Research On Non-isolated Multiphase Interleaved Parallel High Gain Bidirectional DC/DC Converter

With the increasing consumption of traditional energy sources and the consequent environmental pollution problems,the development of new energy is extremely urgent.In the background of new energy being widely developed and utilized,new energy industries have received huge demand and development,such as photovoltaic systems,electric vehicles,and energy storage systems.Bidirectional DC/DC converter,as an important electric energy conversion device for the development and utilization of new energy,has great research value in practical applications.The non-isolated multiphase interleaved parallel high-gain bidirectional DC/DC converter has attracted wide attention in low-voltage,high-current input and high-voltage output applications due to its advantages of small size,low voltage stress,high efficiency and gain.For this reason,this article mainly focuses on the non-isolated multiphase interleaved parallel high-gain bidirectional DC/DC converter.First of all,the research background and development status of high-gain bidirectional converter are summarized.And non-isolated multiphase interleaved parallel high-gain bidirectional DC/DC converter is mainly analyzed and studied.The multiphase interleaved parallel high-gain bidirectional DC/DC converter with fix phase shifts is difficult to achieve phase-to-phase current sharing over a wide duty cycle.In this paper,a variable phase shift control strategy is proposed to further expand its current sharing range for converter.Under the proposed control strategy,the voltage gain,current and voltage stress of power switching devices are analyzed in detail.The operating principle for Boost and Buck mode of the converter is analyzed.Secondly,on the basis of the above analysis,a frequency conversion control strategy is proposed for the light load operation of the converter,which causes the converter always run in the boundary conduction mode and realizes the soft switch for the converter.In order to study the dynamic characteristics of small-signal components on mult-phase high-gain bidirectional DC/DC converter,the small-signal model of multiphase converter is established in Boost mode.In addition,according to the actual situation for the converter running at low voltage and large current,the loss model of the multiphase converter is established,and the main factors affecting the efficiency and output voltage are analyzed in detail.Finally,an experimental study is conducted on the multiphase high-gain bidirectional DC/DC converter.The control circuit,auxiliary power supply,sampling and driving circuit of the converter are designed respectively,and the overall software system design of the converter is completed.A 380 W,input voltage 2.4V~4V,output voltage 24V~48V,four-phase hardware prototype has been built.The experimental results verify the correctness and validity of theoretical analysis and design.