ISOLATED DC-TO-DC VOLTAGE STEP-UP CONVERTER

摘要

An isolated DC-to-DC voltage step-up converter is provided with four switches, an input inductor, an isolation transformer, two resonant inductors and two resonant capacitors and operates with two distinct intervals: ON-time interval and an OFF-time interval. The two half-wave sinusoidal resonant capacitor charge and discharge intervals, one during the ON-time interval and the other during the OFF-time interval are chosen as to eliminate the losses due to energy stored in the leakage inductance of the isolation transformer and to operates with zero voltage switching of the primary side switches. It provides the output voltage regulation over the wide input voltage range with the same low voltage stresses of all four switching devices. The isolation transformer has full bi-directional flux capability and has DC bias. Despite the two independently controlled resonances, the output voltage is controlled by the duty ratio D control at constant switching frequency.