CN111002995B

CN111002995B - Method and system for controlling speed of electric vehicle

Info

Publication number: CN111002995B
Application number: CN201911388283.0A
Authority: CN
Inventors: 陈富昊; 李翱
Original assignee: Shandong Guohui'an Chuang Intelligent Iot Development Co ltd
Current assignee: Shandong Guohui'an Chuang Intelligent Iot Development Co ltd
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2020-11-20
Anticipated expiration: 2039-12-30
Also published as: CN111002995A

Abstract

The application discloses a method for controlling the speed of an electric vehicle, which comprises the following steps: the remote communication terminal T-Box of the electric vehicle sends driving data of the electric vehicle to the server, and the server generates a current driving path of the electric vehicle according to the driving data of the electric vehicle and prestored electronic map information and determines path characteristics. The T-Box receives a plurality of speed limit values issued by the server in a plurality of times and the speed limit target of the current running path of the electric vehicle, and determines the speed reduction step length according to the size relationship between the speed limit value issued by the server each time and the current running speed of the electric vehicle. And sending the speed reduction step length, the speed limit value and the speed limit target to a controller of the electric vehicle, so that the controller can adjust the current running speed of the electric vehicle in real time until the current running speed of the electric vehicle is lower than the speed limit value and lower than the speed limit target. This application realizes dual safety guarantee to the control of electric motor car speed through above-mentioned technical scheme, has improved the reliability of speed control simultaneously.

Description

Method and system for controlling speed of electric vehicle

Technical Field

The application relates to the technical field of electric vehicles, in particular to a method and a system for controlling the speed of an electric vehicle.

Background

With the rapid development of social economy, the living standard of people is continuously improved, the number of automobiles per capita also shows a trend of increasing year by year, and the condition of road traffic jam is more serious. Therefore, more and more people select two-wheeled or three-wheeled electric vehicles as short-distance travel vehicles to avoid road congestion and increase travel time. However, due to the factors of congestion of the driving road of the electric vehicle, short time and the like, the electric vehicle driver often drives at a higher speed, and great potential danger is brought to road traffic participants. Therefore, it is necessary to effectively control the traveling speed of the electric vehicle.

In the aspect of the existing motion speed control theory, a Proportion, an Integral and a Differential (PID) algorithm for controlling according to deviation, an optimal control theory, a sliding theory model, a fuzzy control theory and the like are mainly provided. However, in practical applications, these control theories or algorithms are mostly applied to vehicles with high driving speeds, such as automobiles. And is not suitable for controlling the speed of an electric vehicle driven at low speed such as two-wheeled or three-wheeled vehicles. Therefore, there is a need for a safety control method for an electric vehicle suitable for low-speed driving such as two-wheeled or three-wheeled vehicles to effectively and safely control the driving speed of the electric vehicle.

Disclosure of Invention

The embodiment of the application provides a safe control method and a safe control system for the speed of an electric vehicle, which are used for solving the technical problem that the existing electric vehicle driven by two wheels, three wheels or other low speeds lacks an effective and safe control method.

In one aspect, an embodiment of the present application provides a method for controlling a speed of an electric vehicle, including: the remote communication terminal T-Box of the electric vehicle sends the driving data of the electric vehicle to the server, so that the server generates the current driving path of the electric vehicle according to the driving data of the electric vehicle and the prestored electronic map information, and determines the path characteristics of the current driving path. The T-Box receives a plurality of speed limit values issued by the server in a plurality of times and the speed limit target of the current running path of the electric vehicle, and determines the speed reduction step length according to the size relationship between the speed limit value issued by the server each time and the current running speed of the electric vehicle. And the plurality of speed limit values are determined by the server in real time according to the driving data and the path characteristics of the electric vehicle. And sending the speed reduction step length, the speed limit value and the speed limit target to a controller of the electric vehicle, so that the controller can adjust the current running speed of the electric vehicle in real time until the current running speed of the electric vehicle is lower than the speed limit value and lower than the speed limit target. The driving data of the electric vehicle comprises at least one or more of the following items: the current position of the electric vehicle and the current running speed of the electric vehicle.

In an implementation manner of the present application, the controller adjusts a current driving speed of the electric vehicle in real time, specifically including: the controller adjusts the current running speed of the electric vehicle to be the difference between the previous running speed of the electric vehicle and the speed reduction step length in real time.

In one implementation manner of the present application, after the controller adjusts the current driving speed of the electric vehicle in real time until the current driving speed of the electric vehicle is lower than the speed limit value, the method further includes: and the T-Box receives the execution result of the speed limit value sent by the controller and feeds the execution result back to the server in real time, so that the server can adjust the speed limit value in real time according to the execution result and the current running speed of the electric vehicle.

In an implementation manner of the present application, the determining of the plurality of speed limit values in real time by the server according to the driving data and the path characteristics of the electric vehicle specifically includes: the server determines the speed limiting starting position of the electric vehicle according to the driving data and the path characteristics of the electric vehicle. And determining the deceleration step length according to the distance between the starting speed limiting position and the corresponding position of the speed limiting target, the current running speed of the electric vehicle and the speed limiting target. The deceleration step length refers to a distance value which is traveled by the electric vehicle when the current running speed of the electric vehicle is reduced to the speed limit value; the speed reduction step refers to a reduction value of the current running speed of the electric vehicle controlled by the controller each time. And adjusting the speed limit value of the electric vehicle in real time according to the deceleration step length, the speed limit starting position and the driving data of the electric vehicle.

In an implementation manner of the present application, the server determines a speed limit starting position of the electric vehicle according to the driving data and the path characteristics of the electric vehicle, and specifically includes: the server determines the initial speed limit value of the electric vehicle on the current running path and the time required for the electric vehicle to decelerate to the initial speed limit value according to the running data and the path characteristics of the electric vehicle. And determining the time required by the electric vehicle to slow down to the speed-limiting target according to the current running speed of the electric vehicle, the speed-limiting target, the distance between the position corresponding to the speed-limiting target and the current position of the electric vehicle. And determining the position of the electric vehicle for starting speed limitation according to the current running speed of the electric vehicle, the initial speed limit value, the time required for the electric vehicle to slow down to the speed limit target and the reserved error buffer distance.

In an implementation manner of the present application, the speed limit value of the electric vehicle is adjusted in real time according to the deceleration step length, the start speed limit position and the driving data of the electric vehicle, and the method specifically includes: and the server actually calculates the distance difference between the current position of the electric vehicle and the speed limit starting position. And adjusting the speed limit value of the electric vehicle in real time according to the multiple relation between the distance difference and the deceleration step length until the speed limit value is lower than the speed limit target. The speed limit is determined by the following formula:

MAX＝A+(V-A)/2ⁿ

wherein MAX is a speed limit value; a is a speed limit target; v is the current running speed of the electric vehicle; n is the multiple relation between the distance difference and the deceleration step length.

In one implementation of the present application, the path characteristics of the current driving path include: dynamic path features, static path features. The static path characteristic is a relatively fixed path characteristic in the prestored electronic map information, is related to a fixed speed limit value of the current driving path of the electric vehicle, and at least comprises one or more of the following items: speed-limiting road sections, no-go road sections and accident-prone road sections. The dynamic path characteristics are temporary or real-time path characteristics in a current driving path of the electric vehicle, and include any one or more of the following items: accidents, traffic control conditions, path congestion conditions, weather features.

In one implementation of the application, the time taken for the controller to adjust the current driving speed of the electric vehicle is less than the time interval between two adjacent T-Box information transmissions. The time for the controller to adjust the current running speed of the electric vehicle is the time for the controller to adjust the current running speed of the electric vehicle until the current running speed is lower than the speed limit value. The information sent by the T-Box is the speed reduction step size and the speed limit value.

On the other hand, the embodiment of the present application further provides a system for controlling a speed of an electric vehicle, including: local control system, server. The local control system comprises a T-Box and a controller. The T-Box is used for sending the driving data of the electric vehicle to the server. The speed limiting device is used for receiving a plurality of speed limiting values issued by the server in times and a speed limiting target of the current running path of the electric vehicle, and determining a speed reduction step length according to the size relationship between the speed limiting value issued by the server each time and the current running speed of the electric vehicle; and sending the speed reduction step length, the speed limit value and the speed limit target to a controller of the electric vehicle. The controller is used for adjusting the current running speed of the electric vehicle in real time until the current running speed of the electric vehicle is lower than the speed limit value and lower than the speed limit target. The server is used for generating a current driving path of the electric vehicle according to the driving data of the electric vehicle and the prestored electronic map information and determining the path characteristics of the current driving path. And the method is also used for determining a plurality of speed limit values and a speed limit target of the current running path in real time according to the running data and the path characteristics of the electric vehicle.

According to the method and the system for controlling the speed of the electric vehicle, data interaction is carried out between the T-Box of the electric vehicle and the server, the driving speed of the electric vehicle is controlled dually, and the safety and the effectiveness of the electric vehicle in the speed reduction process are guaranteed. Meanwhile, the server receives the feedback result sent by the T-Box and records each execution process, so that the speed limit control instruction and the execution result can be inquired, the control reliability is improved, and the control effect is optimized. In addition, the control method and the control system provided by the embodiment of the application can be suitable for different terminals and platforms, and are convenient to popularize and use.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is a flowchart of a method for controlling a speed of an electric vehicle according to an embodiment of the present disclosure;

fig. 2 is a schematic flow chart of a method for determining a speed limit of an electric vehicle according to an embodiment of the present application;

fig. 3 is a schematic internal structural diagram of a system for controlling a speed of an electric vehicle according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be described in detail and completely with reference to the following specific embodiments of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The embodiment of the application provides a method and a system for controlling the speed of an electric vehicle, which realize double safety guarantee in the speed control process of the electric vehicle. The technical solutions provided by the embodiments of the present application are described in detail below with reference to the accompanying drawings.

Fig. 1 is a flowchart of a method for controlling a speed of an electric vehicle according to an embodiment of the present application. As shown in fig. 1, the vehicle speed control method includes the steps of:

s101, the remote communication terminal T-Box sends driving data of the electric vehicle.

The electric vehicle is provided with a remote communication terminal (T-Box) which performs data interaction with the server and sends driving data of the electric vehicle to the server in real time. The driving data of the electric vehicle mainly comprises one or more of the following items: the current position of the electric vehicle and the current running speed of the electric vehicle.

In one embodiment of the application, the electric vehicle is an electric vehicle running at low speed, such as two-wheeled or three-wheeled electric vehicle, and the running speed of the electric vehicle running at low speed is 25km/h lower than the current international required maximum running speed of the electric vehicle.

In one embodiment of the application, the electric vehicle T-Box mainly realizes data interaction with the server through wireless communication technology. The wireless communication technology used includes at least one or several of the following: general packet radio service GPRS, narrowband Internet of things technology NB-Iot and low-power local area network wireless standard Lora.

In an embodiment of the application, the T-Box unit of the electric vehicle further has a positioning function implemented by a global navigation satellite system GNSS, so as to obtain positioning information such as a current driving section and a current location of the electric vehicle.

S102, the T-Box receives a plurality of speed limit values and speed limit targets.

After the T-Box sends the electric vehicle driving data to the server, the server determines a speed limit target and a plurality of speed limit values of the electric vehicle on the current driving road section based on the received driving data. The specific determination process is shown in fig. 2.

Fig. 2 is a schematic flow chart of a method for determining a speed limit of an electric vehicle according to an embodiment of the present application, where as shown in fig. 2, the method for determining the speed limit includes the following steps:

s201, the server receives driving data of the electric vehicle.

The server receives and receives driving data such as the current position of the electric vehicle and the current driving data of the electric vehicle sent by the electric vehicle T-Box.

S202, the server determines the path characteristics of the current running road section of the electric vehicle.

And after receiving the current position information of the electric vehicle, the server compares the current position information with the prestored electronic map information to determine the current running path of the electric vehicle and determine the path characteristics of the current running path.

In one embodiment of the present application, the path characteristics of the current travel path include dynamic path characteristics, static path characteristics. The static path characteristic is a relatively fixed path characteristic in the prestored electronic map information and is related to a fixed speed limit value of the current running path of the electric vehicle. The dynamic path characteristics are temporary or real-time path characteristics in the current driving path of the electric vehicle.

In one embodiment of the application, the static path characteristics include at least any one or more of: speed-limiting road sections, no-go road sections and accident-prone road sections.

In one embodiment of the application, the dynamic path features include at least any one or more of: accidents, traffic control conditions, path congestion conditions, weather features.

S203, the server determines the position for starting deceleration and the speed limit target.

After the server determines the path characteristics in S202, the speed limit target of the electric vehicle on the current running path is determined according to the determined dynamic path characteristics and the determined static path characteristics. And determining the starting speed limiting position of the electric vehicle according to the driving data and the path characteristics of the electric vehicle.

In one embodiment of the application, the starting speed limiting position of the electric vehicle is determined according to the driving data and the path characteristics of the electric vehicle, and the method is realized by the following steps:

firstly, the server determines the initial speed limit value of the electric vehicle on the current running path and the time required for the electric vehicle to reduce the speed from the current running speed to the initial speed limit value according to the running data and the path characteristics of the electric vehicle. And secondly, the server determines the time required by the electric vehicle to decelerate from the current running speed to the speed limit target according to the current running speed of the electric vehicle, the speed limit target of the current running road section, the distance between the position corresponding to the speed limit target and the current position of the electric vehicle. And finally, determining the position of the electric vehicle for starting speed limitation according to the current running speed of the electric vehicle, the initial speed limit value, the time required for the electric vehicle to slow down to the speed limit target and the reserved error buffer distance.

In one embodiment of the application, in the process of determining the speed limiting starting position of the electric vehicle, the cache distance of the electric vehicle is reserved, and the speed of the electric vehicle is reduced to the speed limiting target of the current driving road section before entering the speed limiting road section.

And S204, determining the deceleration step length of the electric vehicle.

And after the server determines the speed limiting starting position and the speed limiting target of the electric vehicle, determining the speed reduction step length of the electric vehicle in the speed reduction process.

In one embodiment of the application, the deceleration step is set as the distance of the path traveled by the electric vehicle in the process of reducing the current running speed of the electric vehicle to the speed limit value. That is, the electric vehicle is to reduce the speed from the current running speed to the speed limit within one deceleration step.

It should be noted that the speed limit value here is not the speed limit target of the electric vehicle on the current path, but is a buffer speed limit value in the process that the electric vehicle decreases from the current speed to the speed limit target. The danger to the electric vehicle driver caused by excessive speed reduction of the electric vehicle is avoided.

And S205, the server adjusts the speed limit value in real time.

And after the server determines the speed limit target, the speed limit starting position and the speed reduction step length of the electric vehicle according to the driving data of the electric vehicle sent by the T-Box and the electronic map information prestored by the server, the speed limit value of the electric vehicle is adjusted in real time according to the information and the driving data of the electric vehicle.

In one embodiment of the application, the server records a plurality of speed limit values in the real-time adjustment process, and sends the plurality of speed limit values to the T-Box of the electric vehicle in a grading manner according to the driving data of the electric vehicle.

In an embodiment of the application, the server adjusts the speed limit value issued to the T-Box in real time, and the method is realized by the following steps:

firstly, the server calculates the distance difference between the current position of the electric vehicle and the position for starting speed limiting in real time according to the driving data of the electric vehicle. Then, a multiple relationship between the distance difference between the two and the deceleration step determined in S204 is determined. And finally, determining the speed limit value in real time through the following formula:

MAX＝A+(V-A)/2ⁿ

S103, determining the size relation between the speed limit value and the current running speed of the electric vehicle by the T-Box.

And after the T-Box receives the speed limit value and the speed limit target sent by the server, determining the size relation between the speed limit value and the current running speed of the electric vehicle.

In one embodiment of the application, the plurality of speed limit values determined by the server are T-boxes transmitted to the electric vehicle in divided times. And after the T-Box receives the speed limit value every time, judging the size relation between the speed limit value and the current running speed of the electric vehicle.

In one embodiment of the application, if the T-Box determines that the current running speed of the electric vehicle is lower than the speed limit value issued by the server, the speed limit value is not sent to a controller of the electric vehicle, but the current running speed of the electric vehicle is directly fed back to the server. And continuously receiving the new speed limit value determined by the server.

In another embodiment of the application, if the T-Box determines that the current running speed of the electric vehicle is higher than the speed limit value issued by the server, the speed limit value is sent to a controller of the electric vehicle, and the controller executes the speed reduction process of the electric vehicle.

S104, determining the speed reduction step by the T-Box.

In S103, after the T-Box determines that the speed limit value is lower than the current running speed of the electric vehicle, the speed reduction step length of the electric vehicle is determined.

In one embodiment of the present application, the speed reduction step refers to a reduction value of the speed of the electric vehicle each time the controller of the electric vehicle controls the driving speed of the electric vehicle.

It should be noted that the deceleration step here is different from the deceleration step in S204. The speed reduction step length is the step length of the reduction of the running speed of the electric vehicle determined by the T-Box; the speed reduction step length is determined by the server, and the step length of the running distance of the electric vehicle is obtained in the process that the running speed of the electric vehicle is reduced to the speed limit value.

And S105, the T-Box sends the speed limit value, the speed limit target and the speed step length to the controller together.

After S104, the speed reduction step length is determined, and the T-Box sends the speed limit value and the speed limit target to the controller and simultaneously sends the speed reduction step length together.

In an embodiment of the present application, the T-Box of the electric vehicle communicates with the controller through an interface manner, where the interface manner includes at least one or more of the following: serial port mode, parallel port mode and bus mode.

S106, the controller executes the speed reduction process of the electric vehicle and feeds back the execution result.

And after the controller of the electric vehicle receives the speed limit value, the speed limit target and the speed reduction step length, controlling the speed of the electric vehicle to be reduced to the speed limit value from the current running speed.

In one embodiment of the application, the controller controls the speed of the electric vehicle to be reduced to the speed limit value from the current running speed, and the speed limit value is not finished at one time, but is executed for multiple times according to the speed reduction step length issued by the T-Box.

In one embodiment of the application, the controller controls the running speed of the electric vehicle to be reduced by one speed reduction step at each time until the current running speed of the electric vehicle is lower than the speed limit value.

In one embodiment of the application, the controller controls the speed of the electric vehicle to decrease for a plurality of times according to a plurality of speed limit values sent by the received T-Box until the current running speed of the electric vehicle is lower than the speed limit target. The safety of the electric vehicle speed reduction is ensured.

In one embodiment of the application, the controller of the electric vehicle sends an execution result to the T-Box every time the controller executes a speed reduction process, so that the T-Box feeds back the execution result of each speed limit value to the server. And after receiving the feedback result sent by the T-Box, the server sends the adjusted speed limit value in real time.

In one embodiment of the application, the time taken by the controller of the electric vehicle to control the speed of the electric vehicle to decrease to the speed limit value each time is shorter than the time taken by the electric vehicle to finish one deceleration step. And ensuring that the server issues a speed limit value after the electric vehicle finishes one speed limit step.

Based on the same inventive concept, the embodiment of the application also provides a system for controlling the speed of the electric vehicle, as shown in fig. 3.

Fig. 3 is a schematic internal structural diagram of a system for controlling a speed of an electric vehicle according to an embodiment of the present application. As shown in fig. 3, the electric vehicle speed control system includes: local control system 301, server 302. The local control 301 system includes a remote communication terminal T-Box303, a controller 304.

In one embodiment of the present application, the T-Box303 is used to send driving data of the electric vehicle to the server 302. The speed limiting device is also used for receiving a plurality of speed limiting values issued by the server 302 in times and a speed limiting target of the current running path of the electric vehicle, and determining a speed reduction step length according to the size relationship between the speed limiting value issued by the server 302 each time and the current running speed of the electric vehicle; and sends the speed reduction step length, the speed limit value and the speed limit target to the controller 304 of the electric vehicle. The server 302 is configured to generate a current driving path of the electric vehicle according to the driving data of the electric vehicle and the pre-stored electronic map information, and determine a path characteristic of the current driving path. And the system is also used for determining a plurality of speed limit values and a speed limit target of the current running path in real time according to the running data of the electric vehicle and the path characteristics. The controller 304 is used for adjusting the current running speed of the electric vehicle in real time until the current running speed of the electric vehicle is lower than the speed limit value and lower than the speed limit target.

It should be noted that, the internal structure of the electric vehicle provided in the embodiments of the present application is not explicitly shown, and all of them are easily known by those skilled in the art.

The embodiments in the present application are described in a progressive manner, and the same and similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the apparatus embodiment, since it is substantially similar to the method embodiment, the description is relatively simple, and for the relevant points, reference may be made to the partial description of the method embodiment.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method of controlling a speed of an electric vehicle, the method comprising:

the method comprises the steps that a remote communication terminal T-Box of the electric vehicle sends driving data of the electric vehicle to a server, so that the server can generate a current driving path of the electric vehicle according to the driving data of the electric vehicle and prestored electronic map information and determine path characteristics of the current driving path;

the T-Box receives a plurality of speed limit values issued by the server in times and a speed limit target of the current running path of the electric vehicle, and determines a speed reduction step length according to the size relationship between the speed limit value issued by the server each time and the current running speed of the electric vehicle; the plurality of speed limit values are determined by the server in real time according to the driving data of the electric vehicle and the path characteristics;

sending the speed reduction step length, the speed limit value and the speed limit target to a controller of the electric vehicle, so that the controller can adjust the current running speed of the electric vehicle in real time until the current running speed of the electric vehicle is lower than the speed limit value and lower than the speed limit target; the method specifically comprises the following steps:

the controller controls the current running speed of the electric vehicle to decrease by one speed reduction step length each time until the current running speed of the electric vehicle is lower than the speed limit value;

the controller controls the current running speed of the electric vehicle to decrease for multiple times according to multiple speed limit values sent by the T-Box until the current running speed of the electric vehicle is lower than the speed limit target;

the driving data of the electric vehicle comprises at least one or more of the following items: the current position of the electric vehicle, and the current running speed of the electric vehicle.

2. The method according to claim 1, wherein the controller adjusts the current driving speed of the electric vehicle in real time, specifically comprising:

and the controller adjusts the current running speed of the electric vehicle to be the difference between the previous running speed of the electric vehicle and the speed reduction step length in real time.

3. The method of claim 1, wherein after the controller adjusts the current driving speed of the electric vehicle in real time until the current driving speed of the electric vehicle is lower than the speed limit value, the method further comprises:

and the T-Box receives the execution result of the speed limit value sent by the controller and feeds the execution result back to the server in real time, so that the server can adjust the speed limit value in real time according to the execution result and the current running speed of the electric vehicle.

4. The method according to claim 1, wherein the plurality of speed limit values are determined by the server in real time according to the driving data of the electric vehicle and the path characteristics, and specifically comprises:

the server determines the starting speed limiting position of the electric vehicle according to the driving data of the electric vehicle and the path characteristics;

determining a deceleration step length according to the distance between the starting speed limiting position and the position corresponding to the speed limiting target, the current running speed of the electric vehicle and the speed limiting target; the speed reduction step length refers to the current running speed of the electric vehicle and the distance value traveled when the speed is reduced to the speed limit value, and the speed reduction step length refers to the reduction value of the current running speed of the electric vehicle controlled by the controller each time;

and adjusting the speed limit value of the electric vehicle in real time according to the deceleration step length, the speed limit starting position and the driving data of the electric vehicle.

5. The method according to claim 4, wherein the server determines the starting speed-limiting position of the electric vehicle according to the driving data of the electric vehicle and the path characteristics, and specifically comprises:

the server determines an initial speed limit value of the electric vehicle on the current running path and the time required for the electric vehicle to decelerate to the initial speed limit value according to the running data of the electric vehicle and the path characteristics;

determining the time required by the electric vehicle to slow down to the speed limit target according to the current running speed of the electric vehicle, the speed limit target, the distance between the position corresponding to the speed limit target and the current position of the electric vehicle;

and determining the position of the electric vehicle for starting speed limitation according to the current running speed of the electric vehicle, the initial speed limit value, the time required for the electric vehicle to slow down to the speed limit target and the reserved error buffer distance.

6. The method according to claim 4, wherein the adjusting the speed limit value of the electric vehicle in real time according to the deceleration step length, the starting speed limit position and the driving data of the electric vehicle specifically comprises:

the server actually calculates the distance difference between the current position of the electric vehicle and the speed limit starting position;

adjusting the speed limit value of the electric vehicle in real time according to the multiple relation between the distance difference value and the deceleration step length until the speed limit value is lower than the speed limit target;

the speed limit value is determined by the following formula:

MAX＝A+(V-A)/2ⁿ

7. The method of claim 1, wherein the path characteristics of the current travel path comprise: dynamic path features, static path features;

the static path characteristic is a relatively fixed path characteristic in the pre-stored electronic map information, is related to a fixed speed limit value of the current driving path of the electric vehicle, and at least comprises any one or more of the following items: speed-limiting road sections, no-go road sections and accident multi-occurrence road sections;

the dynamic path characteristics are temporary or real-time path characteristics in the current driving path of the electric vehicle, and at least include any one or more of the following items: accidents, traffic control conditions, path congestion conditions, weather features.

8. The method according to claim 1, wherein the controller adjusts the current driving speed of the electric vehicle for a time less than a time interval between two adjacent times of transmission of information by the T-Box; the time for the controller to adjust the current running speed of the electric vehicle is the time for the controller to adjust the current running speed of the electric vehicle until the current running speed is lower than the speed limit value, and the information sent by the T-Box is the speed reduction step length and the speed limit value.

9. A system for controlling the speed of an electric vehicle, the system comprising: a local control system, a server; the local control system comprises a T-Box and a controller;

the T-Box is used for sending the driving data of the electric vehicle to the server; the speed limiting device is used for receiving a plurality of speed limiting values issued by the server in a plurality of times and a speed limiting target of the current running path of the electric vehicle, and determining a speed reduction step length according to the size relation between the speed limiting value issued by the server each time and the current running speed of the electric vehicle; sending the speed reduction step length, the speed limit value and the speed limit target to a controller of the electric vehicle;

the server is used for generating a current driving path of the electric vehicle according to the driving data of the electric vehicle and prestored electronic map information and determining path characteristics of the current driving path; the system is also used for determining a plurality of speed limit values and a speed limit target of the current running path in real time according to the running data of the electric vehicle and the path characteristics;

the controller is used for adjusting the current running speed of the electric vehicle in real time until the current running speed of the electric vehicle is lower than the speed limit value and lower than the speed limit target; the method specifically comprises the following steps:

and the controller controls the current running speed of the electric vehicle to decrease for multiple times according to multiple speed limit values sent by the T-Box until the current running speed of the electric vehicle is lower than the speed limit target.