Power battery system and charging method thereof

Abstract

The invention discloses a power battery system and a charging method thereof, belongs to the technical field of electric vehicle charging, solves the problems of long charging time and difficult charging of an electric vehicle, and performs optimization design on the structure of a battery module, and then matches a reasonable battery management system. The power battery system comprises a QCBM, an SCBM1, an SCBM2, a vehicle-mounted charger and a battery management system, and can realize two charging modes: (1) the front end of the QCBM is connected with a quick charging port for quick charging, the rear end of the QCBM is connected with the SCBM1 and the SCBM2, and the QCBM performs slow charging on the SCBM1 and the SCBM2; and (2) the QCBM, the SCBM1 and the SCBM2 are all connected with a vehicle-mounted charger, a slow charging device charges each battery module through a slow charging port, and the slow charging device performs slow charging only through the vehicle-mounted charger. The purposes of short charging time, convenient charging, safe charging and prolonged service life of the battery can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric vehicle charging, and in particular relates to a power battery system and a charging method thereof. Background Art

[0002] As a key component of electric vehicles, the performance of power batteries directly affects the driving range. Battery charging issues restrict the development of electric vehicles. The biggest advantage of fast charging is its fast charging speed, which can reach 80% of the battery capacity in a short time. However, fast charging has high current and voltage, which can cause a greater impact on the battery in a short period of time, causing the battery to heat up or even cause the active material to fall off, thus affecting the battery's service life. Slow charging designs a charging curve based on battery characteristics, deeply charges the battery, improves its charging and discharging efficiency, and extends its service life, but it takes a long time to charge and is inconvenient.

[0003] In order to solve the problem of long charging time and difficulty in charging electric vehicles, the industry has proposed to use the battery swap mode to recharge electric vehicles. Electric vehicles can be quickly recharged by replacing the battery pack as a whole, replacing the battery pack in boxes, or replacing the battery pack on the move. The battery swap time is equivalent to the refueling time of fuel vehicles, which improves the convenience of charging and reduces the difficulty of charging. The advantage of the battery swap mode is that the charging speed is fast, and the power battery pack is fully charged in advance using slow charging, which is conducive to extending the battery life; the disadvantage of the battery swap mode is that it is very difficult to unify the battery structure and parameters across brands, which is not conducive to industry innovation, has high technical requirements, and the equipment cost is also high. Battery safety assurance is still a problem. Summary of the invention

[0004] The present invention mainly solves the problem of long charging time and difficulty in charging electric vehicles. Based on this, the present invention provides a power battery system and a charging method thereof. By optimizing the design of the battery module structure and matching a reasonable battery management system, the goals of short charging time, convenient charging, safe charging, extended battery life and improved driving range can be achieved.

[0005] To achieve the above object, the technical solution of the present invention is:

[0006] The present invention provides a power battery system, which includes a high-voltage control box and a power battery pack. The input end of the high-voltage control box is connected to a VCU, and the VCU is awakened through a fast charging port / slow charging port; the output end of the high-voltage control box is connected to the power battery pack, and the output end of the power battery pack is connected to a motor controller.

[0007] Based on the above technical solution, the high-voltage control box includes an on-board charger and a battery management system. The battery management system is used to monitor the battery status information of the power battery pack and send charging requirements to the VCU based on the battery status information. The VCU sends charging instructions to the on-board charger / fast charging port based on the charging requirements and charges the power battery pack.

[0008] On the basis of the above technical solution, further, the power battery pack includes QCBM, SCBM1 and SCBM2, the front end of QCBM is connected to the fast charging port, the rear end of QCBM is connected to SCBM1 and SCBM2, and QCBM, SCBM1 and SCBM2 are also connected to the on-board charger.

[0009] The present invention also provides a charging method for a power battery system, which includes a regional time-sharing slow charging stage and a regional time-sharing fast charging stage. The charging processes of the two stages are as follows:

[0010] Slow charging stage by region and time: When the charging plug is inserted into the AC charging port to wake up the VCU, the VUC sends a charging demand feedback instruction to the battery management system. After receiving the instruction, the battery management system analyzes the battery status information of QCBM, SCBM1 and SCBM2, determines whether QCBM, SCBM1 and SCBM2 need to be charged, and sends the charging demand to the VCU. After receiving the information, the VCU sends a charging instruction to the on-board charger to charge QCBM, SCBM1 and SCBM2 in sequence;

[0011] Regional and time-sharing fast charging stage: When the vehicle needs to be fast charged at a fast charging pile in a highway service area, the charging plug is inserted into the fast charging port, waking up the VCU to send feedback charging demand instructions to the battery management system. After receiving the instructions, the battery management system analyzes the battery status information of the QCBM and sends the charging demand to the VCU. After receiving the information, the VCU sends a charging instruction to the fast charging port to fast charge the QCBM.

[0012] On the basis of the above technical solution, during the regional and time-sharing fast charging stage, the front end of QCBM is connected to the fast charging port for fast charging, and during the driving of the vehicle, QCBM performs slow charging on SCBM1 and SCBM2.

[0013] Based on the above technical solution, during vehicle driving, the VCU prompts the driver to realize the cruising range of the SCBM2 or SCBM1 that is about to be discharged, and asks the driver whether it is necessary to use QCBM to slow charge the SCBM21 or SCBM2. The driver determines the choice of using QCBM to slow charge the SCBM1 or SCBM2 according to the distance to the destination.

[0014] On the basis of the above technical solution, further, when the vehicle is driving, the QCBM starts to slow charge the SCBM1, and the SCBM2 continues to discharge to the motor controller. When the power of SCBM2 is exhausted, the QCBM completes the slow charging of SCBM1. After the battery management system receives the charge status information of QCBM and SCBM2, it sends a charging request to the VCU. After receiving the request information, the VCU displays the charging request on the instrument panel through the CAN bus to prompt charging.

[0015] On the basis of the above technical solution, further, when QCBM completes fast charging and SCBM2 is exhausted, QCBM will perform slow charging on SCBM2 while the vehicle is traveling, and SCBM1 will continue to discharge to the motor controller. When SCBM2 is exhausted, QCBM completes slow charging of SCBM2. After the battery management system receives the charge status information of QCBM and SCBM1, it sends a charging request to VCU. After receiving the request information, VCU displays the charging request on the instrument panel through the CAN bus to prompt charging.

[0016] On the basis of the above technical solution, further, during the vehicle's coasting or braking process, the VCU calculates the energy recovery torque according to the current power battery status and brake pedal position signal, and sends a working state switching instruction to the motor controller through the CAN bus, starting energy recovery and driving the motor from the driving state to the power generation state.

[0017] On the basis of the above technical solution, further, during the braking energy recovery process, the driving motor consumes the kinetic energy of the wheel rotation to generate AC power, and then outputs it to the motor controller. The motor controller converts the AC power into DC power to charge the power battery and stores it in SCBM1 or SCBM2 in a non-discharge state.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The power battery system designed by the present invention includes QCBM, SCBM1, SCBM2, a vehicle charger and a battery management system. The charging circuits are designed into two types: (1) The front end of QCBM is connected to the fast charging port for fast charging, and the rear end of QCBM is connected to SCBM1 and SCBM2, and QCBM performs slow charging on SCBM1 and SCBM2; (2) QCBM, SCBM1 and SCBM2 are all connected to the vehicle charger, and the slow charging device charges each battery module through the slow charging port, and the slow charging device only performs slow charging on the vehicle charger. It can achieve the purpose of short charging time, convenient charging, safe charging and extended battery life.

[0020] 2. The power battery system designed by the present invention can realize the arbitrary switching between fast charging and slow charging. When fast charging, it is only necessary to fast charge the QCBM. During driving, the QCBM will charge the SCBM1 / SCBM2 in sequence. When the QCBM slowly charges the SCBM1, the SCBM2 supplies power to the motor controller. Until the SCBM2 is exhausted, it is only necessary to charge the QCBM in the high-speed service area, and then continue to alternately slow charge the SCBM2, and then the SCBM1 supplies power to the motor controller. It saves the parking charging time and can greatly reduce the entire charging time.

[0021] 3. The present invention can realize direct replacement of a battery module when a problem occurs, without replacing the entire battery module, thus greatly reducing the cost of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The battery structure diagram of charging and discharging in different areas and modes;

[0023] Figure 2 This is the logic diagram of slow charging control by area and time;

[0024] Figure 3 This is the logic diagram of fast charging control by area and time before charging;

[0025] Figure 4 This is the logic diagram of fast charging control in different areas and at different times during the charging process;

[0026] Figure 5 The regional and time-sharing fast charging control logic diagram for QCBM to charge SCBM1;

[0027] Figure 6 This is the regional and time-sharing fast charging control logic diagram for QCBM charging SCBM2.

[0028] Figure 7 This is the control logic diagram of the energy recovery process. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0030] 1. Structural design of power battery system

[0031] Combining the advantages of fast charging and slow charging of power batteries, they are charged in different areas, modes and times. The battery structure design is as follows: Figure 1As shown. Area division refers to dividing the power battery pack into three modules: QCBM (fast charging battery module), SCBM1 (slow charging battery module 1) and SCBM2 (slow charging battery module 2). Mode division refers to setting the charging line to two types: (1) The front end of QCBM is connected to the fast charging port for fast charging, and the back end of QCBM is connected to SCBM1 and SCBM2, and QCBM charges SCBM1 and SCBM2 slowly; (2) QCBM, SCBM1 and SCBM2 are all connected to the on-board charger, and the slow charging device charges each battery module through the slow charging port, and the slow charging device only charges the on-board charger slowly. Time sharing means that different power battery modules have different charging times, and they are charged in a certain order according to needs.

[0032] 2. Charging mode of power battery

[0033] 2.1 Slow charging by region and time

[0034] When the slow charging conditions (slow charging equipment and sufficient charging time) are met, QCBM, SCBM1 and SCBM2 all use slow charging. Figure 2 shown.

[0035] When the charging plug is inserted into the AC charging port, the VCU (Vehicle Control Unit) is awakened, and the VCU sends a feedback charging demand instruction to the BMS (Battery Management System). After receiving the instruction, the BMS analyzes the battery status information of the sensors in QCBM, SCBM1 and SCBM2, and then determines whether each module needs to be charged. The BMS feeds back the charging demand to the VCU, and the VCU sends a start charging instruction to the on-board charger after receiving the information. When charging, it is charged in sequence according to QCBM, SCBM1 and SCBM2; when discharging, it is still discharged in sequence according to QCBM, SCBM1 and SCBM2.

[0036] 2.2 Regional and time-divided fast charging

[0037] When the vehicle needs to be charged while driving but there is not enough time for slow charging, it needs to be quickly charged on a fast charging station so that charging can be completed in a shorter time.

[0038] The designed battery module discharge sequence is QCBM, SCBM1 and SCBM2. When QCBM and SCBM1 are exhausted, BMS receives the charge status information of QCBM and SCBM1, and BMS immediately sends a charging request to VCU. After receiving the request, VCU displays the charging request on the instrument panel through the CAN (Controller Area Network) bus to prompt the driver to charge. In this process, the regional and time-sharing fast charging control logic is as follows Figure 3 shown.

[0039] When the charging plug is inserted into the fast charging port of the charging pile, the VCU is awakened to send a command to the BMS to fast charge the QCBM. When the QCBM is fully charged, the fast charging is terminated. The fast charging control logic in this process is divided into different areas and times. Figure 4 shown.

[0040] When the vehicle is running, QCBM starts to slowly charge SCBM1, and SCBM2 continues to discharge to provide power for the drive motor. When SCBM2 is exhausted, QCBM completes slow charging of SCBM1. When QCBM is exhausted, SCBM1 is fully charged. In this process, the regional and time-sharing fast charging control logic is as follows: Figure 5 shown.

[0041] After receiving the charge status information of QCBM and SCBM2, BMS immediately sends a charging request to VCU. After receiving the request, VCU displays the charging request on the instrument panel through the CAN bus to prompt the driver to charge.

[0042] The QCBM is quickly charged again on the charging pile. When the vehicle is driving, the QCBM starts to slowly charge SCBM2, and SCBM1 continues to discharge to provide power for the drive motor. In this process, the regional and time-sharing fast charging control logic is as follows: Figure 6 As shown. In sequence, only QCBM is fast charged when the vehicle is parked, and only SCBM1 and SCBM2 are slow charged when the vehicle is running. During the entire driving process of the vehicle, the regional charging and discharging structure separates the charging module and the discharging module, avoiding safety risks caused by battery overheating and improving charging safety.

[0043] 2.3 Energy recovery

[0044] During the vehicle's coasting or braking process, the VCU calculates the energy recovery torque based on the current power battery status and brake pedal position signal, and sends a working state switching instruction to the motor controller via the CAN bus to start energy recovery, and the drive motor switches from the driving state to the power generation state. During the braking energy recovery process, the drive motor consumes the kinetic energy of the wheel rotation to generate AC power, which is then output to the motor controller. The motor controller converts the AC power into DC power to charge the power battery and stores it in SCBM1 or SCBM2 in a non-discharged state. The energy recovery control logic is as follows: Figure 7 shown.

[0045] 3. Perfect connection between battery module charging and discharging

[0046] In order to better solve the charging and discharging connection of the three battery modules QCBM, SCBM1 and SCBM2, the battery capacity of the three battery modules is set to be the same. Assuming that the total battery capacity of the three modules is a kWh, the theoretical cruising range is b km, and the total slow charging time of the three charging modules is t hours. Then, the battery capacities of QCBM, SCBM1 and SCBM2 are designed to be kWh, the theoretical range of each battery module is kilometers, the slow charging time of SCBM1 and SCBM2 is In this way, it can be ensured that QCBM just fully charges SCBM1 or SCBM2, and at the same driving speed v and working conditions, the slow charging time of SCBM1 and SCBM2 is equal. Of course, in order to ensure that QCBM has completed the charging task of SCBM1 (or SCBM2) before SCBM2 (or SCBM1) is discharged, it is required that the theoretical driving time of SCBM2 (or SCBM1) is not less than the time QCBM charges SCBM1 (or SCBM2), that is:

[0047] Solved,

[0048] When the driving speed does not exceed When the maximum value is reached, the charging and discharging of the three battery modules can be perfectly connected, and the maximum vehicle speed is determined by the theoretical cruising range b and the total slow charging time t of the three charging modules, which can be fully achieved when designing the battery pack.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A power battery system, characterized in that: The system includes a high-voltage control box and a power battery pack. The input end of the high-voltage control box is connected to the VCU, and the VCU is awakened through the fast charging port / slow charging port; the output end of the high-voltage control box is connected to the power battery pack, and the output end of the power battery pack is connected to the motor controller.

2. A power battery system according to claim 1, characterized in that: The high-voltage control box includes an on-board charger and a battery management system. The battery management system is used to monitor the battery status information of the power battery pack and send charging requirements to the VCU based on the battery status information. The VCU sends charging instructions to the on-board charger / fast charging port based on the charging requirements and charges the power battery pack.

3. A power battery system according to claim 2, characterized in that: The power battery pack includes QCBM, SCBM1 and SCBM2. The front end of QCBM is connected to the fast charging port, and the rear end of QCBM is connected to SCBM1 and SCBM2. QCBM, SCBM1 and SCBM2 are also connected to the on-board charger.

4. A charging method for a power battery system according to any one of claims 1 to 3, characterized in that: The charging method includes a regional time-sharing slow charging stage and a regional time-sharing fast charging stage. The charging processes of the two stages are as follows: Slow charging stage by region and time: When the charging plug is inserted into the AC charging port to wake up the VCU, the VUC sends a charging demand feedback instruction to the battery management system. After receiving the instruction, the battery management system analyzes the battery status information of QCBM, SCBM1 and SCBM2, determines whether QCBM, SCBM1 and SCBM2 need to be charged, and sends the charging demand to the VCU. After receiving the information, the VCU sends a charging instruction to the on-board charger to charge QCBM, SCBM1 and SCBM2 in sequence; Regional and time-sharing fast charging stage: When the vehicle needs to be fast charged at a fast charging pile in a highway service area, the charging plug is inserted into the fast charging port, waking up the VCU to send feedback charging demand instructions to the battery management system. After receiving the instructions, the battery management system analyzes the battery status information of the QCBM and sends the charging demand to the VCU. After receiving the information, the VCU sends a charging instruction to the fast charging port to fast charge the QCBM.

5. A charging method for a power battery system according to claim 4, characterized in that: During the regional and time-sharing fast charging stage, the front end of QCBM is connected to the fast charging port for fast charging. During the vehicle's driving, QCBM performs slow charging on SCBM1 and SCBM2.

6. A charging method for a power battery system according to claim 5, characterized in that: During vehicle driving, the VCU reminds the driver that the SCBM2 or SCBM1 that is about to be discharged has achieved the cruising range, and asks the driver whether the QCBM needs to be used to slowly charge the SCBM21 or SCBM2. The driver determines the choice of QCBM to slowly charge the SCBM1 or SCBM2 based on the distance to the destination.

7. A charging method for a power battery system according to claim 6, characterized in that: When the vehicle is driving, QCBM starts to slowly charge SCBM1, and SCBM2 continues to discharge to the motor controller. When the power of SCBM2 is exhausted, QCBM completes the slow charging of SCBM1. After the battery management system receives the charge status information of QCBM and SCBM2, it sends a charging request to VCU. After receiving the request information, VCU displays the charging request on the instrument panel through the CAN bus to prompt charging.

8. A charging method for a power battery system according to claim 7, characterized in that: When QCBM completes fast charging and SCBM2 is exhausted, QCBM will perform slow charging on SCBM2 while the vehicle is driving, and SCBM1 will continue to discharge to the motor controller. When SCBM2 is exhausted, QCBM completes slow charging of SCBM2. After receiving the charge status information of QCBM and SCBM1, the battery management system sends a charging request to the VCU. After receiving the request information, the VCU displays the charging request on the instrument panel through the CAN bus to prompt charging.

9. A charging method for a power battery system according to claim 8, characterized in that: During vehicle coasting or braking, the VCU calculates the energy recovery torque based on the current power battery status and brake pedal position signal, and sends a working state switching instruction to the motor controller through the CAN bus to start energy recovery and drive the motor from the driving state to the power generation state.

10. A charging method for a power battery system according to claim 9, characterized in that: During the braking energy recovery process, the drive motor consumes the kinetic energy of the wheel rotation to generate AC power, which is then output to the motor controller. The motor controller converts the AC power into DC power to charge the power battery and stores it in SCBM1 or SCBM2 in a non-discharge state.

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