Small-Signal Modeling and Dynamic Analysis of a Novel ZVZCS Three-Level Converter

The cyclically switching operation of a novel zero-voltage-zero-current-switching three-level converter is briefly presented. Based on a steady-state time-domain analysis of each equivalent switching topology, an average model is obtained. Small-signal open-loop ac line-to-output, control-to-output, and output-current-to-output-voltage transfer functions are deducted. The stability, gain margin, and phase margin of the open-loop transfer functions are studied. After designing the closed loop, the study of the audiosusceptibility and closed-loop output impedance allows for a dynamic analysis: the transient responses to changes in the input voltage and load current are obtained. The results got from the small-signal modeling are compared and confirmed by those obtained by PSPICE simulation and those measured in the laboratory, on an experimental converter of 4.5 kW