  Models that accurately predict the output voltage ripple magnitude are
essential for applications with stringent performance target for it. Impact of
dc input ripple on the output ripple for a Series Resonant Converter (SRC)
using discrete domain exact discretization modelling method is analysed in this
paper. A novel discrete state space model along with a small signal model for
SRC considering 3 state variables is presented. The audiosusceptibility (AS)
transfer function which relates the input to output ripple is derived from the
small signal model. Analysis of the AS transfer function indicates a resonance
peak and an expression is derived connecting the AS resonance frequency for
input ripple with different SRC component values. Further analysis is done to
show that a set of values for SRC parameter exists, which forms a design
region, for which the normalized gain offered by the SRC for input ripple is
less than unity at any input ripple frequency. A test setup to introduce the
variable frequency ripple at the input of SRC for the experimental evaluation
of AS transfer function is also proposed. Influence of stray parameters on AS
gain, AS resonance frequency and on SRC tank resonance frequency is addressed.
An SRC is designed at a power level of 10kW. The analysis using the derived
model, simulations, and experimental results are found to be closely matching.
