CN111890946A - Electric vehicle motor auxiliary braking parking method and system - Google Patents

Electric vehicle motor auxiliary braking parking method and system Download PDF

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Publication number
CN111890946A
CN111890946A CN202010556845.4A CN202010556845A CN111890946A CN 111890946 A CN111890946 A CN 111890946A CN 202010556845 A CN202010556845 A CN 202010556845A CN 111890946 A CN111890946 A CN 111890946A
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motor
vehicle
torque
parking
calculating
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CN111890946B (en
Inventor
朱家东
张剑锋
陈继
宇文志强
王雪飞
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Zhejiang Geely Holding Group Co Ltd
Geely Automobile Research Institute Ningbo Co Ltd
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Zhejiang Geely Holding Group Co Ltd
Geely Automobile Research Institute Ningbo Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • B60L15/2009—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed for braking
    • B60L15/2018—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed for braking for braking on a slope
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/10—Vehicle control parameters
    • B60L2240/12—Speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/10—Vehicle control parameters
    • B60L2240/14—Acceleration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/42—Drive Train control parameters related to electric machines
    • B60L2240/423—Torque
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/42—Drive Train control parameters related to electric machines
    • B60L2240/425—Temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/60—Navigation input
    • B60L2240/64—Road conditions
    • B60L2240/642—Slope of road
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

The invention discloses an electric automobile motor auxiliary braking parking method and system, which detects whether an electronic parking system of a vehicle is effective when the vehicle is parked in a P gear, and adopts the motor auxiliary braking parking method if the electronic parking system of the vehicle is not effective, wherein the method comprises the following steps: acquiring the current rolling resistance and gradient resistance of the vehicle; calculating the feedforward torque of the motor according to the rolling resistance and the gradient resistance; acquiring the actual speed, the speed direction and the target speed of the vehicle; carrying out PI regulation on the motor torque and calculating PI regulation torque according to the difference value of the actual vehicle speed, the vehicle speed direction and the target vehicle speed; calculating to obtain a target motor torque according to the PI regulation torque and the feedforward torque; and the control motor outputs the target motor torque, and the target motor torque acts on the actual vehicle speed and the vehicle speed direction to realize closed-loop vehicle speed control. The auxiliary braking parking device can assist in braking parking when the electronic parking mechanism fails, and avoids potential safety hazards caused by unexpected slope sliding movement when a vehicle is parked on a slope.

Description

Electric vehicle motor auxiliary braking parking method and system
Technical Field
The invention relates to the technical field of electric automobile parking, in particular to an electric automobile motor auxiliary braking parking method and system.
Background
Conventional fuel-powered vehicles or hybrid vehicles are generally equipped with a transmission, and a parking lock mechanism is a safety device for preventing the vehicle from slipping in an automatic transmission, so that the vehicle can be parked reliably and without time limitation at a certain position even on a slope. Pure electric vehicles are not equipped with a gearbox, and currently, the following two solutions are generally available. One is to use an electronic parking mechanism instead of the function of a P-range lock, i.e. a parking range, i.e. the electronic parking mechanism is automatically locked when the user switches the gear lever to the P-range; another is to add other mechanical locking mechanisms, such as integrating a drive train lock inside the motor. Both of the above two solutions have certain disadvantages, wherein the solution using the electronic parking mechanism instead of the P-range lock can only lock the brake system, and when the external lines of the electronic control unit inside the electronic control transmission except the power supply line are damaged or the control device fails, it is difficult to perform parking brake at the driving position and keep the full-load vehicle prohibited on the upper and lower slopes with certain slopes, which may cause the vehicle to unexpectedly move along the slope, resulting in certain potential safety hazard. The scheme of adding other mechanical locking mechanisms avoids potential safety hazards to a certain degree, but directly increases the cost.
Disclosure of Invention
In order to solve the technical problem, the invention uses the motor to assist the braking parking on the basis of the electronic parking system so as to ensure that the vehicle can be normally parked under the condition that the electronic parking system is not normally started or fails, and unexpected slope sliding movement is avoided.
In order to achieve the above object, a first aspect of the present invention provides a motor-assisted braking parking method for an electric vehicle, which detects whether an electronic parking system of the vehicle is effective when the vehicle is parked in a P-range, and if not, adopts the motor-assisted braking parking method, and the motor-assisted braking parking method includes:
acquiring the current rolling resistance and gradient resistance of the vehicle;
calculating the feedforward torque of the motor according to the rolling resistance and the gradient resistance;
acquiring the actual speed, the speed direction and the target speed of the vehicle;
carrying out PI regulation on the motor torque and calculating PI regulation torque according to the difference value of the actual vehicle speed, the vehicle speed direction and the target vehicle speed;
calculating to obtain a target motor torque according to the PI regulation torque and the feedforward torque;
and the control motor outputs the target motor torque, and the target motor torque acts on the actual speed and the speed direction to realize closed-loop speed control so as to ensure that the vehicle normally stays on a slope under a certain slope.
Further, the obtaining the current gradient resistance of the vehicle comprises:
detecting the relative acceleration of the vehicle through a vehicle acceleration sensor;
calculating the absolute acceleration of the vehicle through the actual speed of the vehicle;
calculating to obtain a road slope value according to the relative acceleration and the absolute acceleration of the vehicle;
and calculating the slope resistance according to the road slope value.
Further, the motor auxiliary braking parking method further comprises the step of performing overheat protection on the motor when the motor outputs torque under the working condition that the rotating speed is zero for a long time, and the method for performing overheat protection on the motor comprises the following steps:
setting the maximum allowable motor parking time;
monitoring the motor parking time in real time;
and when the motor parking time is greater than or equal to the maximum allowable motor parking time, controlling the motor to smoothly unload the torque so as to reduce the temperature of the motor.
Further, the method for overheat protection of the motor further comprises:
monitoring the temperature of the motor in real time;
and when the temperature of the motor is greater than or equal to the preset safety temperature, controlling the motor to carry out torque smooth unloading so as to control the temperature of the motor to be less than the preset safety temperature.
Further, the method for protecting the motor from overheating further comprises the following steps: and when the motor parking time is monitored to be greater than or equal to the maximum allowable motor parking time or the motor temperature is monitored to be greater than the preset safety temperature, prompting a driver.
The invention also provides a motor-assisted braking parking system of an electric vehicle, comprising:
the first acquisition module is used for acquiring the current rolling resistance and gradient resistance of the vehicle;
the first calculation module is used for calculating the feedforward torque of the motor;
the second acquisition module is used for acquiring the actual vehicle speed, the vehicle speed direction and the target vehicle speed of the vehicle;
the PI regulation calculation module is used for carrying out PI regulation on the motor torque and calculating PI regulation torque;
the second calculation module is used for calculating to obtain the target motor torque;
and the control module is used for controlling the motor to output the target motor torque, and the target motor torque acts on the actual speed and the speed direction of the vehicle so as to ensure that the vehicle normally stops on a slope under a certain slope.
Further, the first obtaining module includes a slope resistance obtaining module that includes:
a relative acceleration acquisition unit for acquiring a relative acceleration of the vehicle;
an absolute acceleration acquisition unit for calculating an absolute acceleration of the vehicle;
the gradient value calculation unit is used for calculating to obtain a road gradient value;
and the gradient resistance calculating unit is used for calculating and obtaining the gradient resistance.
Further, the first obtaining module further comprises a motor overheat protection module, and the motor overheat protection module comprises:
the parking time setting module is used for setting the maximum allowable motor parking time;
the time monitoring module is used for monitoring the motor parking time in real time;
and the first temperature control module is used for controlling the motor to smoothly unload the torque when the motor parking time is greater than or equal to the maximum allowable motor parking time.
Further, the motor overheat protection module further includes:
the temperature monitoring module is used for monitoring the temperature of the motor in real time;
and the second temperature control module is used for controlling the motor to smoothly unload the torque when the temperature of the motor is greater than or equal to a preset safety temperature.
Further, the motor overheat protection module further includes:
and the motor overheating prompting unit is used for prompting a driver.
The embodiment of the invention has the following beneficial effects:
(1) when an electronic parking system of the vehicle cannot be started normally or fails, the vehicle is kept on the slope by the motor in a mode of generating certain negative torque according to the size of the slope under the working condition of descending the slope by utilizing the advantages of quick and accurate response and wide working range of the motor of the electric vehicle; and keeping the vehicle on the slope by a mode of a motor generating certain positive torque according to the size of the slope under the condition of uphill slope. Therefore, on the basis of not changing a hardware structure and not increasing cost, under the working condition of high-voltage electrification, the function of the mechanical locking mechanism is realized through the matching of an optimal software control algorithm and fine calibration, and the safety risk is reduced to a certain extent.
(2) The motor auxiliary braking parking method of the invention comprehensively calculates the current rolling resistance and gradient resistance of the vehicle to obtain the motor feedforward torque. And then, according to the actual performance of the vehicle, including the actual speed and the speed direction of the vehicle, PI real-time regulation is carried out on the motor torque, so that closed-loop control is formed, when the vehicle is accelerated or decelerated unexpectedly forwards or backwards due to the calculation error of the feedforward torque, adjustment can be timely made, and the vehicle can be ensured to normally stay on a slope under a certain slope.
Drawings
In order to more clearly illustrate the method, the system and the automobile for controlling the vehicle neutral flameout coasting condition of the present invention, the drawings required for the embodiments will be briefly introduced 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 schematic flow chart of a method for parking an electric vehicle through auxiliary braking of a motor according to embodiment 1 of the present invention;
FIG. 2 is a flowchart of calculating a road grade value using an acceleration sensor according to embodiment 1 of the present invention;
FIG. 3 is a logic diagram of the feedforward plus closed-loop control of the motor assisted brake parking method according to embodiment 1 of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or server that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Examples
The embodiment of the invention provides an electric vehicle motor auxiliary braking parking method which is used for detecting whether an electronic parking system of a vehicle is effective or not when the vehicle is parked in a P gear, and if not, the motor auxiliary braking parking method is adopted to assist parking, so that unsafe accidents are avoided. As shown in fig. 1, the motor-assisted brake parking method includes:
and S01, acquiring the current rolling resistance and gradient resistance of the vehicle. Specifically, in the embodiment of the present invention, the obtaining of the current gradient resistance of the vehicle includes:
s011, detecting the relative acceleration of the vehicle through a vehicle acceleration sensor;
s012, calculating the absolute acceleration of the vehicle according to the actual speed of the vehicle;
s013, calculating a road slope value according to the relative acceleration and the absolute acceleration of the vehicle;
and S014, calculating the slope resistance according to the road slope value.
Specifically, the acceleration of the vehicle, which can be detected by the acceleration sensor, is a relative acceleration of the vehicle, an absolute acceleration of the vehicle can be calculated according to an actual vehicle speed of the vehicle, and a road grade value can be calculated by a difference between the two accelerations.
As shown in FIG. 2, a flow chart for calculating a road grade value using an acceleration sensor, a relative acceleration obtained by filtering a signal of the acceleration sensor through a low pass filter, an absolute acceleration obtained by processing a signal of a vehicle speed measured by a vehicle speed sensor, and a difference between the two accelerations divided by a gravitational acceleration is showngAnd calculating to obtain the road slope value. When the vehicle goes up or down a slope, the acceleration is transmittedThe sensor measures the absolute acceleration of the vehicle plus the component of the gravitational acceleration parallel to the road surface, which is expressed by the relation:
asen＝a+g sinθ
in the formula asenAcceleration values (relative accelerations) measured by an acceleration sensor, m/s2。
a-vehicle acceleration (absolute acceleration), m/s2。
g-acceleration of gravity, m/s2。
Theta-road bank angle, °.
The road slope α may be calculated using the following equation:
Figure BDA0002544616760000061
calculating gradient resistance:
F＝Gsinθ
where G is the gravity acting on the vehicle, G is mg, m is the vehicle mass, G is the acceleration of gravity, θ is the road slope angle, (conversion α of the slope angle and the road slope α is tan θ).
Specifically, in the embodiment of the invention, the current rolling resistance of the vehicle is obtained, and the rolling resistance is calculated according to the wheel load and the rolling resistance coefficient. Rolling resistance is only used when vehicle speed is generated because there is no normal parking.
Calculation of rolling resistance:
F＝Wf
wherein, W is wheel load, f is rolling resistance coefficient, because the rolling resistance coefficient is relatively complicated and related to vehicle speed, road surface type, tire material inflation pressure, etc., generally do not do direct calculation, carry on the calibration of real vehicle and look up the table through the vehicle speed and obtain.
And S03, calculating the feed-forward torque of the motor according to the rolling resistance and the gradient resistance.
And S05, acquiring the actual vehicle speed, the vehicle speed direction and the target vehicle speed of the vehicle.
Specifically, in practical application, the actual speed and the speed direction of the vehicle can be accurately detected through a wheel speed sensor which is independently equipped with four wheels, and the information is fed back to a PI adjusting module to carry out closed-loop control on the torque of the motor. The target vehicle speed is a vehicle speed after the vehicle is parked, and is generally set to 0.
And S07, carrying out PI regulation on the motor torque and calculating PI regulation torque according to the difference value of the actual vehicle speed, the vehicle speed direction and the target vehicle speed.
And S09, calculating to obtain a target motor torque according to the PI regulation torque and the feedforward torque.
Specifically, the target motor torque is a motor torque required by the vehicle for retaining on the slope, and the vehicle is retained on the slope in a mode of generating a certain negative torque by the motor according to the size of the slope under the working condition of descending the slope; and when the vehicle is in an uphill working condition, the vehicle is kept on a slope by a mode that the motor generates certain positive torque according to the size of the slope. PI regulation is carried out by comparing the difference value of the target vehicle speed and the actual vehicle speed, and then the PI regulation torque after PI regulation and the feedforward torque are used for comprehensively calculating the target motor torque, so that a vehicle speed closed loop (0 vehicle speed parking closed loop) is realized by controlling the motor torque. In the embodiment of the present invention, the PI regulation refers to proportional integral control, that is, PI control.
And S11, controlling the motor to output the target motor torque, wherein the target motor torque acts on the actual speed and the speed direction, and realizing closed-loop speed control to ensure that the vehicle normally stops on a slope under a certain slope.
Specifically, the motor assisted brake parking method further comprises: when the motor outputs torque under the working condition that the rotating speed is zero for a long time, the motor is subjected to overheat protection,
the method for overheat protection of the motor comprises the following steps:
s101, setting the maximum allowable motor parking time;
s103, monitoring the parking time of the motor in real time;
and S105, when the motor parking time is greater than or equal to the maximum allowable motor parking time, controlling the motor to smoothly unload the torque so as to reduce the temperature of the motor.
Specifically, the method for overheat protection of the motor further comprises the following steps:
s107, monitoring the temperature of the motor in real time;
and S109, when the temperature of the motor is greater than or equal to the preset safety temperature, controlling the motor to carry out torque smooth unloading so as to control the temperature of the motor to be less than the preset safety temperature.
In particular, since the motor outputs a torque under a condition where the rotational speed is zero for a long time, there is an increased risk of overheating, and thus, overheating protection of the motor is required. Firstly, a rack locked-rotor temperature rise test is carried out on the motor, the maximum allowable locked-rotor time of the motor is tested under the working conditions of the same rotating speed and different torques, the maximum allowable motor parking time is set according to the motor torque, and a certain margin can be reserved for the maximum allowable motor parking time to prevent overheating. When the motor auxiliary parking function is adopted, the parking time of the motor exceeds the maximum allowable motor parking time, the motor torque is controlled to be unloaded so as to reduce the temperature of the motor, and the overheating damage is prevented.
In addition, the temperature of the motor is monitored in real time in the process, the system for controlling the temperature of the motor to be too high can automatically limit the torque output of the engine, and the problem that the power is suddenly lost to cause the vehicle to slide along an unexpected slope is likely to occur, so that the temperature of the motor is controlled to be lower than a preset safety temperature, wherein the preset safety temperature is a preset temperature threshold value which is before the torque limit point of the motor and is used for preventing the motor from being damaged due to overheating. And when the temperature of the motor is more than or equal to the preset safe temperature, controlling the motor to carry out torque smooth unloading so as to reduce the temperature of the motor.
Specifically, the method for protecting the motor from overheating further comprises the following steps: and when the motor temperature is monitored to be higher than the preset safety temperature, prompting a driver. Specifically, because of the risk of motor overheating, the state of the function needs to be informed to the driver in real time, and the driver is reminded to step on the brake to prevent unexpected slope slip before the motor is overheated to unload the torque.
In the embodiment of the invention, the motor parking function is an auxiliary braking parking function of the automobile, and the function is started only after the electronic parking system fails, so that before the function is activated, a driver is informed that the parking system fails, normal parking on a slope cannot be carried out, and maintenance needs to be carried out as soon as possible. Specifically, as shown in fig. 3, the logic block diagram of feedforward plus closed-loop control is shown, when a driver actively switches a shift lever to a P-range parking range, if it is detected that an electronic parking system of the vehicle is disabled at the time, a motor parking function is directly activated, that is, a motor assisted braking parking method is adopted, and at the time, the parking system comprehensively calculates current rolling resistance and gradient resistance to obtain a motor feedforward torque. And then, according to the actual performance of the vehicle, including the current actual speed and the speed direction of the vehicle, PI real-time regulation is carried out on the motor torque, so that closed-loop control is formed, when the vehicle is accelerated or decelerated unexpectedly forwards or backwards due to the calculation error of the feedforward torque, adjustment can be timely made, and the vehicle can be ensured to normally stay on a slope under a certain slope.
Example 2
Embodiment 2 of the present invention provides an electric vehicle motor auxiliary braking parking system, where the electric vehicle motor auxiliary braking parking system is configured to configure the parking method according to embodiment 1, and the electric vehicle motor auxiliary braking parking system includes:
the first acquisition module is used for acquiring the current rolling resistance and gradient resistance of the vehicle;
the first calculation module is used for calculating the feedforward torque of the motor;
the second acquisition module is used for acquiring the actual vehicle speed, the vehicle speed direction and the target vehicle speed of the vehicle;
the PI regulation calculation module is used for carrying out PI regulation on the motor torque and calculating PI regulation torque;
the second calculation module is used for calculating to obtain the target motor torque;
and the control module is used for controlling the motor to output the target motor torque, and the target motor torque acts on the actual speed and the speed direction of the vehicle so as to ensure that the vehicle normally stops on a slope under a certain slope.
Specifically, the first obtaining module includes a gradient resistance obtaining module that includes:
a relative acceleration acquisition unit for acquiring a relative acceleration of the vehicle;
an absolute acceleration acquisition unit for calculating an absolute acceleration of the vehicle;
the gradient value calculation unit is used for calculating to obtain a road gradient value;
and the gradient resistance calculating unit is used for calculating and obtaining the gradient resistance.
Specifically, the first obtaining module further includes a motor overheat protection module, and the motor overheat protection module includes:
the parking time setting module is used for setting the maximum allowable motor parking time;
the time monitoring module is used for monitoring the motor parking time in real time;
and the first temperature control module is used for controlling the motor to smoothly unload the torque when the motor parking time is greater than or equal to the maximum allowable motor parking time.
Specifically, the motor overheat protection module further includes:
the temperature monitoring module is used for monitoring the temperature of the motor in real time;
and the second temperature control module is used for controlling the motor to smoothly unload the torque when the temperature of the motor is greater than or equal to a preset safety temperature.
Specifically, the motor overheat protection module further includes:
and the motor overheating prompting unit is used for prompting a driver.
It should be noted that: the precedence order of the above embodiments of the present invention is only for description, and does not represent the merits of the embodiments. And specific embodiments thereof have been described above. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the device and server embodiments, since they are substantially similar to the method embodiments, the description is simple, and the relevant points can be referred to the partial description of the method embodiments.
It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, and the program may be stored in a computer-readable storage medium, which may be a read-only memory, a magnetic or optical disk, or the like.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims (10)

1. The motor-assisted braking parking method for the electric automobile is characterized in that when the automobile is parked in a P gear, whether an electronic parking system of the automobile is effective is detected, and if not, the motor-assisted braking parking method is adopted, and the motor-assisted braking parking method comprises the following steps:
acquiring the current gradient resistance and rolling resistance of the vehicle;
calculating the feedforward torque of the motor according to the gradient resistance and the rolling resistance;
acquiring the actual speed and the speed direction of the vehicle;
carrying out PI regulation on the motor torque and calculating PI regulation torque according to the difference value of the actual vehicle speed, the vehicle speed direction and the target vehicle speed;
calculating to obtain a target motor torque according to the PI regulation torque and the feedforward torque;
and the control motor outputs the target motor torque, and the target motor torque acts on the actual speed and the speed direction to realize closed-loop speed control so as to ensure that the vehicle normally stays on a slope under a certain slope.
2. The method of claim 1, wherein the step of obtaining the current gradient resistance of the vehicle comprises:
detecting the relative acceleration of the vehicle through a vehicle acceleration sensor;
calculating the absolute acceleration of the vehicle through the actual speed of the vehicle;
calculating to obtain a road slope value according to the relative acceleration and the absolute acceleration of the vehicle;
and calculating the slope resistance according to the road slope value.
3. The method for parking the electric vehicle through the motor-assisted brake of the claim 1, characterized in that the method for parking the electric vehicle through the motor-assisted brake further comprises the step of protecting the motor from overheating when the motor outputs the torque under the condition that the rotating speed of the motor is zero for a long time, and the method for protecting the motor from overheating comprises the following steps:
setting the maximum allowable motor parking time;
monitoring the motor parking time in real time;
and when the motor parking time is greater than or equal to the maximum allowable motor parking time, controlling the motor to smoothly unload the torque so as to reduce the temperature of the motor.
4. The electric vehicle motor-assisted brake parking method according to claim 3, wherein the method for overheat protecting the motor further comprises:
monitoring the temperature of the motor in real time;
and when the temperature of the motor is greater than or equal to a preset safety temperature, controlling the motor to carry out torque smooth unloading so as to control the temperature of the motor to be less than the preset safety temperature.
5. The electric vehicle motor-assisted brake parking method of claim 4, wherein the method for protecting the motor from overheating further comprises:
and when the motor parking time is monitored to be greater than or equal to the maximum allowable motor parking time or the motor temperature is monitored to be greater than the preset safety temperature, prompting a driver.
6. The utility model provides an electric automobile motor assisted brake parking system which characterized in that includes:
the first acquisition module is used for acquiring the current rolling resistance and gradient resistance of the vehicle;
the first calculation module is used for calculating the feedforward torque of the motor;
the second acquisition module is used for acquiring the actual vehicle speed, the vehicle speed direction and the target vehicle speed of the vehicle;
the PI regulation calculation module is used for carrying out PI regulation on the motor torque and calculating PI regulation torque;
the second calculation module is used for calculating to obtain the target motor torque;
and the control module is used for controlling the motor to output the target motor torque, and the target motor torque acts on the actual speed and the speed direction of the vehicle so as to ensure that the vehicle normally stops on a slope under a certain slope.
7. The electric vehicle motor-assisted brake parking system of claim 6, wherein the first obtaining module comprises a gradient resistance obtaining module comprising:
a relative acceleration acquisition unit for acquiring a relative acceleration of the vehicle;
an absolute acceleration acquisition unit for calculating an absolute acceleration of the vehicle;
the gradient value calculation unit is used for calculating to obtain a road gradient value;
and the gradient resistance calculating unit is used for calculating and obtaining the gradient resistance.
8. The electric vehicle motor-assisted brake parking system of claim 6, wherein the first obtaining module further comprises a motor overheating protection module, and the motor overheating protection module comprises:
the parking time setting module is used for setting the maximum allowable motor parking time;
the time monitoring module is used for monitoring the motor parking time in real time;
and the first temperature control module is used for controlling the motor to smoothly unload the torque when the motor parking time is greater than or equal to the maximum allowable motor parking time.
9. The electric vehicle motor-assisted brake parking system of claim 8, wherein the motor overheat protection module further comprises:
the temperature monitoring module is used for monitoring the temperature of the motor in real time;
and the second temperature control module is used for controlling the motor to smoothly unload the torque when the temperature of the motor is greater than or equal to a preset safety temperature.
10. The electric vehicle motor-assisted brake parking system of claim 8, wherein the motor overheat protection module further comprises:
and the motor overheating prompting unit is used for prompting a driver.
CN202010556845.4A 2020-06-17 2020-06-17 Electric vehicle motor auxiliary braking parking method and system Active CN111890946B (en)

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