Single-switch three-level DC-DC converters for dimmable LED lighting

A novel single-switch three-level (TL) converter is proposed for dimmable LED lighting. Compared with standard TL converters, the proposed topology not only maintains the advantage of using a lower voltage rating power switch that is rated half the input voltage, but also eliminates one active switch and its associated driving circuit. Moreover, it can naturally solve the voltage stress imbalance issue because of the resonant flying capacitor. The operation principle and dimming scheme of the proposed TL converters have been described. A prototype of 46-W dimmable LED driving converter has been implemented to verify the designs and analyses. The experimental result shows that single-switch TL buck converter can regulate the LED current from zero to the desired 1 A with fast slew rate. A peak efficiency of 98% was achieved with 400 kHz switching frequency.