Reduction of Capacitance in Four-Switch quasi-Switched Boost Inverter using Low-frequency Ripple Damping Scheme

In this paper, a Four-Switch quasi-Switched Boost Inverter (FS-qSBI) is derived from the embedded type-2 qSBI topology. It has all the advantages of qSBIs such as continuous input current, higher ac output voltage, simultaneous operation with both ac and dc loads, and shoot-through immunity. Additionally, it has one less switch and one more capacitor compared to the qSBIs. In order to address the inherent dc-side low-frequency ripple issue of FS-qSBI, this paper also proposes a low-frequency ripple damping scheme so that size of the capacitor can be significantly reduced without using any additional hardware component. Thus, highly reliable film capacitors can be used instead of conventional electrolytic capacitors, which results in improved power density, system lifetime and reliability. A stability analysis of the system, exploring the impact of capacitor reduction, is also presented. The FS-qSBI is implemented in hardware to verify the theoretical analysis and the proposed low-frequency ripple damping scheme.