Switched-Capacitor Differential Boost Inverter: Design, Modeling, and Control

This article addresses a single-stage bidirectional step-up inverter designed from the integration of a differential boost inverter and switched-capacitor (SC) cells. The conventional boost inverter, even being a step-up topology, presents a gain limitation due to losses, and therefore, does not fully attend the step-up specifications. The insertion of SC multiplier cells into it allows increasing its static gain without increasing the voltage stresses on its components. However, the resulting topology is nonlinear and contains a high amount of energy storage elements, which implies high-order models. In this article, static and dynamic analysis of the SC differential boost inverter is performed under different types of modulation. A generalized and reduced order equivalent circuit and a small-signal average model are proposed, as well as a static gain linearization technique that reduces the harmonic distortion of the output voltage, regulated in the closed loop by a resonant controller. This article also presents the main waveforms, equation, and a comparison between the differential boost inverter and its version with SC multiplier cells. To verify this study, a 250-W prototype of the rated power, input voltage of 60 V, switching frequency of 50 kHz, and the output voltage of 220 V is experimentally evaluated.