CN109606200B

CN109606200B - New energy automobile battery management system

Info

Publication number: CN109606200B
Application number: CN201811552728.XA
Authority: CN
Inventors: 朱全; 张磊
Original assignee: JIANGSU KEDA CAR INDUSTRY CO LTD
Current assignee: JIANGSU KEDA CAR INDUSTRY CO LTD
Priority date: 2018-12-19
Filing date: 2018-12-19
Publication date: 2020-12-22
Anticipated expiration: 2038-12-19
Also published as: CN109606200A

Abstract

The invention relates to the technical field of battery management systems, in particular to a new energy automobile battery management system which comprises a battery management unit and a battery control unit, wherein the battery management unit is used for acquiring battery brick information and uploading the information to a battery control unit communicated with the battery management unit, and the battery control unit receives the battery brick information uploaded by the battery management unit communicated with the battery control unit and performs SOC estimation and balance control operation. According to the invention, the equivalent parameters of the battery are estimated through a real-time online estimation method, so that the SOC state of the battery pack is accurately estimated. The calibration work of the battery is simplified through real-time online estimation. Making accurate control of the state of the battery pack less consistent practical. The real-time online estimation can keep higher precision and stronger error correction capability no matter whether the battery is a new battery or an aged battery.

Description

New energy automobile battery management system

Technical Field

The invention relates to the technical field of battery management systems, in particular to a new energy automobile battery management system.

Background

The key point of the traditional fuel oil automobile is that the traditional fuel oil automobile is not commonly called three major parts: the engine, the chassis and the gearbox are also commonly called as three parts on the new energy electric automobile: the battery, the motor and the electric control are still the newer industries in the world, so that the starting difference of enterprises in various countries is not great, and the enterprises in China have higher conditions than foreign enterprises on the multi-purpose power driving tool invented by the automobile in 1886. The new energy electric automobile is controlled by electricity in three major parts, namely a battery management system BMS is generally called in the industry.

The biggest difference between the new energy electric automobile and the traditional fuel oil automobile is that a power battery is used as power for driving, and is used as an important link for connecting a battery pack, a whole automobile system and a motor, the importance of a battery management system BMS is self-evident, and many new energy automobile enterprises at home and abroad consider the battery management system as the most core technology of enterprises.

The main working principle of the BMS can be briefly summarized as that a data acquisition circuit first acquires battery state information data, then an Electronic Control Unit (ECU) processes and analyzes the data, and then sends control instructions to related functional modules in the system according to the analysis results and transmits information to the outside. Based on the above principles, the university of toledo, usa, proposes a typical BMS infrastructure. This typical system simply divides the BMS into two major parts, 1 ECU and 1 Equalizer (EQU) that equalizes the charge levels between the cells. The task of the ECU mainly comprises 4 functions of data acquisition, data processing, data transmission and control. The ECU also controls battery maintenance equipment such as an equalizer, an in-vehicle charger, and the like.

The BMS system developed by the korean Ajou university and the advanced engineering research institute adds a thermal management system, a safety device, a charging system, and a communication link with a PC. In addition, the communication link with the motor controller is increased, and energy brake feedback and maximum power control are realized.

A centralized BMS architecture adopted by electric vehicles developed by the university of hunan (EV 23). The BMS system has the greatest advantage that the reliability of data acquisition and the safety of the system are improved by adopting the voltage isolating switch matrix. A plurality of isolated digital and analog signal input and output channels in the system can be flexibly used according to requirements, and the anti-interference capability of the system is effectively enhanced.

At present, the research on the BMS based on the intelligent battery module (SBM) is being developed abroad, that is, 1 microcontroller is installed in 1 battery module and related circuits are integrated, and then the battery modules are packaged into a whole, and a plurality of intelligent battery modules are connected with 1 main control module and are added with other auxiliary devices to form 1 management system based on the intelligent battery. The BMS successfully realizes the functions of monitoring the state of each battery module, balancing the electric quantity of the battery in the module, protecting the battery and the like. This is the structure adopted by military electric vehicle BMS developed by Micron corporation of usa.

In combination with research works at home and abroad, the currently designed BMS for electric vehicles generally include functional components such as data acquisition, estimation of a remaining capacity (SOC), electrical control (charge and discharge control, equalization control, and the like), thermal management, safety management, and data communication.

In a BMS, the collected data is the basis for reasonably efficient management and control of the battery. Therefore, the accuracy of the data, sampling frequency, and data filtering are very important. In view of the dynamic variation characteristics of voltage, current and temperature, the sampling frequency should be usually not lower than 1/s. The lithium ion battery has high safety requirement and is sensitive to voltage, so the voltage of each single battery must be collected and the temperature of each battery is monitored. The nickel-metal hydride battery and the lead-acid battery have the requirements on the collection accuracy of voltage and temperature which are not as high as those of the lithium ion battery, and sometimes the voltage and the temperature are collected in pairs or groups in order to simplify the structure of the BMS.

Determination of the remaining battery capacity (SOC) is an important and difficult point in the BMS. Due to the high nonlinearity of the battery of the electric automobile in the using process, the accurate estimation of the SOC has great difficulty. The traditional SOC basic estimation method comprises an open-circuit voltage method, an internal resistance method, an ampere-hour method and the like. In recent years, many new algorithms for the battery SOC have been developed, such as a fuzzy logic algorithm model, an adaptive neural fuzzy inference model, a kalman filter estimation model algorithm, a linear model method, an impedance spectroscopy method, and the like.

The open-circuit voltage method is suitable for testing the SOC of the battery in a stable state, and is not suitable for being used independently in the running process of the electric automobile. The open circuit voltage method is often used as a complement to other algorithms. The internal resistance method is to predict the SOC based on the relation between the internal resistance of the battery and the SOC. However, the internal resistance of the battery is influenced by various factors, the measurement result is easily interfered, and the reliability is not high. In addition, the method is complex and large in calculation amount, so that the method is difficult in practical application. The ampere-hour method records the energy output from the storage battery or the energy input into the storage battery by a current integration method, and then can calculate the SOC of the storage battery according to the initial SOC state of charging and discharging. The method is most direct and obvious, is simple and feasible, has higher precision in a short time, and has larger accumulated error when working for a long time.

In practical applications, the ampere-hour method is the most commonly used method at present, and is often used in combination with other methods, such as ampere-hour internal resistance method, ampere-hour-Peukert equation method, ampere-hour-open circuit voltage method. The combined algorithms are generally higher in precision than the method of using ampere-hour only, and various intelligent algorithms and novel algorithms are not mature yet, and some complex algorithms are difficult to realize on a single chip microcomputer system, so that the algorithms are not common in practical application, but the combined algorithms are the direction of future development.

In order to estimate the SOC more accurately, various factors such as temperature compensation, self-discharge and aging of the battery also need to be considered in the algorithm. For example, in the estimation of the SOC of a nickel-metal hydride battery by researchers at Ajou university and advanced engineering research institute in korea, the actual available capacity of the battery (including temperature considerations), the self-discharge rate and the effect of battery aging on the capacity are considered, and an SOC calculation formula is proposed as follows:

SOC (%) = 100% x (rated capacity + capacity compensation factor + self-discharge effect + aging effect-discharge amount + charge amount)/rated capacity.

The SOC estimation accuracy is within +/-3%.

Researchers such as Jossen a in germany believe that electrical control requires functions such as controlling the charging process, including equalizing the charge, and limiting the discharge current based on SOC, state of health (SOH) of the battery, and temperature. In the electrical control, an algorithm logic for controlling charging and discharging needs to be set in combination with the battery technology and the battery type used, and the algorithm logic is used as a standard for controlling charging and discharging.

In the BMS, the equalizing charge is a very critical link. The power battery is generally formed by connecting a plurality of single batteries with larger capacity in series. However, due to the fact that inconsistency exists among the single batteries, the using level of the battery pack can be reduced, the performance of the electric automobile is seriously affected, and the safety of the electric automobile is endangered. For example, in EV23 developed at the university of hunan, it was found that when the equalizing charge is not used, the voltage difference between the nickel-metal hydride battery packs of 1 pack of 10 unit batteries is about 2V at maximum after the batteries are charged and discharged a plurality of times.

There are various schemes for equalizing charge, and the scheme should be selected in consideration of circuit complexity and equalization efficiency. The university of toledo, usa employs a centralized, non-dissipative type of selective boost equalizer in its BMS. The scheme is to perform equalizing charge on the selected single batteries by controlling the switching of the relay network, and hardware equipment is simpler than independent equalization but has relatively lower efficiency. A battery pack equalizing charge protection system scheme is adopted on an electric bus BFC6100EV developed by Beijing university of science and engineering to realize the comprehensive application of equalizing charge and battery protection.

The safety problem of the battery, especially the lithium ion battery, can catch fire or even explode when overcharged, so the safety problem of the battery is the current problem which is faced and must be solved by various automobile companies and scientific research institutions at home and abroad, and the safety problem directly influences whether the electric automobile can be popularized and applied. The BMS, which mainly focuses on protection of the battery in terms of safety and prevention of leakage of high voltage and high current, must perform the functions of overvoltage and overcurrent control, overdischarge control, prevention of excessive temperature, and shutdown of the battery in the event of a collision.

These functions may be accomplished in conjunction with an electrical control, thermal management system. Many systems are specialized in adding battery protection circuits and battery protection chips. The most important thing of the safety management system is to accurately grasp the status information of each battery in time, and to send out alarm signals or disconnect the circuit in time when abnormal conditions occur, so as to prevent accidents.

The battery has different working performances at different temperatures, for example, the optimal working temperature of a lead-acid battery, a lithium ion battery and a nickel-metal hydride battery is 25-40 ℃. 9 the change of the temperature can change the SOC, the open-circuit voltage, the internal resistance and the available energy of the battery and even affect the service life of the battery. The difference in temperature is also one of the causes of the problem of cell equalization. Ahmad a. Pesaran of the national laboratory of renewable energy in the united states that the main task of the thermal management system is to operate the battery in a suitable temperature range and to reduce the temperature differences between the individual battery modules. The temperature of the battery can be controlled by using the vehicle-mounted air conditioner, which is also a commonly used temperature control method for the electric automobile.

Data communication is one of important components of the BMS. In the BMS, the data communication method mainly employs a CAN bus communication method at present. In BMS developed by cooperation of building university and Qinghua university, an internal CAN network is used among modules in the BMS, and another CAN communication interface in the communication and display module is connected into the CAN communication network of the whole automobile. In a test developed at the university of congratulation for BMS beyond fuel cell electric vehicles, the internal modules communicate using the LIN bus and the communication with the entire vehicle using the CAN bus.

When the intelligent battery module is adopted, a wireless communication mode can be selected to be used, or the intelligent battery module can be communicated with the main controller in a power carrier wave mode. The 2 communication modes CAN reduce wiring of the BMS and complexity of circuits in the electric automobile, but the reliability and the anti-interference capability of the communication modes are inferior to those of the CAN bus.

In new energy transportation equipment, especially in an Electric Vehicle (EV) system, in order to meet requirements of endurance mileage and Vehicle speed, a battery pack needs to be used in a series-parallel combination manner, but the reliability and the service life of the battery pack are greatly reduced due to the series-parallel combination use of a large number of batteries.

Disclosure of Invention

The invention aims to provide a new energy automobile battery management system to solve the problems in the background technology. The new energy automobile battery management system accurately estimates the SOC state of the battery pack, and accurate estimation of the state of charge of the battery is achieved.

In order to achieve the purpose, the invention provides the following technical scheme:

the utility model provides a new energy automobile battery management system, includes battery management unit and battery control unit, the battery management unit is used for gathering battery brick information to reach the battery control unit rather than communication with the information upload, battery control unit receives the battery brick information of uploading rather than the battery management unit of communication connection, and carries out SOC estimation and balanced control operation.

Furthermore, the battery control unit is in communication connection with the charger system.

Further, the vehicle-mounted electric drive system is further included, and the battery control unit is in communication connection with the vehicle-mounted electric drive system.

Furthermore, the battery management unit is a plurality of, and it includes control chip, a plurality of collection chip, and this collection chip is connected with control chip SPI bus, the battery control unit is one, and it adopts master control chip MPC5744P and system chip MC 33908.

Furthermore, the battery management unit and the battery control unit are connected through a CAN bus.

Furthermore, the battery control unit is connected with the charger system through a CAN bus.

Furthermore, the battery control unit is connected with the vehicle-mounted electric drive system through a CAN bus.

Further, it is characterized in that: the battery control unit is connected with a touch screen through an RS485 bus.

Compared with the prior art, the invention has the beneficial effects that:

the equivalent parameters of the battery are estimated through a real-time online estimation method, so that the SOC state of the battery pack is accurately estimated. The calibration work of the battery is simplified through real-time online estimation. Making accurate control of the state of the battery pack less consistent practical. The real-time online estimation can keep higher precision and stronger error correction capability no matter whether the battery is a new battery or an aged battery.

Drawings

Fig. 1 is a schematic diagram of a new energy vehicle battery management 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.

In the description of the present invention, it should be noted that the terms "upper/lower end", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be configured in a specific orientation, and operate, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed/sleeved," "connected," and the like are to be construed broadly, e.g., "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Referring to fig. 1, the present invention provides a technical solution:

a Battery Management System (BMS) of a new energy automobile is mainly formed by combining a Battery Management Unit (BMU) and a Battery Control Unit (BCU). The BMS adopts a distributed master-slave structure and consists of a plurality of BMUs and a single BCU, wherein the BCU is responsible for communicating with an external driving system and a master control system to acquire instructions, upload and display battery pack information, and meanwhile, the BCU receives battery brick information uploaded by each single BMU to perform SOC estimation and balance control operation.

In order to solve the problems of Battery state observation and maximum Battery pack utilization, a Battery Management System (BMS) is required to monitor and protect the Battery.

The BMS is a key component for guaranteeing and expanding functions and performances of the battery pack as a unique provider of information of the power battery of the whole vehicle and protecting and controlling the battery, so that the good output performance of the power battery pack is ensured, the cycle life of the power battery pack is prolonged, and an effective state monitoring, indirect control, management and alarm mechanism is required to be provided, so that a reference basis is provided for the safety of the whole vehicle.

The invention comprises the following steps:

1. adopting a latest hardware architecture meeting ISO26262 specification of Emizpu, and adding a main control chip MPC5744P and a system chip MC 33908;

2. by adopting the AUTOSAR software architecture, the bottom layer software and the application layer software can be synchronously and independently developed, the development period is shortened, the software portability is improved, and a foundation is laid for completing the ISO26262 function safety certification;

3. the equivalent parameters of the battery are estimated through a real-time online estimation method, so that the SOC state of the battery pack is accurately estimated. The calibration work of the battery is simplified through real-time online estimation. Making accurate control of the state of the battery pack less consistent practical. The real-time online estimation can keep higher precision and stronger error correction capability no matter whether the battery is a new battery or an aged battery.

The invention comprises the following steps:

1. and updating the state estimation and the observation estimation based on the iterative minimum mean square error estimation, thereby realizing the accurate estimation of the state of charge of the battery.

2. A self-adaptive Sigma Kalman particle filter battery residual life prediction method based on a data-driven fusion model.

3. Based on a battery management chip proposed by TI company, a controllable resistance balancing scheme is designed, and the duty ratio of a control signal is output by detecting the voltage of each battery, so that the single battery is independently adjusted.

The invention comprises the following steps:

1. realizing accurate estimation of the SOC of the battery;

2. estimating the health state, and estimating the maximum allowable instantaneous (5s/30s) and continuous charging and discharging power;

3. the high-efficiency balance management technology and an advanced heat dissipation mechanism are realized, and the maximum passive balance current of 200mA can be supported;

4. the high-precision measurement technology is realized, and the total pressure precision of the total flow reaches 1% FSR.

The invention has the following functions:

1. and (3) realizing battery safety management: the system has reliable overcharge/overdischarge protection, overcurrent/overtemperature/low-temperature protection and multi-stage fault diagnosis protection;

2. and (3) realizing high-voltage safety management: the method has the advantages of high-voltage relay adhesion detection, high-interference-resistance high-voltage interlocking detection and advanced high-voltage insulation monitoring;

3. the function of diagnosing the broken line of the voltage and temperature acquisition line is realized;

4. and safety mechanisms such as loop overcurrent and short-circuit protection of the battery voltage acquisition module are realized.

The invention comprises the following steps:

1. the system can normally work at a higher temperature range of-40 ℃ to 85 ℃;

2. the wide temperature monitoring range is realized, and the monitoring range reaches-40 to 125 ℃.

The invention comprises the following steps:

1. support the charging national standards GB/T20234-;

2. the requirements of product function safety life cycle management in ISO26262 international safety standard are supported;

3. support CCP calibration protocol, UDS, OBD-ii diagnostic protocol.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The new energy automobile battery management system is characterized by comprising a battery management unit and a battery control unit, wherein the battery management unit is used for acquiring battery brick information and uploading the information to a battery control unit communicated with the battery management unit;

the battery management units are multiple and comprise a control chip and multiple acquisition chips, the acquisition chips are connected with an SPI bus of the control chip, and the battery control units are one and adopt a master control chip MPC5744P and a system chip MC 33908;

updating the state estimation and the observation estimation based on the iterative minimum mean square error estimation, thereby realizing the accurate estimation of the state of charge of the battery; a self-adaptive Sigma Kalman particle filter battery residual life prediction method based on a data-driven fusion model; based on a battery management chip proposed by TI company, a controllable resistance balancing scheme is designed, and the duty ratio of a control signal is output by detecting the voltage of each battery, so that the single battery is independently adjusted.

2. The new energy automobile battery management system according to claim 1, characterized in that: the battery control unit is in communication connection with the charger system.

3. The new energy automobile battery management system according to claim 1, characterized in that: the vehicle-mounted electric drive system is further included, and the battery control unit is in communication connection with the vehicle-mounted electric drive system.

4. The new energy automobile battery management system according to claim 1, characterized in that: the battery management unit is connected with the battery control unit through a CAN bus.

5. The new energy automobile battery management system according to claim 2, characterized in that: the battery control unit is connected with the charger system through a CAN bus.

6. The new energy automobile battery management system according to claim 3, characterized in that: and the battery control unit is connected with the vehicle-mounted electric drive system through a CAN bus.

7. The new energy automobile battery management system according to any one of claims 1 to 6, characterized in that: the battery control unit is connected with a touch screen through an RS485 bus.