Parameter and state estimation in power electronic circuits

Techniques for reconstructing or estimating unmeasured circuit variables and parameters in power electronic circuits are investigated. In numerous applications in power electronic systems, measurements of circuit variables are required for closed-loop control purposes or for diagnostic purposes, but are expensive or impossible to obtain directly. The method for state estimation relies on observer theory and is based on an intrinsic Lyapunov function, termed the energy in the increment. For cases where circuit parameters are not completely known, an adaptive estimation algorithm is developed for estimating the unknown circuit parameters along with the unmeasured circuit variables. The exponential stability of the combined parameter and state estimation scheme is established using averaging and singular perturbation analysis. Averaging analysis is used in off-line calculations to determine the feasibility of estimating certain parameters and to determine a basis from which to choose parameter update gains. Examples with an up-down converter illustrate the results. A hardware implementation of the state estimation scheme is also documented along with a description of a hardware implementation for parameter estimation