Power Quality Improvements Using Multipulse Converters

11

Seminar Seminar onon

Power Quality Improvements Power Quality Improvements Using Multipulse ConvertersUsing Multipulse Converters

ByBy

Prof. Bhim Singh, Prof. Bhim Singh, Senior Member, IEEESenior Member, IEEE Department of Electrical EngineeringDepartment of Electrical Engineering

Indian Institute of Technology DelhiIndian Institute of Technology Delhi New Delhi-110016, India New Delhi-110016, India

22

Multipulse converters are converters providing Multipulse converters are converters providing more than six pulses of DC voltagemore than six pulses of DC voltage per cycle from per cycle from AC input.AC input.

Or the converter having Or the converter having more steps in AC input more steps in AC input currentcurrent than that of six pulse bridge rectifier supply than that of six pulse bridge rectifier supply current.current.

Bridge rectifier is the basic block required for AC-Bridge rectifier is the basic block required for AC-DC conversion, however, full-wave and half-wave DC conversion, however, full-wave and half-wave rectifiers are also used up to 120kW ratings.rectifiers are also used up to 120kW ratings.

Phase shifting transformers are used to derive Phase shifting transformers are used to derive multiple phase supply from three-phase AC mains multiple phase supply from three-phase AC mains using different combinations of transformer using different combinations of transformer windings such as star, delta, zigzag, fork, polygon, windings such as star, delta, zigzag, fork, polygon, etc.etc.

What are Multipulse AC-DC Converters?

33

Problems in AC-DC ConvertersProblems in AC-DC Converters

The major The major problemsproblems in AC-DC converters are in AC-DC converters are injection of harmonicsinjection of harmonics at input and output at input and output . .

Harmonics causeHarmonics cause dielectric, thermal or dielectric, thermal or voltage stress, which cause voltage stress, which cause premature ageingpremature ageing of electrical insulation.of electrical insulation.

Voltage distortionVoltage distortion at point of common at point of common coupling takes place due to the voltage drop coupling takes place due to the voltage drop of harmonic currents flowing through system of harmonic currents flowing through system impedances.impedances.

Capacitor bank Capacitor bank overloadingoverloading due to system due to system resonance.resonance.

44

Problems in AC-DC ConvertersProblems in AC-DC Converters

Interference Interference on telephone and on telephone and communication lines due to noise induced communication lines due to noise induced from the power conductors.from the power conductors.

Poor power factorPoor power factor.. Equipment damageEquipment damage from voltage spikes from voltage spikes

created by high frequency resonance created by high frequency resonance resulting from notching. resulting from notching.

55

Power Quality Standards in AC-DC Power Quality Standards in AC-DC

ConvertersConverters IEEE Standard IEEE-519.IEEE Standard IEEE-519.

established in 1981 as the “Recommended Practices and established in 1981 as the “Recommended Practices and requirements for Harmonics Control in Electrical Power System” requirements for Harmonics Control in Electrical Power System” giving limits on current and voltage distortion and revised in giving limits on current and voltage distortion and revised in 19921992

IEC 61000 IEC 61000 The electric equipments have been categorized in four groups: The electric equipments have been categorized in four groups: Class- A, B, C and D, for the purpose of harmonic current Class- A, B, C and D, for the purpose of harmonic current limitationlimitation..

IEEE-1531 IEEE-1531 IEEE-1531 (issued in 2003) gives necessary guidelines for IEEE-1531 (issued in 2003) gives necessary guidelines for specifications for the use of passive shunt harmonic filters in low specifications for the use of passive shunt harmonic filters in low and medium voltage electric power systemsand medium voltage electric power systems

66

Current Distortion Limits for General Distribution Systems(120 V Through 69 000 V), IEEE-519 Std.

Maximum Harmonic current Distortion in Percent of IL

Individual Harmonic order (Odd Harmonics)

ISC/ IL<11 11h17 17h23 23h35 35h TDD

<20* 4.0 2.0 1.5 0.6 0.3 5.0

20<50 7.0 3.5 2.5 1.0 0.5 8.0

50<100 10.0 4.5 4.0 1.5 0.7 12.0

100<1000 12.0 5.5 5.0 2.0 1.0 15.0

>1000 15.0 7.0 6.0 2.5 1.4 20.0

Even harmonics are limited to 25% of the odd harmonic limits above.

Current distortion that results in a dc offset, e.g., half-wave converters, are not allowed

*All power generation equipment is limited to these values of current distortion, Regardless of actual ISC/ IL

Where,Isc= maximum short-circuit current at PCC.

IL= maximum demand load current (fundamental frequency component) at PCC

77

Current Distortion Limits for General Subtransmission Systems (69001 V through 161 000 V), IEEE-519 Std.

88

Limits for Class A equipment, IEC-61000 Std.

Harmonic order n

Maximum permissible harmonic Current A

Odd harmonics 3 2.3 5 1.14 7 0.77 9 0.40 11 0.33 13 0.21

15<=n<=39 0.15 15/n Even Harmonics

2 1.08 4 0.43 6 0.3

8<= n <= 40 0.23 8/n

99

Advantages of Multi-pulse AC-DC Advantages of Multi-pulse AC-DC ConvertersConverters

The performance parameters such as total-The performance parameters such as total-harmonic-distortion (THD) of harmonic-distortion (THD) of AC mainsAC mains current and ripple factor of current and ripple factor of output DC output DC voltagevoltage improve, simultaneously. improve, simultaneously.

The improvement is The improvement is independentindependent of supply of supply frequency frequency variation, unlike passive filters.variation, unlike passive filters.

Minimal or no controlMinimal or no control required as Diodes required as Diodes and/or thyristors are mainly used.and/or thyristors are mainly used.

Economic, maintenance free Economic, maintenance free andand efficient efficient..

1010

Phase shifting transformers are used to derive multiple phase supply from three-phase AC mains using different combinations of transformer windings such as star, delta, zigzag, fork, polygon, etc.

1111

Application PotentialApplication Potential

Non-Isolated Uncontrolled Non-Isolated Uncontrolled RectifiersRectifiers : :

Front end of Switched mode Front end of Switched mode powers like-SMPS, UPS, powers like-SMPS, UPS, AC-DC motor drives, dc AC-DC motor drives, dc servo drives.servo drives.

aircraft VSCF (Voltage aircraft VSCF (Voltage source controlled source controlled frequency) systems and frequency) systems and aircraft maintenance aircraft maintenance systems using 60Hz/400Hz systems using 60Hz/400Hz converter systems. converter systems.

Isolated Uncontrolled Isolated Uncontrolled RectifiersRectifiers : :

Railways working on DC.Railways working on DC. The welding equipment The welding equipment

working on high frequencyworking on high frequency

1212

Application PotentialApplication Potential

Non-Isolated Controlled Non-Isolated Controlled Rectifiers:Rectifiers:

DC motor drive system DC motor drive system with regenerative with regenerative capacity.capacity.

Some power supplies of Some power supplies of large rating also use non-large rating also use non-isolated dual converters isolated dual converters

Isolated Controlled Isolated Controlled RectifiersRectifiers : :

HVDC systems.HVDC systems. Battery energy storage Battery energy storage

systems.systems. Adjustable speed Adjustable speed

synchronous motor drive synchronous motor drive of large power ratings for of large power ratings for applications such as applications such as mining.mining.

Arc furnaces Arc furnaces

1313

Y

Y

harmonic filters

Reactivepower

(closed loop)control

TFS

CAD

Flicker (openloop) control

T1

highvoltage

bus medium voltage bus

PLL

+

-

Reg

actuator

Iarc

V arc

V arc

-

+

V arc

L d

low voltage side

Reg FADIdc

current control of a thyristor bridge

TCR

T2A

T2B

+ +

(TFS = Thyristor firing scheme; CAD = Conduction Angle Determinator; FAD = Firing Angle Determinator; PLL = phase Locked Loop

Typical power supply system of DC arc furnaces

1414

vb

v c

va

N

+

-

Load

Interphase transformer

Rectifiertransformer 34.5

kV / 606 V,2.4MVA

34.5 kV Bus

700 V

A model of twelve pulse railway rectifier system

1515

DiodeRectifier

SmoothingCapacitor

InverterRectifier

&Filter

ArcLoad

ControlCircuits

Premier Stage Secondary Stage

400 V,3-phasesupply

Block schematic of welding inverter power supply system

1616

~ ~

~

~ ~

~

A

B

C

a

b

c

A'

B'

C'

NN

L c

L c

L c

Id

Rectifier (or source sideconverter)

Inverter (or machine sideconverter)

+

-

-

+

v d1v d2

L d

T F

ic

ia

Motor

Inverter

Phase delayand firing

circuit

DC supply

Motor

del * or del '*

f del * or del '

Rotor positionand f *

Rotorpositionsensor

Field

Load commutated current source inverter fed synchronous motor

Brushless DC motor

1717

Six-Pulse Converter with Capacitor Filter

THD =62.3%

1818

Six-Pulse Converter with Inductor-Capacitor Filter

THD =32.7%

1919

PASSIVE WAVESHAPING

LOW COST

RUGGED STRUCTURE

LESS LOSSES

HIGH EFFICIENCY

LESSER RATING TRANSFORMER REQD IN AUTOTRANSFORMER BASED TOPOLOGIES

2020

MULTIPULSE CONVERTERSMULTIPULSE CONVERTERS

CLASSIFICATION OF MULTIPULSE AC-DC CONVERTERS based on phase shift

Pulse Based Configurations

Twelve-Pulse Converters 00 and 300 Phase Shift

Twelve-Pulse Converters Based on +150 and -150 Phase Shift

Twenty-Four-Pulse Converters Based on 150 Phase Shift

Eighteen -Pulse Converters Based on +200 and -200 Phase Shift

Thirty-Pulse Converters Based on 120 Phase Shift

Phase Shift = 60Phase Shift = 6000 / Number of Six-Pulse Converters / Number of Six-Pulse Converters

2121

Full-Wave

AC-DC Converters with reduced harmonics

Controlled (Bi - directional)

multi-pulse converters

Uncontrolled (Uni-directional)

multi-pulse converters

Non-Isolated multi-pulse converters

Non-Isolated multi-pulse converters

Isolated multi-pulse converters

Isolated multi-pulse converters

Bridge-converter

Full-Wave

Bridge-converter

Full-Wave

Bridge-converter

Full-Wave

Bridge-converter

CLASSIFICATION OF MULTIPULSE AC-DC CONVERTERS

2222

Non-Isolated Multipulse AC-DC Non-Isolated Multipulse AC-DC ConvertersConverters

2323

Autotransformer Connection Based Configurations

Star Connected Autotransformer

Delta Connected Autotransformer

Polygon Connected Autotransformer

Delta-Polygon Connected Autotransformer

Hexagon Connected Autotransformer

T- Connected Autotransformer

Zigzag Autotransformer

2424

MULTIPHASE CONVERTERS

CLASSIFICATION OF MULTI-PHASE AC-DC CONVERTERS

Nine-Phase AC-DC Converters

Fifteen-Phase AC-DC Converters

Phase Number Based Configurations

2525

CONVENTIONAL WYE DELTA TRANSFORMER

LARGE KVA RATING OF TRANSFORMER

MORE COST

DIFFICULT TO MAKE IDENTICAL WYE AND DELTA WINDINGS

2626

2727

MODELING AND DESIGN OF MULTIPULSE

AC-DC CONVERTERS Twelve-Pulse Converters Based on +150 and -150 Phase Shift


Va = K1*Va - K2* Vb

Va = K1*Va- K2*Vc Vb’

Va

Va”Va’

Vb

Vb”Vc’

Vc

Vc” N

K1

K2

Va=V00, Vb=V-1200 , Vc = V 1200

Va = V +150 , Vb = V-

1050, Vc = V 1350

Va = 0.816 Va - 0.298 Vb

Va = 0.816 Va - 0.298 Vc

Vb’

VaVa’ Va”

Vb

Vb”Vc’

Vc

Vc”

150150

150

150150

150

K1

K2K2

2828

3 Phase, 415V,50 Hz

isa

IGBT Based Inverter

A

B

C

Cd

-

+a'

b'

c'

a''

b"

c"

Autotransformer

Zs

Zs

Zs

Vb’

Va

Va”Va’

VbVb”Vc’Vc

Vc” N3

phase,VCIMD

+

Vdc

+

6 Pulse Diode Bridge Rectifier

isb

isc

Ld

IPT

IPT


2929

AC MAINS CURRENT WAVEFORM AND ITS HARMONIC SPECTRUM

FULL LOAD LIGHT LOAD (20%)

Magnetics Rating = 36%THD = 9.89% THD = 15.22%

3030

K1 = 0.8 and K2 = 0.2928.

RETROFIT ARRANGEMENT

Va = 0.8 Va - 0.2928 Vc

Va = 0.8 Va - 0.2928 Vb

Va = K1*Va - K2* Vb

Va = K1*Va- K2*Vc

3131

Full LoadFull Load Light LoadLight Load

3232

Twelve-Pulse Converters Based on +00 and 300 Phase Shift


Vb’Va’

Vc’

Vc

Va

Vb

Design of Autotransformer

Va =Va + K1 Vca + K2Vbc

Va=V00, Vb=V-1200 , Vc = V1200

Va = V +300 , Vb

= V-900, Vc = V 1500

K1 =0.0843

K2 = 0.229

Va = Va + 0.0843 Vbc + 0.229 Vca

3333

3 phase,VC

IMD

IGBT Based Inverter

A

B

C

3 Phase, 415V, 50 Hz

+

Vdc

Cd

-

+

+

-

a

b

c

a'

b’

c'

Autotransformer

Zs

Zs

Zs

Vb’Va’

Vc’

Vc

Va

Vb

Ld

THD = 9.51% THD = 15.66%


3434

Shortfalls in 12-Pulse Converters

High THD of ac mains current

Not within IEEE Standard 519 limits

Use of 18-pulse converters

THD of ac mains current well within IEEE Standard limits

Near unity power factor operation

3535

CONFIGURATIONS

3636

Vb’

Va

Va”Va’

Vb

Vb”Vc’

Vc

Vc” N

K1

K2

Va = K1Va - K2 Vb

Va = K1Va- K2Vc

Va=V00, Vb=V-1200 , Vc = V 1200

Va = V +200 , Vb = V-

1000, Vc = V 1400

K1 =0.7421

K2 = 0.395

Va = 0.7421 Va - 0.395 Vb

Va = 0.7421 Va - 0.395 Vc

3737

IGBT Based Inverter

A

B

C



Cd

-


+

+

a'

b'

c'

a''

b"

c"

Autotransformer

Zs

Zs

Zs a

b

c

Vb’

Va

Va”Va’

VbVb”Vc’Vc

Vc” N3

phase,VCIMD

+

Vdc

+

IPT

IPT

isa

isb

isc

ica

icb

icc

Ld

3838Magnetics Rating = 41%

THD = 2.71%THD = 4.19%


3939

Vb’

Va’

Vc’

Vc

Va

Vb

Va”

Vb”

Vc”

0.04

0.040.177 0.177

200 200

K1K2

Vbc

Vab

Vca

Vb”

Va”Va’

Vc’

Vc” Vb’

Vc Vb

Va

Va = Va + K1Vca - K2 Vbc

Va =Va + K1Vab + K2 Vbc

Va=V00, Vb=V-1200 , Vc = V 1200

Va = V +200 , Vb = V-1000, Vc

= V 1400

K1 = 0.0402

K2 = 0.177

Va = Va + 0.0402 Vca - 0.177 Vbc

Va =Va + 0.0402Vab + 0.177 Vbc

4040

IGBT Based Inverter

A

B

C



Cd

-


+

+

a'

b'

c'

a''

b"

c"

Autotransformer

Zs

Zs

Zs

a

b

c

3phase,VC

IMD

+Vdc

+

IPT

IPT

isa

isb

isc

Ld

Vb’

Va’

Vc’

Va

Vb

Va”

Vb”

Vc”

Vc

4141Magnetics Rating = 22.55%

THD = 4.17% THD = 5.56%Full LoadFull Load Light LoadLight Load

4242

4343

CONFIGURATIONS

4444

Va1 = K1Va 00 - K2 Vb-1200

Va2 = K3Va - K4Vb-1200

Va3 = K1Va00 - K2Vc 1200

Va4 = K3Va 00 - K4Vc1200

Va1 = V 7.50 , Vb1 = V-112.50, Vc1 = V127.50

Va2 = V 22.50, Vb2 = V-97.50, Vc2 = V122.50

Va3 = V -7.50, Vb3 = V-127.50, Vc3 = V112.50 Va4 = V -22.50, Vb4 = V-142.50, Vc4 = V97.50

Va

Vb2

Va2 Va4

VbVc

7.507.50

22.50

22.50

Va1

Vb1

Vb3

Vb4

Vc1

Vc2

Vc3

Vc4

Va3

K1 =0.916, K2 = 0.15069, K3 = 0.7028 and K4 = 0.44189

Vb1

Va

Va1

VbVc

N

Va2

Va3

Va4

Vb2

Vb3Vb4Vc1 Vc2

Vc3

Vc4

K1

K3

K2

K4

4545

Va Va3

22.507.50

K2

K2'

K1

K1'

K3K3'

K4

K4'

Va2

Va2'

Va3'

VbVc

K4’= 0.4256

K1=0.88

24K2

= 0.1451

K3’ = 0.677

Va1’=0.916Va 00 – 0.15069Vb-1200

Va2’ =0.7028Va 00 – 0.44189Vb-1200

Va3’ =0.916Va00 – 0.15069Vc 1200

Va4’ =0.7028Va00 – 0.44189Vc 1200

4646

IGBT Based Inverter

A

B

C3 Phase, 415V,

50 Hz AC Mains

6 Pulse Diode Bridge Rectifiers

Cd

-

+

Zs

Zs

Zs

3 phase,VCIMD

+Vdc

IPT

isa

isb

isc

Ld

+

IPT

+

+

a1

b1

c1

a2

b2

c2

a3

b3

c3

a4

b4

c4

Vb1

VaVa1

VbVc

N

Va2

Va3

Va4

Vb2

Vb3Vb4Vc1 Vc2

Vc3

Vc4

Autotransformer

4747

THD = 3.45% THD = 6.56%


4848

CURRENT INJECTION IN TWELVE-PULSE AC-DC CONVERTERS

4949


isa

IGBT Based Inverter

A

B

C

Cd

+a'

b'

c'

a''

b"

c"Autotransformer

Zs

Zs

Zs

Vb’

Va

Va”Va’

VbVb”Vc’Vc

Vc” N 3phase,VC

IMD

+

Vdc

+

Inter PhaseTransformer


isb

isc

ZSBT

D1D2

ZSBT

Ld


Vd1 Vd2

5050

THD = 3.83% THD = 5.25%


5151

Nine-Phase AC-DC Converters


Phase shift = 3600/ Number of output phases

Va1

Va

VbVc

Va2

Vb1

Vb2Vc1

Vc2

K1

K2

Va1 = Va + K1Vca - K2 Vbc

Va2 =Va + K1Vab + K2Vbc

Va=V00, Vb=V-1200 , Vc = V1200

Va1 = V 400 , Vb1 = V-800, Vc1 = V1600

Va2 = V -400, Vb2 = V-1600, Vc2 = V800

K1 =0.156 K2 = 0.293

Va1 = Va + 0.156Vca - 0.293 Vbc

Va2 = Va + 0.156Vab + 0.293Vbc

Va

400 400

Vbc

Vab

Vca

Va1

Vc Vb

Va2

Vb1

Vb2Vc1

Vc2

400

400

400400400

400

400

5252

IGBT Based Inverter

A

B

C



Cd

-

+

+

a1

b1

c1

a2

b2

c2

Autotransformer

Zs

Zs

Zs

a

b

c

3 phase,VC

IMD

+

Vdc

+

IPT

IPT

isa

isb

isc

Ld

Va1

Va

Vb

Vc

Va2

Vb1

Vb2Vc1

Vc2

5353

THD = 3.79% THD = 7.39%


5454

Fifteen-Phase AC-DC Converters


Vb1

Va

Va1

VbVc

N

Va2

Va3Va4

Vb2

Vb3Vb4

Vc1Vc2

Vc3

Vc4

K1

K3

K2

K4

Va

Vb2

Va2 Va4

VbVc

Va1

Vb1

Vb3Vb4Vc1

Vc2

Vc3

Vc4

Va3

240240

240

240

240

240

240

240

240240

240

240

240

240240

Va1 = K1Va 00 - K2 Vb-1200

Va2 = K3Va 00 - K4Vb-1200

Va3 = K1Va00 - K2Vc 1200

Va4 = K3Va 00 - K4Vc1200

Va=V00, Vb=V-1200 , Vc = V1200

Va1 = V 240 , Vb1 = V-960, Vc1 = V1440

Va2 = V 480, Vb2 = V-720, Vc2 = V1680

Va3 = V -240, Vb3 = V-1440, Vc3 = V960

Va4 = V -480, Vb4 = V-1680, Vc4 = V720

5555

a1

A

B

C


Cd

-

Zs

Zs

Zs

+

Vdc

ia

ib

ic

+

IPT

b1

c1

a2

b2

c2

a3

b3

c3

a4

b4

c4

Vb1

Va

Va1

VbVc

N

Va2Va3

Va4

Vb2

Vb3Vb4Vc1Vc2

Vc3

Vc4

Autotransformer

a

b

c

IPT

+

+

+

+

Load

i

i1

i2

i3

i4

i5

5656

Magnetics Rating = 76%

THD = 2.38%

5757

Three-Phase Unidirectional 12-Pulse Converter

va

vb

vc

ia

ib

ic

La

Lb

Lc

a2

c2

a1

c1

b1o15

b2 o15

Autotransformer

Li1

Li2

vdc

Load

idc

a

bc

a2c2

c1

b1

b2

a1

Cd

Extended Delta Connection Based 12-Pulse AC-Extended Delta Connection Based 12-Pulse AC-DC ConverterDC Converter

5858


o20

o20

Autotransformer

va

vb

vc

ia

ib

ic

La

Lb

Lc

o0

Li1

vdc

Load

idc

Li2

Cd

Extended Delta Connection Based Extended Delta Connection Based 18-Pulse AC-DC Converter 18-Pulse AC-DC Converter

5959

Extended Delta Connection BasedExtended Delta Connection Based 18-Pulse AC-DC Converter 18-Pulse AC-DC Converter

LOAD

6060

Harmonic Spectrum of 18-pulse AC-DC Harmonic Spectrum of 18-pulse AC-DC converterconverter

6161

A A six-pulse diode-bridgesix-pulse diode-bridge fed vector-controlled induction fed vector-controlled induction motor drive (VCIMD) and the controller.motor drive (VCIMD) and the controller.

Zs

Zs

Zs

isa

isb

isc

+

-

6- pulse rectifier

Cd Vdc

Ld

IGBT Based Inverter

~~~

PWM Current

Controller

Field Orientation

and Reference Current

Generation

Estimator for

idm* , iqm* , ω2

*

LimiterPI Speed

Controller

Field Weakening

3 Phase IM

3- Phase AC Mains

ima

imb

imc

ima

imb

ima*

imb*

imc*

idm*

iqm*

ω2*

imr

T T*

ωr

ωrωrωr

*

6262

Dynamic response of 6-pulse diode rectifier fed VCIMD with load perturbation--supply phase voltage VA, source current isA, motor currents

Iabc, speed wr, developed electromagnetic torque Te and DC link voltage Vdc.

6363

Input current waveform and harmonic spectrum of 6-pulse AC-DC converter at full-load.

6464

Twelve-pulse AC-DC converter based on fork-transformer configuration.

3-phase AC

Mains

~~~

iA LOAD

+

-

K1

K2

Vdc

idc

K3

6565

Three-phase supply voltage applied to the input of autotransformer as

0sc

0sb

0sa 120VV ,120VV ,0VV

K1+ K2=1

Output voltages of this configuration are expressed as

b3a1a1 VKVKV

c3a1a2 VKVKV

K1=0.8165, K2= 0.1835, K3= 0.2988

6666

Non-Isolated fork-connection based 24-Pulse AC-DC converterNon-Isolated fork-connection based 24-Pulse AC-DC converter

IPR

3-phase AC

Mains

~~~

iA LOAD

+

-

VDC

iDC

DB1

DB2

DB3

DB4

6767

a

bc

a1

a2a3

a4

b1

b2

b3b4c1c2

c3

c4

K4

K7

K6

K5

nVA

VB

VC

DB1

DB2

DB3

DB4

K8

7.5°

7.5°

7.5° 7.5°

a

bc

n

a1

7.5°7.5°

15° 15°

15°15°

a2 a3a4

b1

b2

b3

b4c1

c2

c3

c4

Phasor representation of transformer for 24-pulse AC-DC converter having fork connected windings.

Winding arrangement of transformer for 24-pulse AC-DC converter having fork connected windings.

6868

0sc1

0sb1

0sa1 217.5VV ,5.97VV ,5.22VV

0sc2

0sb2

0sa2 232.5VV ,5.112VV,5.7VV

0sc3

0sb3

0sa3 247.5VV ,5.127VV,5.7VV

0sc4

0sb4

0sa4 262.5VV ,5.142VV ,5.22VV

The four sets of required voltages for the converters DB1 to DB4 are:

6969

b6b5a4a1 VKVKVKV

a7b5a4a2 VKVKVKV

15-VV a2a3

45-VV a1a4

K8 = 1 - K4

K4=0.7029, K5= 0.1507, K6= 0.2912, K7= 0.2132, K8 =0.2971

The output voltages can be expressed as follows:

7070

Matlab model of 24-pulse AC-DC converter with VCIMD load.

7171

15Out43

14Out33

13Out42

12Out32

11Out41

10Out31

9Out23

8Out22

7Out13

6Out12

5

In3

4In2

3Out21

2Out11

1In1 1+

1

+2

2

+3

3

+4

4

+5

5

+6

6

+7

7

+8

8

PhC

1+

1

+2

2

+3

3

+4

4

+5

5

+6

6

+7

7

+8

8

PhB

1+

1

+2

2

+3

3

+4

4

+5

5

+6

6

+7

7

+8

8

PhA

Matlab model of auto-transformer for the 24-pulse AC-DC converter system simulation.

7272

-400-200

0200400

VA

(V)

0

I ac(A

)

-50

0

50

I abc (

A)

0

100200

Time(sec)

wr(r

ps)

-50

050

100150

T e(N-m

)

0.05 0.1 0.15 0.2 0.25 0.30

500

Time (sec.)

Vdc

(V

)

Dynamic response of 24-pulse diode rectifier fed VCIMD with load perturbation----- supply phase voltage VA, source current isA, motor currents Iabc, speed wr, developed electromagnetic torque Te and DC link voltage

7373

0.76 0.77 0.78 0.79 0.8-40

-20

0

20

40

I A (

A)

time (s)

0 12 24 36 48 600

20

40

60

80

100

THD = 3.221%

% M

agni

tude

Harmonic order


7474

Topo-Topo-logylogy

LoadLoad AC MainsAC MainsCurrent ICurrent I

acac

(A)(A)

% THD of% THD ofIIacac

atat

DistortionDistortionFactorFactor

DFDF

DisplacementDisplacementPower FactorPower Factor

DPFDPF

PowerPowerFactorFactor

PFPF

DC VoltageDC Voltage(V)(V)

LightLight FullFull LightLight FullFull LightLight FullFull LightLight FullFull LightLight FullFull LightLight FullFull

LoadLoad LoadLoad LoadLoad LoadLoad LoadLoad LoadLoad LoadLoad LoadLoad LoadLoad LoadLoad LoadLoad

6-6-pulsepulse

10.5810.58 8.7018.701 19.1219.12 74.6874.68 31.2431.24 0.91100.9110 0.94910.9491 0.97980.9798 0.97680.9768 0.89260.8926 0.92710.9271 552.9552.9 542.8542.8

12-12-pulsepulse

5.2245.224 8.5788.578 18.8718.87 9.6979.697 8.988.98 0.99460.9946 0.99460.9946 0.98930.9893 0.98980.9898 0.98400.9840 0.98450.9845 555.7555.7 549.4549.4

24-24-pulsepulse

3.0363.036 8.3788.378 18.7418.74 3.9743.974 3.2213.221 0.99900.9990 0.99910.9991 0.99310.9931 0.98910.9891 0.99210.9921 0.98820.9882 578.2578.2 570.7570.7

COMPARISON OF POWER QUALITY PARAMETERS OF DIFFERENT AC-DC CONVERTERS.

7575

Comparison of power quality parameters of12-pulse and 24-pulse AC-DC converters with varying load

Topology

Topology

LoadLoad THD of THD of VVacac

(%)(%)

AC AC Mains Mains CurrenCurrent It Iacac

(A)(A)

THD of THD of

IIacac(%)(%)

Distort-Distort-ion ion

Factor, Factor, DFDF

DisplaceDisplacement ment

Power Power Factor, Factor,

DPFDPF


PFPF

DC DC Voltage Voltage

(V)(V)

Load Load CurreCurrent Int Idcdc

(A)(A)

Ripple Ripple FactorFactor, RF , RF (%)(%)

12-pulse12-pulse

20%20% 2.8512.851 8.5788.578 9.6979.697 0.99460.9946 0.98930.9893 0.98400.9840 555.7555.7 10.2810.28 0.0060.006

40%40% 3.4943.494 11.0311.03 9.5339.533 0.99480.9948 0.98970.9897 0.98460.9846 554.2554.2 13.2113.21 0.0020.002

60%60% 3.9813.981 13.5813.58 9.3639.363 0.99480.9948 0.98990.9899 0.98480.9848 552.6552.6 16.4816.48 0.0040.004

80%80% 4.6744.674 16.2216.22 9.1799.179 0.99460.9946 0.99000.9900 0.98470.9847 551.0551.0 19.8519.85 0.0030.003

100%100% 5.2245.224 18.8718.87 8.988.98 0.99460.9946 0.98980.9898 0.98450.9845 549.4549.4 23.2423.24 0.0020.002

24-pulse24-pulse

20%20% 2.0282.028 8.3788.378 3.9743.974 0.99900.9990 0.99310.9931 0.99210.9921 578.2578.2 10.2510.25 0.0000.00022

40%40% 2.2862.286 10.7310.73 3.7633.763 0.99880.9988 0.99220.9922 0.99100.9910 576.4576.4 13.1413.14 0.0000.00011

60%60% 2.5502.550 13.3113.31 3.5563.556 0.99920.9992 0.99100.9910 0.99020.9902 574.5574.5 16.3316.33 0.0020.002

80%80% 2.7852.785 16.0016.00 3.3763.376 0.99900.9990 0.99010.9901 0.98910.9891 572.7572.7 19.6619.66 0.0030.003

100%100% 3.0363.036 18.7418.74 3.2213.221 0.99910.9991 0.98910.9891 0.98820.9882 570.7570.7 23.0423.04 0.0020.002

7676

MATLAB model of the proposed autotransformer for 24-pulse AC-DC converter

Topology

Load AC MainsCurrent Iac

(A)

% THD ofIac

at

DistortionFactor

DF

DisplacementPower Factor

DPF

PowerFactor

PF

DC Voltage(V)

Light Full Light Full Light Full Light Full Light Full Light Full

Load Load Load Load Load Load Load Load Load Load Load

6-pulse

10.58 8.701 19.12 74.68 31.24 0.9110 0.9491 0.9798 0.9768 0.8926 0.9271 552.9 542.8

12-pulse

5.224 8.578 18.87 9.697 8.98 0.9946 0.9946 0.9893 0.9898 0.9840 0.9845 555.7 549.4

24-pulse

3.036 8.378 18.74 3.974 3.221 0.9990 0.9991 0.9931 0.9891 0.9921 0.9882 578.2 570.7

7777

Input current waveform of 12-pulse AC-DC converters at light load and its harmonic spectrum

7878

Dynamic response of 24-pulse diode rectifier fed VCIMD with load perturbation--supply phase voltage VA, source current isA, motorcurrents Iabc, speed wr, developed electromagnetic torque Te and DC link voltage.

7979

Input current waveforms of 24 pulse AC-DC converter at full load and its harmonic spectrum.

8080

Comparison of magnetic ratings in different AC-DC converters

Sr.Sr.No.No.

TopologyTopology Main Main Transformer Transformer

ratingrating(% of load)(% of load)

Interphase Interphase transformer ratingtransformer rating

(% of load}(% of load}

Total Total magnetic rating magnetic rating

(% of load)(% of load)

11 12-pulse12-pulse 28.6828.68 7.507.50 36.1836.18

22 24-pulse24-pulse 49.249.2 7.367.36 56.5656.56

8181

POLYGON CONNECTED AUTOTRANSFORMER BASED 24-PULSE AC-DC CONVERTER

K2

K1

K3K4

Va

VbVc

Va1

Va2

Va3

Va4

Vb1

Vb2

Vb3

Vb4

Vc1

Vc2

Vc3

Vc4

A

BC

K1 K2

K3K4

N

E

Va

Vb2

Va2 Va4

VbVc

7.507.50

22.5022.50

Va1

Vb1

Vb3

Vb4

Vc1

Vc2

Vc3

Vc4

Va3

8282

Va1 = Va - K1 Vbc + K2 Vca (1) Va2 = Va1 - K3 Vbc + K4 Vca (2)Va3 = Va + K1 Vbc - K2 Vab (3) Va4 = Va3 + K3 Vbc - K4 Vab (4)Assume the following set of voltages:Va=V00, Vb=V-1200 , Vc = V1200 (5)Va1 = V 7.50 , Vb1 = V-112.50, Vc1 = V127.50 (6)Va2 = V 22.50, Vb2 = V-97.50, Vc2 = V122.50 (7)Va3 = V -7.50, Vb3 = V-127.50, Vc3 = V112.50 (8)Va4 = V -22.50, Vb4 = V-142.50, Vc4 = V97.50 (9)

K1 =0.07249, K2 = 0.00576,

K3 = 0.123 and K4 = 0.04509

DESIGN

8383

K1 cos 600 +K2 + K3 cos 600 +K4 + N + K1 cos 600 + K2 + K3 cos 600 = 1 (10) 2K2 +2K4 +K1 + K3 + N = 1 (11) N= 0.6987 (12)

Va1 =Va – 0.071Vbc + 0.00855Vca (13)Va2 =Va3 – 0.123 Vbc + 0.04509 Vca (14)

Va3 =Va + 0.071 Vbc – 0.00855 Vab (15)Va4 =Va + 0.123 Vbc – 0.04509 Vab (16)

8484

IGBT Based Inverter

A

B

C3 Phase, 415V,

50 Hz


Cd

-

+

Autotransformer

Zs

Zs

Zs

3 Phase,VCIMD

+Vdc

IPT

isa

isb

isc

Ld

+

IPT

+

+

a1

b1

c1

a2

b2

c2

a3

b3

c3

a4

b4

c4

Va

VbVc

A

BC

8585

Va

Vb

Va1

Va2

Va3

Va4

Vb1'

Vb2'

Vb3'

Vb4'

AK1

K2K3

K4

K1'

K2'

K4'

7.50

7.50

22.50

22.50

7.50

K3'

22.50

22.50

K1’= 0.0546

K2’= 0.0347

K3’=0.1175

K4’= 0.04314

N’ = 0.6722

8686

8787

Dynamic response of 6-pulse diode rectifier fed VCIMD with load perturbation.

8888

8989Dynamic response of 24-pulse ac-dc converter based proposed harmonic mitigator fed VCIMD with load perturbation.

9090

Magnetics Rating = 27.5%

9191

Load Load (%)(%)

THD (%)THD (%) CF CF of Iof I

ss

DFDF DPFDPF PFPF VVdcdc

(V)(V)IIss VVtt

2020 5.225.22 1.761.76 1.431.43 .998.998 .989.989 .988.988 557557

4040 4.654.65 1.901.90 1.431.43 .999.999 .990.990 .989.989 553553

6060 4.414.41 2.312.31 1.431.43 .999.999 .989.989 .989.989 551551

8080 4.054.05 2.512.51 1.441.44 .999.999 .988.988 .988.988 547547

100100 3.203.20 2.732.73 1.441.44 .999.999 .988.988 .988.988 546546

9292

Comparison of power quality indices of a VCIMD fed from different converters

Sr. Sr. NoNo

TopoTopologylogy

THD THD of Vof V

ss

(%)f(%)fFLFL

Supply Current Supply Current IIss (A) (A)

Total Total Harmonic Harmonic

Distortion of Distortion of IIss (%) (%)

Distortion Distortion FactorFactor

Displacement Displacement FactorFactor

Power FactorPower Factor DC Link DC Link Voltage(V)Voltage(V)

AverageAverage

FLFL LLLL(20%)(20%)

FLFL LLLL(20%)(20%)

FLFL LLLL(20%)(20%)

FLFL LLLL(20%)(20%)

FLFL LLLL(20%)(20%)

FLFL LLLL(20%)(20%)

1.1. AA 6.536.53 12.5212.52 4.024.02 30.730.7 57.257.2 .955.955 .868.868 .980.980 .959.959 .937.937 .833.833 545545 556556

2.2. BB 2.802.80 10.6210.62 2.332.33 3.263.26 5.175.17 .998.998 .999.999 .989.989 .988.988 .987.987 .987.987 570570 578578

3.3. CC 2.732.73 10.5910.59 2.312.31 3.203.20 5.225.22 .998.998 .999.999 .989.989 .988.988 .988.988 .988.988 546546 557557

9393

An Isolated Fork Connected Transformer Based 24-Pulse AC-

DC Converter

9494

Six-pulse diode bridge rectifiers with delta and star-Six-pulse diode bridge rectifiers with delta and star-connected transformers supply are commonly used.connected transformers supply are commonly used.

3-phase AC

Mains

~~~

iA

1 : a

LOAD

Six-Pulse Diode Bridge

i DC

VDC

+

-

A 6-pulse AC-DC converter using delta/star transformer.

9595

iA

1:a

Load

Six- Pulse Diode Bridge

Vdc

+

-

idc

~~~

Delta/star Transformer

3- phase AC

Mains

A 6-pulse AC-DC converter using delta/star transformer

Twelve-pulse AC-DC converter based on fork-transformer configuration-

3-phase AC

Mains

~~~

iALOAD

+

-

VDC

iDC

1 : a

K1K2

9696

IPR

3-phase AC

Mains

~~~

iA LOAD

+

-

VDC

iDC

1 : aDB1

DB2

DB3

DB4

Twenty four-pulse AC-DC converter based on fork-transformer configuration-

9797

Delta/fork transformer winding arrangement for 24-pulse AC-DC converter.

A

BC

Primary

a1

Secondary

a2a3

a4

b1

b2

b3b4c1

c2

c3

c4

K1

K4

K3K2

n

VA

VB

VC

DB1

DB2

DB3

DB4

9898

Phasor representation of transformer for 24-pulse Phasor representation of transformer for 24-pulse AC-DC converter having fork connected secondary AC-DC converter having fork connected secondary

winding winding

7.5°

7.5°

7.5°

7.5°

Va

VbVc

n

a1

Secondary

7.5°7.5°

15° 15°

15° 15°

a2 a3

a4

b1

b2

b3

b4c1

c2

c3

c4

A

N

BC

Primary

9999

0sC

0sB

0sA 120VV ,120VV ,0VV

Three-phase supply voltage applied to the primary of transformer as

Secondary phase voltages for the transformer with transformation ratio ‘a’ (a= Va/VA)

Four sets of required voltages for the converters DB1 to DB4 are

CcBbAa VaV ,VaV ,VaV

0sc1

0sb1

0sa1 217.5VV ,5.97VV ,5.22VV

0sc2

0sb2

0sa2 232.5VV ,5.112VV,5.7VV

0sc3

0sb3

0sa3 247.5VV ,5.127VV,5.7VV

0sc4

0sb4

0sa4 262.5VV ,5.142VV ,5.22VV

100100

K1=0.7029, K2= 0.15072, K3= 0.29116, K4= 0.21315

b3b2a1a1 VKVKVKV

a4b2a1a2 VKVKVKV

15-VV a2a3

45-VV a1a4 45-VV a1a4

45-VV a1a4

kVA rating = 0.5 ∑ (Vwinding I winding)

TUF= PDC/∑ (Vsec . Isec)

101101

MATLAB model of the 24-pulse AC-DC converter

v+-

Vin2

v+

-

Vin1

In1

In2

In3

Out11

Out21

Out12

Out13

Out22

Out23

Out31

Out41

Out32

Out42

Out33

Out43

Fork24-pulseISO-Xer

Transformer

LOAD

Scope2

Scope

12

LT3

12

LT2

12

LT1

12

LT

i+ -

Iin3

i+ -

Iin2

i+ -

Iin1

i+ -

Iin

A

B

C

+

-

DB4

A

B

C

+

-

DB3

A

B

C

+

-

DB2

A

B

C

+

-

DB1

N

A

B

C

3-Ph

vA

iA

iB

iC

102102

MATLAB model of the proposed transformer for 24-pulse AC-DC converter

15Out43

14Out33

13Out42

12Out32

11Out41

10Out31

9

Out23

8Out22

7Out13 6

Out12

5

In34

In2

3Out21

2Out11

1In1

1+

1

+2

2

+3

3

+4

4

+5

5

+6

6

+7

7

+8

8

PhC

1+

1

+2

2

+3

3

+4

4

+5

5

+6

6

+7

7

+8

8

PhB

1+

1

+2

2

+3

3

+4

4

+5

5

+6

6

+7

7

+8

8

PhA

103103

Comparison of power quality parameters of12-pulse and 24-pulse AC-DC converters with varying

load

TopologyTopology LoadLoad THD of THD of VVacac (%) (%)

AC Mains AC Mains Current ICurrent I

acac

(A)(A)

THD of THD of I I

acac(%)(%)Distortion Distortion Factor, DFFactor, DF

Displacement Displacement Power Factor, Power Factor,

DPFDPF


PFPF

DC DC Voltage Voltage

(V)(V)

Load Load Current Current IIdcdc (A) (A)

Ripple Ripple Factor, Factor, RF (%)RF (%)

12-Pulse12-Pulse

40%40% 2.0052.005 11.3111.31 10.3710.37 0.99450.9945 0.99150.9915 0.98600.9860 297.8297.8 26.4726.47 1.0281.028

60%60% 2.6562.656 16.7716.77 9.9279.927 0.99480.9948 0.99050.9905 0.98530.9853 295.5295.5 39.4039.40 0.90520.9052

80%80% 3.2173.217 22.1322.13 9.6869.686 0.99480.9948 0.98900.9890 0.98390.9839 293.2293.2 52.1252.12 0.85390.8539

100%100% 3.6793.679 27.4227.42 9.249.24 0.99500.9950 0.98760.9876 0.98270.9827 290.9290.9 64.6464.64 0.82870.8287

24-Pulse24-Pulse

40%40% 1.5051.505 11.3411.34 4.4614.461 0.99890.9989 0.99150.9915 0.99040.9904 299.3299.3 26.6026.60 0.32320.3232

60%60% 1.9881.988 16.8816.88 4.5424.542 0.99880.9988 0.99210.9921 0.99090.9909 297.8297.8 39.739.7 0.35540.3554

80%80% 2.3652.365 22.3122.31 4.1434.143 0.99890.9989 0.99250.9925 0.99140.9914 296.3296.3 52.6752.67 0.38080.3808

100%100% 2.7012.701 27.7327.73 2.7042.704 0.99870.9987 0.99230.9923 0.99100.9910 294.8294.8 65.565.5 0.44870.4487

104104

Comparison of power quality parameters of Comparison of power quality parameters of the 12-Pulse and 24-Pulse AC-DC converters the 12-Pulse and 24-Pulse AC-DC converters

with 6-Pulse AC-DC Converter with 6-Pulse AC-DC Converter

Topology

Topology

LoadLoad AC MainsAC MainsCurrent ICurrent I

ac ac (A)(A)% THD of% THD of

IIacac at atDistortionDistortionFactor DFFactor DF

DisplacementDisplacementPower Factor Power Factor

DPFDPF

PowerPowerFactor PFFactor PF


LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFull

6-pulse6-pulse

4.724.72 5.8945.894 27.9927.99 27.6427.64 24.1324.13 0.9630.963 0.9710.971 0.9940.994 0.9750.975 0.9580.958 0.9470.947 30033003 290.6290.6

12-pulse12-pulse

3.6793.679 5.7565.756 27.4227.42 10.8110.81 9.249.24 0.9930.993 0.9950.995 0.9900.990 0.9870.987 0.9840.984 0.9820.982 300.2300.2 290.9290.9

24-pulse24-pulse

2.7012.701 5.7775.777 27.7327.73 4.874.87 2.702.70 0.9980.998 0.9980.998 0.9840.984 0.9920.992 0.9830.983 0.9910.991 300.8300.8 294.8294.8

105105

Waveforms of 6-pulse AC-DC converter at full-load.

Input current waveform of 6-pulseAC-DC converter at full-load and its harmonic spectrum.

106106



107107

Input and output voltage and currentwaveforms of 24-pulse AC-DC converter at full load.

Input current waveforms of 24 pulse AC-DC converter at full loadand its harmonic spectrum.

108108


Sr.Sr.No.No.

TopologyTopology Main Main TransforTransfor

mer mer ratingrating


Interphase Interphase transformer transformer

ratingrating(% of load}(% of load}

Total Total magnetic magnetic

rating rating (% of (% of load)load)

11 6-pulse6-pulse 102.73102.73 -- 102.73102.73

22 12-pulse12-pulse 108.78108.78 8.088.08 116.86116.86

33 24-pulse24-pulse 106.63106.63 7.367.36 113.99113.99

109109

A 36-Pulse AC-DC Converter for Line Current Harmonic Reduction

110110

iA

1:a

Load

Six- Pulse Diode Bridge

Vdc

+

-

idc

~~~

Delta/star Transformer

3- phase AC

Mains

A 6-pulse AC-DC converter using delta/star transformer

Proposed Fork

Based36-pulse

Transfor-mer

3-Phase AC

Mains

18 Pulse Diode Bridge Rectifier,

DB1

18 Pulse Diode Bridge Rectifier,

DB2

~~~

Zs

Zs

Zs

iA

iB

iC

Ld

IPR

IPR

+

-

LoadVdc

B11

B19

B21

B29

Proposed delta/fork transformer based 36-pulse AC-DC converter.

111111

VB

VA

K1

K2K3

K4

K5

K6

A

BC

Primary

a1

Secondary

a2a3 a4

b1

b2

b3b4

c1

c2c3

c4

n

VC

DB1

DB2

a5

a6

b5

b6

c5

c6

B11B12

B13

B14

B15

B16

B17

B18

B19

B21B22

B23

B24

B25

B26

B27B28

B29

iAB

iBC

iCA

iA

iB

iC

50

50

300

300

300

300300

300

300

300

300

100

100

100

100

100

50

5050

50

100

VB11

VB21

VB12

VB13

VB14

VB15

VB16

VB17

VB18

VB19

VB22

VB23

VB24

VB25

VB26

VB27

VB28

VB29

VsBVsC

VsAVsA= VR

Graphical representation of delta/polygon transformer secondary for 36-pulse AC-DC converter and phasor diagram.

Delta/fork transformer winding arrangement for 36-pulse AC-DC converter.

112112

527VV ,523VV ,195VV

,155VV,115VV ,75VV

,35VV ,5VV ,45VV

RB19RB18RB17

RB16RB15RB14

RB13RB12RB11

528VV ,524VV ,205VV

,165VV,125VV ,85VV

,45VV ,5VV ,35VV

RB29RB28RB27

RB26RB25RB24

RB23RB22RB21

)VKK(VKV sB54sA1B11

VK)VKK(V sB4sA31B21

VKV)KK(V sB6sA21B12

sC6sA21B22 VKV)KK(V

VK)VKK(V sC4sA31B13

)VKK(VKV sC54sA1B23

0.1006K , 1542.0K

0.6623,K 0.1891,K 0.6471,K 0.2988,K

65

4321

113113

v+-

Vab2

v+-

Vab1

LOAD

Scope2

Scope1

i+-

Iin3

i+-

Iin2i+-

Iin1

i+-

Iin

Conn1

Conn2Conn3

IPR2

Conn1

Conn2Conn3

IPR

C1

C2

C3

C4

C5

C6

C7

C8

C9

C10

C11

D3

C1

C2

C3

C4

C5

C6

C7

C8

C9

C10

C11

D1

In1

In2

In3

Out1

Out2

Out3

Out4

Out5

Out6

Out7

Out8

Out9

OutB1

OutB2

OutB3

OutB4

OutB5

OutB6

OutB7

OutB8

OutB9

Fork36pulse

Xer

36-pulse Fork Xer

N

A

B

C

3-Ph Source

MATLAB model of the 36-pulse AC-DC converter

114114

21

OutB9

20

OutB8

19

OutB7

18

OutB6

17

OutB5

16

OutB4

15

OutB3

14

OutB2

13

OutB1

12

Out9

11

Out8

10

Out7

9

Out6

8

Out5

7

Out4

6

Out3

5

Out2

4

Out1

3

In32

In2

1

In11+

1

2+

2

3+

3

4+

4

5+

5

6+

6

7+

7

+8

8

+9

9

+10

10

+11

11

PhC

1+

1

2+

2

3+

3

4+

4

5+

5

6+

6

7+

7

+8

8

+9

9

+10

10

+11

11

PhB

1+

1

2+

2

3+

3

4+

4

5+

5

6+

6

7+

7

+8

8

+9

9

+10

10

+11

11

PhA

MATLAB model of the proposed transformer for 36-pulse AC-DC converter

115115

LoadLoad THD THD VVacac

(%)(%)

AC AC Mains Mains

Current Current IIacac (A) (A)

THD of THD of

IIacac(%)(%)

Distortion Distortion Factor,Factor,

DFDF

DisplaceDisplace-ment -ment

Factor,Factor,DPFDPF

Power Power Factor,Factor,

PFPF

DC DC VoltagVoltage (V)e (V)


Ripple Ripple Factor (%)Factor (%)

20%20% 0.75710.7571 5.7875.787 3.013.01 0.99950.9995 0.99840.9984 0.99790.9979 302.9302.9 13.4613.46 0.23770.2377

40%40% 1.0741.074 11.4611.46 2.1692.169 0.99970.9997 0.99720.9972 0.99690.9969 301.8301.8 26.8326.83 0.32790.3279

50%50% 1.1551.155 14.2814.28 1.8551.855 0.99980.9998 0.99670.9967 0.99650.9965 301.3301.3 33.4833.48 0.37530.3753

60%60% 1.1931.193 17.0917.09 1.6051.605 0.99980.9998 0.99620.9962 0.99600.9960 300.8300.8 40.1040.10 0.42230.4223

80%80% 1.2101.210 22.6822.68 1.3141.314 0.99990.9999 0.99510.9951 0.99500.9950 299.6299.6 53.2753.27 0.52170.5217

100100%%

1.2141.214 28.2128.21 1.1971.197 0.99980.9998 0.99370.9937 0.99350.9935 298.4298.4 66.3066.30 0.62410.6241

Comparison of power quality parameters of proposed 36-pulse AC-DC converters with varying load

116116

Comparison of power quality parameters of Comparison of power quality parameters of the 36-Pulse AC-DC converters With 6-Pulse the 36-Pulse AC-DC converters With 6-Pulse AC-DC Converter at full-load and light load AC-DC Converter at full-load and light load

TopologTopologyy

%THD%THDVVacac

% THD of % THD of IIacac, at, at

Distortion Distortion FactorFactor

DisplacemeDisplacement Factornt Factor

Power Power FactorFactor


FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

6-pulse6-pulse 4.0564.056 24.8124.81 27.9327.93 .9815.9815 .9943.9943 .9698.9698 .9630.9630 .9519.9519 .9575.9575 279.2279.2 294.4294.4

36-pulse36-pulse 1.2141.214 1.1971.197 3.013.01 .9998.9998 .9995.9995 .9737.9737 .9984.9984 .9935.9935 .9979.9979 298.4298.4 302.9302.9

117117

The instantaneous values of input phase voltage (vA), input AC mains current (iA), primary winding currents (iAB and iCA), winding-currents of secondary (iK1 to iK6), a bridge output current (idc1) of 36-pulse AC-DC converter.

118118

Input current waveform of 6-pulse AC-DC converter at light-load andits harmonic spectrum

Input current waveform of 6-pulse AC-DC converter at full-load andits harmonic spectrum

Input and output voltage and current waveforms of 36-pulse AC-DC converter at light load


119119

Input and output voltage and current waveforms of 36-pulse AC-DC converter at full load.

Input current waveforms of 36 pulse AC-DC converter at full load and its harmonic spectrum.

120120

Test result showing input power, voltage along with current waveforms and input current harmonic spectrum at (a) light load and (b) full-load.

121121

Sr.Sr.No.No.

TopologyTopology Main Transformer Main Transformer ratingrating


IPTIPT ratingrating(% of (% of load)load)

Total Total rating of rating of magneticsmagnetics

,,(% of load)(% of load)

11 6-pulse6-pulse 108.0108.0 -- 108.0108.0

22 36-36-pulsepulse

124.2124.2 0.850.85 125.0125.0


122122

LoadLoad(kW)(kW)

THD VTHD Vacac

(%)(%)AC Mains AC Mains

Current Current IIacac (A) (A)

THD of THD of I Iacac

(%)(%)

DPFDPF PFPF VVdcdc

(V)(V)IIdcdc

(A)(A)

1.211.21 1.301.30 3.053.05 2.32.3 1.01.0 0.9990.999 168.6168.6 7.2567.256

2.162.16 1.401.40 5.385.38 2.52.5 1.01.0 0.9990.999 160.9160.9 12.8612.86

3.083.08 1.301.30 7.797.79 2.22.2 1.01.0 0.9990.999 151.4151.4 18.4018.40

4.094.09 1.301.30 10.2810.28 2.12.1 1.01.0 0.9980.998 143.7143.7 24.2124.21

5.295.29 1.301.30 13.2913.29 2.12.1 1.01.0 0.9960.996 133.7133.7 31.0931.09

6.026.02 1.201.20 15.2715.27 2.02.0 1.01.0 0.9960.996 127.8127.8 35.3735.37

Test results showing power quality parameters of 36-pulse AC-DC converter

123123

The propose 36-pulse AC-DC converter is realized by three 2.2kVA, single-phase transformers and the design details are as follows:

Flux Density: 0.8Tesla, Current Density: 2.3A/mm2, Turns per volt: 0.88E-Laminations: Length=23.5cm, Width=16cmI-Laminations: Length=23.5cm, Width= 4cmEffective Area of cross-section of core=58cm2 (7.6 cm X 8.6cm)

124124

Transformer winding details WindingNumber of turns Gauge of wire (SWG)

Winding voltageWinding voltage No. of No. of TurnsTurns

Gauge of Wire Gauge of Wire (SWG)(SWG)

VVACAC 365365 1717

KK11*V*VRR 3131 1515

KK22 *V *VRR 6868 1717

KK33* V* VRR 2020 1717

KK44 *V *VRR 69.569.5 1717

KK55* V* VRR 1616 1717

KK66* V* VRR 10.510.5 1717

125125

T-Connected Isolated TransformerT-Connected Isolated TransformerBased AC-DC ConverterBased AC-DC Converter

126126

A Six-Pulse A Six-Pulse T-ConnectedT-Connected AC-DC Converter AC-DC Converter

LOAD

Six-Pulse Diode Bridge

1:a13-phase AC

Mains

~~~

VA

VBVC

iA

iB

iDC

VDC

+

-iC

TSTP

MS2MP1MP2 MS1

127127


128128


0.05 0.06 0.07 0.08

-45

0

45

I A (

A)

time (s)

0 12 24 36 48 0

20

40

60

80

100

THD = 23.89%

% M

agni

tude

Harmonic Order

129129

Twelve-pulse AC-DC converter based on T-transformer configuration.

3-phase AC

Mains

iDC

1:a2

~~~

iA

iB

iC

VA

VBVC

LOAD

+

-

VDC

IPR

130130

Connection diagram of T-connected transformer for isolated Connection diagram of T-connected transformer for isolated 24-pulse AC-DC converter. 24-pulse AC-DC converter.

iDC

1:a2

3-phase AC

Mains

~~~

iA

iB

iC

VA

VBVC

LOAD

+

-

VDC

IPR

ZSBT

D1 D2

NA

NBVm

131131

Winding arrangement and phasor representation of transformer for 12 and 24-pulse AC-DC converter having T-connected windings.

TP1

MP1MP2

A

N

BC

Primary

TS1

TS2

TS3

TS5

TS4

TS6

MS1MS2

MS3

MS4MS7

MS6 MS5

MS8

15° 15°

15°

15°

15°15°

a

bc

n

a’ a”

b”

b’c”

c’

Secondary

132132

Design of Transformer for 12-Pulse and 24-Pulse AC-DC ConvertersThe voltages across primary winding of the T-connected transformers VTP1= 0.866 VLP VMP1= VMP2=0.5 VLPThe secondary voltage produced is related to primary voltage by the transformation ratio. a3 = VLP / VLSThe secondary produces two sets of three-phase voltages that are displaced from respective primary voltages by +15° and -15°. The various winding voltages in terms of secondary voltage VLS can be determined from Fig. 3 by following relations.VTS1= K1*VLSVTS2= K2*VLSVTS3= VTS3= K3*VLSVTS5= VTS6= K4*VLSVMS1= VMS2= K5*VLSVMS3= VMS8= K6*VLSVMS4= VMS7= K7*VLSVMS5= VMS6= K8*VLS

133133

The values of constants K1 to K8 are:K1=0.5577, K2=0.2887, K3=0.1392, K4=0.1196,K5=0.1494, K6=0.0577, K7=0.0917, K8=0.4082

134134

MATLAB model of T-transformer based 24-pulse AC-DC converter

135135

Matlab model of T-transformer for the 24-pulse AC-DC converter system simulation.

136136

Waveforms of 12-pulse T-connected AC-DC converter at full-load - supply phase voltage VA, supply line currents IA, IB and IC , output DC link current (IDC) and voltage (VDC).

137137

Input current waveform and harmonic spectrum of 12-pulse T-connected AC-DC converter at full-load.

0.04 0.05 0.06 0.07 0.08

-50

0

50

I A (

A)

time (s)

0 12 24 36 480

20

40

60

80

100

THD = 6.142%

% M

agni

tude

Harmonic Order

138138

Waveforms of 24-pulse T-connected AC-DC converter at full-load - supply phase voltage VA, supply line currents IA, IB and IC , output DC link current (IDC) and voltage (VDC)

139139

0.05 0.06 0.07

-50

0

50

I A (

A)

time (s)

0 12 24 36 48 0

20

40

60

80

100

THD = 3.507%

% M

agni

tude

Harmonic Order

Input current waveform and harmonic spectrum of 24-pulse T-connected AC-DC converter at full-load.

140140

Comparison of Power Quality Parameters of 12-Pulse and 24-Pulse AC-DC Converters.

Topology

Topology

LoadLoad THD THD of Vof VACAC

(%)(%)

AC AC CurrenCurrent It IAA

(A)(A)

THD of THD of I IAA(%)(%)

DistortioDistortion Factor,n Factor,

DFDF

Displace-Displace-ment ment

Factor, Factor, DPFDPF

Power Power Factor Factor

PFPF

DC DC VoltagVoltage (V)e (V)


RippleRippleFactor Factor

%%

12-Pulse

12-Pulse

2020 0.8140.814 8.8208.820 9.6339.633 0.99530.9953 0.98530.9853 0.98070.9807 300.2300.2 20.0920.09 1.9551.955

4040 1.2811.281 17.0317.03 7.6127.612 0.99710.9971 0.97290.9729 0.97010.9701 298.4298.4 40.1640.16 1.8231.823

5050 1.6811.681 21.1921.19 7.4007.400 0.99710.9971 0.96820.9682 0.96540.9654 297.0297.0 49.8849.88 1.7591.759

6060 1.9131.913 25.4725.47 6.9396.939 0.99740.9974 0.97040.9704 0.96790.9679 296.7296.7 59.7459.74 1.6961.696

8080 2.3072.307 33.8733.87 6.3486.348 0.99770.9977 0.97310.9731 0.97090.9709 296.2296.2 79.4779.47 1.7251.725

100100 2.8042.804 41.8541.85 6.1426.142 0.99770.9977 0.97380.9738 0.97160.9716 295.8295.8 98.7898.78 1.7571.757

24-Pulse

24-Pulse

2020 1.0321.032 8.5838.583 5.4695.469 0.99850.9985 0.99800.9980 0.99650.9965 301.5301.5 20.1020.10 0.50620.5062

4040 1.6041.604 16.9916.99 4.7594.759 0.99880.9988 0.99690.9969 0.99570.9957 300.4300.4 40.0440.04 0.32730.3273

5050 1.8341.834 21.1721.17 4.4524.452 0.99890.9989 0.99650.9965 0.99540.9954 299.9299.9 49.9849.98 0.73680.7368

6060 2.0222.022 25.3325.33 4.2184.218 0.99890.9989 0.99610.9961 0.99500.9950 299.3299.3 59.8559.85 0.80250.8025

8080 2.3372.337 33.5733.57 3.8143.814 0.99900.9990 0.99520.9952 0.99420.9942 298.2298.2 79.5379.53 0.95860.9586

100100 2.5822.582 41.7741.77 3.5073.507 0.99910.9991 0.99450.9945 0.99360.9936 297.2297.2 99.0999.09 1.13901.1390

141141

Comparison of power quality parameters of12-pulse and 24-pulse AC-DC converters with varying load

Topology

Topology

% % THDTHD

ofofVVacac

AC MainsAC MainsCurrent ICurrent I

aa

(A)(A)

% THD of% THD ofIIaa

DistortionDistortionFactorFactor

DisplacementDisplacementFactorFactor

PowerPowerFactorFactor


LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

LightLightLoadLoad

FullFullLoadLoad

6-6-pulsepulse 4.8484.848 8.8998.899 42.3742.37 27.5627.56 23.8923.89 0.96400.9640 0.97160.9716 0.99450.9945 0.97770.9777 0.95870.9587 0.94990.9499 300.7300.7 292.7292.7

12-12-

pulsepulse 2.8042.804 8.8208.820 41.8541.85 9.6339.633 6.1426.142 0.99530.9953 0.99770.9977 0.98530.9853 0.97380.9738 0.98070.9807 0.97160.9716 300.2300.2 295.8295.8

24-24-

pulsepulse 2.5822.582 8.5838.583 41.7741.77 5.4695.469 3.5073.507 0.99850.9985 0.99910.9991 0.99800.9980 0.99450.9945 0.99650.9965 0.99360.9936 301.5301.5 297.2297.2

142142

Converter Specifications

AC Supply: 415V, 50Hz.Source impedance: Zs= j0.172 ohms (=3%)DC Load: 300V, 30kW, Ldc =1mHTransformation ratio of transformers:

6-pulse AC-DC Converter: 1: 0.5112-pulse AC-DC Converter: 1: 0.5324-pulse AC-DC Converter: 1:0.53

143143

1. Power quality is improved significantly by employing the proposed T-connected isolation transformer based 24-pulse AC-DC converter.

2. The input line current has 23rd and 25th harmonics as the dominant harmonics in 24-pulse AC-DC converter.

3. Total harmonic distortion of input current remains below 8% and power factor remains above 0.99 at varying loads.

4. It meets the requirements of IEEE-519 standard.5. Only two single-phase transformers are used.

144144

Multipulse Full Wave AC-DC Multipulse Full Wave AC-DC ConvertersConvertersIsolated Full-Wave

Multipulse AC-DC Converters

Star-connection Zigzag-connection T-connection

6-Pulse

12-Pulse

18-Pulse

24-Pulse

6-Pulse

12-Pulse

18-Pulse

24-Pulse

6-Pulse

12-Pulse

18-Pulse

24-Pulse

145145

Star Connected Multipulse Star Connected Multipulse Full Wave 6-Pulse AC-DC Full Wave 6-Pulse AC-DC

ConverterConverter

Idc

Load~~~3-phase

AC mains

ANSI 45 transformer

146146


ConverterConverter3-phase AC mains

Idc/2 Idc/2

+

-

Load

ANSI 46 transformer

147147


ConverterConverter

+

-

Load

idc

vdc

va

vb

vc

ib

ic

ia

148148


ConvertersConverters

+

-

Load

idc

vdcva

vb

vc

ib

ic

ia30°

45°

60°

15°

149149

Multipulse Controlled AC-DC Multipulse Controlled AC-DC ConvertersConverters

150150

A 48-pulse controlled AC-DC converter derived A 48-pulse controlled AC-DC converter derived from six-pulse converter by pulse multiplicationfrom six-pulse converter by pulse multiplication

Three-Phase 24-Pulse Bidirectional Mid Point Reactor Converter.

va

vb

vc

ia

ib

ic

vdc

Load

idcCp

Cq

Transformer

Transformer

151151

Pulse multiplication in series connected isolated Pulse multiplication in series connected isolated AC-DC converter using auxiliary circuitAC-DC converter using auxiliary circuit


Tr3 vdc

Load

idc

va

vb

vc

ia

ib

ic

La

Lb

Lc

Transformer

Tr2

Cp

Cq

152152

Pulse Multiplication in parallel connected bridges using Pulse Multiplication in parallel connected bridges using DC ripple reinjection TechniqueDC ripple reinjection Technique

Three-Phase 48-Pulse Bidirectional Converter

vdc

Load

va

vb

vc

ia

ib

ic

Transformer

Ld

o0

o30idc

153153

Y

LOA

D

YY L

v1

v2

I0

3-phasesupply

Pulse multiplication in 12-pulse controlled rectifier using multi-tap interphase reactor

154154

N o

N K

v SK

v YK

T K

T m

a

V M

N o

N m

v SK

v Ym

T K T m

a

V M

V y1

.

V y2

.

V y1

.

V x

.

V 2

.

V 1

.

V z2

.

V z1

.

V zn

.

q

q-

0 0

/2n

/n

/2n

V M

.

q-

V yn

.V y(n-1)

.

V yn

.V y1

.

V x

. V 2

.V 1

.

V z1

.V zn

.

qq-

0 0

/2n

/n

/2n

V y(n-1)

.

V z(n-1)

.V M

.

q

0 0

Tapped IPT

155155

Simulation for isolated 12x3-PulseControlled operationContinuous

v+-

Vin3

v+-

Vin2

v+-

Vin1

v+-

Ving

A

B

C

+

-

Univ2

g

A

B

C

+

-

Univ1

Conn1

Conn3

Conn2

Subsystem1

Step2

A

B

C

a2

b2

c2

a3

b3

c3

StarDelTr

Conn3

Conn1

Conn2

Conn4

Src&SrcX

Scope2

Scope1

RL3

RL!3

RL!2

i+-

Iin1i+ -

Iin

-K-

Gain

alpha

FiringAngle

0

Constant

c 12

Breaker

alpha_deg

A

B

C

Block

PY

PD

12plsGen

Matlab model for pulse multiplication in 12-pulse controlled rectifier using multi-tap interphase reactor

156156

0 0.05 0.1 0.15 0.2-20

-10

0

10

20

Time (s)

Cur

rent

(A),

Vol

tage

/25(

volts

)

0.15 0.16 0.17 0.18-10

-5

0

5

10

Time (s)

FFT window: 2 of 9.209 cycles of selected signal

0 20 40 600

0.05

0.1

0.15

0.2

0.25

Harmonic order

Fundamental (50Hz) = 9.214 , THD= 3.97%

Mag

Simulation resultsfor pulse multiplication in 12-pulse controlled rectifier using multi-tap interphase reactor

157157

Y

LOAD

T m

T pq

C p

C q

I0

Pulse multiplication in 12-pulse rectifier with series connected bridges for high voltage

applications

158158

Controlled Multi-pulse (12 pulse)Controlled Multi-pulse (12 pulse)

159159


160160


161161

Controlled Multi-pulse (12 pulse)Controlled Multi-pulse (12 pulse)Control CircuitControl Circuit

162162

Controlled Multi-pulse (12 pulse)Controlled Multi-pulse (12 pulse)AnalysisAnalysis

163163

Controlled Multi-pulse (12 pulse)Controlled Multi-pulse (12 pulse) Simulated Waveforms Simulated Waveforms

164164

Controlled Multi-pulse (12 pulse)Controlled Multi-pulse (12 pulse)Simulated WaveformsSimulated Waveforms

165165

Controlled Multi-pulse (12 pulse)Controlled Multi-pulse (12 pulse)Experimental waveformsExperimental waveforms

166166

Controlled Multi-pulse Controlled Multi-pulse HVDC ApplicationHVDC Application

167167


168168


169169

Controlled Multi-pulse Controlled Multi-pulse HVDC ApplicationHVDC Applicationinverter mode of inverter mode of

opeartionopeartion

170170

Controlled Multi-pulse HVDC ApplicationControlled Multi-pulse HVDC Application

ControlControl

171171


172172


173173

Controlled Controlled Multi-pulse Multi-pulse (36 pulse)(36 pulse)

174174

Controlled Multi-pulse (36 pulse) Controlled Multi-pulse (36 pulse) conventional methodconventional method

175175

Controlled Multi-pulse (36 pulse)Controlled Multi-pulse (36 pulse)modified methodmodified method

176176

Selection Criterion of Multipulse AC-DC Selection Criterion of Multipulse AC-DC ConvertersConverters

Number of phases in AC mains Number of phases in AC mains Required level of power quality in input (permitted PF, CF, Required level of power quality in input (permitted PF, CF,

THD)THD) Type of output DC voltage (constant, variable, etc.)Type of output DC voltage (constant, variable, etc.) Power-flow (unidirectional and bi-directional)Power-flow (unidirectional and bi-directional) Number of quadrants (one, two or four)Number of quadrants (one, two or four) Nature of DC output (isolated, non-isolated)Nature of DC output (isolated, non-isolated) Requirement of DC output (Controlled and Uncontrolled)Requirement of DC output (Controlled and Uncontrolled) Required level of power quality in DC output (voltage ripple, Required level of power quality in DC output (voltage ripple,

voltage regulation)voltage regulation) Type of DC loads (linear, nonlinear, etc.)Type of DC loads (linear, nonlinear, etc.)

177177

Selection Criterion of Multipulse AC-DC Selection Criterion of Multipulse AC-DC ConvertersConverters

CostCost SizeSize WeightWeight EfficiencyEfficiency Noise level (EMI, RFI, etc.)Noise level (EMI, RFI, etc.) Rating (W, kW, MW, etc.)Rating (W, kW, MW, etc.) ReliabilityReliability Number of DC outputsNumber of DC outputs Environment (ambient temperature, altitude, pollution Environment (ambient temperature, altitude, pollution

level, humidity, types of cooling, etc.)level, humidity, types of cooling, etc.)

178178

REFERENCES1. IEEE Standard Practices and Requirements for General Purpose Thyristor DC Drives, IEEE Std. 597, 1983. 2. IEEE Guide for Specification of High-Voltage Direct Current Systems

Part I-Steady State Performance, IEEE Std. 1030, 1987.3. IEEE recommended practice for efficiency determination of alternating- current adjustable-speed drives. Part I - load commutated inverter synchronous motor drives, IEEE Std. 995- 1987.4. IEC 61000-3-2, Power Quality Measurement Methods, 2000.

IEEE Guide for Application and Specification of Harmonic Filters, IEEE Standards 1573, 2003.

5.5. J. Schaeffer, Rectifier Circuits: Theory and Design. New York: Wiley-J. Schaeffer, Rectifier Circuits: Theory and Design. New York: Wiley-Interscience, 1965.Interscience, 1965.

6.6. R. Wells, “Solid State Power Rectifiers – An Applied Technology”, R. Wells, “Solid State Power Rectifiers – An Applied Technology”, Granada, 1982.Granada, 1982.

7.7. G. Seguier, “Power Electronic Converters: AC/DC Conversion”, New G. Seguier, “Power Electronic Converters: AC/DC Conversion”, New York: McGraw Hill, New York, 1986.York: McGraw Hill, New York, 1986.

8.8. R. W. Lye (Editor), Power Converter Hand Book-Theory, Design, R. W. Lye (Editor), Power Converter Hand Book-Theory, Design, Applications, Power Delivery Department, GE Canada, Ontario, March Applications, Power Delivery Department, GE Canada, Ontario, March 1990.1990.

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Power Quality Improvements Using Multipulse Converters

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