PARAMETER AND STATE ESTIMATION IN POWER ELECTRONIC-CIRCUITS

Techniques for reconstructing or estimating unmeasured circuit variabl es and parameters in power electronic circuits are investigated. In nu merous applications in power electronic systems,measurements of circui t variables are required for closed-loop control purposes or for diagn ostic purposes, but are expensive or impossible to obtain directly. Ex amples are certain inductor currents, voltages at high impedance nodes where probes cannot be applied, or circuit variables in electrically isolated portions of a circuit, The method for state estimation relies on observer theory and is based on an intrinsic Lyapunov function, te rmed the energy in the increment. For cases where circuit parameters a re not completely known, an adaptive estimation algorithm is developed for estimating the unknown circuit parameters along with the unmeasur ed circuit variables. The exponential stability of the combined parame ter and state estimation scheme is established using averaging and sin gular perturbation analysis. Averaging analysis is used in offline cal culations to determine the feasibility of estimating certain parameter s and to determine a basis from which to choose parameter update gains . Examples with an up-down converter illustrate the results. A hardwar e implementation of the state estimation scheme is also documented alo ng with a description of a hardware implementation for parameter estim ation.