High
Performance of Space Vector Modulation Direct Torque Control SVM-DTC Based on
Amplitude Voltage and Stator Flux Angle
ABSTRACT:
Various aspects related to controlling
induction motor are investigated. Direct torque control is an original high
performance control strategy in the field of AC drive. In this proposed method,
the control system is based on Space Vector Modulation (SVM), amplitude of
voltage in direct- quadrature reference frame (d-q reference) and angle of
stator flux. Amplitude of stator voltage is controlled by PI torque and PI flux
controller. The stator flux angle is adjusted by rotor angular frequency and
slip angular frequency. Then, the reference torque and the estimated torque is
applied to the input of PI torque controller and the control quadrature axis
voltage is determined. The control d-axis voltage is determined from the flux
calculator. These q and d axis voltage are converted into amplitude voltage. By
applying polar to Cartesian on amplitude voltage and stator flux angle, direct
voltage and quadratures voltage are generated. The reference stator voltages in
d-q are calculated based on forcing the stator voltage error to zero at next
sampling period. By applying inverse park transformation on d-q voltages, the
stator voltages in α and β frame are generated and apply to SVM. From the
output of SVM, the motor control signal is generated and the speed of the induction
motor regulated toward the rated speed. The simulation Results have
demonstrated exceptional performance in steady and transient states and shows
that decrease of torque and flux ripples is achieved in a complete speed range.
KEYWORDS:
1. Amplitude voltage
2.
Direct Torque Control (DTC)
3.
Space Vector Modulation (SVM)
4.
Stator flux angle
SOFTWARE: MATLAB/SIMULINK
BLOCK
DIAGRAM:
Fig. 1: DTC-SVM scheme
Fig.
2: Simulation of proposed SVM-DTC
CONCLUSION:
This
proposed method describes the performance of Direct Torque Control (DTC) based
on space vector modulation, amplitude voltage and stator flux angle. In this
system, hysteresis controller is substituted with PI torque controller and PI
flux controller while switching table is replaced by SVM in order to improve
the performance of this system especially at low speed, SVM is based on
amplitude voltage and stator flux angle. The stator flux angle is controlled by
PI torque controller and stator angular frequency and this gives a high
accuracy for the value of the angle due to presence of PI torque controller.
The amplitude voltage is controlled by PI torque and PI flux controller. This
proposed method shows a reduction ability of flux and torque ripple with
constant switching frequency and fast response of speed .This control technique
can be done practically by using Digital Signal Processing (DSP) board.
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