A New Modulation Scheme for a Four-Level Single Flying Capacitor Converter

This article proposes a four-level single flying capacitor converter (4L-SFCC) topology along with a new modulation technique. The proposed four-level single flying capacitor converter (4L-SFCC) topology has only one flying capacitor in each phase. This results in no redundant switching states associated with each voltage levels, and thus conventional modulation techniques cannot fulfill the capacitor voltage balancing requirement. Therefore, a new modulation technique is also proposed in this article in which the average capacitor current is set to zero during each sampling time, resulting in no net capacitor voltage change and hence voltage balancing during each sampling period. The proposed modulation scheme does not significantly increase the switching frequency and has equal switching frequency for all semiconductor switches, which is an advantage in terms of equalized switching losses. Simulation results are used to further evaluate the performance of the proposed converter. A laboratory-type experimental setup is used to validate the theoretical results.