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CN110126643B - Control method and system for distributed drive electric vehicle in the state of motor failure - Google Patents

Control method and system for distributed drive electric vehicle in the state of motor failure Download PDF

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CN110126643B
CN110126643B CN201910342111.3A CN201910342111A CN110126643B CN 110126643 B CN110126643 B CN 110126643B CN 201910342111 A CN201910342111 A CN 201910342111A CN 110126643 B CN110126643 B CN 110126643B
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motor
vehicle
failure
driving
torque
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CN110126643A (en
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张雷
王震坡
余文
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Beijing Institute Of Technology New Source Information Technology Co ltd
Beijing Institute of Technology BIT
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Beijing Institute Of Technology New Source Information Technology Co ltd
Beijing Institute of Technology BIT
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/32—Control or regulation of multiple-unit electrically-propelled vehicles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/32—Control or regulation of multiple-unit electrically-propelled vehicles
    • B60L15/38—Control or regulation of multiple-unit electrically-propelled vehicles with automatic control
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

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  • Transportation (AREA)
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Abstract

本发明公开一种电机失效状态下分布式驱动电动汽车的控制方法及系统。该控制方法包括：获取分布式驱动电动汽车的驱动电机失效情况；当驱动电机失效情况为不可控失效时，确定所有驱动电机的转矩信号均为零；当驱动电机失效情况为单电机失效或异侧双电机失效时，获取分布式驱动电动汽车的车辆参数；车辆参数包括车辆方向盘转角、车速和车辆实际横摆角速度；根据驱动电机失效情况和车辆参数，确定各个驱动电机的转矩信号；根据各个驱动电机的转矩信号调节分布式驱动电动汽车各个驱动电机的转矩。本发明可以实现电机失效状态下对四轮毂电机分布式驱动电动汽车进行控制，保证车辆的稳定性，同时不影响驾驶员驾驶。

Figure 201910342111

The invention discloses a control method and system for distributed driving of electric vehicles in the state of motor failure. The control method includes: acquiring the drive motor failure situation of the distributed drive electric vehicle; when the drive motor failure situation is an uncontrollable failure, determining that the torque signals of all drive motors are zero; when the drive motor failure situation is a single motor failure or When the two motors on different sides fail, the vehicle parameters of the distributed drive electric vehicle are obtained; the vehicle parameters include the steering wheel angle of the vehicle, the vehicle speed and the actual yaw rate of the vehicle; the torque signal of each drive motor is determined according to the failure situation of the drive motor and the vehicle parameters; The torque of each drive motor of the distributed drive electric vehicle is adjusted according to the torque signal of each drive motor. The invention can realize the control of the distributed drive electric vehicle of the four-wheel motor in the state of motor failure, so as to ensure the stability of the vehicle without affecting the driving of the driver.

Figure 201910342111

Description

Control method and system for distributed driving electric automobile in motor failure state
Technical Field
The invention relates to the field of vehicle control, in particular to a control method and a control system for a distributed driving electric vehicle in a motor failure state.
Background
The distributed driving electric automobile is characterized in that two or more driving motors are arranged on a vehicle, and each driving motor transmits power to a corresponding driving wheel through a certain path. Therefore, the distributed drive electric automobile mainly comprises two configurations: a dual motor drive configuration and a four motor drive configuration, while the drive motor failure referred to in this application is primarily directed to a four hub/wheel edge motor drive configuration.
When the driving motor fails, the motor torque is redistributed by a corresponding torque reconstruction method, so that the dynamic property and the yaw stability of the vehicle are ensured. The most approximate control method at present is dual-motor driving distributed driving vehicle limping control, which performs constant power limitation on a failed motor and enables a vehicle to run at a constant speed when the motor fails, and detects self state parameters by a sensor and adjusts the front wheel steering angle of the vehicle by a steering power-assisted system when the vehicle turns. The scheme mainly aims at a double-motor distributed driving scheme, if the method is used for controlling the four-hub-motor distributed driving electric automobile, the dynamic performance of the automobile is greatly limited, and the driving feeling of a driver is deviated from the usual driving habit due to the intervention of a power steering motor during steering, so that the driving is influenced. Therefore, the method is not suitable for the four-hub/wheel-edge motor-driven distributed driving electric vehicle, and the prior art has no fault-tolerant control method aiming at the failure state of the driving motor of the four-hub/wheel-edge motor-driven electric vehicle.
Disclosure of Invention
The invention aims to provide a control method and a control system for a distributed drive electric automobile in a motor failure state, so as to control the distributed drive electric automobile with four hub motors in the motor failure state, ensure the stability of the automobile and simultaneously not influence the driving of a driver.
In order to achieve the purpose, the invention provides the following scheme:
a control method for a distributed driving electric automobile in a motor failure state comprises the following steps:
acquiring the failure condition of a driving motor of the distributed driving electric automobile; the drive motor failure condition includes: single motor failure, double motor failure on different sides and uncontrollable failure; the uncontrollable failures comprise two-motor failures, three-motor failures and four-motor failures on the same side;
when the failure condition of the driving motors of the distributed driving electric automobile is uncontrollable failure, determining that the torque signals of all the driving motors are zero;
when the failure condition of the driving motor of the distributed driving electric automobile is single motor failure or double motors on different sides are failed, vehicle parameters of the distributed driving electric automobile are obtained; the vehicle parameters comprise a vehicle steering wheel angle, a vehicle speed and a vehicle actual yaw rate;
determining torque signals of all driving motors according to the failure conditions of the driving motors of the distributed driving electric automobile and the vehicle parameters;
and adjusting the torque of each driving motor of the distributed driving electric automobile according to the torque signal of each driving motor.
Optionally, the obtaining of the failure condition of the driving motor of the distributed driving electric vehicle further includes:
acquiring a motor failure factor of each motor controller;
determining the failure condition of each driving motor of the distributed driving electric automobile according to the value of the motor failure factor; when the value of the motor failure factor is 1, determining that the corresponding driving motor has no failure; and when the value of the motor failure factor is 0, determining that the corresponding driving motor fails.
Optionally, determining a torque signal of each driving motor according to the failure condition of the driving motor of the distributed driving electric vehicle and the vehicle parameter specifically includes:
acquiring the total driving torque of the vehicle; the total driving torque of the vehicle is the total driving torque corresponding to the opening degree of an accelerator pedal of the distributed driving electric automobile;
determining a generalized additional yaw moment of the vehicle according to the vehicle parameters;
when the failure condition of the driving motor of the distributed driving electric automobile is single motor failure, a formula is utilized according to the total driving torque of the automobile and the generalized additional yaw moment
Figure BDA0002041055800000021
Determining torque signals for individual drive motors
Figure BDA0002041055800000031
Wherein the torques of two drive motors on different sides of the failed motor are equal, lambda1Is the failure factor, lambda, of the front left drive motor2Is the failure factor, lambda, of the right front drive motor3Is the failure factor, lambda, of the rear left drive motor4Is the failure factor of the right rear driving motor; b isfFor front track, BrFor rear track, R0Is the rolling radius of the wheel, T1Is the torque signal of the front left drive motor, T2Is the torque signal of the right front drive motor, T3Torque signal for the left rear drive motor, T4Torque signal for the rear right drive motor, TexpThe delta M is a generalized additional yaw moment for the total driving torque of the vehicle;
when the failure condition of the driving motor of the distributed driving electric automobile is the failure of the double motors on different sides, a formula is utilized according to the total driving torque of the automobile and the generalized additional yaw moment
Figure BDA0002041055800000032
Determining torque signals for individual drive motors
Figure BDA0002041055800000033
Optionally, the determining a generalized additional yaw moment of the vehicle according to the vehicle parameter specifically includes:
determining the rotation angle of the front wheel of the vehicle according to the rotation angle of a steering wheel of the vehicle;
determining an expected yaw velocity of the vehicle in the current state based on a two-degree-of-freedom model according to the front wheel turning angle and the vehicle speed of the vehicle;
determining a generalized additional yaw moment of the vehicle using a PID control algorithm based on an actual yaw rate of the vehicle and the desired yaw rate.
The invention also provides a control system for distributed driving of an electric vehicle in a motor failure state, comprising:
the driving motor failure condition acquisition module is used for acquiring the failure condition of the driving motor of the distributed driving electric automobile; the drive motor failure condition includes: single motor failure, double motor failure on different sides and uncontrollable failure; the uncontrollable failures comprise two-motor failures, three-motor failures and four-motor failures on the same side;
the first torque signal determining module is used for determining that the torque signals of all the driving motors are zero when the failure condition of the driving motors of the distributed driving electric automobile is uncontrollable failure;
the vehicle parameter acquisition module is used for acquiring vehicle parameters of the distributed driving electric automobile when the failure condition of the driving motor of the distributed driving electric automobile is single motor failure or double motors on different sides are failed; the vehicle parameters comprise a vehicle steering wheel angle, a vehicle speed and a vehicle actual yaw rate;
the second torque signal determining module is used for determining torque signals of all driving motors according to failure conditions of the driving motors of the distributed driving electric automobile and the vehicle parameters;
and the torque adjusting module is used for adjusting the torque of each driving motor of the distributed driving electric automobile according to the torque signal of each driving motor.
Optionally, the method further includes:
the motor failure factor acquisition module is used for acquiring a motor failure factor of each motor controller before acquiring the failure condition of a driving motor of the distributed driving electric automobile;
the driving motor failure condition determining module is used for determining the failure condition of each driving motor of the distributed driving electric automobile according to the value of the motor failure factor; when the value of the motor failure factor is 1, determining that the corresponding driving motor has no failure; and when the value of the motor failure factor is 0, determining that the corresponding driving motor fails.
Optionally, the second torque signal determination module specifically includes:
a vehicle total drive torque acquisition unit for acquiring a vehicle total drive torque; the total driving torque of the vehicle is the total driving torque corresponding to the opening degree of an accelerator pedal of the distributed driving electric automobile;
the generalized additional yaw moment determining unit is used for determining the generalized additional yaw moment of the vehicle according to the vehicle parameters;
a first torque signal determination unit for, when the failure condition of the driving motor of the distributed drive electric vehicle is a single motor failure, utilizing a formula based on the total driving torque of the vehicle and the generalized additional yaw moment
Figure BDA0002041055800000051
Determining torque signals for individual drive motors
Figure BDA0002041055800000052
Wherein the torques of two drive motors on different sides of the failed motor are equal, lambda1Is the failure factor, lambda, of the front left drive motor2Is the failure factor, lambda, of the right front drive motor3Is the failure factor, lambda, of the rear left drive motor4Is the failure factor of the right rear driving motor; b isfFor front track, BrFor rear track, R0Is the rolling radius of the wheel, T1Is the torque signal of the front left drive motor, T2Is the torque signal of the right front drive motor, T3Torque signal for the left rear drive motor, T4Torque signal for the rear right drive motor, TexpThe delta M is a generalized additional yaw moment for the total driving torque of the vehicle;
a second torque signal determination unit for utilizing a formula according to the total driving torque of the vehicle and the generalized additional yaw moment when the failure condition of the driving motor of the distributed driving electric vehicle is the failure of the two motors on the opposite sides
Figure BDA0002041055800000053
Determining torque signals for individual drive motors
Figure BDA0002041055800000054
Optionally, the generalized additional yaw moment determining unit specifically includes:
a vehicle front wheel steering angle determining subunit for determining a vehicle front wheel steering angle from the vehicle steering wheel steering angle;
the expected yaw rate determining subunit is used for determining an expected yaw rate of the vehicle in the current state based on the two-degree-of-freedom model according to the front wheel turning angle of the vehicle and the vehicle speed;
and the generalized additional yaw moment determining sub-unit is used for determining the generalized additional yaw moment of the vehicle by utilizing a PID control algorithm according to the actual yaw velocity and the expected yaw velocity of the vehicle.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention relates to a fault-tolerant control method for failure of a driving motor of a four-hub motor distributed driving electric automobile, which ensures the original dynamic property of the automobile under most conditions by total torque constraint and ensures the stability of the automobile by additional yaw moment constraint.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments 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 it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a schematic flow chart of a control method for a distributed drive electric vehicle in a motor failure state according to the present invention;
FIG. 2 is a schematic structural diagram of a control system of a distributed drive electric vehicle in a motor failure state according to the present invention;
FIG. 3 is a schematic flow chart of an embodiment of the present invention;
FIG. 4 is a diagram of a two-degree-of-freedom model according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
The invention mainly aims at carrying out corresponding control when a driving motor of a four-hub motor/wheel-side motor driving automobile fails, and finally, the control is realized by a method for reconstructing the torque of the residual driving motor of the automobile. First, the hardware devices included in the present invention are: the system comprises motor controllers of four hub/wheel-side motors, a vehicle steering wheel rotation angle sensor, a vehicle yaw angular velocity sensor and a vehicle controller.
The four motor controllers are arranged on a vehicle chassis and transmit the motor failure factor to the vehicle control unit through Can lines. The motor failure factor is a flag bit indicating whether the motor fails or not given by a fault diagnosis module of the motor controller, the module belongs to the prior art, flag bit information indicating whether the motor can work or not given by the motor controller according to the current fault state of the motor, the motor failure factor is 0 when the motor fails, and the motor failure factor is 1 when the motor is normal. The controller receives a torque control signal of the whole vehicle controller to generate motor torque; the vehicle steering wheel angle sensor is arranged on a vehicle steering wheel and transmits a steering wheel angle signal to the whole vehicle controller through a Can line; the vehicle yaw velocity sensor is arranged near the position of the mass center of the vehicle and transmits a yaw velocity value to the vehicle controller through a Can line; and finally, the vehicle control unit is arranged in a front cabin of the vehicle, is connected with the four motor controllers through Can lines and sends corresponding torque commands to the four motor controllers.
Fig. 1 is a schematic flow chart of a control method of a distributed drive electric vehicle in a motor failure state according to the present invention. As shown in fig. 1, the control method includes the steps of:
step 100: and acquiring the failure condition of the driving motor of the distributed driving electric automobile. The process of judging the failure condition of the driving motor is as follows: firstly, acquiring a motor failure factor of each motor controller; then, determining the failure condition of each driving motor of the distributed driving electric automobile according to the value of the motor failure factor; when the value of the motor failure factor is 1, determining that the corresponding driving motor has no failure; and when the value of the motor failure factor is 0, determining that the corresponding driving motor fails.
The electric automobile provided by the invention has four driving motors, and when the driving motors fail, the failure conditions of the driving motors can be divided into the following three categories.
1) Single motor failure
At this time, one of the four motor failure factors is 0, that is, a single motor fails.
2) Failure of two motors on different sides
At this time, two of the failure factors of the four motors are 0, and the two failed motors are respectively positioned at two sides of the vehicle.
3) Uncontrolled failure
Under the condition of vehicle failure, the vehicle cannot be controlled, and the vehicle failure control system consists of double-motor failure, three-motor failure and the most serious four-motor failure on the same side.
When no motor fails, the four motor failure factors are all 1, no motor fails, and the vehicle is distributed according to normal torque.
Step 200: and when the failure condition of the driving motors of the distributed driving electric automobile is uncontrollable failure, determining that the torque signals of all the driving motors are zero. For the uncontrollable failure condition, in order to ensure the safety of the whole vehicle, the torque commands sent by the whole vehicle controller to the four motor controllers are all 0, so that the vehicle can be quickly stopped.
Step 300: and when the failure condition of the driving motor of the distributed driving electric automobile is single motor failure or double motors on different sides are failed, acquiring vehicle parameters of the distributed driving electric automobile. The vehicle parameters include a vehicle steering wheel angle, a vehicle speed, and an actual yaw rate of the vehicle.
Step 400: and determining the torque signals of the driving motors according to the failure conditions of the driving motors of the distributed driving electric automobile and vehicle parameters. The original dynamic property of the vehicle is ensured through total torque constraint, the stability of the vehicle is ensured through additional yaw moment constraint, and then the torque signals of the driving motors are determined, and the method is as follows:
acquiring the total driving torque of the vehicle; the total driving torque of the vehicle is the total driving torque corresponding to the opening degree of an accelerator pedal of the distributed driving electric automobile;
determining a generalized additional yaw moment of the vehicle according to the vehicle parameters;
when the failure condition of the driving motor of the distributed driving electric automobile is single motor failure, a formula is utilized according to the total driving torque of the automobile and the generalized additional yaw moment
Figure BDA0002041055800000081
Determining torque signals for individual drive motors
Figure BDA0002041055800000082
Wherein the torques of two drive motors on different sides of the failed motor are equal, lambda1Is the failure factor, lambda, of the front left drive motor2Is the failure factor, lambda, of the right front drive motor3Is the failure factor, lambda, of the rear left drive motor4Is the failure factor of the right rear driving motor; b isfFor front track, BrFor rear track, R0Is the rolling radius of the wheel, T1Is the torque signal of the front left drive motor, T2Is the torque signal of the right front drive motor, T3Torque signal for the left rear drive motor, T4Torque signal for the rear right drive motor, TexpThe delta M is a generalized additional yaw moment for the total driving torque of the vehicle;
when the failure condition of the driving motor of the distributed driving electric automobile is the failure of the double motors on different sides, a formula is utilized according to the total driving torque of the automobile and the generalized additional yaw moment
Figure BDA0002041055800000091
Determining torque signals for individual drive motors
Figure BDA0002041055800000092
Step 500: and adjusting the torque of each driving motor of the distributed driving electric automobile according to the torque signal of each driving motor.
Fig. 2 is a schematic structural diagram of a control system of a distributed drive electric vehicle in a motor failure state according to the present invention. As shown in fig. 2, the control system includes the following structure:
a driving motor failure condition obtaining module 201, configured to obtain a driving motor failure condition of the distributed driving electric vehicle; the drive motor failure condition includes: single motor failure, double motor failure on different sides and uncontrollable failure; the uncontrollable failures comprise two-motor failures, three-motor failures and four-motor failures on the same side;
the first torque signal determining module 202 is configured to determine that torque signals of all driving motors are zero when a failure condition of the driving motors of the distributed driving electric vehicle is an uncontrollable failure;
the vehicle parameter acquiring module 203 is configured to acquire a vehicle parameter of the distributed drive electric vehicle when a failure condition of a drive motor of the distributed drive electric vehicle is a single motor failure or a dual motor failure on an opposite side; the vehicle parameters comprise a vehicle steering wheel angle, a vehicle speed and a vehicle actual yaw rate;
the second torque signal determination module 204 is configured to determine a torque signal of each driving motor according to a failure condition of the driving motor of the distributed driving electric vehicle and the vehicle parameter;
and the torque adjusting module 205 is used for adjusting the torque of each driving motor of the distributed driving electric automobile according to the torque signal of each driving motor.
The system further comprises:
the motor failure factor acquisition module is used for acquiring a motor failure factor of each motor controller before acquiring the failure condition of a driving motor of the distributed driving electric automobile;
the driving motor failure condition determining module is used for determining the failure condition of each driving motor of the distributed driving electric automobile according to the value of the motor failure factor; when the value of the motor failure factor is 1, determining that the corresponding driving motor has no failure; and when the value of the motor failure factor is 0, determining that the corresponding driving motor fails.
The second torque signal determination module 204 specifically includes:
a vehicle total drive torque acquisition unit for acquiring a vehicle total drive torque; the total driving torque of the vehicle is the total driving torque corresponding to the opening degree of an accelerator pedal of the distributed driving electric automobile;
the generalized additional yaw moment determining unit is used for determining the generalized additional yaw moment of the vehicle according to the vehicle parameters;
a first torque signal determination unit for, when the failure condition of the driving motor of the distributed drive electric vehicle is a single motor failure, utilizing a formula based on the total driving torque of the vehicle and the generalized additional yaw moment
Figure BDA0002041055800000101
Determining torque signals for individual drive motors
Figure BDA0002041055800000102
Wherein the torques of two drive motors on different sides of the failed motor are equal, lambda1Is the failure factor, lambda, of the front left drive motor2Is the failure factor, lambda, of the right front drive motor3Is the failure factor, lambda, of the rear left drive motor4Is the failure factor of the right rear driving motor; b isfFor front track, BrFor rear track, R0Is the rolling radius of the wheel, T1Is a left front drive motorTorque signal of (T)2Is the torque signal of the right front drive motor, T3Torque signal for the left rear drive motor, T4Torque signal for the rear right drive motor, TexpThe delta M is a generalized additional yaw moment for the total driving torque of the vehicle;
a second torque signal determination unit for utilizing a formula according to the total driving torque of the vehicle and the generalized additional yaw moment when the failure condition of the driving motor of the distributed driving electric vehicle is the failure of the two motors on the opposite sides
Figure BDA0002041055800000111
Determining torque signals for individual drive motors
Figure BDA0002041055800000112
The generalized additional yaw moment determination unit specifically includes:
a vehicle front wheel steering angle determining subunit for determining a vehicle front wheel steering angle from the vehicle steering wheel steering angle;
the expected yaw rate determining subunit is used for determining an expected yaw rate of the vehicle in the current state based on the two-degree-of-freedom model according to the front wheel turning angle of the vehicle and the vehicle speed;
and the generalized additional yaw moment determining sub-unit is used for determining the generalized additional yaw moment of the vehicle by utilizing a PID control algorithm according to the actual yaw velocity and the expected yaw velocity of the vehicle.
The invention is further illustrated below with reference to a specific embodiment.
FIG. 3 is a flow chart illustrating an embodiment of the present invention. As shown in fig. 3, the present embodiment includes the following steps:
the first step is as follows: the vehicle control unit acquires a motor failure factor of the motor controller and judges the failure condition of a vehicle driving motor according to the acquired motor failure factor.
1) No motor failure
At the moment, the failure factors of the four motors are 1, no motor fails, the vehicle does not trigger a failure control program according to normal torque distribution, and the second step is not carried out.
2) Single motor failure
At the moment, one of the four motor failure factors is 0, namely, the single motor has a failure condition, and when the failure condition occurs, a failure control program is triggered to enter.
3) Failure of two motors on different sides
At the moment, two failure factors of the four motors are 0, the two failed motors are respectively positioned at two sides of the vehicle, and a failure control program is triggered when the failure condition occurs.
4) Uncontrolled failure
Under the condition of the vehicle failure, the vehicle cannot be controlled, the vehicle is composed of the conditions of dual-motor failure, three-motor failure and the most serious four-motor failure on the same side, and the failure conditions trigger failure control strategies.
And secondly, after the vehicle controller obtains the current failure mode of the vehicle, the vehicle controller selects corresponding control methods for the three major failure conditions entering failure control.
For the uncontrollable failure condition, in order to ensure the safety of the whole vehicle, the torque commands sent by the whole vehicle controller to the four motor controllers are all 0, so that the vehicle can be quickly stopped, and the fourth step is not carried out to return to the first step under the failure condition.
After the single motor failure condition is judged, the corresponding single motor failure control method in the fourth step is carried out; and entering the different-side double-motor failure control method in the fourth step after the situation that the different-side double-motor failure occurs is judged.
The third step: the control for the above two failure cases aims to ensure drivability and yaw stability of the vehicle. The maintenance of the drivability of the vehicle is determined by the vehicle generalized longitudinal force, and the yaw stability is determined by the generalized yaw moment, which has the following relationship with the torques of the four drive motors of the vehicle:
Figure BDA0002041055800000121
in the formula, R0Is the wheel rolling radius; b isfIs the front wheel track; b isrIs the rear wheel track; t isexpThe total driving torque of the vehicle is the total driving torque of the vehicle, and the total driving torque of the vehicle required by the vehicle controller is provided by a pedal analysis module in the vehicle controller; Δ M is the generalized additional yaw moment required to maintain yaw stability of the vehicle; lambda [ alpha ]1Is the failure factor, lambda, of the front left drive motor2Is the failure factor, lambda, of the right front drive motor3Is the failure factor, lambda, of the rear left drive motor4Is the failure factor of the right rear driving motor; t is1Is the torque signal of the front left drive motor, T2Is the torque signal of the right front drive motor, T3Torque signal for the left rear drive motor, T4Is the torque signal of the right rear drive motor.
At the moment, the generalized longitudinal force is calculated by the total driving torque of the vehicle given by the pedal analysis strategy of the vehicle controller, and the generalized additional yaw moment is calculated by the corresponding control strategy.
The generalized additional yaw moment is obtained by PID control with the expected yaw rate as a control target, and the generalized additional yaw moment obtaining process is shown as follows.
Firstly, the vehicle control unit obtains a vehicle steering wheel corner according to the information of a steering wheel corner sensor, and obtains a vehicle front wheel corner through a table look-up model; in addition, the vehicle obtains the value of the expected yaw rate under the current state of the vehicle based on the two-degree-of-freedom model according to the vehicle speed obtained by a vehicle speed calculation module in the vehicle controller, and the calculation formula of the value of the expected yaw rate is as follows:
Figure BDA0002041055800000131
in the formula LfAnd LrDistances, v, from the center of mass of the vehicle to the front and rear axles, respectivelyxIs the longitudinal speed of the vehicle, m is the mass of the whole vehicle,
Figure BDA0002041055800000132
and
Figure BDA0002041055800000133
the cornering stiffness of the tires of the front axle and the rear axle, respectively, where the cornering stiffness of the tires is the sum of the cornering stiffnesses of the two tires of the front axle/the rear axle, δ is the front wheel angle of the vehicle, γdIs the desired yaw rate.
FIG. 4 is a schematic diagram of a two degree of freedom model. As shown in fig. 4, the two-degree-of-freedom model is a prior art in stability control that is already in the field of vehicle engineering, and the two-degree-of-freedom model can exhibit a response characteristic of a linear region of a vehicle, which is a characteristic of a vehicle with which most drivers are familiar. The two-degree-of-freedom model has the degrees of freedom in the lateral direction and the transverse direction, and the vehicle speed in the longitudinal direction is constant. The method is a single-wheel vehicle model obtained by simplifying a four-wheel vehicle model.
The acting force applied to the vehicle is only applied by the lateral force of front and rear tires, the lateral force of the tires is determined by the slip angle of the tires, and the slip angle of the tires is determined by the self-motion state of the vehicle such as the yaw velocity of the vehicle. Therefore, a two-degree-of-freedom vehicle model dynamics formula can be calculated based on the above relationship. The dynamic analysis is carried out on the model, so that the steady-state yaw rate requirement of the vehicle shown in the formula (2) in a certain vehicle speed and steering wheel angle state can be finally obtained, and the requirement is finally used as the target yaw rate of the vehicle.
After the expected yaw rate is obtained by the formula (2), the difference e between the expected yaw rate and the actual yaw rate of the vehicle, received by the vehicle controller, of the yaw rate sensor is changed into gammad- γ, which is then input into the PID control algorithm to derive the value of its generalized additional yaw moment. The calculation formula is as follows:
Figure BDA0002041055800000134
Kp、Ki、Kdrespectively proportional, integral and micro in PID control algorithmAnd the coefficient of the submodules is a fixed value calibrated on site.
The total driving torque required for the vehicle and the generalized additional yaw moment are obtained so far, and the above-described control amounts are entered into the specific control method in the fourth step.
The fourth step: after the failure conditions in the second step are determined, the corresponding control methods are respectively selected, and the two failure conditions of the control methods are as follows:
1. single motor failure control method
After the vehicle failure condition is determined to be single motor failure in the second step, the control method in the present section solves the distributed torque signals of the wheels by the constraint equation in the formula (1) with the total vehicle driving torque and the generalized additional yaw moment calculated in the third step as targets.
Since there are two equations but three unknowns in equation (1) at this time because the torque distribution of the motor with failure must be 0, equation 1 can have countless solutions, so that a rule is introduced at this time that the two motors with non-failure side distributed have equal torque. According to this rule, the corresponding calculation equation can therefore be given as follows:
Figure BDA0002041055800000141
according to the formula (4), after the single motor fails, the formula (4) has a unique solution through the rule that the sizes of the motor torques on the non-failed sides are equal, and after the torque signals of the driving motors are obtained, the vehicle control unit sends the torque signals to the motor controllers.
2. Different-side double-wheel failure control method
After the second step determines that the two wheels on the different sides are in failure, the control method of the part takes the total driving torque of the vehicle and the generalized additional yaw moment calculated in the third step as targets, and the distributed torque signals of the wheels are solved through the constraint equation in the formula (1). At the moment, the torque of the vehicle is determined to be 0 when the vehicle has two failed motors, the unknown number in the formula 1 is the same as the equation number, the formula 1 can be directly solved to obtain corresponding motor torque signals, and the calculation equation is shown as follows
Figure BDA0002041055800000151
After the torque signals of the motors are calculated by the formula (5), the vehicle control unit sends the distributed torque signals of the motors to the corresponding motor controllers.
After the control method obtains the torque command signals corresponding to the motors, the first step is repeated to complete the circulation of the whole control strategy.
For a distributed drive electric automobile, four hub/wheel-side motors directly drive wheels and determine the driving force of the wheels, and in addition, the possibility of failure of the driving motors of the vehicle is increased due to the large number of driving motors of the vehicle, namely the hub motors, and the severe working environment. The invention can still maintain the dynamic property and the yaw stability of the distributed drive electric automobile under the condition that the motor of the distributed drive electric automobile fails.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (6)

1. A control method for a distributed driving electric automobile in a motor failure state is characterized by comprising the following steps:
acquiring the failure condition of a driving motor of the distributed driving electric automobile; the drive motor failure condition includes: single motor failure, double motor failure on different sides and uncontrollable failure; the uncontrollable failures comprise two-motor failures, three-motor failures and four-motor failures on the same side;
when the failure condition of the driving motors of the distributed driving electric automobile is uncontrollable failure, determining that the torque signals of all the driving motors are zero;
when the failure condition of the driving motor of the distributed driving electric automobile is single motor failure or double motors on different sides are failed, vehicle parameters of the distributed driving electric automobile are obtained; the vehicle parameters comprise a vehicle steering wheel angle, a vehicle speed and a vehicle actual yaw rate;
determining torque signals of all driving motors according to the failure conditions of the driving motors of the distributed driving electric automobile and the vehicle parameters; the method specifically comprises the following steps: acquiring total driving torque of a vehicle, wherein the total driving torque of the vehicle is the total driving torque corresponding to the opening degree of an accelerator pedal of the distributed driving electric automobile; determining a generalized additional yaw moment of the vehicle according to the vehicle parameters; when the failure condition of the driving motor of the distributed driving electric automobile is single motor failure, a formula is utilized according to the total driving torque of the automobile and the generalized additional yaw moment
Figure FDA0002725985000000011
Determining torque signals for individual drive motors
Figure FDA0002725985000000012
Wherein the torques of two drive motors on different sides of the failed motor are equal, lambda1Is the failure factor, lambda, of the front left drive motor2Is the failure factor, lambda, of the right front drive motor3Is the failure factor, lambda, of the rear left drive motor4Is the failure factor of the right rear driving motor; b isfFor front track, BrFor rear track, R0Is the rolling radius of the wheel, T1Is the torque signal of the front left drive motor, T2Is the torque signal of the right front drive motor, T3Torque signal for the left rear drive motor, T4Torque signal for the rear right drive motor, TexpThe delta M is a generalized additional yaw moment for the total driving torque of the vehicle; when the failure condition of the driving motor of the distributed driving electric automobile is the failure of the double motors on different sides, a formula is utilized according to the total driving torque of the automobile and the generalized additional yaw moment
Figure FDA0002725985000000021
Determining torque signals for individual drive motors
Figure FDA0002725985000000022
And adjusting the torque of each driving motor of the distributed driving electric automobile according to the torque signal of each driving motor.
2. The method for controlling the distributed-drive electric vehicle in the motor failure state according to claim 1, wherein the obtaining of the failure condition of the drive motor of the distributed-drive electric vehicle further comprises:
acquiring a motor failure factor of each motor controller;
determining the failure condition of each driving motor of the distributed driving electric automobile according to the value of the motor failure factor; when the value of the motor failure factor is 1, determining that the corresponding driving motor has no failure; and when the value of the motor failure factor is 0, determining that the corresponding driving motor fails.
3. The method for controlling the distributed-drive electric vehicle in the motor failure state according to claim 2, wherein the determining the generalized additional yaw moment of the vehicle according to the vehicle parameters specifically comprises:
determining the rotation angle of the front wheel of the vehicle according to the rotation angle of a steering wheel of the vehicle;
determining an expected yaw velocity of the vehicle in the current state based on a two-degree-of-freedom model according to the front wheel turning angle and the vehicle speed of the vehicle;
determining a generalized additional yaw moment of the vehicle using a PID control algorithm based on an actual yaw rate of the vehicle and the desired yaw rate.
4. A control system for a distributed drive electric vehicle in a motor failure state, comprising:
the driving motor failure condition acquisition module is used for acquiring the failure condition of the driving motor of the distributed driving electric automobile; the drive motor failure condition includes: single motor failure, double motor failure on different sides and uncontrollable failure; the uncontrollable failures comprise two-motor failures, three-motor failures and four-motor failures on the same side;
the first torque signal determining module is used for determining that the torque signals of all the driving motors are zero when the failure condition of the driving motors of the distributed driving electric automobile is uncontrollable failure;
the vehicle parameter acquisition module is used for acquiring vehicle parameters of the distributed driving electric automobile when the failure condition of the driving motor of the distributed driving electric automobile is single motor failure or double motors on different sides are failed; the vehicle parameters comprise a vehicle steering wheel angle, a vehicle speed and a vehicle actual yaw rate;
the second torque signal determining module is used for determining torque signals of all driving motors according to failure conditions of the driving motors of the distributed driving electric automobile and the vehicle parameters; the second torque signal determination module specifically includes: a vehicle total drive torque acquisition unit for acquiring a vehicle total drive torque; the total driving torque of the vehicle is the total driving torque corresponding to the opening degree of an accelerator pedal of the distributed driving electric automobile; the generalized additional yaw moment determining unit is used for determining the generalized additional yaw moment of the vehicle according to the vehicle parameters; a first torque signal determination unit for utilizing a common yaw moment based on the total vehicle drive torque and the generalized additional yaw moment when the failure condition of the drive motor of the distributed drive electric vehicle is a single motor failureFormula (II)
Figure FDA0002725985000000031
Determining torque signals for individual drive motors
Figure FDA0002725985000000032
Wherein the torques of two drive motors on different sides of the failed motor are equal, lambda1Is the failure factor, lambda, of the front left drive motor2Is the failure factor, lambda, of the right front drive motor3Is the failure factor, lambda, of the rear left drive motor4Is the failure factor of the right rear driving motor; b isfFor front track, BrFor rear track, R0Is the rolling radius of the wheel, T1Is the torque signal of the front left drive motor, T2Is the torque signal of the right front drive motor, T3Torque signal for the left rear drive motor, T4Torque signal for the rear right drive motor, TexpThe delta M is a generalized additional yaw moment for the total driving torque of the vehicle; a second torque signal determination unit for utilizing a formula according to the total driving torque of the vehicle and the generalized additional yaw moment when the failure condition of the driving motor of the distributed driving electric vehicle is the failure of the two motors on the opposite sides
Figure FDA0002725985000000041
Determining torque signals for individual drive motors
Figure FDA0002725985000000042
And the torque adjusting module is used for adjusting the torque of each driving motor of the distributed driving electric automobile according to the torque signal of each driving motor.
5. The control system for a distributed drive electric vehicle in the motor failure state according to claim 4, further comprising:
the motor failure factor acquisition module is used for acquiring a motor failure factor of each motor controller before acquiring the failure condition of a driving motor of the distributed driving electric automobile;
the driving motor failure condition determining module is used for determining the failure condition of each driving motor of the distributed driving electric automobile according to the value of the motor failure factor; when the value of the motor failure factor is 1, determining that the corresponding driving motor has no failure; and when the value of the motor failure factor is 0, determining that the corresponding driving motor fails.
6. The control system for a distributed drive electric vehicle in a motor failure state according to claim 5, wherein the generalized additional yaw moment determination unit specifically includes:
a vehicle front wheel steering angle determining subunit for determining a vehicle front wheel steering angle from the vehicle steering wheel steering angle;
the expected yaw rate determining subunit is used for determining an expected yaw rate of the vehicle in the current state based on the two-degree-of-freedom model according to the front wheel turning angle of the vehicle and the vehicle speed;
and the generalized additional yaw moment determining sub-unit is used for determining the generalized additional yaw moment of the vehicle by utilizing a PID control algorithm according to the actual yaw velocity and the expected yaw velocity of the vehicle.
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