Parameters design evaluation in 3-level flying capacitor boost converter

Flying capacitor boost converter (FCBC) is one of the possible power converter for high power applications such as solar systems and electric vehicles system and so on. The aim of this paper is to establish relationship between the capacitance of the flying capacitor and output voltage ripple. 3-level FCBC prototype has been constructed for parameters design confirmation. Experimental result shows that the input current ripple is within design value. By identifying the input current ripple, the inductance of the boost inductor is estimated and it needs approximately only 25% compared to the 2-level conventional boost converter. Besides, 3-level FCBC only requires inductor core volume of 35% compared to the 2-level conventional boost converter. Moreover, it is confirmed that the relationship between the capacitance of the flying capacitor and output voltage ripple is independent. This finding is concretely proven by the simulation and experimental results. Therefore, the boost inductor and capacitance of the flying capacitor can be designed independently without considering output voltage ripple.