Research And Design Of The Key Technologies In Battery Management System For Pure Electric Vehicles

Since the beginning of 2013, sustained haze weather has occurred in most areas of China. Almost 1/4 of the mainland and 600 million people are affected. One of the main reasons which caused this situation is the vehicle exhaust which makes PM2.5 of the city air in 60% part. So, energy saving and emission reduction have become the government’s first goal and the people’s ardent expectation. Comparing to the traditional fossil-fueled vehicles, electric vehicles can effectively reduce the exhausted tail gas and have become the new direction of energy efficiency and environmental protection in transportation field.Dynamic batteries supply the power to new energy vehicles, and a safe and efficient management of these batteries has been one of the key technologies. A complete battery management system(BMS) has the quality to monitor the batteries’ states, exchange the information, make them safe and have a secure, reasonable and efficient use of the power during the driving.Two key technologies in BMS, including SOC and batteries’ balanced control, were researched and designed in this paper.In the research of SOC, an algorithm based on BP neural network was adopted comparing to other traditional ways. It was simulated in MATLAB and proved to have good curve of charge and discharge fitting characteristics, relatively high reliability and precision. Then relying on the automatic code generation, C code of the algorithm was successfully generated and transplanted in DSP working well.In the aspect of battery’s balanced control, a non dissipative equalization circuit composed of inductors was designed, aiming at transferring the energy without loss. According to the simulation, it approved this circuit has the feasibility and efficiency. After calculating, all electric elements in need were chosen and the circuit was set up. Cooperated with corresponding control algorithm, it realized the designing purpose well.Besides, this paper completed the design of main circuit of BMS, in which TMS320F2812 worked as control chip, including AD data acquisition circuit, IO isolated output circuit, CAN communication circuit, SPI communication circuit, RTC clock, extended 64 K RAM and so on. With the programmable resistor load, it realized the debug of main control board, data acquisition board and equalization board. The function tests of SOC estimation and balanced control were all proved to be good.