Interleaved High Gain Bidirectional DC-DC Converter

Recently,with rapid consumption of oil,coal,natural gas and other traditional fossil energy resource,the world energy crisis and environmental pollution problems become severe.Therefore,comprehensive development and utilization of green renewable energy has become a fundamental way to solve the problem.Represented by wind power and solar power,however,renewable energy has disadvantages of instability and intermittent performance.This may result in negative effects on the synchronization power generation system.Energy storage devices play a vital role in the renewable-energy based grid-connected distributed generation system.And usually the output voltage of energy storage devices are low while the the DC grid voltages are high.To address this issue,high voltage gain bi-directional DC-DC energy storage converters are required.Based on that,this paper puts forward a novel high voltage gain bidirectional DC-DC converter consisted of switched capacitors and coupled inductors.By utilizing series-connected coupled-inductors and swithed-capacitors,high voltage gain,reduced voltage/current stresses across switches,soft charging/discharging performance,as well as auto-current-sharing mechanism among each channel are achieved.The interleaved structure combined with switched capacitors was adopted to reduce current ripple at the low voltage side,thus enabling high power applications.In this report,we first review the status of high-voltage-ratio bidirectional DC-DC converters.Then the evolution of the proposed extensible topologies and the steady-state operating principle under both the inductor current continuous conduction mode and discontinuous conduction mode are presented.In the following,the performance and features such as voltage gain,voltage and current stress,and the auto-current-sharing mechanism that are realized by switched capacitors are verified;the optimal design of coupled-inductors and switched-capacitors based on small-signal model are given.A specific design of the driving circuit that facilitates actual applications is described.Finally,A 1 kW prototype converter,employing a hybrid configuration of SiC and Si MOSFETs,was constructed to verify the theoretical analysis,and achieved an optimal compromise between conversion efficiency and low-cost.