Nonlinear modelling of the PWM switch

It is shown that nonlinearity due to the switching action in pulse width-modulated (PWM) DC-to-DC converters, DC-to-AC inverters or amplifiers, and input-current-shaping DC-to-DC converters can often conveniently be confined to a three-terminal structure referred to as the PWM switch. the PWM switch represents a static nonlinearity for which circuit models can easily be derived for frequencies harmonically related to the frequency of perturbation. Converter analysis can now be approached in an analogous way to ordinary transistor circuit analysis whereby the nonlinear three-terminal device is replaced by its circuit model. A first-order approximation of the model results in the small-signal model.<>