阅读说明：本技术 一种纯电动汽车电池组soc在线估值方法 (SOC (state of charge) online estimation method for battery pack of pure electric vehicle ) 是由 何洪文 周稼铭 魏中宝 衣丰艳 彭剑坤 衣杰 于 2019-11-11 设计创作，主要内容包括：本发明公开了一种纯电动汽车电池组SOC在线估值方法,包括如下步骤：路况信息检查→构建准稳态过程典型行驶工况→能量构建和优化管理→执行控制→电池组SOC估算。路况信息检查：首先检测人员通过GPS检测道路信息,检查道路是否拥堵。本发明通过近年来随着智能交通和动力电池技术的发展,根据实际道路行驶工况数据进行纯电动汽车行驶工况构建和预测,同时结合电池建模和状态估计方法,对纯电动汽车能量耗散过程进行优化管理,本发明的实施将为提高纯电动汽车的经济性和使用寿命提供可行的解决途径,实现电动汽车在复杂行驶条件下高效平稳运行,降低了一定的电动汽车能耗,延长了续驶里程,保证了纯电动汽车的使用。(The invention discloses a battery pack SOC online estimation method of a pure electric vehicle, which comprises the following steps: road condition information inspection → construction of a quasi-steady state process typical driving condition → energy construction and optimization management → execution control → battery pack SOC estimation. And (3) checking road condition information: firstly, a detector detects road information through a GPS and checks whether the road is congested. The invention constructs and predicts the running condition of the pure electric vehicle according to the running condition data of the actual road along with the development of intelligent transportation and power battery technology in recent years, and simultaneously optimally manages the energy dissipation process of the pure electric vehicle by combining a battery modeling and state estimation method.)

1. The method for estimating the SOC of the battery pack of the pure electric vehicle on line is characterized by comprising the following steps: the method is applied to the battery-level and super-capacitor-driven pure electric vehicle, and comprises the following steps: road condition information inspection → construction of a quasi-steady state process typical driving condition → energy construction and optimization management → execution control → battery pack SOC estimation.

2. The SOC online estimation method for the battery pack of the pure electric vehicle according to claim 1, characterized in that: the road condition information detection specifically comprises the steps of,

firstly, a detector detects road information through a GPS (global positioning system), checks whether a road is congested or not, simultaneously checks whether gaps and pits exist in the road or not, acquires and processes basic road data of a driving experiment based on a GPS/GPRS (global positioning system/general packet radio service) vehicle-mounted data acquisition device, and simultaneously acquires characteristic information of driving conditions such as a track, a displacement and a speed of a vehicle.

3. The SOC online estimation method for the battery pack of the pure electric vehicle according to claim 1, characterized in that:

constructing a quasi-steady state process typical driving condition: collecting actual road running condition data of the pure electric vehicle, extracting kinematic segments, extracting and classifying the characteristic values of the kinematic segments based on a principal component analysis and cluster analysis method, extracting representative running conditions by using correlation coefficients, constructing a comprehensive working condition conforming to the running condition characteristics of the pure electric vehicle, introducing multi-time scale kinematic parameters for describing quasi-steady-state characteristics of the running state in a kinematic segment class, and switching processes among different kinematic segments in order to meet the requirement of energy online optimization management of the running state obtained in real time in the running process of the pure electric vehicle, adopting a dimension reduction processing and fuzzy clustering method, performing secondary clustering on the segments in the segment class by using the kinematic parameters as characteristic parameters, realizing extraction and combination of the characteristic segments in the class, and completing construction of the typical running condition of the pure electric vehicle in the quasi-steady-state process, and establishing off-line and on-line kinematic segment feature extraction and classification criteria, wherein the running state of the pure electric vehicle presents a random continuous characteristic.

4. The SOC online estimation method for the battery pack of the pure electric vehicle according to claim 3, characterized in that: and B, when the vehicle runs under the working condition in the step B, after the kinematics segment feature extraction and classification criteria under the comprehensive working condition and the quasi-steady state are formulated, the statistical characteristics of a random process are obtained, and the working condition data are subjected to state division, model event classification and model event set determination to obtain a running state transition matrix under the comprehensive working condition and the quasi-steady state working condition.

5. The SOC online estimation method for the battery pack of the pure electric vehicle according to claim 1, characterized in that:

the energy construction and the optimal management particularly comprise,

a. introducing a hierarchical control principle to establish a pure electric vehicle energy management system, wherein the control system comprises two levels of control strategies, the top level strategy is an energy management strategy, an energy optimization management model is established by adopting a Markov decision theory and is responsible for monitoring the energy flow of the whole pure electric vehicle power system, the target power of a motor is determined according to the current state of the system, the bottom level strategy is an execution control layer, and power distribution and motor control are carried out according to the current state of the system so as to meet the power requirement of the pure electric vehicle;

b. the method comprises the steps of taking the optimal energy consumption of a pure electric vehicle in the whole comprehensive working condition interval as a target under the comprehensive working condition, taking the optimal comprehensive dynamics and economy of the pure electric vehicle under the quasi-steady working condition as a target, taking the current state of the electric vehicle as a constraint condition, establishing a random dynamic programming optimization proposition based on a Markov decision theory and solving the problem, integrating the optimization proposition into a Markov decision process with a limited domain based on a driving state transition probability matrix, solving the problem by a bottom-up recursion method, adopting a processing mode of discrete solution online table lookup, traversing all possible initial values during offline solution, storing the result in a table, and directly obtaining the current optimal control vector value in the table lookup mode during online operation.

6. A pure electric vehicle battery pack SOC online estimation method according to any one of claims 1-5, characterized in that:

the execution of the control specifically includes,

in the driving process of a vehicle, a sensor acquires the speed U, the acceleration a, the SOC of a battery pack and the terminal voltage U of a super capacitor of the electric vehicle in real time, firstly, the working state of the battery and the super capacitor is judged according to the SOC and the terminal voltage U of the super capacitor, then, the system is judged to enter a single-drive mode or a double-drive mode or a pre-charge mode according to the obtained working state, the real-time speed and the acceleration, and if the system enters the single-drive mode, the output of the super capacitor is stopped, so that the battery pack supplies; if the battery enters the double-drive mode, the output power of the battery pack is adjusted according to the optimal output power of the battery corresponding to the working state; if the super capacitor enters the pre-charging mode, the super capacitor is charged by pulse, so that the energy receiving rate and the energy efficiency of the super capacitor are improved to the maximum extent.

7. The SOC online estimation method for the battery pack of the pure electric vehicle according to claim 6, characterized in that: when the step executes control, the energy management controller is set to be in a low-voltage working state once the boundary voltage lower than 35V is collected at a certain moment, the voltage signal collection is temporarily stopped, and the voltage signal collection is kept for a period of time until the brake signal arrives.

8. The SOC online estimation method for the battery pack of the pure electric vehicle according to claim 1, characterized in that: the battery pack SOC estimation includes,

by establishing an efficiency model of the electric automobile power system, the change rule of the efficiency of the electric automobile power system under three working modes of single driving of the battery pack, common driving of the battery pack and the super capacitor and pre-charging of the super capacitor by the battery pack is analyzed on the basis of theoretical modeling, a control strategy for enabling the electric automobile to reasonably switch the working modes along with the driving working condition is researched by taking the optimal efficiency as a target, and the control effect of the control strategy is analyzed.

9. The SOC online estimation method for the battery pack of the pure electric vehicle according to claim 8, wherein: the SOC estimation of the battery pack further comprises the steps of calculating the driving efficiency of a power system of the battery pack, a super capacitor and motor loss under different vehicle speeds and accelerations by adopting a reverse modeling method, completing SOC and SOH estimation algorithm verification tests by adopting a battery pack testing system, developing a battery state estimation algorithm by adopting a Battery Management System (BMS) hardware-in-loop simulation platform, loading an established battery pack model to the BMS hardware-in-loop simulation platform, acquiring voltage, current and temperature information of a single battery in real time by utilizing a data acquisition board card, estimating the SOC state and capacity of the battery pack based on the developed SOC and SOH estimation algorithms, and verifying the accuracy and efficiency of the algorithms.

10. The battery pack SOC online estimation method for the pure electric vehicle according to claim 9, wherein: and when the SOC of the battery pack is estimated, a battery simulator is adopted to perform battery pack testing under a pulse cycle discharge working condition, parameters in the established equivalent circuit model of the battery pack are identified, and the battery simulator is used to perform characteristic testing and theoretical model verification on the super capacitor.

Technical Field

The invention relates to the technical field of electric automobiles, in particular to an SOC (state of charge) online estimation method for a battery pack of a pure electric automobile.

Background

The electric automobile is a vehicle which uses a vehicle-mounted power supply as power and drives wheels by a motor, meets various requirements of road traffic and safety regulations, has a smaller environmental impact relative to the traditional automobile, has a wide prospect, but is immature in the prior art, and is of the type: pure electric vehicles, hybrid vehicles, fuel cell vehicles.

In order to deal with the problems of energy shortage and environmental pollution, the development of new energy automobiles is more and more concerned by governments and society of various countries, pure electric automobiles have the outstanding advantages of high efficiency, zero emission and the like, and are one of the important directions of automobile development, but the performance of power batteries still has technical bottlenecks at the present stage, the driving range of the pure electric automobiles is obviously reduced along with the decline of the performance of the power batteries, especially under the urban driving working conditions of frequent starting, acceleration, braking and the like, the energy consumption of the electric automobiles is increased, the driving range is obviously shortened, the use of the pure electric automobiles is seriously limited, how to reasonably adjust the energy distribution of the electric automobiles under the complex road conditions, reduce the energy consumption of the whole automobiles and prolong the driving range of the pure electric automobiles is a main problem concerned by the industry and students.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides an online SOC estimation method for a battery pack of a pure electric vehicle, which has the advantage of realizing efficient and stable running of the electric vehicle under complex running conditions and solves the problems in the background art.

(II) technical scheme

In order to achieve the purpose, the invention provides the following technical scheme: a battery pack SOC online estimation method of a pure electric vehicle is applied to the pure electric vehicle driven by a battery level and a super capacitor, and comprises the following steps: road condition information inspection → construction of a quasi-steady state process typical driving condition → energy construction and optimization management → execution control → battery pack SOC estimation.

The method for estimating SOC of battery pack of blade electric vehicle on line as described above, wherein optionally, the road condition information detection specifically includes,

firstly, a detector detects road information through a GPS (global positioning system), checks whether a road is congested or not, simultaneously checks whether gaps and pits exist in the road or not, acquires and processes basic road data of a driving experiment based on a GPS/GPRS (global positioning system/general packet radio service) vehicle-mounted data acquisition device, and simultaneously acquires characteristic information of driving conditions such as a track, a displacement and a speed of a vehicle.

The method for estimating the SOC of the battery pack of the pure electric vehicle on line as described above, wherein optionally, a quasi-steady-state process typical driving condition is constructed: collecting actual road running condition data of the pure electric vehicle, extracting kinematic segments, extracting and classifying the characteristic values of the kinematic segments based on a principal component analysis and cluster analysis method, extracting representative running conditions by using correlation coefficients, constructing a comprehensive working condition conforming to the running condition characteristics of the pure electric vehicle, introducing multi-time scale kinematic parameters for describing quasi-steady-state characteristics of the running state in a kinematic segment class, and switching processes among different kinematic segments in order to meet the requirement of energy online optimization management of the running state obtained in real time in the running process of the pure electric vehicle, adopting a dimension reduction processing and fuzzy clustering method, performing secondary clustering on the segments in the segment class by using the kinematic parameters as characteristic parameters, realizing extraction and combination of the characteristic segments in the class, and completing construction of the typical running condition of the pure electric vehicle in the quasi-steady-state process, and establishing off-line and on-line kinematic segment feature extraction and classification criteria, wherein the running state of the pure electric vehicle presents a random continuous characteristic.

Optionally, in the method for estimating SOC of battery pack of blade electric vehicle on line, when the vehicle is driven in step B, after the kinematics segment feature extraction and classification criteria under the comprehensive working condition and the quasi-steady state are formulated, statistical characteristics of a random process are obtained, and the state division, the model event classification and the model event set determination are performed on the working condition data to obtain a driving state transition matrix under the comprehensive working condition and the quasi-steady state working condition.

The method for estimating SOC of battery pack of pure electric vehicle on line as described above, wherein, optionally, the energy construction and optimization management specifically includes,

a. introducing a hierarchical control principle to establish a pure electric vehicle energy management system, wherein the control system comprises two levels of control strategies, the top level strategy is an energy management strategy, an energy optimization management model is established by adopting a Markov decision theory and is responsible for monitoring the energy flow of the whole pure electric vehicle power system, the target power of a motor is determined according to the current state of the system, the bottom level strategy is an execution control layer, and power distribution and motor control are carried out according to the current state of the system so as to meet the power requirement of the pure electric vehicle;

b. the method comprises the steps of taking the optimal energy consumption of a pure electric vehicle in the whole comprehensive working condition interval as a target under the comprehensive working condition, taking the optimal comprehensive dynamics and economy of the pure electric vehicle under the quasi-steady working condition as a target, taking the current state of the electric vehicle as a constraint condition, establishing a random dynamic programming optimization proposition based on a Markov decision theory and solving the problem, integrating the optimization proposition into a Markov decision process with a limited domain based on a driving state transition probability matrix, solving the problem by a bottom-up recursion method, adopting a processing mode of discrete solution online table lookup, traversing all possible initial values during offline solution, storing the result in a table, and directly obtaining the current optimal control vector value in the table lookup mode during online operation.

The method for estimating the SOC of the battery pack of the electric vehicle on line as described above, wherein optionally, the performing of the control specifically includes,

in the driving process of a vehicle, a sensor acquires the speed U, the acceleration a, the SOC of a battery pack and the terminal voltage U of a super capacitor of the electric vehicle in real time, firstly, the working state of the battery and the super capacitor is judged according to the SOC and the terminal voltage U of the super capacitor, then, the system is judged to enter a single-drive mode or a double-drive mode or a pre-charge mode according to the obtained working state, the real-time speed and the acceleration, and if the system enters the single-drive mode, the output of the super capacitor is stopped, so that the battery pack supplies; if the battery enters the double-drive mode, the output power of the battery pack is adjusted according to the optimal output power of the battery corresponding to the working state; if the super capacitor enters the pre-charging mode, the super capacitor is charged by pulse, so that the energy receiving rate and the energy efficiency of the super capacitor are improved to the maximum extent.

The method for estimating SOC of battery pack of blade electric vehicle on line as described above, wherein optionally, when the step executes the control, the energy management controller is set to consider to enter the low voltage operating state once the boundary voltage lower than 35V is collected at a certain time, temporarily stop the collection of the voltage signal, and keep for a certain time until the brake signal arrives.

The method for estimating the SOC of the battery pack of the pure electric vehicle on line as described above, wherein, optionally, the estimating of the SOC of the battery pack includes,

by establishing an efficiency model of the electric automobile power system, the change rule of the efficiency of the electric automobile power system under three working modes of single driving of the battery pack, common driving of the battery pack and the super capacitor and pre-charging of the super capacitor by the battery pack is analyzed on the basis of theoretical modeling, a control strategy for enabling the electric automobile to reasonably switch the working modes along with the driving working condition is researched by taking the optimal efficiency as a target, and the control effect of the control strategy is analyzed.

The online estimation method for the battery pack SOC of the pure electric vehicle as described above, wherein optionally, the estimation of the battery pack SOC further includes calculating the driving efficiency of the power system of the battery pack, the super capacitor, and the motor loss at different speeds and accelerations by using a reverse modeling method, the SOC and SOH estimation algorithm verification test is completed by using a battery pack test system, the battery state estimation algorithm is developed by using a Battery Management System (BMS) hardware-in-loop simulation platform, the established battery pack model is loaded to the BMS hardware-in-loop simulation platform, the voltage, current, and temperature information of a single battery is acquired in real time by using a data acquisition board card, the SOC state and capacity of the battery pack are estimated based on the developed SOC and SOH estimation algorithm, and the accuracy and efficiency of the algorithm are verified.

Optionally, in the step of estimating the SOC of the battery pack, a battery simulator is used for testing the battery pack under a pulse cycle discharge working condition, identifying parameters in the established equivalent circuit model of the battery pack, and performing characteristic test and theoretical model verification on the super capacitor through the battery simulator.

(III) advantageous effects

Compared with the prior art, the invention provides an online SOC estimation method for a battery pack of a pure electric vehicle, which has the following beneficial effects:

1. the invention constructs and predicts the running condition of the pure electric vehicle according to the running condition data of the actual road along with the development of intelligent transportation and power battery technology in recent years, and simultaneously optimally manages the energy dissipation process of the pure electric vehicle by combining a battery modeling and state estimation method.

2. Collecting actual road running condition data of the pure electric vehicle, extracting a kinematics segment, extracting and classifying feature values of the kinematics segment based on a principal component analysis and clustering analysis method, constructing a comprehensive working condition which accords with the running condition features of the pure electric vehicle, introducing multi-time scale kinematics parameters for describing quasi-steady-state features of running states in the kinematics segment class, between classes and between different kinematics segments, adopting a dimensionality reduction processing and fuzzy clustering method to complete the typical running condition construction of the quasi-steady-state process of the pure electric vehicle, adopting a least square method to carry out parameter identification on an established lithium ion power battery pack equivalent circuit model, adopting a combined algorithm of extended Kalman filtering and ampere-hour integration to carry out SOC and SOH combined estimation on the lithium ion power battery pack, and providing a hierarchical control theory to establish an energy management system of the pure electric vehicle, the implementation of the invention provides a feasible solution for improving the economy and the service life of the pure electric vehicle and realizes the efficient and stable running of the electric vehicle under the complex running condition.

Drawings

FIG. 1 is a flow chart of the present invention;

FIG. 2 is a flow chart of an on-line estimation algorithm for battery capacity in accordance with the present invention;

FIG. 3 is a schematic diagram of an energy management system based on hierarchical control according to the present invention;

FIG. 4 is a diagram of the integration and solution process of Markov decision proposition based on the present invention;

fig. 5 is a diagram of a battery pack testing system according to 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.

All the components of the present invention are standard components commonly used or known to those skilled in the art, and the structure and principle thereof can be known to those skilled in the art through technical manuals or through routine experimentation.

Referring to fig. 1-5, the invention provides an online estimation method for battery pack SOC of a pure electric vehicle, which is applied to a battery-level and super-capacitor-driven pure electric vehicle and comprises the following steps: road condition information inspection → construction of a typical driving condition in a quasi-steady state process → energy construction and optimization management → execution control → estimation of SOC of a battery pack;

A. and (3) checking road condition information: firstly, a detector detects road information through a GPS (global positioning system), checks whether a road is congested or not, simultaneously checks whether gaps and pits exist in the road or not, acquires and processes basic road data of a driving experiment based on a GPS/GPRS (global positioning system/general packet radio service) vehicle-mounted data acquisition device, and simultaneously acquires characteristic information of driving conditions such as a track, a displacement and a speed of a vehicle.

B. Constructing a quasi-steady state process typical driving condition: collecting actual road running condition data of the pure electric vehicle, extracting kinematic segments, extracting and classifying the characteristic values of the kinematic segments based on a principal component analysis and cluster analysis method, extracting representative running conditions by using correlation coefficients, constructing a comprehensive working condition conforming to the running condition characteristics of the pure electric vehicle, introducing multi-time scale kinematic parameters for describing quasi-steady-state characteristics of the running state in a kinematic segment class, and switching processes among different kinematic segments in order to meet the requirement of energy online optimization management of the running state obtained in real time in the running process of the pure electric vehicle, adopting a dimension reduction processing and fuzzy clustering method, performing secondary clustering on the segments in the segment class by using the kinematic parameters as characteristic parameters, realizing extraction and combination of the characteristic segments in the class, and completing construction of the typical running condition of the pure electric vehicle in the quasi-steady-state process, and (4) formulating off-line and on-line kinematic segment feature extraction and classification criteria, so that the running state of the pure electric vehicle presents a random continuous characteristic.

C. Energy construction and optimization management: a. introducing a hierarchical control principle to establish a pure electric vehicle energy management system, as shown in fig. 3, the control system comprises two levels of control strategies, the top level strategy is an energy management strategy, an energy optimization management model is established by adopting a Markov decision theory and is responsible for monitoring the energy flow of the whole pure electric vehicle power system, the target power of a motor is determined according to the current state of the system, the bottom level strategy is an execution control layer, power distribution and motor control are carried out according to the current state of the system to meet the power requirement of the pure electric vehicle, b, the optimal energy consumption of the pure electric vehicle in the whole comprehensive working condition interval is taken as a target under the comprehensive working condition, the comprehensive optimal power and economy of the pure electric vehicle is taken as a target under the quasi-steady-state working condition, the current state of the electric vehicle is taken as a constraint condition, a random dynamic programming optimization proposition based on the Markov decision theory is established and solved, based on a driving state transition probability matrix, an optimization proposition is integrated into a Markov decision process of a finite field, the integration process is shown in figure 4, the optimization proposition is the Markov decision process of the finite field and can be solved by a bottom-up recursion method, the optimization process has different solving time according to different discrete granularities, generally continuous online solving cannot meet the requirement of real-time control of the electric automobile, a processing mode of discrete solving online table look-up can be adopted, all possible initial values are traversed during offline solving, results are stored in a table, and when the system runs online, the current optimal control vector value is directly obtained in the mode of table look-up.

D. Executing control: in the driving process of a vehicle, a sensor collects the speed U, the acceleration a, the SOC of a battery pack and the terminal voltage U of a super capacitor in real time, firstly, the working state of a battery and the super capacitor is judged according to the SOC and the U, then, the system is judged to enter a single-drive mode or a double-drive mode or a pre-charging mode according to the obtained working state, the acceleration and the real-time speed, the output of the super capacitor is stopped if the system enters the single-drive mode, the battery pack is independently powered, the output power of the battery pack is adjusted according to the optimal output power of the battery corresponding to the working state if the system enters the double-drive mode, and the super capacitor is charged by pulse if the system enters the pre-charging mode, so that the energy receiving.

E. Estimating the SOC of the battery pack: by establishing an efficiency model of an electric vehicle power system, analyzing the change rule of the efficiency of the electric vehicle power system under three working modes of single driving of a battery pack, common driving of the battery pack and a super capacitor and pre-charging of the super capacitor by the battery pack on the basis of theoretical modeling, researching a control strategy for enabling the electric vehicle to reasonably switch the working modes along with the driving working condition and analyzing the control effect of the control strategy by taking the optimal efficiency as a target, the invention adopts a reverse modeling method to calculate the driving efficiency of the power system considering the loss of the battery pack, the super capacitor and a motor under different vehicle speeds and accelerations, an SOC and SOH estimation algorithm verification test is completed by a battery pack test system, the structure of the test system is shown in figure 5, a battery state estimation algorithm is developed by adopting a Battery Management System (BMS) hardware-in-loop simulation platform, and the established battery pack model is loaded to the BMS hardware-in-loop, the invention relates to a pure electric vehicle energy dissipation management system, which comprises a data acquisition board card, a battery pack, a battery module.