Pure electric vehicle power system, pure electric vehicle and control method

文档序号:180739 发布日期:2021-11-02 浏览:32次 中文

阅读说明:本技术 纯电动汽车动力系统、纯电动汽车及控制方法 (Pure electric vehicle power system, pure electric vehicle and control method ) 是由 车显达 刘建康 王燕 刘力源 于 2021-09-09 设计创作,主要内容包括:本发明涉及车辆领域,公开了一种纯电动汽车动力系统、纯电动汽车及控制方法,本发明提供的纯电动汽车系统,第一电机和第二电机为轮毂电机,轮毂电机相比其他电机而言,轮毂电机进行电能回收的效率更高,更加有利于降低整车电能消耗;可以通过调节离合器的状态,实现两驱控制和四驱控制的切换;本发明提供的纯电动汽车控制方法,车辆行驶时,若离合器使第三电机与第二车轮连接,可以实现轮毂电机和集中式电机共同控制车辆行驶;若离合器使第三电机与第二车轮断开连接,可以实现轮毂电机单独控制车辆行驶,实现两驱控制和四驱控制的切换,便于根据实际需求选择两驱或四驱控制,以避免长期采用四驱控制时耗能损失较大的问题。(The invention relates to the field of vehicles and discloses a pure electric vehicle power system, a pure electric vehicle and a control method, wherein in the pure electric vehicle system provided by the invention, a first motor and a second motor are hub motors, and compared with other motors, the hub motors have higher efficiency of recovering electric energy and are more beneficial to reducing the electric energy consumption of the whole vehicle; the switching between the two-wheel drive control and the four-wheel drive control can be realized by adjusting the state of the clutch; according to the control method of the pure electric vehicle, when the vehicle runs, if the third motor is connected with the second wheel through the clutch, the hub motor and the centralized motor can jointly control the vehicle to run; if the clutch enables the third motor to be disconnected with the second wheel, the wheel hub motor can be independently controlled to drive the vehicle, the two-wheel drive control and the four-wheel drive control can be switched, the two-wheel drive control or the four-wheel drive control can be conveniently selected according to actual requirements, and the problem of large energy loss when the four-wheel drive control is adopted for a long time is solved.)

1. The pure electric vehicle comprises two first wheels and two second wheels, wherein one of the first wheels and the second wheels is a front wheel (41), and the other one of the first wheels and the second wheels is a rear wheel (42); the pure electric automobile power system is characterized by comprising:

a first motor (11), the output end of the first motor (11) is directly connected with one of the first wheels;

a second motor (21), the output end of the second motor (21) is directly connected with the other first wheel;

the output end of the third motor (31) is in transmission connection with the two second wheels through a transmission unit (34) and a main speed reducer (33), the third motor (31) is in transmission connection with the transmission unit (34) through a clutch (32), or the transmission unit (34) is in transmission connection with the main speed reducer (33) through the clutch (32), or the main speed reducer (33) is in transmission connection with the two second wheels through the clutch (32);

the first motor (11) and the second motor (21) are hub motors, and the third motor (31) is a centralized motor.

2. The pure electric vehicle powertrain according to claim 1, wherein the clutch (32) is a one-way clutch.

3. The pure electric vehicle powertrain according to claim 1, wherein the clutch (32) is a bi-directional clutch.

4. The pure electric vehicle powertrain according to claim 1, wherein the transmission unit (34) is a shift transmission.

5. A pure electric vehicle, characterized by comprising the pure electric vehicle power system of any one of claims 1 to 4.

6. The pure electric vehicle control method is applied to the pure electric vehicle in claim 5, and is characterized by comprising the following steps of:

when the vehicle is in a running state, calculating the running torque required by the running of the vehicle;

if the running torque is larger than the sum of maximum torques which can be generated from the first motor (11) and the second motor (21) to the wheel end, the first motor (11), the second motor (21) and the third motor (31) drive the vehicle to run together;

and if the running torque is not more than the sum of the maximum torques which can be generated from the first motor (11) and the second motor (21) to the wheel end, driving the vehicle to run by the first motor (11) and the second motor (21).

7. The pure electric vehicle control method according to claim 6,

when the vehicle is in a braking state, calculating the braking torque required by the braking of the vehicle;

if the braking torque is not larger than the sum of the maximum negative torques which can be generated from the first motor (11) and the second motor (21) to the wheel end, the first motor (11) and the second motor (21) provide negative torques to brake the vehicle.

8. The pure electric vehicle control method according to claim 7, characterized in that if the braking torque is larger than the sum of the maximum negative torques which can be generated from the first electric machine (11) and the second electric machine (21) to the wheel end and the clutch (32) is a one-way clutch, the braking of the vehicle is carried out by the negative torques provided by the first electric machine (11) and the second electric machine (21) and the torque provided by a hydraulic braking system of the vehicle.

9. The pure electric vehicle control method according to claim 7, characterized in that if the clutch (32) is a bidirectional clutch and the braking torque is larger than the sum of the maximum negative torques which can be generated from the first electric machine (11), the second electric machine (21) and the third electric machine (31) to the wheel end, the first electric machine (11), the second electric machine (21) and the third electric machine (31) provide negative torques and the hydraulic braking system provides torques to jointly brake the vehicle;

if the clutches (32) are all bidirectional clutches, the braking torque is not larger than the sum of the maximum negative torques which can be generated from the first motor (11), the second motor (21) and the third motor (31) to the wheel ends, and the braking torque is larger than the sum of the maximum negative torques which can be generated from the first motor (11) and the second motor (21) to the wheel ends, the first motor (11), the second motor (21) and the third motor (31) provide negative torques to brake the vehicle.

10. A pure electric vehicle control method according to claim 8 or 9, characterized in that when the vehicle is braked by the negative torque provided by the electric machine, the braking energy generated by the electric machine providing the negative torque is formed into electric energy to be stored in the power battery.

Technical Field

The invention relates to the field of vehicles, in particular to a pure electric vehicle power system, a pure electric vehicle and a control method.

Background

The traditional pure electric vehicle adopts the permanent magnet synchronous motor as power, the back-dragging torque of the permanent magnet synchronous motor under the follow-up working condition is larger, and in order to prevent the situation that the back electromotive force is too high, the weak magnetic current during high-speed running is larger, so that the consumed electric energy is larger, therefore, the power consumption of the four-wheel drive vehicle adopting the permanent magnet synchronous motor as power is higher, and the endurance mileage of the whole vehicle is shorter.

Disclosure of Invention

The invention aims to provide a pure electric vehicle power system, a pure electric vehicle and a control method, which can reduce the energy consumption of the whole vehicle and prolong the endurance mileage of the whole vehicle.

In order to achieve the purpose, the invention adopts the following technical scheme:

the pure electric vehicle comprises two first wheels and two second wheels, wherein one of the first wheels and the second wheels is a front wheel, and the other one of the first wheels and the second wheels is a rear wheel; pure electric vehicles driving system includes:

the output end of the first motor is directly connected with one of the first wheels;

the output end of the second motor is directly connected with the other first wheel;

the output end of the third motor is in transmission connection with the two second wheels through a transmission unit and a main speed reducer, the third motor is in transmission connection with the transmission unit through a clutch, or the transmission unit is in transmission connection with the main speed reducer through the clutch, or the main speed reducer is in transmission connection with the two second wheels through the clutch;

the first motor and the second motor are hub motors, and the third motor is a centralized motor.

As a preferable technical scheme of the pure electric vehicle power system, the clutch is a one-way clutch.

As a preferred technical scheme of the pure electric vehicle power system, the clutch is a bidirectional clutch.

As an optimal technical scheme of the pure electric vehicle power system, the transmission unit is a gear shifting transmission.

The invention also provides a pure electric vehicle which comprises the pure electric vehicle power system.

The invention also provides a control method of the pure electric vehicle, which is applied to the pure electric vehicle and comprises the following steps:

when the vehicle is in a running state, calculating the running torque required by the running of the vehicle;

if the running torque is larger than the sum of maximum torques which can be generated from the first motor and the second motor to a wheel end, the first motor, the second motor and the third motor drive the vehicle to run together;

and if the running torque is not greater than the sum of the maximum torques which can be generated from the first motor and the second motor to the wheel end, driving the vehicle to run by the first motor and the second motor.

As a preferable technical solution of the control method of the pure electric vehicle,

when the vehicle is in a braking state, calculating the braking torque required by the braking of the vehicle;

and if the braking torque is not larger than the sum of the maximum negative torques which can be generated from the first motor and the second motor to the wheel end, the first motor and the second motor provide negative torques to brake the vehicle.

As a preferable technical solution of the above-mentioned pure electric vehicle control method, if the braking torque is greater than the sum of maximum negative torques that can be generated from the first motor and the second motor to the wheel end and the clutch is a one-way clutch, the vehicle is braked by the negative torque provided by the first motor and the second motor and the torque provided by a hydraulic braking system of the vehicle.

As a preferred technical solution of the above pure electric vehicle control method, if the clutch is a bidirectional clutch and the braking torque is greater than the sum of maximum negative torques that can be generated from the first motor, the second motor and the third motor to the wheel end, the first motor, the second motor and the third motor provide negative torque and the hydraulic braking system provides torque to jointly brake the vehicle;

if the clutches are all bidirectional clutches, the braking torque is not larger than the sum of the maximum negative torques which can be generated from the first motor, the second motor and the third motor to the wheel ends, and the braking torque is larger than the sum of the maximum negative torques which can be generated from the first motor and the second motor to the wheel ends, the first motor, the second motor and the third motor provide negative torques to brake the vehicle.

As a preferred technical solution of the above-mentioned pure electric vehicle control method, when the vehicle is braked by the negative torque provided by the electric motor, the braking energy generated by the electric motor providing the negative torque is formed into electric energy to be stored in the power battery.

The invention has the beneficial effects that: according to the pure electric vehicle power system provided by the invention, the first motor and the second motor are hub motors, and the third motor is a centralized motor; when the vehicle runs, if the third motor is connected with the second wheel through the clutch, the hub motor and the centralized motor can jointly control the vehicle to run; if the clutch enables the third motor to be disconnected with the second wheel, the wheel hub motor can be independently controlled to drive the vehicle, the two-wheel drive control and the four-wheel drive control can be switched, the two-wheel drive control or the four-wheel drive control can be conveniently selected according to actual requirements, and the problem of large energy loss when the four-wheel drive control is adopted for a long time is solved. And the in-wheel motor compares other motors, and the in-wheel motor carries out the efficiency of electric energy recovery higher, is favorable to reducing whole car electric energy consumption more.

According to the pure electric vehicle and the control method thereof provided by the invention, the first motor, the second motor and the third motor are selectively controlled to drive the vehicle to run together or the first motor and the second motor are controlled to drive the vehicle to run together according to the running torque required by the vehicle to run.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the contents of the embodiments of the present invention and the drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a pure electric vehicle power system according to a first embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a pure electric vehicle power system according to another embodiment of the present invention;

FIG. 3 is a flowchart of vehicle driving control in a control method of a pure electric vehicle powertrain according to an embodiment of the present invention;

FIG. 4 is a graph showing a relationship between a vehicle speed and a running torque output from a third motor to a wheel end when the control system of the pure electric vehicle in the first embodiment is adopted;

FIG. 5 is a flowchart of vehicle braking control in a control method of a pure electric vehicle powertrain according to an embodiment of the present invention;

FIG. 6 is a graph showing a relationship between a vehicle speed and a braking torque output from a third motor to a wheel end when the control system of the pure electric vehicle according to the first embodiment of the present invention is adopted;

FIG. 7 is a flowchart related to vehicle braking control in a pure electric vehicle powertrain control method according to a second embodiment of the present invention;

FIG. 8 is a schematic structural diagram of a pure electric vehicle power system according to a third embodiment of the present invention;

FIG. 9 is a schematic structural diagram of a pure electric vehicle power system according to another embodiment of the present invention;

FIG. 10 is a schematic structural diagram of a pure electric vehicle power system according to a fourth embodiment of the present invention;

FIG. 11 is a schematic structural diagram of a pure electric vehicle power system according to another embodiment of the present invention;

FIG. 12 is a schematic structural diagram of a pure electric vehicle power system according to a fifth embodiment of the present invention;

FIG. 13 is a graph of vehicle speed versus travel torque output by the third motor to the wheel ends as provided in a fifth embodiment of the present invention;

FIG. 14 is a graph of vehicle speed versus braking torque output by the third electric machine to the wheel ends as provided in a fifth embodiment of the present invention;

FIG. 15 is a schematic structural diagram of a pure electric vehicle power system according to another embodiment of the present invention;

FIG. 16 is a schematic structural diagram of a pure electric vehicle power system according to a sixth embodiment of the present invention;

FIG. 17 is a schematic structural diagram of a pure electric vehicle power system according to another embodiment of the present invention;

FIG. 18 is a schematic structural diagram of a pure electric vehicle power system according to a seventh embodiment of the present invention;

fig. 19 is a schematic structural diagram of a pure electric vehicle power system according to another embodiment of the present invention.

In the figure:

11. a first motor;

21. a second motor;

31. a third motor; 32. a clutch; 33. a main reducer; 34. a transmission unit;

41. a front wheel; 42. a rear wheel.

Detailed Description

In order to make the technical problems solved, the technical solutions adopted and the technical effects achieved by the present invention clearer, the technical solutions of the present invention are further described below by way of specific embodiments with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some but not all of the elements associated with the present invention are shown in the drawings.

Example one

Fig. 1 is a schematic structural diagram of a pure electric vehicle power system provided in this embodiment, and as shown in fig. 1, this embodiment provides a pure electric vehicle power system and a pure electric vehicle, where the pure electric vehicle includes the above pure electric vehicle power system, two first wheels and two second wheels, one of the first wheels and the second wheels is a front wheel 41, and the other is a rear wheel 42, and in this embodiment, the first wheel is taken as the front wheel 41, and the second wheel is taken as the rear wheel 42 as an example. In other embodiments, as shown in fig. 2, a first wheel may be provided as the rear wheel 42 and a second wheel may be provided as the front wheel 41.

The pure electric vehicle power system provided by the embodiment comprises a first motor 11, a second motor 21 and a third motor 31, wherein the output end of the first motor 11 is directly connected with one first wheel; the output of the second motor 21 is directly connected to another first wheel; the output end of the third electric machine 31 is in transmission connection with two second wheels through a transmission unit 34 and a main speed reducer 33, and the third electric machine 31 is in transmission connection with the transmission unit 34 through a clutch 32.

The first motor 11 and the second motor 21 are hub motors, the third motor 31 is a centralized motor, and when the third motor 31 and the second wheel are in transmission connection through the clutch 32, the hub motor and the centralized motor jointly control the running or braking of the vehicle. When the third motor 31 and the second wheel are disconnected through the clutch 32, the driving of the vehicle is controlled by the wheel hub motor alone, and the braking is carried out by selectively matching with a hydraulic braking system of the vehicle.

The pure electric vehicle system provided by the embodiment can realize the switching between the two-wheel drive control and the four-wheel drive control, and is convenient for selecting the two-wheel drive or the four-wheel drive control according to the actual requirement so as to avoid the problem of large energy loss when the four-wheel drive control is adopted for a long time.

In this embodiment, the clutch 32 is a one-way clutch, and it should be noted that the one-way clutch has only one default state, and there is no separation or combination state, and it does not need to be controlled by a controller, and the one-way clutch can only transmit power from one direction to the other direction, and cannot transmit power in the reverse direction.

Examples are as follows: when the clutch 32 is a one-way clutch, the driving force of the third motor 31 can be transmitted to the transmission unit 34 through the clutch 32, and then the transmission unit 34 transmits the power to the final drive 33 and the second wheel, so as to drive the vehicle to run forwards, but cannot drive the vehicle to reverse; in addition, in the process of forward driving of the vehicle, when the vehicle decelerates under the braking condition, because of the unidirectional property of the transmission force of the one-way clutch, the third motor 31 cannot generate a resistance force which hinders the forward movement of the vehicle, and the third motor 31 cannot realize the braking energy recovery function, namely, when the clutch 32 adopts the one-way clutch, the third motor 31 cannot be controlled to generate electricity to generate a negative torque to brake the vehicle, and meanwhile, the feedback electric energy is stored in the power battery.

Further, the electric vehicle power system further comprises a Vehicle Control Unit (VCU), an ESP (electronic stability program), a first motor controller (MCU1), a second motor controller (MCU2), a third motor controller (MCU3), a power battery and a Battery Management System (BMS), wherein the ESP, the first motor controller (MCU1), the second motor controller (MCU2), the third motor controller (MCU3) and the BMS are electrically connected with the vehicle control unit.

The battery management system is electrically connected with the power battery, can detect the residual electric quantity (SOC) of the power battery, the temperature of the power battery, the charging and discharging power of the power battery, the fault state of the power battery and the like, and can transmit a detection signal to the vehicle control unit.

First motor controller and first motor 11 electric connection, first motor controller can detect torque, rotational speed, power, temperature and the fault state etc. of first motor 11 to can transmit detected signal to vehicle control unit. The second motor controller is electrically connected with the second motor 21, can detect the torque, the rotating speed, the power, the temperature, the fault state and the like of the second motor 21, and can transmit the detection signal to the vehicle control unit. The third motor controller is electrically connected with the third motor 31, and the third motor controller can detect the torque, the rotating speed, the power, the temperature, the fault state and the like of the third motor 31 and can transmit the detection signal to the vehicle control unit.

The vehicle control unit can send control commands of motor torque and motor speed to the first motor controller, the second motor controller and the third motor controller, and the first motor controller, the second motor controller and the third motor 31 can control the first motor 11, the second motor 21 and the third motor 31 to operate according to the control commands.

The embodiment also provides a control method of the pure electric vehicle, which is applied to the pure electric vehicle. The control method can be divided into a control method in the running state and a control method in the braking state based on the vehicle state, whether the vehicle is in the running state is judged firstly, if so, the control method in the running state is executed, and if not, the control method in the braking state is executed when the vehicle is in the braking state.

As shown in fig. 3, the control method in the driving state includes the steps of:

and S111, calculating the running torque required by the running of the vehicle.

When the vehicle runs, the vehicle control unit calculates the running torque T _ driver required by the wheel end according to the opening degree of an accelerator pedal, the state of a brake pedal and a vehicle speed signal, namely the running torque required by the vehicle running. The above-described method of calculating the driving torque required for driving the vehicle is prior art in the automotive industry and will not be described in detail herein.

And S112, judging whether the running torque is larger than the sum of the maximum torques which can be generated from the first motor 11, the second motor 21 to the wheel end, if so, executing S113, and if not, executing S114.

The method of the maximum torque that can be generated by the first electric machine 11 to the wheel end is as follows: the first motor controller reports the maximum available torque T1_ driver of the first motor 11 according to the state of the first motor 11maxThe maximum torque generated from the first electric machine 11 to the wheel end is T1_ drivermax

The second motor controller reports the maximum available torque T2_ driver of the second motor 21 according to the state of the second motor 21maxA second electric machine 2The maximum torque which can be generated from 1 to the wheel end is T2_ drivermax

Therefore, the sum of the maximum torques that can be generated by the first electric machine 11 and the second electric machine 21 to the wheel end is equal to T1_ drivermax+T2_drivermax

And S1113, driving the vehicle to run by the first motor 11, the second motor 21 and the third motor 31 together.

When the running torque is larger than the sum of the maximum torques which can be generated from the first motor 11 and the second motor 21 to the wheel ends, which indicates that the vehicle runs under a heavy load condition, such as the vehicle runs at a rapid acceleration, goes up a heavy slope, and overtakes at a high speed, etc., the power requirement for running the vehicle cannot be met by the first motor 11 and the second motor 21 alone, so the first motor 11, the second motor 21 and the third motor 31 drive the vehicle to run together.

Since the clutch 32 in the present embodiment is a one-way clutch, there is no need to control the clutch 32, and in this case, torque distribution is required for the first motor 11, the second motor 21, and the third motor 31, as follows.

The method of calculating the maximum torque that can be generated by the third motor 31 to the wheel end is as follows: the third motor controller reports the maximum available torque of the third motor 31 as T3_ driver according to the state of the third motor 31maxThe maximum torque that can be generated from the third motor 31 to the wheel end is T3_ drivermaxXi 11, i11 is the product of the speed ratio of the transmission unit 34 and the speed ratio of the final drive 33.

The sum of the running torques output to the wheel end by the first motor 11 and the second motor 21 is T1_ driver + T2_ driver, and the running torque output to the wheel end by the third motor 31 is T3_ driver; note that T1_ driver ≦ T1_ drivermax,T2_driver≤T2_drivermax,T3_driver≤T3_drivermax

The vehicle-mounted controller is characterized in that T1_ driver + T2_ driver is y2 multiplied by T _ driver, T3_ driver is y1 multiplied by T _ driver, y1+ y2 is 1, and y1 and y2 are determined according to the requirements and the optimal performance of the whole vehicle. Illustratively, T1_ driver ═ T2_ driver, y1 ═ y2 ═ 1/2. It should be noted that specific values of y1 and y2 are not limited to the above limitations, and T1_ driver and T2_ driver may not be equal.

And S114, driving the vehicle to run by the first motor 11 and the second motor 21.

When the running torque is not greater than the sum of the maximum torques which can be generated from the first motor 11 and the second motor 21 to the wheel end, which indicates that the vehicle runs under the low-load working condition at the moment, such as vehicle starting, smooth acceleration, high-speed stable running and the like, the power requirement of the vehicle running can be met by means of the first motor 11 and the second motor 21, so that the vehicle is driven by the first motor 11 and the second motor 21 to run.

Fig. 4 is a graph of the relationship between the vehicle speed and the running torque provided in the present embodiment, and referring to fig. 4, when the running torque is not greater than the sum of the maximum torques that can be generated from the first motor 11 and the second motor 21 to the wheel end, in the region a shown in fig. 4, the first motor 11 and the second motor 21 are controlled to output power according to the running torque, and the third motor 31 is in a stationary state and does not output torque.

When the running torque is not greater than the sum of the maximum torques that can be generated by the first electric machine 11 and the second electric machine 21 to the wheel end, the running torque is the torque output by the first electric machine 11 to the wheel end + the torque output by the second electric machine 21 to the wheel end, i.e., T2_ driver is T1_ driver + T2_ driver, and preferably T1_ driver is T2_ driver.

Because the third motor 31 does not work, and the first motor 11 and the second motor 21 are hub motors, the hub motors are adopted to drive the vehicle to run, and compared with the method that other motors are adopted to control the vehicle to run, the power consumption of the hub motors is low when the hub motors work; in addition, the two-drive control is adopted for driving, and compared with the four-drive control when the first motor 11, the second motor 21 and the third motor 31 all work, the power consumption of the two-drive control is smaller; moreover, the one-way clutch provided in the third motor 31 does not generate running resistance even if the third motor 31 does not operate, and the vehicle has a longer range.

As shown in fig. 5, the control method in the braking state includes the steps of:

and S121, calculating the braking torque required by vehicle braking.

The vehicle control unit calculates the braking torque T _ brake required by the wheel end according to the pressure of the brake master cylinder of the driver, the state of the accelerator pedal and the like, namely the braking torque required by the vehicle braking. The above-described method of calculating the braking torque required for braking the vehicle is prior art in the automotive industry and will not be described in detail herein.

And S122, judging whether the braking torque is larger than the sum of the maximum negative torques which can be generated from the first motor 11 and the second motor 21 to the wheel end, if so, executing S123, and if not, executing S124.

The maximum allowable braking torque of the first electric machine 11 itself is T1_ brakemaxThe maximum negative torque generated from the first motor 11 to the wheel end is T1_ brakemax

The maximum allowable braking torque of the second electric machine 21 is T2_ brakemaxThe maximum negative torque generated from the second motor 21 to the wheel end is T2_ brakemax

The sum of the maximum negative torques that can be generated by the first motor 11 and the second motor 21 to the wheel end is equal to T1_ brakemax+T2_brakemax

And S123, braking the vehicle by jointly providing the negative torque by the first motor 11 and the second motor 21 and providing the torque by a hydraulic braking system of the vehicle.

When the braking torque is greater than the sum of the maximum negative torques which can be generated from the first motor 11 and the second motor 21 to the wheel end, it is indicated that emergency braking is performed at this time, the driver steps on the brake pedal again, the demand of the braking torque is large, and the braking by the negative torques provided by the first motor 11 and the second motor 21 cannot meet the demand of the braking torque.

When the braking torque is larger than the sum of the maximum negative torques which can be generated by the first motor 11 and the second motor 21 to the wheel end, the sum of the negative torques generated by the first motor 11 and the second motor 21 to the wheel end is T1_ brakemax+T2_brakemaxTorque meter for braking provided by a hydraulic braking systemIs T _ break'.

T_brake’=T_brake-T1_brakemax-T2_brakemaxTherefore, the maximum braking energy generated by the first motor 11 and the second motor 21 is convenient to form electric energy to be stored in the power battery, and energy recycling is realized.

And S124, providing negative torque by the first motor 11 and the second motor 21 to brake the vehicle.

When the braking torque is not greater than the sum of the maximum negative torques which can be generated from the first motor 11 and the second motor 21 to the wheel end, it is indicated that the braking torque requirement can be met already when the first motor 11 and the second motor 21 provide the negative torques for braking, the vehicle control unit sends a control instruction to the first motor controller, the second motor controller and the third motor controller according to the braking torque, the first motor 11 and the second motor 21 provide the negative torques for braking the vehicle, the third motor 31 does not work at rest, neither the braking torque is output nor the electric energy is recovered, the electric energy is not consumed at the same time, the vehicle resistance is smaller when the vehicle is driven by the hub motor to run, the power consumption of the whole vehicle is small, and the mileage of the vehicle is longer.

When the braking torque is not greater than the sum of the maximum negative torques which can be generated by the first electric machine 11 and the second electric machine 21 to the wheel end, the braking torque is equal to the negative torque which is output by the first electric machine 11 to the wheel end and the negative torque which is output by the second electric machine 21 to the wheel end, i.e., T _ brake is T1_ brake + T2_ brake, and preferably T1_ brake is T2_ brake.

Fig. 6 is a graph of the relationship between the vehicle speed and the braking torque provided in the present embodiment, and referring to fig. 6, when the braking torque is not greater than the sum of the maximum negative torques that can be generated from the first motor 11 and the second motor 21 to the wheel end, in the region a1 shown in fig. 6, the first motor 11 and the second motor 21 are controlled to output power according to the braking torque. Because first motor 11 and second motor 21 are wheel hub motor, wheel hub motor compares other motors, and wheel hub motor carries out the efficiency that electric energy was retrieved higher, is favorable to reducing whole car electric energy consumption more.

Example two

The difference between the present embodiment and the first embodiment is that the clutch 32 adopts a bidirectional clutch, and the pure electric vehicle power system provided in the present embodiment further includes a clutch controller, the clutch controller is electrically connected with a vehicle control unit (TCU), the clutch controller is electrically connected with the clutch 32, and the clutch controller can detect a state of the clutch 32 and transmit a detection signal to the vehicle control unit; the vehicle control unit is capable of adjusting the state of the clutch 32 via the clutch control.

It should be noted that the bidirectional clutch has three states, namely a separation state, a combination state and a slip state, and the state of the bidirectional clutch can be adjusted by sending a control command to the clutch controller through the vehicle controller. When the bidirectional clutch is in a separation state, parts at two ends of the bidirectional clutch cannot transmit power; when the bidirectional clutch is in a combined state, the parts at the two ends of the bidirectional clutch can normally transmit power; when the two-way clutch is in a slip state, the two-way clutch can transmit a part of power. The following is illustrated in connection with fig. 1: when the clutch 32 is in the engaged state, the third motor 31 can transmit the driving force to the rear wheel 42 to drive the vehicle to run; in the braking process of the vehicle, the third motor 31 can also be controlled to generate power, generate negative torque to brake the vehicle, and simultaneously recover braking energy. When the clutch 32 is in the disengaged state, the third motor 31 cannot drive the vehicle, and the braking energy cannot be recovered, and the third motor 31 also cannot generate a resistance to the vehicle.

Since the present embodiment uses a different type of clutch 32 than the first embodiment, the control method of the pure electric vehicle powertrain is different. Based on the pure electric vehicle power system provided by this embodiment, a detailed description is given below of a control method of a power vehicle using the pure electric vehicle power system.

The control method under the driving state comprises the following steps:

and S211, calculating the running torque required by the running of the vehicle.

When the vehicle runs, the vehicle control unit calculates the running torque T _ driver required by the wheel end according to the opening degree of an accelerator pedal, the state of a brake pedal and a vehicle speed signal, namely the running torque required by the vehicle running. The above-described method of calculating the driving torque required for driving the vehicle is prior art in the automotive industry and will not be described in detail herein.

S212, judging whether the running torque is larger than the sum of the maximum torques which can be generated from the first motor 11, the second motor 21 to the wheel end, if so, executing S213, and if not, executing S214.

The first motor controller reports the maximum available torque T1_ driver of the first motor 11 according to the state of the first motor 11maxThe maximum torque generated from the first electric machine 11 to the wheel end is T1_ drivermax

The second motor controller reports the maximum available torque T2_ driver of the second motor 21 according to the state of the second motor 21maxThe maximum torque that can be generated from the second electric machine 21 to the wheel end is T2_ drivermax

Therefore, the sum of the maximum torques that can be generated by the first electric machine 11 and the second electric machine 21 to the wheel end is equal to T1_ drivermax+T2_drivermax

And S213, driving the vehicle to run by the first motor 11, the second motor 21 and the third motor 31 together.

When the running torque is larger than the sum of the maximum torques which can be generated from the first electric machine 11 and the second electric machine 21 to the wheel end, it is described that the power requirement for running the vehicle cannot be met by means of the first electric machine 11 and the second electric machine 21.

Since the clutch 32 in this embodiment is a bidirectional clutch, when the running torque is greater than the sum of the maximum torques that can be generated from the first motor 11 and the second motor 21 to the wheel end, the vehicle controller sends a command to the clutch controller to switch the clutch 32 to the engaged state, so as to realize that the vehicle is driven by the first motor 11, the second motor 21 and the third motor 31 together. In this case, torque distribution is required for the first motor 11, the second motor 21, and the third motor 31, and the specific method is as follows.

The method of the maximum torque that can be generated by the third electric machine 31 to the wheel end is as follows: the third motor controller reports the maximum available torque T3 — driver of the third motor 31 depending on the state of the third motor 31maxThe maximum torque generated from the third motor 31 to the wheel end is T3_ drivermaxXi 11, i11 is the product of the speed ratio of the transmission unit 34 and the speed ratio of the final drive 33.

The sum of the running torques output to the wheel end by the first motor 11 and the second motor 21 is T1_ driver + T2_ driver, and the running torque output to the wheel end by the third motor 31 is T3_ driver. Note that T1_ driver ≦ T1_ drivermax,T2_driver≤T2_drivermax,T3_driver≤T3_drivermax×i11。

T3_ driver is y1 × T _ driver, T1_ driver + T2_ driver is y2 × T _ driver, y1+ y2 is 1, and y1 and y2 are determined according to the vehicle requirements and the optimal performance. Illustratively, T1_ driver ═ T2_ driver, y1 ═ y2 ═ 1/2. It should be noted that specific values of y1 and y2 are not limited to the above limitations, and T1_ driver and T2_ driver may not be equal.

And S214, driving the vehicle to run by the first motor 11 and the second motor 21.

When the running torque is not greater than the sum of the maximum torques which can be generated by driving the first motor 11 and the second motor 21 to the wheel end, which indicates that the power requirement of the vehicle running can be met by means of driving the first motor 11 and the second motor 21, the vehicle control unit sends control commands to the clutch controller, the first motor controller, the second motor controller and the third motor controller according to the running torque so as to switch the clutch 32 to the separation state, the third motor 31 is static and does not work, and the vehicle is driven by the first motor 11 and the second motor 21 to run. Referring to fig. 4 in the first embodiment, when the running torque is not greater than the sum of the maximum torques that can be generated from the first electric machine 11 and the second electric machine 21 to the wheel end, in the region a shown in fig. 4, the first electric machine 11 and the second electric machine 21 are controlled to output power according to the running torque, and the third electric machine 31 is in a stationary state and does not output torque.

When the running torque is not greater than the sum of the maximum torques that can be generated by the first electric machine 11 and the second electric machine 21 to the wheel end, the running torque is the torque output by the first electric machine 11 to the wheel end + the torque output by the second electric machine 21 to the wheel end, i.e., T2_ driver is T1_ driver + T2_ driver, and preferably T1_ driver is T2_ driver.

Because the third motor 31 does not work, and the first motor 11 and the second motor 21 are hub motors, the hub motors are adopted to drive the vehicle to run, and compared with the method that other motors are adopted to control the vehicle to run, the power consumption of the hub motors is low when the hub motors work; in addition, the two-drive control mode is adopted for running, and compared with the four-drive control mode when the first motor 11, the second motor 21 and the third motor 31 are all operated, the power consumption of the two-drive control mode is smaller.

As shown in fig. 7, the control method in the braking state includes the steps of:

and S221, calculating the braking torque required by the vehicle braking.

The vehicle control unit calculates the braking torque T _ brake required by the wheel end according to the pressure of the brake master cylinder of the driver, the state of the accelerator pedal and the like, namely the braking torque required by the vehicle braking. The above-described method of calculating the braking torque required for braking the vehicle is prior art in the automotive industry and will not be described in detail herein.

S222, judging whether the braking torque is larger than the sum of the maximum negative torques which can be generated from the first motor 11, the second motor 21 and the third motor 31 to the wheel end, if so, executing S223, and if not, executing S224.

The maximum allowable braking torque of the first electric machine 11 itself is T1_ brakemaxThe maximum negative torque generated from the first motor 11 to the wheel end is T1_ brakemax. The maximum allowable braking torque of the second motor 21 is T2_ brakemaxThe maximum negative torque generated from the second motor 21 to the wheel end is T2_ brakemax. The maximum allowable braking torque of the third motor 31 itself is T3_ brakemaxThe maximum negative torque generated from the third motor 31 to the wheel end is T3_ brakemaxXi 11, i11 is the product of the speed ratio of the transmission unit 34 and the speed ratio of the final drive 33.

The sum of the maximum negative torques which can be generated from the first motor 11, the second motor 21 and the third motor 31 to the wheel end is equal to T1_ brakemax+T2_brakemax+T3_brakemax×i1。

And S223, braking the vehicle by jointly providing the negative torque by the first motor 11, the second motor 21 and the third motor 31 and providing the torque by a hydraulic braking system of the vehicle.

When the braking torque is larger than the sum of the maximum negative torques which can be generated from the first motor 11, the second motor 21 and the third motor 31 to the wheel end, the emergency braking is performed, and the driver re-steps on the brake pedal, so that the braking torque is greatly required. Although the clutch 32 in this embodiment is a two-way clutch to enable the third electric machine 31 to provide negative torque, the braking torque demand cannot be met by the first electric machine 11, the second electric machine 21 and the third electric machine 31 providing negative torque together for braking, and therefore the vehicle is braked by the negative torque provided by the first electric machine 11, the second electric machine 21 and the third electric machine 31 and the torque provided by the hydraulic braking system of the vehicle together.

When the braking torque is larger than the sum of the maximum negative torques which can be generated from the first motor 11, the second motor 21 and the third motor 31 to the wheel end, the vehicle controller sends a control command to the clutch controller, the first motor controller, the second motor controller and the third motor controller according to the braking torque, so that the first motor 11, the second motor 21 and the third motor 31 all generate the negative torques.

The negative torque output by the first motor 11 to the wheel end is T1_ brakemaxThe negative torque output from the second motor 21 to the wheel end is T2_ brakemaxThe negative torque output from the third motor 31 to the wheel end is T3_ brakemaxAnd xi 11, the torque provided by the hydraulic brake system for braking is T _ brake'.

T_brake’=T_brake-T1_brakemax-T2_brakemax-T3_brakemaxThe multiplied by i31 is used for enabling the first motor 11, the second motor 21 and the third motor 31 to generate the maximum braking energy, so that the braking energy generated by the first motor 11, the second motor 21 and the third motor 31 is formed into electric energy to be stored in a power battery, energy recycling is realized, most of the energy can be recycled, and the electric energy consumption of the whole system is reduced.

And S224, judging whether the braking torque is larger than the sum of the maximum negative torques which can be generated from the first motor 11, the second motor 21 to the wheel end, if so, executing S225, and if not, executing S226.

And S225, the first motor 11, the second motor 21 and the third motor 31 provide negative torque to brake the vehicle.

When the braking torque is not greater than the sum of the maximum negative torques which can be generated from the first motor 11, the second motor 21 and the third motor 31 to the wheel end, and the braking torque is greater than the sum of the maximum negative torques which can be generated from the first motor 11, the second motor 21 and the third motor 31 to the wheel end, it is described that when the driver steps on the brake pedal at this time, the braking demand is relatively large, the braking torque demand cannot be met by depending on the negative torques provided by the first motor 11 and the second motor 21, because the clutch 32 is a bidirectional clutch, the first motor 11 and the second motor 21 can provide the negative torques, and the braking torque demand can be met by depending on the negative torques provided by the first motor 11, the second motor 21 and the third motor 31 together.

When the braking torque is not greater than the sum of the maximum negative torques which can be generated from the first motor 11, the second motor 21 and the third motor 31 to the wheel end, and the braking torque is greater than the sum of the maximum negative torques which can be generated from the first motor 11 and the second motor 21 to the wheel end, the vehicle control unit sends a control command to the clutch controller, the first motor controller, the second motor controller and the third motor controller according to the braking torque, so that the clutch 32 is combined, the first motor 11, the second motor 21 and the third motor 31 all generate negative torques to brake the vehicle, and simultaneously the braking energy generated by the first motor 11, the second motor 21 and the third motor 31 forms electric energy to be stored in the power battery, thereby realizing energy recycling and reducing the electric energy consumption of the whole system.

The sum of the braking torques output to the wheel ends by the first motor 11 and the second motor 21 is T1_ brake + T2_ brake, and the braking torque output to the wheel ends by the third motor 31 is T3_ brake.

Wherein, T1_ brake + T2_ brake ═ x2 × T _ brake, T3_ brake ═ x1 × T _ brake, x1+ x2 ═ 1, and x1 and x2 are determined according to the braking performance of the hub motor and the centralized motor. Illustratively, x1 ═ x2 ═ 1/2, and T1_ break ═ T2_ break. It should be noted that specific values of x1 and x2 are not limited to the above limitations, and T1_ break and T2_ break may not be equal.

And S226, providing negative torque by the first motor 11 and the second motor 21 to brake the vehicle.

When the braking torque is not greater than the sum of the maximum negative torques which can be generated from the first electric machine 11 and the second electric machine 21 to the wheel end, it is indicated that the braking torque requirement can be met already by the braking by the negative torques provided by the first electric machine 11 and the second electric machine 21, so the vehicle can be braked by the negative torques provided by the first electric machine 11 and the second electric machine 21. Although the clutch 32 is a bidirectional clutch to enable the third motor 31 to provide braking torque, the hub motor has higher electric energy recovery efficiency than a centralized motor, and is more beneficial to reducing the electric energy consumption of the whole vehicle, so that the third motor 31 is selected to provide negative torque to brake the vehicle under the condition.

When the braking torque is not larger than the maximum negative torque which can be generated from the first motor 11 and the second motor 21 to the wheel end, the vehicle controller sends a control command to the clutch controller, the first motor controller, the second motor controller and the third motor controller according to the braking torque, so that the clutch 32 is switched to a separation state, the third motor 31 is static and does not work, and the first motor 11 and the second motor 21 generate the negative torque. Referring to fig. 6 in the first embodiment, when the braking torque is not greater than the sum of the maximum negative torques that can be generated by the first electric machine 11 and the second electric machine 21 to the wheel end, in the region a1 shown in fig. 6, the first electric machine 11 and the second electric machine 21 are controlled to output power according to the braking torque, and the third electric machine 31 is in a stationary state and does not output torque.

When the braking torque is not greater than the sum of the maximum negative torques which can be generated by the first electric machine 11 and the second electric machine 21 to the wheel end, the braking torque is equal to the negative torque which is output by the first electric machine 11 to the wheel end and the negative torque which is output by the second electric machine 21 to the wheel end, i.e., T _ brake is T1_ brake + T2_ brake, and preferably T1_ brake is T2_ brake.

Because first motor 11 and second motor 21 are wheel hub motors, and third motor 31 is centralized motor, and wheel hub motor compares centralized motor, and wheel hub motor carries out the efficiency that electric energy was retrieved higher, is favorable to reducing whole car electric energy consumption more.

EXAMPLE III

The present embodiment differs from the first embodiment in that a clutch 32 is provided between a transmission unit 34 and a final drive 33, as shown in fig. 8.

The pure electric vehicle control method provided by the embodiment is respectively referred to as embodiment one and embodiment two according to the type of the clutch 32, and the description is not repeated here.

In other embodiments, as shown in fig. 9, the first wheel may be the rear wheel 42, and the second wheel may be the front wheel 41.

Example four

The present embodiment differs from the first embodiment in that a clutch 32 is provided between a final drive 33 and two second wheels, as shown in fig. 10.

The pure electric vehicle control method provided by the embodiment is respectively referred to as embodiment one and embodiment two according to the type of the clutch 32, and the description is not repeated here.

In other embodiments, as shown in fig. 11, the first wheel may be the rear wheel 42, and the second wheel may be the front wheel 41.

EXAMPLE five

As shown in fig. 12, the present embodiment further defines the transmission unit 34 as a shift transmission on the basis of the second embodiment, and the shift transmission is exemplified as a two-speed transmission in the present embodiment.

In order to realize automatic gear shifting, the pure electric vehicle power system further comprises a gear shifting controller, the gear shifting controller is electrically connected with the vehicle control unit, and the gear shifting controller can send a control instruction to the double-gear transmission so as to enable a gear shifting executing mechanism of the double-gear transmission to take off or engage. In the pure electric vehicle control method adopting the pure electric vehicle control system provided by the embodiment, reference is made to the first embodiment and the second embodiment according to the type of the clutch 32, and the description is not repeated here.

When the two-gear transmission is in the first gear, the product of the speed ratio of the two-gear transmission and the speed ratio of the main reducer 33 is recorded as a first-gear speed ratio i11, and the corresponding maximum vehicle speed is V11; when the two-gear transmission is in the second gear, the product of the speed ratio of the two-gear transmission and the speed ratio of the final drive 33 is recorded as a second-gear speed ratio i12, and the corresponding maximum vehicle speed is V12.

Fig. 13 is a graph showing the relationship between the vehicle speed and the running torque output from the third motor to the wheel end, which is provided by the present embodiment, and the shift strategy is as follows: if the vehicle is in a running state and the vehicle speed and the running torque distributed to the third motor 31 are both in the region B in fig. 13, the transmission is preferably in the second gear; if the vehicle speed and the running torque distributed to the third motor 31 are in the region C in fig. 13, the transmission is preferably in first gear. If the vehicle speed and the running torque distributed to the third motor 31 are in the region a in fig. 13, the motor rotation speed N1 corresponding to the first gear operation of the transmission is calculated according to the vehicle speed and the first gear ratio, the motor rotation speed N2 corresponding to the second gear operation of the transmission is calculated according to the vehicle speed and the second gear ratio, the torque T1 corresponding to N1 and the torque T2 corresponding to N2 are calculated according to the motor efficiency map, if T1 is greater than T2, the transmission is preferably the first gear, and if T1 is less than T2, the transmission is preferably the second gear. It should be noted that the motor efficiency map refers to a graph of a relationship between a motor rotation speed and a motor torque, which is a prior art and will not be described in detail herein.

When the first gear is shifted to the second gear, the clutch 32 is adjusted to be in a separated state, the gear shifting actuating mechanism is controlled to be disengaged, the rotating speed of the third motor 31 is adjusted to be at the target rotating speed of the second gear, the gear shifting actuating mechanism is controlled to be engaged, and then the clutch 32 is adjusted to be in a combined state, so that the gear shifting transmission is switched to be in the second gear. And the second gear target rotating speed is equal to the rotating speed of the motor before gear shifting multiplied by a second gear speed ratio/first gear speed ratio.

When the second gear is shifted down to the first gear, the clutch 32 is adjusted to be in a separated state, the gear shifting actuating mechanism is controlled to be disengaged, the rotating speed of the third motor 31 is adjusted to be the target rotating speed of the first gear, the gear shifting actuating mechanism is controlled to be engaged, and then the clutch 32 is adjusted to be in a combined state, so that the gear shifting transmission is switched to the first gear. The first gear target rotating speed is equal to the rotating speed of the motor before gear shifting multiplied by the first gear speed ratio/the second gear speed ratio.

The control method for shifting by adopting the gear shifting control strategy when the pure electric vehicle runs is as follows:

s51, acquiring the vehicle speed;

s52, determining a target gear according to the vehicle speed;

the method for acquiring the target gear is detailed in the gear shifting strategy.

And S53, switching the gear shifting transmission to the target gear.

It should be noted that the shift control strategy provided in the present embodiment is only applicable to a pure electric vehicle in which the clutch 32 is disposed between the third electric machine 31 and the shift transmission, and the clutch 32 is a bidirectional clutch.

Fig. 14 is a graph of the relationship between the vehicle speed and the braking torque output from the third motor to the wheel end provided by the present embodiment, which provides the following gear shift strategy: if the vehicle is in a braking state and the vehicle speed and the braking torque distributed to the third electric machine 31 are both in the region B in fig. 13, the transmission is preferably in the second gear; if the vehicle speed and the braking torque distributed to the third motor 31 are in the region C in fig. 13, the transmission is preferably in first gear. If the vehicle speed and the braking torque distributed to the third motor 31 are in the region a in fig. 13, the motor speed N1 corresponding to the first gear operation of the transmission is calculated according to the vehicle speed and the first gear ratio, the motor speed N2 corresponding to the second gear operation of the transmission is calculated according to the vehicle speed and the second gear ratio, the torque T1 corresponding to N1 and the torque T2 corresponding to N2 are calculated according to the motor efficiency map, if T1 is greater than T2, the transmission is preferably the first gear, and if T1 is less than T2, the transmission is preferably the second gear.

In other embodiments, as shown in fig. 15, a first wheel may be provided as the rear wheel 42, and a second wheel may be provided as the front wheel 41.

EXAMPLE six

The present embodiment is different from the fifth embodiment in that a clutch 32 is provided between a transmission unit 34 and a final drive 33, as shown in fig. 16.

The pure electric vehicle control method provided by the embodiment is respectively referred to as embodiment five according to the type of the clutch 32, and the description is not repeated here.

In other embodiments, as shown in fig. 17, the first wheel may be the rear wheel 42, and the second wheel may be the front wheel 41.

EXAMPLE seven

The present embodiment is different from the fifth embodiment in that a clutch 32 is provided between a final drive 33 and two second wheels, as shown in fig. 18.

The pure electric vehicle control method provided by the embodiment is respectively referred to as embodiment five according to the type of the clutch 32, and the description is not repeated here.

In other embodiments, as shown in fig. 19, the first wheel may be the rear wheel 42, and the second wheel may be the front wheel 41.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Wherein the terms "first position" and "second position" are two different positions.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

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