Transient modelling and simulation of parallel resonant converters

Open-loop transfer functions of parallel resonant converters (PRCs) as well as the transfer function of the feedback loop are derived. Three types of PRCs are considered (the ideal case neglecting the effect of the HF transformer, the case including the effect of the HF transformer, and the case with a resonating capacitor on the secondary-side of the HF transformer). The system response for step changes in the reference signal, input supply, load resistance, and VCO frequency was studied on a Sun workstation, using PROMATLAB and IG-SPICE. The effects of controllers on the performance of the PRCs are also studied. It is shown that the value of the output filter capacitor influences the current transients through the resonating inductor and the voltage transients across the resonating capacitor. Discontinuities in the resonating capacitor voltage during transients are observed. Some of the theoretical predictions were experimentally verified on PRCs built with and without the feedback control loop.<>