging vehicle and is responsible for completing the DC charging handshake process with the charging vehicle according to the "Communication Protocol between Off-vehicle Conductive Charger for Electric Vehicles and Battery Management System (GB / T 27930-2015)", and forwards the charging demand of the charging vehicle to the discharging vehicle. A "start / stop" switch can be designed on the charging connection device to manually turn on or off the discharging function.

[0057] The discharging vehicle includes: vehicle controller II, power battery II, battery management system II, and DC charging port B.

[0058] The vehicle controller II coordinates the high-voltage power-on and power-off processes of the charging vehicle and feeds back the power consumption of other loads. When the charging connection device is in the connected state, it controls the vehicle to exit the drivable mode to prevent the vehicle from being able to drive.

[0059] The power battery II stores the charging power.

[0060] The battery management system II is used to identify the connection state of the charging connection device of the charging vehicle, cooperate with the vehicle controller II to complete the on / off of the main relay II and the fast charging relay II, monitor and feed back the status of the power battery II, feed back the charging demand of the charging vehicle, and is responsible for completing the DC charging handshake process with the charging connection device according to the "Communication Protocol between Off-vehicle Conductive Charger for Electric Vehicles and Battery Management System (GB / T 27930-2015)".

[0061] The present invention provides a control method for a plug-in hybrid vehicle V2V DC charging system, including:

[0062] Step S1: Connect the discharging gun head and the charging gun head of the charging connection device to the DC charging port of the discharging vehicle and the DC charging port of the charging vehicle respectively.

[0063] Step S2: The charging connection device outputs a high level of A+ to wake up the discharging vehicle and sends a "start discharging" signal to the battery management system I of the discharging vehicle through CAN communication. The charging connection device needs to monitor its own status, such as temperature, and then calculate the maximum discharge current supported by the charging connection device according to the temperature and feed it back to the battery management system I.

[0064] Step S3: After receiving the start discharging signal, the battery management system I of the discharging vehicle detects the CC2 resistor. Once it recognizes a resistor different from the national standard CC2, it determines that the discharging vehicle has a discharging demand and has established a reliable connection with the discharging gun head of the charging connection device, and sends a "DC V2V discharging" mode to the vehicle controller I. The vehicle controller I controls the discharging vehicle to complete high-voltage power-on.

[0065] After the vehicle controller 1 determines that the discharging vehicle has completed high-voltage power-on, it judges whether the vehicle state of the discharging vehicle (such as fuel level, faults, etc.) meets the preset discharging conditions. If the preset discharging conditions are not met, it sends the vehicle discharging permission flag bit of "not allowed" to the battery management system 1. If the preset discharging conditions are met, it uses the energy of the power battery 1 to be transmitted to the inverter through the main relay 1 for inversion and then supplies power to the generator, so that the generator drives the engine to start.

[0066] After the engine starts successfully, the vehicle controller 1 controls the generator to switch to the power generation gear. The target power generation voltage of the generator is a preset value slightly larger than the total voltage of the power battery 1 (such as the total voltage of the power battery 1 + 10V), and the power generation power of the generator is the low-voltage consumption power of the discharging vehicle. After the generator generates power normally (that is, the power generation voltage of the generator 1 reaches the target power generation voltage and the power generation power reaches the low-voltage consumption power), the vehicle controller 1 controls the battery management system 1 to disconnect the main relay 1.

[0067] After that, the battery management system 1 synthesizes the maximum working capabilities of the engine, generator, and charging connection device, as well as the voltage working ranges of each high-voltage component of the discharging vehicle, and feeds back the relevant parameters (such as the maximum output voltage, minimum output voltage, maximum output current, minimum output voltage) characterizing the maximum output capability of the discharging vehicle and the DC discharging state of the discharging vehicle as a "discharging ready" signal (allowing the charging vehicle to be closed) to the charging connection device through the standard CAN.

[0068] In step S4, when the charging connection device receives the DC discharging state of the "discharging ready" signal from the battery management system 1, it outputs a high level of A+ to wake up the charging vehicle; at the same time, it locks the electronic locks of the charging gun head and the discharging gun head, starts to simulate the charging pile to send a CHM handshake message to the charging vehicle, and communicates with the charging vehicle according to the requirements of the DC charging pile in "GB / T 27930-2015".

[0069] In step S5, after the battery management system 2 of the charging vehicle is awakened, if it recognizes the national standard CC2 resistor, it sends the "DC charging" mode to the vehicle controller 2, and the vehicle controller controls the charging vehicle to complete high-voltage power-on (that is, controls the closing of the main relay 2). The charging connection device should record the protection thresholds such as the maximum allowable charging voltage, maximum allowable charging current, maximum allowable temperature, and maximum allowable single-cell voltage of the power battery 2 in the BCP message sent by the battery management system 2.

[0070] After receiving the BCP message sent by the second battery management system, the charging connection device shall send the output capabilities (maximum output voltage, minimum output voltage, maximum output current, minimum output current) of the discharging vehicle to the second battery management system of the charging vehicle through the CML message, and judge whether the charging parameters match according to the capability range of the discharging vehicle and the state of the charging vehicle. If they match, continue; if not, send "end discharge" to the first battery management system to end the discharge process.

[0071] Step S6: In step S5, after the vehicle to be charged completes high-voltage power-on, the charging connection device can collect the DC voltage at the charging end and send it to the first battery management system. The battery management system forwards it to the vehicle controller. After receiving the DC voltage at the charging end, the first vehicle controller controls the generator to enter voltage closed-loop control, with the target voltage being the DC voltage at the charging end and the power generation power being the low-voltage consumption power of the discharging vehicle.

[0072] Step S7: After the charging connection device receives BRO = 0xAA sent by the second battery management controller, it feeds back CRO = 0x00 to the second battery management controller of the charging vehicle. At the same time, it judges whether the voltage difference between the current battery voltage in the BCP message and the DC voltage at the charging end is ≤ ±5%. If so, it judges that after the high-voltage bus voltage of the charging connection device reaches within ±10V of the DC voltage of the charging vehicle and lasts for a certain period of time, it controls the charging relay to close, then sends CRO = 0xAA to the second battery management controller of the charging vehicle, and feeds back the charging relay status to the discharging vehicle; otherwise, it ends the discharge process.

[0073] Step S8: During the charging of the charging vehicle, the second battery management system sends the charging requirements (charging required voltage, charging required current, etc.) to the charging connection device through the BCL message. The charging connection device sends the V2V discharge required current and voltage to the first battery management system through the CAN signal. The first battery management system forwards it to the first vehicle controller. The first vehicle controller controls the generator to generate electricity based on this charging requirement, and the DC charging system enters the normal charging process.

[0074] Step S9. When the discharging vehicle is not allowed to discharge (such as the charging connection device is disconnected / the whole vehicle has a fault / the fuel level is low, etc.), the battery management system 1 sends a DC discharge status of "end discharge" to the charging connection device and the vehicle controller 1, so that the charging connection device sends CST; or when the charging vehicle is not allowed to charge (such as the charging connection device is disconnected / the whole vehicle has a fault / the power battery 2 is fully charged, etc.), the battery management system 2 sends a BST message to the charging connection device; or when the charging connection device monitors that the DC voltage of the discharging vehicle has reached the maximum output voltage capacity of the discharging vehicle, it sends a CST message to the battery management system 2 of the charging vehicle; or CAN communication times out; or the "start / stop" switch on the charging connection device is pressed to send CST, etc. The DC charging system then enters the termination charging process: the vehicle controller system 1 controls the generator to stop working and controls the discharging vehicle to power off under high voltage; the vehicle controller system 2 controls the charging vehicle to power off under high voltage; after the charging connection device sends a CST message to the battery management system 2 of the charging vehicle, if it exceeds 100 ms or the current is less than 5 A, it controls the charging relay to disconnect and feedbacks the charging relay status to the battery management system 1; after the charging connection device and the charging vehicle have exchanged BSD / CSD statistical messages or 10 s have passed since sending CST, it closes the A+ outputs of both the charging and discharging vehicles, unlocks the electronic locks of the charging gun head and the discharging gun head, and then enters the sleep state. After A+ is closed, the charging vehicle and the discharging vehicle enter the sleep state.

[0075] The above are only the preferred embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A plug-in hybrid vehicle V2V DC charging system, characterized in that, Including: A charging connection device, a discharging vehicle and a charging vehicle; First, after the charging connection device completes the connection between the discharging vehicle and the charging vehicle, it first wakes up the discharging vehicle to enable the discharging vehicle to complete high-voltage power-on; the communication messages between the discharging vehicle and the charging connection device are exchanged through a custom standard CAN. The discharging vehicle sends its maximum output capacity and discharging ready signal to the charging connection device through CAN communication. The charging connection device wakes up the charging vehicle based on the discharging ready signal to enable the charging vehicle to complete high-voltage power-on. The charging connection device then simulates a charging pile to perform a charging handshake and charging parameter configuration with the charging vehicle according to the preset national standard. After the charging vehicle is ready, the discharging vehicle uses the power provided by the engine to drive the generator to generate electricity to charge the power battery of the charging vehicle.

2. The plug-in hybrid vehicle V2V DC charging system according to claim 1, wherein The discharging vehicle is equipped with an engine, a generator, a vehicle controller 1, an inverter, a DC charging port A, a battery management system 1 and a power battery 1; The charging vehicle is equipped with a vehicle controller 2, a DC charging port B, a battery management system 2 and a power battery 2; The inverter is connected to the power battery 1 through a main relay 1, and the DC charging port A is connected to the inverter and the main relay 1 through a fast charging relay 1; The DC charging port B is connected to the main relay 2 through a fast charging relay 2; The charging connection device includes a discharging gun head for connecting the DC charging port A of the discharging vehicle, a charging gun head for connecting the DC charging port B of the charging vehicle, high- and low-voltage cables for connecting the DC charging port A and the DC charging port B, a power supply module for providing low-voltage auxiliary power supply for the charging vehicle and the discharging vehicle, and a charging connection control module for detecting the connection state of the charging and discharging gun, collecting the temperature of the charging and discharging gun heads, and controlling the unlocking and locking of the charging electronic locks of the charging and discharging vehicles.

3. The plug-in hybrid vehicle V2V DC charging system according to claim 2, wherein The resistance value of the CC2 resistor configured in the discharging gun head is different from the resistance value of the CC2 resistor specified in the preset standard, and the resistance value of the CC2 resistor configured in the charging gun head is equal to the resistance value of the CC2 resistor specified in the preset standard.

4. The plug-in hybrid vehicle V2V DC charging system according to claim 3, wherein After the vehicle controller 1 of the discharging vehicle is woken up by the charging connection device, it controls the battery management system 1 to detect the CC2 resistor. If it is determined according to the detected CC2 resistor that the discharging vehicle has a discharging requirement and is fully connected to the discharging gun head, the vehicle controller 1 of the discharging vehicle controls the discharging vehicle to complete high-voltage power-on; After the discharging vehicle completes high-voltage power-on, the vehicle controller 1 controls the generator to start the engine by dragging the energy of the power battery 1. After the engine starts, the vehicle controller 1 controls the generator to generate electricity using the energy of the engine. The target voltage of the generator is a preset voltage greater than the total voltage of the power battery 1, and the target power of the generator is the low-voltage consumption power of the discharging vehicle. After the generator generates electricity normally, the vehicle control unit 1 controls the main relay 1 connected to the power battery 1 to disconnect; thereafter, the battery management system 1 determines again whether the state of the discharging vehicle meets the preset discharging conditions. If it meets, it sends a discharging readiness signal to the charging connection device via the CAN bus and sends the maximum output capacity of the discharging vehicle to the charging connection device; Based on the discharging readiness signal, the charging connection device wakes up the charging vehicle and simulates the charging handshake and charging parameter configuration between the charging pile and the charging vehicle; Meanwhile, the charging connection device sends the detected DC voltage at the charging end to the battery management system 1 via the CAN bus. The battery management system 1 forwards this to the vehicle control unit 1, and the vehicle control unit 1 adjusts the power generation target voltage of the generator to the DC voltage at the charging end; When the charging connection device determines that the absolute value of the difference between the actual bus voltages at the discharging vehicle end and the charging vehicle end is within the preset range, it controls the charging relay to close, and the discharging vehicle starts to charge the charging vehicle; During the charging process, the charging connection device sends the received charging demand to the battery management system 1 via the CAN bus in real time. The battery management system 1 forwards it to the vehicle control unit 1, so that the vehicle control unit 1 adjusts the output current and output voltage of the generator according to the charging demand.

5. The plug-in hybrid vehicle V2V DC charging system according to claim 4, wherein Based on the discharging readiness signal, the charging connection device wakes up the charging vehicle. Meanwhile, it locks the electronic locks of the charging gun head and the discharging gun head and simulates the charging pile to start the charging handshake with the battery management system 2 of the charging vehicle; After the battery management system 2 of the charging vehicle is woken up, it detects the CC2 resistor. If it determines that the charging vehicle has a charging demand and is fully connected to the charging gun head according to the detected CC2 resistor, it controls the discharging vehicle to complete the high-voltage power-on through the vehicle control unit 2 of the charging vehicle; After completing the charging handshake and high-voltage power-on, the battery management system 2 sends the maximum allowable charging capacity of the power battery 2 to the charging connection device according to the preset standard. The charging connection device then simulates the charging pile to send the maximum output capacity of the discharging vehicle to the battery management system 2; After the battery management system 2 matches the received maximum output capacity of the discharging vehicle with its own state, it controls the fast charging relay 2 to close and then sends a charging readiness signal to the charging connection device.

6. The plug-in hybrid vehicle V2V DC charging system according to claim 5, wherein When the vehicle control unit 1 controls the discharging vehicle to complete the high-voltage power-on, the main relay 1 closes and the fast charging relay 1 disconnects; When the vehicle control unit 2 controls the charging vehicle to perform high-voltage power-on, the main relay 2 closes and the fast charging relay 2 disconnects.

7. The V2V DC charging system for a plug-in hybrid vehicle according to claim 4, characterized in that, After entering the DC charging state, if charging is completed, the user actively terminates charging, or a fault requiring termination of charging occurs in the charging or discharging vehicle, the vehicle control unit 1 of the discharging vehicle controls to shut down the generator and other vehicle high-voltage loads. After the generator stops, it then controls the fast charging relay 1 to disconnect; After the charging vehicle determines that the charging current is lower than the preset value, the battery management system 2 controls the fast charging relay 2 to disconnect; After confirming that the charging relay is disconnected, the charging connection device controls the electronic locks of the charging gun and the discharging gun to unlock, and stops supplying the low-voltage auxiliary power supply to the charging and discharging vehicles. The charging and discharging vehicles each complete power-off and dormancy.

8. A V2V DC charging control method for a plug-in hybrid vehicle, characterized in that, Including: After being awakened by the charging connection device, the vehicle controller 1 of the discharging vehicle controls the battery management system 1 to detect the CC2 resistance. If it is determined according to the detected CC2 resistance that the discharging vehicle has a discharging requirement and is fully connected to the discharging gun head, the vehicle controller 1 of the discharging vehicle controls the discharging vehicle to complete high-voltage power-on; After the discharging vehicle completes high-voltage power-on, the vehicle controller 1 controls the generator to start the engine by dragging with the energy of the power battery 1. After the engine starts, the vehicle controller 1 controls the generator to generate electricity using the energy of the engine. The target voltage of the generator is a preset voltage greater than the total voltage of the power battery 1, and the target power of the generator is the low-voltage consumption power of the discharging vehicle; After the generator generates electricity normally, the vehicle controller 1 controls the main relay 1 connected to the power battery 1 to disconnect; thereafter, the battery management system 1 determines again whether the state of the discharging vehicle meets the preset discharging conditions. If it meets, it sends a discharging ready signal to the charging connection device through the CAN bus, and sends the maximum output capacity of the discharging vehicle to the charging connection device; Based on the discharging ready signal, the charging connection device wakes up the charging vehicle and simulates the charging pile to perform charging handshake and charging parameter configuration with the charging vehicle according to the preset national standard; Based on the discharging ready signal, the charging connection device wakes up the charging vehicle. At the same time, it locks the electronic locks of the charging gun head and the discharging gun head, and simulates the charging pile to start the charging handshake with the battery management system 2 of the charging vehicle; After being awakened, the battery management system 2 of the charging vehicle detects the CC2 resistance. If it is determined according to the detected CC2 resistance that the charging vehicle has a charging requirement and is fully connected to the charging gun head, it controls the discharging vehicle to complete high-voltage power-on through the vehicle controller 2 of the charging vehicle; After completing the charging handshake and high-voltage power-on, the battery management system 2 sends the maximum allowable charging capacity of the power battery 2 to the charging connection device according to the preset standard, and the charging connection device then simulates the charging pile to send the maximum output capacity of the discharging vehicle to the battery management system 2; After the battery management system 2 matches the received maximum output capacity of the discharging vehicle with its own state, it controls the fast charging relay 2 to close, and then sends a charging ready signal to the charging connection device; At the same time, the charging connection device sends the detected DC voltage at the charging end to the battery management system 1 through the CAN bus, and the battery management system 1 forwards this to the vehicle controller 1, and the vehicle controller 1 adjusts the target voltage of the generator to the DC voltage at the charging end; When the charging connection device compares that the absolute value of the difference between the actual bus voltages at the discharging vehicle end and the charging vehicle end is within the preset range, it controls the charging relay to close, and the discharging vehicle starts to charge the charging vehicle; During the charging process, the charging connection device forwards the received charging requirements to Battery Management System 1 in real time via the CAN bus, and Battery Management System 1 further forwards them to Vehicle Controller 1, enabling Vehicle Controller 1 to adjust the output current and output voltage of the generator according to the charging requirements; The communication messages between the discharging vehicle and the charging connection device are exchanged via a custom standard CAN.

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