2014 Volume 134 Issue 10 Pages 904-912
In this study, a novel approach to realizing low-voltage distortion with a new multilevel inverter is presented. The inverter targets systems with rechargeable batteries. The advantage of the proposed single-phase 7-level inverter is that the line-line voltage of seven steps can be outputted and the voltage distortion can be reduced. This paper presents the control method. The experimental results show that the voltage THD of the proposed 7-level inverter becomes 18.2% when the voltage reference is the same as the DC-link voltage, and is smaller than that of the conventional 2-level and 3-level inverters. Furthermore, at the same voltage reference, the simulation results show that (i) the difference between each electric charge supplied by each cell battery in the asymmetrical DC voltage sources is less than 20% and (ii) the switching loss of the U-phase switching devices in the proposed inverter is only 1/10 that of the 2-level inverter and 1/3 that of the 3-level inverter.