Generalisation of flying capacitor-based active-neutralpoint- clamped multilevel converter using voltage-level modulation

A generalised n-level flying capacitor (FC)-based active-neutral-point-clamped (ANPC) voltage source converter is discussed in this study. The converter is based on the arrangement of a three-level ANPC cell and a number of two-level cells creating an n-level line-to-neutral voltage waveform. The converter is operated under a phase-shifted carrier (PSC) pulse-width modulation (PWM) technique. The mathematical model for the DC-link capacitors´ voltage behaviour of the three-phase converter is also presented. It is shown through simulations that the voltage of the FCs can naturally balance to the required level to generate the required waveforms. Selected results are included in the study to support the analysis. Moreover, experimental results taken from a single-phase seven-level FC-based ANPC converter prototype are also presented to verify the theoretical considerations.