Study On Bi-directional DC/DC Converter With High Conversion Ratio

:The high conversion ratio bi-directional DC/DC converter is widely applied in charge and discharge battery systems, automatic cars, uninterruptible power supplies (UPS),photovoltaic systems, generator systems and aero power supplies, etc. The efficiency, quality and cost are the key properties for these applications. A novel coupled-inductor bi-directional DC/DC converter is proposed and analyzed in this paper, which can overcome the shortage of non-isolated bi-directional DC-DC converters that its conversion ratio is restricted in a small range and achieve high conversion ratio and high efficiency.Firstly, this thesis introduced the working principle of high conversion ratio bi-directional DC/DC converter. Then the coupled inductor and main circuit parameters design methods are studied, and the design principles and constraints of the key parameters are given. The simulation models are built on the base of Matlab/Simulink software, simulation results indicate the effect of these proposed control strategies.Furthermore, the mathematical models of high conversion ratio bi-directional DC/DC converter were studied. Using the state space averaging method, the small-signal model of buck and boost converter with the continuous current is given. The parasitic effects on stability and closed loop regulation have been made extensively. It also designs the main circuit, control circuit, drive circuit and protection circuit of the converter and analyzes the voltage stress of MOSFET in different power flow, and the suppression measures are presented.At last, the high conversion ratio bi-directional DC/DC converter uses DSP control, Choosing the TMS320F28335chip as the core of the control. The complete design parameters, control system structure, and software flow chart of experimental prototype were given in this thesis. The experimental platform was established, and then the system experiments of the prototype were done. The results of system experiments were analyzed, and the results showed that the proposed control strategy was effective.