Swinging bus inverters: New requirements in renewable power and the Natural Switching Surface

This work presents the analysis of a swinging bus inverter for renewable power applications. The bus is employed to absorb the ripple current from the inverter to avoid detrimental reflection into the power source. Since inverters are traditionally operated with stiff dc input voltages, the low frequency voltage swing (120 Hz and harmonics) at the input terminals of the inverter presents an unprecedented challenge for the control scheme of the converter. A possible solution based on boundary control is proposed and the natural trajectories are used as the analytical framework for the study. Experimental results are presented to illustrate the inverter operation under the Natural Switching Surface (NSS) with excellent steady and dynamic characteristics.