This paper presents a review of recently used direct torque and flux control (DTC) techniques for voltage inverter-fed induction and permanent-magnet synchronous motors. A variety of techniques, different in concept, are described as follows: switching-table-based hysteresis DTC, direct self control, constant-switching-frequency DTC with space-vector modulation (DTC-SVM). Also, trends in the DTC-SVM techniques based on neuro-fuzzy logic controllers are presented. Some oscillograms that illustrate properties of the presented techniques are shown.

Direct torque control of PWM inverter-fed AC motors - a survey

Field-oriented control and direct torque control are becoming the industrial standards for induction motors torque control. This paper is aimed at giving a contribution for a detailed comparison between the two control techniques, emphasizing advantages and disadvantages. The performance of the two control schemes is evaluated in terms of torque and current ripple, and transient response to step variations of the torque command. The analysis has been carried out on the basis of the results obtained by numerical simulations, where secondary effects introduced by hardware implementation are not present.

FOC and DTC: two viable schemes for induction motors torque control

A direct induction machine torque control method based on predictive, deadbeat control of the torque and flux is presented. By estimating the synchronous speed and the voltage behind the transient reactance, the change in torque and flux over the switching period is calculated. The stator voltage required to cause the torque and flux to be equal to their respective reference values is calculated. Space vector PWM is used to define the inverter switching state. An alternative approach to deadbeat control for use in the transient or pulse-dropping mode is also presented. An alternative modulation scheme is presented in which transient performance is improved by specifying the inverter switching states and then calculating the required switched instants to maintain deadbeat control of the flux while reducing the torque error during the entire switching interval. A similar approach is used for a transient in the flux. The implementation of the control scheme using DSP-based hardware is described, with complete experimental results given. >

Direct torque control of induction machines using space vector modulation

Permanent magnet (PM) brushless machines having magnets and windings in stator (the so-called stator-PM machines) have attracted more and more attention in the past decade due to its definite advantages of robust structure, high power density, high efficiency, etc. In this paper, an overview of the stator-PM machine is presented, with particular emphasis on concepts, operation principles, machine topologies, electromagnetic performance, and control strategies. Both brushless ac and dc operation modes are described. The key features of the machines, including the merits and drawbacks of the machines, are summarized. Moreover, the latest development of the machines is also discussed.

Overview of Stator-Permanent Magnet Brushless Machines

In the present paper, the internal model control (IMC) method is introduced and applied to AC machine current control. A permanent magnet synchronous machine is used as an example. It is shown that the IMC design is straightforward and the resulting controller is simple to implement. The controller parameters are expressed in the machine parameters and the desired closed-loop rise time. The extra cost of implementation compared to PI control is negligible. It is further shown that IMC is able to outperform PI control with as well as without decoupling with respect to dq variable interaction in the presence of parameter deviations.

Model-based current control of AC machines using the internal model control method

Induction Machines in the Industry. Topology and Operation of Induction Machines Materials and Losses. Windings and their mmfs. No-Load Field Distribution. Equivalent Circuit Parameters. Steady-State Performance Calculations. On-Load Saturation and Frequency Effects on Circuit Parameters. Skewing and Inter-Bar Rotor Currents. Space Harmonics in Airgap Field. Core and Winding Fundamental and Harmonic Losses. Thermal Modeling. Space Phasor Models for Transients and Variable-Speed Operation. Design Specifications. Preoptimization Design Methods and Case Studies. Design Optimization Methods. Design Optimization Case Studies for Constant Frequency Operation. Design Optimization Case Studies for Variable Frequency Variable Speed Operation. Design of Induction Generators. Design of High-Speed Induction Motors Linear Induction Motors. Ultra-High Frequency Effects of Power Electronics Tests on Induction Machines. Induction Motor Monitoring. Single-Phase Induction Motors.

The Induction Machine Handbook

Linear electric actuators and generators (LEAGs) are electromagnetic devices which develop directly short-travel progressive (or oscillatory) linear motion. Machine tool sliding tables, pen recorders and free piston power machines are typical industrial applications for LEAGs. Their recent revival in applications in compressors, pumps, electromagnetic valve actuators, active shock absorbers, vibrators, etc. Prompts this review, which presents main LEAGs configurations, their principles of operations, comparative performance evaluation, motion control and existing as well as potential applications.

Linear Electric Actuators and Generators

INTRODUCTION. Electric Drives Topology. Motor-Load Dynamics and Stability. Typical Load Torques. Multiquadrant Operation. Converters for AC Motors. Performance Indices of Modern Electric Drives. Vector Controllers. Control Robustness. Vector Control of AC Drives. AC MOTOR MODELS FOR DRIVE APPLICATIONS. The Phase Variable Model of Induction Machines. Complex Variable (Space Phasor) Model of Induction Machines. The dq Model of Induction Machines. Treatment of Saturation. The Phase Variable Model of Synchronous Machines. The Complex Variable (Space Phasor) Model of Synchronous Machines. Complex Variable (Space Phasor) Diagram of the Synchronous Motor. FUNDAMENTALS OF INDUCTION MACHINE VECTOR CONTROL. The General Flux Orientation Concept. Vector Current Control. Vector Voltage Control. Constant Airgap Flux Operation. Constant Rotor Flux Operation. Constant Stator Flux Operation. Constant Flux Operation Comparisons. VECTOR CONTROL OF VOLTAGE-SOURCE INVERTER-FED INDUCTION MOTOR DRIVES. Indirect Rotor Flux Orientation-Vector Current Control. Indirect Rotor Flux Orientation-Vector Voltage Control. Robust Flux Estimation for Direct Vector Control. Airgap Flux Orientation-Vector Current Control. Direct Slater Flux Orientation-Vector Control. Torque Vector Control (TVC). VECTOR CONTROL OF CURRENT-SOURCE INVERTER-FED INDUCTION MOTOR DRIVES. Indirect Rotor Flux Orientation Vector Control. Torque Vector Control (TVC). FUNDAMENTALS OF SYNCHRONOUS MACHINE VECTOR CONTROL. The Equations with the Stator Flux Evidentiated. Variable g* Control (i*d = Constant or d-q Control). Constant g* (Power Factor Angle) Control. Voltage Vector Control. Torque Vector Control. Steady State Operation for Given i*d. Steady State Operation for Given Stator Flux ls* and Constant g*. VECTOR CONTROL OF PERMANENT-MAGNET SYNCHRONOUS MOTOR DRIVES. Indirect Vector d-q Current Control. Indirect Vector Voltage Control. Torque Vector Control. VECTOR CONTROL OF VOLTAGE-SOURCE INVERTED-FED RELUCTANCE SYNCHRONOUS MOTOR DRIVES. Saliency Ratios with Axially-Laminated Anisotropic (ALA) Rotor. Torque, Power Factor, Losses. Current dq Angle Vector Control. Torque Vector Control. VECTOR CONTROL OF CYCLOCONVERTER-FED SYNCHRONOUS MOTOR DRIVES. Stator Flux Orientation-Vector Current Control. Stator Flux-Orientated Control Equations. The Current Controller. The Flux Calculator. The Current Reference Calculator and Flux Controller. Torque Vector Control. VECTOR CONTROL OF CURRENT-SOURCE INVERTER-FED SYNCHRONOUS MOTOR DRIVES. Indirect Simplified Vector Current Control. Steady State Operation with Load Commutation. Commutation and Steady State Equations. Ideal No-Load Speed. Steady State Characteristics. Line Commutation During Starting. Dynamics and Control. Digital Simulation and Test Results. Torque Vector Control.

Vector control of AC drives

Vector analysis electrostatic fields magnetostatic fields Maxwell's equations propagation of uniform plane waves transmission lines waveguides and cavity resonators antennas appendices - derivation of Ampere's law, Faradays law for moving charges, the smith chart, physical constants, materiial properties, and other useful data.

Syed A. Nasar

Papers

The Induction Machine Handbook

Linear Electric Actuators and Generators

Vector control of AC drives

Introduction to electromagnetic fields

Linear motion electric machines