A power density optimization method for a power pulsation decoupling buffer in single-phase DC-AC converters

The goal of this work is to develop an analytical method to determine the optimum size of an active decoupling buffer in single phase DC-AC converters for the highest power density. The conventional method for active twice line frequency power pulsation decoupling is a structure commonly known as the full ripple port architecture. However, its high voltage stress and correspondingly large inductor volume become a bottleneck to improve its power density, and the large amount of power processed in the active converter increases the power losses, leading to large heat removal solutions. recently proposed series-stacked buffer architecture provides a way to reduce the buffer converter voltage stress, reduce the power conversion losses and balance the volume of passive components to achieve very high power density. This paper presents a design procedure of the series-stacked buffer architecture that optimizes the power density through mathematical derivations and numerical design examples. The design procedure is based on calculating the energy storage of the passive components as the optimization objective and analyzing the operation of the buffer converter that forms certain optimization constraints. A set of optimal design parameters is found by the method of Lagrange multipliers. A hardware prototype is developed under the guidance of this optimization and the high power density has been experimentally verified.