Model of HF-Transformer for Full-Bridge DC-DC Converter

Abstract

This paper presents a comprehensive design and simulation study of a high-frequency transformer for a full-bridge isolated DC-DC converter. The transformer parameters, including turns ratio, number of turns, magnetizing and leakage inductances, winding resistances, and core geometry, are calculated for a $1 ~\text{kW}, 50 \text{kHz}$ converter with a 300 V input and 110 V output. Based on the calculated parameters, a simulation model is developed in MATLAB/Simulink. The simulation results show that the designed transformer fails to meet the required output specifications: the output voltage drops to 69 V instead of 110 V, and the output power reaches only 394 W instead of 1 kW, primarily due to the significant voltage drop across the leakage inductances. The transformer efficiency is 95.8%, while the overall converter efficiency is 92.7%. The findings highlight the necessity of accounting for parasitic leakage inductances in the design procedure and suggest potential solutions, such as sandwich winding technique, correction of the turns ratio, or series capacitive compensation. The proposed methodology enables systematic parameter estimation but requires iterative refinement to achieve target output characteristics.