Research On Topology And Constructon Of Impedance-Source Step-Up DC-DC Converters

High step-up dc-dc converters have been widely used in industry applications,such as high intensity discharge lamp,battery backup system for uninterruptible power supply,electric vehicle,photovoltaic,and fuel-cell power systems.Due to the influence of the parasitic parameters,the voltage gain of the traditional boost converter is limited.Therefore,the novel high step-up dc-dc converters are desired to develop.The impedance-source networks are composed of inductors,capacitors,and diodes,which can be applied to dc-ac,dc-dc,ac-ac,and ac-dc power conversion.Therefore,this thesis applies the impedance-source networks to dc-dc converters with their boost abilities,and proposes a family of impedance-source step-up dc-dc converters.The topology construction and derivation methods based on impedance-source converter are summarized.The main works are as follows:1.The current research status of the impedance-source converters and some basic impedance-source networks are introduced.This thesis analyzes the voltage boost principles and structure characteristics of the basic impedance-source networks.Their features are also summarized to provide construction directions for the impedance-source step-up dc-dc converters.2.To overcome the drawbacks of the traditional impedance-source networks,this thesis proposes a family of hybrid impedance-source network,which is obtained by combining the traditional impedance-source networks.The proposed converters can realize a high voltage gain with a small duty cycle,which are very suited for renewable energy power systems.Moreover,the proposed construction methods can be applied to the constructions of the impedance-source networks and high step-up dc-dc converters.3.In the convertional impedance-source converters,the impedance-source networks are usually located between input and output.This thesis changes the positions of input and output and proposes a family of commom grouded impedance-source dc-dc converters.The first method is to locate the output between input and impedance-source network,thus the input and output share the same ground.However,the obtained converter has a higher voltage gain and reduces the switching device stress.The second method is to locate the input between impedance-source network and output.The voltage gain is the same as the original converter,but it reduces the capacitor voltage stress effectively.The proposed converters have good practicabilitie with their advantages.4.Prototypes of the proposed converters are built in laboratory.The simulation and experimental results are given to verify the validity of the proposed converters.Finally,the summary and prospect on impedance-source step-up dc-dc converters are made.The innovations of this thesis include the presentation of hybrid impedance-source networks and improvements on the traditional impedance-source dc-dc converter.