Direct Torque Control of
Induction Motors with Fuzzy Minimization Torque Ripple
ABSTRACT
Direct torque control (DTC) is a new method of induction
motor control. The key issue of the DTC is the strategy of selecting proper
stator voltage vectors to force stator flux and developed torque within a
prescribed band. Due to the nature of hysteresis control adopted in DTC, there
is no difference in control action between a larger torque error and a small
one. It is better to divide the torque error into different intervals and give
different control voltages for each of them. To deal with this issue a fuzzy
controller has been introduced. But, because the number of rules is too high
some problems arise and the speed of fuzzy reasoning will be affected. In this
paper, a comparison between a new fuzzy direct-torque control (DTFC) with space
vector modulation (SVM) is made. The principle and a tuning procedure of the
fuzzy direct torque control scheme are discussed. The simulation results, which
illustrate the performance of the proposed control scheme in comparison with
the fuzzy hysteresis connected of DTC scheme are given.
KEYWORDS
1.
Induction
machine
2.
Direct torque
control
3. Fuzzy logic
4. Space vector modulation
SOFTWARE:
MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig. 1. A novel direct torque
control scheme for ac motor drives (DTC) with fuzzy hysteresis and space vector
modulation
CONCLUSION:
In
this paper, a fuzzy direct torque control with space vector modulation is
analyzed in comparison to fuzzy hysteresis connected of DTC. The results
obtained by numerical simulation are given. In short, the advantages of
proposed fuzzy direct torque control using space vector modulation technique in
comparison with a fuzzy hysteresis of DTC are the following:
–
Reduced torque and flux distortion;
–
Constant switching frequency thanks to apply SVM;
–
Fast torque response because of the use of fuzzy controller;
–
Lower sampling time;
–
No problems during Low-speed operation;
–
No current and torque distortion caused by sector changes.
REFERENCES:
[1]
Casadei, D., serra, G., Tani, A, «Performance analysis of a DTC control scheme
for induction motor in the low speed range», in proceeding of EPE, (1997),
p.3.700-3.704, Trondheim.
[2]
Depenbrok. M, «Direct self-control (DSC) of inverter fed induction machine»,
In: IEEE Trans. On PE (1988), Vol. PE-3, No4, October 1988, p 420-429.
[3]
A. Cataliotti, G. Poma: “A Fuzzy approach for easy and robust control of an
induction motor”. EPE 97, pp 2.421-2.425, 1997.
[4]
J. R G Schonfield,”Direct torque control-DTC", ABB Industrial Systems Ltd.
[5]
Ned Gulley, J.-S. Roger Jang: Fuzzy Logic Toolbox for Use With Matlab".
The Math Works inc, Natick, Mass, 1996.
