Control of simplified multilevel AC-DC-AC converter for small power generation systems

This paper describes control and modulation algorithm of a simplified multilevel AC-DC-AC converter for small power generation system which is based on well known Neutral Point Clamped (NPC) topology. Main advantage of this approach allows single 3-phase, 3-level converter to be utilized as a full interface between Permanent Magnet Synchronous Generator (PMSG) and the single-phase grid. Study of control and modulation for simplified converter are supported by simulation and experimental results. The three-phase AC-DC converter is controlled with regard of Field Oriented Control (FOC) principle. The current control of the single-phase DC-AC converter is based on the P+Multi-Resonant controller and Second Order Generalized Integrator Phase Locked Loop (SOGI-PLL). The multi resonant structure in single-phase converter allows a proper operation under non-ideal grid voltage.