CN109515213B

CN109515213B - Speed limit control method and system for new energy vehicle

Info

Publication number: CN109515213B
Application number: CN201811535963.6A
Authority: CN
Inventors: 陈兴钊; 王旦; 童维勇
Original assignee: Shenzhen Yingweiteng Electric Vehicle Drive Technology Co ltd
Current assignee: Shenzhen Yingweiteng Electric Vehicle Drive Technology Co ltd
Priority date: 2018-12-14
Filing date: 2018-12-14
Publication date: 2020-10-27
Anticipated expiration: 2038-12-14
Also published as: CN109515213A

Abstract

The invention discloses a speed limit control method of a new energy vehicle, which comprises the following steps: acquiring the motor rotating speed and the rotating speed change rate of the vehicle; when the rotating speed and the rotating speed change rate of the motor at the first moment are judged to accord with a first torque reduction trigger rule, determining the value of a corresponding torque reduction coefficient, and controlling the vehicle to enter a torque reduction state; determining the actual torque at the current moment by using the vehicle gear at the current moment, the torque change step length calculated by the torque reduction coefficient and the actual torque at the previous moment, wherein the absolute value of the actual torque at the current moment is lower than that of the actual torque at the previous moment; and when the difference value between the target speed limit point at the second moment and the motor rotating speed is judged to be larger than a preset first threshold value, controlling the vehicle to enter a default state so as to enable the actual torque to be equal to the target torque analyzed by the accelerator pedal. By applying the scheme of the invention, the speed limit control can be conveniently carried out. The invention also discloses a speed limit control system of the new energy vehicle, and the speed limit control system has corresponding effects.

Description

Speed limit control method and system for new energy vehicle

Technical Field

The invention relates to the technical field of new energy vehicles, in particular to a speed limit control method and system of a new energy vehicle.

Background

With the vigorous advocation of new energy vehicles by countries and society, new energy vehicles have been continuously developed and are increasingly widely used.

New energy vehicles, especially pure electric vehicles, need to control the motor speed of the vehicle within a certain range due to the performance requirements of the motor and the motor controller. In the prior art, the control of the motor rotation speed of the new energy vehicle is generally realized by a motor controller or a vehicle controller by adopting a PID (proportion integration differentiation) regulation algorithm. Although the PID algorithm can obtain better accuracy, the coefficient setting of the PID algorithm of a specific vehicle needs to be obtained through experimental data, which is time-consuming and labor-consuming. This is because there are many vehicle parameters that affect the PID coefficient, and for example, the reduction gear ratio of the vehicle, the tire radius of the vehicle, and the like, and since vehicle parameters of different brands and models differ, the conventional proposal is to experimentally set the PID coefficient of the vehicle at the time of vehicle production.

In summary, how to more conveniently control the speed limit of the new energy vehicle is a technical problem that needs to be solved urgently by those skilled in the art at present.

Disclosure of Invention

The invention aims to provide a speed-limiting control method of a new energy vehicle, so as to conveniently control the speed limit of the new energy vehicle.

In order to solve the technical problems, the invention provides the following technical scheme:

a speed limit control method of a new energy vehicle comprises the following steps:

acquiring the motor rotating speed and the rotating speed change rate of the vehicle;

when the rotating speed and the rotating speed change rate of the motor at the first moment are judged to accord with a preset first torque reduction triggering rule, determining the value of a corresponding torque reduction coefficient, and controlling the vehicle to enter a torque reduction state;

calculating a torque change step length according to the torque reduction coefficient;

determining the actual torque at the current moment by using the gear of the vehicle at the current moment, the torque change step length and the actual torque at the previous moment, so as to control the vehicle based on the determined actual torque, wherein the absolute value of the actual torque at the current moment is lower than that of the actual torque at the previous moment;

and when the delta Spd at the second moment is judged to be larger than a preset first threshold value, controlling the vehicle to exit the torque reduction state and enter a default state so that the actual torque of the vehicle is equal to the target torque analyzed by an accelerator pedal, wherein the delta Spd is the difference value between the target speed limit point and the motor rotating speed.

Preferably, after determining the actual torque at the current time to control the vehicle by using the gear of the vehicle at the current time, the torque change step size, and the actual torque at the previous time, and before controlling the vehicle to exit the torque reduction state and enter the default state, the method further includes:

and when the rotating speed and the rotating speed change rate of the motor at the third moment are judged to accord with a preset first transition triggering rule, controlling the vehicle to exit the torque reduction state and enter a transition state, and keeping the actual torque to be the same as the actual torque at the initial moment of entering the transition state in the transition state.

Preferably, after the controlling the vehicle to exit the torque-down state and enter the transition state, the method further includes:

when the rotating speed and the rotating speed change rate of the motor at the fourth moment are judged to accord with a preset torque-increasing triggering rule, determining the value of a corresponding torque-increasing coefficient, and controlling the vehicle to enter a torque-increasing state;

calculating a torque change step length according to the torque increasing coefficient;

determining the actual torque at the current moment by using the gear of the vehicle at the current moment, the torque change step length and the actual torque at the previous moment, wherein the absolute value of the actual torque at the current moment is greater than that of the actual torque at the previous moment;

when the rotating speed and the rotating speed change rate of the motor at the fifth moment are judged to accord with a preset second transition triggering rule, controlling the vehicle to exit the torque increasing state and enter the transition state, and keeping the actual torque to be the same as the actual torque at the initial moment when the torque increasing state enters the transition state in the transition state;

when the rotating speed and the rotating speed change rate of the motor at the fifth moment are judged to be not in accordance with the second transition triggering rule, but the delta Spd at the fifth moment is larger than the first threshold, controlling the vehicle to exit the torque increasing state and enter the default state, so that the actual torque of the vehicle is equal to the target torque analyzed by an accelerator pedal;

and when the rotating speed and the rotating speed change rate of the motor at the fifth moment are judged not to accord with the second transition triggering rule, and the delta Spd at the fifth moment is smaller than or equal to the first threshold value, keeping the torque increasing state.

and when the rotating speed and the rotating speed change rate of the motor at the sixth moment are judged to accord with a preset second torque reduction trigger rule, controlling the vehicle to exit from the transition state and enter a torque reduction state, wherein the value of the torque reduction coefficient is a preset torque reduction regulation coefficient value after entering the torque reduction state.

Preferably, the calculating a torque change step according to the torque reduction coefficient includes:

determining the absolute value of the delta Spd at the current moment;

and taking the product of the absolute value and the torque reduction coefficient as a calculated torque change step length.

Preferably, the determining, by using the gear of the vehicle at the current time, the torque change step size, and the actual torque at the previous time, the actual torque at the current time to control the vehicle based on the determined actual torque, and the absolute value of the actual torque at the current time being lower than the absolute value of the actual torque at the previous time includes:

when the vehicle is in a forward gear, determining the actual torque at the current moment by using the difference value between the actual torque at the last moment of the vehicle and the torque change step length;

and when the vehicle is in a reverse gear, determining the actual torque at the current moment by using the sum of the actual torque at the last moment of the vehicle and the torque change step length.

Preferably, when the vehicle is in a forward gear, determining the actual torque at the current time by using the difference between the actual torque at the last time of the vehicle and the torque change step size includes:

when the vehicle is in a forward gear, calculating a difference value between the actual torque of the vehicle at the previous moment and the torque change step length;

when the difference value is judged to be less than or equal to 0, taking the smaller value of the target torque analyzed by the accelerator pedal of the vehicle and 0 as the determined actual torque at the current moment;

and when the difference is larger than 0, taking the smaller value of the target torque analyzed by the accelerator pedal of the vehicle and the difference as the determined actual torque at the current moment.

Preferably, when it is determined that the rotation speed and the rotation speed change rate of the motor at the third time meet a preset first transition trigger rule, controlling the vehicle to exit the torque reduction state and enter a transition state includes:

performing judgment according to the sequence from 1 to M of the value of q, and controlling the vehicle to exit from the torque-down state and enter a transition state when the delta Spd at the third moment is judged to be greater than a q-th torque-down exit speed judgment point and the rotating speed change rate at the third moment is greater than a q-th torque-down exit rotating speed change rate judgment point;

wherein q and M are positive integers, q is more than or equal to 1 and less than or equal to M, the values of the M torque-down exit speed judgment points are less than 0, and are sequentially increased from the 1 st torque-down exit speed judgment point to the M th torque-down exit speed judgment point, the values of the M torque-down exit speed change rate judgment points are less than 0, and are sequentially increased from the 1 st torque-down exit speed change rate judgment point to the M th torque-down exit speed change rate judgment point.

Preferably, when the motor speed and the speed change rate at the first moment are determined to meet a preset first torque reduction trigger rule, determining a value of a corresponding torque reduction coefficient, and controlling the vehicle to enter a torque reduction state, including:

performing judgment according to the sequence from 1 to N of the value of i, and when the delta Spd at the first moment is judged to be smaller than the ith torque reduction starting speed judgment point and the rotating speed change rate at the first moment is judged to be larger than the ith torque reduction starting rotating speed change rate judgment point, determining the value of a torque reduction coefficient as a preset ith torque reduction coefficient value, and controlling the vehicle to enter a torque reduction state;

wherein i and N are positive integers, i is more than or equal to 1 and less than or equal to N, the values of N torque-reduction starting speed judging points are sequentially reduced from a1 st torque-reduction starting speed judging point to an Nth torque-reduction starting speed judging point, the values of N torque-reduction starting speed change rate judging points are sequentially reduced from the 1 st torque-reduction starting speed change rate judging point to the Nth torque-reduction starting speed change rate judging point, and the values of N torque-reduction coefficient values are sequentially reduced from the 1 st torque-reduction coefficient value to the Nth torque-reduction coefficient value.

A speed limit control system of a new energy vehicle comprises:

the information acquisition module is used for acquiring the motor rotating speed and the rotating speed change rate of the vehicle;

the first torque reduction triggering module is used for determining the value of a corresponding torque reduction coefficient and controlling the vehicle to enter a torque reduction state when the rotating speed of the motor and the rotating speed change rate at the first moment are judged to accord with a preset first torque reduction triggering rule;

the torque reduction step length calculation module is used for calculating a torque change step length according to the torque reduction coefficient;

the torque reduction adjusting module is used for determining the actual torque at the current moment by utilizing the gear of the vehicle at the current moment, the torque change step length and the actual torque at the previous moment so as to control the vehicle based on the determined actual torque, and the absolute value of the actual torque at the current moment is lower than that of the actual torque at the previous moment;

and the first recovery module is used for controlling the vehicle to exit the torque reduction state and enter a default state when the fact that the delta Spd at the second moment is larger than a preset first threshold value is judged, so that the actual torque of the vehicle is equal to the target torque analyzed by an accelerator pedal, and the delta Spd is equal to the difference value between the target speed limit point and the motor rotating speed.

By applying the technical scheme provided by the embodiment of the invention, the speed limit control of the vehicle is carried out by acquiring the motor rotating speed and the rotating speed change rate of the vehicle, so that the method and the device are suitable for different types of vehicles and are convenient to implement. Specifically, after the motor speed and the speed change rate of the vehicle are obtained, when the motor speed and the speed change rate at the first moment are judged to accord with a preset first torque reduction trigger rule, the value of the corresponding torque reduction coefficient is determined, and the vehicle is controlled to enter a torque reduction state. The value of the torque reduction coefficient can be used for calculating the step length of torque change, and further, when the vehicle is in a torque reduction state, the absolute value of the actual torque at the current moment is lower than the absolute value of the actual torque at the previous moment. The absolute value of the actual torque is reduced, namely the acceleration of the vehicle is reduced, the increase of the rotating speed of the motor of the vehicle is slowed, and the speed limit is realized. And when the delta Spd at the second moment is judged to be larger than the preset first threshold, the motor rotating speed of the vehicle at the second moment is already low, and the default state can be recovered, so that the actual torque of the vehicle is equal to the target torque analyzed by the accelerator pedal, namely the speed limit control is quitted.

Drawings

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

FIG. 1 is a flow chart of an implementation of a method for controlling speed limit of a new energy vehicle according to the invention;

FIG. 2 is a schematic diagram illustrating a variation curve of a motor speed and an actual torque when a default state enters a torque reduction state in an embodiment;

FIG. 3 is a schematic diagram illustrating a variation curve of a motor speed and an actual torque when a torque reduction state enters a transition state in an embodiment;

FIG. 4 is a schematic diagram illustrating a variation curve of a motor speed and an actual torque when a torque-up state enters a transition state in an embodiment;

FIG. 5 is a schematic diagram illustrating a simulation of a rotational speed of a motor according to an embodiment of the present invention;

FIG. 6 is a schematic illustration of a simulation of actual torque in an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a speed limit control system of a new energy vehicle according to the present invention.

Detailed Description

The core of the invention is to provide a speed limit control method of the new energy vehicle, which can conveniently carry out the speed limit control of the new energy vehicle.

In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, fig. 1 is a flowchart illustrating an implementation of a speed limit control method for a new energy vehicle according to the present invention, where the method includes the following steps:

step S101: and acquiring the motor rotating speed and the rotating speed change rate of the vehicle.

The method may obtain the motor speed and the speed change rate of the vehicle in real time, or obtain the motor speed and the speed change rate of the vehicle according to a preset sampling period, and in the specific implementation, the change of the motor speed and the change of the speed change rate of the vehicle are considered to be fast, so the method may generally obtain the motor speed and the speed change rate of the vehicle in real time, or obtain the motor speed and the speed change rate of the vehicle in a shorter sampling period.

Step S102: and when the rotating speed of the motor and the rotating speed change rate at the first moment are judged to accord with a preset first torque reduction triggering rule, determining the value of the corresponding torque reduction coefficient, and controlling the vehicle to enter a torque reduction state.

The first torque reduction triggering rule can be set according to actual needs, for example, a simpler setting mode can be adopted, for example, relevant threshold values are respectively set for the rotating speed and the rotating speed change rate of the motor, and when the set threshold values are met, the torque reduction is determined to be needed, namely, the vehicle is controlled to enter a torque reduction state. When the vehicle enters the torque reduction state from the default state, the number of the torque reduction coefficients required to be set and specific values can be adjusted according to actual needs, and the implementation of the method is not influenced. The control of the vehicle to enter the torque-down state indicates that the operation related to the torque-down state needs to be executed, and the subsequent steps S103 and S104 in the present application are the operations that need to be executed when the vehicle is in the torque-down state.

In a specific embodiment, step S102 may specifically include:

carrying out judgment according to the sequence from 1 to N of the value of i, and when judging that the delta Spd at the first moment is smaller than the ith torque-down starting speed judgment point and the rotating speed change rate at the first moment is larger than the ith torque-down starting rotating speed change rate judgment point, determining that the value of the torque-down coefficient is a preset ith torque-down coefficient value, and controlling the vehicle to enter a torque-down state;

Δ Spd is the difference between the target speed limit point at a certain moment and the motor speed at that moment, and the larger Δ Spd indicates the lower motor speed at that moment. The target speed limit point can be set according to needs, can be preset as a fixed value, can also be adjusted according to the actual running state of the vehicle, and specifically, the target speed limit point can be determined according to the current gear information and the vehicle condition information of the vehicle. The vehicle condition information may include a battery pack state of the vehicle, a motor state, a state of the vehicle controller, and the like. For example, when the vehicle is in D range and the vehicle conditions are normal, the target speed limit point is determined to be 3700rpm, and when the vehicle is in D range and the battery pack is abnormal, the target speed limit point is determined to be 2500 rpm. It should be noted that there may be various update conditions for the target speed limit point, for example, the target speed limit point is re-determined every certain time, and for example, in the scheme of the present application, the target speed limit point is re-determined every time the vehicle switches the state.

In this embodiment, the first torque-down triggering rule includes N sub-rules in total, and the determination is performed in the order from 1 st to nth. For convenience of description and understanding, the case where N is 4 is taken as an example, that is, 4 torque-down start speed determination points need to be preset, the 1 st torque-down start speed determination point is referred to as J01, and correspondingly, the 2 nd to 4 th torque-down start speed determination points are referred to as J02, J03 and J04 in sequence. The torque-down starting speed judgment point is used for judging the vehicle to be switched from the default state to the torque-down state, and J01 & gtJ 02 & gtJ 03 & gtJ 04. The preset 1 st to 4 th torque-down start-up rotation speed change rate determination points are sequentially called A01, A02, A03 and A04, and are also used for determining the torque-down start-up rotation speed change rate of the vehicle from a default state to a torque-down state, wherein A01 is more than A02 is more than A03 is more than A04. The preset 1 st to 4 th torque reduction coefficient values are referred to as a1, a2, a3 and a4 in sequence. In this application, MotorSpdAcc represents a rotation rate change rate.

The first moment can be any moment when the vehicle is in a default state, when Δ Spd of the first moment is less than J01 and MotorSpdAcc is greater than a01, the vehicle needs to be controlled to enter a torque reduction state, and the value of the torque reduction coefficient is a 1. When the sub-rule of Δ Spd < J01 and MotorSpdAcc > a01 is not satisfied, further determining whether the 2 nd sub-rule is satisfied, that is, determining that Δ Spd < J02 and MotorSpdAcc > a02 are satisfied, if so, controlling the vehicle to enter a torque reduction state, and the value of the torque reduction coefficient is a 2. Of course, if none of the 4 sub-rules in this embodiment is satisfied, the vehicle will continue to maintain the default state, and when the vehicle is in the default state, the actual torque of the vehicle is equal to the target torque resolved by the accelerator pedal, that is, the actual torque of the vehicle will not be limited, and is determined by the user.

In this embodiment, the larger the rotation speed change rate when the vehicle triggers torque down, the larger the set torque down coefficient, and the larger the reserved buffer space, where the buffer space described herein refers to the value of the torque down start speed determination point. The speed limiting control of different levels is realized for the vehicle under different acceleration conditions, so that the rotating speed of the motor of the vehicle can be effectively limited within a certain range in different acceleration conditions, and the condition of insufficient torque adjustment or excessive torque adjustment is not easy to occur.

Step S103: and calculating the torque change step length according to the torque reduction coefficient.

In general, the calculation of the torque change step length can be performed by using a basic polynomial, and the specific form setting of the polynomial can be adjusted according to actual conditions. In particular, the torque variation step may be a product of an absolute value of Δ Spd and a value of the determined torque reduction coefficient. That is, step S103 may be specifically: and determining the absolute value of the delta Spd at the current moment, and taking the product of the absolute value and the torque reduction coefficient as the calculated torque change step length. According to the embodiment, the torque change step length is simple and convenient to calculate, and the scheme is convenient to implement.

Step S104: and determining the actual torque at the current moment by using the gear, the torque change step length and the actual torque at the previous moment of the vehicle at the current moment so as to control the vehicle based on the determined actual torque, wherein the absolute value of the actual torque at the current moment is lower than that of the actual torque at the previous moment.

The actual torque at the current moment can be determined by using the gear of the vehicle at the current moment, the torque change step length and the actual torque at the previous moment, and the specific determination mode can be set according to actual needs, but the absolute value of the actual torque at the current moment is required to be lower than that of the actual torque at the previous moment. The absolute value of the actual torque is reduced, which means that the traveling power supplied to the vehicle is reduced, and the acceleration of the vehicle is reduced, so that the rising speed of the motor speed of the vehicle is limited, that is, the increase of the motor speed is slowed, and the speed limit is realized.

In a specific implementation, step S104 may specifically be: when the vehicle is in a forward gear, determining the actual torque at the current moment by using the difference value between the actual torque at the previous moment of the vehicle and the torque change step length; when the vehicle is in a reverse gear, the actual torque at the current moment is determined by using the sum of the actual torque at the last moment of the vehicle and the torque change step length.

When the vehicle is in the forward gear and the actual torque of the vehicle is positive, the actual torque at the current moment is determined by using the difference between the actual torque at the previous moment and the torque change step length in the embodiment. Furthermore, considering the convenience of calculation and control, when the forward gear is in a torque reduction state, the calculated difference value can be directly used as the actual torque, correspondingly, when the reverse gear is in a reverse gear, the actual torque is negative, and the sum of the actual torque and the torque change step length at the last moment of the vehicle can be used as the determined actual torque at the current moment.

Of course, in other embodiments, a more complicated calculation method of the actual torque may be provided to improve the control effect on the vehicle, and avoid the situation that the calculated value is not allowed. Taking the vehicle in the forward gear as an example, the method may specifically include:

when the vehicle is in a forward gear, calculating a difference value between an actual torque and a torque change step length at the last moment of the vehicle;

and when the difference value is larger than 0, taking the smaller value of the target torque analyzed by the accelerator pedal of the vehicle and the difference value as the determined actual torque at the current moment.

In this embodiment, if the calculated difference between the actual torque at the previous time and the torque change step is directly used as the current actual torque, in a small part of cases, the difference may be less than or equal to 0, but some vehicles do not allow deceleration through energy feedback, that is, the actual torque is not allowed to be negative, in this embodiment, the determined actual torque can be made to be 0 at the lowest, and a negative value is avoided. Furthermore, if the calculated difference is larger than the target torque analyzed by the accelerator pedal, the target torque analyzed by the accelerator pedal is used as the determined actual torque, so that the reduction range of the torque can be improved, and the current requirement of a user is met. It should be noted that the actual torque determined in this embodiment is 0 at the lowest, but in other embodiments, when the vehicle is allowed to decelerate by energy feedback, if the calculated difference is negative and equal to or less than the allowable feedback torque value, the allowable feedback torque value may be used as the current actual torque determined.

When the vehicle is in a reverse gear, the principle is similar, namely after the actual torque at the last moment of the vehicle is summed with the torque change step length, when the sum is greater than 0, 0 is taken as the determined actual torque, and when the sum is less than or equal to the target torque analyzed by the accelerator pedal, the target torque analyzed by the accelerator pedal is taken as the determined target torque.

Step S105: and when the delta Spd at the second moment is judged to be larger than a preset first threshold value, controlling the vehicle to exit from the torque reduction state and enter a default state, so that the actual torque of the vehicle is equal to the target torque analyzed by the accelerator pedal, and the delta Spd is equal to the difference value between the target speed limit point and the motor rotating speed.

As the absolute value of the actual torque is decreased, the acceleration of the vehicle is gradually decreased, and the vehicle is decelerated due to the influence of the resistance. When the Δ Spd at the second moment is judged to be larger than the preset first threshold, which indicates that the motor speed of the vehicle is low at the moment, the vehicle can be controlled to exit the torque reduction state and return to the default state, the vehicle enters the default state, and the actual torque of the vehicle is equal to the target torque analyzed by the accelerator pedal.

By applying the method provided by the embodiment of the invention, the speed limit control of the vehicle is carried out by acquiring the motor rotating speed and the rotating speed change rate of the vehicle, so that the method is suitable for different types of vehicles and is convenient to implement. Specifically, after the motor speed and the speed change rate of the vehicle are obtained, when the motor speed and the speed change rate at the first moment are judged to accord with a preset first torque reduction trigger rule, the value of the corresponding torque reduction coefficient is determined, and the vehicle is controlled to enter a torque reduction state. The value of the torque reduction coefficient can be used for calculating the step length of torque change, and further, when the vehicle is in a torque reduction state, the absolute value of the actual torque at the current moment is lower than the absolute value of the actual torque at the previous moment. The absolute value of the actual torque is reduced, namely the acceleration of the vehicle is reduced, the increase of the rotating speed of the motor of the vehicle is slowed, and the speed limit is realized. And when the delta Spd at the second moment is judged to be larger than the preset first threshold, the motor rotating speed of the vehicle at the second moment is already low, and the default state can be recovered, so that the actual torque of the vehicle is equal to the target torque analyzed by the accelerator pedal, namely the speed limit control is quitted.

In an embodiment of the present invention, after step S104 and before step S105, the method may further include:

and when the rotating speed of the motor and the rotating speed change rate at the third moment are judged to accord with a preset first transition triggering rule, controlling the vehicle to exit from a torque reduction state and enter a transition state, and keeping the actual torque to be the same as the actual torque at the initial moment of entering the transition state in the transition state.

In this kind of embodiment, consider that if only setting up and falling the turn round state and default state, the vehicle once triggered the process that falls the turn round state, actual moment of torsion just can constantly reduce, and if the user needs to let the motor speed of vehicle stabilize in a higher numerical value again, this application just passes through the restriction to actual moment of torsion change degree to satisfy this kind of demand to a certain extent.

Similar to the first torque reduction triggering rule described above, the setting of the first transition triggering rule may also be set according to actual needs. For example, in one embodiment, the operation of switching from the torque-down state to the transition state may be specifically:

performing judgment according to the sequence from 1 to M of the value of q, and controlling the vehicle to exit from the torque-down state and enter into a transition state when the delta Spd at the third moment is judged to be larger than the q torque-down exit speed judgment point and the rotation speed change rate at the third moment is larger than the q torque-down exit rotation speed change rate judgment point;

For convenience of description and understanding, the example where M is 4 is taken, that is, 4 torque-down exit speed determination points need to be preset, the 1 st torque-down exit speed determination point is referred to as J1, and correspondingly, the 2 nd to 4 th torque-down exit speed determination points are referred to as J2, J3 and J4 in sequence. The torque-down exit speed judgment point is used for judging whether the vehicle is switched from the torque-down state to the transition state, and J4 & gtJ 3 & gtJ 2 & gtJ 1. The preset 1 st to 4 th torque-down exit rotation speed change rate determination points are sequentially called A1, A2, A and A4, and are also used for determining the transition state of the vehicle from the torque-down state, wherein A4 is more than A3 is more than A2 is more than A1. Generally, the values of the torque-down exit speed determination point and the torque-down exit rotation speed change rate determination point are both less than or equal to 0.

When Δ Spd at the third time is larger than J1 and MotorSpdAcc is smaller than a1, the vehicle needs to be controlled to enter a transition state, and when the vehicle is in the transition state, the actual torque is kept unchanged, and the value of the actual torque is equal to the value of the actual torque at the initial time of entering the transition state. Therefore, the vehicle can be maintained in a transition state in the occasion that the vehicle speed and the torque are relatively stable. When Δ Spd > J1 and the MotorSpdAcc < a1 sub-rule is not satisfied, a further determination is made as to whether Δ Spd > J12 and MotorSpdAcc < a2 are satisfied and, if so, the vehicle is controlled to enter the transition state. Of course, if none of the 4 sub-rules in this embodiment is satisfied, the vehicle will continue to maintain the torque down state.

In this embodiment, the larger the absolute value of the rate of change of the rotational speed at which the vehicle triggers the transient state, i.e., the larger the deceleration of the vehicle, the larger the reserved buffer space, which here refers to the absolute value of the torque down exit speed determination point. In this way, it is advantageous to implement different levels of deceleration control for the vehicle under different deceleration conditions, so that the actual torque and the motor rotation speed of the vehicle under different deceleration conditions can be effectively stabilized within a certain range, i.e., enter the transient state.

In one embodiment of the present invention, after controlling the vehicle to exit the torque-down state and enter the transition state, the method further includes:

when the rotating speed and the rotating speed change rate of the motor at the fourth moment are judged to accord with the preset torque-increasing triggering rule, determining the value of the corresponding torque-increasing coefficient, and controlling the vehicle to enter a torque-increasing state;

calculating the torque change step length according to the torque increasing coefficient;

determining the actual torque at the current moment by using the gear, the torque change step length and the actual torque at the previous moment of the vehicle at the current moment, wherein the absolute value of the actual torque at the current moment is greater than that of the actual torque at the previous moment;

when the rotating speed and the rotating speed change rate of the motor at the fifth moment are judged to accord with a preset second transition triggering rule, controlling the vehicle to exit from the torque-up state and enter into a transition state, and keeping the actual torque to be the same as the actual torque at the initial moment when the torque-up state enters into the transition state in the transition state;

when the rotating speed and the rotating speed change rate of the motor at the fifth moment are judged to be not in accordance with the second transition triggering rule, but delta Spd at the fifth moment is larger than a first threshold value, the vehicle is controlled to exit a torque-up state and enter a default state, so that the actual torque of the vehicle is equal to the target torque analyzed by the accelerator pedal;

and when the rotating speed and the rotating speed change rate of the motor at the fifth moment are judged to be not in accordance with the second transition triggering rule, and the delta Spd at the fifth moment is smaller than or equal to the first threshold value, keeping the torque increasing state.

In this embodiment, if the user still needs to maintain the motor speed near the target speed limit point, the torque-up state is increased so that the motor speed can be maintained near the target speed limit point, considering that the vehicle will stay in the transient state for a short time when the speed and the torque change speed of the partial vehicle are high.

The specific torque-up triggering rule may be set according to actual conditions, for example, in one specific embodiment, when Δ Spd at the fourth time is greater than a preset torque-up starting speed threshold J5, and the rotation speed change rate at the fourth time is less than a torque-up starting acceleration threshold a5, the vehicle is controlled to enter a torque-up state, and the value of the torque-up coefficient is determined as a preset value b. In consideration of the fact that the motor speed and the speed change rate of the vehicle in the transient state are generally within a certain range, it is generally not necessary to provide a complex torque-up trigger rule, and in this embodiment, the torque-up trigger rule does not include a plurality of sub-rules, and the judgment can be completed only by J5 and a 5. Of course, in practical application, the torque-up trigger rule can be adjusted according to needs, and the implementation of the invention is not influenced.

After entering the torque-up state, the absolute value of the actual torque of the vehicle gradually increases. After the value of the torque increasing coefficient is determined, the torque change step length can be calculated according to the torque increasing coefficient, the actual torque at the current moment is determined by utilizing the gear of the vehicle at the current moment, the torque change step length and the actual torque at the previous moment, and the absolute value of the actual torque at the current moment is larger than the absolute value of the actual torque at the previous moment. Similar to the torque-down process, the torque change step can be calculated by multiplying the torque-up coefficient by Δ Spd during the torque-up process.

Specifically, when the vehicle is in the forward gear and in the torque-up state, the sum of the actual torque at the last moment of the vehicle and the torque change step length can be directly used as the determined actual torque at the current moment. Correspondingly, when the vehicle is in a reverse gear, the difference value between the actual torque of the vehicle at the previous moment and the torque change step length is used as the determined actual torque at the current moment. Further, similar to the torque reduction state, a limiting condition may be additionally added, that is, in the forward gear, when the calculated sum is less than or equal to 0, 0 is used as the determined actual torque, and when the calculated sum is greater than the target torque resolved by the accelerator pedal, the target torque resolved by the accelerator pedal is used as the determined actual torque. And when the difference is smaller than or equal to the target torque analyzed by the accelerator pedal, taking the target torque analyzed by the accelerator pedal as the determined target torque.

And in the torque increasing state, when the rotating speed and the rotating speed change rate of the motor at the fifth moment are judged to accord with a preset second transition trigger rule, controlling the vehicle to exit the torque increasing state and enter a transition state, and keeping the actual torque to be the same as the actual torque at the initial moment when the torque increasing state enters the transition state in the transition state.

The second transition triggering rule may also be set according to actual needs, for example, in a specific embodiment, whether the following 4 sub-rules are satisfied is sequentially determined:

sub-rule 1: Δ Spd at the fifth time is less than J7, and the rate of change of the rotation speed at the fifth time is greater than a 7;

sub-rule 2: Δ Spd at the fifth time is less than J8, and the rate of change of the rotation speed at the fifth time is greater than a 8;

sub-rule 3: Δ Spd at the fifth time is less than J9, and the rate of change of the rotation speed at the fifth time is greater than a 9;

sub-rule 4: Δ Spd at the fifth time is less than J10, and the rate of change of the rotation speed at the fifth time is greater than a 10;

j7 > J8 > J9 > J10, A7 > A8 > A9 > A10. If any of the 4 sub-rules is true, it can be determined that the second transition trigger rule in this embodiment is satisfied. Meanwhile, the comparison result between Δ Spd at the fifth time and the first threshold value is combined to determine whether the vehicle needs to be controlled to return to the default state, enter the transition state, or maintain the torque-up state.

The foregoing embodiments describe the operation of transitioning from the transition state to the raise-button or default state. In specific implementation, in some occasions, the vehicle may need to return to the torque reduction state from the transition state, that is, when the vehicle is in the transition state, and when the rotation speed and the rotation speed change rate of the motor at the sixth moment are judged to meet the preset second torque reduction trigger rule, the vehicle is controlled to exit from the transition state and enter the torque reduction state, and the value of the torque reduction coefficient after entering the torque reduction state is the preset torque reduction adjustment coefficient value. Specifically, the vehicle may be controlled to transition from the transition state to the torque-down state when Δ Spd at the sixth time is less than the torque-down start speed threshold J6, and the rate of change of the rotational speed at the sixth time is less than the torque-down start acceleration threshold a 6.

Referring to FIG. 2, for a light truck as an example, the target speed limit point is 3676rpm for forward gear and 612rpm for reverse gear. And setting:

sequentially taking values of 4 torque-down starting speed judgment points used for switching from the default state to the torque-down state as J01-160 rpm, J02-82 rpm, J03-41 rpm and J04-20 rpm; sequentially taking the values of 4 torque-reduction starting rotation speed change rate judgment points as A01-6 rpm/s, A02-3 rpm/s, A03-2 rpm/s and A04-0 rpm/s; the values of the 4 torque-reducing coefficient values are sequentially a 1-4, a 2-2, a 3-1 and a 4-0.4.

Sequentially taking values of 4 torque-down exit speed judgment points used for switching from the torque-down state to the transition state as J1-41 rpm, J2-20 rpm, J3-10 rpm and J4-2 rpm; and 4 torque-reduction withdrawal rotation speed change rate judgment points are sequentially set as A1-1.5 rpm/s, A2-0.6 rpm/s, A3-0.3 rpm/s and A4-0 rpm/s.

The torque-up starting speed threshold value J5 used for the transition from the transition state to the torque-up state is 5, the torque-up starting acceleration threshold value A5 is 0, and the preset value b of the torque-up coefficient is 0.3.

The relevant speed threshold value J6 used for the transition from the transition state to the torque-down state is-5, the torque-down starting acceleration threshold value A6 is 0, and the torque-down regulating coefficient value a5 is 0.2.

Sequentially taking the values of 4 torque-up and torque-off speed judgment points used for switching from the torque-up state to the transition state as J7-41 rpm, J7-20 rpm, J9-10 rpm and J10-5 rpm; the values of the 4 judgment points of the torque-up withdrawal rotation speed change rate are sequentially A7-1.5 rpm/s, A8-0.6 rpm/s, A9-0.3 rpm/s and A10-0 rpm/s.

The first threshold was set at 200 rpm.

Fig. 2 shows a schematic diagram of a variation curve of the motor speed and the actual torque when the default state enters the torque reduction state in the embodiment. It can be seen that the greater the rate of change of the rotational speed at which the vehicle triggers torque down, the faster the present solution controls the actual torque down.

Fig. 3 is a schematic diagram of a variation curve of the motor rotation speed and the actual torque when the torque reduction state enters the transition state in the embodiment. The larger the deceleration of the vehicle is, the more easily the motor rotation speed of the vehicle returns to the normal range, and the larger the absolute value of the torque down exit speed determination point is set.

Fig. 4 is a schematic diagram of a variation curve of the motor rotation speed and the actual torque when the torque increasing state enters the transition state in the embodiment. The greater the acceleration of the vehicle, i.e., the greater the rate of change of the rotation speed, the more easily the motor rotation speed of the vehicle reaches or even exceeds the target speed limit point, the greater the absolute value of the set torque-up exit speed determination point.

It should be further noted that, in fig. 2, fig. 3, and fig. 4, it is convenient to draw, and the motor rotation speed and the actual torque are drawn according to a uniform change manner, which shows that corresponding trigger rules are different when the rotation speed change rate and the motor rotation speed are different, so that the change degree of the actual torque is different, and shows a configuration manner of corresponding speed determination points for different rotation speed change rates, and it is not limited that the motor rotation speed and the actual torque are necessarily uniformly changed. In practical application, the change of the motor rotation speed and the actual torque is nonlinear change, and as can be seen from fig. 5 and fig. 6, by applying the scheme of the application, the motor rotation speed can be kept near the set target speed limit point, the torque fluctuates in a certain range, and the fluctuation amplitude is small.

Corresponding to the above method embodiment, the embodiment of the invention also provides a speed limit control system of the new energy vehicle, and the speed limit control system of the new energy vehicle described below and the speed limit control method of the new energy vehicle described above can be referred to correspondingly.

Referring to fig. 7, a schematic structural diagram of a speed limit control system of a new energy vehicle according to the present invention includes:

the information acquisition module 701 is used for acquiring the motor rotating speed and the rotating speed change rate of the vehicle;

the first torque reduction triggering module 702 is configured to determine a value of a corresponding torque reduction coefficient and control the vehicle to enter a torque reduction state when it is determined that the rotation speed and the rotation speed change rate of the motor at the first time meet a preset first torque reduction triggering rule;

a torque reduction step calculation module 703, configured to calculate a torque change step according to the torque reduction coefficient;

a torque reduction adjustment module 704, configured to determine an actual torque at the current time to control the vehicle based on the determined actual torque by using the gear, the torque change step length, and the actual torque at the previous time of the vehicle at the current time, where an absolute value of the actual torque at the current time is lower than an absolute value of the actual torque at the previous time;

the first recovery module 705 is configured to, when it is determined that Δ Spd at the second time is greater than a preset first threshold, control the vehicle to exit from the transition state and enter a default state, so that an actual torque of the vehicle is equal to a target torque analyzed by an accelerator pedal, where Δ Spd is a difference between a target speed limit point and a motor rotation speed.

In one embodiment of the present invention, the method further comprises:

and the torque reduction transition triggering module is used for controlling the vehicle to exit the torque reduction state and enter the transition state when judging that the rotating speed and the rotating speed change rate of the motor at the third moment accord with a preset first transition triggering rule, and keeping the actual torque to be the same as the actual torque at the initial moment of entering the transition state in the transition state.

In one embodiment of the present invention, the method further comprises:

the torque-increasing triggering module is used for determining the value of the corresponding torque-increasing coefficient and controlling the vehicle to enter a torque-increasing state when the rotating speed and the rotating speed change rate of the motor at the fourth moment are judged to accord with the preset torque-increasing triggering rule;

the torque-increasing step length calculation module is used for calculating the torque change step length according to the torque-increasing coefficient;

the torque increasing adjusting module is used for determining the actual torque at the current moment by utilizing the gear of the vehicle at the current moment, the torque change step length and the actual torque at the previous moment, and the absolute value of the actual torque at the current moment is greater than that of the actual torque at the previous moment;

the torque-increasing transition triggering module is used for controlling the vehicle to exit the torque-increasing state and enter the transition state when judging that the rotating speed and the rotating speed change rate of the motor at the fifth moment accord with a preset second transition triggering rule, and keeping the actual torque to be the same as the actual torque at the initial moment when the torque-increasing state enters the transition state in the transition state;

the second recovery module is used for controlling the vehicle to exit from the torque-up state and enter the default state when the rotating speed and the rotating speed change rate of the motor at the fifth moment are judged to be not in accordance with the second transition triggering rule but delta Spd at the fifth moment is larger than the first threshold value, so that the actual torque of the vehicle is equal to the target torque analyzed by the accelerator pedal;

and the torque increasing maintaining module is used for keeping a torque increasing state when the rotating speed and the rotating speed change rate of the motor at the fifth moment are judged to be not in accordance with the second transition triggering rule and the delta Spd at the fifth moment is less than or equal to the first threshold value.

In one embodiment of the present invention, the method further comprises:

and the second torque reduction triggering module is used for controlling the vehicle to exit from the transition state and enter a torque reduction state when judging that the rotating speed and the rotating speed change rate of the motor at the sixth moment accord with a preset second torque reduction triggering rule, and the value of the torque reduction coefficient is a preset torque reduction regulation coefficient value after entering the torque reduction state.

In an embodiment of the present invention, the torsion reduction step calculation module 703 is specifically configured to:

determining the absolute value of delta Spd at the current moment;

and taking the product of the absolute value and the torque reduction coefficient as the calculated torque change step length.

In an embodiment of the present invention, the torque reduction adjustment module 704 is specifically configured to:

when the vehicle is in a forward gear, determining the actual torque at the current moment by using the difference value between the actual torque at the previous moment of the vehicle and the torque change step length;

when the vehicle is in a reverse gear, the actual torque at the current moment is determined by using the sum of the actual torque at the last moment of the vehicle and the torque change step length.

In one embodiment of the present invention, the torque reduction adjustment module 704, when calculating the actual torque of the forward gear, is specifically configured to:

In an embodiment of the present invention, the torsion reduction transition triggering module is specifically configured to:

In an embodiment of the present invention, the first torque down trigger module 702 is specifically configured to:

It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, 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 identical elements in a process, method, article, or apparatus that comprises the element.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

The principle and the implementation of the present invention are explained in the present application by using specific examples, and the above description of the embodiments is only used to help understanding the technical solution and the core idea of the present invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims

1. A speed limit control method of a new energy vehicle is characterized by comprising the following steps:

2. The speed limit control method of the new energy vehicle according to claim 1, wherein after determining the actual torque at the current moment to control the vehicle by using the gear position of the vehicle at the current moment, the torque change step size and the actual torque at the previous moment, before controlling the vehicle to exit the torque-down state and enter the default state, the method further comprises:

3. The speed limit control method of the new energy vehicle according to claim 2, characterized by further comprising, after the controlling the vehicle to exit the torque-down state and enter a transition state:

4. The speed limit control method of the new energy vehicle according to claim 2, characterized by further comprising, after the controlling the vehicle to exit the torque-down state and enter a transition state:

5. The speed limit control method of the new energy vehicle according to claim 1, wherein the calculating a torque change step size according to the torque reduction coefficient includes:

determining the absolute value of the delta Spd at the current moment;

6. The speed limit control method of the new energy vehicle according to claim 5, wherein the determining, using the gear position of the vehicle at the current time, the torque change step size, and the actual torque at the previous time, the actual torque at the current time to control the vehicle based on the determined actual torque, and the absolute value of the actual torque at the current time being lower than the absolute value of the actual torque at the previous time, comprises:

7. The speed limit control method of the new energy vehicle according to claim 6, wherein when the vehicle is in a forward gear, determining the actual torque at the current moment by using the difference between the actual torque at the moment on the vehicle and the torque change step size comprises:

8. The speed limit control method of the new energy vehicle according to claim 2, wherein when it is determined that the motor speed and the speed change rate at the third moment meet a preset first transition trigger rule, controlling the vehicle to exit the torque reduction state and enter a transition state comprises:

9. The speed-limiting control method of the new energy vehicle according to any one of claims 1 to 8, wherein when it is determined that the motor speed and the speed change rate at the first time meet a preset first torque reduction trigger rule, a value of a corresponding torque reduction coefficient is determined, and the vehicle is controlled to enter a torque reduction state, and the method includes:

10. A speed limit control system of a new energy vehicle is characterized by comprising: