ac to dc convertersrhabash/elg4139acdc11.pdflinear rectifier consist of: • transformer: steps ac...
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![Page 1: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/1.jpg)
ELG4139: Rectifiers and Controlled Rectifiers AC to DC Converters
![Page 2: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/2.jpg)
Linear Rectifier Consist of:
• Transformer: steps ac voltage up or down.
• Rectifier Diodes: change ac to “bumpy” dc.
• Filter Network: includes capacitors and inductors, smooths out the bumps.
• Voltage Regulator: keeps the voltage constant.
• Protection: usually a zener diode circuit.
![Page 3: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/3.jpg)
Example: Computer Power Supply
![Page 4: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/4.jpg)
Example: Adjustable Motor Speed Drive
![Page 5: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/5.jpg)
Power Supply Specifics: Half Wave Rectifier
Source: ARRL
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Half-Wave Rectifier
High ripple factor.
Low rectification efficiency.
Low transformer utilization factor.
![Page 7: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/7.jpg)
Power Supply Specifics Full Wave Center-Tapped Rectifier
Source: ARRL
![Page 8: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/8.jpg)
Power Supply: Full Wave Bridge Rectifier
Source: ARRL
![Page 9: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/9.jpg)
Filtering Capacitors are used in power supply filter networks. The
capacitors smooth out the rippled AC to DC.
Source: ARRL
![Page 10: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/10.jpg)
Rectifier Performance Parameters
22dcrmsac VVV
acdc PP / Rectification Efficiency
dcrms VVFF /
11 2
2
222
FFV
V
V
VV
V
VRF
dc
rms
dc
dcrms
dc
ac
Form Factor
Ripple factor
𝑃𝑎𝑐 = 𝑉𝑟𝑚𝑠𝐼𝑟𝑚𝑠
![Page 11: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/11.jpg)
Example 1: A half-wave rectifier has a pure resistive load of R Determine (a) The efficiency, (b) Form factor (c) Ripple factor.
mm
mdc
VVtdtVV ))0cos(cos(
2)sin(
2
1
0 R
V
R
VI mdc
dc
2)sin(
2
1
0
2 mmrms
VtVV
R
VI m
rms2
%53.40
2*
2
*
*
*
R
VV
R
VV
IV
IV
P
P
mm
mm
rmsrms
dcdc
ac
dc
57.12
2
m
m
dc
rms
V
V
V
VFF
211.1157.11 22 FFV
VRF
dc
ac
.
![Page 12: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/12.jpg)
Three-Phase Diode Bridge Rectifier
![Page 13: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/13.jpg)
Waveforms and Conduction Times of Three-Phase Bridge Rectifier
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Three-Phase Full-Wave Rectifier
![Page 15: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/15.jpg)
Example 2: A single-phase diode bridge rectifier has a purely resistive load of R=15 ohms and, VS=300 sin 314 t and unity transformer ratio. Determine (a) The efficiency, (b) Form factor, (c) Ripple factor, (d) and, (d) Input power factor.
VV
tdtVV mmdc 956.190
2sin
1
0
AR
VI m
dc 7324.122
VV
tdtVV mmrms 132.212
2sin
12/1
0
2
%06.81rmsrms
dcdc
ac
dc
IV
IV
P
P
11.1dc
rms
V
VFF
482.011 2
2
222
FFV
V
V
VV
V
VRF
dc
rms
dc
dcrms
dc
ac
Input power factor = 1cosPowerReal
SS
SS
IV
IV
PowerApperant
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Alternative! Controlled Switching Mode
• By using linear regulator, the AC to DC converter is not efficient and of large size and weight!
• Using Switching-Mode
• High efficiency
• Small size and light weight
• For high power (density) applications.
• Use Power Electronics!
![Page 17: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/17.jpg)
Thyristors and Controlled Rectifiers
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Controlled Rectifier Circuit
𝑉𝑑𝑐 =1
2𝜋 𝑉𝑝𝑠𝑖𝑛𝜔𝑡𝑑𝜔𝑡 =
𝑉𝑝2𝜋
𝜋
𝛼
1 + 𝑐𝑜𝑠𝛼
𝑉𝑟𝑚𝑠 =1
2𝜋 𝜋
𝛼
𝑉𝑝2𝑠𝑖𝑛2𝜔𝑡𝑑𝜔𝑡
1/2
=𝑉𝑝
2
1
𝜋𝜋 − 𝛼 +
𝑠𝑖𝑛2𝛼
2
1/2
![Page 19: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/19.jpg)
Example: Consider the following SCR-based variable voltage supply. For RL=240 Ohm, derive the RMS value of the load voltage as a function of the firing angle, and then calculate the load power
when the firing angle is 0, /2, and .
![Page 20: AC to DC Convertersrhabash/ELG4139ACDC11.pdfLinear Rectifier Consist of: • Transformer: steps ac voltage up or down. • Rectifier Diodes: change ac to “bumpy” dc. • Filter](https://reader030.vdocuments.us/reader030/viewer/2022021609/5d3e1e1588c9939f158d8419/html5/thumbnails/20.jpg)
Full-Wave Rectifiers Using SCR
𝑉𝑑𝑐 =2
2𝜋 𝑉𝑝𝑠𝑖𝑛𝜔𝑡𝑑𝜔𝑡 =
2𝑉𝑝𝜋
𝜋+𝛼
𝛼
𝑐𝑜𝑠𝛼
𝑉𝑟𝑚𝑠 =2
2𝜋 𝜋+𝛼
𝛼
𝑉𝑝2𝑠𝑖𝑛2𝜔𝑡𝑑𝜔𝑡
1/2
=𝑉𝑝
2 = 𝑉𝑠
With a purely resistive load, SCRs S1 and S2 can conduct from to , and SCRs S3 and S4 can conduct from + to 2.