Spectral Modeling of Switched-Mode Power Converters in Discontinuous Conduction Mode

Analytical spectral modeling of switched-mode PWM converters, operating in the discontinuous conduction mode, is presented. The modeling approach is to derive analytical expressions of the converter output response using the extended Volterra functional series. Nonlinear frequency responses, including additional DC offset as well as significant subharmonic and higher harmonic components, due to large-signal perturbations of both the duty ratio and source voltage, are investigated. Their vulnerability to switching frequencies are also described. This modeling approach has been applied to various PWM converters, boost, buck and buck-boost types, operating in the discontinuous conduction mode, and the results are verified.