High‐dynamic AC machine control without speed or position sensor

Abstract

In many applications inverter-fed 1 .S machines with high dynamic performance are needed, but position control is not required. Conventionalfield-oriented control fulfils the dynamic requirements, but usually needs a costly position or speed sensor: Simple voltage-frequency control avoids these sensors, but will only achieve a moderate dynamic performance. For such applications a self controlled scheme based on the measured flux vector may be used. In this paper a flux phase control loop and a method of backing the flux model with an observer to improve the behaviour at low stator frequencies are described.