Harmonic mitigation using 12pulse ACDC converter in vectorcontrolled induction motor drives
ABSTRACT In this paper, a novel autotransformer with a reduced kilovoltampere rating is presented for harmonic current reduction in twelvepulse acdc converterfed vectorcontrolled induction motor drives (VCIMDs). Different transformer arrangements for 12pulsebased rectification are also studied and a novel harmonic mitigator capable of suppressing fifth, seventh, and 11th (most dominant harmonics) in the supply current is presented. The design procedure for the proposed autotransformer is presented to show the flexibility in the design for making it a costeffective replacement suitable for retrofit applications, where presently a sixpulse diode bridge rectifier is being used. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed harmonic mitigator. A set of powerquality indices on input ac mains and on a dc bus for a VCIMD fed from different 12pulse acdc converters is given to compare their performance.

Conference Paper: A new design methodology for multipulse rectifiers with Delta autoconnected transformers and a retrofit application in Adjustable Speed Drives (ASDs)
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ABSTRACT: Multipulse rectifiers can replace a conventional six pulse threephase rectifier (diode bridge) providing a DC voltage with low ripple, low Total Harmonic Distortion of current (THDi) and a high Power Factor (PF). In this context is presented a multipulse rectifier with generalized Deltadifferential autotransformer topology, which can provide any level of DC output voltage for any level of threephase AC input voltage. This paper presents all the possible configurations for Delta topology in order to choose, through graphics, one configuration that presents reduced weight and volume. The average voltage on the DC bus must be compatible with the DC voltage in the six pulse rectifier used in commercial ASDs. Therefore, it is possible to apply the retrofit technique to replace the conventional bridge rectifier by the proposed multipulse rectifier. Based on mathematic models and simulation results, an 18pulse rectifier with Delta topology, 220 V of line voltage, 315 V of DC output, and rating 2.5 kW of power was designed, implemented and applied for three different commercial ASDs. Experimental results as voltage and current waveforms and results about PF and THDi will be presented.Industry Applications (INDUSCON), 2012 10th IEEE/IAS International Conference on; 01/2012 
Conference Paper: A 12pulse converter featuring a rotating magnetic field transformer
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ABSTRACT: A 12Pulse Converter generally uses a phaseshifting transformer to get two sets of threephase voltages, but the magnitude of the line current harmonic is too high. In this paper, a new type of 12Pulse Converter featuring a rotating magnetic field transformer is presented. The design is based on the rationale of the induction machine, which can effectively reduce the line current harmonic and improve the power quality of the converter's DC output voltage.Modelling, Identification & Control (ICMIC), 2012 Proceedings of International Conference on; 01/2012  SourceAvailable from: npsc2010.uceou.edu[Show abstract] [Hide abstract]
ABSTRACT: A 24pulse rectifier has been designed for high voltage, low current applications. Four 3phase systems are obtained from a single 3phase source using novel interconnection of conventional singleand 3phase transformers. From two 30º displaced 3phase systems feeding two 6pulse rectifiers that are series connected, a 12pulse rectifier topology is obtained. Thus, from the four 3phase systems that are displaced by 15º two 12pulse rectifiers are obtained that are cascaded to realize a 24pulse rectifier. Phase shifts of 15º and 30º are made using phasor addition of relevant line voltages with a combination of singlephase and threephase transformers respectively. PSCAD based simulation and experimental results that confirm the design efficacy are presented.
Page 1
IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 21, NO. 3, JULY 2006
1483
Harmonic Mitigation Using 12Pulse
AC–DC Converter in VectorControlled
Induction Motor Drives
Bhim Singh, Senior Member, IEEE, G. Bhuvaneswari, Senior Member, IEEE, and Vipin Garg, Member, IEEE
Abstract—In this paper, a novel autotransformer with a reduced
kilovoltampere rating is presented for harmonic current reduc
tion in twelvepulse acdc converterfed vectorcontrolled induc
tion motor drives (VCIMDs). Different transformer arrangements
for 12pulsebased rectification are also studied and a novel har
monic mitigator capable of suppressing fifth, seventh, and 11th
(mostdominantharmonics)inthesupplycurrentispresented.The
design procedure for the proposed autotransformer is presented
to show the flexibility in the design for making it a costeffective
replacement suitable for retrofit applications, where presently a
sixpulsediodebridgerectifierisbeingused.Theeffectofloadvari
ation on VCIMD is also studied to demonstrate the effectiveness of
the proposed harmonic mitigator. A set of powerquality indices
on input ac mains and on a dc bus for a VCIMD fed from different
12pulse acdc converters is given to compare their performance.
Index Terms—Autotransformer, multipulse AC–DC converter,
powerquality improvement, vectorcontrolled induction motor
drive (VCIMD).
I. INTRODUCTION
W
quencyinductionmotor drives.These variablefrequencyinduc
tion motor drives are generally operated in vector control [1],
as it is an elegant way of achieving highperformance control
of induction motors in a way similar to the dc motor. These
vectorcontrolled induction motor drives (VCIMDs) are fed by
an uncontrolled ac–dc converter which results in injection of
current harmonics into the supply system. These current har
monics, while propogating through the finite source impedance,
result in voltage distortion at the point of common coupling,
thereby affecting the nearby consumers.
Various methods based on the principle of increasing the
number of pulses in ac–dc converters have been reported in
the literature to mitigate current harmonics [2]–[4]. These
methods use two or more converters, where the harmonics
generated by one converter are cancelled by another converter,
by proper phase shift. The autotransformerbased configu
rations [2] provide the reduction in magnetics rating, as the
transformer magnetic coupling transfers only a small portion
of the total kilovoltampere of the induction motor drive. These
autotransformerbased schemes considerably reduce the size
ITHtheproliferationofpowerelectronicconverters,the
majority of dc drives are being replaced by variable fre
Manuscript received February 9, 2005. Paper no. TPWRD000772005.
The authors are with the Department of Electrical Engineering, Indian Insti
tuteofTechnology,NewDelhi110016,India(email:bhim_singh@yahoo.com;
bhuvan225@gmail.com; vipin123123@gmail.com).
Digital Object Identifier 10.1109/TPWRD.2005.860265
and weight of the transformer. Autotransformerbased 12pulse
ac–dc converters have been reported [4] for reducing the total
harmonic distortion (THD) of the ac mains current. To ensure
equal power sharing between the diode bridges and to achieve
good harmonic cancellation, this topology needs interphase
transformers and impedancematching inductors, resulting in
increased complexity and cost. Moreover, the dclink voltage
is higher, making the scheme nonapplicable for retrofit appli
cations. To overcome the problem of higher dclink voltage,
Hammond [5] has proposed a new topology, but the transformer
design is very complex. To simplify the transformer design,
Paice [6] has reported a new topology for 12pulse acdc
converters. But this topology requires higher rating magnetics,
resulting in the enhancement of capital cost. Steffan et al. [7]
have reported a quasi 12pulse rectifier for harmonic reduction,
but here also the THD of the ac mains current at full load is
10.5% and at 40% load, it is around 20%. Kamath et al. [8]
have also reported a 12pulse converter, but the THD of the
ac mains current is high even at full load (10.1%) and as load
decreases, the THD increases further (17% THD at 50% load).
In this paper, a novel autotransformerbased 12pulse ac–dc
converter with reduced kilovoltampere (kVA) rating is pro
posed to feed the VCIMD. The presented technique for the
design of the autotransformer provides flexibility in design to
vary the output voltages to make it suitable for retrofit applica
tions (where presently, a sixpulse converter is being used, as
shown in Fig. 1) without much alterations in the system layout.
This topology results in improvement in THD of ac mains
current and power factor even under light load conditions.
II. TWELVEPULSE AC–DC CONVERTERBASED
HARMONIC MITIGATORS
For harmonic elimination, the required minimum phase shift
is given by [2]
Phase shift
Number of converters
For achieving 12pulse rectification, the phase shift between
the two sets of voltages may be either 0 and 30 or
this paper, various topologies based on
been studied to reduce the size of the magnetics.
Fig. 2 shows the schematic diagram of a 12pulse autotrans
formerbased ac–dc converter with a phase shift of
, referred as Topology “A” [3]. Similarly, Fig. 3 shows
the schematic diagram of a 12pulse autotransformerbased
ac–dc converter with a phase shift of
. In
haveand
and
andreferred
08858977/$20.00 © 2006 IEEE
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1484IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 21, NO. 3, JULY 2006
Fig. 1.
drive.
Sixpulse diode bridge rectifierfed vectorcontrolled induction motor
Fig.2.
and ??? ) fed VCIMD. (Topology A).
Autotransformerbased12pulseconverter(withaphaseshiftof???
as Topology “B” as per [4] and Fig. 4 shows the schematic
diagram of a 12pulse autotransformerbased ac–dc converter
with a phase shift of
and
as per [6]. In all of these topologies, the voltages produced by
the autotransformer
,, and
to supply voltages
,, and
voltages
, , andare at
voltages, resulting in 12pulse rectification.
referred as Topology “C”
are at
, where as the other set of
with respect to supply
with respect
III. DESIGN OF PROPOSED 12PULSE AC–DC CONVERTER
This section deals with the autotransformer arrangement for
the proposed 12pulse ac–dc converterbased harmonic miti
gator referred as Topology “D”. Various issues related to the
design of the suitable autotransformer for 12pulse configura
tion are presented here.
Fig. 3.
and ??? ) fed VCIMD. (Topology B).
Autotransformerbased 12pulse converter (with a phase shift of 15
Fig.4.
and ??? ) fed VCIMD. (Topology C).
Autotransformerbased12pulseconverter(withaphaseshiftof???
A. Design of Autotransformer for TwelvePulse Converter
Toachievethe12pulserectification,thefollowingconditions
have to be satisfied.
a) Two sets of balanced threephase line voltages are to be
produced, which are either
with respect to each other. Here,
to reduce the size of the magnetics.
b) The magnitude of these line voltages should be equal to
each other to result in symmetrical pulses and reduced
ripple in output dc voltage.
Fig. 5 shows the winding connection diagram of the pro
posed autotransformer for achieving the 12pulse rectification.
The phasor diagram shown in Fig. 6 represents the relationship
among various phase voltages.
From the supply voltages, two sets of threephase voltages
(phase shifted through
and
number of turns required for
calculated as follows. Consider phase “a” voltages as
or out of phase
phase shift is used
) are produced. The
phase shift areand
(1)
(2)
Assume the following set of voltages:
(3)
Similarly
(4)
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SINGH et al.: HARMONIC MITIGATION USING CONVERTER IN MOTOR DRIVES1485
Fig. 5. Proposed autotransformer winding connection diagram.
Fig. 6.
harmonic mitigator.
Vector diagram of phasor voltages for 12pulsebased proposed
(5)
where, V is the rootmeansquare (rms) value of the phase
voltage.
Using above equations,
and
equationsresultin
phaseshiftinanautotransformer.Thephaseshiftedvoltagesfor
phase “a” are
can be calculated. These
forthedesiredand
(6)
(7)
Thus, the autotransformer uses two auxiliary windings per
phase. A phaseshifted voltage (e.g.,
the following arrangements.
a) Tapping a portion (0.0227) of line voltage
b) Connecting one end of an approximate 0.138 times of line
voltage (e.g.,
) to this tap.
To ensure the independent operation of the rectifier groups,
interphase transformers (IPTs), which are relatively small in
size, are connected at the output of the rectifier bridges. With
thisarrangement,therectifierdiodesconductfor120 percycle.
With this transformer arrangement, the dclink voltage obtained
is slightly higher than that of a sixpulse diode bridge recti
fier output voltage due to 12pulse rectification. To make the
) is obtained by using
.
Fig. 7.
harmonic mitigator for retrofit applications.
Vector diagram of phasor voltages for 12pulsebased proposed
proposed harmonic mitigator suitable for retrofit applications,
the transformer design has been modified to make the dclink
voltage the same as that of the sixpulse diode bridge rectifier.
The phasor diagram shown in Fig. 7 represents the generalized
diagramshowingtherelationshipamongvariousphasevoltages
for achieving the variable magnitude transformer output volt
ages, which are phase shifted through
12pulse operation).
By following the above procedure, for the same dclink
voltage as that of a sixpulse diode bridge rectifier, the values
of
and are as
and are the new constants for achieving the same dclink
voltage as that of the sixpulse diode bridge rectifier. Now, the
phaseshifted voltages for phase ”a” are as
(for achieving the
and , where
(8)
(9)
Now, a phaseshifted voltage (e.g.,
the following arrangements.
a) Tapping a portion (0.0195) of line voltage
b) Connecting one end of an approximate 0.1402 times of
line voltage (e.g.,
) to this tap.
Thus, by simply changing the transformer winding tapping,
the same dclink voltage as that of the sixpulse diode bridge
rectifier is obtained. Fig. 8 shows the winding connection dia
gram of the proposed autotransformer for designing the auto
transformer suitable for retrofit applications. Fig. 9 shows the
proposed 12pulse rectificationbased harmonic mitigatorfed
VCIMD referred as topology “D.” The kVA rating of the trans
former is calculated as [2]
) is obtained by using
.
(10)
The kVA rating of the interphase transformer is also calcu
lated using the above relationship.
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1486 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 21, NO. 3, JULY 2006
Fig.8.
for retrofit applications.
Windingconnectiondiagramfortheproposedautotransformersuitable
Fig. 9.
fed VCIMD based on an autotransformer. (Topology D).
Proposed 12pulse converter (with a phase shift of ??? and ??? )
B. Design of Passive Tuned Filter
To improve the power quality, a passive shunt filter has been
designed in accordance with IEEE Standard 15312003 [9].
Fig. 10 shows the schematic diagram of the proposed harmonic
mitigator with a passive filter connected at the input. This
Topology is referred as “E.” Various issues involved with the
design of passive filters are given here.
1) Design Equations: The passive shunt filter is governed
by the following design equations [9], [10].
The impedance of the filter branch is given as
(11)
The resonance frequency can be written as
(12)
The inductor and capacitor impedances for th harmonic are
and
Quality factor: The quality of the filter is a measure of the
sharpness of tuning. A high value of quality factor results in a
very sharp tuned filter, whereas a low value results in highpass
wide bandwidth performance, resulting in higher losses.
. At resonance,.
Fig. 10.
shift of ??? and ??? ) fed VCIMD. (Topology E).
Autotransformerbased proposed 12pulse converter (with a phase
It is defined as
(13)
The kVA of the filter capacitor at power frequency (60 Hz) is
given as
(14)
where
the point of connection of the filter, C is the capacitance of the
filter capacitor,
is the reactance of inductor, and
reactance of the capacitor at the resonant frequency.
is the nominal linetoline voltage of the system at
is the
IV. VECTORCONTROLLED INDUCTION MOTOR DRIVE
Fig. 1 shows the schematic diagram of an indirect vector
controlledinductionmotordrive(VCIMD).Thistechniqueuses
two currents of motor phases, namely
speedsignal
.TheclosedloopPIspeedcontrollercompares
the reference speed
with motor speed
reference torque
(after limiting it to a suitable value)
andand the motor
and generates
(15)
where
limiting it to a suitable value) and
speed error at the th and
proportional and integral gain constants.
The flux control signal
vector controller which calculates the torque component of and
the flux angle
as follows:
andare the output of the PI controller (after
and
instants.
refer to
are theand
along with are fed to the
(16)
(17)
(18)
(19)
(20)
where
rotor;
number of poles, mutual inductance, and rotor leakage factor,
respectively;
andare the value of rotor flux angles
is the magnetizing current;
is the angular velocity of rotor; P, M, and
is the slip speed of
are the
Page 5
SINGH et al.: HARMONIC MITIGATION USING CONVERTER IN MOTOR DRIVES 1487
Fig. 11. MATLAB block diagram of VCIMD.
Fig. 12.
VCIMD (topology “D”).
MATLAB block diagram of the proposed harmonic mitigatorfed
Fig. 13.
VCIMD (Topology “E”).
MATLAB block diagram of the proposed harmonic mitigatorfed
at thand( 1)thinstants,respectively,and
time taken as 100
s.
These currents (
,
converted to stationary frame threephase currents (
as given below
isthesampling
), in synchronously rotating frame, are
,,)
(21)
(22)
(23)
where
These threephase reference currents generated by the vector
controller are compared with the sensed motor currents (
and). The calculated current errors are
,, and are the threephase reference currents.
,,
where(24)
ThesecurrenterrorsareamplifiedandfedtothePWMcurrent
controller which controls the duty ratio of different switches
in VSI. The VSI generates the PWM voltages being fed to the
Fig.14.
perturbation.
DynamicresponseofasixpulsedioderectifierfedVCIMDwithload
Fig. 15.
load in a sixpulse diode bridge rectifierfed VCIMD.
AC mains current waveform along with its harmonic spectrum at full
motor to develop the necessary torque for running the motor at
a given speed under given loading conditions.
V. MATLABBASED SIMULATION
The proposed harmonic mitigators, along with the VCIMD,
are simulated in a MATLAB environment along with
SIMULINK and powersystemblockset (PSB) toolboxes.
Fig. 11 shows the MATLAB model of a vectorcontrolled
induction motor drive. The VCIMD consists of an induction
motor drive controlled using an indirect vectorcontrol tech
nique. Fig. 12 shows the MATLAB model of the proposed
harmonic mitigator based on 12pulse rectification to simulate
its performance. Fig. 13 shows the MATLAB model of the pro
posed harmonic mitigator along with a passive filter connected
on the supply side to further improve various powerquality
indices. The simulated results have been analyzed to study the
effect of load variation on the drive on various powerquality
indices as well as to show the reduction in rating of magnetics
in the proposed configuration.
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1488 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 21, NO. 3, JULY 2006
Fig.16.
load (20%) in a sixpulse diode bridge rectifierfed VCIMD.
ACmains currentwaveformalongwithitsharmonicspectrumatlight
Fig. 17.
load for Topology “A.”
AC mains current waveform along with its harmonic spectrum at full
VI. RESULTS AND DISCUSSION
The proposed harmonic mitigator along with the VCIMD
have been simulated to demonstrate the performance of the
proposed system. Fig. 14 shows the dynamic performance
along with load perturbation on the VCIMD fed by a sixpulse
diode bridge rectifier. It consists of supply voltage
current
, rotor speed “” (in electrical rad/sec), threephase
motor currents
, motordeveloped torque “
and dclink voltage
(V). Fig. 15 shows the supply current
waveform along with its harmonic spectrum at full load. The
THD of the ac mains current at full load is 31.2%, which dete
riorates to 57.7% at light load as shown in Fig. 16. Moreover,
the power factor at full load is 0.937, which deteriorates to
0.848 as the load is reduced. These results show that there is
a need for improving the power quality at the ac mains using
some harmonic mitigators which can easily replace the existing
sixpulse converter.
, supply
” (in Nm)
Fig.18.
load (20%) for Topology “A.”
ACmainscurrentwaveformalongwithitsharmonicspectrumatlight
Fig. 19.
load for Topology “B.”
AC mains current waveform along with its harmonic spectrum at full
Fig.20.
load (20%) for Topology “B.”
ACmainscurrentwaveformalongwithitsharmonicspectrumatlight
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SINGH et al.: HARMONIC MITIGATION USING CONVERTER IN MOTOR DRIVES 1489
Fig. 21.
load for Topology “C.”
AC mains current waveform along with its harmonic spectrum at full
Fig. 22.
load (20%) for Topology “C.”
ACmainscurrentwaveformalongwithitsharmonicspectrumatlight
A. Performance of TwelvePulse RectificationBased
Harmonic Mitigators
Different configurations of 12pulse ac–dc converters have
been modeled and simulated to compare their relative perfor
mance in terms of different powerquality indices.
1) Autotransformer With
simulation results of an autotransformer (with phase shift of
and)based ac–dc converter (Topology “A”)fed
VCIMD are shown in Figs. 17 and 18. Fig. 17 shows the wave
form of the supply current along with its harmonic spectrum
at full load and Fig. 18 shows these parameters at light load
(20%) in topology “A.” The THD of supply current at full load
is 7.02% and that at light load is 10.23%, whereas the power
factor under these conditions is 0.973 and 0.975, respectively.
Here, the dclink voltage is higher than that of a 6pulse diode
bridge rectifier. In topology “B”, the THD of the ac mains cur
rent at full load is 6.24%and at light load, it is 14.25% as shown
in Figs. 19 and 20, respectively. Here again, the dclink voltage
is high. In topology “C”, the THD of the ac mains current at
full load is 6.59% and 13.13% at light load (20%) as shown in
andPhase Shift: The
Fig. 23.
load for Topology “D.”
AC mains current waveform along with its harmonic spectrum at full
Fig.24.
load (20%) for Topology “D.”
ACmainscurrentwaveformalongwithitsharmonicspectrumatlight
Figs. 21 and 22, respectively. This topology needs magnetics as
high as 43.56% of the drive rating. There is a need for a suitable
ac–dc converter which has the same dclink voltage as that of
a sixpulse diode bridge rectifier (for retrofit applications) and
which needs small magnetics.
2) Proposed Harmonic Mitigator: The supply current
waveform at full load along with its harmonic spectrum is
shown in Fig. 23 (Topology “D”), which shows that the THD
of the ac mains current is 8.17% and the power factor obtained
is 0.975. Fig. 24 shows the supply current waveform along with
its harmonic spectrum under light load condition (20%). At
light load condition, the THD of the ac mains current is 9.40%
and the power factor is 0.969. To improve the powerquality
indices further, a passive shunt filter has been connected at
the supply input (Topology “E”). Fig. 25 shows the dynamic
performance of the proposed harmonic mitigator (Topology
“E”) at starting and load perturbation. Fig. 26 shows the supply
current waveform along with its harmonic spectrum at full load
condition, showing a THD of 6.68% and a power factor of
0.982. The supply current waveform under light load condition
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1490 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 21, NO. 3, JULY 2006
Fig. 25.
converterfed VCIMD with load perturbation for Topology “E.”
Dynamic response ofproposed 12pulse autotransformerbased acdc
Fig. 26.
load for Topology “E.”
AC mains current waveform along with its harmonic spectrum at full
(20%), along with its harmonic spectrum, is shown in Fig. 27,
which shows that the THD of the ac mains current is 7.52% and
the power factor is 0.98.
Table I shows the effect of load variation on the VCIMD to
study various powerquality indices. It shows that the proposed
harmonic mitigator is able to perform satisfactorily under load
variation on VCIMD with almost unity power factor (always
higher than 0.98) and a THD of supply current always less than
8%. This is within the IEEE Standard 519 [11] limits for SCR
20.TableIIshowsthevariationofsupplycurrent
verter input current
with a load on VCIMD. It can be ob
served that the supply current
verter input current
.
The variation of THD of the ac mains current and power
factor in VCIMD fed from a sixpulse and the proposed
12pulse ac–dc converters is shown in Figs. 28 and 29,
respectively, showing a remarkable improvement in these
powerquality indices. Table III shows a comparative study
andcon
is always less than the con
Fig.27.
load (20%) for Topology “E.”
ACmainscurrentwaveformalongwithitsharmonicspectrumatlight
TABLE I
POWERQUALITY INDICES UNDER VARYING LOADS IN PROPOSED
HARMONIC MITIGATORFED VCIMD
TABLE II
COMPARISON OF SUPPLY CURRENT AND CONVERTER INPUT
CURRENT IN DIFFERENT CONVERTERS
of different powerquality indices of a VCIMD fed from a
sixpulse converter and different 12pulse converters.
The converters in topologies A and B result in a higher
dclink voltage than a sixpulse diode bridge rectifier. So these
topologies cannot be used in retrofit applications. The auto
transformer in Topology “C” results in a dclink voltage that is
almost the same as that of a sixpulse diode bridge rectifier, but
the rating of the magnetics is high 20.825 kVA (43.56% of the
drive rating), which is on a higher side as shown in Table IV.
The proposed autotransformerbased 12pulse ac–dc converter
gives the same dclink voltage as that of a sixpulse diode
bridge rectifier, making it suitable for retrofit applications.
Moreover, the rating of the autotransformer is 9.3 kVA. It needs
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SINGH et al.: HARMONIC MITIGATION USING CONVERTER IN MOTOR DRIVES 1491
TABLE III
COMPARISON OF POWERQUALITY PARAMETERS OF A VCIMD FED FROM DIFFERENT 12PULSE CONVERTERS
Fig. 28.
sixpulse and proposed 12pulse acdc converter (Topology “E”) fed VCIMD.
Variation of THD of the ac mains current with load on VCIMD in
Fig. 29.
proposed 12pulse ac–dc converter (Topology “E”’) fed VCIMD.
Variation of power factor with load on VCIMD in sixpulse and
TABLE IV
RATING OF MAGNETICS IN DIFFERENT CONVERTER TOPOLOGIES
a small rating interphase transformer of 1.38 kVA, resulting in
total magnetics of 10.68 kVA (22.34% of drive rating).
VII. CONCLUSION
A novel autotransformerbased 12pulse ac–dc converter has
been modeled with a VCIMD load. The design technique of the
proposed converter has shown the flexibility to design the trans
former suitable for retrofit applications with variable frequency
induction motor drivesoperating undervaryingload conditions.
The proposed harmonic mitigator has resulted in the reduction
in rating of the magnetics, leading to the saving in overall cost
of the drive. The effect of load variation on the VCIMD on var
ious powerquality indices has also shown the efficacy of the
proposed harmonic mitigator in improving these indices. The
observed performance of the proposed harmonic mitigator has
been found better than the existing 12pulse converter config
urations. The performance of the proposed harmonic mitigator
has demonstrated thecapabilityof this converterresulting inthe
improvement of powerquality indices at the ac mains in terms
oftheTHDofthesupplycurrent,THDofsupplyvoltage,power
factor, and crest factor. On the dclink side too, it provides a re
markable improvement in ripple factor of the dclink voltage.
It can easily replace the existing sixpulse converters without
much alteration in the existing system layout and equipment.
APPENDIX
MOTOR AND CONTROLLER SPECIFICATIONS
Threephase squirrel cage induction motor
(37.3 kW), threephase, fourPole, Yconnected, 460 V, 60
Hz,
,
,
Controller parameters
PI controller:
DClink parameters:
Magnetics ratings
Twelvepulsebased converter:
9.3 kVA, interphase transformer 1.38 kVA, passive filter
2.22 kVA.
50 HP
,,
,.
,;
mH, F.
Autotransformerrating
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1492 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 21, NO. 3, JULY 2006
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[11] IEEEGuide for HarmonicControl and Reactive Compensation of Static
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Bhim Singh (SM’99) was born in Rahamapur, India,
in 1956. He received the B.E. (electrical) degree
from the University of Roorkee, Roorkee, India, in
1977 and the M. Tech. and Ph.D. degrees from the
Indian Institute of Technology (IIT), Delhi, New
Delhi, India, in 1979 and 1983, respectively.
In 1983, he joined the Department of Electrical
Engineering, University of Roorkee, as a Lecturer,
and in 1988 became a Reader. In December 1990,
he joined the Department of Electrical Engineering,
IIT Delhi, as an Assistant Professor. He became an
Associate Professor in 1994 and a full Professor in 1997. His field of interest
includes power electronics, electrical machines and drives, active filters, static
VAR compensator, and analysis and digital control of electrical machines.
Dr. Singh is a Fellow of Indian National Academy of Engineering (INAE),
theInstitutionofEngineers(India)[IE(I)],andtheInstitutionofElectronicsand
Telecommunication Engineers (IETE), a Life Member of the Indian Society for
TechnicalEducation(ISTE),theSystemSocietyofIndia(SSI),andtheNational
Institution of Quality and Reliability (NIQR).
G. Bhuvaneswari (SM’99) received the M.Tech.
and Ph.D. degrees from the Indian Institute of
Technology (IIT), Madras, India, in 1988 and 1992,
respectively.
Currently, she is an Assistant Professor, Depart
ment of Electrical Engineering, IIT Delhi, New
Delhi, India, where she has been since 1997. Her re
search interests include power electronics, electrical
machines, and power conditioning. She is a fellow
of IETE.
Vipin Garg (M’05) was born in Kurushhetra,
Haryana, India, in 1972. He received the B.Tech.
(Electrical) and M.Tech. degrees from Regional
Engineering College, Kurukshetra, in 1994 and
1996, respectively, and is currently pursuing the
Ph.D. degree at the Indian Institute of Technology
Delhi, New Delhi.
HejoinedtheIndianRailwaysServiceofElectrical
Engineers (IRSEE),New Delhi, asan Assistant Elec
trical Engineer and became Divisional Electrical En
gineer in 2002. His research interests include power
electronics and electric traction and drives.
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