Control method for five level converter with common flying capacitors to avoid voltage level skip

A multilevel converter topology with common flying capacitors (CFC) was proposed recently. It has the advantage that fewer components are required, thus lower cost and higher power density are possible to be realized. However, due to the common circuit shared among different phases, voltage level skips are easy to be caused, which will make the system suffer surge voltage and could be a threat to system insulation. Especially in motor drive application, a costly output filter is always used to protect motor from the impact of voltage level skip. In order to solve this issue and avoid using bulky output filter, this paper proposes a predictive control method for this CFC converter. By using MATLAB/Simulink, it was verified that voltage level skip can be avoided and performance is improved.