Quad-Port AC-DC-DC-AC Operation of Isolated Dual Three-Phase Active Bridge Converter

Abstract

This paper investigates the operation of the Dual Three-Phase Active Bridge (D3AB) converter topology as a multi-port converter, by taking the three-phase ac port and dc port on the primary side (ac(1) and dc(1)) and the galvanically isolated three-phase ac port and dc port on the secondary side (ac(2) and dc(2)) simultaneously into account. The basic working principle of the D3AB topology under multi-port operation and a strategy to achieve independent power transfer between the four ports are described. It is found that the realization of a power transfer between ac(1) and ac(2), which can be operated with different line voltages and line frequencies, is particularly challenging, as compared to dc(1)-dc(2) operation. Therefore, this mode of operation is further analyzed and suitable modulation schemes are developed to achieve sinusoidal ac currents, constant dc-link voltages, and reduced low-frequency power pulsations between the ac ports. The derived analytical results are verified by means of circuit simulations and experiments, for a primary-side ac rms phase voltage of 115V and line frequency of 50 Hz, a secondary-side ac rms phase voltage of 57.5V and line frequency of 77 Hz, and an output power of 675W.