# Automatic Control of Converter-Fed Drives

This book introduces the reader in a systematical way to the design philosophy behind vector control systems. The mathematical motor models based on complex-space vector descriptions as well as the control structures for DC motors provide a perfect basis for explaining the principles of AC motor vector control. An in-depth review of electromagnetic transients in induction motors under various methods of frequency control is given. This is explained with the help of appropriate block schemes and new equivalent circuits. Properties of AC motors under non-sinusoidal supply are reviewed. The basic power converter topologies applied in motor control technology as well as symmetry and loss reduction problems are discussed. Some examples of controller design methods are presented step by step. An important feature of the book is that it contains many examples of systems applied in practical engineering as well as simulation and experimental results. The volume will be of interest to all those familiar with the basics of electrical machines and control systems theory. Therefore, it is recommended to students of electrical, electronics and mechanics departments. The book can also be used by those working in industry, who are interested in modern power electronics, drives and motion control, robotics as well as automation of industrial processes.

Hardbound,

Published: April 1994

Imprint: Elsevier

ISBN: 978-0-444-98660-3

## Contents

• 1. Mathematical Models of Electrical Motors. Introduction. Voltage and flux-current equations. Space vectors and their representation in coordinate systems. Voltage and flux-current equations written in terms of space vectors. Transformation of vector equations into common rotating coordinate systems. Referring rotor quantities to the stator circuit. Instantaneous power and electromagnetic torque. Mechanical motion equation. Complete set of equilibrium equations. Park's transformation. Relationship between equations based on complex space vectors and the unified theory of electrical machines. Linearization of equilibrium equations. State equations and transfer functions. Per unit system. 2. Three-Phase Induction Motor. Design and basic types. Vector equilibrium equations in per unit system. Block diagrams. State equations. Properties of induction motors in steady states. Speed control by changing the supply frequency. 3. Three-Phase ac Synchronous Motors. Designs and major types. Equilibrium equations in per unit system. Block diagrams. Properties of synchronous motors in steady states. Speed control. 4. Separately Excited dc Motors. Design and major parameters. Equilibrium equations and equivalent circuits. Block diagrams and operator transfer functions. Steady-state characteristics. Speed control methods. 5. Power Converters for Motor Control. Line-commutated rectifiers and inverters. Frequency changes. Current-sourced inverters. Voltage-sourced inverters. Voltage-sourced dc-to-dc converters. Minimization of the losses of high-frequency power electronic switches. 6. Principles of Control System Synthesis. Dynamic optimization of continuous-time closed-loop systems. Digital control systems. Adaptive control systems. 7. Control Systems for DC Motor Drives. Dynamic properties of speed control systems. Dc drive with line-commutated converter. Dc drive with dc-to-dc converter. Digital analogue speed control systems. Adaptive speed control system. 8. Control Systems for the Wound Rotor Induction Motors. Speed control by: supply voltage variation; varying rotor circuit resistance. Double-fed induction motor. 9. Frequency-Controlled Induction Motor Drive Systems. Conditions of static optimization of control. Induction motor operation with non-sinusoidal supply wave-forms. Dynamic behaviour of frequency converter-fed induction motor under different modes of control. CSI-fed drive systems. Current-controlled PWM inverter-fed drive systems. VSI-fed induction motor drives. 10. Frequency-Controlled Synchronous Motor Drive Systems. Optimization conditions under steady states. Open-loop and self-controlled operation. Cycloconverter-fed drive systems. Load-commutated CSI-fed drive systems. Transistor PWM inverter-fed PM synchronous motor drive systems. Voltage/frequency control of VSI-fed multiple motor drives. 11. Introduction to Microprocessor Control. Appendices. References. Symbols employed. Index.