A 24-Pulse AC–DC Converter Employing a Pulse Doubling Technique for Vector-Controlled Induction Motor Drives
ABSTRACT:
This paper dealswith various multipulse AC–DC converters for improving the power quality in vector-controlled induc-tion motor drives (VCIMDs) at the point of common coupling. These multipulse AC–DC converters are realized using a reduced
rating autotransformer. Moreover,
DC ripple
reinjection is
used
to
double the rectification pulses resulting
in an effective harmonic mitigation. The proposed AC–DC converter is able to eliminate up to 21st harmonics in the
supply current. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed AC–DC converter. A
set
of power quality
indices
on input AC mains and on
the
DC bus for a VCIMD fed from different AC–DC converters is also given
to
compare
their
performance.
KEYWORDS:
1. Autotransformer
2. Multipulse AC–DC
converter
3. DC ripple reinjection
4. Pulse doubling
5. VCIMD.
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Figure 1: MATLAB block diagram of
proposed ac-dc converter fed VCIMD (Topology ‘D’).
Figure 2: The proposed 24-pulse ac-dc converter fed VCIMD (Topology C).
CONCLUSION:
Reducedratingautotransformer-based12-and24-pulse AC–DC converters have been designed, modelled and compared with a six-pulse AC–DC converter feeding VCIMD. DC ripple reinjection technique for pulse dou-bling has been used for harmonic reduction in VCIMD. The pulse doubling technique needs only two additional diodes along with a suitably tapped inductor. The pro-posed AC–DC converter has resulted in a reduction in
the rating of the magnetics, leading
to the saving
in the overall cost of the drive. The proposed AC–DC converter is able to achieve close to unity PF along with
a good DC link
voltage regulation in
the
wide operating range of the drive. The proposed AC–DC converter has
demonstrated its capability in improving various power quality indices at the AC mains in terms of THD of the supply current, THD of the supply voltage, PF and CF. It
can easily replace the existing
six-pulse converters without much alteration in the existing system layout
and equipments.
REFERENCES:
1. B.K. Bose,
‘Recent advances in power electronics’,IEEETrans.onPower Electronics, Vol. 7, No.
1, Jan. 1992, pp. 2-16.
2.
P. Vas, Sensorless vector and direct torque control, Oxford University Press,
1998.
3. IEEE
Guide for
harmonic control
and reactive compensation
of Static Power Converters, IEEE
Std. 519-1992.
4. Hahn Jaehong, Kang Moonshik, P.N. Enjeti & I.J. Pitel, ‘Analysis and design of harmonic subtracters for three phase rectifier equipment
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APEC’00, Feb. 2000, Vol. 1, pp. 211-217.
5. D.A.Paice, Power Electronic Converter Harmonics: Multipulse Methods for Clean Power, New York, IEEE Press 1996.
