A high performance controller for a single phase cascaded multilevel photovoltaic system

This paper presents a high performance control strategy for a single phase photovoltaic system based on cascaded multilevel converter. The concept of single phase d-q vector control is introduced into the system and a general control scheme for arbitrary number of modules is proposed. The proposed method can not only track the maximum power point at panel level but also ensures a high performance current tracking in grid side. Therefore, the high efficiency system can be obtained. Correspondingly, the detailed control law is derived and design considerations are given. Lastly, a PV system interfaced by a cascaded seven-level converter is studied and experimental results are presented for verification purpose.