Transcript Power Supplies - University at Buffalo

Input
Filter
Regulation
Load
Experiment # 7
EE 312 Basic Electronics
Instrumentation Laboratory
Wednesday, October 25, 2000
Objective:
• Design, construct, and test a dc
power supply. The power
supply includes a transformer,
diodes, and a filter. All were
investigated in previous
experiments. This the major
design project in the course.
DC-VOLTAGE POWER SUPPLY OPERATION
Alternator
Transformer
or
Power Company
Rectifier
Filter
Regulator Load
v
t
Input: 120
VAC RMS,
60 Hz
Steps the
input
voltage up
and down
as needed
Convert the
ac to a
pulsing dc
Low-pass
type for
removing
voltage
variation
Keeps
voltage
constant
regardless of
load change
Power Company Transformer
Rectifier
Filter
v
167
118 Vrms
16.7 ms or 60Hz
t
Regulator Load
Alternator
Transformer
or
Power Company
v
167
Rectifier
Filter
Regulator Load
v
118 Vrms
25.5
18 Vrms
16.7 ms or 60Hz
t
16.7 ms or 60Hz
t
Alternator
Transformer
or
Power Company
Rectifier
Filter
v
Regulator Load
60Hz
RLoad
t
half-wave rectifier
v
RLoad
120Hz
t
full-wave rectifier
Alternator
Transformer
or
Power Company
v
25.5
Rectifier
~ 0.6V
18 Vrms
Filter
v
24.9
Regulator Load
60 Hz
12.45 Vrms
16.7 ms or 60Hz
t
t
half-wave rectifier
t
Alternator
Transformer
or
Power Company
Input
Rectifier
Filter
Filter
Regulator Load
Regulation
Load
Input
Filter
Regulation
Load
C

v
v
e
t
RC
ripple
Vmax
t
without C
t
t
with C
t
?
Vmax
?
v
V ripple
VDC
0
t
t
t
Input
Vinput
Filter
R
Regulation
Load
C
One or more filter sections are usually used to reduce the amplitude
of the ripple. The filter used in this experiment is a single-section
low-pass RC filter.
Alternator
Transformer
or
Power Company
Rectifier
Filter
Regulator Load
We design and built a 12 V dc
regulated power supply.
In this experiment you use a Zener
diode that breaks down at 12 V.
IDC
ILoad
Iz
12Volts
breakdown
voltage
ID
Forward
Characteristics
VD
Reverse
Characteristics
Iz
~
I
Max
IDC
Rs
Voltage Divider
Rs
ILoad
IDC
ILoad
Vinput
RLoad
Rz
Iz
=
Rz
RLoad
Iz
ID
1
rz
VD
1
Rz
~
I
Max
Vz, DC
Rz

Vinput Rs  Rz
Vz, ripple
rz

Vinput , ripple Rs  rz
Summary
Alternator
Transformer
or
Power Company
v
t
Rectifier
Filter
Regulator Load
Procedures:
I- Design, construct, and test a
dc power supply. Week 1
II- Simulate dc power supply.
Week 2
Components:
•
•
•
•
•
•
•
18 Volts Transformer
Variac
Bridge rectifier (use 1 diode)
Zener diode (Vbd=12Vdc, 1N4742)
12 Watt, 1000 Ohm, variable resistor
2 Resistor Substitution Boxes
50, 100, and 200 F Fixed Capacitors
1- Design, construct, test a dc power supply
R?
R?
ILoad = ?
VLoad =12 V dc
C?
Peak to peak
ripple voltage
from the input
stage = ?
C?
R?
Peak to peak
ripple voltage at
the load = ?
Vmax = 24.9 v
Vripple
VDC=22.4 V
Vmin=19.92
0
t
t
20% ripple
t
2- Simulation of Part I
Simulate the dc power supply!
Show output wave form at points 1, 2, and 3.
Comnpare these waveforms with your experiment.
1
2
3
RF=100
?
118.4 V
Rs=100
VLoad =12 V dc
CI=250uF
CF=100uF
Iz=10.5mA
RL  511
Variac
variable
18.0 V
Transformer
Report is required
Electronic & Paper
Before 1 PM
Tuesday Nov. 21