The Research Of Bidirectional DC/DC Converter For Electric Vehicles

With the energy crisis and environmental pollution are becoming seriously outstanding,electric vehicle has become a new trend of automotive industry because of its advantages of high efficiency and environment protection.In the promotion and application of electric vehicles,energy management is central to development of electric vehicles.It is well known that bidirectional DC/DC converter used for improve the performance of electric vehicle.Therefore,the research of high efficiency,lo w voltage,high current and fast response speed bidirectional DC/DC converter technology is the key to the development of hybrid electric vehicles.Firstly,this paper introduce the background of the electric vehicle and the research status of bidirectional DC/DC converter.The characteristics of the bidirectional DC/DC converter in the hybrid power supply system are analyzed in detail.Based on the summarizing of common circuits,an improved topology of bidirectional DC/DC converter used to solve the problems during use it.Based on the three-teminal network of traditional interleaved buck converter,through the introduction of switched capacitor to reduce the equivalent input voltage the high step-up bidirectional DC/DC converter is proposed in this paper.The operation principle and property of the converter in boost and buck modes were analyzed in detail.The ripple is decreased and the voltage gain is higher in the same duty while compared with the traditional converter.At the same time,the voltage stress of the switches are reduced.Finally,the simulation is built to verify the theoretical analysis.Then,a small single mode of a novel interleaved parallel bidirectional DC/DC Converter operating in Boost and buck mode were derived by state-space averaging method.Based on the analyze of frequency domain characteristics and bode diagram,dual-loop PID control of voltage and current are used to improving system stability and dynamic response speed.At the same time,the simulation is built by Matlab/simulink to verify the reasonableness of controller.Finally,a 400 W prototype are done to verify the theoretical analysis is correct.The parameters and loss with inductor and switch tube of improvement interleaved parallel bidirectional DC/DC Converter are expounded.It is also introduced some key hardware such as Mosfet diver circuit,sample conditioning circuit,auxiliary power supply circuit.At the same time,steady state experiments are carried out to verify the correctness of the theoretical analysis in this paper.