Vector Control and Dynamics of AC Drives

Electric drive systems is an area of great change and increasing commercial importance in industry today. Written by experts in the field, this book takes account of recent developments. These have been due largely to the advances in power electronics and computer control; in turn, they have made possible the implementation of a.c. drive systems, in place of d.c. Topics include inverter machine dynamics; constant speed behavior and the development of conventional equivalent circuits; vector controlled systems; and current regulators.

This book presents a detailed but easily understood development of the complex variable form of the equations describing AC machines. These equations are then extended to incorporate inverter models and a number of examples of inverter-machine dynamics are presented. A section on constant speed behaviour includes development of the conventional equivalent circuits and an extensive treatment of the constant speed eigenvalues and switching transients. Vector control and field orientation concepts are first introduced in terms of their steady state properties. This allows anyone with a basic understanding of steady state machine behaviour to understand and appreciate the potential of field orientation and to actually start using the book immediately. This is followed by a full dynamic analysis of vector controlled systems including conventional indirect and direct field orientation and less conventional systems that orient to air gap or stator flux rather than rotor flux. A chapter on the important types of current regulators is also included. The final two chapters deal with vector control and field orientation system performance in relation to tuning errors, saturation effects, selection of flux levels to optimize performance and the question of optimization in the field weakening mode.

1 - Introduction to AC drives
2 - d-q modelling of induction and synchronous machines
3 - d-q models for solid state power converters
4 - Complex vector analysis of induction machines
5 - Principles of vector control and field orientation
6 - Dynamics of vector control and field orientation
7 - Current regulation in power converters
8 - Parameter sensitivity and saturation effects in indirect field orientation
9 - Field weakening operation