Direct torque control - or DTC - is the most advanced AC drive technology developed by any manufacturer in the world. The purpose of this technical guide is to explain what is; why and how it has evolved; the basic theory behind its.
Electric motors are widely used in industries to convert electrical energy into mechanical form. Control techniques are designed to improve the performance and efficiency of the drive so that large amounts of electrical energy can be saved. This book is primarily written with the objective of providing necessary information on use of electric motors for various applications in industries.
This chapter introduces two-inductance, T and T', per-phase equivalent circuits of the induction motor for explanation of the scalar control meth-ods. The open-loop, Constant Volts Hertz, and closed-loop speed control methods are presented, and field weakening and compensation of sup and stator voltage drop are explained. Finally, scalar torque control, based on decomposition of the stator current into the flux-producing and torque-producing components, is described.
Control methods for high-performance ASDs with induction motors by direct selection of consecutive states of the inverter are presented in this chapter. The direct torque control (DTC) and Direct Self-Control (DSC) techniques are explained, and we describe an enhanced version of the DTC scheme, employing the space-vector pulse width modulation in the steady state of the drive.
Modern electrical drive systems are composed principally of; motors, power electronics
components, transformers, analog/digital controllers and sensors or observers. The
improvements and the enormous advances in the fi eld of power electronic (semiconductor
components), converters technology and soft ware/implementation technology
have enabled advanced and complex control techniques. With these advances and robust
control algorithms improved, considerable research eff ort is devoted for developing
optimal techniques of speed and torque control for induction machines....