CN110745011A

CN110745011A - Slope parking method for pure electric vehicle

Info

Publication number: CN110745011A
Application number: CN201911321819.7A
Authority: CN
Inventors: 鲁克银; 鲍旭文; 韩黎
Original assignee: SHANGHAI LECKON ELECTRICAL TECHNOLOGY Co Ltd
Current assignee: SHANGHAI LECKON ELECTRICAL TECHNOLOGY Co Ltd
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2020-02-04
Anticipated expiration: 2039-12-20
Also published as: CN110745011B

Abstract

The invention provides a pure electric vehicle slope parking method which is characterized by comprising the following steps of slope parking state judgment: judging whether the vehicle is in a slope slipping state or not, obtaining a judgment result that the vehicle is in the slope slipping state or not, and if the judgment result is that the vehicle is in the non-slope slipping state, terminating the process or entering a set subsequent step; and (3) slope-stopping torque initialization: if the judgment result is that the vehicle is in a slope slipping state, initializing slope stopping torque according to the current rotating speed n; a torque change gradient determination step: after the hill-holding torque is initialized, different torque change gradients δ Trq are set according to the current motor speed n and the actual output torque at that time. The electric automobile slope-parking method provided by the invention has the advantages of simple logic structure and high reliability.

Description

Slope parking method for pure electric vehicle

Technical Field

The invention relates to the technical field of electric vehicle control, in particular to a pure electric vehicle slope parking method.

Background

When a pure electric automobile runs on a slope, if the pure electric automobile needs to be parked and frequently started and stopped when the pure electric automobile runs in a traffic jam or a red light, the pure electric automobile can slide down the slope due to the gravity of the pure electric automobile. In order to improve driving comfort, consistency and prevent the vehicle from sliding down the slope when a driver operates improperly, a large number of pure electric vehicles are added with a slope-stopping function.

A conventional slope parking device, such as an electric vehicle parking device disclosed in patent document CN107618486A, is configured to lock a driving axle of an electric vehicle during parking, and includes a transmission system and a support plate, the transmission system is disposed on the support plate, an output end of the transmission system is a push rod, the push rod passes through a waist hole in the support plate and can swing left and right along the waist hole, a sliding groove is disposed at a bottom of the push rod, the device further includes a locking mechanism, the locking mechanism is disposed below the support plate, a positioning mechanism is fixed on a lower end surface of the support plate, and the positioning mechanism can position the locking mechanism to achieve accurate locking of the driving axle

The existing slope-retaining method comprises the following steps:

1. the vehicle control unit judges whether the vehicle has backward slip phenomenon or not according to the gear signal and the vehicle speed, and then directly switches from torque loop control to rotating speed loop zero speed control. In the method, the control and adjustment time of the rotating speed loop is long, so that the backward sliding distance of the vehicle is long, and danger is easy to occur;

2. and the vehicle controller judges the backward sliding working condition according to the gear signal and the vehicle speed, and multiplies the last output torque of the motor before backward sliding by a certain coefficient to serve as a control initial value of a rotating speed loop. Although the control mode increases the corresponding time of the speed ring, the parameter adaptability is not strong, the control mode cannot adapt to various working conditions of the front slope, the middle slope and the top slope, and vehicle shaking is easy to generate in the adjusting process;

therefore, the pure electric vehicle slope parking method is high in value and significance.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a pure electric vehicle slope parking method.

The pure electric vehicle slope-parking method provided by the invention comprises a slope-parking state judgment step, a slope-parking torque initialization step and a torque change gradient determination step;

and (3) judging the state of the standing slope: judging whether the vehicle is in a slope slipping state or not, obtaining a judgment result that the vehicle is in the slope slipping state or not, and if the judgment result is that the vehicle is in the non-slope slipping state, terminating the process or entering a set subsequent step;

and (3) slope-stopping torque initialization: if the judgment result is that the vehicle is in a slope slipping state, initializing slope stopping torque according to the current rotating speed n;

a torque change gradient determination step: after the hill-holding torque is initialized, different torque change gradients δ Trq are set according to the current motor speed n and the actual output torque at that time.

Preferably, the pure electric vehicle hill-holding method further comprises a hill-holding torque locking step, a zero-speed locking state judging step, a torque loop step, a rotating speed loop step and a hill-holding mode exiting step;

and a hill-holding torque locking step: primarily locking initial hill-holding torque Trq _ F according to the current motor rotating speed n and the rotating speed variable quantity delta n;

a zero-speed locking state judgment step: judging whether Trq _ F is greater than Trq _1 or not through the locked Trq _ F, if Trq _ F is less than or equal to Trq _1, entering a torque loop step, and if Trq _ F is greater than Trq _1, entering a rotating speed loop step;

wherein, Trq _1 is a torque set value and is related to vehicle parameters;

a torque loop step: if Trq _ F is less than or equal to Trq _1, the torque ring operates with the torque Trq _ F, and the Trq _ F is corrected according to the current motor rotating speed n so as to ensure that the motor rotating speed does not shake back and forth in the zero rotating speed locking stage and further improve the comfort of the vehicle;

rotating speed looping: if Trq _ F is larger than Trq1, assigning Trq _ F K to an initial value of the rotating speed ring integral quantity to carry out rotating speed ring zero rotating speed operation;

k is an empirical coefficient adjusted through actual calibration;

exiting the hill-holding mode: and if the running time t of the torque loop step or the rotating speed loop step is more than 15s, or the foot brake and hand brake signals become effective, exiting the hill-holding mode.

Preferably, in the step of determining the parking state, the specific determination method is that the MCU determines whether the vehicle hand brake signal and the foot brake signal are invalid, and if both are invalid, determines whether the rotation direction of the motor is opposite to the rotation direction of the motor when the vehicle is moving forward, and if so, determines that the vehicle is in a slope slipping state and enters a parking mode, otherwise, determines that the vehicle is in a non-slope slipping state.

Preferably, in the hill-holding torque initializing step, the hill-holding torque is larger as the negative rotation speed of the motor is larger.

Preferably, in the torque variation gradient determining step, the larger the motor negative rotation speed n and the larger the motor output torque, the larger the corresponding δ Trq value.

Preferably, in the hill-holding torque locking step, hill-holding torque Trq _ F is set in a segmented manner according to the current rotation speed n and the rotation speed variation δ n, and the setting of Trq _ F is obtained through empirical estimation and actual sample vehicle calibration.

Preferably, in the rotating speed ring step, in the zero rotating speed operation process of the rotating speed ring, if the rotating speed of the motor has a forward rush or backward slip phenomenon, that is, the absolute value | n | ≧ n1 of the rotating speed n, the rotating speed ring output torque is directly adjusted; if | n | < n1, still operating at the rotating speed PI ring;

the PI parameter of the PI regulator here is an empirical value obtained by long-term motor control.

Preferably, the pure electric vehicle comprises a vehicle control unit VCU and a motor controller MCU; in the step of exiting the hill-holding mode, if a torque command Trq _ cmd sent by the VCU of the vehicle controller to the MCU is greater than a comparison value, exiting the hill-holding mode;

the comparison value is the sum of the actual output torque Trq _ Fdb of the motor and the set value.

Preferably, the pure electric vehicle comprises a vehicle control unit VCU and a motor controller MCU; and in the step of judging the slope state, judging whether the vehicle is in a slope slipping state or not through the motor controller MCU.

a torque change gradient determination step: after initializing the hill-holding torque, setting different torque change gradients delta Trq according to the current motor rotating speed n and the current actual output torque;

the pure electric vehicle hill-holding method further comprises a hill-holding torque locking step, a zero-speed locking state judging step, a torque loop step, a rotating speed loop step and a hill-holding mode exiting step;

wherein, Trq _1 is a torque set value and is related to vehicle parameters;

k is an empirical coefficient adjusted through actual calibration;

exiting the hill-holding mode: if the running time t of the torque loop step or the rotating speed loop step is more than 15s, or the signals of a foot brake and a hand brake become effective, the hill-holding mode is exited;

in the step of determining the parking state, the specific determination method is that the MCU determines whether the hand brake signal and the foot brake signal of the vehicle are invalid, if both are invalid, the MCU determines whether the rotation direction of the motor is opposite to the rotation direction of the motor when the vehicle advances, if the rotation directions are opposite and the rotation speed n is less than-6 r/min, the MCU determines that the vehicle is in a slope slipping state and enters a parking mode, and if not, the MCU determines that the vehicle is in a non-slope slipping state;

in the step of initializing the hill-holding torque, the greater the negative rotating speed of the motor is, the greater the hill-holding torque is;

in the step of determining the torque change gradient, if the negative rotating speed n of the motor is larger and the output torque of the motor is larger, the corresponding delta Trq value is larger;

in the step of locking the hill-holding torque, the hill-holding torque Trq _ F is set in a segmented mode according to the current rotating speed n and the rotating speed variable quantity delta n, and the setting of the Trq _ F is obtained through empirical estimation and actual sample vehicle calibration;

in the rotating speed ring step, in the zero rotating speed running process of the rotating speed ring, if the rotating speed of the motor has a forward rush or backward slip phenomenon, namely the absolute value | n | of the rotating speed n is more than or equal to n1, directly adjusting the output torque of the rotating speed ring; if | n | < n1, still operating at the rotating speed PI ring;

the PI parameter of the PI regulator is an empirical value obtained through long-term motor control;

the pure electric vehicle comprises a vehicle control unit VCU and a motor controller MCU; in the step of exiting the hill-holding mode, if a torque command Trq _ cmd sent by the VCU of the vehicle controller to the MCU is greater than a comparison value, exiting the hill-holding mode;

the comparison value refers to the sum of the actual output torque Trq _ Fdb of the motor and a set value;

the pure electric vehicle comprises a vehicle control unit VCU and a motor controller MCU; and in the step of judging the slope state, judging whether the vehicle is in a slope slipping state or not through the motor controller MCU.

Compared with the prior art, the invention has the following beneficial effects:

1. the electric automobile slope-parking method provided by the invention has the advantages of simple logical structure and high reliability;

2. the electric automobile slope-parking method provided by the invention has the advantages that the whole process is controlled and completed by the MCU (motor controller), the slope-parking function is rapidly completed under the condition that the automobile slips down on a slope, the power consumption is reduced by using better output torque, the adjustment is rapid in the whole slope-parking process, the automobile does not shake, the slope starting after slope parking is coherent and comfortable, the safety and the comfort of the slope driving of the automobile are improved, the power output of the driving motor and the motor controller is reduced, the energy consumption is saved, and the service lives of the motor and the motor controller are prolonged;

3. compared with the prior art, the electric automobile slope parking method has the advantages that the whole slope sliding prevention stage is divided into torque loop control and rotating speed loop control by the strategy, the vehicle backward sliding trend is quickly slowed down by certain slope parking torque, in addition, in order that the vehicle does not have uncomfortable feelings such as jitter, pause and the like in the stage, the output torque of the motor is subjected to smooth processing, the torque is set and corrected according to the real-time motor rotating speed change trend and the motor rotating speed, and the comfort level of the vehicle in the slope parking process is increased and is correspondingly quicker due to the fact that the torque processing is subdivided according to different working conditions. The method can rapidly prevent the vehicle from rolling backwards with relatively small output torque, and can reduce power consumption and reduce the heat generation of the motor when the vehicle is parked on the slope with relatively small output torque because the output torque in the slope parking process is large.

Drawings

Other features, objects and advantages of the present invention will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, with reference to the accompanying drawings.

Fig. 1 is a flow chart of a fast hill-holding method according to an embodiment of the present invention.

Fig. 2 is a control flow chart of the fast hill-holding mode.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

wherein, Trq _1 is a torque set value and is related to vehicle parameters;

k is an empirical coefficient adjusted through actual calibration;

Further, the terms related to the present invention are explained as follows:

the VCU is a finished automobile control unit, and a pure electric automobile finished automobile Controller (Vehicle Controller) is a core component of a pure electric automobile finished automobile control system, and plays a key role in the functions of normal running, regenerative energy recovery, network management, fault diagnosis and treatment, Vehicle state and monitoring and the like of an automobile.

The motor control unit is mainly integrated with two parts, namely a motor and an inverter, and is mainly used for controlling the power output and the capability brake recovery of the motor according to the input of an accelerator pedal and a brake pedal (given instructions by a VCU).

The invention preferably provides a quick slope-parking method for a pure electric vehicle, which can finish quick and stable slope parking with relatively small output torque.

The preferred method of the invention comprises the following steps:

1. the MCU (motor controller) judges whether the rotating speed direction of the motor is opposite to the advancing direction and the rotating speed is less than-6 r/min, and simultaneously judges whether a vehicle foot brake signal and a hand brake signal are invalid at the moment;

2. initializing the hill-holding torque according to the motor rotating speed acquired in real time, correcting the torque change gradient according to the rotating speed and the output torque, estimating the climbing gradient according to the rotating speed and the rotating speed variation, primarily locking the hill-holding torque, and finely adjusting the primarily locked hill-holding torque according to the rotating speed to obtain the final hill-holding torque Trq _ F;

3. after the hill-holding torque Trq _ F obtained in the step 2 is multiplied by a certain coefficient to be close to 1, the output torque of the rotating speed ring is assigned

And (5) carrying out 0-speed rotating speed loop operation on the initial value of the position type PI integral quantity. When the rotating speed ring is in closed-loop control, corresponding processing is carried out according to the rotating speed of the motor so as to solve the phenomena of forward rush, backward slip and shaking of the vehicle in the process of slope parking;

4. and when the foot brake and hand brake signals of the vehicle are effective or a torque instruction sent to the MCU by a VCU (vehicle control unit) is larger than the current motor output torque in the slope stopping process, the vehicle exits the slope stopping mode when any one of the conditions is met. When the hill-holding time is more than 15S, the hill-holding mode is exited, and the vehicle rolls back at a constant speed;

further, the steps of the preferred embodiment of the present invention are described below with reference to the accompanying drawings.

Step 1: referring to fig. 1, a MCU (motor controller) determines whether a vehicle is in a slope slipping state, and the specific method is that the MCU determines whether a hand brake signal and a foot brake signal of the vehicle are invalid, if both are invalid, determines whether a motor rotation direction is opposite to a motor rotation direction when the vehicle is moving forward, and if both are invalid and a rotation speed n is less than-6 r/min, determines that the vehicle is in a slope slipping state, and enters a slope parking mode.

Step 2: entering a hill-holding mode, and initializing hill-holding torque according to the current rotating speed n. When the negative rotating speed of the motor is larger, the slope slipping condition is obvious at the moment, and the required slope stopping torque is larger.

And step 3: different torque change gradients delta Trq are set according to the current motor rotating speed n and the actual output torque at the moment, and when the motor negative rotating speed n is larger and the motor output torque is larger, the corresponding set delta Trq is larger, so that the final slope-stopping torque Trq _ F is ensured to be locked quickly, and slope stopping is finished quickly. Meanwhile, the section delta Trq according to the motor speed and the output torque can ensure that the vehicle does not shake in the slope parking process.

The method obtained in the step 2 and the step 3 can enable the output torque of the motor to be relatively small, reduce the power output of the motor, reduce the consumption of the electric quantity of the battery and reduce the heating of the motor.

And 4, step 4: and locking the initial hill-holding torque Trq _ F preliminarily according to the current motor rotating speed n and the rotating speed variable quantity delta n. The hill-holding torque Trq _ F is set in stages according to the current rotation speed and the rotation speed variation δ n. The Trq _ F setting is obtained by empirical estimation and actual sample vehicle calibration.

And 5: and (4) judging whether Trq _ F > Trq1 is satisfied or not through the Trq _ F locked in the step 4, and determining whether the zero-speed locking stage enters a torque ring or a rotating speed ring to operate.

Step 6: if Trq _ F < Trq _1, the torque loop is operated with a torque Trq _ F, which is modified according to the current motor speed n to ensure that the motor speed does not flutter back and forth during the zero speed lock phase to increase vehicle comfort.

And 7: and if Trq _ F is larger than Trq1, enabling Trq _ F K (K is an empirical coefficient) to be close to 1 assigned rotation speed ring integral quantity initial value, and carrying out rotation speed ring zero rotation speed operation. When the rotating speed of the rotating speed ring runs at zero rotating speed, if the rotating speed of the motor has the phenomenon of forward rush or backward slip, namely the absolute value | n | of the rotating speed n is more than n1, the output torque of the rotating speed ring is directly adjusted; if | n | < n1, the rotating speed PI ring is still operated.

And 8: exiting the hill-holding mode: and (4) when the running time t of the step 6 or the step 7 is more than 15s, or any one of the following conditions is met in the hill-holding process, the hill-holding mode is exited, the vehicle rolls back at a constant speed until the driver presses an accelerator pedal or a brake pedal, and the hill-holding mode is entered again if the condition of the step 1 is met. The exit conditions include: in the hill-holding process, the foot brake and hand brake signals are effective, a torque command (Trq _ cmd) sent to the MCU by the VCU (vehicle control unit) is greater than the actual output torque (Trq _ Fdb) of the motor, and the specific judgment formula is as follows: trq _ cmd > Trq _ Fdb +10 (N.m)

The invention can quickly and stably complete the slope parking function when the pure electric vehicle runs on a slope and the vehicle condition is met. The control strategy firstly judges whether a slope slipping working condition exists or not, judges whether all conditions of the slope slipping prevention strategy are met or not, and enters a slope slipping prevention mode if the conditions are met. Compared with the prior art, the strategy has the advantages that the whole slope slipping prevention stage is divided into torque loop control and rotating speed loop control, the vehicle backward slipping trend is quickly slowed down by certain slope-staying torque, and the output torque of the motor is subjected to smoothing treatment so that the vehicle does not have uncomfortable feelings such as shaking and pause in the stage. The torque is set and corrected according to the real-time motor rotating speed change trend and the motor rotating speed, and the comfort degree of the vehicle in the slope parking process is increased and is correspondingly faster due to the fact that the torque is processed according to different working conditions. The method can rapidly prevent the vehicle from rolling backwards with relatively small output torque, and can reduce power consumption and reduce the heat generation of the motor when the vehicle is parked on the slope with relatively small output torque because the output torque in the slope parking process is large.

In a preferred embodiment of the invention, K is an empirical coefficient with a value close to 1;

zero speed closed loop control, where incremental PI (proportional-integral) control is used.

The incremental PI control, a basic form of a digital PI control algorithm, is a control algorithm that performs PI control on an increment of a controlled variable (a difference between a current controlled variable and a previous controlled variable). The control amount of the speed loop is an error between the desired rotational speed and the actual rotational speed, and PI control is performed by an increment of the error.

Err=Spd_Cmd – Spd_Act

Err error

Spd _ Cmd desired speed

Spd _ Act actual value of rotation speed

Δerr= Err_k– Err_k-1

Delta err error delta

Err_kError in the period

Err_k-1: error of previous cycle

Used herein is a position-based control algorithm recursive calculation formula that is recursive through an incremental control algorithm

u_k=u_k-1+δu_k

In the formula u_kFor output of control torque u for speed loop_k-1For the output torque of the preceding control cycle, δ u_kThe increment of the control amount is output for the incremental PI.

The initial value of the integral amount described in the claims refers to an initial torque output value at the time of entering the speed loop control.

The PI parameter of the PI regulator is an empirical value obtained through long-term motor control, and the PI parameter can be adjusted through testing aiming at motors of different models.

In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims

1. A pure electric vehicle hill-holding method is characterized by comprising a hill-holding state judging step, a hill-holding torque initializing step and a torque change gradient determining step;

wherein, Trq _1 is a torque set value and is related to vehicle parameters;

k is an empirical coefficient adjusted through actual calibration;

2. The pure electric vehicle slope parking method according to claim 1, wherein in the slope parking state determining step, the specific determining method is that the MCU determines whether the vehicle hand brake signal and the foot brake signal are invalid, if both are invalid, determines whether the motor rotation direction is opposite to the motor rotation direction when the vehicle is moving forward, if so, determines that the vehicle is in a slope slipping state and enters a slope parking mode, otherwise, determines that the vehicle is in a non-slope slipping state.

3. The pure electric vehicle hill-holding method according to claim 1, characterized in that in the hill-holding torque initialization step, the greater the negative rotation speed of the motor, the greater the hill-holding torque.

4. The pure electric vehicle hill-holding method according to claim 1, wherein in the torque variation gradient determination step, the larger the motor negative rotation speed n and the larger the motor output torque, the larger the corresponding δ Trq value.

5. The pure electric vehicle hill-holding method according to claim 2, characterized in that in the hill-holding torque locking step, hill-holding torque Trq _ F is set in a segmented manner according to the current rotation speed n and the rotation speed variation δ n, and the setting of Trq _ F is obtained according to empirical estimation and actual vehicle calibration.

6. The pure electric vehicle slope parking method according to claim 1, wherein in the rotating speed ring step, in the rotating speed ring zero-rotating-speed operation process, if the rotating speed of the motor has a forward rush or backward slip phenomenon, namely the absolute value | n | ≧ n1 of the rotating speed n, the rotating speed ring output torque is directly adjusted; if | n | < n1, still operating at the rotating speed PI ring;

7. The pure electric vehicle slope parking method according to claim 1, wherein the pure electric vehicle comprises a Vehicle Control Unit (VCU) and a Motor Controller (MCU); in the step of exiting the hill-holding mode, if a torque command Trq _ cmd sent by the VCU of the vehicle controller to the MCU is greater than a comparison value, exiting the hill-holding mode;

8. The pure electric vehicle slope parking method according to claim 1, wherein the pure electric vehicle comprises a Vehicle Control Unit (VCU) and a Motor Controller (MCU); and in the step of judging the slope state, judging whether the vehicle is in a slope slipping state or not through the motor controller MCU.

9. A pure electric vehicle hill-holding method is characterized by comprising a hill-holding state judging step, a hill-holding torque initializing step and a torque change gradient determining step;

wherein, Trq _1 is a torque set value and is related to vehicle parameters;

k is an empirical coefficient adjusted through actual calibration;