ABSTRACT:
This paper describes a combination of direct torque
control (DTC) and space vector modulation (SVM) for an adjustable speed sensorless
induction motor (IM) drive. The motor drive is supplied by a two-level SVPWM
inverter. The inverter reference voltage is obtained based on input-output
feedback linearization control, using the IM model in the stator – axes
reference frame with stator current and flux vectors components as state
variables. Moreover, a robust full-order adaptive stator flux observer is
designed for a speed sensorless DTC-SVM system and a new speed-adaptive law is
given. By designing the observer gain matrix based on state feedback control theory, the stability and robustness of the
observer systems is ensured. Finally, the effectiveness and validity of the
proposed control approach is verified by simulation results.
KEYWORDS:
1.
Adaptive
stator flux observer
2.
Direct torque control
3.
Feedback linearization
4.
Robust
5.
Space vector
modulation
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig.
1.The block diagram of the DTC-SVM system
CONCLUSION:
A novel DTC-SVM scheme has been developed for
the IM drive system, which is on the basis of
input-output linearization control. In
this control method, a SVPWM inverter is used to feed the
motor, the stator voltage vector is obtained to fully compensate the stator flux and torque errors.
Furthermore, a robust full-order
adaptive flux observer is designed for a speed sensorless DTC-SVM system. The stator flux and speed are
estimated synchronously. By designing the constant
observer gain matrix based on
state feedback H∞ control theory, the
robustness and stability
of the observer systems is ensured. Therefore, the proposed sensorless drive
system is capable of steadily working in very low
speed, has much smaller torque ripple and exhibits good
dynamic and steady-state performance.
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[2]
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[3]
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