The transition from the conventional electrical power distribution system to ones that incorporate more stochastic electrical sources is resulting in a need for more robust and dynamic forms of power delivery. One solution to the various issues of power balancing and control is the utilization of additional frequencies within the distribution network. By having a greater variety of operational frequencies, the resulting decoupled power flow enables the system to have a higher degree of flexibility and functionality. This paper presents a controller for load-interfacing power electronic converters that operate within a system consisting of several ac frequencies as well as a superposed dc offset. The power exchange capabilities of this multifrequency converter, such as the decoupled power transfer between different operating frequencies are analyzed and demonstrated. Likewise, the underlying control structure is easily modifiable for a wide range of frequency combinations. The resulting increased level of active and reactive power control can then be utilized by the distribution network to ensure a more enhanced and stable transition to an electrically diverse and smarter microgrid. Simulation results for several different operating points are presented.

An Active-Bridge based, current-source, three-phase inverter (3PAB) is proposed. It is a single-stage, galvanically-isolated topology, which enables direct interface to a three-phase grid. Operation is similar to a Dual Active Bridge converter, in which the secondary side H-bridge is replaced with a three-phase bridge. A novel modulation technique presented in the paper enables unidirectional power flow from DC to AC side, while energizing all three output phases in one link cycle. Zero voltage, zero-current turn-on of all devices reduces switching losses and increases efficiency. The proposed topology is a viable solution for applications where a compact and lightweight, galvanically-isolated inverter is required such as roof-Top photovoltaic installations.