CN114407667A - Braking energy feedback efficiency determination method and device, electric vehicle and storage medium - Google Patents

Braking energy feedback efficiency determination method and device, electric vehicle and storage medium Download PDF

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CN114407667A
CN114407667A CN202210127494.4A CN202210127494A CN114407667A CN 114407667 A CN114407667 A CN 114407667A CN 202210127494 A CN202210127494 A CN 202210127494A CN 114407667 A CN114407667 A CN 114407667A
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electric automobile
vehicle
representing
power
braking
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张营
齐浩然
景智敏
周帅康
王健
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Northwestern Polytechnical University
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Northwestern Polytechnical University
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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
    • B60L7/00—Electrodynamic brake systems for vehicles in general
    • B60L7/10—Dynamic electric regenerative braking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/10—Vehicle control parameters
    • B60L2240/12—Speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/10—Vehicle control parameters
    • B60L2240/14—Acceleration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/10—Vehicle control parameters
    • B60L2240/26—Vehicle weight

Abstract

The invention discloses a method and a device for determining braking energy feedback efficiency, an electric vehicle and a storage medium, and relates to the technical field of vehicles. The method solves the problems of high testing difficulty, large calculated amount and low calculation precision of the conventional method for determining the braking energy feedback efficiency. The method comprises the following steps: at each sampling moment, acquiring the total mass, the speed, the acceleration, the voltage value and the current value of the electric automobile at the current moment; determining the total braking force and the braking power of the electric vehicle at the current moment according to the total mass, the speed and the acceleration of the electric vehicle at the current moment; determining the feedback power of the power battery of the electric automobile at the current moment according to the voltage value and the current value of the electric automobile at the current moment; and determining the braking energy feedback efficiency of the electric automobile at the current moment according to the vehicle braking power and the power battery feedback power of the electric automobile at the current moment.

Description

Braking energy feedback efficiency determination method and device, electric vehicle and storage medium
Technical Field
The invention relates to the technical field of automobiles, in particular to a method and a device for determining braking energy feedback efficiency, an electric automobile and a storage medium.
Background
The method and the device for controlling the braking energy feedback of the electric automobile are generally applied to the electric automobile, and play a key role in compensating the energy loss of the storage battery of the electric automobile so as to improve the economy of the whole automobile and further greatly improve the endurance mileage of the electric automobile. The energy conversion efficiency of the electric automobile in the braking process directly determines the amount of feedback energy, and has important significance for optimizing a regenerative braking control strategy in real time. However, the regenerative braking system of the electric vehicle is complex, energy conversion experience links are many, system parameters are many, and the regenerative braking system has time-varying characteristics, so that the real-time braking energy feedback efficiency cannot be directly measured by a sensor, and the regenerative braking system is difficult to accurately acquire by simple calculation.
Disclosure of Invention
The embodiment of the invention provides a method and a device for determining braking energy feedback efficiency, an electric vehicle and a storage medium, and solves the problems of high testing difficulty, large calculation amount and low calculation precision of the conventional method for determining the braking energy feedback efficiency.
The embodiment of the invention provides a method for determining braking energy feedback efficiency, which comprises the following steps:
at each sampling moment, acquiring the total mass, the speed, the acceleration, the voltage value and the current value of the electric automobile at the current moment;
determining the total braking force and the braking power of the electric vehicle at the current moment according to the total mass, the speed and the acceleration of the electric vehicle at the current moment;
determining the feedback power of the power battery of the electric automobile at the current moment according to the voltage value and the current value of the electric automobile at the current moment;
and determining the braking energy feedback efficiency of the electric automobile at the current moment according to the vehicle braking power and the power battery feedback power of the electric automobile at the current moment.
Preferably, the total braking force of the vehicle at the present time is determined by the following formula:
Figure BDA0003501073410000021
wherein, Fb(k) Representing the braking force of a vehicle at the kth moment, k representing the kth sampling moment, theta representing the slope angle of the road surface, mu representing the rolling friction coefficient, m representing the total mass of the electric automobile, g representing the gravity acceleration of the electric automobile, v representing the running speed of the electric automobile at the kth sampling moment, a representing the acceleration of the electric automobile at the kth sampling moment, rho representing the rolling friction factor between the electric automobile tire and the running road surface, A representing the direct contact area of the windward side in the running process of the electric automobile, CdIs the air resistance coefficient.
Preferably, the vehicle braking power is determined according to the following formula:
Pb(k)＝Fb(k)v(k)
wherein, Fb(k) V (k) represents the vehicle braking force at the k-th sampling time, v (k) represents the driving speed of the electric vehicle at the k-th sampling time, Pb(k) The vehicle braking power at the kth sampling instant is indicated.
Preferably, the feedback power of the power battery of the electric automobile is determined according to the following formula:
PB(k)＝Ui(k)Ii(k)
wherein, PB(k) Represents the feedback power of the power battery of the electric automobile at the kth sampling moment Ui(k) Represents the real-time voltage value, I, fed back by the vehicle power battery at the k-th sampling momenti(k) And the real-time current value fed back by the vehicle power battery at the kth sampling moment is represented.
Preferably, the braking energy feedback efficiency of the electric automobile at the current moment is determined according to the following formula:
Figure BDA0003501073410000022
wherein, PB(k) Represents the feedback power P of the power battery of the electric automobile at the k sampling momentb(k) Indicating the braking power of the vehicle at the k-th sampling momentRate, etabAnd representing the braking energy feedback efficiency of the electric automobile at the kth sampling moment.
The embodiment of the invention provides a braking energy feedback efficiency determining device, which comprises:
the acquisition unit is used for acquiring the total mass, the speed, the acceleration, the voltage value and the current value of the electric automobile at the current moment at each sampling moment;
the first determining unit is used for determining the total braking force and the braking power of the vehicle at the current moment according to the total mass, the vehicle speed and the acceleration of the electric vehicle at the current moment;
the second determining unit is used for determining the feedback power of the power battery of the electric automobile at the current moment according to the voltage value and the current value of the electric automobile at the current moment;
and the third determining unit is used for determining the braking energy feedback efficiency of the electric automobile at the current moment according to the vehicle braking power and the power battery feedback power of the electric automobile at the current moment.
Preferably, the first determining unit is specifically configured to: determining the total braking force of the vehicle at the current moment by the following formula:
Figure BDA0003501073410000031
determining the vehicle braking power according to the following formula:
Pb(k)＝Fb(k)v(k)
wherein, Fb(k) Representing the braking force of a vehicle at the kth moment, k representing the kth sampling moment, theta representing the slope angle of the road surface, mu representing the rolling friction coefficient, m representing the total mass of the electric automobile, g representing the gravity acceleration of the electric automobile, v representing the running speed of the electric automobile at the kth sampling moment, a representing the acceleration of the electric automobile at the kth sampling moment, rho representing the rolling friction factor between the electric automobile tire and the running road surface, A representing the direct contact area of the windward side in the running process of the electric automobile, CdV (k) represents the driving speed of the electric vehicle at the k-th sampling time, Pb(k) To representVehicle braking power at the kth sampling time
Preferably, the second determining unit is specifically configured to: determining the feedback power of the power battery of the electric automobile according to the following formula:
PB(k)＝Ui(k)Ii(k)
the third determining unit is specifically configured to: determining the braking energy feedback efficiency of the electric automobile at the current moment according to the following formula:
Figure BDA0003501073410000041
wherein, PB(k) Represents the feedback power of the power battery of the electric automobile at the kth sampling moment Ui(k) Represents the real-time voltage value, I, fed back by the vehicle power battery at the k-th sampling momenti(k) Representing the real-time current value fed back by the vehicle power battery at the kth sampling moment; pb(k) Representing the vehicle braking power, η, at the kth sampling instantbAnd representing the braking energy feedback efficiency of the electric automobile at the kth sampling moment.
An embodiment of the present invention provides an electric vehicle, including:
one or more processors;
a memory for storing one or more programs;
when the one or more programs are executed by the one or more processors, the one or more processors are enabled to implement the braking energy feedback efficiency determination method as described in any one of the above.
An embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the method for determining braking energy feedback efficiency as described in any one of the above.
The embodiment of the invention provides a method and a device for determining braking energy feedback efficiency, an electric vehicle and a storage medium, wherein the method comprises the following steps: at each sampling moment, acquiring the total mass, the speed, the acceleration, the voltage value and the current value of the electric automobile at the current moment; determining the total braking force and the braking power of the electric vehicle at the current moment according to the total mass, the speed and the acceleration of the electric vehicle at the current moment; determining the feedback power of the power battery of the electric automobile at the current moment according to the voltage value and the current value of the electric automobile at the current moment; and determining the braking energy feedback efficiency of the electric automobile at the current moment according to the vehicle braking power and the power battery feedback power of the electric automobile at the current moment. The method does not need to obtain complex parameters such as energy consumed by wind resistance and rolling resistance which are difficult to measure and calculate. Compared with the existing method, the method needs relatively fewer parameter values, avoids the use of sensors in a large range to a certain extent, controls the number and the types of the sensors in a relatively fewer range, and reduces the calculation complexity and the calculation cost; moreover, the method jumps out of the inherent mode of brake feedback efficiency calculation, reduces the number of step-by-step transmission of calculation errors to a certain extent, and improves the calculation precision; further, the method provided by the embodiment of the invention can obtain real-time data of the braking energy feedback efficiency on the premise of reducing the measurement and calculation difficulty, reducing the measurement and calculation cost, improving the measurement and calculation precision and the like, so that a more excellent method for calculating the braking energy feedback efficiency of the electric vehicle is obtained.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of a braking energy feedback efficiency determination method provided in an embodiment of the present invention;
FIG. 2 is a schematic diagram of simulation results provided by an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a braking energy feedback efficiency determining apparatus according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of an electric vehicle according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The conventional mainstream braking energy feedback efficiency calculation method can be generally divided into the following aspects.
The first kind of calculation method has the main idea of indirectly measuring various parameters influencing the feedback efficiency, namely measuring the feedback voltage value and the feedback current value generated by the braking of the motor of the electric automobile by using a sensor and calculating the total mechanical energy consumption of the braking, and then calculating the actual feedback energy of the braking by using the integral of the product of the measured voltage and current so as to calculate the energy recovery efficiency. For example, in a model for establishing a braking energy recovery efficiency index introduced in the patent "method for estimating the braking energy recovery rate of an electric vehicle", a basic idea and a calculation process are generally similar to those methods, and besides, two methods for calculating the vehicle running resistance are introduced, one is a sliding energy variation method (a fitted curve of speed and vehicle running resistance is obtained through a large number of experiments), and the other is a theoretical calculation method (various resistance values are added). The method is also adopted when a braking energy recovery efficiency index model is established, and although the influence of energy conversion of more parts such as a motor controller, a motor, a transmission system and the like on a calculation result is considered, the basic idea and the calculation process are approximately the same as those of the method. The method for acquiring each parameter and the specific implementation scheme are described in detail on the basis of using the method in the document of 'test research on a certain electric vehicle braking energy recovery detection system', firstly sensors (including a current sensor, a voltage sensor, a shaft rotating speed and torque sensor, a vehicle speed sensor, a pedal force sensor and the like) for acquiring the parameters are installed on an electric vehicle, then the required parameters are acquired by carrying out actual operation experiments on a real road, and finally the braking energy feedback efficiency of the electric vehicle is calculated by using the parameters.
The second kind of calculation method has the main idea of avoiding the measurement of complex parameters, selecting more conveniently obtained parameters to replace calculation or improving calculation algorithm, which does not follow the traditional mode on the algorithm (obtaining voltage and current values to calculate integral, obtaining automobile driving resistance energy consumption and further calculating braking energy feedback efficiency). For example, the patent "method for estimating the recovery rate of braking energy of an electric vehicle" calculates the recovery rate of braking energy by using the braking pressure of a wheel cylinder. The method firstly measures the friction braking torque of the whole vehicle under the condition of closing and opening the braking energy recovery function. Then calculating the braking energy recovered by the motor by using the difference value of the friction braking torque of the whole vehicle under the condition of closing the braking energy recovery function and the friction braking torque of the whole vehicle under the condition of opening the braking energy recovery function; in the patent 'a method for testing the braking energy recovery rate of a pure electric vehicle', corresponding sensors are assembled on the electric vehicle to obtain pressure signals and wheel rotation speed signals, and then the feedback efficiency is calculated by utilizing the parameters; in the literature, "evaluation method for braking energy recovery system of electric vehicle" research, when a testing platform for braking energy recovery system is built, the acquisition of resistance parameters is omitted, that is, the parameter values of resistance energy consumption are not used in calculation, and instead, parameters such as left and right half axle torques, left and right half axle strains, rotation speeds of left and right driving wheels, left and right half axle torque calibration coefficients and the like are used. Then, the originally reserved parameter values and the newly replaced parameter values are utilized to calculate the charging energy of the driving battery, the half-axle braking recovery energy and the vehicle kinetic energy variation according to the formula given in the text. Calculating the braking energy recovery efficiency according to a formula provided in the text; the document 'pure electric vehicle energy feedback efficiency characteristic test analysis' also provides an energy feedback efficiency prediction model construction method. The document indicates that factors such as the motor rotation speed, the torque and the battery pack SOC affect the calculation of the energy feedback efficiency, but it is difficult to obtain parameters of the motor and the battery pack through theoretical analysis, but curve fitting can be performed through a large amount of experimental data to obtain the parameters. Therefore, in the literature, "test analysis of energy feedback efficiency characteristics of pure electric vehicles" a fourth-order polynomial is adopted to fit the battery braking energy feedback efficiency, and the coupling relation of the parameters is substituted into a formula given in the text to calculate the battery braking energy feedback efficiency.
The first type of calculation method has a problem that the conventional method is used for calculating the braking energy feedback efficiency of the electric vehicle on the premise of acquiring parameters which are not easy to acquire, such as voltage, current and energy consumed by resistance (air resistance and rolling resistance) generated by re-braking. This requires specialized sensors to be deployed from both the interior and exterior of the vehicle to obtain the required parameter values, a process that is inconvenient and presents a significant safety hazard. In addition, part of the method calculates the comprehensive feedback efficiency of the braking process, rather than the real-time feedback efficiency of the braking process, which is difficult to use in optimizing the regenerative braking control strategy. In addition to the above-mentioned common problems, there are also the following individual problems: the literature 'evaluation method research of a pure electric vehicle braking energy recovery system' provides two schemes for solving vehicle running resistance, but the finally required vehicle running resistance energy consumption value also needs to be subjected to a series of operations on the basis of obtaining the resistance value, so that the calculation error is accumulated and enlarged, the calculation of the method is complex on one hand, and the precision of the braking energy feedback efficiency calculation result is reduced on the other hand; on the basis of the research of the pure electric vehicle braking energy recovery efficiency test method, the influence of more energy consumption of a motor controller, a motor, a transmission system and the like on a calculation result is additionally considered for improving the calculation accuracy, but the addition of more influence parameters means the increase of the calculation efficiency (the complexity of the calculation method) and the calculation cost; the literature "experimental research on a certain electric vehicle braking energy recovery detection system" introduces a parameter value acquisition process, wherein a sensor for acquiring a parameter value is firstly installed on an electric vehicle, and then experimental tests are carried out on a real road to acquire a required parameter value. From this we can see that more experimental parameters mean that more number and more kinds of sensors are used, not only increasing the complexity of the braking energy feedback efficiency calculation process, but also increasing the hardware cost of the calculation process to some extent.
The second method is an improvement on the conventional method, and the original parameter values which are not convenient to obtain are replaced by the parameters which are relatively better obtained, or other algorithms are used for calculation. On the one hand, the method jumps out of the constraint of the inherent mode to seek a simpler and reasonable calculation method, and on the other hand, the method also effectively solves the problem of the first method. But there are also some disadvantages: for example, the related method measures the corresponding friction braking torque in the closing state and the opening state of the braking energy feedback system respectively, so that the whole calculation process becomes complicated, time-consuming and labor-consuming; the method related to the 'method for testing the recovery rate of braking energy of the pure electric vehicle' has the problems that sensors for measuring the parameter values need to be newly adapted to the electric vehicle, and more sensors are used, so that the complexity of the calculation process of the feedback efficiency of the braking energy is increased, and the cost of the calculation process is increased to a certain extent; the problem of the research of the evaluation method of the braking energy recovery system of the electric automobile in the literature is basically consistent with the problem of the research of the braking energy recovery rate test method of the pure electric automobile in the patent, and the research of the evaluation method of the braking energy recovery system of the electric automobile in the literature is that the resistance energy consumption value of the automobile in the driving process is replaced by parameters such as the torque of a left half shaft and a right half shaft, the strain of the left half shaft and the right half shaft, the rotating speed of a left driving wheel and a right driving wheel, the torque calibration coefficients of the left half shaft and the right half shaft and the like, but more parameter values are relatively increased, and the more parameter values mean that more sensors are added and used, so the calculation cost and the calculation complexity are increased; the document 'pure electric vehicle energy feedback efficiency characteristic test analysis' provides a method for fitting the battery braking energy feedback efficiency by a fourth-order polynomial, and although the method can well fit the functional relationship between the number of test working condition points and the energy feedback efficiency, the curve fitting needs to acquire a large amount of experimental data through experiments, so that the calculation process becomes more complicated and the calculation period becomes longer. And the actual situation is required to be basically consistent with the curve fitting result under the same environment as the data acquisition, otherwise, the feedback efficiency under the actual road is different from the curve fitting result.
Summarizing the current mainstream methods, the main problems mainly exist in the following aspects:
and part of parameters are difficult to obtain, so that the calculation difficulty of the feedback efficiency is increased.
Excessive measurement parameters result in a large number of sensors used, increasing the computational cost and complexity of feedback efficiency.
The calculation error of each step is transferred to the next step by step, and the complicated algorithm or multi-step algorithm can lead the accumulation of the calculation error to be enlarged and reduce the calculation precision.
The curve fitting parameters or results need to measure a large amount of experimental data in an ideal environment, so that the calculation period is prolonged, and the calculation result precision under complex and real road conditions is reduced.
The braking energy falling efficiency calculated by part of the methods is comprehensive efficiency, not real-time efficiency, which is not beneficial to designing a regenerative braking real-time control strategy.
Based on the above problems, an embodiment of the present invention provides a method for determining a braking energy feedback efficiency, fig. 1 is a schematic flow chart of the method for determining a braking energy feedback efficiency provided in an embodiment of the present invention, and as shown in fig. 1, the method mainly includes the following steps:
step 101, acquiring the total mass, the speed, the acceleration, the voltage value and the current value of the electric automobile at the current moment at each sampling moment;
102, determining the total braking force and the braking power of the vehicle at the current moment according to the total mass, the speed and the acceleration of the electric vehicle at the current moment;
103, determining the feedback power of the power battery of the electric automobile at the current moment according to the voltage value and the current value of the electric automobile at the current moment;
and 104, determining the braking energy feedback efficiency of the electric automobile at the current moment according to the vehicle braking power and the power battery feedback power of the electric automobile at the current moment.
In step 101, at each sampling time, the On-Board Diagnostics (On-Board Diagnostics) interface of the electric vehicle collects the operation data of the electric vehicle, and further, the OBD decoding analyzer can directly output the total mass of the electric vehicle, the vehicle speed at the current time, the acceleration at the current time, and the voltage value and the current value fed back by the power battery at the current time.
In step 102, the total braking force of the vehicle at the present time is determined by the following formula:
Figure BDA0003501073410000091
wherein, Fb(k) Representing the braking force of a vehicle at the kth moment, k representing the kth sampling moment, theta representing the slope angle of the road surface, mu representing the rolling friction coefficient, m representing the total mass of the electric automobile, g representing the gravity acceleration of the electric automobile, v representing the running speed of the electric automobile at the kth sampling moment, a representing the acceleration of the electric automobile at the kth sampling moment, rho representing the rolling friction factor between the electric automobile tire and the running road surface, A representing the direct contact area of the windward side in the running process of the electric automobile, CdIs the air resistance coefficient.
Further, the vehicle braking power is determined according to the following formula:
Pb(k)＝Fb(k)v(k)
wherein, Fb(k) V (k) represents the vehicle braking force at the k-th sampling time, v (k) represents the driving speed of the electric vehicle at the k-th sampling time, Pb(k) The vehicle braking power at the kth sampling instant is indicated.
In step 103, the feedback power of the power battery of the electric vehicle is determined according to the following formula:
PB(k)＝Ui(k)Ii(k)
wherein, PB(k) Represents the feedback power of the power battery of the electric automobile at the kth sampling moment Ui(k) Represents the real-time voltage value, I, fed back by the vehicle power battery at the k-th sampling momenti(k) And the real-time current value fed back by the vehicle power battery at the kth sampling moment is represented.
In step 104, the braking energy feedback efficiency of the electric vehicle at the current moment is determined according to the following formula:
Figure BDA0003501073410000101
wherein, PB(k) Represents the feedback power P of the power battery of the electric automobile at the k sampling momentb(k) Representing the vehicle braking power, η, at the kth sampling instantbAnd representing the braking energy feedback efficiency of the electric automobile at the kth sampling moment.
Fig. 2 is a schematic diagram of a simulation experiment result provided by the embodiment of the present invention, and it can be seen from the result in the diagram that the braking efficiency of the pure electric vehicle in the braking process, which is obtained by calculation by the determination method provided by the embodiment of the present invention, is approximately concentrated in 40% to 70%. The simulation result basically accords with the actual situation of the braking efficiency of the pure electric vehicle, and shows that the algorithm provided by the embodiment of the invention has better calculation precision for calculating the braking efficiency of the pure electric vehicle.
Fig. 3 is a schematic structural diagram of a braking energy feedback efficiency determining apparatus provided in an embodiment of the present invention, where the apparatus is configured to execute the braking energy feedback efficiency determining method provided in any of the embodiments. The device and the method for determining the braking energy feedback efficiency of each embodiment belong to the same inventive concept, and details which are not described in detail in the embodiment of the device for determining the braking energy feedback efficiency can refer to the embodiment of the method for determining the braking energy feedback efficiency. As shown in fig. 3, the apparatus includes an acquisition unit 201, a first determination unit 202, a second determination unit 203, and a third determination unit 204.
The acquiring unit 201 is used for acquiring the total mass, the speed, the acceleration, the voltage value and the current value of the electric automobile at the current moment at each sampling moment;
the first determining unit 202 is used for determining the total braking force and the braking power of the vehicle at the current moment according to the total mass, the vehicle speed and the acceleration of the electric vehicle at the current moment;
the second determining unit 203 is configured to determine the feedback power of the power battery of the electric vehicle at the current moment according to the voltage value and the current value of the electric vehicle at the current moment;
and a third determining unit 204, configured to determine braking energy feedback efficiency of the electric vehicle at the current time according to the vehicle braking power of the electric vehicle and the power battery feedback power at the current time.
Preferably, the first determining unit 202 is specifically configured to: determining the total braking force of the vehicle at the current moment by the following formula:
Figure BDA0003501073410000111
determining the vehicle braking power according to the following formula:
Pb(k)＝Fb(k)v(k)
wherein, Fb(k) Representing the braking force of a vehicle at the kth moment, k representing the kth sampling moment, theta representing the slope angle of the road surface, mu representing the rolling friction coefficient, m representing the total mass of the electric automobile, g representing the gravity acceleration of the electric automobile, v representing the running speed of the electric automobile at the kth sampling moment, a representing the acceleration of the electric automobile at the kth sampling moment, rho representing the rolling friction factor between the electric automobile tire and the running road surface, A representing the direct contact area of the windward side in the running process of the electric automobile, CdV (k) represents the driving speed of the electric vehicle at the k-th sampling time, Pb(k) Indicating the vehicle braking power at the k-th sampling instant
Preferably, the second determining unit 203 is specifically configured to: determining the feedback power of the power battery of the electric automobile according to the following formula:
PB(k)＝Ui(k)Ii(k)
the third determining unit 204 is specifically configured to: determining the braking energy feedback efficiency of the electric automobile at the current moment according to the following formula:
Figure BDA0003501073410000121
wherein, PB(k) Represents the feedback power of the power battery of the electric automobile at the kth sampling moment Ui(k) Represents the real-time voltage value, I, fed back by the vehicle power battery at the k-th sampling momenti(k) Representing the real-time current value fed back by the vehicle power battery at the kth sampling moment; pb(k) And the braking power of the vehicle at the kth sampling moment is represented, and eta b represents the braking energy feedback efficiency of the electric vehicle at the kth sampling moment.
It should be understood that the above braking energy feedback efficiency determination apparatus includes only units that are logically divided according to the functions implemented by the device apparatus, and in practical applications, the above units may be stacked or split. The functions implemented by the braking energy feedback efficiency determining apparatus provided in this embodiment correspond to the braking energy feedback efficiency determining methods provided in the above embodiments one to one, and for a more detailed processing flow implemented by the apparatus, detailed description is already made in the above method embodiment one, and detailed description is not given here.
Fig. 4 is a schematic structural diagram of an electric vehicle according to an embodiment of the present invention, and as shown in fig. 4, the electric vehicle includes a memory 310, a processor 320, an input device 330, and an output device 340. The number of the processors 320 in the electric vehicle may be one or more, and one processor 320 is taken as an example in fig. 4; the memory 310, the processor 320, the input device 330, and the output device 340 in the electric vehicle may be connected by a bus or other means, and are exemplified by a bus 350 in fig. 4.
The memory 310 is a computer-readable storage medium, and can be used for storing software programs, computer-executable programs, and modules, such as program instructions/modules corresponding to the remaining mileage determining method in the embodiment of the present invention (for example, the braking energy feedback efficiency determining apparatus includes the area acquiring unit 201, the first determining unit 202, the second determining unit 203, and the third determining unit 204). The processor 320 executes various functional applications and data processing of the electric vehicle by executing software programs, instructions and modules stored in the memory 310, that is, implements the remaining mileage determining method described above.
The memory 310 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application program required for at least one function; the storage data area may store data created according to the use of the electric vehicle, and the like. Further, the memory 310 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some examples, memory 310 may further include memory located remotely from processor 320, which may be connected to devices through a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The input device 330 may be used to receive input numeric or character information and generate key signal inputs related to user settings and function controls of the device. The output device 340 may include a display device such as a display screen.
Embodiments of the present invention provide a storage medium containing computer-executable instructions, which when executed by a computer processor, are configured to perform a method for determining braking energy feedback efficiency, where the method may include:
at each sampling moment, acquiring the total mass, the speed, the acceleration, the voltage value and the current value of the electric automobile at the current moment;
determining the total braking force and the braking power of the electric vehicle at the current moment according to the total mass, the speed and the acceleration of the electric vehicle at the current moment;
determining the feedback power of the power battery of the electric automobile at the current moment according to the voltage value and the current value of the electric automobile at the current moment;
and determining the braking energy feedback efficiency of the electric automobile at the current moment according to the vehicle braking power and the power battery feedback power of the electric automobile at the current moment.
Of course, the storage medium containing the computer-executable instructions provided by the embodiments of the present invention is not limited to the method operations described above, and may also perform related operations in a remaining mileage prediction method provided by any embodiments of the present invention.
In summary, embodiments of the present invention provide a method and an apparatus for determining braking energy feedback efficiency, an electric vehicle, and a storage medium, where the method includes: at each sampling moment, acquiring the total mass, the speed, the acceleration, the voltage value and the current value of the electric automobile at the current moment; determining the total braking force and the braking power of the electric vehicle at the current moment according to the total mass, the speed and the acceleration of the electric vehicle at the current moment; determining the feedback power of the power battery of the electric automobile at the current moment according to the voltage value and the current value of the electric automobile at the current moment; and determining the braking energy feedback efficiency of the electric automobile at the current moment according to the vehicle braking power and the power battery feedback power of the electric automobile at the current moment. The method does not need to obtain complex parameters such as energy consumed by wind resistance and rolling resistance which are difficult to measure and calculate. Compared with the existing method, the method needs relatively fewer parameter values, avoids the use of sensors in a large range to a certain extent, controls the number and the types of the sensors in a relatively fewer range, and reduces the calculation complexity and the calculation cost; moreover, the method jumps out of the inherent mode of brake feedback efficiency calculation, reduces the number of step-by-step transmission of calculation errors to a certain extent, and improves the calculation precision; further, the method provided by the embodiment of the invention can obtain real-time data of the braking energy feedback efficiency on the premise of reducing the measurement and calculation difficulty, reducing the measurement and calculation cost, improving the measurement and calculation precision and the like, so that a more excellent method for calculating the braking energy feedback efficiency of the electric vehicle is obtained.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (10)

1. The braking energy feedback efficiency determination method is characterized by comprising the following steps:
at each sampling moment, acquiring the total mass, the speed, the acceleration, the voltage value and the current value of the electric automobile at the current moment;
determining the total braking force and the braking power of the electric vehicle at the current moment according to the total mass, the speed and the acceleration of the electric vehicle at the current moment;
determining the feedback power of the power battery of the electric automobile at the current moment according to the voltage value and the current value of the electric automobile at the current moment;
and determining the braking energy feedback efficiency of the electric automobile at the current moment according to the vehicle braking power and the power battery feedback power of the electric automobile at the current moment.
2. The method of claim 1, wherein the total vehicle braking force at the present time is determined by the following equation:
Figure FDA0003501073400000011
wherein, Fb(k) Representing the braking force of a vehicle at the kth moment, k representing the kth sampling moment, theta representing the slope angle of the road surface, mu representing the rolling friction coefficient, m representing the total mass of the electric automobile, g representing the gravity acceleration of the electric automobile, v representing the running speed of the electric automobile at the kth sampling moment, a representing the acceleration of the electric automobile at the kth sampling moment, rho representing the rolling friction factor between the electric automobile tire and the running road surface, A representing the direct contact area of the windward side in the running process of the electric automobile, CdIs the air resistance coefficient.
3. A method according to claim 1, characterized in that the vehicle braking power is determined according to the following formula:
Pb(k)＝Fb(k)v(k)
wherein, Fb(k) V (k) represents the vehicle braking force at the k-th sampling time, v (k) represents the driving speed of the electric vehicle at the k-th sampling time, Pb(k) The vehicle braking power at the kth sampling instant is indicated.
4. The method of claim 1, wherein the feedback power of the power cell of the electric vehicle is determined according to the following equation:
PB(k)＝Ui(k)Ii(k)
wherein, PB(k) Represents the feedback power of the power battery of the electric automobile at the kth sampling moment Ui(k) Represents the real-time voltage value, I, fed back by the vehicle power battery at the k-th sampling momenti(k) And the real-time current value fed back by the vehicle power battery at the kth sampling moment is represented.
5. The method of claim 1, wherein the braking energy feedback efficiency of the electric vehicle at the current moment is determined according to the following formula:
Figure FDA0003501073400000021
wherein, PB(k) Represents the feedback power P of the power battery of the electric automobile at the k sampling momentb(k) Representing the vehicle braking power, η, at the kth sampling instantbAnd representing the braking energy feedback efficiency of the electric automobile at the kth sampling moment.
6. Braking energy repayment efficiency determining means, its characterized in that includes:
the acquisition unit is used for acquiring the total mass, the speed, the acceleration, the voltage value and the current value of the electric automobile at the current moment at each sampling moment;
the first determining unit is used for determining the total braking force and the braking power of the vehicle at the current moment according to the total mass, the vehicle speed and the acceleration of the electric vehicle at the current moment;
the second determining unit is used for determining the feedback power of the power battery of the electric automobile at the current moment according to the voltage value and the current value of the electric automobile at the current moment;
and the third determining unit is used for determining the braking energy feedback efficiency of the electric automobile at the current moment according to the vehicle braking power and the power battery feedback power of the electric automobile at the current moment.
7. The apparatus of claim 6, wherein the first determining unit is specifically configured to: determining the total braking force of the vehicle at the current moment by the following formula:
Figure FDA0003501073400000022
determining the vehicle braking power according to the following formula:
Pb(k)＝Fb(k)v(k)
wherein, Fb(k) Representing the braking force of a vehicle at the kth moment, k representing the kth sampling moment, theta representing the slope angle of the road surface, mu representing the rolling friction coefficient, m representing the total mass of the electric automobile, g representing the gravity acceleration of the electric automobile, v representing the running speed of the electric automobile at the kth sampling moment, a representing the acceleration of the electric automobile at the kth sampling moment, rho representing the rolling friction factor between the electric automobile tire and the running road surface, A representing the direct contact area of the windward side in the running process of the electric automobile, CdV (k) represents the driving speed of the electric vehicle at the k-th sampling time, Pb(k) The vehicle braking power at the kth sampling instant is indicated.
8. The apparatus of claim 6, wherein the second determining unit is specifically configured to: determining the feedback power of the power battery of the electric automobile according to the following formula:
PB(k)＝Ui(k)Ii(k)
the third determining unit is specifically configured to: determining the braking energy feedback efficiency of the electric automobile at the current moment according to the following formula:
Figure FDA0003501073400000031
wherein, PB(k) Represents the feedback power of the power battery of the electric automobile at the kth sampling moment Ui(k) Represents the real-time voltage value, I, fed back by the vehicle power battery at the k-th sampling momenti(k) Representing the real-time current value fed back by the vehicle power battery at the kth sampling moment; pb(k) Representing the vehicle braking power, η, at the kth sampling instantbAnd representing the braking energy feedback efficiency of the electric automobile at the kth sampling moment.
9. An electric vehicle, comprising:
one or more processors;
a memory for storing one or more programs;
when the one or more programs are executed by the one or more processors, the one or more processors are enabled to implement the braking energy feedback efficiency determination method as claimed in any one of claims 1 to 5.
10. A computer-readable storage medium, on which a computer program is stored, wherein the computer program, when being executed by a processor, implements the braking energy feedback efficiency determination method according to any one of claims 1 to 5.
CN202210127494.4A 2022-02-11 2022-02-11 Braking energy feedback efficiency determination method and device, electric vehicle and storage medium Pending CN114407667A (en)

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