Mechanical Parameter Estimation of Three Phase Induction Motor using VFD

Abstract

When a motor drive system is in operating condition, variation in load and machine vibrations will affect the control system performance. Estimation of Moment of inertia becomes essential to improve the dynamic response characteristics of any high-performance Asynchronous Machine (ASM) drive system. Model Reference Adaptive System (MRAS) is an adaptive control method used by a controller which must adapt to a controlled system with parameters which vary, or are initially uncertain. The benefit of using adaptive control over robust control is that it does not need a priori information about the uncertain or time-varying parameters. Robust control guarantees that if the changes are with in given bounds the control law need not be changed, while adaptive control is concerned with control law changing itself. A novel method using Model Reference Adaptive System (MRAS) with Error Utilization Technique (EUT) for precise online inertia identification is presented in this thesis. The proposed method uses an interesting relation between the estimation error and actual inertia, to compensate for the error and provide high precision online inertia identification.