Generalized modulator for the seven-level flying capacitor based active neutral point clamped converter

The flying capacitor (FC) based active neutral point clamped (ANPC) converter is a hybrid multilevel converter topology, as a combination of the three-level ANPC converter and a number of FC cells. This paper presents a generalized modulator for the seven-level FC based ANPC converter. The proposed modulator is applied independently in each phase of the converter and selects the switching states based on the deviation of the FC voltages from the reference value in order to maintain the FCs and the neutral point voltage of the converter balanced. The modulator is independent of the modulation technique selected for the converter and can operate under both sinusoidal and selective harmonic elimination pulse width modulation. Simulation results for both modulation techniques indicate the operation of the converter while regulating the FC and NP voltages to their references under steady state and dynamic changes and illustrate its effectiveness.