Faculty of Engineering & Applied Science (FEAS)
Department of Electrical and Electronic Engineering
Program: B.Sc. in EEE
Course Code: EEE 378 Name of Course: Power Electronics Laboratory
Experiment No. 04: THREE PHASE HALF & FULL-WAVE CONTROLLED
RECTIFIER
Objectives of this experiment are to:
1. Understand and learn how diode characteristics are used to rectify three phase AC voltage to DC
voltage.
2. Learn the advantages of full wave rectifiers over half-wave rectifiers.
3. Learn the advantages of controlled rectifiers over uncontrolled rectifiers.
4. Learn how gate signals are generated for controlled rectification.
Course Outcomes (COs), Program Outcomes (POs) and Assessment:
Domain / level
Expt Delivery methods
CO Statement Corresponding PO of learning Assessment tools
No. and activities
taxonomy
Lab tests
Simulation
CO1: Implement Investigation
Lab reports
different designed (PO4) Experiment
converters such as Modern Tool Affective Final lab test
01 domain/ Practice lab
AC-DC, DC-DC, Usage: (PO5)
analyzing level Open ended lab
AC-AC, DC-AC etc. Group
discussion Project show
& project
Tutorial
presentation
Lab tests
Simulation
CO2: Design
Lab reports
different converter Investigation Experiment
circuits using PSIM (PO4) Affective Final lab test
02 Modern Tool domain/analyzi Practice lab
software.
Usage: (PO5) ng level Open ended lab
Group
discussion Project show
& project
Tutorial
presentation
Required Equipments:
1. ED-2040-D (THREE PHASE HALF/FULL WAVE CONTROLLED RECTIFIER)
2. Signal Generator
3. Oscilloscope
4. Load connection cord
5. Power supply connection cord
Theory:
Figure 4-1: Three phase full wave controlled rectifier
Figure 4-1 shows three phase full-wave phase control rectifier and Figure 4-2 shows the output
waveform. That is, expressed each voltage and current waveform of when SCR's firing angle is acted
in α = 60, α = 90, α = 120.
π π π π
S6 is already shorted in wt = +α . if S1 is shorted, S6 and S1 is shorted in +α <wt < + α + . Phase
6 6 6 3
a and phase b are connected and that becomes line voltage i.e. Vab is output voltage. SCR s position is
connected with Figure 4-1, action order is shorted by S1S2, S2S3, S3S4, S4S5, S5S6, S6S1. SCR repeats
action of this process in every 60O.
The average output voltage Vab is given by:
π
+α
2
π
V ab=
3
∫ V ab dt = 3 √π2V cos α
π
+α
6
Figure 4-2: Output waveform of three phase full wave controlled rectifier
Ripple of output terminal voltage is 6 pulses per a period because pulse of load current is made by 6 SCR in
each gate signal. Here, SCR’s number is determined by action order by examining operation of three phase
converter.
Working Procedure:
1. Measurement of Sig-In Terminal Voltage: Connect the circuit as shown and record the
waveform.
Figure 4-1: Measurement of Sig-In terminal voltage of (a) Half wave rectifier. (b) Full wave
rectifier
2. Measurement of V-Ref terminal: Connect the circuit as shown and record the waveform.
Figure 4-2: Measurement of V-Ref terminal voltage of (a) Half wave rectifier. (b) Full wave
rectifier
3. Measurement of phase terminal: Connect the circuit as shown and record the waveform.
Figure 4-3: Measurement of phase terminal voltage of (a) Half wave rectifier. (b) Full wave
rectifier
4. Measurement of SCR gate voltage: Connect the circuit as shown and record the waveform
by adjusting the Volt-Variable knob and Phase-Variable knob.
Figure 4-4: Measurement of SCR gate voltage of (a) Half wave rectifier. (b) Full wave
rectifier
5. Measurement of input voltage: Connect the circuit as shown and record the waveform.
Figure 4-5: Measurement of input voltage of (a) Half wave rectifier. (b) Full wave rectifier
6. Measurement with R Load: Connect the circuit as shown and record the waveform by
adjusting the Volt-Variable knob and Phase-Variable knob.
Figure 4-6: (a) Half wave rectifier. (b) Full wave rectifier with R Load
7. Measurement with R-L Load: Connect the circuit as shown and record the waveform by
adjusting the Volt-Variable knob and Phase-Variable knob.
Figure 4-7: (a) Half wave rectifier. (b) Full wave rectifier with R-L load
8. Measurement with R-C Load: Connect the circuit as shown and record the waveform by adjusting
the Volt-Variable knob and Phase-Variable knob.
Figure 4-8: (a) Half wave rectifier. (b) Full wave rectifier with R-C load
Measured Results:
Observe, measure and record the waveform of the input voltage and the output voltage from steps 1-8
in working procedure. Plot them neatly in your graph paper.
Home Works:
1. Explain why the output wave shapes are different from each other in the steps above.
2. Comment on how the output wave shapes changed due to change in firing angle α.
3. Explain what benefits there would be with using controlled three phase rectifiers as compared
to uncontrolled three phase rectifiers.
