Electric vehicle battery management system research

Electric vehicle battery management system research

This paper introduces the characteristics of the lithium-ion battery, reviewing the development history of electric vehicle battery management system, briefly introduces the requirements and functionality, technical characteristics of battery management system, and looks forward to the development of electric vehicle battery management system. The emergence of electric vehicles is driven by global warming, environmental pollution and energy crisis..

In 2015, the global electric vehicle production and shipments exceeded 500,000 units, including more than 370,000 vehicles.. Electric vehicles must have electrical energy storage devices, current lithium-ion batteries are the preferred and mainstream of power lithium batteries.

The lithium-ion battery exists in the series in series, excessive, overlapping, overcurrent, temperature is too low, etc., which will cause the rapid damage of lithium-ion batteries, so the battery management system is administered. 1, lithium-ion battery lithium ion battery refers to a battery made from four important materials and housings of the positive electrode, an negative electrode, a diaphragm, an electrolyte?.

The positive and negative electrode materials must be able to be reversible, and the separator must be a lithium ion conducting and electronically insulating, the electrolyte must be a lithium ion solution.. Usually, a transition element is redox reaction in a transition element, and the metal lithium and carbon negative electrode are oxidative reactions in metal lithium.

. The charge and discharge process, the lithium ion is transferred back and forth between the internal and negative poles of the battery, and the battery moves in the outer circuit..

Some people have impeded this lithium ion transfer process into a rocking chair, and the lithium-ion battery is called a rocker battery.. Figure 1 Operation of lithium ion batteries illustrate lithium ion battery positive electrode material generally uses a pithiform lithium transition metal oxide, such as Ni, Co, and Mn is lithium oxide.

The negative electrode material is selected to select the potential as close as possible to the metallium lithium compound compound, such as various carbon materials, SNO, SnO2, silicon alloy, etc.. The electrolytic solution generally uses the solution of LiPF6, the solute is organic, commonly used with ethylene carbonate (EC), propylene carbonate (PC), and low density di-vinyl carbonate (DEC), etc.

; the separator is important to be made of olefin polymer Porous composite film; housing material has steel, aluminum, plastic, aluminum plastic film, etc.. Lithium-ion batteries are as follows: Figure 2 Typical Structure of Square Battery Lithium Ion Battery Typical parameters include: capacity, internal resistance, voltage; lithium ion battery characteristics Parameters include: circulating life, discharge platform, self-discharge ratio, temperature performance, Storage performance, etc.

. Lithium-ion battery safety test is: overcharge, short circuit, acupuncture, drop, immersion, low pressure, vibration, etc..

The lithium-ion battery is more proud, and its charge and discharge is a multivariate, non-linear complex electrochemical process, if you don’t meet the conditions of charge and discharge, it is easy to have a rapid life, performance reduction, fire, explosion, etc., because lithium Ion battery is sensitive to temperature, voltage, current, etc..

2. Early battery management system of battery management system has: Badicheq and Badicoach system designed in 1991 in 1991, the battery management system used by American General Automotive EV1, US ACPROPULSION company developed high-performance battery management system. The earliest importance in China is some research work to rely on its own technology advantages.

Some large automobiles and battery producers have conducted some research work. Tsinghua University is equipped with EV-6568 light electric passenger cars. Tongji University and Beijing Xingheng cooperation has been developed.

Lithium-ion battery management system, Chunlan Research Institute developed HEV-BMS system, Beijing Institute of Technology and North Jiaotong University, etc., the national 863 planned electric vehicle major special child, and also developed a characteristic battery management system. With the start of the electric car market, many commercial products have obtained large quantities.

. 3. Battery management system research content first, to study battery management system, generally study single-chip microcomputer as the core, in-vehicle network is distributed system.

Then study the sensing because the parameters of the battery are detected. General detection voltage, current, temperature. Data and control of the transmission requires a network to implement, generally use CAN networks.

Executive agencies, achieved by display, relays, fans, pumps, motors, etc.. Figure 3 Hardware system schematic diagram of the battery management system has a management implementation system, and the running system to be managed.

The management of the battery is divided into three processes of discharge, charging and standing.. Stand involving temperature, safe management.

Charging involves the configuration of the charging parameters, the monitoring of the charging process, the temperature, voltage and current protection of the charging process. The discharge process involves the management of output power, the management of electricity planning, the use of process voltage, current, temperature management. Charging and discharge standing will refer to the same parameters, which is the remaining electricity capacity, also called the PT, StateOfcharge.

The discharge process of the lithium-ion battery is a very complex electrochemical process. It is affected by many factors. The estimation of the remaining electricity is very difficult, and the difficulty comes from the following aspects: First, the battery is not fixed, exactly the same experience and state Under the parameter, the battery capacity is not fixed; the second is that the battery is aging cannot be determined.

The aging of the battery cannot be accurately calibrated. The degree of dispersion within the battery pack cannot be accurately calibrated; third is the randomness of the use process. Document [1] Introduce the estimation method of various SOCs.

During the use of the lithium-ion battery, even if the performance of the single cell is superior, there is inconsistency between the monomers, and the battery pack will change the characteristics during use, and the battery pack is currently using the unit. There is a dispersibility, there is no effective solution, so we must solve the balance problem in each single-cell lithium-ion battery in the battery pack..

At present, general equilibrium methods have equilibrium, charging equalization and energy transfer balance. The most typical use is the energy consumption balance. The method utilizes the heat-resistance bypass division, the principle is shown below: The principle of the energy consumption equalization of Figure 4 shows that the charging equalization is the end of charging, using a small battery alone Charger is full of electricity.

Energy transfer balance due to the difficulties of SOC measurement, although there are many research and development, have not yet entered practical products. Of course, the battery management system is still not enough. The temperature will rise during the use of the battery, and the temperature is too high for the lithium-ion battery.

This is an undesirable situation.. Therefore, the initial battery management system has added a function of heat generation management.

. Later, it was found that the battery temperature after the low temperature environment was too low, and the heating management was carried out..

Further expansion of the range of battery use, the battery security problem is increased, so there is a problem with safety management.. The initial safety management is monitoring, BMS sends the battery data to the monitoring center, and the monitoring center determines security hidden dangers according to data.

. Further development to the security warning for BMS itself. The battery is always maintained, replacing the monomer, balancing, etc.

during use, these work should be diagnosed, if BMS has been doing a diagnosis before you want, the data is ready, then the corresponding work will become simple, The battery management system has added a function of fault diagnosis and submission [2]. With the increase of retired batteries, the ladder of the battery has shown a problem with the problem [3], and the ladder uses the battery to carry out a lot of research, BMS assumes the management function of the communication..

The advancement of battery development also rely on problems found during battery use, and relying on the choice of actual use process, the battery management system has added the function of battery technology [4]. 4, battery management system development prospective measurement is the basis of battery management, increasingly accurate, and technologically and higher resolution technology is applied to battery management system..

The research of SOC estimation is also developed from one color time division to other methods such as Joule points.. More and more battery management functions are worthy of concern, the rise of multi-stage battery management systems.

From the master-slave structure, develop to each independent replacement unit can have a complete battery management system function. In addition to the battery system, the vehicle battery management, and the background server battery management procedures are also rising. In addition, it is worth paying that the battery management system is no longer passively to protect the battery, but optimizes the use and use environments.

. Temperature management is an optimization environment, parameter deduction is optimized. With the development of the industry, you can look forward to more and better battery management technology and product emergence.

. [1] Ouyang Jian, Li Di, Liu Juncheng.Research Summary of Estimation Method of Power Lithium Battery Power Electric Machine for Electric Vehicles [J] .

CHV Technology, 2016,45 (1): 52-56. [2] Zhao Hongtao, Han Wen Analysis of Pneumatic Automotive Battery Management System [J]. Shandong Industrial Technology, 2016,3 (7): 61-62.

[3] Liu Daocan, Fan Longong. Performance Test and Analysis of Power Lithium Battery of Eneven Electric Vehicle [J] Power Technology, 2016, 3: 532-535 [4] Summary of the modeling and application of dynamic lithium battery [J]. Power Technology, 2016,3: 736-739.

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