CN110654370A - Hybrid vehicle control method and system with low-attachment road surface - Google Patents

Hybrid vehicle control method and system with low-attachment road surface Download PDF

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Publication number
CN110654370A
CN110654370A CN201810691141.0A CN201810691141A CN110654370A CN 110654370 A CN110654370 A CN 110654370A CN 201810691141 A CN201810691141 A CN 201810691141A CN 110654370 A CN110654370 A CN 110654370A
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China
Prior art keywords
road surface
low
hybrid vehicle
slip rate
threshold value
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Inventor
张慧君
孙玉
张英富
徐波
郝之凯
王立波
周铁
田伟娜
魏树林
孟祥禄
李熙
王娴
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Great Wall Motor Co Ltd
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Great Wall Motor Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W20/00—Control systems specially adapted for hybrid vehicles
    • B60W20/10—Controlling the power contribution of each of the prime movers to meet required power demand
    • B60W20/13—Controlling the power contribution of each of the prime movers to meet required power demand in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
    • B60W20/14—Controlling the power contribution of each of the prime movers to meet required power demand in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion in conjunction with braking regeneration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
    • B60W30/18—Propelling the vehicle
    • B60W30/18009—Propelling the vehicle related to particular drive situations
    • B60W30/18109—Braking
    • B60W30/18127—Regenerative braking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
    • B60W40/02—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to ambient conditions
    • B60W40/06—Road conditions
    • B60W40/064—Degree of grip
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2520/00—Input parameters relating to overall vehicle dynamics
    • B60W2520/26—Wheel slip
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2540/00—Input parameters relating to occupants
    • B60W2540/10—Accelerator pedal position
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2540/00—Input parameters relating to occupants
    • B60W2540/12—Brake pedal position
    • 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
    • Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
    • Y02T10/84—Data processing systems or methods, management, administration

Abstract

The invention relates to the technical field of hybrid vehicles, and provides a control method and a control system for a hybrid vehicle with a low road surface. The hybrid vehicle control method of the present invention is directed to a P0+ P4 power configuration, and includes: identifying whether the current road surface is a low-adhesion road surface; and when the current road surface is a low-adhesion road surface, adjusting the output torque of an engine to reduce the front wheel end torque of the hybrid vehicle, adjusting the torque rising slope and the output torque of a rear axle motor to reduce the rear wheel end torque of the hybrid vehicle, and/or reducing the intensity of braking energy recovery for the hybrid vehicle or prohibiting the braking energy recovery function of the hybrid vehicle. The invention identifies the low-attachment road surface which is easy to generate the tail flick, specially processes the torque of the shaft end of the engine and the motor of the rear shaft aiming at the low-attachment road surface, reduces the slip probability of the front wheel end, ensures the stability of the rear wheel, optimizes the energy recovery strategy and avoids the instability of the vehicle caused by excessive energy recovery.

Description

Hybrid vehicle control method and system with low-attachment road surface
Technical Field
The invention relates to the technical field of hybrid vehicles, in particular to a control method and a control system of a hybrid vehicle with a low-attachment road surface.
Background
At present, for hybrid electric vehicles, the hybrid electric vehicles can be divided into four power configurations, namely, P0, P1, P2, P3 and P4, according to the arrangement position of a motor in a power system. Wherein, for P0, it is also called Belt-driven Starter Generator (BSG), the motor is arranged at the front end of the engine and coupled with the crankshaft of the engine through a Belt; for P4, the electric machine is disposed at the rear Axle to provide torque to Drive the vehicle simultaneously with the engine, and also can be used as the driving module to output power independently, which is also called electric Axle Drive (eAD). For the hybrid electric four-wheel drive System of the P0+ P4 power configuration, the front axle power is derived from a conventional Engine Management System (EM)S) and BSG, front axle end total torque T, belt-driven therewithFAFor engine output torque TEngTrqAnd BSG output torque TBSGTrqSum, i.e. TFA＝TEngTrq+TBSGTrq(ii) a The rear wheel is driven by a Motor Control Unit (MCU) to run, and the Motor torque TRAThe energy storage battery pack is derived from a high-voltage battery pack, the battery pack can be charged by an external power supply through a vehicle-mounted charger, and can also be used for energy storage through BSG power generation and energy recovery during driving. The whole vehicle torque is coordinated through a Hybrid Control Unit (HCU) Control strategy, the front axle and rear axle power output is independently controlled according to a certain proportion, the front axle torque is transmitted to a front wheel through a Transmission Control Unit (TCU), and the rear axle torque is transmitted to a rear axle through a rear Axle Control Unit (ACU).
At present, the performance calibration of the whole vehicle is divided into low-adhesion-coefficient pavements (such as ice surfaces, snow surfaces and the like, hereinafter referred to as low-adhesion pavements) and high-adhesion-coefficient pavements (such as asphalt, gravel and the like, hereinafter referred to as high-adhesion pavements). The power system (such as HCU, EMS, BSG and MCU) and the transmission system (such as TCU and ACU) do not distinguish according to the road adhesion coefficient, but the vehicle Stability control unit (Electronic Stability Program, ESP) can identify and control the performance of the vehicle on the high and low road surfaces, wherein the high and low road surfaces are identified mainly according to the slip rate, the deceleration and the change rate of the deceleration, and the whole vehicle acceleration, operation Stability and brake performance calibration is carried out according to the road identification result, so that the vehicle Stability effect is improved.
Although the identification method can realize the braking action, the following defects exist:
1) when the vehicle runs on a low-attachment road surface, compared with a high-attachment road surface, under the condition of the same vehicle speed and the same accelerator opening degree, the wheel end torque is too large, so that the wheel slips, the ESP is frequently involved in work, the working frequency of an ESP motor is increased to a certain extent, and meanwhile, the working Noise of the motor can also have certain influence on NVH (Noise, Vibration and Harshness) of a hybrid vehicle.
2) Since the external characteristic curve of the engine is determined by hardware, the pedal map of the designed fixed-model engine has the same road torque output characteristic at different adhesion coefficients. However, as for the motor, the torque response is fast, dangerous situations such as rear wheel slipping and even tail flicking easily occur during low-level steering, and at the moment, the ESP is frequently involved in control, discontinuous and abrupt changes of wheel torque occur, and serious rushing and clattering noise occur in the whole vehicle.
3) On a low-attachment road surface, when the HCU (hybrid control unit) is used for recovering the sliding energy, a certain braking force is generated, at the moment, a rear axle generates a larger braking force, the wheels are easy to lock, and the vehicle is easy to be unstable due to over-steering.
Disclosure of Invention
In view of the above, the present invention is directed to a method for controlling a hybrid vehicle with a low road surface, so as to at least partially solve the above technical problems.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a low-attachment-road hybrid vehicle control method is directed to a P0+ P4 power configuration of a hybrid vehicle in which a front-axis power of the hybrid vehicle is derived from an engine and a rear-axis power is derived from a rear-axis motor, and the P0+ P4 power configuration. Further, the method for controlling a hybrid vehicle on a low-adhesion road surface includes: identifying whether the current road surface is a low-adhesion road surface; and when the current road surface is the low-adhesion road surface, executing any one or more of the following:
adjusting an output torque of the engine to reduce a front wheel end torque of the hybrid vehicle;
adjusting the torque rising slope and the output torque of the rear axle motor to reduce the rear wheel end torque of the hybrid vehicle; and
reducing an intensity of braking energy recovery for the hybrid vehicle or prohibiting a braking energy recovery function of the hybrid vehicle.
Further, the identifying whether the current road surface is a low-adhesion road surface includes: in the starting process of the vehicle, when an opening signal of an accelerator pedal is in a corresponding preset range and the opening of a brake pedal is 0, if a wheel slips, calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the count, otherwise, subtracting 1 from the count, and when the count value is greater than the preset count threshold value, judging that the current road surface is a low-attachment road surface; in the vehicle braking process, when a brake pedal opening signal is in a corresponding preset range and the accelerator pedal opening is 0, if wheels are locked, calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the counting, otherwise, subtracting 1 from the counting, and when the counting value is greater than the preset counting threshold value, judging that the current road surface is a low-attachment road surface; in the vehicle sliding process, when the opening degree of a brake pedal is 0 and the opening degree of an accelerator pedal is 0, if wheels are locked, calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the count, otherwise, subtracting 1 from the count, and when the count value is greater than the preset count threshold value, judging that the current road surface is a low-attachment road surface; and in the normal running process of the vehicle, when the vehicle speed is greater than a preset vehicle speed threshold value, the vehicle turns, the opening degree of a brake pedal is 0 and the driver is judged to be at the accelerator pedal, if wheels are locked, calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the count, otherwise, subtracting 1 from the count, and when the count value is greater than the preset count threshold value, judging that the current road surface is a low-attachment road surface
Further, the adjusting the output torque of the engine includes: and adjusting the pedal diagram curve of the engine to ensure that the engine output torque of the low-attachment road surface is lower than that of the common road surface under the same accelerator pedal opening.
Further, the adjusting the torque rising slope and the output torque of the rear axle motor includes: if the steering wheel rotating angle of the hybrid vehicle is larger than the corresponding set value and the steering wheel rotating speed of the hybrid vehicle is smaller than the corresponding set value, judging that the current low-adhesion road surface is a low-adhesion turning road surface, slowing down the torque rising slope of the rear axle motor aiming at the low-adhesion turning road surface, and reducing the output torque of the rear axle motor.
Compared with the prior art, the control method of the hybrid vehicle with the low-attachment road surface has the following advantages:
(1) the control method of the hybrid vehicle with the low-adhesion road surface identifies the low-adhesion road surface which is easy to generate tail flicking, and aims at the low-adhesion road surface: the torque of the shaft end of the engine is specially processed, so that the torque of the front wheel end is reduced, and the slip probability of the front wheel end is reduced; the rear axle motor is specially processed, so that the torque output slope is reduced, and the stability of a rear wheel is ensured; the energy recovery strategy is optimized, when a low-adhesion road surface is detected, the energy recovery intensity is reduced, even the recovery is not carried out, and the vehicle instability caused by the sideslip of the vehicle due to excessive recovery is avoided.
(2) The control method of the hybrid vehicle with the low-attachment road surface integrates various driving working conditions to identify the current road surface condition, can help a driver to safely drive under the road conditions of ice, snow and the like, and greatly improves the driving safety in winter.
(3) The control method of the hybrid vehicle with the low-attachment road surface reduces the intervention frequency of an ESP system, protects the power elements of the vehicle and prolongs the service life of an electronic system.
(4) The control method of the hybrid vehicle with the low-attachment road surface is completely developed from a software level, the control strategy is written into a software program, and the performance can be optimized through real vehicle calibration, so that the method is simple and can save development cost.
Another object of the present invention is to propose a machine readable storage medium to at least partially solve the above technical problem.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a machine-readable storage medium having stored thereon instructions for causing a controller to execute the above-described hybrid vehicle control method for a low-adhesion road surface.
The machine-readable storage medium has the same advantages as the hybrid vehicle control method described above over the prior art, and is not described herein again.
Another object of the present invention is to propose a hybrid vehicle control system with low road surface adhesion to at least partially solve the above technical problem.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a low-road-attachment hybrid vehicle control system, for a P0+ P4 power configuration of a hybrid vehicle, in which a front axle power of the hybrid vehicle is derived from an engine and a rear axle power is derived from a rear axle motor in the P0+ P4 power configuration, the low-road-attachment hybrid vehicle control system comprising: the low-adhesion road surface identification module is used for identifying whether the current road surface is a low-adhesion road surface; and the control module is used for executing any one or more of the following sub-modules when the current road surface is the low-adhesion road surface:
an engine control submodule for adjusting an output torque of the engine to reduce a front wheel end torque of the hybrid vehicle;
the motor control submodule is used for adjusting the torque rising slope and the output torque of the rear axle motor so as to reduce the rear wheel end torque of the hybrid vehicle; and
and the braking energy recovery control submodule is used for reducing the intensity of braking energy recovery aiming at the hybrid vehicle or forbidding the braking energy recovery function of the hybrid vehicle.
Further, the low-adhesion road surface identification module includes: the starting road surface identification submodule is used for calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not if wheels slip in the process of starting the vehicle, when an opening signal of an accelerator pedal is in a corresponding preset range and the opening of a brake pedal is 0, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the count, otherwise, subtracting 1 from the count, and when the count value is greater than the preset count threshold value, judging that the current road surface is a low-attachment road surface; the braking road surface identification submodule is used for calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not if wheels are locked when a brake pedal opening signal is in a corresponding preset range and the accelerator pedal opening is 0 in the vehicle braking process, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the count, otherwise, subtracting 1 from the count, and when the count value is greater than the preset count threshold value, judging that the current road surface is a low-attachment road surface; the sliding road surface identification submodule is used for calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not when wheels are locked when the opening degree of a brake pedal is 0 and the opening degree of an accelerator pedal is 0 in the vehicle sliding process, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the counting, otherwise, subtracting 1 from the counting, and when the counting value is greater than the preset counting threshold value, judging that the current road surface is a low-attachment road surface; and the normal running road surface identification submodule is used for calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not if wheels are locked when the vehicle speed is greater than a preset vehicle speed threshold value, the vehicle turns, the opening degree of a brake pedal is 0 and the driver is judged to be on the accelerator pedal during the normal running process of the vehicle, if the slip rate is greater than the preset slip rate threshold value, the counting is increased by 1, otherwise, the counting is decreased by 1, and when the counting value is greater than the preset counting threshold value, the current road surface is judged to be a low-attachment road surface.
Further, the engine control sub-module for adjusting the output torque of the engine includes: and adjusting the pedal diagram curve of the engine to ensure that the engine output torque of the low-attachment road surface is lower than that of the common road surface under the same accelerator pedal opening.
Further, the motor control submodule for adjusting the torque rising slope and the output torque of the rear axle motor includes: when the steering wheel rotating angle of the hybrid vehicle is larger than a corresponding set value and the steering wheel rotating speed of the hybrid vehicle is smaller than the corresponding set value, judging that the current low-adhesion road surface is a low-adhesion turning road surface, slowing down the torque rising slope of the rear axle motor aiming at the low-adhesion turning road surface, and reducing the output torque of the rear axle motor.
Further, the control module is a hybrid vehicle controller HCU of a hybrid vehicle, and the low-attachment road surface identification module is integrated in the HCU.
Compared with the prior art, the hybrid vehicle control system with the low-attachment road surface has the same advantages as the hybrid vehicle control method, and the detailed description is omitted.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a conventional vehicle force diagram;
FIG. 2 is a schematic flow chart of a control method for a low-adhesion hybrid vehicle according to an embodiment of the present invention;
FIG. 3 is a logic diagram for low adhesion road surface identification in a preferred embodiment of the present invention;
FIG. 4 is a flow chart illustrating the application of a first low-profile identification policy according to an embodiment of the present invention;
FIG. 5 is a flow chart illustrating the application of a second low-profile identification policy according to an embodiment of the present invention;
FIG. 6 is a flow chart illustrating the application of a third low-profile identification strategy according to an embodiment of the present invention;
FIG. 7 is a flow chart illustrating the application of a fourth low-profile identification strategy according to an embodiment of the present invention;
FIG. 8 is a schematic illustration of a base torque distribution;
FIG. 9 is a schematic illustration of adjusting the nodal map curve in a preferred embodiment of the present invention; and
fig. 10 is a schematic structural diagram of a low-attachment-surface hybrid vehicle control system according to an embodiment of the present invention.
Description of reference numerals:
1010. low-attachment road surface identification module 1020 and control module
1011. Starting road surface identification submodule 1012 and braking road surface identification submodule
1013. Sliding road surface identification submodule 1014 and normal driving road surface identification submodule
1021. Engine control submodule 1022 and motor control submodule
1023. Braking energy recovery control submodule
Detailed Description
In addition, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.
In addition, the method and the system mentioned in the embodiment of the invention need to be understood in combination with the whole vehicle running power equation of the vehicle, and the whole vehicle running power equation is explained first.
Fig. 1 is a conventional vehicle force diagram, wherein V denotes vehicle speed and shows the vehicle direction of travel, Fn is the support force provided by the ramp, F is the total resistance, and the meaning of other technical parameters can be referred to below. When the vehicle runs on a certain slope, the rolling resistance F from the ground is overcomefAnd air resistance F from the airwIn addition, the gradient resistance F must be overcomeiThe vehicle is required to overcome the acceleration resistance F during accelerationjThus, the total resistance to vehicle travel is
∑F＝Ff+Fw+Fi+Fj (1)
Wherein:
Ft-total driving force, sum of front axle driving force and rear axle driving force, i.e. Ft＝Ft1+Ft2；
FiRamp resistance, the component of the vehicle weight along the ramp being manifested as the vehicleGradient resistance, G being the gravity acting on the vehicle, G ═ mg, m being the vehicle mass, G being the acceleration of gravity, α being the gradient.
FjThe rolling resistance is that the gravity component of the vehicle vertical to the road surface of the ramp is Gcos alpha, and the friction coefficient of the road surface is mu.
According to the standard Pacejka magic equation, the equation for the longitudinal friction coefficient μ of the tire in the Pacejka model is:
μ(λ,Vx)＝a(1-e-bλ-cλ) (2)
where λ is the tire slip ratio, and the coefficient a, the coefficient b, and the coefficient c are varied according to the current road surface on which the vehicle is running.
FwAir resistance, in the driving range of the vehicle, the air resistance of the vehicle is
Figure BDA0001712522260000091
In the formula, CDIs the air resistance coefficient, rho is the air density, A is the windward area, urAs a relative speed, in the absence of wind, i.e. the running speed V of the vehiclex。
FjThe acceleration resistance is needed to overcome the inertia force of the mass during acceleration movement during acceleration running,
Figure BDA0001712522260000092
where δ is a vehicle rotating mass conversion factor, which is related to the moment of inertia of the flywheel, the moment of inertia of the wheels, and the gear ratio of the drive train.
In summary, for the whole vehicle determined by each technical parameter, when the whole vehicle travels at a certain speed on a certain slope, the resistance applied thereto can be calculated by the vehicle basic theory, and the details thereof will not be described below. To ensure normal running of the vehicle, the front driving wheel traction force Ft1Is composed of
Figure BDA0001712522260000093
Wherein n is the BSG belt transmission ratio, igTo the transmission ratio of the variator, i0Is the transmission ratio of the main reducer, etaTRepresenting the mechanical efficiency of the drive train, r being the wheel radius, TEngTrq+TBSGTrqIs the total torque T of the front shaft endFAWherein T isEngTrqFor engine output torque, TBSGTrqTo BSG output torque, it can be understood with reference to the background section.
Rear drive wheel traction Ft2Is composed of
Figure BDA0001712522260000094
In the formula, TMotorFor output of torque, i, of rear-axle motor1Is the transmission ratio of the rear axle motor, etaTMTo drive mechanical efficiency.
On the basis of the above, the present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
Fig. 2 is a flowchart illustrating a hybrid vehicle control method for a low-road-surface area according to an embodiment of the present invention, wherein the hybrid vehicle control method is configured for a P0+ P4 power configuration of the hybrid vehicle.
In connection with the background section, it is known that in the P0+ P4 power configuration, the front axle power of the hybrid vehicle is derived from the engine and the rear axle power is derived from the rear axle motor. Specifically, the engine is responsible for controlling the front axle drive, the torque value is the sum of the engine torque and the BSG torque-speed ratio, the electric machine is responsible for the rear axle drive, and the rear axle torque is derived from the 350V high voltage battery and the electric machine. The torque distribution strategy and the torque framework of the front axle and the rear axle can be arranged in the HCU, and the HCU respectively controls the torque of the front axle and the rear axle according to the vehicle speed, the gradient, the steering wheel angle, the static axle load, the SOC (State of Charge) of the high-voltage battery and other variables. Meanwhile, when the vehicle is unstable (such as wheel slip, excessive deceleration, understeer/oversteer, etc.), the ESP system intervenes in the control to perform torque interference or brake force distribution on the front and rear axles, respectively. The intervention control of the ESP mainly comprises the following steps: the ESP system can assist a driver to stabilize a vehicle under working conditions of emergency braking, violent acceleration, high-speed operation stability and the like, and the ESP system mainly judges the vehicle condition according to the vehicle slip rate and the wheel deceleration. The slip ratio- ∞ < lambda of the vehicle is less than or equal to 100 percent, and the calculation formula is as follows:
Figure BDA0001712522260000101
in the formula, VxFor vehicle speed, r is the rolling radius of the tire, and ω is the wheel speed. When λ changes from 0 to 100%, the wheel changes from the free rolling state to the wheel locking state, and when λ changes from 0 to ∞, the wheel changes from the free rolling state to the wheel slipping state.
In addition, when the vehicle runs on a road surface, the tire is subjected to frictional resistance of the ground, and the force can be decomposed into a longitudinal force and a lateral force, and the two forces cancel each other. Longitudinal forces affect the steering ability of the vehicle and lateral forces affect the stability ability of the vehicle. Under the influence of the characteristics of the tire, the lateral force and the slip ratio of the tire are in a linear relationship within a certain range, and when the slip ratio exceeds a certain range (about 20%), the lateral force and the slip ratio are in a nonlinear relationship, and the stability control capability is reduced, so that the ESP generally controls the slip ratio of the driving wheel to be between 15% and 20%, and not only is certain steering capability ensured, but also the stability of the automobile is ensured.
One of the purposes of the hybrid vehicle control method of the embodiment of the invention is to reduce the intervention of the ESP system.
As shown in fig. 2, the method for controlling a hybrid vehicle with a low attachment road surface may include the steps of:
and step S110, identifying whether the current road surface is a low-adhesion road surface.
FIG. 3 is a logic diagram for low adhesion road surface identification in a preferred embodiment of the present invention. As shown in fig. 3, in the preferred embodiment, four strategies may be adopted for low-attachment road surface identification, each strategy may be individually determined or may be determined in combination, and when any one strategy identifies that the current road surface is a low-attachment road surface, the current road surface is considered to be a low-attachment road surface. These four strategies are specifically as follows:
1) first low-annex identification policy: for a vehicle launch process.
The basic principle of the strategy is as follows: in the starting process of the vehicle, when the opening signal of the accelerator pedal is in a corresponding preset range and the opening of the brake pedal is 0, if the wheel slips, calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the count, otherwise, subtracting 1 from the count, and when the count value is greater than the preset count threshold value, judging that the current road surface is a low-attachment road surface.
Fig. 4 is a schematic flow chart illustrating an application process of a first low-profile identification policy according to an embodiment of the present invention. As shown in fig. 4, on the basis of the basic principle, the road surface identification by using the first low-adhesion identification strategy may specifically include the following steps:
and step S410, judging whether the opening degree of the accelerator pedal is in a range formed by a threshold value TBD1 to a threshold value TBD2, if so, executing step S420, and otherwise, judging the opening degree of the accelerator pedal again.
In the actual vehicle starting process, a driver steps on an accelerator pedal, the HCU can judge the depth of the driver stepping on the accelerator pedal by receiving an opening signal of the accelerator pedal, and if the driver steps on the accelerator pedal less and wheels skid, the road surface is probably a low-attachment road surface and can be judged next step.
Among them, to satisfy the condition that the driver's depression of the accelerator pedal is relatively small, TBD1 and TBD2 need to be relatively set to small values, and note that TBD1< TBD 2.
In step S420, it is determined whether the opening of the brake pedal is 0, if so, step S430 is executed, otherwise, step S410 is returned to.
Step S430, calculating FL/FR/RL/RR slip ratio.
Where FL denotes a front left wheel, FR denotes a front right wheel, RL denotes a rear left wheel, and RR denotes a rear right wheel.
Specifically, the FL/FR/RL/RR slip ratio can be calculated by the above formula (7) according to the FL/FR/RL/RR wheel Speed signal wss (wheel Speed sensor) and the vehicle Speed signal vso (vehicle Speed output) collected by the vehicle wheel Speed sensor, and the calculation method is conventional and will not be described herein.
In addition, it is noted that, in calculating the FL/FR/RL/RR slip ratio, it has been determined that the wheel is slipping based on the slip ratio.
Step S440, determining whether the slip ratio is greater than a threshold TBD3, if so, executing step S450, otherwise, subtracting 1 from the count, and returning to step S410.
TBD3 is a threshold value corresponding to the slip ratio.
Step S450, count plus 1.
Here, the counting function may be implemented by configuring a conventional counter in the HCU.
In step S460, it is determined whether the count value is greater than the threshold TBD4, if so, step S470 is executed, otherwise, step S410 is returned to.
In step S470, it is determined that the road surface is a low adhesion road surface.
Therefore, the low-adhesion road surface judgment for the vehicle starting process is realized.
2) Second low-annex identification policy: for a vehicle braking process.
The basic principle of the strategy is as follows: in the vehicle braking process, when a brake pedal opening signal is in a corresponding preset range and the accelerator pedal opening is 0, if wheels are locked, calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the count, otherwise, subtracting 1 from the count, and when the count value is greater than the preset count threshold value, judging that the current road surface is a low-adhesion road surface.
Fig. 5 is a schematic flow chart illustrating an application process of a second low-profile identification policy according to an embodiment of the present invention. As shown in fig. 5, on the basis of the above basic principle, the road surface identification using the second low-adhesion identification strategy may specifically include the following steps:
and step S510, judging whether the opening degree of the accelerator pedal is 0, if so, executing step S520, and otherwise, judging the opening degree of the accelerator pedal again.
And step S520, judging whether the opening degree of the brake pedal is in the range formed by the threshold TBD1 to the threshold TBD2, if so, executing step S5300, otherwise, returning to step S510.
In the actual vehicle braking process, a driver steps on a brake pedal, the HCU can judge the depth of the driver for stepping on the brake pedal by receiving a brake pedal opening degree signal, and if the driver steps on the accelerator pedal less and wheels are locked, the road surface is probably a low-adhesion road surface, and the next judgment can be carried out.
Among them, to satisfy the condition that the driver's depression of the accelerator pedal is relatively small, TBD1 and TBD2 need to be relatively set to small values, note that TBD1< TBD2, and TBD1 may be 0.
In step S530, FL/FR/RL/RR slip ratio is calculated.
In step S540, it is determined whether the slip ratio is greater than the threshold TBD3, if so, step 5450 is executed, otherwise, the count is decremented by 1, and the process returns to step S510.
In step S550, the count is incremented by 1.
In step S560, it is determined whether the count value is greater than the threshold TBD4, if so, step S570 is executed, otherwise, step S510 is returned to.
In step S570, it is determined that the road surface is a low adhesion road surface.
Accordingly, low-adhesion road surface judgment for the vehicle braking process is realized. In addition, the implementation details of steps S530 to S570 are the same as the first low-profile identification policy, and are not described herein again.
3) Third low-annex identification policy: for a vehicle coasting procedure.
The basic principle of the strategy is as follows: in the vehicle sliding process, when the opening degree of a brake pedal is 0 and the opening degree of an accelerator pedal is 0, if wheels are locked, calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the count, otherwise, subtracting 1 from the count, and when the count value is greater than the preset count threshold value, judging that the current road surface is a low-adhesion road surface.
Fig. 6 is a schematic flow chart illustrating an application process of a third low-profile identification policy according to an embodiment of the present invention. As shown in fig. 6, on the basis of the above basic principle, the road surface identification using the third low-adhesion identification strategy may specifically include the following steps:
step S610, determining whether the accelerator pedal opening and the brake pedal opening are both 0, if yes, performing step S620, otherwise, re-determining.
In the actual process of vehicle sliding, a driver does not step on an accelerator pedal and a brake pedal, and the opening degree signals of the accelerator pedal and the brake pedal sent by the travel sensors of the accelerator pedal and the brake pedal of the HCU judge that the vehicle is in a sliding state at the moment, if wheels are locked, the road surface is probably a low-adhesion road surface, and the next judgment can be carried out.
In step S620, the FL/FR/RL/RR slip ratio is calculated.
In step S630, it is determined whether the slip ratio is greater than the threshold TBD3, if so, step 5640 is executed, otherwise, the count is decremented by 1, and the process returns to step S610.
In step S640, the count is incremented by 1.
In step S650, it is determined whether the count value is greater than the threshold TBD4, if so, step S660 is executed, otherwise, step S610 is returned to.
In step S660, it is determined that the road surface is a low adhesion road surface.
Accordingly, the low-adhesion road surface judgment for the vehicle sliding process is realized. In addition, the implementation details of steps S620 to S660 are the same as the first low-profile identification policy, and are not described herein again.
4) Fourth low-annex identification policy: aiming at the normal running process of the vehicle.
The basic principle of the strategy is as follows: in the normal running process of the vehicle, when the vehicle speed is greater than a preset vehicle speed threshold value, the vehicle turns, the opening degree of a brake pedal is 0, and a driver is judged to be on the accelerator pedal, if wheels are locked, the slip rate of the hybrid vehicle is calculated, counting is carried out according to the condition that whether the slip rate is greater than the preset slip rate threshold value, if the slip rate is greater than the preset slip rate threshold value, the counting is increased by 1, otherwise, the counting is decreased by 1, and when the counting value is greater than the preset counting threshold value, the current road surface is judged to be a low-attachment road surface.
Fig. 7 is a schematic flow chart of the application of the fourth low-profile identification policy according to the embodiment of the present invention. As shown in fig. 7, on the basis of the above basic principle, the road surface identification using the fourth low-adhesion identification strategy may specifically include the following steps:
step S710, determining whether the vehicle speed is within the corresponding threshold value TBD1, if so, performing step S720, otherwise, determining again.
In step S720, it is determined whether the opening of the brake pedal is 0, if so, step S730 is executed, otherwise, step S710 is returned to.
Step S730, determining whether the steering angle of the vehicle is greater than a corresponding threshold value TBD2, if so, executing step S740, otherwise, returning to step S710.
Wherein, TBD2 is greater than 0, and if the steering angle is greater than TBD2, the vehicle is turning.
In addition, when the vehicle turns, the driver releases the accelerator pedal, the HCU judges that the accelerator pedal is being released through the accelerator pedal stroke sensor, if wheels are locked, the road surface is likely to be a low-adhesion road surface, and the next judgment can be carried out.
Step S740, calculating FL/FR/RL/RR slip ratio.
In step S750, it is determined whether the slip ratio is greater than the threshold TBD3, if yes, step 5760 is executed, otherwise, the count is decremented by 1, and the process returns to step S610.
In step S760, the count is incremented by 1.
In step S770, it is determined whether the count value is greater than the threshold TBD4, if so, step S780 is executed, otherwise, step S710 is returned to.
In step S780, it is determined that the road surface is a low adhesion road surface.
Accordingly, the low-adhesion road surface judgment for the normal running process of the vehicle is realized. In addition, the implementation details of steps S740 to S780 are the same as the first low-profile identification policy, and are not described herein again.
Step S120, when the current road surface is the low-adhesion road surface, executing any one or more of the following: step S121 of adjusting an output torque of the engine to reduce a front wheel end torque of the hybrid vehicle; step S122, adjusting the torque rising slope and the output torque of the rear axle motor to reduce the rear wheel end torque of the hybrid vehicle; and a step S123 of reducing the intensity of the braking energy recovery for the hybrid vehicle or prohibiting the braking energy recovery function of the hybrid vehicle.
During the daily running of the vehicle, the HCU adopts a table look-up form to determine the basic front-rear axle torque distribution ratio of the vehicle according to an accelerator pedal, a steering wheel angle, a vehicle speed, a gradient and an SOC. Fig. 8 is a schematic diagram of the basic torque distribution, and referring to fig. 8, it can be seen that various operating conditions such as acceleration, climbing, turning, high/low battery power, and the like can be considered in the basic torque distribution. The embodiment of the present invention adjusts the basic torque distribution shown in fig. 8 through the above steps S121 to S123 to reduce the wheel-end torque and reduce the wheel slip tendency.
In a preferred embodiment, the adjusting the output torque of the engine in step S121 may include: and adjusting the pedal map curve of the engine so that the engine output torque of the low-attachment road surface is lower than that of the common road surface under the same accelerator pedal opening.
Specifically, FIG. 9 is a schematic diagram of adjusting the nodal map curve in a preferred embodiment of the present invention. As shown in fig. 9, the torque is "scaled" on the basis of the standard curve for the ordinary road surface, that is, the engine output torque for the low-attachment road surface is lower at the same accelerator pedal opening degree, which is obtained from the formula (5), and the front wheel end torque is reduced.
In a preferred embodiment, the adjusting the torque rising slope and the output torque of the rear axle motor in step S122 may include: if the steering wheel rotating angle of the hybrid vehicle is larger than the corresponding set value and the steering wheel rotating speed of the hybrid vehicle is smaller than the corresponding set value, judging that the current low-adhesion road surface is a low-adhesion turning road surface, slowing down the torque rising slope of the rear axle motor aiming at the low-adhesion turning road surface, and reducing the output torque of the rear axle motor.
Specifically, according to the basic torque distribution principle of fig. 8, when a low-adhesion road surface is detected, if the steering wheel angle is greater than a certain value and the steering wheel rotation speed is less than or equal to a certain value, it is determined that the road surface is the low-adhesion road surface, the torque rising slope of the rear axle motor is adjusted, the output torque of the rear axle motor is reduced, the rear wheel end torque is reduced according to the formula (6), and the low-adhesion "tail flick" condition is improved.
Here, for a hybrid vehicle, energy recovery may be divided into coasting energy recovery and braking energy recovery. In the process of sliding energy recovery, a brake pedal and an accelerator pedal are not stepped, the rotating speed of wheels is larger than the rotating speed of a rear axle motor at the moment, namely the rear axle motor is in a dragging state, and the HCU converts the mechanical energy generated by the parts into electric energy to be stored in a battery at the moment. When energy recovery is carried out on a low-road-attachment condition, wheels are locked more easily, an ABS (Antilock Brake System) is involved more easily to relieve the locking condition of the wheels, and when the locking is released, energy recovery continues, locking control can be carried out repeatedly, and the stability of a vehicle is not facilitated.
Therefore, for reducing the intensity of the braking energy recovery for the hybrid vehicle or prohibiting the braking energy recovery function of the hybrid vehicle in step S123, it may include: when the road surface with low adhesion is detected, the HCU energy recovery function is quitted, the rear axle motor is only driven, the power generation function is not carried out when the dragging occurs, and the HCU reactivates the energy recovery function activation position until the road surface with low adhesion is judged to be not.
In summary, the hybrid vehicle control method with low adhesion road surface according to the embodiment of the present invention has the following advantages:
1) the method is used for identifying the low-adhesion road surface which is easy to generate tail flicking, and aiming at the low-adhesion road surface: the torque of the shaft end of the engine is specially processed, so that the torque of the front wheel end is reduced, and the slip probability of the front wheel end is reduced; the rear axle motor is specially processed, so that the torque output slope is reduced, and the stability of a rear wheel is ensured; the energy recovery strategy is optimized, when a low-adhesion road surface is detected, the energy recovery intensity is reduced, even the recovery is not carried out, and the vehicle instability caused by the vehicle sideslip due to excessive recovery is avoided.
2) The road condition of the current road is identified by integrating various driving conditions, so that a driver can be helped to safely drive under the road conditions of ice, snow and the like, and the driving safety in winter is greatly improved.
3) The intervention frequency of an ESP system is reduced, the power elements of the vehicle are protected, and the service life of an electronic system is prolonged.
4) The method provided by the embodiment of the invention is completely developed from a software level, the control strategy is written into a software program, and the performance can be optimized through real vehicle calibration, so that the method is simple and can save the development cost.
It is pointed out above that the method provided by the embodiments of the present invention can be completely developed from a software level, and the control policy is written into a software program. Based on the characteristic, the embodiment of the invention also provides a machine-readable storage medium, which stores instructions for causing a controller to execute the low-attachment-surface hybrid vehicle control method described in the above embodiment.
Based on the same inventive idea as the hybrid vehicle control method of the low-attachment road surface, the embodiment of the invention also provides a hybrid vehicle control system of the low-attachment road surface. Fig. 10 is a schematic structural diagram of a low-road-attachment hybrid vehicle control system according to an embodiment of the present invention, which is directed to a P0+ P4 power configuration of a hybrid vehicle in which the front-axle power of the hybrid vehicle is derived from an engine and the rear-axle power is derived from a rear-axle motor, and a P0+ P4 power configuration.
As shown in fig. 10, the hybrid vehicle control system may include: the low-adhesion road surface identification module 1010 is used for identifying whether the current road surface is a low-adhesion road surface; and a control module 1020 for executing any one or more of the following sub-modules when the current road surface is the low-adhesion road surface: an engine control submodule 1021 for adjusting an output torque of the engine to reduce a front wheel end torque of the hybrid vehicle; the motor control submodule 1022 is configured to adjust a torque rising slope and an output torque of the rear axle motor to reduce a rear wheel end torque of the hybrid vehicle; and a braking energy recovery control sub-module 1023 for reducing the intensity of braking energy recovery for the hybrid vehicle or prohibiting a braking energy recovery function of the hybrid vehicle.
In a preferred embodiment, the low-adhesion road surface identification module 1010 may include:
the starting road surface identification submodule 1011 is configured to, in a vehicle starting process, when an accelerator pedal opening degree signal is within a corresponding preset range and a brake pedal opening degree is 0, if a wheel slips, calculate a slip rate of the hybrid vehicle and count according to a condition that whether the slip rate is greater than a preset slip rate threshold value, if the slip rate is greater than the preset slip rate threshold value, add 1 to the count, otherwise, subtract 1 from the count, and when the count value is greater than the preset count threshold value, determine that the current road surface is a low-attachment road surface.
And the braking road surface identification submodule 1012 is used for calculating the slip ratio of the hybrid vehicle and counting according to the condition that whether the slip ratio is greater than a preset slip ratio threshold value or not if the wheels are locked when a brake pedal opening signal is in a corresponding preset range and the accelerator pedal opening is 0 in the vehicle braking process, adding 1 to the count if the slip ratio is greater than the preset slip ratio threshold value, and subtracting 1 from the count if the slip ratio is not greater than the preset slip ratio threshold value, and judging that the current road surface is a low-attachment road surface when the count value is greater than the preset count threshold value.
The sliding road surface identification submodule 1013 is used for calculating the slip rate of the hybrid vehicle and counting according to the situation that whether the slip rate is greater than a preset slip rate threshold value or not when wheels are locked when the opening degree of a brake pedal is 0 and the opening degree of an accelerator pedal is 0 in the vehicle sliding process, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the counting, otherwise, subtracting 1 from the counting, and when the counting value is greater than the preset counting threshold value, judging that the current road surface is a low-attachment road surface.
And the normal running road surface identification submodule 1014 is used for calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not if wheels are locked when the vehicle speed is greater than the preset vehicle speed threshold value, the vehicle turns, the opening degree of a brake pedal is 0 and the driver is judged to be on the accelerator pedal during the normal running process of the vehicle, adding 1 to the count if the slip rate is greater than the preset slip rate threshold value, otherwise subtracting 1 from the count, and judging that the current road surface is the low-attachment road surface when the count value is greater than the preset count threshold value.
In a more preferred embodiment, the engine control submodule 1021 for adjusting the output torque of the engine comprises: and adjusting the pedal map curve of the engine so that the engine output torque of the low-attachment road surface is lower than that of the common road surface under the same accelerator pedal opening.
In a more preferred embodiment, the motor control sub-module 1022 for adjusting the torque rising slope and the output torque of the rear axle motor includes: when the steering wheel rotating angle of the hybrid vehicle is larger than a corresponding set value and the steering wheel rotating speed of the hybrid vehicle is smaller than the corresponding set value, judging that the current low-adhesion road surface is a low-adhesion turning road surface, slowing down the torque rising slope of the rear axle motor aiming at the low-adhesion turning road surface, and reducing the output torque of the rear axle motor.
In a more preferred embodiment, the control module 1020 is a hybrid vehicle controller HCU of a hybrid vehicle, and the low-attachment road surface identification module 1010 is integrated into the HCU. The low-attachment road surface identification module 1010 is also provided with a timer for realizing a timing function involved in road surface identification.
Other implementation details and effects of the hybrid vehicle control system with a low road surface according to the embodiment of the present invention are the same as or similar to those of the hybrid vehicle control method described above, and are not described herein again.
Those skilled in the art will understand that all or part of the steps in the method according to the above embodiments may be implemented by a program, which is stored in a storage medium and includes several instructions to enable a single chip, a chip, or a processor (processor) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (10)

1. A low-road-attachment hybrid vehicle control method, characterized by a P0+ P4 power configuration for a hybrid vehicle in which a front axle power of the hybrid vehicle is derived from an engine and a rear axle power is derived from a rear axle motor in the P0+ P4 power configuration, and comprising:
identifying whether the current road surface is a low-adhesion road surface; and
when the current road surface is the low-adhesion road surface, performing any one or more of the following:
adjusting an output torque of the engine to reduce a front wheel end torque of the hybrid vehicle;
adjusting the torque rising slope and the output torque of the rear axle motor to reduce the rear wheel end torque of the hybrid vehicle; and
reducing an intensity of braking energy recovery for the hybrid vehicle or prohibiting a braking energy recovery function of the hybrid vehicle.
2. The low-adhesion-road hybrid vehicle control method according to claim 1, wherein the identifying whether the current road surface is a low adhesion road surface includes:
in the starting process of the vehicle, when an opening signal of an accelerator pedal is in a corresponding preset range and the opening of a brake pedal is 0, if a wheel slips, calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the count, otherwise, subtracting 1 from the count, and when the count value is greater than the preset count threshold value, judging that the current road surface is a low-attachment road surface;
in the vehicle braking process, when a brake pedal opening signal is in a corresponding preset range and the accelerator pedal opening is 0, if wheels are locked, calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the counting, otherwise, subtracting 1 from the counting, and when the counting value is greater than the preset counting threshold value, judging that the current road surface is a low-attachment road surface;
in the vehicle sliding process, when the opening degree of a brake pedal is 0 and the opening degree of an accelerator pedal is 0, if wheels are locked, calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the count, otherwise, subtracting 1 from the count, and when the count value is greater than the preset count threshold value, judging that the current road surface is a low-attachment road surface; and
in the normal running process of the vehicle, when the vehicle speed is greater than a preset vehicle speed threshold value, the vehicle turns, the opening degree of a brake pedal is 0, and a driver is judged to be on the accelerator pedal, if wheels are locked, the slip rate of the hybrid vehicle is calculated, counting is carried out according to the condition that whether the slip rate is greater than the preset slip rate threshold value, if the slip rate is greater than the preset slip rate threshold value, the counting is increased by 1, otherwise, the counting is decreased by 1, and when the counting value is greater than the preset counting threshold value, the current road surface is judged to be a low-attachment road surface.
3. The low-adhesion hybrid vehicle control method according to claim 1, wherein the adjusting the output torque of the engine includes:
and adjusting the pedal diagram curve of the engine to ensure that the engine output torque of the low-attachment road surface is lower than that of the common road surface under the same accelerator pedal opening.
4. The method according to claim 1, wherein the adjusting the torque-up slope and the output torque of the rear axle motor includes:
if the steering wheel rotating angle of the hybrid vehicle is larger than the corresponding set value and the steering wheel rotating speed of the hybrid vehicle is smaller than the corresponding set value, judging that the current low-adhesion road surface is a low-adhesion turning road surface, slowing down the torque rising slope of the rear axle motor aiming at the low-adhesion turning road surface, and reducing the output torque of the rear axle motor.
5. A machine-readable storage medium having stored thereon instructions for causing a controller to execute the low-adhesion hybrid vehicle control method according to any one of claims 1 to 4.
6. A low-road-attachment hybrid vehicle control system, characterized in that the low-road-attachment hybrid vehicle control system is configured for a P0+ P4 power configuration of a hybrid vehicle, in the P0+ P4 power configuration, a front axle power of the hybrid vehicle is derived from an engine, a rear axle power is derived from a rear axle motor, and the low-road-attachment hybrid vehicle control system comprises:
the low-adhesion road surface identification module is used for identifying whether the current road surface is a low-adhesion road surface; and
the control module is used for executing any one or more of the following sub-modules when the current road surface is the low-adhesion road surface:
an engine control submodule for adjusting an output torque of the engine to reduce a front wheel end torque of the hybrid vehicle;
the motor control submodule is used for adjusting the torque rising slope and the output torque of the rear axle motor so as to reduce the rear wheel end torque of the hybrid vehicle; and
and the braking energy recovery control submodule is used for reducing the intensity of braking energy recovery aiming at the hybrid vehicle or forbidding the braking energy recovery function of the hybrid vehicle.
7. The low-adhesion hybrid vehicle control system according to claim 6, wherein the low-adhesion road surface recognition module includes:
the starting road surface identification submodule is used for calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not if wheels slip in the process of starting the vehicle, when an opening signal of an accelerator pedal is in a corresponding preset range and the opening of a brake pedal is 0, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the count, otherwise, subtracting 1 from the count, and when the count value is greater than the preset count threshold value, judging that the current road surface is a low-attachment road surface;
the braking road surface identification submodule is used for calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not if wheels are locked when a brake pedal opening signal is in a corresponding preset range and the accelerator pedal opening is 0 in the vehicle braking process, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the count, otherwise, subtracting 1 from the count, and when the count value is greater than the preset count threshold value, judging that the current road surface is a low-attachment road surface;
the sliding road surface identification submodule is used for calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not when wheels are locked when the opening degree of a brake pedal is 0 and the opening degree of an accelerator pedal is 0 in the vehicle sliding process, if the slip rate is greater than the preset slip rate threshold value, adding 1 to the counting, otherwise, subtracting 1 from the counting, and when the counting value is greater than the preset counting threshold value, judging that the current road surface is a low-attachment road surface; and
and the normal running road surface identification submodule is used for calculating the slip rate of the hybrid vehicle and counting according to the condition that whether the slip rate is greater than a preset slip rate threshold value or not if wheels are locked when the vehicle speed is greater than a preset vehicle speed threshold value, the vehicle turns, the opening degree of a brake pedal is 0 and the driver is judged to be on the accelerator pedal during the normal running process of the vehicle, adding 1 to the count if the slip rate is greater than the preset slip rate threshold value, otherwise subtracting 1 from the count, and judging that the current road surface is a low-attachment road surface when the count value is greater than the preset count threshold value.
8. A low-adhesion hybrid vehicle control system as claimed in claim 6, wherein the engine control sub-module for adjusting the output torque of the engine comprises:
and adjusting the pedal diagram curve of the engine to ensure that the engine output torque of the low-attachment road surface is lower than that of the common road surface under the same accelerator pedal opening.
9. The low-adhesion hybrid vehicle control system according to claim 6, wherein the motor control submodule for adjusting the torque rising slope and the output torque of the rear axle motor comprises:
when the steering wheel rotating angle of the hybrid vehicle is larger than a corresponding set value and the steering wheel rotating speed of the hybrid vehicle is smaller than the corresponding set value, judging that the current low-adhesion road surface is a low-adhesion turning road surface, slowing down the torque rising slope of the rear axle motor aiming at the low-adhesion turning road surface, and reducing the output torque of the rear axle motor.
10. The low-adhesion hybrid vehicle control system according to any one of claims 6 to 9, wherein the control module is a hybrid vehicle controller HCU of a hybrid vehicle, and the low-adhesion road surface recognition module is integrated in the HCU.
CN201810691141.0A 2018-06-28 2018-06-28 Hybrid vehicle control method and system with low-attachment road surface Pending CN110654370A (en)

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