Three-level H-bridge flying capacitor converter voltage balance dynamics analysis

Flying capacitor converter is an attractive choice due to its natural voltage balance property. Voltage balance dynamics analytical research methods reported to date are essentially based on a frequency domain analysis. They require high mathematical skills and the solutions are not truly analytical and difficult to use in an everyday practice. In this paper, a straightforward time domain approach based on stitching of consecutive switching intervals analytical solutions is applied to an H-bridge three-level flying capacitor converter. Small parameter analysis yields simple accurate expressions for voltage balance time constants revealing their dependences on load parameters, carrier frequency, and normalized voltage command. Voltage balance dynamics for AC PWM is obtained by averaging DC PWM exponential term decay factors on AC fundamental period.