An Integrated Arm and Integrated Three-Phase Module DC-AC Modular Converter with Minimal Energy Storage Requirements

Modular converters gained popularity in low to high voltage applications since it was first introduced in early 2000s due to the design flexibility. Conventional modular converters require large submodule capacitance to accommodate single-phase AC processing power requirement that lead to the use of electrolytic capacitors. The use of electrolytic capacitor in each submodule increases the converter volume and affects the efficiency of the converter. This paper presents an integrated modular topology with integrated positive and negative arms and integrated half-bridge modules. The proposed circuit design permits significant reduction in energy storage requirement due to energy balance per switching cycle and thus a tiny shared capacitor (few micro-farads versus several milli-farads). The number of capacitors required in the converter is also reduced significantly because only one capacitor is needed between the positive and negative arms. The work is verified experimentally using a laboratory-scale prototype and circuit simulations.