WO2019184845A1

WO2019184845A1 - Electric vehicle, and method and apparatus for calculating state of energy (soe) of power battery

Info

Publication number: WO2019184845A1
Application number: PCT/CN2019/079450
Authority: WO
Inventors: 邓林旺; 冯天宇; 林思岐; 吕纯; 杨子华
Original assignee: 比亚迪股份有限公司
Priority date: 2018-03-30
Filing date: 2019-03-25
Publication date: 2019-10-03
Also published as: CN110333448A; CN110333448B

Abstract

Provided are an electric vehicle, and a method and apparatus for calculating the state of energy (SOE) of a power battery. The method comprises the following steps: acquiring a reference curve of an open-circuit voltage (OCV) of a power battery-battery capacity Q (S101); acquiring the OCV of the power battery (S102); acquiring the current remaining available capacity of the power battery according to the OCV of the power battery and the reference curve of the OCV-Q (S103); and calculating the SOE of the power battery according to the current remaining available capacity and the OCV of the power battery (S104). According to the method for calculating the state of energy (SOE) of a power battery: a reference curve of OCV-Q is first acquired and then the OCV is acquired; then, a remaining capacity Q _remaining of a power battery is obtained according to the OCV and the reference curve of OCV-Q; and finally, the SOE is calculated according to Q _remaining and the OCV.

Description

Energy state SOE calculation method and device for electric vehicle and power battery

Cross-reference to related applications

The present application is based on the Chinese Patent Application No. 20181 029 797, the entire disclosure of which is hereby incorporated by reference.

Technical field

The present application relates to the field of electric vehicle technology, and in particular, to an energy state SOE calculation method for a power battery, an energy state SOE calculation device for a power battery, and an electric vehicle.

Background technique

Due to the dual pressures of energy and environment, electric vehicles are developing rapidly, and the power battery as the energy reserve source of electric vehicles directly determines the driving range of electric vehicles.

In order to more accurately measure the remaining power of the power battery, K. Mamadou et al. proposed the concept of a battery SOE (State of Energy), which can be used to represent the percentage of remaining energy of the power battery. In the related art, when calculating the SOE, the relationship between the battery OCV and the SOE is measured in advance under laboratory conditions, and then the BMS (Battery Management System) is used according to the current SOC of the power battery under actual vehicle conditions. (State of Charge) The OCV (Open-Circut Voltage) is checked, and then the SOE is obtained according to the OCV.

However, under the same SOC state, there is a big difference in the discharge capacity of the power battery under different operating conditions, that is, under the discharge rate allowed by the power battery, the total energy released increases with the increase of the magnification. At the same time, the current state of the power battery represented by the SOC cannot effectively correspond to the external power, and the actual battery terminal voltage variation in the actual operation cannot be accurately simulated, which makes it difficult to provide accurate prediction conditions for the driving range and the endurance time. A large estimation error. Moreover, the SOC cannot reflect the influence of the current time of the power battery and the previous charging and discharging conditions. The existing look-up table method increases the error of the SOE, which directly leads to the estimation of the driving range.

Summary of the invention

The present application aims to solve at least one of the technical problems in the above-mentioned techniques to some extent. To this end, the first object of the present application is to propose an energy state SOE calculation method for a power battery to improve the calculation accuracy of the SOE.

A second object of the present application is to provide an energy state SOE computing device for a power battery.

A third object of the present application is to propose an electric vehicle.

The embodiment of the first aspect of the present application provides a method for calculating an energy state SOE of a power battery, comprising the steps of: acquiring an open circuit voltage OCV-battery capacity Q reference curve of the power battery; acquiring an OCV of the power battery; The OCV and OCV-Q reference curves of the power battery acquire the current remaining available capacity of the power battery; the SOE of the power battery is calculated based on the current remaining available capacity of the power battery and the OCV.

According to the energy state SOE calculation method of the power battery according to the embodiment of the present application, the OCV-Q reference curve is first acquired, and the OCV is acquired, and then the remaining capacity of the power battery is obtained according to the OCV and OCV-Q reference curves, and finally the SOE is calculated according to the OCV. Therefore, the SOE is calculated directly by the capacity and the open circuit voltage OCV, which is more in line with scientific principles, and the calculated SOE is more accurate.

The second aspect of the present application provides an energy state SOE computing device for a power battery, including: a first acquiring module, configured to acquire an open circuit voltage OCV-battery capacity Q reference curve of the power battery; and a second acquiring module, An OCV for acquiring the power battery; a third acquisition module, configured to acquire a current remaining available capacity of the power battery according to an OCV and an OCV-Q reference curve of the power battery; and a calculation module, configured to use the power The current remaining available capacity of the battery and the OCV calculate the SOE of the power battery.

According to the energy state SOE calculation device of the power battery according to the embodiment of the present application, the OCV-Q reference curve is first acquired, and the OCV is acquired, and then the remaining capacity of the power battery is obtained according to the OCV and OCV-Q reference curves, and finally according to the current remaining of the power battery. The available capacity and OCV are used to calculate the SOE. Therefore, the SOE is calculated directly by the capacity and the open circuit voltage OCV, which is more in line with scientific principles, and the calculated SOE is more accurate.

DRAWINGS

1 is a flow chart of a method for calculating an energy state SOE of a power battery according to an embodiment of the present application;

2 is a schematic diagram of an OVC-Q reference curve in accordance with an embodiment of the present application;

3 is a structural block diagram of an energy state SOE computing device of a power battery according to an embodiment of the present application;

4 is a structural block diagram of an electric vehicle according to an embodiment of the present application.

detailed description

The embodiments of the present application are described in detail below, and the examples of the embodiments are illustrated in the drawings, wherein the same or similar reference numerals are used to refer to the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are intended to be illustrative, and are not to be construed as limiting.

Hereinafter, a method, an apparatus, and an electric vehicle for calculating an energy state SOE of a power battery according to an embodiment of the present application will be described with reference to the accompanying drawings.

1 is a flow chart of a method for calculating an energy state SOE of a power battery according to an embodiment of the present application. As shown in FIG. 1, the energy state SOE calculation method of the power battery includes the following steps:

S101. Obtain an open circuit voltage OCV-battery capacity Q reference curve of the power battery.

In an embodiment of the present application, the OCV-Q reference curve of the power battery can be obtained by real-time interaction between the electric vehicle and the cloud server, or from the BMS of the electric vehicle.

In one example, the OCV-Q reference curve can be pre-stored in the BMS, and the OCV-Q reference curve can be obtained directly from the BMS when needed.

In another example, the OCV-Q reference curve may be pre-stored in the cloud server, such as the OCV-Q reference curve may be stored in the cloud server by the BMS of the electric vehicle. Further, when necessary, a wireless connection can be established between the electric vehicle and the cloud server through 2G/3G/4G/5G, WIFI, etc., whereby the BMS of the electric vehicle can acquire the pre-stored OCV-Q reference curve from the cloud server.

It should be noted that, considering the aging of the power battery and other factors, in order to ensure that the OCV-Q reference curve of the power battery is closer to the current real state of the power battery, the OCV-Q reference curve of the power battery can be monitored and stored in real time through the BMS. The OCV-Q reference curve stored in the BMS and/or cloud server is updated periodically (eg, every 1 week, one month, three months, etc.).

In one specific example, the OCV-Q curve for a new battery and a 1.5 year battery is shown in Figure 2. As can be seen from Figure 2, when the open circuit voltage is the same, the capacity of the battery using 1.5 years is significantly smaller than the capacity of the new battery.

S102. Acquire an OCV of the power battery.

It can be understood that the OCV can be obtained by a pulse charge and discharge test, and the charge rate and the pulse interval time in the test can be set as needed.

For example, a discharge module and a shunt can be connected in series at both ends of the power battery, and the operation of the discharge module can be controlled by a controller. The discharge module can be set according to the set charging rate and the pulse interval time. When the discharge module is not working, the voltage U1 at both ends of the discharge module and the current I1 of the shunt are collected; when the discharge module is in operation, the voltage U2 at both ends of the discharge module and the current I2 of the shunt are collected.

Wherein, assuming that the internal resistance of the power battery is r, then OCV=U1+I1*r and OCV=U2+I2*r are established, thereby obtaining an open circuit voltage OCV=(U1*I2-U2*I1)/(I2) -I1).

S103. Acquire a current remaining available capacity of the power battery according to the OCV and OCV-Q reference curves of the power battery.

Among them, the OCV-Q reference curve of the power battery can be queried to obtain the current remaining available capacity of the power battery Q _remaining .

S104. Calculate the SOE of the power battery according to the current remaining available capacity of the power battery and the OCV.

It can be understood that the current remaining available energy E _{remaining of the} power battery is calculated according to the current remaining available capacity Q _remaining and OCV of the power battery. The nominal capacity of the power battery is obtained, and the nominal energy E _{N of the} power battery is calculated based on the nominal capacity Q _N and OCV of the power battery. The SOE is calculated based on the current remaining available energy E _{remaining of the} power battery and the nominal capacity E _N . The calculation formula is as follows (1):

According to the energy state SOE calculation method of the power battery according to the embodiment of the present application, the OCV-Q reference curve is first acquired, and the OCV is acquired, and then the remaining capacity of the power battery Q _{remaining is} obtained according to the OCV and OCV-Q reference curves, and finally according to Q _remaining and The OCV calculates the SOE. Therefore, the SOE is calculated directly by the capacity and the open circuit voltage OCV, which is more in line with scientific principles, and the calculated SOE is more accurate. In addition, considering the aging of the battery and other factors, periodically updating the OCV-Q reference curve can make the calculated SOE more accurate and closer to the real state of the power battery, which in turn helps to more accurately estimate the subsequent vehicle continuation. Mileage or battery life.

3 is a block diagram showing the structure of an energy state SOE computing device for a power battery according to an embodiment of the present application. As shown in FIG. 3, the energy state SOE computing device 100 of the power battery includes a first acquisition module 10, a second acquisition module 20, a third acquisition module 30, and a calculation module 40.

The first obtaining module 10 is configured to obtain an open circuit voltage OCV-battery capacity Q reference curve of the power battery.

In an embodiment of the present application, the OCV-Q reference curve of the power battery may be obtained by real-time interaction between the electric vehicle and the cloud server, or may be obtained from the BMS of the electric vehicle.

It can be understood that, in one example, the OCV-Q reference curve can be pre-stored in the BMS, so that the first acquisition module 10 can directly acquire the OCV-Q reference curve from the BMS when needed.

In another example, the BMS of the electric vehicle may be pre-stored in the cloud server, such as the OCV-Q reference curve may be stored in the cloud server by the BMS of the electric vehicle. Further, when necessary, a wireless connection can be established between the electric vehicle and the cloud server through 2G/3G/4G/5G, WIFI, etc., whereby the first acquisition module 10 can acquire the pre-stored OCV-Q reference curve from the cloud server.

The second acquisition module 20 is configured to acquire an OCV of the power battery.

Among them, OCV can be obtained by pulse charge and discharge test, and the charge rate and pulse interval time in the test can be set as needed.

The third acquisition module 30 is configured to obtain the current remaining available capacity of the power battery according to the OCV and OCV-Q reference curves of the power battery.

It can be understood that the third obtaining module 30 can query the OCV-Q reference curve according to the OCV of the power battery to obtain the current remaining available capacity Q _{remaining of the} power battery.

The calculation module 40 is configured to calculate the SOE of the power battery based on the current remaining available capacity of the power battery and the OCV.

The calculation module 40 calculates the current remaining available energy E _{remaining of the} power battery according to the current remaining available capacity Q _remaining and OCV of the power battery. The nominal capacity of the power battery is obtained, and the nominal energy E _{N of the} power battery is calculated based on the nominal capacity Q _N and OCV of the power battery. The SOE is calculated based on the current remaining available energy E _{remaining of the} power battery and the nominal capacity E _N . The calculation formula is as follows (1):

According to the energy state SOE calculation device of the power battery according to the embodiment of the present application, the OCV-Q reference curve is first acquired, and the OCV is acquired, and then the remaining capacity of the power battery Q _{remaining is} obtained according to the OCV and OCV-Q reference curves, and finally according to Q _remaining and The OCV calculates the SOE. Therefore, the SOE is calculated directly by the capacity and the open circuit voltage OCV, which is more in line with scientific principles, and the calculated SOE is more accurate. In addition, considering the aging of the battery and other factors, periodically updating the OCV-Q reference curve can make the calculated SOE more accurate and closer to the real state of the power battery, which in turn helps to more accurately estimate the subsequent vehicle continuation. Mileage or battery life.

4 is a structural block diagram of an electric vehicle according to an embodiment of the present application. As shown in FIG. 4, the electric vehicle 1000 includes the energy state SOE calculating device 100 of the power battery of the above embodiment.

According to the electric vehicle of the embodiment of the present application, the energy state SOE calculating device of the power battery of the above embodiment directly calculates the SOE by the capacity and the open circuit voltage OCV, which is more in line with scientific principles, and the calculated SOE is more accurate. In addition, considering the aging of the battery and other factors, periodically updating the OCV-Q reference curve can make the calculated SOE more accurate and closer to the real state of the power battery, which in turn helps to more accurately estimate the subsequent vehicle continuation. Mileage or battery life.

It should be noted that other configurations and functions of the electric vehicle of the embodiment of the present application are known to those skilled in the art, and redundancy is not described herein.

In the description of the present specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means a specific feature described in connection with the embodiment or example. A structure, material or feature is included in at least one embodiment or example of the application. In the present specification, the schematic representation of the above terms is not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, various embodiments or examples described in the specification and features of the various embodiments or examples may be combined and combined.

Moreover, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, features defining "first" or "second" may include at least one of the features, either explicitly or implicitly. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless specifically defined otherwise.

Any process or method description in the flowcharts or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a custom logic function or process. And the scope of the preferred embodiments of the present application includes additional implementations, in which the functions may be performed in a substantially simultaneous manner or in the reverse order depending on the functions involved, in accordance with the illustrated or discussed order. It will be understood by those skilled in the art to which the embodiments of the present application pertain.

The logic and/or steps represented in the flowchart or otherwise described herein, for example, may be considered as an ordered list of executable instructions for implementing logical functions, and may be embodied in any computer readable medium, Used in conjunction with, or in conjunction with, an instruction execution system, apparatus, or device (eg, a computer-based system, a system including a processor, or other system that can fetch instructions and execute instructions from an instruction execution system, apparatus, or device) Or use with equipment. For the purposes of this specification, a "computer-readable medium" can be any apparatus that can contain, store, communicate, propagate, or transport a program for use in an instruction execution system, apparatus, or device, or in conjunction with the instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer readable media include the following: electrical connections (electronic devices) having one or more wires, portable computer disk cartridges (magnetic devices), random access memory (RAM), Read only memory (ROM), erasable editable read only memory (EPROM or flash memory), fiber optic devices, and portable compact disk read only memory (CDROM). In addition, the computer readable medium may even be a paper or other suitable medium on which the program can be printed, as it may be optically scanned, for example by paper or other medium, followed by editing, interpretation or, if appropriate, other suitable The method is processed to obtain the program electronically and then stored in computer memory.

It should be understood that portions of the application can be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware and in another embodiment, it can be implemented by any one or combination of the following techniques well known in the art: discrete with logic gates for implementing logic functions on data signals Logic circuits, application specific integrated circuits with suitable combinational logic gates, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), and the like.

Claims

A method for calculating an energy state SOE of a power battery, comprising the steps of:

Obtaining an open circuit voltage OCV-battery capacity Q reference curve of the power battery;

Obtaining an OCV of the power battery;

Obtaining a current remaining available capacity of the power battery according to an OCV and an OCV-Q reference curve of the power battery;

The SOE of the power battery is calculated based on the current remaining available capacity of the power battery and the OCV.
The energy state SOE calculation method of the power battery according to claim 1, wherein the calculating the SOE of the power battery according to the current remaining available capacity of the power battery and the OCV specifically includes:

Calculating the power based on the current battery power remaining available capacity of the battery and the OCV Q remaining current remaining available energy E remaining;

Obtaining the nominal capacity of the battery power Q N, Q N and computing capacity of the nominal battery power according to the nominal energy E N;

The SOE is calculated based on the current remaining available energy E remaining of the power battery and the nominal energy E N .
The energy state SOE calculation method for a power battery according to claim 2 or 3, wherein the SOE is calculated by the following formula:

Wherein, the Q N is a nominal capacity of the power battery.
The energy state SOE calculation method for a power battery according to any one of claims 1 to 3, wherein the OCV-Q reference curve of the power battery is obtained by real-time interaction between the electric vehicle and the cloud server.
An energy state SOE computing device for a power battery, comprising:

a first obtaining module, configured to acquire an open circuit voltage OCV-battery capacity Q reference curve of the power battery;

a second obtaining module, configured to acquire an OCV of the power battery;

a third obtaining module, configured to acquire, according to an OCV and an OCV-Q reference curve of the power battery, a current remaining available capacity of the power battery;

And a calculation module, configured to calculate an SOE of the power battery according to the current remaining available capacity of the power battery and the OCV.
The energy state SOE computing device of a power battery according to claim 5, wherein the calculation module is specifically configured to:

Calculating the power based on the current battery power remaining available capacity of the battery and the OCV Q remaining current remaining available energy E remaining;

Acquiring the power battery nominal capacity Q N, and the capacity Q N calculating the battery nominal energy E N according to the nominal;

The SOE is calculated based on the current remaining available energy E remaining of the power battery and the nominal energy E N .
The energy state SOE calculation method for a power battery according to claim 5 or 6, wherein the calculation module calculates the SOE by using the following formula:

Wherein, the Q N is a nominal capacity of the power battery.
The energy state SOE computing device for a power battery according to any one of claims 5-7, wherein the OCV-Q reference curve of the power battery is obtained by real-time interaction between the electric vehicle and the cloud server.
An electric vehicle characterized by comprising an energy state SOE computing device for a power battery according to any one of claims 5-8.