Two-Mode Controlled Single/Dual-Input DC–AC Inverter With Wide-Range DC Input

This article presents a two-mode controlled step-up inverter (TMCSI), which is capable of handling single or dual inputs with a wide range of dc input voltage. In comparison to traditional multistage dc/dc power conversion systems, the power conversion stage is reduced and the voltage/current stress of device is significantly alleviated without using high-voltage dc-bus capacitors. As a result, the reliability and overall conversion efficiency are improved accordingly. By combining the two working modes, the proposed inverter achieves uniform distribution of duty ratio under single/dual-input with a wide range of input voltage, and thereby is very suitable for systems having large input voltage variation. Moreover, based on the dual-input TMCSI, a novel power allocation method is also proposed to improve the system load-bearing ability. The power allocation method is controlled separately from two working modes that allows the two-input sources directly supply the ac load simultaneously. In this article, topology derivation, two-mode control strategy, characteristics of steady principle, and design criteria for the key circuit parameters are systematically analyzed, and important conclusions are obtained. Finally, the experimental results from the single/dual-input 500 VA 96-192 V
_dc
input and 220 V
_ac
/50 Hz output inverter prototype verify the effectiveness of the proposed TMCSI topology and its associated power regulation approach.