A study on Switching Frequency Selection of a GaN-Based Non-Inverting Buck-Boost Converter for Wearable Robot Power Supplies

This study quantitatively investigates the trade-off between power density and semiconductor loss as a function of switching frequency in a GaN-based four-switch non-inverting buck–boost converter for wearable-robot power applications and proposes a recommended switching frequency range. Well suited to mobile power systems with wide input-voltage variation, the non-inverting buck–boost converter supports non-inverted step-up and step-down operation, while the four-switch topology enables a single-inductor implementation that reduces passive components and footprint. When the input and output voltages are comparable, all four switches may commutate within one switching period, increasing loss; under high-frequency hard switching, switching loss can dominate and impose thermal and efficiency penalties. The converter is evaluated over an input-voltage range of 30 to 54.6 V with a 48 V/400 W output while sweeping switching frequency from 100 kHz to 1 MHz. Conduction and switching losses are evaluated separately to capture loss trends versus switching frequency and input voltage. To represent inductor burden consistently, an inductor-current-based energy proxy is defined over a steady-state time window. A Pareto plot using the energy proxy and total semiconductor loss identifies operating points that balance compactness and loss, providing a practical guideline for switching frequency selection.