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

A generalized DC model for constant frequency control of Class-D converters is presented. Based on the Class-D converter with a variable capacitance switch (VCS), a generalized DC model including some nonlinearities is found from its steady-state operation waveforms by Fourier analysis. The duty ratio of the power switches is retained as an explicit parameter in the model. Moreover, by small-signal perturbation of the DC model, the ac models for low frequency control- and line-to-output responses can also be obtained. An experimental Class-D converter with a VCS operating at 350kHz is implemented to verify the derived equations.