High-Frequency Magnetic Integration Planar Transformer Design for DCZVS Converters

This paper presents a high-frequency magnetically integrated planar transformer design methodology. During the operation of a DCZVS converter, a resonant inductor is required to resonate with a clamping capacitor. Energy storage components typically occupy a large portion of the weight and volume in converters. As an isolated topology, the Double-clamped ZVS (DCZVS) converter includes an isolation transformer; here, magnetic integration leverages the transformer's leakage inductance as the resonant inductor. This approach effectively reduces the use of magnetic components, thereby increasing the converter's power density. Digital control enables operation at high switching frequencies, where the challenge of controlling transformer leakage inductance increases due to pronounced skin and proximity effects. In particular, for magnetically integrated planar transformers, the transformer's leakage inductance must be strictly controlled to meet design specifications, as it serves as the resonant inductor. This study optimizes core selection and PCB winding structure to improve winding coupling coefficients, minimizing transformer leakage inductance. This reduction not only decreases transformer losses but also provides a predictable leakage inductance that supports the design of other resonant components. Through extensive design and optimization, the parameters of the transformer were determined, and the effectiveness of the transformer design was validated through finite element and circuit simulation analysis.