This paper presents novel switching method and neutral-point voltage control in single-phase 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.
