CN110194064A - Bi-motor integration pure electric vehicle passenger car power allocation strategy optimization method - Google Patents
Bi-motor integration pure electric vehicle passenger car power allocation strategy optimization method Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
- B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2220/00—Electrical machine types; Structures or applications thereof
- B60L2220/10—Electrical machine types
- B60L2220/14—Synchronous machines
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2220/00—Electrical machine types; Structures or applications thereof
- B60L2220/40—Electrical machine applications
- B60L2220/42—Electrical machine applications with use of more than one motor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/40—Drive Train control parameters
- B60L2240/42—Drive Train control parameters related to electric machines
- B60L2240/421—Speed
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/40—Drive Train control parameters
- B60L2240/42—Drive Train control parameters related to electric machines
- B60L2240/423—Torque
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/40—Drive Train control parameters
- B60L2240/54—Drive Train control parameters related to batteries
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
- B60W2050/0001—Details of the control system
- B60W2050/0019—Control system elements or transfer functions
- B60W2050/0028—Mathematical models, e.g. for simulation
- B60W2050/0037—Mathematical models of vehicle sub-units
- B60W2050/0039—Mathematical models of vehicle sub-units of the propulsion unit
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/72—Electric energy management in electromobility
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Abstract
The present invention relates to a kind of bi-motor integration pure electric vehicle passenger car power allocation strategy optimization methods, belong to power distribution field.By the relevant parameter for reasonably selecting bi-motor integration pure electric automobile, power allocation strategy (including Dynamic Programming strategy and the minimum strategy of instantaneous energy consumption) and rule-based power allocation strategy (Torque-sharing strategies such as bi-motor and major-minor motor torque allocation strategy) the relevant operating condition emulation of totally 4 kinds of strategy progress based on optimization method are applied respectively, the optimal policy of pure electric vehicle passenger car power distribution is found out in comparison, i.e. instantaneous optimization should be used as the best approach that the pure motor automobile power mode of integrated bi-motor is distributed.
Description
Technical field
The invention belongs to power to distribute field, be related to bi-motor integration pure electric vehicle passenger car power allocation strategy optimization side
Method.
Background technique
Swift and violent industrialization tide since along with 20th century, the mankind are faced with increasingly severeer energy crisis environment
Crisis and ecocrisis, people had a profound understanding of green energy conservation low-carbon the mode of production and life be sustainable development need
It wants.
Greatly developing electric car is exactly the important means for alleviating and coping with above-mentioned crisis, it has also become auto industry circle is total to
Know in bus field, pure electric automobile gains great popularity because of zero-emission low noise and the advantages that do not depend on fossil fuel with skill
The progress of art, pure electric automobile is more and more diversified on drive form, it is existing centralization driving, also have based on wheel motor,
Hub motor distributed drive form, and centralization driving can be divided into single motor and double electricity according to number of motors and configuration
These configurations of the types such as machine not only enrich the dynamic structure of pure electric automobile, also provide more to the optimization of its dynamic mode
Selection
Research object herein is a bi-motor integration pure electric automobile for being applied to city bus field, should
Dynamical system by two different outside output powers of motor form integration assembly of power compared with traditional single motor form,
Speed changer is not used on the more road in ramp；And the dynamical system improves drive while increasing drive system power
Dynamic reliability, when a certain motor break down when, another motor can also continue to work in addition, with two motors simply connect and
At dual motors system compare, the axial dimension of integrated dual motors system is more compact, can save arrangement space and reduce and is
The above-mentioned advantage of system quality bi-motor integrated dynamic system makes it receive the highest attention in market.
To the energy conversion system for containing two power sources, to realize the smallest energy consumption, need to carry out the optimization distribution of power
Common power allocation strategy has the rule-based strategy of rule-based and based on optimum theory control strategy i.e. according to preparatory
The distribution of the mode progress power or energy of setting includes Dynamic Programming (dynamic based on the control strategy of optimum theory
Programming, DP) it is equivalent it is energy consumption minimized strategy and the strategy based on Pang Te lia king minimal principle
Dynamic Programming is most widely used global optimization method in electric automobile energy or power assignment problem, it has also become
The standard of other strategies is measured, but it requires the information for providing driving cycle in advance in addition, Dynamic Programming has the calculating time long
Precision depends on the deficiencies of density degree and interpolation method of state variable grid dividing place and instantaneous energy consumption is minimum tactful
(instantaneous consumption minimum strategy, ICMS) can overcome Dynamic Programming to be difficult to apply in real time
The shortcomings that, but its shortcoming be inferior to global optimization in terms of energy consumption therefore, it is necessary to two kinds of strategies of DP and ICMS into
Row relatively and the pros and cons both weighed simultaneously, the relationship of the power allocation strategy based on global optimization and instantaneous optimization between the two
Be also required to further analyze in addition, for integrated dual-motor pure electric automobile, the power allocation strategy based on optimization method with
The torques such as bi-motor distribute (symmetric torque distribution, STD) major-minor motor and distribute (main-
Auxiliary distribution MAD) etc. it is rule-based strategy between energy consumption difference be also required to compare.
Based on above-mentioned consideration, the power assignment problem expansion in the present invention for bi-motor integration pure electric automobile is ground
Study carefully, respectively using the power allocation strategy of the Torque-sharing strategies master-auxiliary power allocation strategy based on Dynamic Programming such as bi-motor and
Based on the smallest power allocation strategy of instantaneous energy consumption, totally 4 kinds of strategies carry out the energy consumption analysis of vehicle, and carry out pair to 4 kinds of strategies
Than to obtain a kind of optimal power distribution scheme.
Summary of the invention
In view of this, the purpose of the present invention is to provide a kind of bi-motor integration pure electric vehicle passenger car power allocation strategies
Optimization method, to promote the dynamic property and cruising ability of pure electric automobile.
In order to achieve the above objectives, the invention provides the following technical scheme:
Bi-motor integration pure electric vehicle passenger car power allocation strategy optimization method, method includes the following steps:
S1: building bi-motor integration pure electric automobile model；
S2: the torque powers allocation strategy such as analysis bi-motor；
S3: the analysis major-minor power allocation strategy of bi-motor；
S4: the power allocation strategy of global optimization is analyzed；
S5: the power allocation strategy of instantaneous optimization is analyzed；
S6: power allocation strategy comparative analysis.
Further, in the S1, to complete vehicle structure and parameter, motor model, battery model and Full Vehicle Dynamics model
Assumed；
Two driving motors of motor model are permanent magnet synchronous motor, and big electric efficiency is expressed as the letter of torque and revolving speed
Number:
η1=μ1(T1,n1)
In formula: η1For big electric efficiency；T1And n1The output torque and revolving speed of respectively big motor；
Small machine efficiency is expressed as the function of torque and revolving speed:
η2=μ2(T2,n2)
In formula: η2For the efficiency of small machine；T2And n2The respectively output torque and revolving speed of small machine；
Battery is regarded as by open-circuit voltage UocWith equivalent internal resistance RbThe circuit being composed in series, and the two is expressed as the function of SOC:
Consider the battery system power balance equation of internal resistance power consumption are as follows:
Pbat=Pb+P1
In formula: PbatFor the total power consumption of battery；PbFor load end power consumption；P1For inside battery energy consumption；
According to the power-balance relationship in vehicle driving process in Full Vehicle Dynamics model, following equation is obtained:
In formula: P1' and P2' be respectively size electrical consumption electrical power；P1And P2The output work of respectively big small machine
Rate；PrFor drive/braking requirement power；PauxFor the electrical power consumed comprising the attachmentes such as steering motor and brake compressor；M is vehicle
Quality；G is acceleration of gravity；F is coefficient of rolling resistance；CdFor coefficient of air resistance；A is front face area；V is speed；δ is
Correction coefficient of rotating mass；T is the mechanical efficiency of transmission system；The revolving speed n of big small machine1And n2It is full under different working modes
Foot:
Further, in the S2, torque powers allocation strategy is waited to refer to full-vehicle control unit to two motor hairs of size
Identical torque command out, it may be assumed that
T1=T2=Tc
T in formulacFor the command torque of entire car controller；
The revolving speed having the same because of two motor coaxles, therefore drive/braking requirement power PrAre as follows:
And there are following relationships:
Then have:
Further, in the S3, the major-minor power allocation strategy of motor are as follows: torque and main motor can export according to demand
Torque capacity is judged；If demand torque is greater than main motor torque capacity, main motor is exported with torque capacity, and residue needs
Torque is asked to be provided by stand-by motor；Conversely, the main motor output specific formula of demand torque is expressed as follows:
And have:
In formula: TmaxlFor main motor torque capacity；For main motor external characteristics function；N is motor output shaft revolving speed；TrFor
Motor output shaft demand torque.
Further, in the S4, the energy consuming process of bi-motor all-in-one car is regarded as a dynamical system, then
System dynamics equation indicates are as follows:
X=f (x, u)
In formula: x is state variable；U is input variable；F is state equation；
It selects the SOC of battery for state variable, then state equation is obtained by battery model are as follows:
SOC=f (SOC)
By battery current
?
Select the output power of big motor for the input variable of system, it may be assumed that
U=P1
In addition, the instantaneous power consumption of vehicle indicates are as follows:
I.e. instantaneous power consumption is concluded are as follows:
Δ t is time step in formula, and value is 1s in calculating；
Based on the Bellman principle of optimization, objective function is minimised as with the electric energy consumed in entire stroke, is established discrete
The Dynamic Programming expression formula of form:
Work as k=kmaxWhen
As k≤kmaxWhen -1
In formula: i, h and k are respectively index amount；P1,iFor i-th of output power of big motor；SOChIt is discrete for h-th of SOC
Value；JkAdd up power consumption values to arrive the minimum of termination phase under kth stage and h-th of SOC discrete value.
Further, in the S5, instantaneous optimization is equivalent to currently walk with the minimum objective function of the power consumption currently walked
Power it is minimum, i.e., the optimal power selection of big small machine are as follows:
In formula: T1,iAnd P1,iThe torque that may be exported for big motor and corresponding power；T2,iAnd P2,iIt may for small machine
The torque of output and corresponding power；I and J is respectively the set of index series i and j while the power satisfaction for being apparent from big small machine
Following condition:
Pr,k=P1,i+P2,j
P in formular,kDriving or braking requirement power for kth step.
Further, in the S6, comprehensively consider 4 kinds of power allocation strategies in S2~S5, the power consumption under certain circulation
The SOC value to end with stroke.
The beneficial effects of the present invention are: global optimization is consistent with instantaneous optimization result, it the reason of are as follows: the bi-motor one
Body pure electric automobile has single energy source, i.e. ferric phosphate lithium cell (rather than includes the hybrid power system of battery and fuel
System)；The energy distribution of each step-length will not distribute the power consumption generated to the power in future and impact in entire driving cycle, be
The power Decision of Allocation of mutual independent event, i.e. kth step does not interfere with kth+1, the decision of k+2 ... ..., kmax step to
Global optimization is set to have identical with instantaneous optimization as a result, it is instantaneous optimization that i.e. global optimization, which is degenerated,.
From the perspective of use, DP algorithm requires to provide operating condition in advance, and instantaneous optimization is then not necessarily to predict work information,
Therefore with good real-time, instantaneous optimization should be used as the pure optimal power distribution method of motor automobile of bi-motor integration.
Pure electric automobile is distributed for bi-motor integrated dynamic, with the minimum objective function of power consumption in driving process,
The torques such as application distribute 4 kinds of power allocation strategies of major-minor distribution Dynamic Programming and instantaneous optimization and carry out continuous Chinese city respectively
The operating condition of car operation cycle emulates, and obtained conclusion is as follows:
(1) for bi-motor integration pure electric coach, the global optimization strategy based on Dynamic Programming is instantaneous by degenerating
Optimisation strategy is not necessarily based on the optimization that Dynamic Programming carries out power distribution, the optimum allocation of power can be realized in instantaneous optimization,
It should be used as optimal power allocation model；
(2) etc. Torque-sharing strategies have maximum power consumption, and major-minor allocation strategy takes second place.
Other advantages, target and feature of the invention will be illustrated in the following description to a certain extent, and
And to a certain extent, based on will be apparent to those skilled in the art to investigating hereafter, Huo Zheke
To be instructed from the practice of the present invention.Target of the invention and other advantages can be realized by following specification and
It obtains.
Detailed description of the invention
To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention is made below in conjunction with attached drawing excellent
The detailed description of choosing, in which:
Fig. 1 is that bi-motor integration pure electric vehicle power distributes overview flow chart；
Fig. 2 bi-motor integration pure electric vehicle power system structure；
The big electric efficiency performance plot of Fig. 3；
Fig. 4 small machine efficiency characteristic figure；
Fig. 5 battery cell open-circuit voltage and internal resistance with SOC variation；
The Typical Cities in China Fig. 6 car operation cycle；
Fig. 7 battery SOC curve；
The torque output of two motors of Fig. 8；
The big motor operating point distribution of Fig. 9；
The distribution of Figure 10 small machine operating point；
Figure 11 battery SOC curve；
The output power of two motors of Figure 12；
The big motor operating point distribution of Figure 13；
The distribution of Figure 14 small machine operating point；
Figure 15 battery SOC curve；
The output torque of two motors of Figure 16；
The big motor operating point distribution of Figure 17；
The distribution of Figure 18 small machine operating point；
Figure 19 battery SOC curve；
The output torque of two motors of Figure 20；
The big motor operating point distribution of Figure 21；
The distribution of Figure 22 small machine operating point.
Specific embodiment
Illustrate embodiments of the present invention below by way of specific specific example, those skilled in the art can be by this specification
Other advantages and efficacy of the present invention can be easily understood for disclosed content.The present invention can also pass through in addition different specific realities
The mode of applying is embodied or practiced, the various details in this specification can also based on different viewpoints and application, without departing from
Various modifications or alterations are carried out under spirit of the invention.It should be noted that diagram provided in following embodiment is only to show
Meaning mode illustrates basic conception of the invention, and in the absence of conflict, the feature in following embodiment and embodiment can phase
Mutually combination.
Wherein, the drawings are for illustrative purposes only and are merely schematic diagrams, rather than pictorial diagram, should not be understood as to this
The limitation of invention；Embodiment in order to better illustrate the present invention, the certain components of attached drawing have omission, zoom in or out, not
Represent the size of actual product；It will be understood by those skilled in the art that certain known features and its explanation may be omitted and be in attached drawing
It is understood that.
The same or similar label correspond to the same or similar components in the attached drawing of the embodiment of the present invention；It is retouched in of the invention
In stating, it is to be understood that if there is the orientation or positional relationship of the instructions such as term " on ", "lower", "left", "right", "front", "rear"
To be based on the orientation or positional relationship shown in the drawings, be merely for convenience of description of the present invention and simplification of the description, rather than indicate or
It implies that signified device or element must have a particular orientation, be constructed and operated in a specific orientation, therefore is described in attached drawing
The term of positional relationship only for illustration, is not considered as limiting the invention, for the ordinary skill of this field
For personnel, the concrete meaning of above-mentioned term can be understood as the case may be.
Fig. 1 is that bi-motor integration pure electric vehicle power distributes overview flow chart.The pure electric automobile that the present invention studies
For a city bus, power system architecture is as shown in Figure 2.The power source of vehicle is two different motors of watt level,
And the rotor coaxial of two motors is connected on same output shaft, motor output shaft is directly driven by flange and transmission axis connection
Vehicle driving.
Whole-car parameters are as shown in table 1.
1 whole-car parameters table of table
Two driving motors of motor model be permanent magnet synchronous motor wherein, big motor (No. 1 motor) maximum speed is
3000r/min, torque capacity be 2100N m, maximum power 150kW, efficiency characteristic as shown in figure 3, i.e. be expressed as torque and
The function of revolving speed:
Small machine (No. 2 motors) maximum speed be 3000r/min, torque capacity be 850N m, maximum power 135kW,
Efficiency as shown in figure 4, is equally expressed as the function of torque and revolving speed by its efficiency characteristic.
In addition, during vehicle braking, it is contemplated that the protection to battery and motor sets the maximum generation of two motors
Power is 40kW.
In battery model power battery type be ferric phosphate lithium cell, by 160 it is monomer series-connected in groups, nominal capacity is
360Ah, total voltage are that 512V battery external characteristics is based on Rint model and obtains, i.e., regard battery by open-circuit voltage Uoc and equivalent as
The circuit that internal resistance Rb is composed in series, and the two is expressed as the function of SOC.Based on experimental data, single battery open-circuit voltage is obtained
With equivalent internal resistance with the variation characteristic of SOC, as shown in Figure 5.
Operating condition emulation is carried out, under the torque powers allocation strategy such as bi-motor with 20 continuous Typical Cities in China cars
The simulation analysis of equal torque powers allocation strategy is carried out for operation cycle CCBC (see Fig. 6).The continuous duty mileage is total
117.8km, duration 7.3h, concurrently setting battery SOC initial value is 0.9.
Fig. 7 is the change curve of battery SOC, and SOC is down to 0.21 at the end of stroke, and the total power consumption of vehicle is 121.72kWh,
For clarity, Fig. 8 gives two motors and recycles (1~1314s) in first CCBC every 1km average consumption 1.03kWh
When output torque；It is found that the torque that big small machine output phase is same, and its value is within the working range of motor.
The distribution of two motor operating points is as shown in Figure 9 and Figure 10；It is found that under equal Torque-sharing strategies, due to big small machine
Output power it is little, so that most of operating point is distributed in the lower region of efficiency.
Operating condition emulation is carried out under the major-minor power allocation strategy of bi-motor, major-minor power allocation strategy is based on, with same
Operating condition is emulated (SOC initial value is 0.9,20 continuous CCBC circulations)
By the SOC curve of Figure 11 it is found that SOC is down to 0.23 at the end of stroke, add up power consumption 118.48kWh, through converting,
Its 100km power consumption reduces 3.23kW h compared with equal torque strategies.
Figure 12 is the time history of the output power of big small machine, it is known that, the power output of big motor plays a major role, small
Motor only work it is quantitative when vehicle demand power is bigger analysis shows, small machine only works in driving condition, and
Duration only accounts for the 0.76% of whole driving process.
By the motor operating point distribution of Figure 13 and Figure 14 as it can be seen that big motor will become main under major-minor power allocation strategy
Power source, compared with equal Torque-sharing strategies, big motor operating point distributed areas are extended to high efficient area under major-minor strategy, small
It reduces by a relatively large margin the corresponding operating point of motor.
The operating condition of power allocation strategy based on global optimization emulates, and is based on DP algorithm, at the beginning of 20 CCBC circulations and SOC
Value carries out simulation analysis for 0.9 operating condition, and it is 200 points that state variable is discrete in numerical value calculating, and discrete input variable is 100
Point, i.e. i=100, h=200 and k=1314 × 20 estimate that the interpolation method of accumulative energy consumption is linear interpolation
The battery SOC end value obtained based on DP strategy is 0.25, and as shown in figure 15, every 1km average current drain is 0.98kW h,
It is significantly less than equal torque strategies and major-minor power allocation strategy equally for clarity,
Figure 16 gives the output torque of first CCBC circulation (1~1314s) two motor
Figure 17 and Figure 18 is respectively the operating point distribution of two motors, it can be seen that following features
(1) small machine operates mainly in high speed area, and big motor operates mainly in low rotation speed area；Big motor when driving
High efficient district is operated mainly in, small machine works in the higher point of efficiency under corresponding revolving speed
(2) when demand power is little and speed is higher, only small machine provides driving force；When demand power is little and vehicle
When speed is lower, only big motor provides driving force；When demand power is larger, big motor is mentioned with larger torque output, small machine
Drive that there is a situation where larger in vehicle start uniform acceleration demand simultaneously for two motor of part assist torque
(3) quantitative analysis is recycled in braking process it is found that small machine consumes electric energy 50.06kW h during driving
Electric energy 11.50kW h；Big motor consumes electric energy 66.86kWh during driving, recycles electric energy 22.786kW h in braking process
The operating condition of power allocation strategy based on instantaneous optimization emulates: being still 0.9,20 continuous with the initial SOC of battery
CCBC circulation carries out the emulation based on instantaneous energy consumption optimal policy.
Figure 19 be SOC variation track for clarity.
Figure 20 gives local motor torque output.
Figure 21 and Figure 22 is the operating point distribution carefully comparison discovery of two motors, is based on the resulting SOC rail of instantaneous optimization
The results such as mark and the distribution of motor operating point with it is completely the same based on DP acquired results, i.e., it is instantaneous that global optimization based on DP, which is degenerated,
Optimization.
Power allocation strategy comparative analysis
Table 2 is that power consumption and stroke of 4 kinds of power allocation strategies when 20 CCBC are recycled and SOC initial value is 0.9 are ended
SOC value, which can be seen that equal Torque-sharing strategies, has maximum power consumption, and major-minor allocation strategy takes second place, and the overall situation/instantaneous optimization has
The smallest power consumption, and its 100km journey power consumption is respectively than waiting torques distribution and major-minor allocation model few by 3.31 and 6.02kW h
2 different dynamic allocation strategy result of table compares
The global optimization reason consistent with instantaneous optimization result are as follows: the bi-motor integration pure electric automobile has single
Energy source, i.e. ferric phosphate lithium cell (rather than including the hybrid power system of battery and fuel)；Each step in entire driving cycle
Long energy distribution will not distribute the power consumption generated to the power in future and impact, and be independent of each other event, i.e. kth walks
Power Decision of Allocation does not interfere with kth+1, the decision of k+2 ... ..., kmax step, so that global optimization be made to have and instantaneous excellent
Change identical as a result, it is instantaneous optimization that i.e. global optimization, which is degenerated,
From the perspective of use, DP algorithm requires to provide operating condition in advance, and instantaneous optimization is then not necessarily to predict work information,
Therefore with good real-time, instantaneous optimization should be used as the pure optimal power distribution method of motor automobile of bi-motor integration
Pure electric automobile is distributed for bi-motor integrated dynamic, with the minimum objective function of power consumption in driving process,
The torques such as application distribute 4 kinds of power allocation strategies of major-minor distribution Dynamic Programming and instantaneous optimization and carry out continuous Chinese city respectively
The operating condition of car operation cycle emulates, and obtained conclusion is as follows:
(1) for bi-motor integration pure electric coach, the global optimization strategy based on Dynamic Programming is instantaneous by degenerating
Optimisation strategy is not necessarily based on the optimization that Dynamic Programming carries out power distribution, the optimum allocation of power can be realized in instantaneous optimization,
It should be used as optimal power allocation model；
(2) etc. Torque-sharing strategies have maximum power consumption, and major-minor allocation strategy takes second place, based on Dynamic Programming/instantaneous excellent
Changing has the smallest power consumption, and 100km power consumption is fewer by 5.07 than equal torques allocation model and major-minor allocation model respectively and 2.29kW
h。
Finally, it is stated that the above examples are only used to illustrate the technical scheme of the present invention and are not limiting, although referring to compared with
Good embodiment describes the invention in detail, those skilled in the art should understand that, it can be to skill of the invention
Art scheme is modified or replaced equivalently, and without departing from the objective and range of the technical program, should all be covered in the present invention
Scope of the claims in.
Claims (7)
1. bi-motor integration pure electric vehicle passenger car power allocation strategy optimization method, it is characterised in that: this method includes following
Step:
S1: building bi-motor integration pure electric automobile model；
S2: the torque powers allocation strategy such as analysis bi-motor；
S3: the analysis major-minor power allocation strategy of bi-motor；
S4: the power allocation strategy of global optimization is analyzed；
S5: the power allocation strategy of instantaneous optimization is analyzed；
S6: power allocation strategy comparative analysis.
2. bi-motor integration pure electric vehicle passenger car power allocation strategy optimization method as described in claim 1, feature exist
In: in the S1, complete vehicle structure and parameter, motor model, battery model and Full Vehicle Dynamics model are assumed；
Two driving motors of motor model are permanent magnet synchronous motor, and big electric efficiency is expressed as the function of torque and revolving speed:
η1=μ1(T1,n1)
In formula: η1For big electric efficiency；T1And n1The output torque and revolving speed of respectively big motor；
Small machine efficiency is expressed as the function of torque and revolving speed:
η2=μ2(T2,n2)
In formula: η2For the efficiency of small machine；T2And n2The respectively output torque and revolving speed of small machine；
Battery is regarded as by open-circuit voltage UocWith equivalent internal resistance RbThe circuit being composed in series, and the two is expressed as the function of SOC:
Consider the battery system power balance equation of internal resistance power consumption are as follows:
Pbat=Pb+P1
In formula: PbatFor the total power consumption of battery；PbFor load end power consumption；P1For inside battery energy consumption；
According to the power-balance relationship in vehicle driving process in Full Vehicle Dynamics model, following equation is obtained:
In formula: P1' and P2' be respectively size electrical consumption electrical power；P1And P2The output power of respectively big small machine；PrFor
Drive/braking requirement power；PauxFor the electrical power consumed comprising the attachmentes such as steering motor and brake compressor；M is vehicle mass；g
For acceleration of gravity；F is coefficient of rolling resistance；CdFor coefficient of air resistance；A is front face area；V is speed；δ is gyrating mass
Conversion coefficient；T is the mechanical efficiency of transmission system；The revolving speed n of big small machine1And n2Meet under different working modes:
3. bi-motor integration pure electric vehicle passenger car power allocation strategy optimization method as described in claim 1, feature exist
In: in the S2, torque powers allocation strategy is waited to refer to that full-vehicle control unit issues identical torque to two motors of size
Order, it may be assumed that
T1=T2=Tc
T in formulacFor the command torque of entire car controller；
The revolving speed having the same because of two motor coaxles, therefore drive/braking requirement power PrAre as follows:
And there are following relationships:
Then have:
4. bi-motor integration pure electric vehicle passenger car power allocation strategy optimization method as described in claim 1, feature exist
In: in the S3, the major-minor power allocation strategy of motor are as follows: the torque capacity that torque and main motor can export according to demand carries out
Judgement；If demand torque is greater than main motor torque capacity, main motor is exported with torque capacity, and unmet demand torque is by assisting
Motor provides；Conversely, the main motor output specific formula of demand torque is expressed as follows:
And have:
In formula: TmaxlFor main motor torque capacity；fT1For main motor external characteristics function；N is motor output shaft revolving speed；TrFor motor
Output shaft demand torque.
5. bi-motor integration pure electric vehicle passenger car power allocation strategy optimization method as described in claim 1, feature exist
In: in the S4, regard the energy consuming process of bi-motor all-in-one car as a dynamical system, then system dynamics side
Journey indicates are as follows:
X=f (x, u)
In formula: x is state variable；U is input variable；F is state equation；
It selects the SOC of battery for state variable, then state equation is obtained by battery model are as follows:
SOC=f (SOC)
By battery current
?
Select the output power of big motor for the input variable of system, it may be assumed that
U=P1
In addition, the instantaneous power consumption of vehicle indicates are as follows:
I.e. instantaneous power consumption is concluded are as follows:
Δ t is time step in formula, and value is 1s in calculating；
Based on the Bellman principle of optimization, objective function is minimised as with the electric energy consumed in entire stroke, establishes discrete form
Dynamic Programming expression formula:
Work as k=kmaxWhen
As k≤kmaxWhen -1
In formula: i, h and k are respectively index amount；P1,iFor i-th of output power of big motor；SOChFor h-th of SOC discrete value；Jk
Add up power consumption values to arrive the minimum of termination phase under kth stage and h-th of SOC discrete value.
6. bi-motor integration pure electric vehicle passenger car power allocation strategy optimization method as described in claim 1, feature exist
In: in the S5, instantaneous optimization is equivalent to the power currently walked minimum with the minimum objective function of the power consumption currently walked,
The optimal power of i.e. big small machine selects are as follows:
In formula: T1,iAnd P1,iThe torque that may be exported for big motor and corresponding power；T2,iAnd P2,iIt may be exported for small machine
Torque and corresponding power；I and J is respectively that the power satisfaction of index series i and j gathered while being apparent from big small machine is as follows
Condition:
Pr,k=P1,i+P2,j
P in formular,kDriving or braking requirement power for kth step.
7. bi-motor integration pure electric vehicle passenger car power allocation strategy optimization method as described in claim 1, feature exist
In: in the S6, comprehensively consider 4 kinds of power allocation strategies in S2~S5, power consumption and stroke are ended under certain circulation
SOC value.
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