A generalized DC model and low-frequency dynamic analysis for theClass-D converter at fixed frequency

摘要

A generalized DC model for constant frequency control of Class-Dnconverters is presented. Based on the Class-D converter with a variablencapacitance switch (VCS), a generalized DC model including some lossesnis found from its steady-state operation waveforms by Fourier analysis.nThe duty ratio of the power switches is retained as an explicitnparameter in the model, which makes the model also useful for pulsenwidth modulation (PWM) control. It is found that VCS control allows anmuch wider range of output voltage variation than PWM control. Moreover,nby small-signal perturbation of the DC model, the AC models for lownfrequency control- and line-to-output responses can also be obtained. Annexperimental Class-D converter with a VCS operating at 350 kHz isnimplemented to verify the derived equations