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.

1. ELECTRICAL PROJECTS USING MATLAB/SIMULINK
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A 24-Pulse AC–DC Converter Employing a
Pulse Doubling Technique for Vector-
Controlled Induction Motor Drives
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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

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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).

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EXPECTED SIMULATION RESULTS:
Fig.3 Fig.4
Figure 3: AC mains current waveform of VCIMD fed by 6-pulse diode rectifier along with its
harmonic spectrum at full load (Topology ‘;A’).
Figure 4: AC mains current waveform of VCIMD fed by 6-pulse diode rectifier along with its
harmonic spectrum at light load (20%). (Topology ‘;A’).
Fig.5 Fig.6
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Figure 5: AC mains current waveform along with its harmonic spectrum at full load for
Topology ‘B’.
Figure 6: AC mains current waveform along with its harmonic spectrum at light load (20%) for
Topology ‘B’.
Fig.7 Fig.8
Figure 7: Dynamic response of proposed harmonic mitigator (Topology ‘C’) fed VCIMD with
load perturbation.
Figure 8: AC mains current waveform along with its harmonic spectrum at full load for
Topology ‘C’.
Figure 9: AC mains current waveform along with its harmoni spectrum at light load (20%) for
Topology ‘C’.
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0-9347143789/9949240245

5. ELECTRICAL PROJECTS USING MATLAB/SIMULINK
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0-9347143789/9949240245
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CONCLUSION:
Reduced rating autotransformer-based 12- and 24-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 to meet harmonic compliance’, Proc.IEEE,
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.