Open loop characterization of pulse width modulated DC/DC converters by sequential linear analysis

Pulse width modulated (PWM) DC/DC converters, as typified by the transistor switching regulated (TSR) power supply treated in this paper, can be simulated by modeling each diode and/or switching transistor as a two-valued resistance. In this way, the power supply is represented as a sequence of strictly linear circuits, each having the same topology but with its two-valued resistances determined by the corresponding on-off states of its diodes and transistors. We can compute the startup behavior and periodic response of such power supplies in terms of the eigenvalues and eigenvectors of each of these linear circuits in sequence. What is more, we can also obtain directly the overall state transition matrix from which, in turn, we can predict the open loop characteristics of the entire power supply. This information is vital to the design of feedback networks that provide stable regulation.