A High-Input Voltage Two-Phase Series-Capacitor DC-DC Buck Converter

A high-input voltage 2-phase series-capacitor (2-pscB) DC-DC buck converter is theoretically analyzed, designed, and implemented. A new design approach for an automatic current sharing scheme was presented for a 2-phase series-capacitor synchronous buck converter. The series-capacitor voltage is used to achieve current sharing between phases without a current sensing circuit or external control loop as each phase inductor charges and discharges the series capacitor to maintain its average capacitor voltage constant. A novel isolated gate driver circuit to accommodate an energy storage capacitor is proposed to deliver isolated gate voltages to the switching transistors. An I2 control scheme that uses only one feedback path control for the four gate drivers is proposed to enable higher voltage conversion. An experimental 110-12 V 6 A load prototype converter was designed, and its current sharing characteristics were experimentally verified.