A Novel High Step-Up Ratio Inverter for Distributed Energy Resources (DERs)

A novel inverter with both high step-up ratio and buck-boost capabilities for distributed energy resources (DERs) is proposed in this paper. A flyback-type auxiliary step-up circuit is integrated to the isolated Cuk-derived VSI to achieve a much higher voltage conversion ratio while avoiding the use of extreme duty ratios of both dc-side switch and inverter side switches. The proposed inverter can naturally perform capacitive charging in parallel and discharging in series to give a higher voltage level without increasing dc-side switch voltage stress and sacrificing the buck-boost characteristics of the ac output voltage. In this paper, steady state characteristics, performance analyses and representative simulations are made to show the merits of the proposed inverter.