Control strategy of a solar power inverter (analysis of a seventh order system-II)

In conventional mains-coupled inverter topologies a multi-stage filter is used for grid coupling and to fulfill the EMI-requirements. This filter also unavoidably forms the required output characteristics (current source) of the inverter. The resulting structure leads to a high system order which is difficult to control and problematic to realize due to unknown mains impedance behavior. In case of the realization presented, two dedicated band-stop filter stages were used to enhance the output characteristics. The matching filter used in conjunction with an optimal controller can overcome most of the known limitations. In this paper it is shown that the optimal adaptation of the suggested structure leads to a simple, insensitive, easy to use and very robust solution.