Modelling and Control of a Flying-Capacitor Inverter S. J. Watkins EPE 2001 – Graz P. 1 Modelling and Control of a Flying-Capacitor Inverter

This paper presents the results of an investigation into the variation in the output voltage quality of a flying-capacitor inverter under staircase angle control. The trade-offs between capacitor size, power device voltage rating and output voltage quality are assessed through simulation. A general mathematical model for an N-level inverter is used for circuit operation analysis and its results are compared with those from a Simulink circuit simulation. The computer model allows a thorough investigation of all possible switching pattern permutations that produce the desired sinusoidal output and maintain steady state capacitor voltage balancing. Results show that the total harmonic distortion in a sinusoidal synthesised output can be minimised by the correct selection of the switching mode sequence. Keywords: multilevel converters, modelling, power quality, harmonic