Efficiency improvement of three port high frequency transformer isolated triple active bridge converter

摘要

This paper discusses and compares few techniques for efficiency improvement of Three-port Triple Active Bridge(TAB) Converter. Transformer isolated three port phase shifted Triple Active Bridge dc-dc converters are very efficient in nature providing high efficiency, ZVS operation over wide range, galvanic isolation and bidirectional power flow capability. The natural turn-on ZVS for switching devices in DAB or TAB converters is a very useful property for using Mosfets, as it reduces the device losses by a huge margin. The natural ZVS is lost for phase shifted converters at low power operating regions, causing reduction in efficiency. This paper discusses a comparsion between phase shift operation at fixed frequency vs phase shift operation at varying frequency and varying duty cycle operation at fixed frequency, which leads to a greater operating range of natural turn-on ZVS thus improving the efficiency. A comparison of the three methods have been presented in this paper with experimental results from a 10kW hardware prototype made of SiC Mosfets.