CN108073554B - Power-assisted characteristic curve design method of automobile electric power-assisted steering system based on SOC - Google Patents

Power-assisted characteristic curve design method of automobile electric power-assisted steering system based on SOC Download PDF

Info

Publication number
CN108073554B
CN108073554B CN201810010869.2A CN201810010869A CN108073554B CN 108073554 B CN108073554 B CN 108073554B CN 201810010869 A CN201810010869 A CN 201810010869A CN 108073554 B CN108073554 B CN 108073554B
Authority
CN
China
Prior art keywords
soc
curve
power
battery
assisted
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201810010869.2A
Other languages
Chinese (zh)
Other versions
CN108073554A (en
Inventor
武健
徐广飞
吴海荣
王锋波
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Liaocheng University
Original Assignee
Liaocheng University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Liaocheng University filed Critical Liaocheng University
Priority to CN201810010869.2A priority Critical patent/CN108073554B/en
Publication of CN108073554A publication Critical patent/CN108073554A/en
Application granted granted Critical
Publication of CN108073554B publication Critical patent/CN108073554B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/18—Complex mathematical operations for evaluating statistical data, e.g. average values, frequency distributions, probability functions, regression analysis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/17—Function evaluation by approximation methods, e.g. inter- or extrapolation, smoothing, least mean square method

Abstract

The invention discloses a power-assisted characteristic curve design method of an automobile electric power-assisted steering system based on SOC, which comprises the steps of estimating the SOC of a battery, carrying out classification smoothing processing according to the value of the SOC of the battery, carrying out change processing on a comparative example zeta in the process of calculating a target current by using a hand moment, and processing a curve at the full speed. The estimation of the SOC of the battery comprehensively utilizes methods such as a current integration method, an open-circuit voltage method, a battery internal resistance method and the like, and the estimation precision of the SOC is effectively ensured; and carrying out classification smoothing processing according to the SOC value of the battery, and respectively smoothing the original curve type boosting characteristic curves by considering the conditions that the SOC is less than 40% and the SOC is more than 40%. In the process of designing the power-assisted curve, on one hand, the smoothing treatment is carried out on the basis of the curve-type power-assisted curve, so that the effect is better; on the other hand, the patent enables the design based on the consideration of the battery power to ensure the continuous supply of the battery current.

Description

Power-assisted characteristic curve design method of automobile electric power-assisted steering system based on SOC
Technical Field
The invention relates to an EPS (electric power steering) power-assisted characteristic curve, in particular to a method for designing an SOC (system on chip) -based power-assisted characteristic curve of an automobile electric power steering system.
Background
The power characteristic curve of the EPS is a relationship between a power current of a motor and parameters such as a steering wheel input torque, a vehicle running speed, a front wheel air pressure, a front axle weight and the like, and the control requirement can be satisfied by considering two main parameters of the steering wheel input torque and the vehicle running speed in general.
The power-assisted characteristic curve of the EPS is a key technology of an EPS software system. The boost characteristic curve determines the magnitude of the boost current to be controlled by a controller (ECU) according to what target to meet the requirements on the boost torque under different driving conditions. The basic power characteristic curve is roughly divided into: linear, broken line, curved.
The basic power assisting characteristic curve can basically meet the design requirement, but the actual effect of the power assisting is poor, so that the improved design of the power assisting characteristic curve appears, wherein the curve type power assisting characteristic curve design with adjustable parameters is adopted, the shape of the curve type power assisting characteristic curve is changed through the set parameters, and the curve can be changed at any time. The double-slope smooth power-assisted curve has a double-slope smooth power-assisted curve, can independently calibrate curve parameters according to different hand feeling requirements of a small power-assisted area and a large power-assisted area, has the advantages of smooth power assistance, independent parameter function and easiness in debugging, and can better meet the expectation of a driver in the aspect of steering hand feeling.
The above design only starts from the curve itself, does not consider the influence of battery power on the vehicle power assistance, and when the hand moment change is great and the hand moment is great, the battery is very likely to be unable to provide the EPS current that satisfies the requirement, and the EPS system can cut off the power supply suddenly, and the steering power assistance system can not function in the twinkling of an eye, seriously influences driving safety.
Chinese patent application No. 200810202069.7, which discloses an "electric power steering system with independently adjustable parameter curve type power assist characteristic"; the existing parameter adjustment enables the design period of the curve to be long, and meanwhile, the actual condition of the vehicle cannot be contacted, so that the curve adjustment is carried out according to the actual condition of the vehicle.
Chinese patent application No. 201010600546.2 discloses an electric power steering system having a dual-slope smooth assist curve, which cannot ensure the practical application effect of the assist curve, i.e., whether the continuous supply of the battery power can be ensured or not, in the process of performing dual-slope smoothing processing in a polygonal line segment.
Disclosure of Invention
The invention aims to solve the technical problem of providing a power-assisted characteristic curve design method of an automobile electric power-assisted steering system based on SOC, which considers the influence of battery electric quantity on vehicle power assistance, can provide EPS current meeting requirements when the hand moment is changed greatly and the hand moment is large, and can not be powered off suddenly, thereby ensuring the normal function of the power-assisted steering system and ensuring the driving safety.
In order to solve the technical problems, the invention adopts the following technical means:
a design method of an assistance characteristic curve of an automobile electric power steering system based on SOC is disclosed, the design of the assistance characteristic curve considers the condition of the SOC of a battery, smoothing processing is carried out on the basis of an original curve type assistance characteristic curve in the curve design process, meanwhile, current required by an EPS system is restrained to ensure that the battery can have stable and continuous current output even under the condition of low electric quantity, and the realization of the whole assistance process of the EPS is ensured, wherein the curve design comprises the following steps:
step 1) estimating the SOC of the battery;
step 2) carrying out smoothing treatment on the SOC (state of charge) of less than 40% by a weighted moving average method corresponding to the curve-shaped power-assisted characteristic curve, and improving the change rate of the curve-shaped power-assisted curve so as to stabilize the current output of the battery;
step 3) carrying out simple moving average smoothing processing on the curve type power-assisted characteristic curve under the condition that the SOC is more than 40%;
step 4) in the process of calculating the target current by using the hand moment:
Ia＝ξTd (1)
wherein, TdIs hand moment, IaIs the target current, xi is a proportional relation coefficient, the proportional relation xi is changed,
Figure GDA0002743947380000021
lambda is a transformation coefficient, and a power-assisted curve under the required vehicle speed is determined;
and 5) for different vehicle speeds in different stages, obtaining complete power-assisted characteristic curves under different vehicle speeds through related terms of the speed, namely:
I＝e-av·ξTd (2)
where I is the target current for each vehicle speed, e-avThe correction factor is a factor that includes velocity.
Compared with the prior art, the invention adopting the technical scheme has the outstanding characteristics that:
when the power-assisted characteristic curve is designed, the SOC condition is considered, particularly under the conditions of large hand moment change and large hand moment, the change rate of the power-assisted curve is changed, and the current of the EPS is controlled to be within the battery power supply range. The SOC value can be observed by comprehensively utilizing a current integration method, an open-circuit voltage method, a battery internal resistance method and the like, the original curve type power-assisted characteristic curve is subjected to condition division processing according to the SOC value, the original curve type power-assisted characteristic curve is subjected to smoothing processing by a weighted moving average method when the SOC is less than 40%, and the original curve type power-assisted characteristic curve is subjected to smoothing processing by a simple moving average method when the SOC is more than 40%. And meanwhile, the required current of the EPS is restrained, and the continuous supply of the battery to the EPS current is ensured, so that the power-assisted steering system continuously plays a role.
The residual capacity of the battery is considered in curve design, meanwhile, on the basis of an original curve type power-assisted characteristic curve, calculation of target current can be better achieved under the condition of meeting practical application, and stable output of actual tracking current is guaranteed. In the process of designing the power-assisted curve, on one hand, the smoothing treatment is carried out on the basis of the curve-type power-assisted curve, so that the effect is better; on the other hand, the design of this patent is carried out on the basis of considering battery electric quantity, can guarantee the continuous supply of battery current, simultaneously, in the calculation process of carrying out the target current, has carried out certain optimization restriction to the target current that produces because of hand moment, can further guarantee the stability of the electric current of battery.
The further preferred technical scheme is as follows:
the method for designing the power-assisted characteristic curve of the automobile electric power-assisted steering system based on the SOC comprises the following steps that 1) the SOC of a battery is estimated, namely the SOC of the battery is estimated by comprehensively utilizing a current integration method, an open-circuit voltage method and a battery internal resistance method; the actual capacity of the battery is integrated by current ampere-hour corrected in the complete charging process of the battery, and SOC estimation in the using process is divided into two parts, namely a discharging process SOC and a charging process SOC; during discharging, according to the current state of charge, in the curve of the internal resistance of the batteryReading charging internal resistance RCCalculating the current voltage V of the battery core according to the charging currentOC(ii) a From the charging relationship, one can obtain:
VOC＝VC-RC×IC (3)
in the formula, VOCIs the voltage of the battery core, VCTo discharge voltage, RCIs the internal resistance of the battery, ICDischarging current for the battery; calculating VOCSOC-V with correctionOCThe curve can be used to obtain the estimated value of open-circuit SOC, and the estimated value is recorded as SOCOC(ii) a The SOC value calculated by the ampere-hour integration method at this time is as follows:
Figure GDA0002743947380000031
in the formula, QNCharge number, i (t) is current per unit time, t is time, dt represents integration over time; according to SOCOCAnd SOCATComprehensively estimating the battery load state by adopting the following equation:
SOCC＝η1×SOCOC＝η2×SOCAT (5)
in the formula eta1And η2For correcting the coefficient, according to the characteristics of the lithium ion battery, the battery has a capacity interval of 10% -90%, the voltage change is small, the voltage value is still close to the rated voltage value of the power supply after the voltage value is changed, the correction coefficient can be flexibly set according to the characteristics of different batteries, the battery capacity interval of 10% -90% is set, the ampere-hour integral is set to be dominant, eta is set1Is 0.2,. eta2Is 0.8; capacity of battery<10% and>at 90%, the open-circuit voltage estimation dominates, and η is set1Is 0.8, η2Is 0.2; eta3And η4To correct the coefficient, SOCCFor the total estimation of the SOC during charging, SOCDFor an overall estimation of the SOC during discharge, SOCOCAccording to SOC-VOCSOC value, SOC, calculated from the curveATThe SOC value is calculated according to an ampere-hour integration method; the discharge process is based onCalculating the open load state SOC according to the dataOCLoad state SOC calculated by ampere-hour integrationATThe corrected battery load state is as follows:
SOCD＝η3×SOCOC+η4×SOCAT (6)
in the method for designing the power-assisted characteristic curve of the SOC-based automobile electric power-assisted steering system, the function of the curve-shaped power-assisted characteristic curve in the step 2) is as follows:
Figure GDA0002743947380000041
wherein the content of the first and second substances,
Figure GDA0002743947380000042
Td0to initiate a minimum hand moment, T, for assistancemaxFor assisting to terminate maximum hand moment, MmaxAt the maximum moment of assistance, a1，b1，b2，B3Is a constant coefficient; f (v) is a power assisting curve system corresponding to different speeds, F (v) is a function of the vehicle speed v, the faster v is, the smaller F (v) is, an exponential decreasing function of v is taken, G (T)d) For the boost curves at different steering wheel torque inputs, the boost function is increased, i.e. the higher the steering wheel input torque, the higher the boost torque must be for ease of steering.
In the method for designing the power-assisted characteristic curve of the SOC-based automobile electric power-assisted steering system, step 2) smooth processing is performed by a weighted moving average method corresponding to the curve-shaped power-assisted characteristic curve, and the calculation formula of the weighted moving average method is as follows:
Ft＝w1A1+w2A2+w3A3+…+wnAn (8)
in the formula, FtTo predict the next point, A1，A2，……AnTaking n actual values, w, of the original power characteristic curve1-the weight of the 1 st point actual value; w is a2- - (2) pointA weight of the actual value; w is an-the weight of the actual value at the nth point; n- -number of predicted values; w is a1+w2+…+wn＝1。
The moving average method is a simple smooth prediction technology, and the basic idea is as follows: and calculating the time-sequence average value containing a certain number of terms in sequence according to the time-sequence data item by item in order to reflect the long-term trend. Therefore, when the time series numerical value is influenced by the periodic variation and the random fluctuation, the fluctuation is large, and the development trend is not easy to be displayed, the influence of the factors can be eliminated by using the moving average method, the development direction and the trend (namely, the trend line) of the event can be displayed, and then the long-term trend of the time series can be analyzed and predicted according to the trend line.
The design method of the power-assisted characteristic curve of the automobile electric power-assisted steering system based on the SOC comprises the following steps of 3) carrying out simple moving average smoothing treatment on a curve type power-assisted characteristic curve when the SOC is more than 40%; the weights of the elements of the simple moving average are all equal, and the calculation formula of the simple moving average is as follows:
Ft＝(A1+A2+A3+…+An)/n (9)
in the formula, FtIn, t represents a corner mark, Ft-a predicted value for the next point; n-number of moving average points; a. the1-an actual value of a previous point; a. the2，A3And AnRespectively representing the actual values of the first two points, the first three points and the point from the first n point.
Drawings
Figure 1 is a curved boost characteristic curve of the prior art.
Fig. 2 is a power assist characteristic curve for the case where the SOC of the present invention is < 40%.
FIG. 3 is a power assist characteristic curve for a SOC > 40% of the present invention.
FIG. 4 is a flow chart of an SOC based boost characteristic curve design of the present invention.
Detailed Description
The present invention will be further described with reference to the following examples.
Referring to fig. 1, the basic curve type boosting characteristic curve of the prior art can basically meet the design requirement, but the actual effect of boosting is poor, especially when the hand torque is rapidly increased. In view of the above, there has been proposed an improved design of a power assist characteristic curve, in which a curve type power assist characteristic curve having adjustable parameters is designed, and the curve can be changed at any time by changing the shape of the curve type power assist characteristic curve by using set parameters. The double-slope smooth power-assisted curve has a double-slope smooth power-assisted curve, can independently calibrate curve parameters according to different hand feeling requirements of a small power-assisted area and a large power-assisted area, has the advantages of smooth power assistance, independent parameter function and easiness in debugging, and can better meet the expectation of a driver in the aspect of steering hand feeling. The above design only starts from the curve itself, does not consider the influence of battery power on the vehicle power assistance, and when the hand moment change is great and the hand moment is great, the battery is very likely to be unable to provide the EPS current that satisfies the requirement, and the EPS system can cut off the power supply suddenly, and the steering power assistance system can not function in the twinkling of an eye, seriously influences driving safety.
Referring to fig. 2, 3 and 4, in the method for designing the power-assisted characteristic curve of the electric power-assisted steering system of the vehicle based on the SOC of the invention, the power-assisted characteristic curve is designed in consideration of the SOC of the battery, smoothing is performed on the basis of the original curve-type power-assisted characteristic curve in the curve design process, and the current required by the EPS system is restricted to ensure that the battery can output a stable and continuous current even under the condition of low electric quantity, so as to ensure the realization of the whole power-assisted process of the EPS, wherein the curve design comprises the following steps:
step 1) estimating the SOC of the battery;
step 2) carrying out smoothing treatment on the SOC (state of charge) of less than 40% by a weighted moving average method corresponding to the curve-shaped power-assisted characteristic curve, and improving the change rate of the curve-shaped power-assisted curve so as to stabilize the current output of the battery;
step 3) carrying out simple moving average smoothing processing on the curve type power-assisted characteristic curve under the condition that the SOC is more than 40%;
step 4) in the process of calculating the target current by using the hand moment:
Ia＝ξTd (10)
wherein, TdIs hand moment, IaThe target current is shown as xi, the proportional relation coefficient is shown as xi, the proportional relation xi is changed,
Figure GDA0002743947380000061
lambda is a transformation coefficient, and a power-assisted curve under the required vehicle speed is determined; when the hand torque measured by the torque sensor is converted into the target current, the power characteristic curve can be smoothed by changing the conversion coefficient, so that the target current value is always kept in the discharge current range of the battery, namely
Figure GDA0002743947380000062
The curve can be made to have a laterally elongated effect.
Step 5) passing the correlation term e related to the speed under different vehicle speeds in different stages-avObtaining complete power-assisted characteristic curves under different vehicle speeds, namely:
I＝e-av·ξTd (11)
where I is the target current for each vehicle speed, e-avThe correction factor is a factor that includes velocity.
The method comprises the steps that 1) the SOC of a battery is estimated, namely the SOC of the battery is estimated by comprehensively utilizing a current integration method, an open-circuit voltage method and a battery internal resistance method; the actual capacity of the battery is integrated by current ampere-hour corrected in the complete charging process of the battery, and SOC estimation in the using process is divided into two parts, namely a discharging process SOC and a charging process SOC; during the discharging process, reading the charging internal resistance R in the battery internal resistance curve according to the current charge stateCCalculating the current voltage V of the battery core according to the charging currentOC(ii) a From the charging relationship, one can obtain:
VOC＝VC-RC×IC (12)
calculating VOCCarry-in correctionSOC-V ofOCThe curve can be used to obtain the estimated value of open-circuit SOC, and the estimated value is recorded as SOCOC(ii) a The SOC value calculated by the ampere-hour integration method at this time is as follows:
Figure GDA0002743947380000063
wherein Q isNCharge number, i (t) is current per unit time, t is time, dt represents integration over time; according to SOCOCAnd SOCATComprehensively estimating the battery load state by adopting the following equation:
SOCC＝η1×SOCOC+η2×SOCAT (14)
in the formula eta1And η2For correcting the coefficient, according to the characteristics of the lithium ion battery, the battery has a capacity interval of 10% -90%, the voltage change is small, the voltage value is still close to the rated voltage value of the power supply after the voltage value is changed, the correction coefficient can be flexibly set according to the characteristics of different batteries, the battery capacity interval of 10% -90% is set, the ampere-hour integral is set to be dominant, eta is set1Is 0.2,. eta2Is 0.8; capacity of battery<10% and>at 90%, the open-circuit voltage estimation dominates, and η is set1Is 0.8, η2Is 0.2; eta3And η4To correct the coefficient, SOCCFor the total estimation of the SOC during charging, SOCDFor an overall estimation of the SOC during discharge, SOCOCAccording to SOC-VOCSOC value, SOC, calculated from the curveATThe SOC value is calculated according to an ampere-hour integration method;
the discharge process calculates the state SOC of the open-circuit load according to the dataOCLoad state SOC calculated by ampere-hour integrationATThe corrected battery load state is as follows:
SOCD＝η3×SOCOC+η4×SOCAT (15)
the method for designing the power-assisted characteristic curve of the automobile electric power-assisted steering system based on the SOC comprises the following steps of 2) enabling a function of a curve-shaped power-assisted characteristic curve to be:
Figure GDA0002743947380000071
wherein the content of the first and second substances,
Figure GDA0002743947380000072
Td0to initiate a minimum hand moment, T, for assistancemaxFor assisting to terminate maximum hand moment, MmaxAt the maximum moment of assistance, a1，b1，b2，B3Is a constant coefficient, F (v) is a power assisting curve system corresponding to different speeds, F (v) is a function of a vehicle speed v, the faster v is, the smaller F (v) is, an exponential decreasing function of v is taken, G (T)d) For the boost curves at different steering wheel torque inputs, the boost function is increased, i.e. the higher the steering wheel input torque, the higher the boost torque must be for ease of steering.
An assistance characteristic curve design method of an automobile electric power steering system based on SOC (system on chip), comprising the following steps of 2) carrying out smoothing treatment on a curve assistance characteristic curve corresponding to the condition that the SOC is less than 40%, wherein a calculation formula of a weighted moving average method is as follows:
Ft＝w1A1+w2A2+w3A3+…+wnAn (17)
in the formula, FtTo predict the next point, A1，A2，……AnTaking n actual values, w, of the original power characteristic curve1-the weight of the 1 st point actual value; w is a2-the weight of the actual value at point 2; w is an-the weight of the actual value at the nth point;
n- -number of predicted values; w is a1+w2+…+w n1. Selecting n points At-1，At-2，At-3… …, a series of points (x) are obtained1，y1)，(x2，y2)，(x3，y3) … … taking the initial value as T1The points are taken according toAnd (4) secondary substitution: ft＝w1A1+w2A2+w3A3+…+wnAn(ii) a To obtain In＝w1T1+w2T2+w3T3+…+wnTn。
The design method of the power-assisted characteristic curve of the automobile electric power-assisted steering system based on the SOC comprises the following steps of 3) carrying out simple moving average smoothing treatment on a curve type power-assisted characteristic curve under the condition that the SOC is more than 40%; the weights of the elements of the simple moving average are all equal, and the calculation formula of the simple moving average is as follows:
Ft＝(A1+A2+A3+…+An)/n (18)
in the formula, Ft-a predicted value for the next point; n-number of moving average points; a. the1-the actual value of the previous point; a. the2，A3And AnRespectively representing the actual values of the first two points, the first three points and the point from the first n point.
Taking n points A1，A2，A3… …, a series of points (x) are obtained1，y1)，(x2，y2)(x3，y3) … … taking the initial value as T1And substituting the taken points in sequence: ft＝(A1+A2+A3+…An) N; to obtain In＝(T1+T2+T3+…Tn)/n。
As can be seen from fig. 4, this embodiment performs estimation of the battery SOC, classification smoothing processing according to the value of the battery SOC, change processing on the proportional relation ξ in the process of calculating the target current by using the hand moment, and processing on the curve at the full vehicle speed. The estimation of the SOC of the battery comprehensively utilizes methods such as a current integration method, an open-circuit voltage method, a battery internal resistance method and the like, and the estimation precision of the SOC is effectively ensured; and carrying out classification smoothing processing according to the SOC value of the battery, and respectively smoothing the original curve type boosting characteristic curves by considering the conditions that the SOC is less than 40% and the SOC is more than 40%.
As can be seen from a comparison of fig. 1, 2, and 3, when designing the assist characteristic curve, the current of the EPS is controlled within the battery power supply range by changing the change rate of the assist curve in consideration of the SOC, particularly, when the hand torque changes greatly and is large. The SOC value can be observed by comprehensively utilizing a current integration method, an open-circuit voltage method, a battery internal resistance method and the like, the original curve type power-assisted characteristic curve is subjected to condition division processing according to the SOC value, the original curve type power-assisted characteristic curve is subjected to smoothing processing by a weighted moving average method when the SOC is less than 40%, and the original curve type power-assisted characteristic curve is subjected to smoothing processing by a simple moving average method when the SOC is more than 40%. And meanwhile, the required current of the EPS is restrained, and the continuous supply of the battery to the EPS current is ensured, so that the power-assisted steering system continuously plays a role.
The beneficial effect of this embodiment lies in: the residual capacity of the battery is considered during curve design, and meanwhile, the curve design is based on the original curve type power-assisted characteristic curve, calculation of the target current can be better achieved under the condition of meeting practical application, and stable output of the actual tracking current is guaranteed. In the process of designing the power-assisted curve, on one hand, the smoothing treatment is carried out on the basis of the curve-type power-assisted curve, so that the effect is better; on the other hand, the design of this patent on the basis of considering battery electric quantity can guarantee the continuous supply of battery current, simultaneously, in the calculation process of carrying out the target current, has carried out certain optimization restriction to the target current that produces because of hand moment, can further guarantee the stability of the electric current of battery.
Since the above description is only a specific embodiment of the present invention, but the protection of the present invention is not limited thereto, any equivalent changes or substitutions of the technical features of the present invention which can be conceived by those skilled in the art are included in the protection scope of the present invention.

Claims (4)

1. A method for designing a power-assisted characteristic curve of an automobile electric power-assisted steering system based on SOC is characterized by comprising the following steps: the design of the power-assisted characteristic curve considers the condition of the SOC of the battery, the smoothing processing is carried out on the basis of the original curve type power-assisted characteristic curve in the curve design process, the current required by the EPS system is restrained to ensure that the battery can have stable and continuous current output even under the condition of low electric quantity, the realization of the whole power-assisted process of the EPS is ensured, and the curve design comprises the following steps:
step 1) estimating the SOC of the battery; the SOC of the battery is estimated by comprehensively utilizing a current integration method, an open-circuit voltage method and a battery internal resistance method to estimate the state of charge of the battery;
step 2) for the SOC of less than 40%, carrying out smoothing treatment on the curve-shaped power-assisted characteristic curve by a weighted moving average method, and improving the change rate of the curve-shaped power-assisted curve so as to stabilize the current output of the battery; the function of the curve-shaped power-assisted characteristic curve is:
Figure FDA0002935258280000011
wherein the content of the first and second substances,
Figure FDA0002935258280000012
f (v) is a power assisting curve system corresponding to different speeds, F (v) is a function of the vehicle speed v, the faster v is, the smaller F (v) is, an exponential decreasing function of v is taken, G (T)d) For the power-assisted curves when different steering wheel torques are input, the power-assisted torque is an increasing function, namely the larger the input torque of the steering wheel is, and the larger the power-assisted torque is required to be for light steering;
step 3) carrying out simple moving average smoothing processing on the curve type power-assisted characteristic curve of the formula (1) under the condition that the SOC is more than 40%;
step 4) in the process of calculating the target current by using the hand moment:
Ia＝ζTd (2)
wherein the comparative example relation ζ is subjected to a changing treatment,
Figure FDA0002935258280000013
lambda is a transformation coefficient, and a power-assisted curve under a certain vehicle speed is determined;
and 5) for different vehicle speeds in different stages, obtaining complete power-assisted characteristic curves under different vehicle speeds through related terms of the speed, namely:
I＝e-av·ζTd； (3)
where I is the target current for each vehicle speed, e-avThe correction factor is a factor that includes velocity.
2. The method of designing a power assist characteristic curve of an electric power steering system for an automobile based on SOC according to claim 1, characterized in that: the SOC of the battery is estimated in the step 1), the actual capacity of the battery adopts current ampere-hour integral after the correction of the complete charging process of the battery, and the SOC estimation in the using process is divided into two parts, one is the SOC in the discharging process and the other is the SOC in the charging process; during the discharging process, reading the charging internal resistance RC in the battery internal resistance curve according to the current charge state, and calculating the current battery inner core voltage V according to the charging currentOC(ii) a From the charging relationship, one can obtain:
VOC＝VC-RC×IC (4)
calculating VOCSOC-V with correctionOCObtaining the estimated value of open circuit SOC by curve and recording the estimated value as SOCOC(ii) a The SOC value calculated by the ampere-hour integration method at this time is as follows:
Figure FDA0002935258280000021
according to SOCOCAnd SOCATComprehensively estimating the battery load state by adopting the following equation:
SOCC＝η1×SOCOC+η2×SOCAT (6)
in the formula eta1And η2For correcting the coefficient, the battery has small voltage change in the 10-90% capacity interval according to the characteristics of the lithium ion battery, the correction coefficient is flexibly set according to the characteristics of different batteries, the correction coefficient is set in the 10-90% capacity interval of the battery, and the safety coefficient is setTime integral predominance, η1Is 0.2,. eta2Is 0.8; capacity of battery<10% and>at 90%, the open-circuit voltage estimation dominates, and η is set1Is 0.8, η2Is 0.2;
the discharge process calculates the state SOC of the open-circuit load according to the dataOCLoad state SOC calculated by ampere-hour integrationATThe corrected battery load state is as follows:
SOCD＝η3×SOCOC+η4×SOCAT (7)。
3. the method of designing a power assist characteristic curve of an electric power steering system for an automobile based on SOC according to claim 1, characterized in that: step 2) carrying out smoothing treatment on the curve-shaped power assisting characteristic curve by a weighted moving average method, wherein the calculation formula of the weighted moving average method is as follows:
Ft＝w1A1+w2A2+w3A3+…+wnAn (8)
in the formula, w1-the weight of the 1 st point actual value; w is a2-the weight of the actual value at point 2; w is an-the weight of the actual value at the nth point; n- -number of predicted values; w is a1+w2+…+wn＝1。
4. The method of designing a power assist characteristic curve of an electric power steering system for an automobile based on SOC according to claim 1, characterized in that: the step 3) carries out simple moving average smoothing processing on the curve type power-assisted characteristic curve when the SOC is more than 40%; the weights of the elements of the simple moving average are all equal, and the calculation formula of the simple moving average is as follows:
Ft＝(A1+A2+A3+…+An)/n (9)
in the formula, Ft-a predicted value for the next point; n-number of moving average points; a. the1-the actual value of the previous point; a. the2，A3And AnRespectively showing the front two points and the front three pointsUp to the actual value of the first n points.
CN201810010869.2A 2018-01-05 2018-01-05 Power-assisted characteristic curve design method of automobile electric power-assisted steering system based on SOC Active CN108073554B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201810010869.2A CN108073554B (en) 2018-01-05 2018-01-05 Power-assisted characteristic curve design method of automobile electric power-assisted steering system based on SOC

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201810010869.2A CN108073554B (en) 2018-01-05 2018-01-05 Power-assisted characteristic curve design method of automobile electric power-assisted steering system based on SOC

Publications (2)

Publication Number Publication Date
CN108073554A CN108073554A (en) 2018-05-25
CN108073554B true CN108073554B (en) 2021-04-02

Family

ID=62156336

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201810010869.2A Active CN108073554B (en) 2018-01-05 2018-01-05 Power-assisted characteristic curve design method of automobile electric power-assisted steering system based on SOC

Country Status (1)

Country Link
CN (1) CN108073554B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111017005A (en) * 2018-10-10 2020-04-17 森源汽车股份有限公司 Torque control method and system for electric power-assisted transport vehicle
CN110908383B (en) * 2019-12-03 2021-05-28 安徽江淮汽车集团股份有限公司 Method and apparatus for adjusting electric power steering system, and storage medium

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101624050A (en) * 2009-08-03 2010-01-13 奇瑞汽车股份有限公司 Hybrid-power battery SOC self-adaptive control method
CN102530055A (en) * 2010-12-22 2012-07-04 上海联盛汽车电子有限公司 Electric power steering system with double-gradient smooth assist curves
JP2015042510A (en) * 2013-08-26 2015-03-05 三菱自動車工業株式会社 Electric power source device for hybrid vehicle
CN105480297A (en) * 2014-10-06 2016-04-13 三菱自动车工业株式会社 Electric steering device
CN107117202A (en) * 2017-04-10 2017-09-01 大连创新零部件制造公司 Automobile electric booster steering system with intelligent overload protection function

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101624050A (en) * 2009-08-03 2010-01-13 奇瑞汽车股份有限公司 Hybrid-power battery SOC self-adaptive control method
CN102530055A (en) * 2010-12-22 2012-07-04 上海联盛汽车电子有限公司 Electric power steering system with double-gradient smooth assist curves
JP2015042510A (en) * 2013-08-26 2015-03-05 三菱自動車工業株式会社 Electric power source device for hybrid vehicle
CN105480297A (en) * 2014-10-06 2016-04-13 三菱自动车工业株式会社 Electric steering device
CN107117202A (en) * 2017-04-10 2017-09-01 大连创新零部件制造公司 Automobile electric booster steering system with intelligent overload protection function

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
基于GＲNN 网络车辆方向盘转角识别方法;武健 等;《应用基础与工程科学学报》;20140228;全文 *
电动助力转向系统助力特性曲线的分析与改进;余为清 等;《拖拉机与农用运输车》;20110630;全文 *

Also Published As

Publication number Publication date
CN108073554A (en) 2018-05-25

Similar Documents

Publication Publication Date Title
US9120531B2 (en) Motor driving control apparatus
JP6619836B2 (en) Motor drive control device
CN107187446A (en) The cruise control method and device of electric vehicle
CN108073554B (en) Power-assisted characteristic curve design method of automobile electric power-assisted steering system based on SOC
CN103270693A (en) Motor drive control device
CN103448863A (en) Motor drive control device
CN103770832A (en) Assisted power controlling method for electric power assisted steering system
JP4488067B2 (en) Boost converter circuit for vehicle
CN108197392A (en) The assist characteristic curve design method of automobile electric booster steering system based on SOC
JP2017081319A (en) Control device for hybrid vehicle
US20200307388A1 (en) System and method for compensating acceleration of electrical motorbike
JP2001224108A (en) Motor control device for electric vehicle
JP6939399B2 (en) Boost converter device
JP4980457B2 (en) Electronic throttle valve control device
JP2007057234A (en) Internal resistance estimator for secondary battery
JP4434647B2 (en) Control device and bicycle
CN113135094B (en) Battery recharging strength control method for electric vehicle
TW202123575A (en) Battery regenerative strength control method for electronic vehicle
JP4831038B2 (en) Motor torque control device
JP6544483B2 (en) Power supply
CN114056479A (en) Self-adaptive electric power-assisted bicycle torque control method and control system
JP5328971B1 (en) Regenerative braking system for internal combustion engine
CN117239891A (en) Energy recovery method and device for electric two-wheeled vehicle
JP2008168770A (en) Behavior control device for vehicle

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant