A General Approach to Sampled-Data Modeling for Power Electronic Circuits

A general sampled-data representation of the dynamics of arbitrary power electronic circuits is proposed to unify existing approaches. It leads, via compact and powerful notation, to disciplined modeling and straightforward derivation of small-signal models that describe perturbations about a nominal cyclic steady state. Its usefulness is further illustrated by considering the representation and analysis of a class of symmetries in circuit operation. The results of the application of this methodology to modeling the small-signal dynamics of a series resonant converter are described. The results correlate well with simulation results obtained on the Massachusetts Institute of Technology's Parity Simulator. What is of greater significance is the fact that the small-signal model is obtained in a completely routine way, starting from a general formulation and working down to the actual circuit; this contrasts with the circuit-specific analyses that are more typical of the power electronics literature. The automatability of this procedure is also discussed, and it is pointed out that the key ingredients for automatic generation of dynamic models from a circuit specification are now available.