Real time implementation of an adaptive backstepping control of buck converter PMDC-motor combinations

Abstract

This article presents an experimental realization of adaptive backstepping control methodology on a cascaded buck converter permanent magnet dc (PMDC)-motor combination for angular velocity control. The experiment aims at illustrating the practical applicability of adaptive control to power converters fed with a DC motor load. The systematic design procedure of conventional backstepping control design is enhanced by incorporating an online adaptive control mechanism to estimate the unknown non-linear load torque. Asymptotic stability of the closed loop system under the action of proposed control law is ensured and update law is derived satisfying Lyapunov stability criterion. The experimental investigation is conducted using dSPACE, Control Desk DS1103 setup with an embedded TM320F240 Digital Signal Processor. The buck dc-dc converter fed PMDC motor system is subjected to a wide variation in load torque and set point angular velocity tracking. The results obtained through adaptive backstepping control scheme have been evaluated against the conventional backstepping control mechanism. Results highlight a superior performance using adaptive backstepping control by producing an accurate and time bound estimation of unknown load torque, under both nominal and perturbed conditions, thereby improving the transient and steady state response of desired angular velocity.