CN106114287A - A kind of electric automobile antiskid control system and control method - Google Patents

Abstract

The present invention provides a kind of electric automobile antiskid control system, including control unit for vehicle, PID controller, driving motor, TA_maxMemorizer and TA value detection module, control unit for vehicle and PID controller and driving motor are connected, and TA value detection module is connected with driving motor and PID controller, TA_maxMemorizer is connected with PID controller, and control unit for vehicle is used for encouraging driving motor, and TA value detection module drives the TA value signal of motor output for detecting, and PID controller compares TA_maxValue and TA value also send a command to control unit for vehicle so that TA value is consistently less than TA_maxValue, TA_maxMemorizer is used for storing TA_maxValue, TA value is equal to driving wheel angular acceleration and the ratio of Motor torque.Electric automobile antiskid control system disclosed by the invention, use parameter TA to replace traditional slip rate, it is to avoid the measurement to vehicle velocity signal, equipment without vehicle speed measurement, simultaneously without the auxiliary of dependence conventional hydraulic brakes, reduce production cost, improve system stability.

Description

A kind of electric automobile antiskid control system and control method

Technical field

The present invention relates to electric automobile field, particularly relate to a kind of based on wheel angular acceleration with the electricity of Motor torque ratio Electrical automobile antiskid control system and control method.

Background technology

From controlling for angle, motor topmost advantage compared with internal combustion engine is that it can not only be used for driving means and also may be used As performing device.Make it can have diversified vehicle as the feature of driving means, small size and high-power output to drive Dynamic allocation plan.As performing device, quick response characteristic and moment information feedback, it is achieved that the most accurate and effective dynamic Mechanics controls in real time.So that electric vehicle is not only environmental protection, controls technology by advanced motorized and can realize tool There are higher active safety, control stability and the driving experience of more preferable riding comfort.

Vehicle safe anti-slipping control in, in traditional internal-combustion engines vehicle use anti-lock braking system (ABS) and TCS (TCS) realizes the function being correlated with.It generally uses double-parameter controlling method to assess vehicle row Wheelslip situation in sailing.Two-parameter control methods needs to measure and obtains car speed and the information of this necessity of wheel velocity, Then it is used for calculating slip rate.Slip rate is one of parameter of expression wheel locking or the slipping state being widely used, double In parameters control method, need to prevent wheel from skidding by restriction slip rate.Traditional anti-skid controller uses slip rate Represent locking or the slipping state of wheel.When the vehicle accelerates, it is assumed that ω r > v, slip rate is defined as:

$\mathrm{\λ}=\frac{\mathrm{\ω}r-v}{\mathrm{\ω}r}---\left(1\right)$

Wherein v is the longitudinal velocity of vehicle, and ω is the angular velocity of wheel, and r is wheel equivalent redius.When the vehicle is decelerating, Due to ω r < v, the expression formula of slip rate can be written as:

$\mathrm{\&lambda;}=\frac{v-\mathrm{\&omega;}r}{v}---\left(2\right)$

Relation between slip rate and the coefficient of friction on road surface is complex, and surface friction coefficient is one and rubs for representing The scalar of the ratio between wiping power and vertical normal pressure, it is defined as follows:

$\mathrm{\&mu;}=\frac{F_f}{F_n}---\left(3\right)$

Wherein F_fIt is frictional force, and F_nIt it is vertical normal pressure.

As it is shown in figure 1, (slip rate that maximum is corresponding is generally situated between before surface friction coefficient reaches near its maximum Between 0.1 and 0.3), surface friction coefficient is the increasing function of slip rate, and this section of region is referred to as the range of linearity, in linear zone In territory, the running status of wheel is stablized controlled, thus is also a stability region.After this region, along with slip rate Becoming much larger, not only surface friction coefficient starts to diminish, simultaneously also into a unstable region.In unstable region, car The running status unstability of wheel, it may occur however that serious skidding.Therefore, slip rate is typically to be limited by the anti-skid controller of vehicle System is in corresponding safety zone.

Traditional two-parameter control methods limiting slip rate has been widely used in the anti-lock system of current industrial quarters In the controller of dynamic system and TCS.But on the one hand the method relies on hydraulic brake mechanism execution and holds OK, brake cost requirement is increased；On the other hand the method needs necessary sensing equipment, completes the essence of Vehicle Speed etc. Really measuring, such as accelerometer, optical pickocff, GPS etc., these equipment all can cause the increase of cost；The increase of its equipment is also Make to be susceptible to fault or Signal Fail under given conditions, as being difficult to obtain gps signal etc. in tunnel.For electricity Machine drives electric vehicle, can utilize the quick response advantage of motor body completely, play it simultaneously as executor and sensing The feature of device designs corresponding antiskid control system.

Being different from traditional double parameter anti-sliding control, the present invention takes full advantage of Motor torque and can quickly and accurately obtain The unique advantage of this electric automobile, devises new parameter TA, is used for replacing traditional slip rate method, carries out the anti-of vehicle Slip control system.In new parameter TA, the accekeration the two parameter of the torque value and wheel of having used motor calculates, And both is all easily obtainable on electric automobile, it is not necessary to additional sensors；Simultaneously without brake fluid system Cooperation, directly utilize motor body as actuator.Therefore, the present invention be a kind of cost lower be applicable to electric automobile Efficient anti-skid control method.

Summary of the invention

The technical problem to be solved is to use new parameter TA, replaces traditional slip rate method, for understanding Certainly the problems referred to above, the present invention provides a kind of electric automobile antiskid control system, including control unit for vehicle, PID controller, driving Motor, TA_maxMemorizer and TA value detection module, control unit for vehicle and PID controller and driving motor are connected, and TA value detects Module is connected with driving motor and PID controller, TA_maxMemorizer is connected with PID controller, and control unit for vehicle is used for encouraging Driving motor, TA value detection module drives the TA value signal of motor output for detecting, and PID controller compares TA_maxValue and TA value And send a command to control unit for vehicle so that TA value is consistently less than TA_maxValue, TA_maxMemorizer is used for storing TA_maxValue, TA Value is equal to driving wheel angular acceleration and the ratio of Motor torque.

Further, PID controller includes PI controller.

Further, antiskid control system also includes a low pass filter, and low pass filter is for removing at driving wheel The high-frequency noise that angular acceleration produces in calculating.

Invention additionally discloses the control method of a kind of electric automobile antiskid control system, comprise the steps:

Step one: the detection of TA value detection module drives the TA value in motor operation course, and transmits to PID controller；

Step 2: PID controller compares TA value and TA_maxValue, when TA value is more than TA_maxDuring value, reduction is turned round by PID controller The instruction of square is transmitted to control unit for vehicle；

Step 3: the moment of torsion needing output is applied to drive motor by control unit for vehicle, and driving wheel angular acceleration reduces, Thus realize TA value less than TA_maxValue.

Further, in step 2, TA value is calculated by equation below (4):

$TA=\frac{\stackrel{\&CenterDot;}{\mathrm{\&omega;}}}{T}---\left(4\right)$

Wherein T is Motor torque；ω is driving wheel angular velocity,It it is driving wheel angular acceleration.

Further, TA_maxIt is calculated by equation below (7):

$TA=\frac{1}{\mathrm{\&alpha;}\&CenterDot;{\mathrm{Mr}}^2+J}---\left(7\right)$

Wherein, α is that vehicle travels acceleration and the ratio with wheel equivalent line acceleration, and M is vehicle mass, and J is wheel Rotary inertia, r is radius of wheel.

There is advantages that

1, a kind of based on wheel angular acceleration and Motor torque ratio the electric automobile anti-skid control method of the present invention, makes Replace traditional slip rate by parameter TA, it is not necessary to the equipment accurately measured of car load travel speed, reduce production cost, improve System stability.

2, in a kind of based on wheel angular acceleration and Motor torque ratio the electric automobile antiskid control system of the present invention By utilizing motor body as executor, the regulation being driven moment real-time, it is not necessary to the liquid of conventional anti skid system Pressure brake coordinates, and reduces equipment further and relies on.

3, in a kind of based on wheel angular acceleration and Motor torque ratio the electric automobile anti-skid control method of the present invention The TA single parameter used controls, and takes full advantage of Motor torque and can quickly and accurately obtain this unique advantage, algorithm letter Bright it is easily achieved.

Accompanying drawing explanation

Fig. 1 is the relation schematic diagram between coefficient of friction and slip rate.

Fig. 2 is that electric automobile takes turns kinetics schematic diagram.

Fig. 3 is a kind of based on wheel angular acceleration and Motor torque ratio the electric automobile antiskid control system of the present invention Structural representation.

Fig. 4 is that in antiskid control system, one-parameter TA and vehicle travel acceleration and the ratio pair of wheel equivalent line acceleration Answer graph of a relation.

Detailed description of the invention

Below in conjunction with the accompanying drawings and with reference to data, the present invention is described in further detail.Should be understood that embodiment is intended merely to lift The example explanation present invention, rather than limit the scope of invention by any way.

As it is shown on figure 3, a kind of electric automobile antiskid control system of the present invention and method, including control unit for vehicle, PID Controller, driving motor and TA value detection module, control unit for vehicle and PID controller and driving motor are connected, and TA value detects Module is connected with driving motor and PID controller, and control unit for vehicle is used for encouraging driving motor, TA value detection module to be used for examining Surveying the TA value signal driving motor output, PID controller compares TA_maxValue and TA value and send a command to control unit for vehicle from And make TA value be consistently less than TA_maxValue, TA_maxMemorizer is used for storing TA_maxValue, TA value is equal to driving wheel angular acceleration and motor The ratio of moment of torsion.When vehicle driver's bend the throttle, send torque command to control unit for vehicle.PID controller is passed through One typical PID (PID) controls, and is applied to required output moment of torsion drive motor, and PID controller is used Carry out the monitoring parameter TA that limiting wheel skids, keep it stable within the safety zone of self, to prevent wheel from skidding； PID controller is PI controller in one embodiment.

In the present invention, the definition of TA is represented by formula (4):

$TA=\frac{\stackrel{\&CenterDot;}{\mathrm{\&omega;}}}{T}---\left(4\right)$

Wherein T is Motor torque；ω is driving wheel angular velocity,It it is driving wheel angular acceleration；

As in figure 2 it is shown, the kinetic expression during automobile tire travels is as follows:

$\begin{array}{c}J\stackrel{\&CenterDot;}{\mathrm{\&omega;}}=T-f\&CenterDot;r,\\ M\stackrel{\&CenterDot;}{v}=f,\end{array}---\left(5\right)$

Wherein M is vehicle mass, and v is Vehicle Speed, and f is surface resistance, and ω is driving wheel angular velocity, and J is tire Rotary inertia, T is Motor torque, and r is radius of wheel.

If definition α is vehicle travels acceleration and the ratio with wheel equivalent line acceleration, such as following formula:

$\mathrm{\&alpha;}=\frac{\stackrel{\&CenterDot;}{v}}{\stackrel{\&CenterDot;}{\mathrm{\&omega;}}r}---\left(6\right)$

Further, derive in conjunction with formula (4) (5) (6), TA can be derived and be calculated by equation below (7):

$TA=\frac{1}{\mathrm{\&alpha;}\&CenterDot;{\mathrm{Mr}}^2+J}---\left(7\right)$

Wherein TA_maxValue can obtain according to the span of α.

The invention also discloses a kind of electric automobile anti-sliding control side based on wheel angular acceleration and Motor torque ratio Method, comprises the steps:

Step one: the detection of TA value detection module drives the TA value in motor operation course, and transmits to PID controller；

Step 2: PID controller compares TA value and TA_maxValue, when TA value is more than TA_maxDuring value, reduction is turned round by PID controller The instruction of square is transmitted to control unit for vehicle；

Step 3: the moment of torsion needing output is applied to drive motor by control unit for vehicle, and driving wheel angular acceleration reduces, Thus realize TA value less than TA_maxValue.

In the embodiment shown in fig. 3, the TA value size during first step needs assessment draws vehicle traveling.Use and drive motor The Motor torque T of Real-time Feedback own and the driving wheel angular acceleration of driving motor transmissionBeing input to TA value detection module can To obtain corresponding assessed value in real time.Owing to Study on Vehicle Dynamic Control (including anti-sliding control) usually requires that at relatively low frequency In the range of rate, (100-1000 hertz) is carried out, it is possible to removes with a low pass filter and calculates at driving wheel angular acceleration In issuable high-frequency noise.

The second step needs assessment vehicle implemented maintains the TA value permissible range of safe sliding in travelling.At anti-skid controller Design process in, TA value can be limited in its safety zone, in figure 3 this limits value TA_maxRepresent.

Standard definition according to slip rate, it is Vehicle Speed v and the ratio calculation of tire linear velocity, one Individual expression formula such as following formula (8):

$\mathrm{\&lambda;}=1-\frac{v}{\mathrm{\&omega;}r}---\left(8\right)$

Definition α is that vehicle travels acceleration and the ratio of wheel equivalent line acceleration, such as following formula (9):

$\mathrm{\&alpha;}=\frac{\stackrel{\&CenterDot;}{v}}{\stackrel{\&CenterDot;}{\mathrm{\&omega;}}r}---\left(9\right)$

In conjunction with two formula above, slip rate λ can derive equation below (10):

$\mathrm{\&lambda;}=1-\frac{v}{\mathrm{\&omega;}r}=1-\frac{{\&Integral;}_0^t\stackrel{\&CenterDot;}{v}\left(t\right)dt}{{\&Integral;}_0^t\stackrel{\&CenterDot;}{\mathrm{\&omega;}}\left(t\right)rdt}=1-\frac{\mathrm{\&alpha;}{\&Integral;}_0^t\stackrel{\&CenterDot;}{\mathrm{\&omega;}}\left(t\right)dt}{{\&Integral;}_0^t\stackrel{\&CenterDot;}{\mathrm{\&omega;}}\left(t\right)dt}---\left(10\right)$

The control limit of α is relevant with slip rate λ, it is assumed that the value of α is bounded, and its upper limit is α_H, lower limit is α_L, then go up The scope of the slip rate λ in formula can be expressed by following formula:

$1-\frac{{\mathrm{\&alpha;}}_H{\&Integral;}_0^t\stackrel{\&CenterDot;}{\mathrm{\&omega;}}\left(t\right)dt}{{\&Integral;}_0^t\stackrel{\&CenterDot;}{\mathrm{\&omega;}}\left(t\right)dt}\&le;\mathrm{\&lambda;}\&le;1-\frac{{\mathrm{\&alpha;}}_L{\&Integral;}_0^t\stackrel{\&CenterDot;}{\mathrm{\&omega;}}\left(t\right)dt}{{\&Integral;}_0^t\stackrel{\&CenterDot;}{\mathrm{\&omega;}}\left(t\right)dt}---\left(11\right)$

According to vehicle travel in tire license slip rate experience range, be appreciated that slip rate λ typically 0.1-0.3 it Between can realize safety traffic.Safety range according to above formula and then the α that can derive is between 0.7 to 0.9.By formula (7), can obtain As follows to the maximum occurrences limit value of TA:

${\mathrm{TA}}_{\max }=\frac{1}{{\mathrm{\&alpha;}}_L\&CenterDot;{\mathrm{Mr}}^2+J}---\left(12\right)$

The 3rd step implemented, in figure 3, when the TA value of actual measurement is more than TA_maxTime, controller thinks that wheel there occurs skidding Phenomenon.Now, PID controller calculates the torque value needing output, and the torque value of these needs output makes TA value less than TA_max Value, realizes the reduction of driving wheel angular acceleration by the control instruction reducing moment of torsion.Those skilled in the art are readily apparent that, when When Motor torque T reduces, driving wheel angular accelerationAlso can reduce therewith, due to the driving wheel angular acceleration of slipping stateSubtract Little amplitude is bigger, thus controls TA value and reduce to realize less than TA_maxValue.During this controls, TA would be held in In the range of one rational, in order to ensure to drive wheel not enter slipping state.

The preferred embodiment of the present invention described in detail above.Should be appreciated that those of ordinary skill in the art without Need creative work just can make many modifications and variations according to the design of the present invention.Therefore, all technology in the art Personnel are available by logical analysis, reasoning, or a limited experiment the most on the basis of existing technology Technical scheme, all should be in the protection domain being defined in the patent claims.

Claims (6)

1. an electric automobile antiskid control system, it is characterised in that include control unit for vehicle, PID controller, driving electricity Machine, TA_maxMemorizer and TA value detection module, described control unit for vehicle and described PID controller and described driving motor phase Even, described TA value detection module is connected with described driving motor and described PID controller, described TA_maxMemorizer and described PID Controller is connected, and described control unit for vehicle is used for encouraging described in described driving motor, described TA value detection module be used for detecting Driving the TA value signal of motor output, described PID controller compares TA_maxValue and TA value also send a command to described wagon control Unit is so that described TA value is consistently less than described TA_maxValue, described TA_maxMemorizer is used for storing described TA_maxValue, described TA Value is equal to driving wheel angular acceleration and the ratio of Motor torque.

2. a kind of electric automobile antiskid control system as claimed in claim 1, it is characterised in that described PID controller includes PI controller.

3. a kind of electric automobile antiskid control system as claimed in claim 1, it is characterised in that described antiskid control system is also Including a low pass filter, described low pass filter is for removing the high frequency produced in described driving wheel angular acceleration calculates Noise.

4. the control method of an electric automobile antiskid control system, it is characterised in that comprise the steps:

Step one: the detection of TA value detection module drives the TA value in motor operation course, and transmits to PID controller；

Step 2: PID controller compares TA value and TA_maxValue, when TA value is more than TA_maxDuring value, PID controller will reduce moment of torsion Instruction transmission is to control unit for vehicle；

Step 3: the moment of torsion needing output is applied to drive motor by control unit for vehicle, and driving wheel angular acceleration reduces, thus Realize TA value less than TA_maxValue.

5. control method as claimed in claim 4, it is characterised in that in described step 2, TA value is counted by equation below (4) Obtain:

$TA=\frac{\stackrel{\&CenterDot;}{\mathrm{\&omega;}}}{T}---\left(4\right)$

Wherein T is Motor torque；ω is driving wheel angular velocity,It it is driving wheel angular acceleration.

6. control method as claimed in claim 4, it is characterised in that described TA_maxIt is calculated by equation below (7):

$TA=\frac{1}{\mathrm{\&alpha;}\&CenterDot;{\mathrm{Mr}}^2+J}---\left(7\right)$

Wherein, α is that vehicle travels acceleration and the ratio with wheel equivalent line acceleration, and M is vehicle mass, and J is vehicle wheel rotation Inertia, r is radius of wheel.