Low-loss converters with high step-up conversion ratio working at the border between continuous and discontinuous mode

The use of tapped inductors in the classical boost or buck-boost converter leads to a high step-up ratio thus avoiding the extreme duty cycles of the active switch and the high peak currents in the active and passive switches. Two converters are presented and analyzed. Due to the simultaneous regulation of the switching frequency and the duty cycle on one hand and the winding ratio of an autotransformer on the other, high conversion rates of 1:5 can easily be realized. The dimensioning of the converters, their dynamical behavior, and the component stresses are analyzed.