Now a day’s induction motor drives are highly demanding to design both mechanical and electrical drive system which is used widely in many industrial applications. Recent years many mathematical models for induction motor drive using Simulink models are employed. Scalar and Vector control method can be applied to induction motors in three phases symmetric as well as unsymmetrical two-phase form. The mathematical and Simulink operation of the induction motor drive can be studied and it is equivalent to a DC motor by the vector control method. With the combined performance of the numerical electronics and power electronics we are capable to smoothly control the variable speed and torque in low power industrial operations. With the help of technological achievements, several command and control techniques are developed by the technologists to control the time, flux and torque of the industrial electrical machine drives. The direct torque control (DTC) technique is one of the most advanced mechanisms in control operation of torque and speed. This technique with SVPWM gives fine regulation without rotational speed controlled feedback. The electromagnetic torque and stator flux are estimated in DTC technique only stator currents and voltage and it is independent of the parameters of the motor except for the Rs i.e. stator resistance .
- SVPWM and switching table.
Fig.1. DTC block diagram
EXPECTED SIMULATION RESULTS:
Fig.2. Electromagnetic torque
Fig.3. Rotor speed
Fig.4. Stator current
Fig.5. d-axis stator flux
Fig.6. q-axis stator flux
Fig.7. Electromagnetic torque
Fig.8. Rotor speed
Fig.9. Trajectory of direct axis stator and quadrature axis
flux (stationary reference frame)
Fig.10. Electromagnetic torque
Fig.11. Rotor speed
Fig.12. Direct axis stator flux
Fig.13. Quadrature axis stator flux
Fig.14. Direct axis stator current
Fig.15. Quadrature axis stator current
Fig.16. Stator flux trajectory
Fig.17. Rotor flux trajectory
The proposed paper highlights to create a Simulink model of DTC in induction motor drive. The DTC technique allows the decoupled control of torque and stator flux operate indipendently. The control process is simulated with the help of simpower system MATLAB Simulink block set and Sector determination with open-loop induction motor drive is obtained. In conventional DTC technique, high torque ripple is produced because the voltage space vector which are considered is applied for the whole switching period without considering the torque error value. This torque ripple can be minimized in order to achieve a smooth operation of the drive system and its performances, by changing the duty cycle ratio of the voltage vector which are selected during each switching cycle period, based on the stator flux position and torque error magnitude. This constitutes the basic of SVPWM technique. here simulate DTC scheme based on SVPWM technique and comparative study of conventional DTC-SVM scheme is derived and studied.
 Takahashi Isao, Noguchi Toshihiko, ,,’’A New Quick-Response IEEE Transactions on Industry Applications , Vol. IA-22No-5, Sept/Oct 1986.