Research on battery management system -Lithium - Ion Battery Equipment

Research on Electric Vehicle Battery Management System -Lithium - Ion Battery Equipment

This paper introduces the characteristics of lithium-ion batteries, summarizes the development history of electric vehicle battery management systems, briefly introduces the requirements, functions, and technical characteristics of battery management systems, and makes an outlook for the development of electric vehicle battery management systems.

The emergence of electric vehicles is driven by global warming, environmental pollution and energy crisis. In 2015, the global production and shipment of electric vehicles exceeded 500,000, of which my country exceeded 370,000.

Electric vehicles must have an electrical energy storage device. At present, lithium-ion batteries are the first choice and mainstream of power lithium batteries.

When lithium-ion batteries are used in series, there are problems such as overcharge, over-discharge, over-current, and high and low temperature, which will cause rapid damage to lithium-ion batteries, so they need to be managed by a battery management system.

1. Lithium-ion battery

Lithium-ion battery refers to a battery made of four important materials and shells: positive electrode, negative electrode, separator, and electrolyte. The positive and negative electrode materials must be able to reversibly intercalate and deintercalate lithium ions, the separator must be conductive with lithium ions and electronically insulated, and the electrolyte must be a lithium ion solution.

Usually, a transition element in the positive electrode material undergoes a redox reaction, while the metal lithium and carbon negative electrodes are a redox reaction of metal lithium. During the charging and discharging process, lithium ions are transferred back and forth between the positive and negative electrodes inside the battery, and the battery moves in the external circuit. Some people vividly call this lithium-ion transfer process a rocking chair, and the lithium-ion battery is called a rocking-chair battery.(Lithium - Ion Battery Equipment)

Lithium-ion battery cathode materials generally use lithium intercalation transition metal oxides, such as Ni, Co, Mn intercalated lithium oxides. The negative electrode material should choose a lithium intercalation compound whose potential is as close as possible to metallic lithium, such as various carbon materials, SnO, SnO2, silicon alloy, etc.

The electrolyte commonly used is reported LipF6 solution, the solute is organic, commonly used are ethylene carbonate (EC), propylene carbonate (pC) and low-density diethylene carbonate (DEC); the diaphragm is mainly made of olefin polymers Porous composite membrane; shell materials include steel, aluminum, plastic, aluminum-plastic film, etc.

Lithium-ion batteries are relatively delicate, and their charge and discharge is a multi-variable, nonlinear and complex electrochemical process. If they cannot meet the requirements of their charge and discharge conditions, it is prone to rapid decline in lifespan, performance degradation, fire, explosion and other events. Ion batteries are sensitive to temperature, voltage, current, etc.

2. Development of battery management system

The early battery management systems include: the BADICHEQ and BADICOaCH systems designed in Germany in 1991, the battery management system used by the General Motors EV1 in the United States, and the high-performance battery management system called BatOpt developed by the American ACpropulsion Company.

The earliest important thing in China is that some colleges and universities rely on their own scientific and technological advantages to cooperate with some large automobile and battery manufacturers to carry out some research work. Tsinghua University has equipped the battery management system for the EV-6568 light electric bus, and Tongji University and Beijing Xingheng have jointly developed a battery management system. Lithium-ion battery management system, Chunlan Research Institute developed HEV-BMS system, Beijing Institute of Technology and Northern Jiaotong University, etc. relying on the national 863 plan electric vehicle major special sub-projects, also developed a unique battery management system. With the launch of the electric vehicle market, many commercialized products have gained high-volume applications.

3. Research content of battery management system

First of all, to study the battery management system, generally study the single-chip microcomputer as the core, and the vehicle network as the distribution system. Sensing is then investigated, as the parameters of the battery are to be detected. Generally detect voltage, current and temperature. The transmission of data and control needs network to realize, generally use CAN network. The actuator is realized by display screen, relay, fan, pump, motor, etc.



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