Design of Parallel Inverters for Smooth Mode Transfer Microgrid Applications

In this paper, a microgrid architecture comprised of parallel inverters, critical loads, and CAN communication is studied. The controller designs in both grid-tie and islanding modes for the designed MG system are described. How to distribute the currents among paralleled inverters with CAN bus as communication interface is addressed. The mode transfer tests are conducted with an inverter-simulated grid to define the proper transfer procedures. Experimental results show that the inverter can work properly in different basic microgrid operation modes. With current sharing scheme, the output current is equally shared among different inverters without noticeable circulating current. Both the simulation and experimental results of mode transfer show that the inverter can switch between grid-tie and islanding modes smoothly, which indicates that the proposed mode transfer procedure is capable of minimizing the transients during mode transfer.