Abstract
In the field such as various electric power compensator and ac motor drives, large capacity and high-performance converter are wished to be put into practical applications, with development of various technologies. For these converters, since the upper limit of the switching frequency is low and capacity of device is insufficient, method of connecting the device in series and parallel would be effective. From such reasons, for improving the harmonic characteristics, various multi-level inverters have been reported, in which it is necessary to provide some dc power supplies connected in series that is disadvantage for this inverter. We propose a simple dc-dc converter for adjusting power supply voltage of this inverter. The system is very easy to use because the conventional circuit control techniques can be applied without difficulty. By means of this dc-dc converter circuit, the voltage of four dc power supplies of five-level inverter can be suitably controlled towards the desired value. The circuit characteristics are discussed by theoretical and simulated procedures. The theoretical results and the experimental ones are agree with each other.
