Effect of Switching Frequency and Floating Capacitor for Five-level Inverter

This paper proposed a strategy on selecting the switching frequency and capacitance value by the requirements of capacitor cost and the different loss under five-level active neutral-point clamped (5L-ANPC) inverter. The effect of switching frequency and capacitance of 5L-ANPC inverter is analyzed in this paper. The loss is related to the switching frequency. When the loss is certain, the switching frequency must fluctuate in a certain range. In order to make the output more easily observed, the capacitance should also be changed when the switching frequency changes. The proposed strategy can effectively control the neutral-point potential (NP) and floating capacitance voltage balancing, and save the cost. The simulation results on a Matlab/Simulink model and prototype of a three-phase 5L-ANPC inverter are used to verify the effectiveness of the proposed control strategy.