Parallel resonant converter as a circuit simulation primitive

Abstract

The paper presents a SPICE macromodel for a generic parallel resonant converter circuit. The model is derived from the averaged time-invariant state-space equations obtained from Fourier transform. The conditions are derived under which all but the fundamental harmonic may be discarded, and the model developed based solely on the fundamental Fourier component. The single macromodel developed has a wide range of validity, allowing DC, AC and transient analyses to be carried out using the entire converter as a circuit primitive. Thus, such a converter may be incorporated (alongside its control circuitry), as a primitive, into an entire system. Example analyses show a parallel resonant circuit, embedded in a feedback loop, becoming unstable when the load undergoes a step change. A similar set of analyses, carried out at component level, yield identical results, but require runtimes greater by a factor of between 192 and 6600. Finally, the 'stability region' of the circuit, characterised by the load resistance, is calculated. This kind of information is extremely useful to the designer, and not usually easily obtained.