Research And Design Of Charger And BMS For Lithium Battery

A large number of new energy vehicles and a variety of portable electric tools in the wide use of rechargeable batteries, in order to meet the requirements of capacity and pressure, generally require more than one single battery in parallel. Due to the dispersion of the parameters of the monomer battery can lead to the problem of average current in the charging and discharging process, which will affect the efficiency and life of the battery. How to solve the above problems by Management System Battery(BMS) to solve the above problems has become a hot research topic in the field of battery charger design and battery management system.First of all, the paper takes the lithium battery as the research object, analyzes the electrochemical principle, the charge and discharge characteristics and the polarization phenomenon of the lithium battery. In the analysis of the charging method of the lithium battery, this paper uses three stage charging method, and builds the peripheral hardware circuit of DC/DC chip to design the lithium battery pack charger.And then the battery management system is studied. Because of the high accuracy of voltage monitoring and resolution of the battery system is particularly important sampling, this paper uses advanced LTC6804 acquisition chip. The system can sample the single voltage, the battery temperature and current, and the hardware and software of the system is debugged.At last, the research of equilibrium system is carried out. Aiming at the problem of slow speed, low efficiency and high heat generation, the double active balancing circuit based on flyback transformer is adopted. The equalization circuit can be of arbitrary two pieces of single battery equalization, the ampere hour integral method and open circuit voltage method combining equalization method. The simulation experiment on LTspice is carried out on the balance system. The experimental results show that the active equalization has good performance.The design, manufacture and debugging of the hardware and software of the charger are finished in the paper. And on the upper computer for the voltage, the remaining power display. The experimental results verify the hardware circuit design and the reliability of the balanced control method.