WO2023082843A1

WO2023082843A1 - Method for controlling power system of four-wheel-drive all-electric automobile, and power system

Info

Publication number: WO2023082843A1
Application number: PCT/CN2022/120118
Authority: WO
Inventors: 刘力源; 王燕; 刘建康
Original assignee: 中国第一汽车股份有限公司
Priority date: 2021-11-15
Filing date: 2022-09-21
Publication date: 2023-05-19
Also published as: CN113954658B; CN113954658A

Abstract

A method for controlling a power system of a four-wheel-drive all-electric automobile, and a power system. The method for controlling a power system of a four-wheel-drive all-electric automobile comprises: when in a traveling operating state, acquiring a first required torque M11 used to drive a vehicle to travel, acquiring a maximum output torque M12 of a first motor (1), a sum of the maximum output torque of the first motor (1) and a maximum output torque of a second motor (2) being M13, and comparing M11, M12 and M13. In response to determining that M11 ≤ M12, a first clutch (51) is disengaged, a second clutch (52) is disengaged, and the first motor (1) outputs a torque; and in response to determining that M13 ≥ M11 > M12, the first clutch (51) is engaged, the second clutch (52) is disengaged, and the first motor (1), the second motor (2), and the third motor (3) simultaneously output torque.

Description

Power system control method and power system of four-wheel drive pure electric vehicle

This application claims priority to a Chinese patent application with application number 202111349436.8 filed with the China Patent Office on November 15, 2021, the entire contents of which are incorporated herein by reference.

technical field

The present application relates to the technical field of vehicles, for example, to a power system control method and power system of a four-wheel drive pure electric vehicle.

Background technique

In order to pursue extreme braking performance, pure electric vehicles adopt a four-wheel drive configuration and are equipped with two, three, or even four motor systems; however, users do not blindly pursue power in the actual use process, and long cruising range is also one of the main needs of users , and how to use multiple motors to meet the long cruising range is the problem to be solved in this patent. In order to meet the user's demand for power and economy at the same time, the whole vehicle needs to be equipped with more motor systems, and different driving modes must be set up. A single or multiple motors can be used to drive the vehicle through the second clutch and other devices. Power requirements also meet long-mileage requirements.

The power system of the electric vehicle and the electric vehicle with it are disclosed in the related art. The power system of the electric vehicle adopts two motors, and is equipped with a second clutch and a planetary gear, etc.; A pure electric vehicle power drive system and a vehicle, the pure electric vehicle power drive system with a power separation device includes a main drive system, an auxiliary drive system, a main power separation device and an auxiliary power separation device, etc.; For electric vehicles, the four-drive power system includes two sets of powertrains, and each set of powertrains has a motor, motor controller, reducer, etc. However, no specific control strategy is given for how to distribute torque among multiple motors in the above-mentioned patents.

Therefore, there is an urgent need for a power system control method and a power system of a four-wheel drive pure electric vehicle to solve the above problems.

Contents of the invention

The present application provides a power system control method and a power system of a four-wheel drive pure electric vehicle, so as to rationally distribute output torques of multiple motors.

In one aspect, the present application provides a power system control method of a four-wheel drive pure electric vehicle. The power system of the vehicle includes a first motor, a second motor, a third motor, a power battery, a first clutch, and a second clutch. The first A motor is in drive connection with the wheel end, the second motor is selectively in drive connection with the wheel end through the first clutch, the third motor is selectively in drive connection with the wheel end through the second clutch, and the power battery It is set to supply power to the first motor, the second motor and the third motor, and the first motor, the second motor and the third motor can respectively generate electricity and charge the power battery ; the method includes:

Obtain the current working condition of the vehicle;

performing drive torque distribution in response to determining that the current operating condition is a driving condition in which an accelerator pedal of the vehicle is depressed;

The execution of drive torque distribution includes:

Obtain the first required torque M11 for driving the vehicle;

Obtain the maximum output torque of the first motor, the second motor and the third motor respectively, and the maximum output torque of the first motor is M12, the maximum output torque of the first motor and the The sum of the maximum output torque of the two motors is M13;

Compare the size of M11, M12 and M13;

In response to determining M11≤M12, the first clutch is disengaged, the second clutch is disengaged, the first electric motor outputs torque, and the actual output torque of the first electric motor is equal to M11;

In response to determining M13≥M11>M12, the first clutch is engaged, the second clutch is disengaged, the first motor and the second motor output torque simultaneously, and the actual output torque of the first motor, the The sum of the actual output torques of the second motor is equal to M11;

In response to determining M11>M13, the first clutch is engaged, the second clutch is engaged, the first motor, the second motor and the third motor simultaneously output torque, and the actual The sum of the output torque, the actual output torque of the second motor and the actual output torque of the third motor is equal to M11.

On the other hand, the present application also provides a power system of a four-wheel drive pure electric vehicle, the power system of the four drive pure electric vehicle includes a first motor, a second motor, a third motor, a power battery, a first clutch, a second A clutch and a controller, the first motor is connected to the wheel end drive, the second motor is selectively connected to the wheel end through the first clutch, and the third motor is selectively connected to the wheel end through the second clutch. end transmission connection, the power battery is configured to supply power to the first motor, the second motor and the third motor, and the first motor, the second motor and the third motor can all generating electricity and charging the power battery;

The controller is configured to implement the power system control method of a four-wheel-drive pure electric vehicle described in any of the above solutions.

Description of drawings

Fig. 1 is a structural schematic diagram 1 of a power system of a four-wheel drive pure electric vehicle in an embodiment of the present application;

FIG. 2 is a second structural schematic diagram of a power system of a four-wheel-drive pure electric vehicle in an embodiment of the present application.

In the picture:

1. The first motor; 2. The second motor; 3. The third motor; 4. Power battery;

51. The first clutch; 52. The second clutch;

61. First motor controller; 62. Second motor controller; 63. Third motor controller; 64. Battery controller; 65. Vehicle controller; 66. Electronic stability system;

7. Rear axle; 8. Rear reducer; 9. Front axle; 10. Front reducer.

Detailed ways

In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplification of the description, rather than indicating or implying that the referred device or element must have a specific orientation, use a specific orientation construction and operation, therefore should not be construed as limiting the application. In addition, the terms "first" and "second" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance. Wherein, the terms "first position" and "second position" are two different positions, and "above", "above" and "above" the first feature on the second feature include that the first feature is on the second feature. Directly above and obliquely above, or simply means that the first feature level is higher than the second feature. "Below", "beneath" and "under" the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or simply means that the first feature has a lower level than the second feature.

In the description of this application, it should be noted that unless otherwise specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application in specific situations.

Embodiments of the present application are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary, are only for explaining the present application, and should not be construed as limiting the present application.

As shown in Figures 1-2, the present embodiment provides a power system of a four-wheel-drive pure electric vehicle, the power system of the four-wheel-drive pure electric vehicle includes a first motor 1, a second motor 2, a third motor 3, a power battery 4. The controller, the first clutch 51 and the second clutch 52, the first motor 1 and the second motor 2 are connected to the wheel end drive, the second motor 2 is selectively connected to the wheel end drive through the first clutch 51, and the third The motor 3 is selectively connected to the wheel end through the second clutch 52, the power battery 4 is set to supply power to the first motor 1, the second motor 2 and the third motor 3, and the first motor 1, the second motor 2 and the third motor The motors 3 can generate electricity and charge the power battery 4 . By controlling the engagement or disengagement of the first clutch, the second motor 2 can be connected or withdrawn from power transmission, and by controlling the engagement or disengagement of the second clutch 52, the third motor 3 can be connected or withdrawn from power transmission. Wherein, the power battery 4 includes one or more of a lithium-ion power battery, a flywheel energy storage battery system, and a fuel cell system. The models of the first motor 1 , the second motor 2 and the third motor 3 can be the same or different, and can be specifically selected according to needs.

As shown in Figures 1 and 2, the first motor 1 is connected to the rear axle 7 in transmission, the second motor 2 is selectively connected to the rear axle 7 through the first clutch 51, and the third motor 3 is selectively connected to the rear axle 7 through the second clutch 52. Front axle 9 drive connections. When the first clutch is engaged, the transmission of the second motor 2 can be connected to the rear axle 7; When the second clutch 52 is engaged, the transmission of the third motor 3 can be connected to the front axle 9;

For example, as shown in Figure 1, the power system method of a four-wheel drive pure electric vehicle also includes a rear reducer 8, the first motor 1 is connected to the rear reducer 8, and the rear reducer 8 is connected to the rear axle 7; 2 is selectively connected to the rear reducer 8 through the first clutch 51. Wherein, the first motor 1 and the second motor 2 are arranged at intervals along the left and right directions of the automobile, and the output shafts of the first motor 1 and the second motor 2 are arranged coaxially.

For example, the power system of a four-wheel-drive pure electric vehicle also includes a front speed reducer 10; connect. For example, as shown in FIG. 2 , the third motor 3 is in transmission connection with the front reducer 10 , and the second clutch 52 is arranged between the front reducer 10 and the front axle 9 .

For example, as shown in FIG. 3 and FIG. 4 , both the first motor 1 and the second motor 2 are in transmission connection with the rear axle 7 , and the third motor 3 is selectively in transmission connection with the front axle 9 through a clutch. When the clutch is engaged, the transmission of the third motor 3 can be connected to the front axle 9; For example, the power system method of a four-wheel drive pure electric vehicle also includes a front speed reducer 10, wherein, as shown in FIG. The output gear is in drive connection with the front axle 9 . As shown in FIG. 4 , the third motor 3 is in drive connection with the input gear of the front reducer 10 , and the output gear of the front reducer 10 is selectively drive connected with the front axle 9 through a clutch.

The controller includes a first motor controller 61 , a second motor controller 62 and a third motor controller 63 . Wherein, the first motor controller 61 is connected with the first motor 1 and the power battery 4, and the first motor controller 61 is set to control the magnitude of the current output by the power battery 4 to the first motor 1, and then control the actual power of the first motor 1. Output torque; at the same time, it can also control the magnitude of the current input to the power battery 4 when the first motor 1 generates power, and then control the braking torque generated by the first motor 1 . The second motor controller 62 is connected to the second motor 2 and the power battery 4, and the second motor controller 62 is configured to control the current output from the power battery 4 to the second motor 2, thereby controlling the actual output torque of the second motor 2; At the same time, the magnitude of the current input to the power battery 4 when the second motor 2 generates power can also be controlled, thereby controlling the braking torque generated by the second motor 2 . The third motor controller 63 is connected to the third motor 3 and the power battery 4, and the third motor controller 63 is configured to control the output current of the power battery 4 to the third motor 3, thereby controlling the actual output torque of the third motor 3; At the same time, the magnitude of the current input to the power battery 4 when the third motor 3 generates power can also be controlled, thereby controlling the braking torque generated by the third motor 3 . By controlling the output torques of the three motors, the magnitude of the output torque for driving the vehicle can be adjusted; by controlling the braking torque of the three motors, the magnitude of the braking torque for braking the vehicle can be adjusted.

Controller also comprises battery controller 64, and battery controller 64 is connected with power battery 4, and is set to according to the SOC (State of Charge, battery state of charge) of power battery 4, the voltage of power battery 4 and the temperature of power battery 4 Evaluate the maximum discharge power and maximum charge power of the power battery 4 . Wherein, the temperature of the power battery 4 can be collected through a temperature sensor connected to the battery controller 64, and the voltage of the power battery 4 can be collected through a voltage sensor connected to the power battery 4, and the acquisition of the SCO of the battery is a related technology, and will not be repeated here. repeat. Wherein, the voltage of the power battery 4 is the output voltage or the input voltage of the power battery 4 .

The temperature of the power battery 4, the input voltage of the power battery 4, the charging correspondence diagram of the SCO of the power battery 4 and the maximum charging power of the power battery 4 can be obtained through a large number of tests, and then according to the obtained temperature of the power battery 4, the power battery 4 The input voltage of the power battery 4 and the SOC of the power battery 4 can be queried from the above charging correspondence diagram for the maximum charging power of the corresponding power battery 4; similarly, the temperature of the power battery 4, the output voltage of the power battery 4, and the SCO and the maximum discharge power discharge correspondence diagram of the power battery 4, and then query the corresponding power battery 4 from the above discharge correspondence diagram according to the acquired temperature of the power battery 4, the output voltage of the power battery 4, and the SOC of the power battery 4 amplified discharge power.

The maximum charging current of the power battery 4 can be calculated by the maximum charging power of the power battery 4 and the input voltage of the power battery 4 . The maximum discharge current of the power battery 4 can be calculated from the maximum discharge power of the power battery 4 and the output voltage of the power battery 4 . The maximum charging current can be allocated to the first motor 1, the second motor 2 and the third motor 3 according to the first setting ratio, and then the maximum charging current of the first motor 1, the maximum charging current of the second motor 2 and the third motor can be obtained. The maximum charging current of motor 3. The maximum discharge current can be allocated to the first motor 1, the second motor 2 and the third motor 3 according to the second setting ratio, and then the maximum supply current of the first motor 1, the maximum supply current of the second motor 2 and the third The maximum supply current of motor 3. Wherein, the first setting ratio and the second setting ratio can be set as required. Taking the second setting ratio as an example, the second setting ratio may be the ratio between the rated output power of the first motor 1 , the rated output power of the second motor 2 and the rated output power of the third motor 3 .

The first motor controller 61 is also configured to evaluate the maximum output torque of the first motor 1 . For example, the first motor controller 61 acquires the first temperature of the first motor 1, the first voltage at the input end of the first motor 1, and the maximum supply current of the first motor 1, and the first motor controller 61 obtains the first temperature, The first voltage, the maximum supply current of the first motor 1 Query the corresponding first motor 1 from the map1 between the first temperature, the first voltage, the maximum supply current of the first motor 1 and the maximum output torque of the first motor 1 the maximum output torque. Among them, map1 can be obtained through a large number of previous experiments. The first motor controller 61 can obtain the temperature of the first motor 1 through the temperature sensor connected with the first motor controller 61, and obtain the first voltage of the input terminal of the first motor 1 through the voltage sensor connected with the first motor controller 61 .

The second motor controller 62 is also configured to evaluate the maximum output torque of the second motor 2 . For example, the second motor controller 62 acquires the second temperature of the second motor 2, the second voltage at the input terminal of the second motor 2, and the maximum supply current of the second motor 2, and the second motor controller 62 obtains the second temperature, The second voltage, the maximum supply current of the second motor 2 query the corresponding second motor 2 from the map2 between the second temperature, the second voltage, the maximum supply current of the second motor 2 and the maximum output torque of the second motor 2 the maximum output torque. Among them, map2 can be obtained through a large number of experiments in the early stage. The second motor controller 62 can obtain the temperature of the second motor 2 through the temperature sensor connected with the second motor controller 62, and obtain the second voltage of the input terminal of the second motor 2 through the voltage sensor connected with the second motor controller 62 .

The third motor controller 63 is configured to evaluate the maximum output torque of the third motor 3 . For example, the third motor controller 63 acquires the third temperature of the third motor 3, the third voltage at the input end of the third motor 3, and the maximum supply current of the third motor 3, and the third motor controller 63 obtains the third temperature, The third voltage, the maximum supply current of the third motor 3 Query the corresponding third motor 3 from the map3 between the third temperature, the third voltage, the maximum supply current of the third motor 3 and the maximum output torque of the third motor 3 the maximum output torque. Among them, map3 can be obtained through a large number of experiments in the early stage. The third motor controller 63 can obtain the temperature of the third motor 3 through the temperature sensor connected with the third motor controller 63, and obtain the third voltage of the input terminal of the third motor 3 through the voltage sensor connected with the third motor controller 63 .

The first motor controller 61 is also arranged to evaluate the maximum braking torque of the first motor 1 . The first motor controller 61 acquires the first temperature of the first motor 1, the first charging voltage at the output end of the first motor 1, and the maximum charging current of the first motor 1, and the first motor controller 61 according to the first temperature, the first A charging voltage, the maximum charging current of the first motor 1 Query the corresponding first Maximum braking torque of motor 1. Among them, map11 can be obtained through a large number of previous experiments. The first motor controller 61 can acquire the first voltage of the output end of the first motor 1 through a voltage sensor connected to the first motor controller 61 .

The second electric machine controller 62 is also arranged to evaluate the maximum braking torque of the second electric machine 2 . The second motor controller 62 acquires the second temperature of the second motor 2, the second charging voltage at the output end of the second motor 2, and the maximum charging current of the second motor 2, and the second motor controller 62 obtains the second temperature according to the second temperature, the second Two charging voltage, the maximum charging current of the second motor 2 query the corresponding second Maximum braking torque of motor 2. Among them, map11 can be obtained through a large number of previous experiments. The second motor controller 62 can obtain the second voltage of the output terminal of the second motor 2 through a voltage sensor connected to the second motor controller 62 .

The third motor controller 63 is also configured to evaluate the maximum braking torque of the third motor 3 . The third motor controller 63 obtains the third temperature of the third motor 3, the third charging voltage of the output terminal of the third motor 3, and the maximum charging current of the third motor 3, and the third motor controller 63 according to the third temperature, the third Three charging voltages, the maximum charging current of the third motor 3 Query the corresponding third temperature from the map11 among the third temperature, the third charging voltage, the maximum charging current of the third motor 3 and the maximum braking torque of the third motor 3 Maximum braking torque of motor 3. Among them, map11 can be obtained through a large number of previous experiments. The third motor controller 63 can obtain the third voltage of the output terminal of the third motor 3 through a voltage sensor connected to the third motor controller 63 .

The controller also includes a vehicle controller 65 . The vehicle controller 65 is respectively connected to the first clutch and the second clutch 52 to control the engagement or disengagement of the first clutch and the second clutch 52, thereby controlling whether the second motor 2 and the third motor 3 are involved in the power of the wheel end. transfer.

The whole vehicle controller 65 can also be set to judge the working condition of the current vehicle. When the brake pedal of the vehicle is stepped on, the whole vehicle controller 65 can judge that the current vehicle is in the braking condition; when the accelerator pedal of the vehicle is stepped on, The vehicle controller 65 can determine that the current vehicle is in a driving condition, that is, the vehicle is moving forward or reversing. For example, taking judging that the vehicle is in a braking condition as an example, a position sensor can be installed on the brake pedal, and the position information of the brake pedal can be obtained through the position sensor. The position information and the opening degree of the brake pedal can be set in advance in the vehicle controller 65 By querying the corresponding graph, the brake pedal opening corresponding to the position information can be obtained, and then analyzed whether the brake pedal is stepped on.

The whole vehicle controller 65 can also calculate the first wheel end demand torque of the vehicle according to the opening degree of the accelerator pedal, the vehicle speed and the rate of change of the opening degree of the accelerator pedal. Among them, the vehicle speed can be collected by the speed sensor. The change rate of the accelerator pedal opening is the change rate of the accelerator pedal position when the driver steps on the accelerator pedal, which corresponds to the target acceleration that the driver expects to accelerate to the target vehicle speed at the current moment. The ratio of the opening degree to the time when the accelerator pedal opening degree is generated is determined. The accelerator pedal opening, vehicle speed, and the rate of change of the accelerator pedal opening can be preset in the vehicle controller 65 in advance. The rate of change of the pedal opening obtains the corresponding first wheel end demand torque from the first relationship diagram. The first relationship diagram can be obtained through a large number of experiments in the early stage.

The controller also includes an electronic stability system 66. The electronic stability system 66 is connected to the vehicle controller 65. The electronic stability system 66 can calculate the maximum adhesion of multiple wheels of the vehicle according to the road surface adhesion parameters and wheel pressure parameters, and calculate the maximum adhesion according to the maximum adhesion. and the number of wheels of the vehicle to calculate the second wheel end demand torque for vehicle running. Among them, the adhesion parameter of the wheel can be characterized by the slip rate of the car, which is the degree of slippage of the car. The electronic stability system 66 can obtain the actual rotational speed of the wheel through the rotational speed sensor connected to it, and obtain the target vehicle speed of the vehicle in combination with the diameter of the wheel, then calculate the difference between the target vehicle speed and the actual vehicle speed, and then calculate the ratio of the difference to the actual vehicle speed Can be used as the slip ratio of the car. The wheel pressure parameter may be tire pressure, which can be obtained through a tire pressure sensor. In the electronic stability system 66, a relational table of road surface adhesion parameters, wheel pressure parameters and maximum adhesion can be preset in advance, and the corresponding maximum adhesion can be queried from the relational table. It should be noted that the calculation of the second wheel-side required torque for vehicle running according to the maximum adhesion force and the number of vehicle wheels is a related technology, and will not be repeated here.

It can be understood that, when the vehicle is driving on a slippery road, the driver performs a vehicle acceleration operation, and wheel slippage may occur. That is to say, at this moment, the required torque of the first wheel end is greater than the required torque of the second wheel end. If there is a slipping situation, the vehicle controller 65 distributes the required torque at the first wheel end of the automobile calculated according to the opening degree of the accelerator pedal, the vehicle speed and the rate of change of the opening degree of the accelerator pedal to multiple motors, and makes the output of the multiple motors match with it Torque will result in a waste of energy. At the same time, this also shows that the driver's driving expectations are too high for the vehicle speed, and there are safety risks, and the driver's driving expectations need to be adjusted to a safe range. Therefore, when controlling the torque output by the motor, not only the required torque of the first wheel end but also the required torque of the second wheel end should be considered. In this embodiment, the vehicle controller 65 acquires the second wheel end demand torque through the electronic stability system 66, and the vehicle controller 65 compares the first wheel end demand torque with the second wheel end demand torque, and uses the first wheel end demand torque The smaller value of the required torque and the second wheel end required torque is used as the first required torque. This can ensure driving safety and reduce the waste of electric energy of the power battery 4 . For example, when the vehicle controller 65 determines that the required torque at the first wheel end is greater than the required torque at the second wheel end, the vehicle controller 65 controls the alarm device to issue an alarm to remind the driver to pay attention to driving safety.

The vehicle controller 65 is also respectively connected with the first motor controller 61, the second motor controller 62 and the third motor controller 63, so that the vehicle controller 65 can obtain the maximum output torque of the first motor 1, the second motor 2 and the maximum output torque of the third motor 3. The first required torque is M11, the maximum output torque of the first motor 1 is M12, the vehicle controller 65 calculates the sum of the maximum output torque of the first motor 1 and the maximum output torque of the second motor 2, and the maximum output torque of the first motor 1 The sum of the output torque and the maximum output torque of the second motor 2 is M13, and the vehicle controller 65 compares the sizes of M11, M12, and M13; if M13≥M11>M12, it means that the output torque provided by the first motor 1 cannot meet the driving requirements. At least the first motor 1 and the second motor 2 are required to provide output torque at the same time, so the vehicle controller 65 needs to control the first clutch to engage and the second clutch 52 to disengage, so that the first motor 1 and the second motor 2. Provide output torque at the same time. At this time, there is no need to use the third motor 3, so as to reduce the load of the third motor 3 and improve the service life of the third motor 3; at the same time, due to the limitation of the energy conversion efficiency of the motor itself, the electric energy cannot be 100% As long as it is converted into kinetic energy, there is energy waste as long as it is used, so not using the third motor 3 at this time can avoid energy waste and prolong the mileage of the car. If M11>M13, it means that only the first motor 1, the second motor 2 and the third motor 3 can provide output torque at the same time to meet the driver's expectations, so the vehicle controller 65 needs to control the first clutch to engage and the second clutch to 52 combination, the first motor 1, the second motor 2 and the third motor 3 provide output torque at the same time. If M11≤M12, it means that only the first electric motor 1 can provide the output torque to meet the driver's driving expectation, so the vehicle controller 65 needs to control the first clutch 51 to disengage and the second clutch 52 to disengage, and there is no need to use the second electric motor at this time 2 and the third motor 3, to reduce the load of the second motor 2 and the third motor 3, improve the service life of the second motor 2 and the third motor 3; at the same time, due to the limitation of the energy conversion efficiency of the motor itself, the second motor is not used The second motor 2 and the third motor 3 can also avoid energy waste and prolong the mileage of the car.

It should be noted that the sum of the maximum output torque of the first motor 1 , the maximum output torque of the second motor 2 and the maximum output torque of the third motor 3 is greater than the first required torque in any state.

The vehicle controller 65 can also calculate the second required torque of the vehicle according to the opening of the brake pedal, the vehicle speed and the rate of change of the opening of the brake pedal. Among them, the rate of change of the brake pedal opening is the rate of change of the brake pedal position when the driver steps on the brake pedal, which corresponds to the target deceleration that the driver expects to decelerate to the target vehicle speed at the current moment, which can be determined by the brake pedal opening The ratio of the time to produce the brake pedal opening is determined. The brake pedal opening, vehicle speed, and the second relational diagram of the rate of change of the brake pedal opening and the second demand torque can be preset in the vehicle controller 65 in advance, and can be obtained according to the obtained brake pedal opening, vehicle speed and The rate of change of the opening of the brake pedal obtains the corresponding second required torque from the second relational graph. The second relationship diagram can be obtained through a large number of experiments in the early stage.

Under braking conditions, the vehicle controller 65 can also obtain the maximum braking torque of the first motor 1 and the maximum braking torque of the second motor 1 from the first motor controller 61, the second motor controller 62 and the third motor controller 63 respectively. 2 and the maximum braking torque of the third motor 3. The second required torque is M21, the maximum braking torque of the first motor 1 is M22, the vehicle controller 65 calculates the sum of the maximum braking torque of the first motor 1 and the maximum braking torque of the second motor 2, and calculates the first The sum of the maximum braking torque of the first motor 1 , the maximum braking torque of the second motor 2 and the maximum braking torque of the third motor 3 . The sum of the maximum braking torque of the first motor 1 and the maximum braking torque of the second motor 2 is M23, the maximum braking torque of the first motor 1, the maximum braking torque of the second motor 2 and the maximum braking torque of the third motor 3 The sum of the braking torques is M24. The vehicle controller 65 compares the sizes of M21, M22 and M23. If M21>M23, it means that only the first motor 1, the second motor 2 and the third motor 3 can provide braking torque at the same time to meet the driver's expectations, so the vehicle controller 65 needs to control the first clutch 51 to engage and the second The two clutches 52 are combined, and the first motor 1 , the second motor 2 and the third motor 3 provide braking torque at the same time. If M21≤M22, it means that only the first motor 1 can provide the braking torque to meet the driver's driving expectation. Therefore, the vehicle controller 65 needs to control the first clutch 51 to disengage and the second clutch 52 to disengage. At this time, there is no need to use the second Motor 2 and the 3rd motor 3, to reduce the load of the 2nd motor 2 and the 3rd motor 3, improve the service life of the 2nd motor 2 and the 3rd motor 3; The recovery efficiency of electric energy prolongs the mileage of the car. If M23≥M21>M22, it means that the braking torque provided by the first motor 1 cannot meet the driving expectation of the driver. At least the first motor 1 and the second motor 2 need to provide braking torque at the same time. The first clutch 51 is engaged and the second clutch 52 is disengaged, so that the first motor 1 and the second motor 2 provide braking torque at the same time. On the premise of ensuring the normal braking of the whole vehicle, the use of the third motor 3 is avoided to reduce the torque of the second motor. The load of the three motors 3 increases the service life of the third motor 3. At the same time, due to the limitation of the energy conversion efficiency of the third motor 3 itself, it cannot convert 100% of the kinetic energy into electric energy. As long as it is used, there is a waste of energy, so it is not used at this time. The third motor 3 can improve the recovery efficiency of electric energy and prolong the mileage of the car. For example, the vehicle controller 65 can continue to compare the sizes of M21 and M24. When M21>M24, it means that even if the three motors provide braking torque at the same time, the driver's driving expectations cannot be met, and the hydraulic brake mechanism is activated to brake the wheels. end to brake. For example, the braking torque provided by the hydraulic braking mechanism is equal to the difference between M21 and M24.

This embodiment also provides a control method for the power system of the four-wheel-drive pure electric vehicle implemented by the power system of the above-mentioned four-wheel-drive pure electric vehicle. A power system control method for a four-wheel-drive pure electric vehicle includes the following steps.

S10: Obtain the current working condition of the vehicle;

If the current working condition is a driving working condition, execute S20; if the current working condition is a braking working condition, execute S30.

S20: Execute drive torque distribution.

S30: Execute braking torque distribution.

Perform drive torque distribution including:

S21: Obtain the first required torque M11 for driving the vehicle.

The method of obtaining the first required torque for driving the vehicle includes:

Calculate the required torque at the first wheel end of the car according to the accelerator pedal opening, vehicle speed and the rate of change of the accelerator pedal opening;

Calculate the maximum adhesion force of multiple wheels of the car according to the road surface adhesion parameters and wheel pressure parameters, and calculate the second wheel end demand torque for vehicle driving according to the maximum adhesion force and the number of car wheels;

The smaller value of the first wheel-end required torque and the second wheel-end required torque is used as the first required torque.

S22: Obtain the maximum output torque of the first motor 1, the second motor 2 and the third motor 3 respectively, and the maximum output torque of the first motor 1 is M12, the maximum output torque of the first motor 1 and the maximum output torque of the second motor 2 The sum of output torque is M13.

For example, the method for obtaining the maximum output torque of the first motor 1 includes: obtaining the first temperature of the first motor 1, the first voltage of the input terminal of the first motor 1, and the maximum supply current of the first motor 1, the first motor 1 The maximum supply current of the first motor 1 according to the first temperature, the first voltage, the maximum supply current of the first motor 1 from the map1 between the first temperature, the first voltage, the first maximum supply current and the maximum output torque of the first motor 1 Query the corresponding maximum output torque of the first motor 1 .

The method for obtaining the maximum output torque of the second motor 2 includes: obtaining the second temperature of the second motor 2, the second voltage of the input terminal of the second motor 2, the maximum supply current of the second motor 2, and the maximum The power supply current, according to the second temperature, the second voltage, and the maximum power supply current of the second motor 2, query the correspondence between the second temperature, the second voltage, the second maximum power supply current and the maximum output torque of the second motor 2 in map2 The maximum output torque of the second motor 2;

The method for obtaining the maximum output torque of the third motor 3 includes: obtaining the third temperature of the third motor 3, the third voltage of the input terminal of the third motor 3, and the maximum supply current of the third motor 3, the maximum of the third motor 3 The power supply current, according to the third temperature, the third voltage, and the maximum power supply current of the third motor 3, query the correspondence between the third temperature, the third voltage, the third maximum power supply current and the maximum output torque of the third motor 3 in map3 The maximum output torque of the third motor 3.

S23: Sizes M11, M12 and M13.

If M11≤M12, execute S24; if M13≥M11>M12, execute S25; if M11>M13, execute S26.

S24: the first clutch 51 is disengaged, the second clutch 52 is disengaged, only the first motor 1 outputs torque, and the actual output torque of the first motor 1 is equal to M11.

M11≤M12, it means that only the first motor 1 can provide the output torque to meet the driving expectation of the driver, and the second motor 2 and the third motor 3 do not need to be used at this time.

S25: The first clutch 51 is engaged, the second clutch 52 is disengaged, the first motor 1 and the second motor 2 output torque simultaneously, and the sum of the actual output torque of the first motor 1 and the actual output torque of the second motor 2 is equal to M11.

M13≥M11>M12, indicating that the output torque provided by the first motor 1 cannot meet the driving expectations of the driver, at least the first motor 1 and the second motor 2 are required to provide output torque at the same time, so the vehicle controller 65 needs to control the first clutch 51 Engage and disengage the second clutch 52 so that the first motor 1 and the second motor 2 provide output torque at the same time, and the third motor 3 is not needed at this time.

S26: The first clutch 51 is engaged, the second clutch 52 is engaged, the first motor 1, the second motor 2 and the third motor 3 output torque at the same time, and the actual output torque of the first motor 1 and the actual output torque of the second motor 2 and the actual output torque of the third motor 3 is equal to M11.

M11>M13, indicating that only the first motor 1, the second motor 2 and the third motor 3 can provide output torque at the same time to meet the driver's expectations, so the vehicle controller 65 needs to control the first clutch 51 to engage and the second clutch 52 combination, the first motor 1, the second motor 2 and the third motor 3 provide output torque at the same time.

Brake torque distribution includes:

S31: Obtain the second required torque M21 for vehicle braking.

For example, the vehicle's second wheel end demand torque is calculated according to the rate of change of the accelerator pedal opening, vehicle speed and brake pedal opening.

S32: Obtain the maximum braking torque of the first motor 1, the second motor 2 and the third motor 3 respectively, and the maximum braking torque of the first motor 1 is M22; the maximum braking torque of the first motor 1 and the second motor The sum of the maximum braking torque of 2 is M23.

Wherein, obtaining the maximum braking torque of the first motor 1 includes: obtaining a first temperature of the first motor 1 , a first charging voltage at an output terminal of the first motor 1 , and a maximum charging current of the first motor 1 . According to the first temperature, the first charging voltage, the maximum charging current of the first motor 1 from the map11 between the first temperature, the first charging voltage, the maximum charging current of the first motor 1 and the maximum braking torque of the first motor 1 Query the corresponding maximum charging torque of the first motor 1 in .

Obtaining the maximum braking torque of the second electric machine 2 includes: obtaining a second temperature of the second electric machine 2 , a second charging voltage at the output terminal of the second electric machine 2 , and a maximum charging current of the second electric machine 2 . From the map21 between the second temperature, the second charging voltage, the maximum charging current of the second motor 2 and the maximum braking torque of the second motor 2 according to the second temperature, the second charging voltage, and the maximum charging current of the second motor 2 Query the corresponding maximum charging torque of the second motor 2 in .

Obtaining the maximum braking torque of the third motor 3 includes: obtaining a third temperature of the third motor 3 , a third charging voltage at an output terminal of the third motor 3 , and a maximum charging current of the third motor 3 . From the map31 between the third temperature, the third charging voltage, the maximum charging current of the third motor 3 and the maximum braking torque of the third motor 3 according to the third temperature, the third charging voltage, and the maximum charging current of the third motor 3 Query the corresponding maximum charging torque of the third motor 3 in .

S33: Compare the sizes of M21, M22 and M23.

If M21≤M22, execute S34; if M23≥M21>M22, execute S35; if M21>M23, execute S36.

S34: the first clutch 51 is disengaged, the second clutch 52 is disengaged, and only the first motor 1 is set to generate power to output braking torque.

M21≤M22, it means that only the first electric motor 1 can provide the braking torque to meet the driver's driving expectation, and the second electric motor 2 and the third electric motor 3 do not need to be used at this time.

S35: the first clutch 51 is engaged, the second clutch 52 is disengaged, and the first motor 1 and the second motor 2 are simultaneously set to generate power to output braking torque.

M23≥M21>M22, indicating that the braking torque provided by the first motor 1 cannot meet the driving expectation of the driver, at least the first motor 1 and the second motor 2 need to provide braking torque at the same time, so the vehicle controller 65 needs to control the first The clutch 51 is engaged and the second clutch 52 is disengaged, so that the first motor 1 and the second motor 2 provide braking torque at the same time, and the use of the third motor 3 is avoided under the premise of ensuring normal braking of the whole vehicle.

S36: The first clutch 51 is engaged, the second clutch 52 is engaged, and the first motor 1 , the second motor 2 and the third motor 3 are simultaneously set to generate power to output braking torque.

M21>M23, indicating that only the first motor 1, the second motor 2 and the third motor 3 can provide braking torque at the same time to meet the driver's expectations, so the vehicle controller 65 needs to control the first clutch 51 to engage and the second The clutch 52 is engaged, and the first motor 1 , the second motor 2 and the third motor 3 provide braking torque at the same time.

S37: Calculate the sum of the maximum braking torque of the first motor 1, the maximum braking torque of the second motor 2 and the maximum braking torque of the third motor 3 as M24.

S38: Compare the sizes of M21 and M24; if M21>M24; execute S39; if M21≤M24, execute S10.

S39: Start the hydraulic braking mechanism to brake the wheel ends.

M21>M24 means that even if the three motors provide braking torque at the same time, the driving expectation of the driver cannot be met, and the hydraulic braking mechanism is activated to brake the wheel ends.

In the power system control method of the four-wheel drive pure electric vehicle, when only the first motor 1 and the second motor 2 are put into use to meet the driving needs, the third motor 3 can be turned off, thereby reducing the use time of the third motor 3 , prolong the service life of the third motor 3, and at the same time avoid the waste of energy caused by the limitation of the energy conversion efficiency of the third motor 3, thereby prolonging the cruising range. When only the first motor 1 is put into use to meet the driving needs, the second motor 2 and the third motor 3 can be turned off, thereby reducing the service time of the second motor 2 and the third motor 3 and extending the duration of the second motor 2 and the third motor. The service life of the motor 3 can also be avoided, and the energy waste caused by the limitation of the energy conversion efficiency of the second motor 2 and the third motor 3 can be avoided at the same time, and the cruising range can be extended.

The present application provides a power system control method and a power system of a four-wheel drive pure electric vehicle. The power system control method of the four drive pure electric vehicle includes: when the current working condition is a driving working condition, executing drive torque distribution. Executing the driving torque distribution includes obtaining the first required torque M11 for driving the vehicle, respectively obtaining the maximum output torques of the first motor, the second motor and the third motor, and the maximum output torque of the first motor is M12, the first The sum of the maximum output torque of the motor and the maximum output torque of the second motor is M13, compare the sizes of M11, M12 and M13, and respond to the determination of M11≤M12, the first clutch is disengaged, the second clutch is disengaged, and the first motor outputs Torque, and the actual output torque of the first motor is equal to M11, avoiding the use of the second motor and the third motor, thereby reducing the energy waste caused by the second motor and the third motor’s own power conversion efficiency that cannot reach 100%, and extending the length of the vehicle In response to determining M13≥M11>M12, the first clutch is engaged, the second clutch is disengaged, the first motor and the second motor output torque at the same time, and the actual output torque of the first motor and the actual output torque of the second motor The sum is equal to M11, which can avoid the use of the third motor, thereby reducing the energy waste caused by the third motor’s own power conversion efficiency not reaching 100%, and extending the cruising range; in response to determining M11>M13, the first clutch is engaged, and the second clutch is engaged. The two clutches are combined, the first motor, the second motor and the third motor output torque simultaneously, and the sum of the actual output torque of the first motor, the actual output torque of the second motor and the actual output torque of the third motor is equal to M11.

Claims

A power system control method of a four-wheel drive pure electric vehicle, the power system of the vehicle includes a first motor, a second motor, a third motor, a power battery, a first clutch and a second clutch, the first motor is connected to a wheel end drive connected, the second motor is selectively connected to the wheel end through the first clutch, the third motor is selectively connected to the wheel end through the second clutch, and the power battery is set to power the first A motor, the second motor and the third motor supply power, and the first motor, the second motor and the third motor can respectively generate electricity and charge the power battery; the method includes:

Obtain the current working condition of the vehicle;

performing drive torque distribution in response to determining that the current operating condition is a driving condition in which an accelerator pedal of the vehicle is depressed;

The execution of drive torque distribution includes:

Acquiring a first required torque M11 for driving the vehicle;

Obtain the maximum output torque of the first motor, the second motor and the third motor respectively, and the maximum output torque of the first motor is M12, the maximum output torque of the first motor and the The sum of the maximum output torque of the two motors is M13;

Compare the size of M11, M12 and M13;

In response to determining M11≤M12, the first clutch is disengaged, the second clutch is disengaged, the first electric motor outputs torque, and the actual output torque of the first electric motor is equal to M11;

In response to determining M13≥M11>M12, the first clutch is engaged, the second clutch is disengaged, the first motor and the second motor output torque simultaneously, and the actual output torque of the first motor, the The sum of the actual output torques of the second motor is equal to M11;

In response to determining M11>M13, the first clutch is engaged, the second clutch is engaged, the first motor, the second motor and the third motor simultaneously output torque, and the actual The sum of the output torque, the actual output torque of the second motor and the actual output torque of the third motor is equal to M11.
The method according to claim 1, wherein said acquiring the first required torque M11 for driving the vehicle comprises:

calculating the required torque at the first wheel end of the vehicle according to the opening degree of the accelerator pedal, the vehicle speed and the rate of change of the opening degree of the accelerator pedal;

Calculate the maximum adhesion force of the plurality of wheels of the vehicle according to the road surface adhesion parameters and wheel pressure parameters, and calculate the second wheel end for driving the vehicle according to the maximum adhesion force and the number of wheels of the vehicle demand torque;

The smaller value of the first wheel-side required torque and the second wheel-side required torque is used as the first required torque.
The method according to claim 1, wherein,

The obtaining the maximum output torques of the first motor, the second motor and the third motor respectively includes:

Obtain the first temperature of the first motor, the first voltage of the input terminal of the first motor, and the maximum supply current of the first motor, according to the first temperature, the first voltage, the first The maximum power supply current of a motor is queried from the map1 between the first temperature, the first voltage, the first maximum power supply current and the maximum output torque of the first motor for the corresponding maximum output torque of the first motor;

Obtain the second temperature of the second motor, the second voltage of the input terminal of the second motor, and the maximum supply current of the second motor, according to the second temperature, the second voltage, the first The maximum power supply current of the second motor queries the corresponding maximum output torque of the second motor from the map2 between the second temperature, the second voltage, the second maximum power supply current and the maximum output torque of the second motor;

Obtain a third temperature of the third motor, a third voltage at the input terminal of the third motor, and a maximum supply current of the third motor, according to the third temperature, the third voltage, the first The maximum supply current of the three motors is searched for the corresponding maximum output torque of the third motor from map3 among the third temperature, the third voltage, the third maximum supply current and the maximum output torque of the third motor.
The method according to claim 1, further comprising:

performing braking torque distribution in response to determining that the current operating condition is a braking operating condition in which a brake pedal of the vehicle is depressed;

The braking torque distribution includes:

obtaining a second required torque M21 for braking the vehicle;

Obtain the maximum braking torque of the first motor, the second motor and the third motor respectively, and the maximum braking torque of the first motor is M22; the maximum braking torque of the first motor and The sum of the maximum braking torques of the second motor is M23;

Compare the size of M21, M22 and M23;

In response to determining M21≤M22, the first clutch is disengaged, the second clutch is disengaged, and the first electric machine is configured to generate power to output braking torque;

In response to determining M23≥M21>M22, the first clutch is engaged, the second clutch is disengaged, and the first motor and the second motor are simultaneously configured to generate power to output braking torque;

In response to determining M21>M23, the first clutch is engaged, the second clutch is engaged, and the first motor, the second motor, and the third motor are simultaneously configured to generate power to output braking torque.
The method according to claim 4, wherein, after said controlling the engagement of the first clutch and the engagement of the second clutch, further comprising:

calculating the sum of the maximum braking torque of the first motor, the maximum braking torque of the second motor and the maximum braking torque of the third motor as M24;

Compare the size of M21 and M24;

In response to determining M21>M24; activate the hydraulic braking mechanism to brake the wheel ends.
A power system of a four-wheel-drive pure electric vehicle, comprising a first motor, a second motor, a third motor, a power battery, a first clutch, a second clutch and a controller, the first motor is connected to the wheel end drive, and the The second motor is selectively connected to the wheel end through the first clutch, the third motor is selectively connected to the wheel end through the second clutch, and the power battery is configured to provide power to the first motor, The second motor and the third motor supply power, and the first motor, the second motor and the third motor can generate electricity and charge the power battery;

The controller is configured to implement the power system control method of the four-wheel drive pure electric vehicle described in any one of claims 1-5.
The system according to claim 6, wherein the power battery comprises at least one of a lithium-ion power battery, a flywheel energy storage battery system, and a fuel cell system.
The system according to claim 6, wherein the first electric motor is in transmission connection with the rear axle, the second electric motor is selectively in transmission connection with the rear axle through the first clutch, and the third electric motor is in transmission connection with the rear axle through the first clutch. Two clutches are selectively connected to the front axle transmission.
The system of claim 8, further comprising: a front retarder;

The second clutch is arranged between the third motor and the front reducer, and the front reducer is connected to the front axle in transmission; or,

The third motor is in transmission connection with the front reducer, and the second clutch is arranged between the front reducer and the front axle.
The system of claim 8, further comprising: a rear retarder;

The first motor is in transmission connection with the rear reducer, and the rear reducer is in transmission connection with the rear axle;

The second electric motor is selectively connected in transmission with the rear reducer through the first clutch.