A Scalable Electronic-Embedded Transformer, a New Concept Toward Ultra-High-Frequency High-Power Transformer in DC–DC Converters

The demand for a high-power and high-density isolated dc–dc converter is driven by the rapid development of energy storage system, data center power supplies, and transportation electrification. However, designing a high-power and high-frequency transformer presents significant challenges due to the tradeoff between thermal management, leakage inductance minimization, and insulation requirements. In order to overcome this tradeoff between power rating and operation frequency, a scalable electronic-embedded transformer (EET) is proposed with a low-voltage bridge integrated into the transformer windings. The EET addresses the challenge through its simple open-loop control and natural current sharing, enabling easy parallel connection and scaling to different power ratings. Based on this concept, a bidirectional EET-based dc transformer (EET-DCX) is proposed to solve the transformer-level paralleling and resonant point shift issues in traditional LLC-DCX designs. By employing the embedded full bridge, the EET-DCX effectively cancels out the impedance of the leakage inductance, ensuring optimal operation at any frequency. Additionally, the EET-DCX retains the inherent advantages of the LLC-DCX, such as load-independent voltage gain, simple open-loop control, full load range zero voltage switching (ZVS), and low circulating current. Leveraging these advantages, the proposed EET-DCX solution has the potential to push the boundaries of transformer performance to the megahertz operation frequency range with hundreds of kilowatts power capability. To validate these merits, a 12-kW 500-kHz EET-DCX with four planar EET units was built. This article is accompanied by two videos demonstrating the dynamic load changing and frequency changing test.