A 9-kW Floating Four-Arm Interleaved Step-Up Converter With 98.7% Efficiency and Low Ripple for Grid-Connected PV Systems

Abstract

The deployment of next-generation ultra-high-power tandem photovoltaic (PV) modules demands front-end DC-DC converters capable of processing high input currents while achieving large DC voltage gain. However, conventional high-gain topologies are often constrained by excessive component stresses, elevated device counts, and efficiency degradation caused by parasitic effects. To address these challenges, this paper proposes a step-up DC-DC converter termed the Symmetrical Floating Four-Arm Interleaved Boost Converter (FFIB). The proposed topology employs only two inductors and inherently balances the currents among four interleaved arms without auxiliary balancing circuits or complex control strategies. Through an optimized interleaving scheme, the apparent input and output ripple frequencies are increased to four times the switching frequency, while internal passive-component ripple frequencies operate at twice the switching frequency, significantly reducing filtering requirements, magnetic volume, and conduction losses. A comprehensive theoretical investigation is conducted, including operating-principle analysis, steady-state modeling, voltage-gain derivation, component stress evaluation, and design-oriented sizing methodology. The proposed FFIB converter is experimentally validated using a 9 kW laboratory prototype under various operating conditions. Experimental results demonstrate peak efficiencies of 98.7% for 350V/600 V operation and 98.32% for 300 V/ 990 V operation. These results demonstrate that the proposed FFIB converter constitutes a highly efficient, low-ripple, and compact solution for emerging grid-connected ultra-high-power tandem PV systems requiring simultaneous high-current processing and large DC voltage gain.