Controlled-Quantity Concept in Small-Signal Analysis of Switching Power Cells

The notion of a controlled quantity of a switching power cell leads to a set of six (characteristic) coefficients containing all the information on the small-signal, low-frequency behavior of any linearizable cell and defining a universal linear equivalent model of the cell. The result is a dramatic simplification of the small-signal analysis and systematization of the cells. As an illustration, three sets of characteristic coefficients of a boost cell are given: operating in heavy mode and with duty ratio, operating with maximum inductor current, and operating with the period of the switching frequency as the controlled quantity.