8/3/2019 Lecture 6 Diode Rectifier
1/36
RECTIFIER
Tuesday, May 01, 2012Dr. RS
1
8/3/2019 Lecture 6 Diode Rectifier
2/36
Half-Wave rectifier
8/3/2019 Lecture 6 Diode Rectifier
3/36
Block diagram of a rectifier and a dc power supply with a load.
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
8/3/2019 Lecture 6 Diode Rectifier
4/36
Half-wave rectifier operation. The diode is considered to be ideal.
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
8/3/2019 Lecture 6 Diode Rectifier
5/36
The effect of the barrier potential on the half-wave
rectified output voltage is to reduce the peak value ofthe input by about 0.7 V.
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
Copyright 2005 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
8/3/2019 Lecture 6 Diode Rectifier
6/36
Vp
0
-VP
2
Vi(t)
t
VD
Vp - VD
0 2
Vo(t)
t
8/3/2019 Lecture 6 Diode Rectifier
7/36
Figure 23 Average value of the half-wave rectified signal.
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
Copyright 2005 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
8/3/2019 Lecture 6 Diode Rectifier
8/36
Average value of HWR
V
cos2
V
d0dsinV2
1
dtVT
1V
P
0
P
2
0 p
T
0DC
8/3/2019 Lecture 6 Diode Rectifier
9/36
RMS Value of HWR
4
V
sin4
V
d2cos12
1
2
Vd
2
V
d0dsinV2
1
dtVT
1V
P
0
P
P
0
P
2
0
2
p
T
0
2
rms
2
2
0
2
2
2
2
2
22
1
sin
8/3/2019 Lecture 6 Diode Rectifier
10/36
VDC
Vrms
t0
t1
t2
t3
Vp
VO
t
8/3/2019 Lecture 6 Diode Rectifier
11/36
The PIVoccurs at the peak of each half-cycle of the input voltagewhen the diode is reverse-biased. In this circuit, the PIV occurs
at the peak of each negative half-cycle.
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
Copyright 2005 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
8/3/2019 Lecture 6 Diode Rectifier
12/36
Half-wave rectifier with transformer-coupled input voltage.
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
Copyright 2005 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
8/3/2019 Lecture 6 Diode Rectifier
13/36
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
Copyright 2005 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
8/3/2019 Lecture 6 Diode Rectifier
14/36
Center-tapped Full-wave Rectifier
8/3/2019 Lecture 6 Diode Rectifier
15/36
Figure 211 Full-wave rectification.
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
Copyright 2005 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
8/3/2019 Lecture 6 Diode Rectifier
16/36
Average Value
V2
cos
V
dsinV
1
dtVT
1V
P
0
P
0p
T
0DC
8/3/2019 Lecture 6 Diode Rectifier
17/36
RMS Value
2
V
sin2
V
d2cos12
1
V
dsinV
1
dtVT
1V
P
0
P
P
0
2
p
T
0
2
rms
2
2
0
2
2
2
221
8/3/2019 Lecture 6 Diode Rectifier
18/36
Figure 213 A center-tapped full-wave rectifier.
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
Copyright 2005 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
B i ti f t t d f ll tifi N t th t th t th h th
8/3/2019 Lecture 6 Diode Rectifier
19/36
Basic operation of a center-tapped full-wave rectifier. Note that the current through theload resistor is in the same direction during theentire input cycle, so the output voltage
always has the same polarity.
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
Copyright 2005 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
8/3/2019 Lecture 6 Diode Rectifier
20/36
Center-tapped full-wave rectifier with a transformer turns ratio of 1.Vp(pri) is the peak value of the primary voltage.
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
Copyright 2005 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
8/3/2019 Lecture 6 Diode Rectifier
21/36
Center-tapped full-wave rectifier with a transformer turns ratio of 2.
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
Copyright 2005 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
8/3/2019 Lecture 6 Diode Rectifier
22/36
Diode reverse voltage (D2 shown reverse-biased and D1 shown forward-biased).
Thomas L. Floyd
Electronic Devices, Electron Flow Version, 5e
Copyright 2005 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
8/3/2019 Lecture 6 Diode Rectifier
23/36
Full-Wave Bridge Rectifier
http://lecture%205%20bridge%20rectifier.ppt/http://lecture%205%20bridge%20rectifier.ppt/http://lecture%205%20bridge%20rectifier.ppt/http://lecture%205%20bridge%20rectifier.ppt/8/3/2019 Lecture 6 Diode Rectifier
24/36
Figure 223
24
Dr. RS Tuesday, May 01, 2012
8/3/2019 Lecture 6 Diode Rectifier
25/36
Figure 220 Operation of a bridge rectifier.
25
Dr. RS Tuesday, May 01, 2012
8/3/2019 Lecture 6 Diode Rectifier
26/36
Figure 221 Bridge operation during a positive half-cycle of the primary and secondary voltages.
26
Dr. RS Tuesday, May 01, 2012
8/3/2019 Lecture 6 Diode Rectifier
27/36
Vp
0
-VP
2
Vi(t)
t
Vp - VD
0 2
Vo(t)
t
27Dr. RS Tuesday, May 01, 2012
i k l d d d b d f
8/3/2019 Lecture 6 Diode Rectifier
28/36
Figure 222 Peak inverse voltages across diodes D3 andD4 in a bridge rectifierduring the positive half-cycle of the secondary voltage.
28
Dr. RS Tuesday, May 01, 2012
8/3/2019 Lecture 6 Diode Rectifier
29/36
Figure 224 Power supply filtering.
29
Dr. RS Tuesday, May 01, 2012
8/3/2019 Lecture 6 Diode Rectifier
30/36
Figure 230
30
Dr. RS Tuesday, May 01, 2012
8/3/2019 Lecture 6 Diode Rectifier
31/36
Figure 225 Operation of a half-wave rectifier with a capacitor-input filter. The current indicates charging or discharging of the capacitor.
31
Dr. RS Tuesday, May 01, 2012
8/3/2019 Lecture 6 Diode Rectifier
32/36
Figure 226 Half-wave ripple voltage (green line).
32
Dr. RS Tuesday, May 01, 2012
8/3/2019 Lecture 6 Diode Rectifier
33/36
Figure 227 The frequency of a full-wave rectified voltage is twice that of a half-wave rectified voltage.
33
Dr. RS Tuesday, May 01, 2012
8/3/2019 Lecture 6 Diode Rectifier
34/36
Figure 228 Comparison of ripple voltages for half-wave and full-wave rectified voltages with the same filter capacitor and load and derived from thesame sinusoidal input voltage.
34
Dr. RS Tuesday, May 01, 2012
8/3/2019 Lecture 6 Diode Rectifier
35/36
Vr
and VDC determine the ripple factor.
Vp(rect) : unfiltered peak rectified voltage
Vr(pp) : peak to peak ripple voltage
VDC : average value of ripple voltage
rhwr Vr(pp )
VDC
1
2 3fRLC
35
Dr. RS Tuesday, May 01, 2012
rfwr Vr(pp )
VDC
1
4 3fRLC
8/3/2019 Lecture 6 Diode Rectifier
36/36
Effects of RL and C
Tuesday May 01 2012Dr RS
36
C=1000F C=470F
C=100F
R=1500
R=1000
R=500
(a) RLfixed (b) C fixed