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LQG digital state-feedback control of a Dual-Active-Bridge Series-Resonant Converter

Abstract:

Dual-active-bridge series-resonant converter (DABSRC) is popularly used in low- and medium-voltage applications that demand bidirectional power flow and galvanic isolation. From a discrete-time model of the converter, this paper explores the application of a linear-quadratic Gaussian (LQG) digital state-feedback controller to regulate the output voltage of the DABSRC. The proposed control includes a multivariable servo controller (regulator-integrator loops), a steady-state Kalman filter (SSKF) operating as a full state estimator to avoid increasing the number of sensors and an anti-windup algorithm to avoid the undesirable integrator windup. The SSKF also allows estimating the converter current and the anti-windup algorithm softens the converter start-up. The paper also proposes tuning criteria to facilitate the design of the controller. The results confirm the suitability of this kind of proposal for controlling the DABSRC.