DC converter with three circuit cells – analysis, design and experimental evaluation

Abstract

A new DC/DC converter with three circuit cells has been presented. For high input voltage applications, two-input split capacitors with four active switches are used in the proposed converter to limit the voltage stress of each power switch at one-half of input voltage. Thus, power metal-oxide semiconductor field-effect transistors (MOSFETs) with 500 V voltage rating can be adopted for 1000 V input voltage applications. Two balance capacitors are adopted in the proposed circuit to automatically balance two split input capacitor voltages in each switching cycle. Three resonant tanks are used at primary side of the proposed converter to share the load current and reduce the current stress of passive components. Thus, the sizes of the magnetic core and bobbin are reduced. If the operating switching frequency is less than the series resonant frequency, power MOSFETs are turned on at zero-voltage switching and rectifier diodes can be turned off at zero current switching. Thus, the switching losses on power semiconductors are reduced. Finally, experiments with a 1.5 kW prototype are provided to verify the effectiveness of the proposed converter.