A Three-Phase Dual-Active-Bridge DC-DC Immittance Converter

A three-phase dual-active-bridge (3p-DAB) DC-DC converter employing three-phase resonant immittance network (3p-RIN) has been proposed in this paper to attain unity power factor operation at both ac-links of the 3p-DAB converter for mitigating the reactive power loss. Besides unity power factor operation, the proposed converter can perform full ZVS operation as well for all the switches to minimize the switching power loss. The unity power factor operation is performed by keeping the primary and secondary bridge voltages in phase whereas the full ZVS operation is performed by keeping the primary and secondary bridge voltages in lagging phase relationship. For unity power factor operation, the power flow through the converter is regulated by modulating the internal phase shift angle, whereas for full ZVS operation, the power flow is modulated utilizing both internal and external phase-shift angles. Fundamental component analysis for voltages and currents of 3p-RIN is used to carry out the detailed modeling of the converter followed by the validation from a 400 V/220 V, 2 kW hardware prototype for benchmarking the cogency of the proposed topology. The hardware prototype has been operated in both unity power factor and full ZVS modes of operation. More superior performance was discerned for the unity power factor operation as compared to the full ZVS mode of operation for the selected specifications of the prototype.