Symbolic analysis of switched-mode DC-to-DC converters

A method of modeling PWM switches for symbolic analysis of pulse-width-modulated (PWM) dc-to-dc converters operating in the continuous conducting mode (CCM) is described for switches with both fixed and modulated duty ratio. The well-known average models of PWM switch according to Vorperian are implemented by means of modified nodal analysis into the SNAP program to analyze transfer and immittance functions, especially the line-to-output and control-to-output transfer functions in the symbolic and semisymbolic forms, and the corresponding frequency responses. An example of the analysis of boost converter is shown.