Week 8AC-to-AC Converters

Single-phase AC Voltage Controller

v

v

S O U R C E L O A D

T 1

T 2

i o

o

= i o i i i

2

3

Thyristor/Triac

SCR12N3668

MT12N6346

Single-Phase AC-AC Converter

Single-Phase AC-AC Converter

V1

240 V 60 Hz 0Deg

D12N5444

LOAD80kOhm

1 2

0

Single-Phase AC-AC Converter

Waveforms of Output Voltage and Current in a Single-phase AC Voltage

Controller (): (a) , (b)

7

Vi,p-

Vi,p

vi

42

vi

Vi,p

4

0 t

(b)

io

vo

e

f

(a)

-

Vi,p

0

f

e

io

vo

2 t

Envelope of Control Characteristics, ), of a Single-phase

AC Voltage Controller

8

FIRING ANGLE (deg)

0 30 60 90 120 150 180

MA

GN

ITU

DE

CO

NT

RO

L R

AT

IO

0.0

0.2

0.4

0.6

0.8

1.0

Operation of a Single-phase AC Voltage Controller with (a) Single-pulse Gate Signal, (b) Multi-pulse Gate Signal

9

ig2 ig1 ig2 io ig1

ig2 ig2 ig1 ig1

vi

42

vi

4

0 t

(b)

vo

f

(a)

0 f

io

vo

2 t

=

Definition of a Control Angle

10

vi

20 t

io

vo

e

f

'

Envelope of Control Characteristics, ), of a Single-phase AC Voltage

Controller

11CONTROL ANGLE (deg)

0 30 60 90 120 150 180

MA

GN

ITU

DE

CO

NT

RO

L R

AT

IO

0.0

0.2

0.4

0.6

0.8

1.0

Fully Controlled Three-phase AC Voltage Controller

12

av v vb c

T A T B T C

LO A D

A

B

C

Ai i iB C

S U P P L Y L IN E

Thyristor Gate Triggering

• Generation of the firing signal

• The sawtooth waveform (synchronized to the ac input) is compared with the control signal vcontrol, and the delay angle a with respect to the positive zero crossing of the ac line voltage is obtained in terms of vcontrol and the peak of the sawtooth waveform Vst.

st

controloo

V

v180

Full-Bridge (Single- and Three-Phase) Thyristor Converters

Voltage and Current Distribution in a Fully Controlled Three-phase

AC Voltage Controller: (a) Two Triacs Conducting, (b) Three

Triacs Conducting

15

v

v

v

B

A

v_1

(a) (b)

C

TBTA TC

vAB

Ai -iB

vAB BA

2 _ 21

TBTA TC

Ai i iB C

Av v vB C

v

v

v

B

A

C

Output Voltage Waveforms in a Fully Controlled Three-phase AC

Voltage Controller: (a) , (b) (R load)

16

vAC

vA=

vAB21

21

0

111

vB vCva

cba

f

t (deg)

(a)

t (deg)

(b)

va

0 30 60 90 120 150 180 210 240 270 300 330 360

-

-

f

0

0101

10

cba

vA

0 30 60 90 120 150 180 210 240 270 300 330 360

Polarities of Output Voltages and Currents in a Fully Controlled

Three-phase AC Voltage Controller in Mode 2 Before Firing Triac TA

(solid line) and Following the Firing (broken line)

17

(-)

0

(+)

(-)

0

(+)

FIRING ANGLE (deg)

0 60

PO

LAR

ITY

90

PHASE C

PHASE B

PHASE A

(-)

0

(+)

Output Voltage Waveforms in a Fully Controlled Three-phase AC voltage

Controller: (a) , mode 2, (b)

18

vACvAB

21

21

12

1

1

0 10

01

vAC

vABvA

0

va

cba

f

0

t (deg)

(a)

t (deg)

(b)

va

0 30 60 90 120 150 180 210 240 270 300 330 360

--

f

0

1

011

0

cba

vA

0 30 60 90 120 150 180 210 240 270 300 330 360

-2

-

Envelope of Control Characteristics) of a Fully Controlled Three-phase AC

Voltage Controller

19

FIRING ANGLE (deg)

0 30 60 90 120 150 180

MA

GN

ITU

DE

CO

NT

RO

L R

AT

IO

0.0

0.2

0.4

0.6

0.8

1.0

Envelope of Control Characteristics, ), of a Fully Controlled Three-phase

AC Voltage Controller

20

CONTROL ANGLE (deg)

0 30 60 90 120 150 180

MA

GN

ITU

DE

CO

NT

RO

L R

AT

IO

0.0

0.2

0.4

0.6

0.8

1.0

Three-phase AC Voltage Controllers Connected Before the Load: (a) Half-

controlled, (b) Delta-connected

21

A

B

C

A

B

C

(a )

(b )

Three-phase AC Voltage Controllers Connected After the Load: (a) Wye-

Connected, (b) Delta-connected

22

(a)

(b)

A

B

C

A

B

C

Three-phase Four-wire AC Voltage Controller

23

A

B

C

N

Single-phase AC Chopper with an Input Filter

24

i i i i'

vov i

i o

S 1

S 2

S 3 S 4

Waveforms of Voltages and Currents in a Single-phase AC chopper: (a) Output Voltage and Current, (b) Input Voltage and Current After the Input Filter, and the Fundamental

Output Current

25

ii,1ii

io

vo

vi

t0

(a)

1

t0

(b)

Control Characteristic of an AC Chopper

26

MODULATION INDEX

0.0 0.2 0.4 0.6 0.8 1.0

MA

GN

ITU

DE

CO

NT

RO

L R

AT

IO

0.0

0.2

0.4

0.6

0.8

1.0

Wye-connected Three-phase AC Choppers: (a) Three-wire,

(b) Four Wire

27

(b )

S 2 S 1

S 4S 3

S 2 S 1

S 4S 3

(a)

A

B

C

A

B

C

N

Delta-connected Three-phase AC Chopper

28

S1 S4

S2 S3

Changes in the Firing Angle in a Cycloconverter

29

M=0.5

(deg

)

0 60 120 180 240 300 360

0

30

60

90

120

150

180

M=0

M=0.25

M=0.75

M=1

(deg)ot

f

Output Voltage Waveforms in a Six-pulse Cycloconverter: (a) M = 1, (b) M = 0.5 (

30

vo1

vo1

ot

ot0

(a)

0

(b)

Three-phase Three-pulse Cycloconverter

31

Three-phase Six-pulse Cycloconverter with Isolated

Phase Loads

32

Three-phase Six-pulse Cycloconverter with

Interconnected Phase Loads

33

Three-phase to Three-phase (3-3) Matrix Converter

34

SUPPLY LINE

INPUT FILTER

LOAD

A B C

a

b

cS A b

S A c S C c

S A a

S B b

S B a

S B c

S C a

S C b

iA i iB C

vA v vB C

i i ia b c

v v va b c

vn

MATRIXCONVERTER

Arrangement of 3-1 and 1-3 Matrix Converters, Equivalent to a

3-3 Matrix Converter

35

A B C

a b c

S S

S S

S

SP a P b P c

N a N b N c

P

N

I

V

C O N V 1 C O N V 2

dc

dc

S AP S B P S C P

S AN S B N S C N

State AAB as Realized by Activation of Switches in (a) Virtual Rectifier and Inverter, (b) Matrix Converter

36

S S

S S

S

S

A B C

S S

S S

S

S

ba c

AP BP CP

AN BN CN

Pa Pb Pc

Na Nb Nc

S S

S S

S

S

A B C

S SS

a

b

c

Aa Ba Ca

Ab Bb Cb

Ac Bc Cc

(a)

(b)

P

N

37

TABLE 5.1 Switching Pattern for 3Φ-3Φ Matrix Converter with Space Vector PWM

Switching Subcycle Rectifier State Inverter State 𝒕𝒏 𝑻𝒔𝒘Τ 1 XI XV dXIdXV/2 2 XI YV dXIdYV/2 3 YI YV dYIdYV/2 4 YI XV dYIdXV/2 5 ZI ZV 1 – (dXI + dYI )( dXV + dYV) 6 YI XV dYIdXV/2 7 YI YV dYIdYV/2 8 XI YV dXIdYV/2 9 XI XV dXIdXV/2

Output Voltage and Current Waveforms in a 3-3 Matrix Converter: (a) N = 48, m = 0.7, (b) N = 12, m = 0.35,

38

0

(a)

(b)

i

vo

vo

io

o

o

o

t

t

Reference Current Vector in the Vector Space of input Currents of the Virtual

Rectifier

39

d

jq

i*

I

I

I

I

I

I II II

IV

V V I

I*

2_3 I

0PN

PN0IN0P

0NP

INP0

Ij 3 DC

DC

P0N

Reference Voltage Vector in the Vector Space of Line-to-Neutral Output Voltages of the Virtual Inverter

40

V

V

jq

d

VI

I

IV

II

V

III V *v *

V

V

V

DC

__V 3

2j VDC PPN

PNN

PNPNNP

VNPP

VNPN

Bidirectional Semiconductor Power Switches: (a) Two IGBTs and Two

Diodes, (b) One IGBT and Four Diodes

41

(a ) (b )

42

TABLE 5.2 Switching Pattern for the Example Matrix Converter

Switching Subcycle Rectifier State Inverter State 𝒕𝒏 𝑻𝒔𝒘Τ 1 0PN PPN 0.156 2 0PN NPN 0.035 3 NP0 NPN 0.009 4 NP0 PPN 0.057 5 Z00 or 0Z0 PPP 0.486 6 NP0 PPN 0.057 7 NP0 NPN 0.009 8 0PN NPN 0.035 9 0PN PPN 0.156

TABLE 5.3 Activation of Switches in the Example Matrix Converter

Switching Subcycle State of Matrix Converter Activated Switches Duration (µs) 1 BBC SBa, SBb, SCc 31.2 2 CBC SCa, SBb, SCc 7.0 3 ABA SAa, SBb, SAc 1.8 4 BBA SBa, SBb, SAc 11.4 5 BBB SBa, SBb, SBc 97.2 6 BBA SBa, SBb, SAc 11.4 7 ABA SAa, SBb, SAc 1.8 8 CBC SCa, SBb, SCc 7.0 9 BBC SBa, SBb, SCc 31.2

Switching Signals for Individual Switches in a Matrix Converter

43

TIME, s

0 50 100 150 200

S

Aa

Ab

Ac

Ba

Bb

Bc

Ca

Cb

Cc

S

S

S

S

S

S

S

S

45

Switching Characteristics

46