introduction to power electronics by d. w. hart chapter 8....
TRANSCRIPT
![Page 1: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/1.jpg)
Electrical Engineering
Power Electronics
1
Introduction to Power Electronics
by D. W. Hart
Chapter 8. Inverters (1)
: Converting AC to DC
![Page 2: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/2.jpg)
Electrical Engineering
Power Electronics
2
1 Full Bridge Converters (전브리지 변환기)
Contents
2 Square Wave Inverters (구형파 인버터)
3 Fourier Series Analysis
(퓨리에 급수해석)
4 Total Harmonic Distortion
(총고조파 왜율)
5 기본파의 크기 및 고조파 제어
![Page 3: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/3.jpg)
Electrical Engineering
Power Electronics
3
What is Inverter?
? No!
DC AC?
Arrow direction means the power flow under the normal
(powering) operation.
Converter? AC to DC. Invert this? DC to AC. So Inverter!
![Page 4: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/4.jpg)
Electrical Engineering
Power Electronics 4
AC to AC. How? Combine Converter (AC to DC) and
Inverter (DC to AC). cf. cyclo-converter, matrix converter.
AC → Rectifier + Capacitor → DC → Chopping → AC
Supply Voltage from Generator
220V/60Hz (Fixed)
Supply Voltage to Load
118V/19Hz (Variable)
Diode IGBT, Diode
or MOSFET
Why need Inverter?
![Page 5: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/5.jpg)
Electrical Engineering
Power Electronics 5
Vdc Switch1
Switch2
+_
Ideal switching waveform! Zero switching
loss!
Current Voltage
But the opposite switch must have
the below switching waveform.
Current
Voltage
Loss Power
Unless di/dt and dv/dt are
all infinite, switching loss
is inevitable.
The higher di/dt and dv/dt,
the bigger noise.
Switching Loss vs. EMI
![Page 6: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/6.jpg)
Electrical Engineering
Power Electronics
6
Full Bridge Converters
(전브리지 변환기) 스위치의 단락 출력전압
S1 과S2
S3 과S4
S1 과S3
S2 과S4
+Vdc
-Vdc
0
0
S1과S4, S2와S3가 동시에 닫히면 단락회로를 구성하므로 이러한 스위칭 상태는 피해야 한다. 실제 스위치의 제어에서는 스위치가 소호되는데 시간이 필요하므로 스위치의 전환시 강제적인 공백시간(Dead time)이 필요하다.
![Page 7: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/7.jpg)
Electrical Engineering
Power Electronics
7
Square Wave Inverters 1
(구형파 인버터) 부하가 직렬 R-L부하이고 출력전압이 구형파 일때 t=0에서 스위치 S1과 S2가 닫혀있을 때 출력전압은 Vdc이고, 전류는 다음처럼 나타내진다.
/
0
min
min
( ) ( ) ( )
, 02
τ: L/R
0, (0)
O f n
tdc
dc
O
dc
i t i t i t
V TAe t
R
VAt t i Ae I
R
VA I
R
![Page 8: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/8.jpg)
Electrical Engineering
Power Electronics
8
Square Wave Inverters 2
(구형파 인버터) t=T/2에서 스위치 S1과 S2가 열리고, S3과 S4가 닫혀있을 때, 출력전압은 –Vdc가 되고 이때의 전류는 다음처럼 나타내진다.
( / 2) /
0
max
max
( ) ( ) ( )
,2
, (0)2
O f n
t Tdc
dc
O
dc
i t i t i t
V TBe t T
R
VTAt t i Be I
R
VB I
R
![Page 9: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/9.jpg)
Electrical Engineering
Power Electronics
9
Square Wave Inverters 3
(구형파 인버터) /
min
( / 2) /
max
max
( / 2 )
max min
/ 2
max min / 2
2
m0
02
(0)
2
,2
( )2
1
1
1 2( )
tdc dc
O
t Tdc dc
O
Tdc dc
T
dc
T
Tdc
rms O
V V TI e t
R Ri
V V TI e t T
R R
TAt t i I
V VTi I I e
R R
V eI I
R e
VI i t dt I
T T R
2
/ 2/
in0
TtdcV
e dtR
![Page 10: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/10.jpg)
Electrical Engineering
Power Electronics
10
Square Wave Inverters 4
(구형파 인버터)
스위치에는 양의 전류와 음의 전류 모두 흐를수 있어야 한다. 각 스위치에서 역방향의 전류는 병렬 궤환 다이오드를 통해 흐른다. 부하전류는 연속이어야 하므로 다이오드를 통해 흐르는 전류가 0이 되기 전에 스위치쌍은 도통되어야 한다.
![Page 11: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/11.jpg)
Electrical Engineering
Power Electronics
11
Fourier Series Analysis
(퓨리에 급수해석)
1 1
2
1
2
, ,
1 1
0
,
( ) sin( ), ( ) sin( )
,2
:
, / 2
.
4( ) sin( )
O n O n O n O n
n n
n n
rms n
n n
n
n n rms n rms n
n n
dc
O
n odd
v t V n t i t I n t
I VI I
Z
Z n
P P I R I I
Vv t n t
n
차고조파에서의부하임피던스
부하저항에서소모되는전력
구형파의퓨리에급수는다음과같다
![Page 12: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/12.jpg)
Electrical Engineering
Power Electronics
12
THD
(총고조파 왜율)
2
2 2,1,2
1, 1,
11,
2
2
2 2
1,
1,
2
2
,
2
1,
4,
2 2
4
248.3%
4
2
8 1
1.42 0
2
n rmsrms rmsn
rms rms
dc
rms dc rms
dcdc
rms rms
v
dcrms
n rms
n
i
rms
VV V
THDV V
VVV V V
VV
V VTHD
VV
I
THDI
ex)구형파인버터에서전압및전류의THD
표 로부터
2 2 2
.53 0.27 0.17
2 2 216.7%
9.27
2
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Electrical Engineering
Power Electronics
13
기본파의 크기 및 고조파 제어 1
2
,
1 2( ) 1
( ) sin( )
42sin( ) ( ) cos( )
rms dc dc
O n O
n odd
dc
n dc O O
V V d t V
v t V n t
VV V n t d t n
n
스위치의 단락 출력전압
S1 과S2
S3 과S4
S1 과S3
S2 과S4
+Vdc
-Vdc
0
0
![Page 14: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/14.jpg)
Electrical Engineering
Power Electronics
14
기본파의 크기 및 고조파 제어 2
따라서 출력전압의 크기와 고조파 모두 alpha를 조정함으로써 제어할 수 있다. 다음 수식을 만족 하는 n차 고조파는 제거된다.
4cos( )dc
n
VV n
n
90
n
특정 고조파를 제어하기 위해 alpha를 결정하면 기본파의 크기를 제어할 수 없는 단점이 있다. 따라서 이 스위칭 방식에서 기본파의 크기와 고조파를 모두 제어하려면 직류입력전압의 크기 를 제어해야 한다.
![Page 15: Introduction to Power Electronics by D. W. Hart Chapter 8. …contents.kocw.net/KOCW/document/2015/gachon/shonjingeun/... · 2016-09-09 · AC to AC. How? Combine Converter (AC to](https://reader033.vdocuments.net/reader033/viewer/2022053001/5f0554c27e708231d4126f98/html5/thumbnails/15.jpg)
Electrical Engineering
Power Electronics
15
기본파의 크기 및 고조파 제어 2
따라서 출력전압의 크기와 고조파 모두 alpha를 조정함으로써 제어할 수 있다. 다음 수식을 만족 하는 n차 고조파는 제거된다.
4cos( )dc
n
VV n
n
90
n
특정 고조파를 제어하기 위해 alpha를 결정하면 기본파의 크기를 제어할 수 없는 단점이 있다. 따라서 이 스위칭 방식에서 기본파의 크기와 고조파를 모두 제어하려면 직류입력전압의 크기 를 제어해야 한다.