2004.10.09
EE410L, Experiment #1
Brett Allan
Single-Phase Full-Wave Phase-Controlled Rectifier
I. Introduction
The objective of this experiment is to design, construct, and test a Single-Phase Full-Wave
Phase-Controlled Rectifier. The subsequent block diagram depicts the general circuit
configuration to be implemented.
The design analysis is broken into sections with each corresponding to a block or specific
component shown in Figure 1 below.
+
Full - Wave
N1
*R of Z
N2
R of L
Rectifier
Trigger
Circuit
SCR
Figure 1: Phase-Controlled Rectifier (Block Diagram)
*Note: RZ (i. e., “R of Z”) acts as a current limiter for the trigger circuit.
continued 
2004.10.09
EE410L, Experiment #1
Brett Allan
Single-Phase Full-Wave Phase-Controlled Rectifier
II. Design
Operational Concept
A typical implementation of a phase-controlled rectifier is to provide control over the average
voltage delivered to a load. The subsequent discussion describes how phase-control
accomplishes this proposition.
-
Assume that a fully rectified sine wave is provided:
-
The objective is to vary the average or D.C. voltage to a load.
We know
-
If we can vary α between 0° and 180° we can achieve substantial control over the
average voltage seen by our load.
α ≈ 45°
α ≈ 160°
After examining the foregoing graphs, it become evident that we can control the time (or phase)
at which our SCR is pulsed (and subsequently conducts) during each cycle. We are controlling
the D.C. voltage seen by the load. This is our primary objective.
continued 
2004.10.09
EE410L, Experiment #1
Brett Allan
Single-Phase Full-Wave Phase-Controlled Rectifier
II. Design (con’t)
Section #1 Design Specifications:
1) Average maximum load current (IL): 2.0 Amps
2) User adjustable range angle range: α = 30° to 160°
Section #2 Design Analysis:
Part 1: Assuring Specified Load Current (IL)
Discussion:
The objective herein is to calculate a value of RL (indicated in Figure #1) that will
ensure the average load current to be less than or equal to 2.0 Amps.
I of L -->
V of R
+
V of S
E avg
SCR
Figure 2: Load Current (Simplified Block Diagram)
VS = V M
avg
(
= 1/π ∫
=
[
]
=
=> Eavg = (
)
=
)] =
[ (
[ (
)]
)
Thus:
Eavg =
=>
(√
)
=
(√
)
Eavg = 108.037 Volts
continued 
2004.10.09
EE410L, Experiment #1
Brett Allan
Single-Phase Full-Wave Phase-Controlled Rectifier
II. Design (con’t)
Part 1 (cont.)
Now using the equivalent circuit with Eavg
By KVL
Eavg = ILRL + VSCR  RL =
=
VSCR ≈ 1.0 V
(
RL =
)
= 2.0 Amps
–
= 53.5 Ω
Let: RL ≥ 54 Ω
Power dissipation of RL (worst case)
Pavg =
(RL) = (2.0)2(54) = 216.0 Watts
Part 2: Trigger Circuit Design
Discussion: The objective of this section is to design a trigger circuit such that a trigger pulse will
be generated to activate the SCR @ phase angles between 30° and 160°. Additionally, this range
is to be user adjustable.
Applicable Circuit and Calculations
Figure 3: Trigger Circuit
continued 
2004.10.09
EE410L, Experiment #1
Brett Allan
Single-Phase Full-Wave Phase-Controlled Rectifier
II. Design (con’t)
Part 2 (cont.)
-
We know:
( )
⁄
(
)
Choose
(
-
)
Hence, we see that after one time constant (τ = RC) the voltage @ node A is 0.632 VZ.
The potential @ node B constitutes a reference voltage for the P.U.T. (i. e., when the voltage @
node A is infinitesimally greater than the reference voltage @ node B, the P.U.T. conducts).
Subsequently, for convenience, we will establish a reference voltage @ node B equal to 0.632
VZ.
Thus:
VB = 0.632 VZ  VB = 0.632 * (15V)
(
By V.D. :
)
VB = 9.48 Volts
Solving for R2:
(
VB = 9.48 V
Let
)
(

) (
)
= 1.164 kΩ
Choose R1 = 2.0 kΩ
R1 = 2.0 kΩ
&
R2 = 1.2 kΩ
Solving for ID (Assuming P.U.T. gate current is negligible)
)
= 4.69 mA
Power Dissipated by Voltage Divider (worst case R1)
(
)
75.2 Watts
continued 
2004.10.09
EE410L, Experiment #1
Brett Allan
Single-Phase Full-Wave Phase-Controlled Rectifier
II. Design (con’t)
Part 2 (cont.)
Timing Analysis for R-C Charging Branch
Input signal
f = 60 Hz
-
Rectified Signal
f = 120 Hz
Solving for the number of milliseconds per degree of phase shift
(
)(
)(
)
Now solve for the time required to shift 30° and 160°in phase.
T|α = 30° = 0.463 msec/degree (30°) = 1.388 msec
T|α = 160° = 0.463 msec/degree (160°) = 7.404 msec
1.388 msec ≤ τ ≤ 7.404 msec
-
The foregoing range of τ will ensure a phase shift range from 30° to 160° as long as the
reference voltage is approximately 0.632VZ
Solving for Radj and C:
Τ = RadjC
Radj|α = 30° =
Choose C = 0.2 µF
=
(
(
)
(
)
= 6,940 Ω
τ=
Radj|α = 160° =
=
(
(
(
)
)
= 37,020 Ω
τ=
(Note: A 50 kΩ “pot” will be implemented)
continued 
2004.10.09
EE410L, Experiment #1
Brett Allan
Single-Phase Full-Wave Phase-Controlled Rectifier
II. Design (con’t)
Part 3: Trigger Circuit Current Limiter (RZ)
Discussion: In this section the worst case current requirements calculated in the previous
sections will be used to determine the minimum current required to drive the trigger circuit.
Subsequently, RZ and its power dissipation are determined.
Applicable Circuit and Calculations
IZ required to drive trigger circuit (worst case)
IZ = IZENER + IR + ID = (25 + 2.31 + 4.69) mA = 32 mA
(IZENER ≈ 25 mA to ensure Zener operates in
avalanche mode.)
Figure 4: Trigger Circuit Current Limiter
Let IZ = 40 mA
=
2,350.0 Ω Choose RZ = 2.2 kΩ
Power Dissipation through RZ
(
)
3.93 Watts
III. Experimental Circuit (Complete Schematic)
Discussion:
The subsequent circuit depicts the actual circuit (with measured component values to be
employed as a single-phase full-wave phase-controlled rectifier.
continued 
2004.10.09
EE410L, Experiment #1
Brett Allan
Single-Phase Full-Wave Phase-Controlled Rectifier
III. Experimental Circuit (con’t)
Circuit (w/ component values):
Figure 5: Complete Single-Phase Full-Wave Phase Controlled Rectifier Schematic
IV. Bill of Materials
Component Types, Values, & Part Numbers
Component
Rectifier
RZ
VZ
Radj
C
R1
R2
RG
SCR
RL
P.U.T.
Value
--2.52 kΩ
--0  50 kΩ
0.2∙10-6 F
2.09 kΩ
1.20 kΩ
50 Ω
--75 Ω
---
Rating Specs
200VPRV @ 2.0 A
5.0 Watts
15V / 5 Watts
1 Watt
--0.5 Watts
0.5 Watts
0.5 Watts
200V/4 Amps(RMS)
High Power Decade
40 V / I ± 20 mA
Part No.
NTE 167
--NTE 5130 A
----------NTE 5455
EE 5412
NTE 6402
continued 
2004.10.09
EE410L, Experiment #1
Brett Allan
Single-Phase Full-Wave Phase-Controlled Rectifier
V. Experimental Results
-
Discussion: The circuit indicated in Figure #5 was established and tested as a phase-controlled
rectifier.
Initially, the rectifier and Zener diode were tested to insure proper operation prior to connecting
the reminder of the circuit.
The Zener diode was observed to clamp input signals @ 15 Volts while RZ acted as a current
limier for the Zener diode.
The rectifier was observed to generate a fully rectified sine wave at its output terminals.
Subsequently, the load and remaining trigger circuit were connected (as shown in Figure #5) and
the power scope placed across RL.
Radj was adjusted between 5 kΩ and 40 kΩ and the phase angle was observed shifting between
20° and 170°.
Typical Phase Shift Waveform across RL:
-
Finally, α was varied between 30° and 160° while monitoring IL and VL. Corresponding data
tables, plots, and conclusions were generated.
Part 1 Table I
Half Divisions on the Scope
Test Data for SCR type Phase-Controlled Rectifier
Division
7.0
9.34
11.6
14.0
16.3
18.7
21.0
23.4
25.7
28.0
30.4
23.7
35.0
37.4
39.7
Phase Angle α°
(degree)
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
VL Volts
104.0
99.6
91.7
80.4
72.3
63.5
55.3
49.1
35.2
25.6
17.0
10.8
6.0
3.0
0.9
IL(A)(VL/RL)
1.73
1.66
1.52
1.34
1.21
1.06
0.92
0.74
0.59
0.43
0.28
0.18
0.10
0.05
0.02
continued 
2004.10.09
EE410L, Experiment #1
Brett Allan
Single-Phase Full-Wave Phase-Controlled Rectifier
V. Experimental Results (con’t)
Part 2 Table II
Test Data for Load Variation of SCR type Phase-Controlled Rectifier
α
(°)
30
RL
VL
IL
(Ω)
(V)
(A)
60 104.0 1.68
<60 104.0 1.70
<60 104.0 1.72
90
60
<60
<60
55.3 0.88
55.2 0.90
55.3 0.91
160
60
<60
<60
3.0 0.05
3.0 0.05
3.0 0.05
Plot of SCR type Phase-Controlled Rectifier (Load Voltage vs. Phase Angle α)
120
100
y = 0.0016x2 - 1.1261x + 141.52
R² = 0.9918
80
60
40
20
0
0
50
100
150
200
-20
continued 
2004.10.09
EE410L, Experiment #1
Brett Allan
Single-Phase Full-Wave Phase-Controlled Rectifier
V. Experimental Results (con’t)
Plot for Load Variation of SCR type Phase-Controlled Rectifier
Load Voltage VL (Volts)
120
100
80
60
40
20
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Load Current IL (Amps)
VI. Conclusion
The objective of this experiment was to design, build, and test a Full-Wave Phase-Controlled
Rectifier.
Initially, we generated a design to provide triggering pulses to the SCR for phase angles between 30°
and 160°. Additionally, we were careful to ensure sufficient current to drive the trigger circuit under
worst-case conditions. The worst case power dissipation was determined for each element and the
appropriate components were selected.
Subsequently, the network indicated in Figurer #5 was constructed and tested. The test results
were very favorable as the analogue phase-controlled rectifier performed flawlessly to beyond the
specifications. The phase angle was controllable between 20° and 170° and the load current never
exceeded 2 Amps. With regard to the experimental plots, the VL, VS and α characteristic results were
just as expected. Additionally, VL remained approximately constant as IL varied at various phase angles.