Low-loss, high power factor voltage supply using a capacitive idling converter

Capacitive idling power converters derived from the Cuk and SEPIC topologies can operate as power supplies with input power factor correction. These power converters allow soft-commutation of their power switches without the need of additional circuitry, making it possible to increase the switching frequency while maintaining high efficiency. A simple high-frequency transformer allows output isolation. The input current and output voltage can be controlled by commercial ICs. EMI filter requirements are minimized by operating in high switching frequency and continuous current mode. Detailed design guidelines and circuit analysis are presented together with experimental results on a 500 W, 100 kHz prototype