CN113978261A - Electric vehicle crawling starting control method and device - Google Patents

Electric vehicle crawling starting control method and device Download PDF

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Publication number
CN113978261A
CN113978261A CN202111242123.2A CN202111242123A CN113978261A CN 113978261 A CN113978261 A CN 113978261A CN 202111242123 A CN202111242123 A CN 202111242123A CN 113978261 A CN113978261 A CN 113978261A
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output torque
overcoming
vehicle speed
resistance
torque
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CN113978261B (en
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陈宇
费晓翔
丁建民
唐杰
陈乐天
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Weichai Yangzhou Yaxing New Energy Commercial Vehicle Co ltd
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Weichai Yangzhou Yaxing New Energy Commercial Vehicle Co ltd
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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
    • B60L15/2063—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 for creeping
    • 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
    • B60L15/2072—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 for drive off
    • 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
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/42—Drive Train control parameters related to electric machines
    • B60L2240/423—Torque
    • 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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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

The invention belongs to the technical field of electric vehicles, and provides a creep start control method and device for an electric vehicle. The method comprises the following steps: after the crawling starts, S1, acquiring a required output torque based on the current torque and a preset vehicle speed-time curve; s2, acquiring the actual output torque and acceleration of the vehicle in the time period from the beginning of creeping to the current moment, and determining an actual resistance-overcoming torque-time curve; s3, acquiring the required output torque for overcoming the predicted resistance according to the actual resistance-overcoming torque-time curve; and S4, determining the required output torque or the required output torque for overcoming the predicted resistance to be executed by the vehicle according to preset judgment conditions. By adopting the technical scheme in the embodiment of the application, the uncertainty of unknown resistance can be reduced, the required output torque for executing the required output torque or overcoming the predicted resistance is judged by acquiring the required output torque for overcoming the predicted resistance, and the problem of vehicle speed error after the actual output torque is executed is optimized.

Description

Electric vehicle crawling starting control method and device
Technical Field
The invention relates to the technical field of electric vehicles, in particular to a creep starting control method and device for an electric vehicle.
Background
The electric vehicle is a vehicle which takes a vehicle-mounted power supply as power and drives wheels to run by a motor, and can solve the problem of tail gas emission caused by the traditional automobile fuel.
In the domestic market, some electric vehicle models of a plurality of manufacturers still do not have the function of crawling starting, the vehicle is electrified at high voltage, the gear of a gearbox is shifted to a forward gear or a backward gear, and the vehicle can be started and run only after an accelerator is stepped on after a brake pedal is released. Meanwhile, for a part of vehicle types with the crawling starting function, due to complex traffic and road environments, the vehicle may face frequent crawling starting in the driving process, and the control over stable torque is lacked in the crawling starting process, so that the crawling feeling is caused in the crawling process, the stability of the vehicle is not high in the driving process, and the driving comfort is reduced.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a crawling starting control method and a crawling starting control device for an electric vehicle, and aims to solve the problem that crawling control is unstable when the existing electric vehicle is started.
In a first aspect, the invention provides a creep start control method for an electric vehicle, comprising:
when the creep starts, the creep is started,
s1, acquiring a required output torque based on the current torque and a preset vehicle speed-time curve;
s2, acquiring the actual output torque and acceleration of the vehicle in the time period from the beginning of creeping to the current moment, and determining an actual resistance-overcoming torque-time curve;
s3, acquiring the required output torque for overcoming the predicted resistance according to the actual resistance-overcoming torque-time curve;
and S4, determining the required output torque or the required output torque for overcoming the predicted resistance to be executed by the vehicle according to preset judgment conditions.
According to the technical scheme, in order to enable the crawling starting process to accord with a preset vehicle speed-time curve, the crawling starting control method for the electric vehicle determines the executed output torque value by acquiring the required output torque and the predicted overcoming resistance output torque and according to the preset judgment condition. When a small error exists between the current running state of the vehicle and the preset vehicle speed-time curve, the required output torque obtained according to the current torque and the preset vehicle speed-time curve is continuously executed, and due to the uncertainty of unknown resistance, the required output torque overcoming the predicted resistance is the condition of overcoming the large error existing after the actual output torque is executed, so that the stability of the running process of the vehicle is ensured.
Optionally, step S1 includes:
determining the current vehicle running acceleration according to the preset vehicle speed-time curve;
determining the current rotating speed acceleration according to the current vehicle running acceleration; wherein the current rotational speed and the current vehicle running acceleration are positively correlated;
and determining the required output torque according to the current rotating speed acceleration.
Optionally, step S3 includes:
selecting data for acquiring the required output torque for overcoming the predicted resistance from the actual resistance-overcoming torque-time curve;
and judging the variability of the selected data, and calculating the required output torque for overcoming the predicted resistance.
Optionally, said selecting data for obtaining said demanded output torque to overcome predicted resistance in said actual output torque-time curve comprises:
if the data volume from the beginning of crawling to the current moment is less than N, determining the required output torque for overcoming the predicted resistance according to all the data from the beginning of crawling to the current moment;
and if the data volume from the beginning of crawling to the current moment is more than or equal to N, determining the required output torque for overcoming the predicted resistance according to the data at the current moment and N-1 data before the current moment.
Optionally, the variability of the selected data is judged by:
when the selected data accords with a monotonicity screening condition, the output torque of the predicted resistance overcoming requirement is equal to the actual resistance overcoming torque at the previous moment;
when the selected data meets the disorder change screening condition, the required output torque T for overcoming the predicted resistancen+1Obtained by the following method:
Figure BDA0003319886590000031
wherein k isiAs a weighting coefficient, T, related to the time differenceiAnd N is a preset acquired data volume for the actual overcome resistance torque at a certain moment in the actual overcome resistance torque-time curve.
Optionally, step S4 includes:
determining a predicted vehicle speed acceleration according to the required output torque, the actual overcome resistance torque and the required output torque for overcoming the predicted resistance;
and controlling the vehicle to execute the required output torque or the required output torque for overcoming the predicted resistance according to whether the vehicle speed acceleration meets the preset judgment condition.
Optionally, the preset determination condition is:
when the error between the predicted vehicle speed acceleration and the acceleration corresponding to the vehicle speed in the preset vehicle speed-time curve does not exceed a preset threshold value, controlling the vehicle to execute the required output torque;
and when the error between the predicted vehicle speed acceleration and the acceleration corresponding to the vehicle speed in the preset vehicle speed-time curve exceeds a preset threshold value, controlling the vehicle to execute the required output torque for overcoming the predicted resistance.
Optionally, step S4 further includes:
acquiring a current vehicle speed;
determining the next vehicle speed value after the current vehicle speed in the preset vehicle speed-time curve;
and determining the acceleration corresponding to the next vehicle speed value according to the preset vehicle speed-time curve, and determining the required target torque corresponding to the next vehicle speed value according to the acceleration corresponding to the next vehicle speed value.
Optionally, the method further comprises: and repeating the steps S1-S4 until the vehicle speed of the vehicle reaches a stable value in the preset vehicle speed-time curve.
In a second aspect, the invention provides a creep start control device for an electric vehicle, comprising:
the first acquisition module is used for acquiring the required output torque based on the current torque and a preset vehicle speed-time curve;
the second acquisition module is used for acquiring the actual output torque and the acceleration of the vehicle in the time period from the beginning of crawling to the current moment and determining an actual resistance-overcoming torque-time curve;
the resistance prediction module is used for acquiring the required output torque for overcoming the predicted resistance according to the torque-time curve of the actual overcome resistance;
and the judging module is used for determining that the vehicle executes the required output torque or the required output torque for overcoming the predicted resistance according to a preset judging condition.
Optionally, the first obtaining module is specifically configured to:
determining the current vehicle running acceleration according to the preset vehicle speed-time curve;
determining the current rotating speed acceleration according to the current vehicle running acceleration; wherein the current rotational speed and the current vehicle running acceleration are positively correlated;
and determining the required output torque according to the current rotating speed acceleration.
Optionally, the resistance prediction module is specifically configured to:
selecting data for obtaining the required output torque for overcoming the predicted resistance from the actual output torque-time curve;
and judging the variability of the selected data, and calculating the required output torque for overcoming the predicted resistance.
Optionally, the resistance prediction module is further specifically configured to:
if the data volume from the beginning of crawling to the current moment is less than N, determining the required output torque for overcoming the predicted resistance according to all the data from the beginning of crawling to the current moment;
and if the data volume from the beginning of crawling to the current moment is more than or equal to N, determining the required output torque for overcoming the predicted resistance according to the current moment and N data before the current moment.
Optionally, in the resistance prediction module, the variability of the selected data is judged by the following method:
when the selected data accords with a monotonicity screening condition, the output torque of the predicted resistance overcoming requirement is equal to the actual resistance overcoming torque at the previous moment;
when the selected data meets the disorder change screening condition, the required output torque T for overcoming the predicted resistancen+1Obtained by the following method:
Figure BDA0003319886590000051
wherein k isiAs a weighting coefficient, T, related to the time differenceiAnd N is a preset acquired data volume for the actual overcome resistance torque at a certain moment in the actual overcome resistance torque-time curve.
Optionally, the determining module is specifically configured to:
determining a predicted vehicle speed acceleration according to the required output torque, the actual overcome resistance torque and the required output torque for overcoming the predicted resistance;
and controlling the vehicle to execute the required output torque or the required output torque for overcoming the predicted resistance according to whether the vehicle speed acceleration meets the preset judgment condition.
Optionally, in the determining module, the preset determining condition is:
when the error between the predicted vehicle speed acceleration and the acceleration corresponding to the vehicle speed in the preset vehicle speed-time curve does not exceed a preset threshold value, controlling the vehicle to execute the required output torque;
and when the error between the predicted vehicle speed acceleration and the acceleration corresponding to the vehicle speed in the preset vehicle speed-time curve exceeds a preset threshold value, controlling the vehicle to execute the required output torque for overcoming the predicted resistance.
Optionally, the determining module is specifically further configured to:
acquiring a current vehicle speed;
determining the next vehicle speed value after the current vehicle speed in the preset vehicle speed-time curve;
and determining the acceleration corresponding to the next vehicle speed value according to the preset vehicle speed-time curve, and determining the required target torque corresponding to the next vehicle speed value according to the acceleration corresponding to the next vehicle speed value.
Optionally, the resistance prediction module and the determination module are further specifically configured to: and repeating the steps S1-S4 until the vehicle speed of the vehicle reaches a stable value in the preset vehicle speed-time curve.
In a third aspect, an embodiment of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of any one of the methods when executing the computer program.
In a fourth aspect, an embodiment of the invention provides a computer-readable storage medium having stored thereon computer program instructions which, when executed by a processor, implement the steps of any of the methods described above.
By adopting the technical scheme, the method has the following technical effects:
1) the invention provides a crawling starting control method for an electric vehicle, which is used for ensuring that a crawling starting process accords with a preset vehicle speed-time curve, acquiring a required output torque and a predicted overcoming resistance output torque, and determining an executed output torque value according to a preset judgment condition. When a small error exists between the current running state of the vehicle and the preset vehicle speed-time curve, the required output torque obtained according to the current torque and the preset vehicle speed-time curve is continuously executed, and due to the uncertainty of unknown resistance, the required output torque overcoming the predicted resistance is the condition of overcoming the large error existing after the actual output torque is executed, so that the stability of the running process of the vehicle is ensured.
2) The method of the invention determines the specific torque value to be executed according to the judgment condition for realizing the speed requirement set in the preset speed-time curve in the vehicle crawling starting process by respectively obtaining the required output torque in an ideal state (with constant resistance) and considering the required output torque for overcoming the predicted resistance under the condition of unknown resistance, so that the torque at the target moment is as consistent as possible with the actual driving condition of the crawling starting of the electric vehicle, and the stability and the safety of the crawling starting are improved.
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In order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description of the invention or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.
FIG. 1 is a flow chart illustrating a method for controlling a creep start of an electric vehicle according to an embodiment of the invention;
FIG. 2 is a schematic diagram illustrating a preset vehicle speed-time curve provided by an embodiment of the present invention;
FIG. 3 is a flowchart illustrating a creep start control method for an electric vehicle according to an embodiment of the present invention;
fig. 4 shows a block diagram of a creep start control device of an electric vehicle according to an embodiment of the invention;
fig. 5 shows a block diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.
It is to be noted that, unless otherwise specified, technical or scientific terms used herein shall have the ordinary meaning as understood by those skilled in the art to which the invention pertains.
When the electric vehicle runs, the biggest difference between the electric vehicle and the internal combustion engine vehicle is an electric driving and controlling system, wherein the electric driving and controlling system mainly converts electric energy provided by a power supply into mechanical energy. Further, by controlling the torque of the drive motor, the state control at the time of the vehicle creep start can be realized.
Fig. 1 shows a flowchart of a creep start control method for an electric vehicle according to a first embodiment of the present invention. As shown in fig. 1, a creep start control method according to an embodiment of the present invention includes:
when the creep starts, the creep is started,
and S1, acquiring the required output torque based on the current torque and the preset vehicle speed-time curve.
Specifically, as shown in fig. 2, the preset vehicle speed-time curve is a vehicle speed change curve manually set before the vehicle runs, and the preset vehicle speed-time curve includes a starting stage and a constant speed stage. And in the process from the starting stage to the constant speed stage, the speed of the vehicle gradually reaches a stable value from 0, and the stable value is set according to the running conditions of different vehicles. And determining the required output torque according to the acquired current torque. In one possible embodiment, the current torque is the acquired real-time output torque, data is acquired every 20ms, and the required output torque is acquired based on the current torque acquired at the current moment and a preset vehicle speed-time curve.
And S2, acquiring the actual output torque and acceleration of the vehicle in the time period from the beginning of creeping to the current moment, and determining an actual resistance-overcoming torque-time curve.
Specifically, from the start of creeping to the present time, in order to drive the vehicle to travel according to the preset vehicle speed-time curve, the actual output torque of the vehicle in the period from the start time to the present time is acquired, and the actual output torque-time curve is formed, so that step S3 is performed to acquire the required output torque to overcome the predicted resistance.
And S3, acquiring the required output torque for overcoming the predicted resistance according to the actual resistance-overcoming torque-time curve.
Specifically, the actual output torque-time curve acquired in step S2 is the actual torque output by the vehicle at each time according to the preset vehicle speed of the preset vehicle speed-time curve during the creep of the vehicle. However, during the vehicle creep, there are other resistance disturbances, so that the actual output torque conversion cannot meet the preset acceleration requirement. In this embodiment, the required output torque for overcoming the predicted resistance is obtained according to the actual output torque-time curve, and the output torque required for overcoming the resistance at the next time is predicted, so that the vehicle speed at the next time meets the vehicle speed requirement in the preset vehicle speed-time curve. In addition, the next time differs from the current time by 0.02 s.
And S4, determining the vehicle execution demand output torque or the demand output torque for overcoming the predicted resistance according to the preset judgment condition.
Specifically, whether the vehicle executes the required output torque or the required output torque to overcome the predicted resistance is determined according to a preset determination condition, the preset determination condition is related to the running acceleration of the vehicle, and the running acceleration of the vehicle and the actual output torque are positively related.
Optionally, step S1 includes:
determining the current vehicle running acceleration according to a preset vehicle speed-time curve;
determining the current rotating speed acceleration according to the current vehicle running acceleration; wherein the current rotating speed is positively correlated with the current vehicle running acceleration;
and determining the required output torque according to the current rotating speed acceleration.
Specifically, according to a preset vehicle speed-time curve, the current vehicle running acceleration is obtained by the following formula when the current time is reached:
Figure BDA0003319886590000081
as shown in fig. 2, k1 is a coefficient of a known rotation speed acceleration and a known vehicle speed acceleration, and n1 and n2 are a rotation speed, a rotation speed acceleration and a vehicle behavior corresponding to v1 and v2, respectivelyThe driving acceleration should be in positive correlation. After determining the current rotational speed acceleration, the output torque is demanded
Figure BDA0003319886590000082
Wherein, TnFor the current output torque, k2 is a coefficient related to speed and acceleration, and Te is other known drag torque. In one possible embodiment, Te comprises the torque required to overcome ground friction resistance.
In this step, the driving acceleration of the vehicle, corresponding to the rotational speed acceleration, may be obtained through a preset vehicle speed-time curve, so as to obtain a required output torque corresponding to the preset vehicle speed-time curve, where the required output torque is a required output torque at a target time in an ideal state, and a difference between t2 and t1 is 0.02 s. The preset vehicle speed-time curve provides a driving target vehicle speed for crawling starting, and meanwhile, driving acceleration can be obtained through the curve, so that required output torque is determined. The required output torque is a torque value required to realize a preset vehicle speed-time curve in an ideal state.
Alternatively, referring to fig. 3, step S3 includes:
s301, selecting data for acquiring required output torque for overcoming predicted resistance from an actual resistance-overcoming torque-time curve;
and S302, judging the variability of the selected data, and calculating the required output torque for overcoming the predicted resistance.
Specifically, due to the uncertainty of the resistance existing in the crawling process, the selected data may be monotonously increased or changed in a disordered manner along with the change of time. At this time, in order to overcome the change of the required output torque for overcoming the predicted resistance caused by the resistance change under the condition, the two conditions can be calculated according to the conditions, the effectiveness of the required output torque for overcoming the predicted resistance is improved, and the stability and the safety of the crawling process are ensured.
Optionally, step S301 includes:
if the data volume from the beginning of crawling to the current moment is less than N, determining the required output torque for overcoming the predicted resistance according to all the data from the beginning of crawling to the current moment;
and if the data volume from the beginning of crawling to the current moment is more than or equal to N, determining the required output torque for overcoming the predicted resistance according to the data at the current moment and N-1 data before the current moment.
Specifically, the required output torque to overcome the predicted resistance is the predicted value predicted from the actual output torque-time curve acquired in step S2, the data amount is insufficient at the beginning of creep, and the required output torque to overcome the predicted resistance is determined based on all the data from the beginning of creep to the current time.
When the data volume is larger than N, the data of the current moment and the nearest N-1 data before the current moment are taken to determine the required output torque for overcoming the predicted resistance, compared with the required output torque, the unknown resistance exists in the required output torque for overcoming the predicted resistance, which may be the resistance to the vehicle running state caused by the loss of each part in the vehicle crawling process, but the unknown resistance cannot be obtained through a specific measurement and other conventional manners.
Optionally, the variability of the selected data is judged by:
when the selected data accords with the monotonicity screening condition, the output torque required for overcoming the resistance is predicted to be equal to the actual torque for overcoming the resistance at the previous moment;
when the selected data meets the disorder change screening condition, the required output torque T for overcoming the predicted resistance is obtainedn+1Obtained by the following method:
Figure BDA0003319886590000101
wherein k isiAs a weighting coefficient, T, related to the time differenceiN is a preset acquired data amount for an actual overcome resistance torque at a certain moment in an actual overcome resistance torque-time curve.
In particular, overcomePredicted resistance demanded output torque Tn+1Is determined by obtaining a weighted average of the N data determined in step S301. T isiTime and Tn+1The difference of the time determines kiThe numerical value of (c). Because the closer the actual output torque at the target time is during creep, the greater the effect on the output torque at the target time. In one possible embodiment, when n<When N, T can be setnThe weighting coefficient at the moment, i.e. the current moment, is n, Tn-1The weighting coefficient at the moment is n-1, and so on to T1The weighting coefficient at the moment is 1; when N is greater than or equal to N, T can be setnThe weighting coefficient at the moment, i.e. the current moment, is N, Tn-1The weighting coefficient at the moment is N-1, and so on to Tn-N+1The weighting factor at a time is 1. In this embodiment, N is 50. In all examples shown and described herein, unless otherwise specified, any particular value should be construed as merely illustrative, and not restrictive, and thus other examples of example embodiments may have different values.
Obtaining the demanded output torque T to overcome the predicted resistance by weighted averagingn+1To make the required output torque T to overcome the predicted resistancen+1The actual output torque in the creeping process is met, and the running state is guaranteed to be in accordance with the conventional starting condition.
Optionally, the monotonicity screening conditions comprise:
obtaining a first torque difference value by respectively subtracting the second data to the nth data in the selected data from the previous data;
and if the number of the numerical values smaller than 0 in the torque difference is smaller than s, selecting data to meet the monotonicity screening condition.
Optionally, the disorder change screening conditions comprise:
determining the last x data from the selected data, and respectively subtracting the previous data from the second data to the x-th data in the x data to obtain a second torque difference value;
and if the number of the products of two adjacent numerical values in the second torque difference value is larger than 0 and smaller than z, selecting data to meet disorder change screening conditions.
Specifically, if the second data is different from the first data, obtaining a difference value to obtain a first and second torque difference value; the third data and the second data are subjected to difference to obtain a difference value, and a second torque difference value is obtained; … … and so on; and (4) subtracting the x-th data from the x-1 th data to obtain a difference value, so as to obtain an x-1 th torque difference value.
It should be noted that s and z can be set specifically according to actual situations, and both are set to be 2 in this embodiment. x is less than or equal to N, and x can be 20.
Optionally, step S4 includes:
determining a predicted vehicle speed acceleration according to the required output torque, the actual resistance overcoming torque and the required output torque for overcoming the predicted resistance;
and controlling the vehicle to execute the required output torque or the required output torque for overcoming the predicted resistance according to whether the vehicle speed acceleration meets the preset judgment condition.
Specifically, in this step, the required output torque is a torque to be executed at the next time calculated according to a preset vehicle speed-time curve, the required output torque to overcome the predicted resistance is a torque to be executed at the next time predicted from the actual output torque, and the required output torque to overcome the predicted resistance is different from the required output torque in consideration of an unknown resistance existing during creep of the vehicle. In the embodiment, since the torque, the speed and the acceleration are all positively correlated, the specific output torque for controlling the vehicle to execute can be determined by presetting the torque judgment condition or the judgment conditions such as the speed and the acceleration. The required output torque to overcome the predicted resistance includes a torque obtained from the acceleration and a predicted torque to overcome the resistance.
Optionally, the preset determination condition is:
when the error between the predicted vehicle speed acceleration and the acceleration corresponding to the vehicle speed in the preset vehicle speed-time curve does not exceed a preset threshold value, controlling the vehicle to execute the required output torque;
and when the error between the predicted vehicle speed acceleration and the acceleration corresponding to the vehicle speed in the preset vehicle speed-time curve exceeds a preset threshold value, controlling the vehicle to execute the required output torque for overcoming the predicted resistance.
Specifically, a preset judgment condition is set, the condition that the difference value is too large is screened, when the difference value does not exceed a certain threshold value, the vehicle executes the required output torque, otherwise, the preset overcoming resistance output torque is executed. In one possible embodiment, the difference is represented by vehicle speed acceleration, based on the formula ka-Tc-Tf, Tc being the demanded output torque, Tf being the demanded output torque to overcome the predicted resistance, a being the acceleration, and k being the correlation coefficient. And executing the output torque overcoming the resistance when the a exceeds a specific threshold, and executing the required output torque when the a does not exceed the specific threshold. In the present embodiment, one example sets the specific threshold value to 1. The specific threshold value is set specifically according to the running conditions of different vehicles.
By the aid of the preset judgment conditions, the output torque in the vehicle crawling process meets the driving requirement of a preset vehicle speed-time curve, validity of the output torque is guaranteed, the crawling process of the vehicle meets preset rules, and accordingly stability and safety of vehicle driving are guaranteed.
Optionally, step S4 further includes:
acquiring a current vehicle speed;
determining the next vehicle speed value after the current vehicle speed in a preset vehicle speed-time curve;
and determining the acceleration corresponding to the next vehicle speed value according to a preset vehicle speed-time curve, and determining the required target torque corresponding to the next vehicle speed value according to the acceleration corresponding to the next vehicle speed value.
Specifically, in the vehicle creep process, after the torque is output, the actual vehicle speed may not be the vehicle speed value relative to the corresponding time in the preset vehicle speed-time curve, and in order to accelerate the vehicle to the stable value in the preset vehicle speed-time curve in the stable state, the vehicle speed at the next time which should be reached at the next time should be searched according to the vehicle speed.
In one example, the vehicle speed at time t1 is v1 ', and the vehicle speed at time t2 is v2 according to the preset vehicle speed-time curve, however, since the vehicle speed v 1' at time t1 is already greater than v2, the vehicle speed at time t2 cannot be recovered to be v2 by output torque deceleration. In the present embodiment, the required output torque is obtained by finding the vehicle speed v closest to the vehicle speed v 1' in a preset vehicle speed-time curve. At this time, the vehicle speed v should be the first vehicle speed value greater than the vehicle speed v 1' in the preset vehicle speed-time curve, and the required target torque at the time point t2 is determined according to the preset vehicle speed curve v.
Optionally, the method further comprises: the steps S1-S4 are repeated until the vehicle speed at which the vehicle is running reaches a stable value in the preset vehicle speed-time curve.
Specifically, during the vehicle crawling process, the steps S1 to S4 are repeated continuously, so that the vehicle runs according to the preset vehicle speed-time curve, and when the crawling start is completed, the vehicle speed reaches the preset stable value, as shown in fig. 2, at this time, the output torque of the vehicle is kept at the first moment output torque value reaching the preset vehicle speed stable value.
In one embodiment, there is provided an electric vehicle creep start control apparatus 40 including:
a first obtaining module 401, configured to obtain a required output torque based on a current torque and a preset vehicle speed-time curve;
a second obtaining module 402, configured to obtain an actual output torque and an actual acceleration of the vehicle within a time period from a creep start to a current time, and determine an actual resistance-overcoming torque-time curve;
a resistance prediction module 403, configured to obtain a required output torque for overcoming the predicted resistance according to the torque-time curve of the actual overcome resistance;
a determining module 404, configured to determine, according to a preset determining condition, that the vehicle executes the required output torque or the required output torque to overcome the predicted resistance.
Optionally, the first obtaining module 401 is specifically configured to:
determining the current vehicle running acceleration according to the preset vehicle speed-time curve;
determining the current rotating speed acceleration according to the current vehicle running acceleration; wherein the current rotational speed and the current vehicle running acceleration are positively correlated;
and determining the required output torque according to the current rotating speed acceleration.
Optionally, the resistance prediction module 403 is specifically configured to:
selecting data for obtaining the required output torque for overcoming the predicted resistance from the actual output torque-time curve;
and judging the variability of the selected data, and calculating the required output torque for overcoming the predicted resistance.
Optionally, the resistance prediction module 403 is further configured to:
if the data volume from the beginning of crawling to the current moment is less than N, determining the required output torque for overcoming the predicted resistance according to all data from the beginning of crawling to the current moment;
and if the data volume from the beginning of crawling to the current moment is more than or equal to N, determining the required output torque for overcoming the predicted resistance according to the data at the current moment and N-1 data before the current moment.
Optionally, in the resistance prediction module 403, the variability of the selected data is determined by:
when the selected data accords with a monotonicity screening condition, the output torque of the predicted resistance overcoming requirement is equal to the actual resistance overcoming torque at the previous moment;
when the selected data meets the disorder change screening condition, the required output torque T for overcoming the predicted resistancen+1Obtained by the following method:
Figure BDA0003319886590000141
wherein k isiAs a weighting coefficient, T, related to the time differenceiAnd N is a preset acquired data volume for the actual overcome resistance torque at a certain moment in the actual overcome resistance torque-time curve.
Optionally, the determining module 404 is specifically configured to:
determining a predicted vehicle speed acceleration according to the required output torque, the actual overcome resistance torque and the required output torque for overcoming the predicted resistance;
and controlling the vehicle to execute the required output torque or the required output torque for overcoming the predicted resistance according to whether the vehicle speed acceleration meets the preset judgment condition.
Optionally, in the determining module 404, the preset determining condition is:
when the error between the predicted vehicle speed acceleration and the acceleration corresponding to the vehicle speed in the preset vehicle speed-time curve does not exceed a preset threshold value, controlling the vehicle to execute the required output torque;
and when the error between the predicted vehicle speed acceleration and the acceleration corresponding to the vehicle speed in the preset vehicle speed-time curve exceeds a preset threshold value, controlling the vehicle to execute the required output torque for overcoming the predicted resistance.
Optionally, the determining module 404 is further specifically configured to:
acquiring a current vehicle speed;
determining the next vehicle speed value after the current vehicle speed in the preset vehicle speed-time curve;
and determining the acceleration corresponding to the next vehicle speed value according to the preset vehicle speed-time curve, and determining the required target torque corresponding to the next vehicle speed value according to the acceleration corresponding to the next vehicle speed value.
Optionally, the resistance prediction module and the determination module are further specifically configured to: and repeating the steps S1-S4 until the vehicle speed of the vehicle reaches a stable value in the preset vehicle speed-time curve.
The electric vehicle crawling start control device 40 provided in the embodiment of the present application and the electric vehicle crawling start control method adopt the same inventive concept, and can obtain the same beneficial effects, and those skilled in the art can clearly understand that for convenience and simplicity of description, the specific working processes of the system, the device and the unit described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
Based on the same inventive concept as the method for controlling the creep start of the electric vehicle, the embodiment of the present application further provides an electronic device 50, as shown in fig. 5, the electronic device 50 may include a processor 501 and a memory 502.
The Processor 501 may be a general-purpose Processor, such as a Central Processing Unit (CPU), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, a discrete Gate or transistor logic device, or a discrete hardware component, which may implement or execute the methods, steps, and logic blocks disclosed in the embodiments of the present Application. A general purpose processor may be a microprocessor or any conventional processor or the like. The steps of a method disclosed in connection with the embodiments of the present application may be directly implemented by a hardware processor, or may be implemented by a combination of hardware and software modules in a processor.
Memory 502, which is a non-volatile computer-readable storage medium, may be used to store non-volatile software programs, non-volatile computer-executable programs, and modules. The Memory may include at least one type of storage medium, and may include, for example, a flash Memory, a hard disk, a multimedia card, a card-type Memory, a Random Access Memory (RAM), a Static Random Access Memory (SRAM), a Programmable Read Only Memory (PROM), a Read Only Memory (ROM), a charged Erasable Programmable Read Only Memory (EEPROM), a magnetic Memory, a magnetic disk, an optical disk, and so on. The memory is any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer, but is not limited to such. The memory 502 in the embodiments of the present application may also be circuitry or any other device capable of performing a storage function for storing program instructions and/or data.
Those of ordinary skill in the art will understand that: all or part of the steps for implementing the method embodiments may be implemented by hardware related to program instructions, and the program may be stored in a computer readable storage medium, and when executed, the program performs the steps including the method embodiments; the computer storage media may be any available media or data storage device that can be accessed by a computer, including but not limited to: various media that can store program codes include a removable Memory device, a Random Access Memory (RAM), a magnetic Memory (e.g., a flexible disk, a hard disk, a magnetic tape, a magneto-optical disk (MO), etc.), an optical Memory (e.g., a CD, a DVD, a BD, an HVD, etc.), and a semiconductor Memory (e.g., a ROM, an EPROM, an EEPROM, a nonvolatile Memory (NAND FLASH), a Solid State Disk (SSD)).
Alternatively, the integrated units described above in the present application may be stored in a computer-readable storage medium if they are implemented in the form of software functional modules and sold or used as independent products. Based on such understanding, the technical solutions of the embodiments of the present application may be essentially implemented or portions thereof contributing to the prior art may be embodied in the form of a software product stored in a storage medium, and including several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: various media that can store program codes include a removable Memory device, a Random Access Memory (RAM), a magnetic Memory (e.g., a flexible disk, a hard disk, a magnetic tape, a magneto-optical disk (MO), etc.), an optical Memory (e.g., a CD, a DVD, a BD, an HVD, etc.), and a semiconductor Memory (e.g., a ROM, an EPROM, an EEPROM, a nonvolatile Memory (NAND FLASH), a Solid State Disk (SSD)).
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.

Claims (10)

1. A creep start control method of an electric vehicle is characterized by comprising the following steps:
when the creep starts, the creep is started,
s1, acquiring a required output torque based on the current torque and a preset vehicle speed-time curve;
s2, acquiring the actual output torque and acceleration of the vehicle in the time period from the beginning of creeping to the current moment, and determining an actual resistance-overcoming torque-time curve;
s3, acquiring the required output torque for overcoming the predicted resistance according to the actual resistance-overcoming torque-time curve;
and S4, determining the required output torque or the required output torque for overcoming the predicted resistance to be executed by the vehicle according to preset judgment conditions.
2. The method according to claim 1, wherein step S1 includes:
determining the current vehicle running acceleration according to the preset vehicle speed-time curve;
determining the current rotating speed acceleration according to the current vehicle running acceleration; wherein the current rotational speed and the current vehicle running acceleration are positively correlated;
and determining the required output torque according to the current rotating speed acceleration.
3. The method according to claim 1, wherein step S3 includes:
selecting data for acquiring the required output torque for overcoming the predicted resistance from the actual resistance-overcoming torque-time curve;
and judging the variability of the selected data, and calculating the required output torque for overcoming the predicted resistance.
4. The method of claim 3, wherein said selecting data for obtaining said predicted resistance torque overcoming profile in said actual resistance torque overcoming versus time profile comprises:
if the data volume from the beginning of crawling to the current moment is less than N, determining the required output torque for overcoming the predicted resistance according to all the data from the beginning of crawling to the current moment;
and if the data volume from the beginning of crawling to the current moment is more than or equal to N, determining the required output torque for overcoming the predicted resistance according to the data at the current moment and N-1 data before the current moment.
5. A method according to claim 3, characterized in that the variability of the selected data is judged by:
when the selected data accords with a monotonicity screening condition, the output torque of the predicted resistance overcoming requirement is equal to the actual resistance overcoming torque at the previous moment;
when the selected data meets the disorder change screening condition, the required output torque T for overcoming the predicted resistancen+1Obtained by the following method:
Figure FDA0003319886580000021
wherein k isiAs a weighting coefficient, T, related to the time differenceiAnd N is a preset acquired data volume for the actual overcome resistance torque at a certain moment in the actual overcome resistance torque-time curve.
6. The method according to claim 1, wherein step S4 includes:
determining a predicted vehicle speed acceleration according to the required output torque, the actual overcome resistance torque and the required output torque for overcoming the predicted resistance;
and controlling the vehicle to execute the required output torque or the required output torque for overcoming the predicted resistance according to whether the vehicle speed acceleration meets the preset judgment condition.
7. The method according to claim 6, wherein the preset judgment condition is:
when the error between the predicted vehicle speed acceleration and the acceleration corresponding to the vehicle speed in the preset vehicle speed-time curve does not exceed a preset threshold value, controlling the vehicle to execute the required output torque;
and when the error between the predicted vehicle speed acceleration and the acceleration corresponding to the vehicle speed in the preset vehicle speed-time curve exceeds a preset threshold value, controlling the vehicle to execute the required output torque for overcoming the predicted resistance.
8. The method according to claim 1, wherein step S4 further comprises:
acquiring a current vehicle speed;
determining the next vehicle speed value after the current vehicle speed in the preset vehicle speed-time curve;
and determining the acceleration corresponding to the next vehicle speed value according to the preset vehicle speed-time curve, and determining the required target torque corresponding to the next vehicle speed value according to the acceleration corresponding to the next vehicle speed value.
9. The method of claim 1, further comprising: and repeating the steps S1-S4 until the vehicle speed of the vehicle reaches a stable value in the preset vehicle speed-time curve.
10. A creep start control apparatus comprising:
the first acquisition module is used for acquiring the required output torque based on the current torque and a preset vehicle speed-time curve;
the second acquisition module is used for acquiring the actual output torque and the acceleration of the vehicle in the time period from the beginning of crawling to the current moment and determining an actual resistance-overcoming torque-time curve;
the resistance prediction module is used for acquiring the required output torque for overcoming the predicted resistance according to the torque-time curve of the actual overcome resistance;
and the judging module is used for determining that the vehicle executes the required output torque or the required output torque for overcoming the predicted resistance according to a preset judging condition.
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