The Design Of Bidirectional DC/DC And Energy Feedback System For Power Battery Formation

With a worldwide reduction of fossil energy and deterioration of environment,the demand for green energy,particularly the electric energy,is becoming apparent.In the automotive industry,electric vehicles are considered as an inevitable trend.As the core of electric vehicles,power batteries are closely related to battery formation,a process of optimizing the capacity and parameters of batteries through a series of charge and discharge process.Nevertheless,domestic equipment unusually adopts resistance to consume electric energy in the discharge process,which gives rise to energy wastes and low efficiency.Moreover,its functions are rather limited and cannot satisfy actual needs.Against this background,this thesis presents a bidirectional DC/DC device with energy feedback system to enhance battery formation.On the basis of the TMS320F2802 digital signal processor,this thesis proposes a digital bidirectional DC/DC with energy feedback system,through which users can not only customize charging and discharging process,but also feed the electric energy produced in discharge process back to the grid.Firstly,the working principle of DC/DC and energy feedback system is studied and quantitatively analyzed,and the topology of the DC/DC and energy feedback system is selected.Meanwhile,according to system requirements,the hardware circuit,involving power circuit,control circuit and data acquisition circuit,has been designed and the main components parameters have been determined.The power circuit part includes the main circuit design and the parameters determination of the capacitance,the inductance and the switching device.The control and data acquisition part include the TMS320F2802 control circuit,the power circuit,the data communication,the current,voltage signal acquisition,and the IGBT drive circuit.Secondly,the formation control program has been designed,and program design method,as well as program block diagram of each important module,has been given.The design of the system initialization program,the charging and discharging mode,the control method and control parameter of constant voltage charging and constant current charging and discharging,and the design of PWM interrupt service routine are described in detail.Finally,according to system design requirements,a system prototype has been made and a system test platform has been built.The bidirectional DC/DC charging and discharging function,the current voltage control precision and the energy feedback voltage current are tested respectively.The experimental results show that the proposed bidirectional DC/DC and energy feedback system can format batteries and enhance energy feedback in the discharge process effectively.