Nonlinear modeling of pulsewidth-modulated and quasi-resonant converters

Analytical modeling of pulse width modulated (PWM) and quasi-resonant power converters to account for their nonlinear responses due to both multitone line input and control signal is presented. The key is to extend the Volterra functional analysis to nonlinear systems with multiple independent inputs. By formulating state-space equations describing the dynamical behavior of converter circuits, the nth-order transfer functions of these nonlinear circuits can be determined by explicit and recursive formulae. Thus, the output response is the summation of the corresponding nth-order responses, which consists of various higher harmonic and intermodulation frequency components. The modeling approach has been exemplified for the PWM boost converter and zero current switching quasi-resonant buck converter operating in full-wave mode