PUBLICATIONS

This paper presents novel switching method and neutral-point voltage control in singlephase three-level NPC (neutral-point clamped)

inverter. Recently, the three-level NPC inverter is widely used in PV (photovoltaic) systems. Therefore, the efficiency has become an

important factor. To improve the efficiency, this paper proposes two methods. The first propose is a novel switching method, the

concept of which is to fix the switching state of one-leg in the single-phase three-level NPC inverter. As a result, the switching loss

is reduced in the single-phase three-level NPC inverter. The second propose is a neutral-point voltage control to improve the MPPT

(Maximum Power Point Tracking) operation. The second proposed method is implemented by changing small vectors and modifying

the reference signal. Computer simulation and experimental results are provided to verify the performance of the control scheme.