An Active Capacitor Voltage Balancing Method for a Four-Level Single Flying Capacitor Converter

The four-level single flying capacitor converter (4L-SFC) is an efficient topology for medium-voltage applications, offering a reduced component count over traditional four-level flying capacitor converters. However, maintaining balanced capacitor voltages is a key challenge in this topology, which is critical for stable and reliable operation. In this paper, an active voltage balancing method for 4L-SFC converters is presented, using a straightforward algorithm to adjust voltage levels in response to real-time measurements of capacitor voltages and phase currents. As a result of the proposed method, capacitor voltages remain balanced across a wide range of modulation indexes and operating conditions without significantly increasing switching frequency. Simulation results have demonstrated the effectiveness of the proposed approach, demonstrating that it is capable of maintaining stable capacitor voltages.