Individual MPPTs of single-phase three-level split DC-bus inverter

This paper proposes a single-phase three-level split DC-bus inverter for individual maximum power point tracking (MPPT) controls. With only eight switches and one filter inductor, the proposed system provides compact and cost-effective circuits in comparison with conventional single-phase individual MPPTs topologies. The proposed system has two split DC-buses from conventional single-phase three-level inverter, thus it is possible that total four DC-link voltages are separately controlled for individual MPPTs. In the control method, proposed system uses two types of voltage controller: DC-bus voltage controller and voltage-difference controller. The formal conducts power distribution and the latter regulates the voltages in each DC-bus. For the voltage-difference controller, offset voltage and switching pattern change methods are presented. Two methods for the proposed system which differs from that of conventional three-level system are analyzed and the proper controllers are designed. In experiments, a prototype circuit is utilized and the feasibility of the proposed method is verified.