Research On Charging Strategy Of Polymer And Power Lithium-Ion Battery Pack

The worldwide attention of saving energy and protecting the environment promotes electric vehicles increasingly popular, however, the existence of much problems of battery used in electric vehicle have constrained its development and popularity. The destination of this paper is to investigate charge strategy of power polymer lithium batteries.Firstly, a lithium battery model in the MATLAB is established. The application problems of power lithium-ion battery is analyzed .The three main problems in the charging control strategy ,as fast charging method, balanced and series battery charging and discharging of the device, are investigated. A method of following maximum and acceptable charging current is raised to replace the traditional method of constant current and constant voltage; A supercapacitor-based equalizer for power lithium-ion battery is designed and electric vehicles charge-discharge controlling system based on matrix converter circuit program is proposed.Secondly, a simulation model of the charging used by proposed method is established . In this paper ,the fuzzy logic algorithm is used to control the charging current of the charger to make sure it follow the changes in the acceptable charging current. Simulation results show that the charging time is relatively shorten. the charge and discharge device models based on the three-phase/single-phase matrix converter is established in Simulink, and improving the SVPWM modulation is used to reduce the current distortion in the input side. A Simulink simulation model of the proposed equalization scheme is established, with fuzzy control algorithm to control the frequency and duration of the balancing current source. Simulation results show that the scheme can effectively improve the consistency of the voltage of the battery pack.Finally, principle experiment of the fast charging strategy and experiment of a balanced strategy based on super capacitors are conducted. Experimental results show that the charging time of the fast charging method can be relatively shorten, that the voltage of power lithium battery pack can be balanced effectively by the equalizer.