Direct Isolated AC-AC Converters For Low-Power Applications

Compact, energy-efficient power supplies are essential to meet the rising demand for safe and sustainable consumer electronics. A defining feature of next-generation power supplies is their ability to deliver high-frequency AC power directly from the wall outlet—an innovation that is vital for advancing emerging applications with wireless power transfer (WPT) capability and ultrasonic motor driven products. Currently, offline power supplies for such applications typically rely on multi-stage conversion architectures that are achieved through combination of disparate topologies or the adaptation of legacy designs. Such designs increase system size, power loss, and control complexity, which hinder integration and also increase product cost. To address this challenge, we propose a type of isolated direct offline AC-AC converters that process 50/60 Hz mains voltage directly into high-frequency AC output through a single-stage power conversion. This approach integrates galvanic isolation, simplified structure, and control, offering a compact, efficient, safe, and low-cost solution for powering high-frequency AC loads. The proposed converter delivers several advantages over existing systems: • Higher power transfer efficiency • Smaller size and higher power density • Single active power stage • Simplified control and design • Enhanced integration for modular systems Impact on the Wireless Power Transfer Industry: The converter eliminates intermediate stages in WPT systems, reducing energy loss and system complexity. This enables the development of compact and efficient wireless charging platforms for consumer electronics and medical devices, supporting the growth of WPT adoption fueled by the integration of emerging Qi2 and MagSafe-like standards.