Soft-Switching Stack-Type Three-Level/Two-Level Hybrid Buck-Boost Converter With Reduced Inductor Current Ripple

The growing adoption of renewable energy and electrified transportation demands bidirectional DC-DC converters with enhanced performance. This paper investigates a stack-type three-level/two-level hybrid buck-boost (Stack-Type 3L/2L-BB) converter that overcomes conventional four-switch buck-boost (FSBB) limitations through half device voltage stress and extended voltage range. A novel modulation strategy enables full-range zero-voltage switching (ZVS) without snubber circuits, effectively eliminating switching losses. Subsequently, the operating conditions are categorized into different modes, and a multi-mode control strategy is introduced to minimize the inductor current ripple across the entire range of input voltage and output load. Finally, a 100 kHz 6.6 kW prototype with maximum efficiency of 99.3 % is conducted to verify the effectiveness of the proposed modulation and control strategies.