Optimal control approaches to switching power converters

Minimization of a specified cost function is a standard approach to optimal control that unifies large-signal and small-signal performance. Here, quadratic output-error cost functions are considered for power converters. The conventional form of quadratic function is intractable for many converters. Several cost functions which approximate it, but are easier to apply, are introduced. Examples include a cycle-by-cycle quadratic function, a cost function based on the stored energy in a converter, and fast-switching approximations to quadratic functions. These functions are studied for dynamic performance and stability. Results are shown to provide good performance, with little distinction between large and small disturbances