As a core component of switch-mode power supplies (SMPS), the miniaturization of electronic transformers is key to driving the lightweighting and high power density of SMPS. Leveraging high-frequency technology, material innovation, structural optimization, and process upgrades, electronic transformers can significantly reduce their size while ensuring energy conversion efficiency and reliability, adapting to the compact design requirements of consumer electronics, new energy vehicles, AI servers, and other scenarios. Their miniaturization path has formed a multi-dimensional technological system.
High-frequency operation is the core physical foundation of electronic transformer miniaturization. According to the electromagnetic induction formula, when the voltage and magnetic flux density of the core are fixed, the operating frequency is inversely proportional to the number of coil turns and the cross-sectional area of the core. Traditional power frequency transformers operate at only 50/60Hz, requiring thick cores and numerous windings; while electronic transformers, by incorporating third-generation semiconductor devices such as GaN and SiC, can increase the operating frequency to tens of kHz to several MHz, significantly reducing the number of coil turns and the size of the core. For example, theoretically, increasing the frequency from 20kHz to 200kHz can reduce the volume to 1/10 of its original size. Combined with a fast-charging adapter for mobile phones with MHz-level switching frequencies, this could achieve a credit card-level compact design. However, it's important to note the diminishing returns of higher frequencies; excessive frequency increases can lead to a surge in losses, requiring a balance between materials and processes to achieve optimal performance.
Novel core materials and structural designs provide performance support for miniaturization. The core is the core component of an electronic transformer, making the application of low-loss, high-permeability materials crucial. For high-frequency applications, manganese-zinc ferrite and amorphous/nanocrystalline alloy cores are preferred, as their high-frequency losses are significantly lower than traditional silicon steel sheets. Combined with optimized magnetic gap design, magnetic saturation can be suppressed, controlling temperature rise while reducing volume. Advanced solutions employ hybrid core technology, fusing ferrite and nanocrystalline materials into a single magnetic plate. Adaptive materials are used for different magnetic field strengths in different regions, balancing losses, weight, and cost. Co-fired copper-iron integrated molding processes achieve integrated core and winding by co-firing magnetic slurry and copper conductive slurry, significantly improving power density and meeting the high-current, small-size requirements of AI servers.
Innovations in winding and structure further compress space and optimize performance. Planar transformer structures are the mainstream solution, replacing traditional wire windings with flat copper foil windings. Through PCB stacking and printing, the height can be significantly reduced, while increasing heat dissipation area, reducing leakage inductance, and improving coupling efficiency, making it suitable for thin devices. Integrated design merges electronic transformers and inductors; for example, in LLC resonant topologies, the resonant inductor is integrated into the transformer core, reducing the number of components while precisely controlling leakage inductance, resulting in a volume reduction of over 30%. Three-dimensional coiled integrated structures, utilizing nano-soft magnetic materials, achieve a two-order-of-magnetic-magnetic-area density increase in on-chip inductor area, providing an ultra-miniaturized solution for RF applications.
Process upgrades and topology optimization solidify the foundation for miniaturized reliability. Automated precision manufacturing processes improve winding consistency and reduce redundant space; technologies such as precision stacking printing and laser-cut copper foil ensure conductivity and insulation reliability in small sizes. Meanwhile, by optimizing the transformer design based on the characteristics of SMPS topology, the multi-winding structure can adapt to multi-port power supply requirements, simplifying the system structure; the dual-frequency converter's magnetic integration further reduces the overall size by merging high-frequency and low-frequency inductors. Through the synergy of these technologies, the electronic transformer can maintain high efficiency and low interference characteristics while significantly reducing its size, becoming a core support for modern precision power supply design.