Generalization of the injected-absorbed-current dynamic analysis method of DC-DC switching power cells

The authors show that a conceptually simple, general, and systematic analysis approach can be used to obtain a low-frequency model for any switching cell. The injected-absorbed-current dynamic analysis approach can be used with topologies with any number of state variables. General expressions for all six characteristic coefficients, defining the linearized model, are derived. Partial derivations of the absorbed and injected currents and of the state variables in these coefficients were determined numerically from the perturbed steady-state relations. In this way, the calculations were substantially reduced. Using the numerical model of the cell, linear analysis of the entire regulator, including the input and the output filters, can be carried out. The generalization yields an acceptably accurate model which is independent of the cell topology, control method and operating mode. The application of the method was demonstrated on a series resonant converter