A State Observer for Sensorless Control of Power Converters With Unknown Load Conductance

In this article, the sensorless control problem of a large class of power converters with unknown load conductance is investigated. A reduced-order generalized parameter estimation-based observer (GPEBO) is presented to reconstruct the unmeasurable states and estimate the unknown load conductance of the system. Three nice features of this observer are as follows: finite-time convergence (FTC) is guaranteed, an alertness preservation is imposed to be able to estimate a possibly time-varying load, and the required excitation condition is very weak and can be satisfied in normal operation of power converters. Then, replacing the estimated states and parameter, in a certainty equivalent manner, in a PI passivity-based controller, a sensorless control scheme is proposed to stabilize the systems with exponential convergence. By virtue of the FTC property of the GPEBO, the global exponential stability of the overall closed-loop system is established. Simulation and experimental results of the proposed controller with application to the boost and Ćuk converters are given to assess its effectiveness.