Lithium Electric Vehicle Battery Management System Research And Design

Problems caused by energy and environment are more serious in21st century. The development of Electric Vehicle (EV) will help to ease the problems of energy’s shortage and environmental pollution. The li-ion battery has many advantages, such as that it’s a green energy, and it has high specific energy, so it is applied at EV widely recent years. The working status of li-ion battery is very important for driving safely. The battery needs to be managed through the Battery Management System (BMS), which monitors the working status of the batteries, prevents of overcharge and over discharge accidents, manages the energy, improves the utilization and extends the life of the batteries.The characteristics of li-ion battery, the factors affecting the State Of Charge (SOC) of li-ion battery, several representative methods to estimate the SOC are firstly analyzed. The method of combination of Coulomb Counting method and Open-Circuit Voltage method is used to estimate the SOC.A BMS is designed, and the designs of hardware and software are also introduced in detail. The voltage, current and temperature are monitored when the li-ion batteries are in charge, discharge or idle state, the SOC is estimated, the energy is managed with reasonable balance strategy and the safe operation of li-ion batteries is protected through the BMS. CAN bus communication is used in the system, which has strong anti-jamming capability.Experiments show that the expected goals are achieved. The working status of li-ion batteries is monitored real-timely, and the safe operation of li-ion batteries is protected well through the BMS. The system costs lower, and the reliability of the hardware and software is high.