The reliability of power converters is intricately tied to the variations in the junction temperature of semiconductor devices. Therefore, possessing accurate models of these components is of paramount importance. This research introduces an electrothermal model focusing on Gallium Nitride (GaN) based DC-DC converters. The experimental evaluation leverages a GaN-based Two-Level Buck Converter (TLBC), where current control is achieved via pulse width modulation (PWM), while a comprehensive thermal model is developed in the range of 10 to 500 kHz at fixed switching frequencies. The test-bed involves direct temperature measurement utilizing infrared thermal sensors. The proposed model undergoes validation through comparison with experimental data in steady-state and dynamic conditions. Finally, the contribution of this work is to generate an accurate electrothermal model of a Two-level Buck Converter based on GaN-HEMT technology transistors to enable active thermal control (ATC) implementation in steady-state and dynamic mode. The aim of the study is to address the management of component temperature rise given the need for full integration requirements as a major challenge in new-generation of DC-DC power converters

DC–DC power converters are essential for various applications, including photovoltaic systems, green hydrogen production, battery charging, and DC microgrids. Partial Power Converters (PPC) are notable for their efficiency, processing only a fraction of total power and reducing conversion losses, but this performance is overshadowed by the high cost of its construction, associated with high-frequency transformers (HFT). This paper introduces a transformerless partial power AC-link step-down converter, eliminating the need for an HFT and reducing costs while improving power density. An experimental validation using a reduced-scale prototype demonstrates the converter’s operation with a peak efficiency of 93.2% and overall efficiency above 92%, demonstrating the experimental viability of the converter. The proposed AC-link seen as a two-port network is shown to be very attractive for DC–DC step-down operations, and as a possible replacement of traditional PPC.