Integrated Single-Phase Inverter with an Auxiliary Step-Up Circuit for Low-Voltage Alternative Energy Source Applications

This paper presents a integrated single-phase inverter with both high step-up ratio and buck-boost capabilities for low voltage alternative energy sources applications. An 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 switches 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. Steady-state characteristics, performance analyses and comprehensive experimental results are made to show the merits of the proposed inverter.