Pe lab

Department of Electrical Drives and Power Electronics

Laboratory works in
POWER ELECTRONICS

Valery Vodovozov and Zoja Raud
http://learnelectronics.narod.ru/

Tallinn
2010

Contents
Introduction ................................................................................................................. 4
Safety warnings and experimentation rules ............................................................ 4
Laboratory works guidance ......................................................................................... 6
Part I. Diode rectifiers.............................................................................................. 6
Laboratory targets ............................................................................................... 6
Preparing to the lesson ....................................................................................... 6
Experimentation .................................................................................................. 7
Report contents ................................................................................................... 7
Following discussion ........................................................................................... 8
Part II. Thyristor rectifiers ........................................................................................ 9
Laboratory targets ............................................................................................... 9
Preparing to the lesson ....................................................................................... 9
Experimentation ................................................................................................ 10
Report contents ................................................................................................. 11
Following discussion ......................................................................................... 11
Part III. Transistor dc/dc converters ...................................................................... 13
Laboratory targets ............................................................................................. 13
Preparing to the lesson ..................................................................................... 13
Experimentation ................................................................................................ 13
Report contents ................................................................................................. 15
Following discussion ......................................................................................... 15
Bibliography .............................................................................................................. 17
Annexes .................................................................................................................... 18
1. Stand “Diode rectifiers” ..................................................................................... 18
2. Stand “Line-commutated converters”................................................................ 23
3. Stand “Self-commutated converters” ................................................................ 25

3

Introduction

Introduction
This is a tutorial aid to implement laboratory works in power electronics. The
students are expected to have acquired knowledge of electronic components,
standard electrical wiring, and electrical schematic symbols. The manual
complies with the curriculum and the syllabus of the course AAV0020 Power
Electronics.

Safety warnings and experimentation rules
1. Remember always that the stand is dangerous equipment. Never apply
the mains power if it may cause a danger or an injury. In the case of an
accident, the sufferer must be released from the voltage, using the nearest
safety switch. Thereafter the rescue service must be called (numbers 112
and 0112) and the first aid provided.
2. The stands are realized as the switchboards with the power sources and
measuring devices. The power sources are supplied with 400 V voltages
from the three-phase network. Their switching makes live circuits
composed for the laboratory work.
3. Never switch on the mains without the instructor’s permission. In the case
of overheating, smelling, the sparkles or electric arc between contacts,
switch off the power source immediately. Additionally, the red safety push-
button is located on the front panel of the main laboratory switchboard. In
the case of an emergency, press this button to switch off all stands. After
avoiding an emergency, pull out the emergency push-button to restore the
supply.
4. To assemble the circuits, devices and boards are equipped with sockets
and wires. The cord set of special safety wires of different length and
colour belongs to the outfit of the stands.
5. When assembling the circuits, enable free access to the feeder board,
stand, emergency switches, and test devices, which are adjusted during
the experimentation. All equipment and appliances should be well visible
and their displacement or pulling down from the table should be avoided.
Connect no more than two conductors to one terminal or socket.
6. To avoid electric shock, never open the covers and do not touch with
cables and wires while the mains power is applied. To change the circuit,
switch off the mains power. Do not control the circuits by the device
disconnecting; instead, use the panel keys and feeder board buttons.
7. Before energizing the stand, make sure that all devices and measuring
instruments are suitable for operation throughout the voltage and current
ranges provided by this manual. Do not run the circuits over the rated
voltages and currents and do not allow their long-term overloading.
8. It is prohibited to lean and sit, to hang clothes, to place bags, cases etc. on
the stands, to leave and to enter the laboratory without the instructor’s
permission, to eat, drink and smoke in the laboratory, to touch the devices
not needed for the given work, and to implement the experiments alone.

4

Introduction

9. Submit the protocols and other results to the instructor at the end of the
laboratory work. After instructor’s permission, take off the circuits, switch
off and return the measuring devices and equipment onto their places, and
leave the workplace in order.
10. Every student should implement the mandatory part of the works and may
implement the optional part given in small print. He/she must prepare and
defend the personal report having the title sheet and required contents.
Compliance of the results with the theoretical aspects and standards is
examined and expediency of the used methods and devices are to be
evaluated in the conclusions. Special attention should be paid to the
differences of the experimental and theoretical results, experiment errors,
mistaken measurement readings, and their reasons.

5

Diode rectifiers

Laboratory works guidance
Part I. Diode rectifiers
Learning uncontrolled ac/dc converters using the TTÜ stand
“Diode rectifiers”

Laboratory targets
1. Acquainting with the rectified effect of the diode ac/dc converters by
implementation the following works:
DM1 – Single-phase half-wave diode rectifier M1
DM2 – Single-phase midpoint diode rectifier M2
DB2 – Single-phase bridge diode rectifier B2
DM3 – Three-phase midpoint diode rectifier M3
DB6 – Three-phase bridge diode rectifier B6
2. Study the power electronic circuits that feed resistive and inductive loads
using the listed above rectifiers.
3. Recognizing the smoothing effects of the inductive load and filters.

Preparing to the lesson
1. Learn about the stand “Diode rectifiers” from Annex 1 in this manual. Find
the supply input and outputs using the stand diagrams.
2. Develop the circuit diagram of the desired rectifier outlined by the dotted
lines in Fig. A1.3, a, b. The rectifier ought to feed the resistive and
inductive loads (Fig. A1.3, c) without filtering and with different filters (Fig.
A1.3, d). Provide the circuit link-up with:
• dc voltmeter PV1 to measure the load dc voltage Ud
• ac voltmeter PV2 to measure the load ac rms voltage Ua
• dc ammeter PA to measure the load dc current Id
• oscilloscope to view the load voltage waveforms Ud(t)
3. Calculate expected rectified voltage Ud(0), peak-to-peak ripple voltage
Ur(0), and ac rms voltage Ua in the idle mode of operation (Id = 0) and
permissible load current Id max as follows:
Us U (0) I
Ud (0 ) = , U r (0) = 2U d (0) ⋅ K r , Ua (0) = r , Id max = s max
kU 2 2 kI
where Us is the rms supply voltage, Is max − permissible supply current,
assuming the following voltage, ripple, and current factors:
Rectifier KU Kr KI
M1 2,22 1,57 1,57
M2 1,11 0,78 0,71
B2 1,11 0,78 1,00
M3 0,85 0,25 0,58
B6 0,42 0,06 0,82

6

Diode rectifiers

4. Build expected voltage Ud(t) and current Id(t) waveforms and an expected
load curve Ud(Id) for resistive load within the current swing between zero
and the maximum permissible value.

Experimentation
1. Select the measuring devices and set the measuring ranges 5 A, 200 V
and sockets ±5 A, ±250 V for wiring. Choose a load rheostat, an inductor,
and/or a capacitor in accordance with the permissible load current. Set the
maximum resistance of the rheostat.
2. Assemble the desired rectifier using the positive and negative switchboard
sockets as outputs. Connect the rectifier inputs to the required
transformer. Connect the rectifier outputs to the load rheostat via the
ammeter. Link up the circuit with the parallel-connected voltmeters and
oscilloscope.
3. Self-examine the assembled circuit and ask the instructor to check it.
Power on the assembled circuit and ensure it operates properly. If the fault
occurs in any instant, power off the circuit immediately, examine it and
eliminate errors.
4. Along with the smooth decreasing of the rheostat resistance, measure the
load current Id and voltages Ud, Ua, fill the measured values in the protocol,
and build the load diagrams Ud(Id) and Ua(Id).
5. Estimate the waveform Ud(t) at the load currents Id given by instructor.
Determine the peak-to-peak voltage ripple Ur by the oscilloscope and
calculate the actual ripple factor at the given load current.
6. Restore the maximum resistance of the rheostat and power off the stand.
7. Repeat the above given items 3 to 6 at the inductive load.
8. Add a filter between the rectifier and the resistive load and repeat the items 3 to 6.
9. Following the instructor’s permission, take off the circuits and introduce
proper order in the workplace.
10. Signed protocol.

Report contents
1. Circuit diagram of the studying circuits given by an instructor, with
specification of the supply and load components.
2. Calculation of the idle voltage, ripple factors, and permissible current.
3. Table of the observed data Id, Ud, Ua, and the measured values Ur and Kr.
4. Scaled diagrams of the experimental load curves Ud(Id), Ua(Id) for resistive
and inductive loads, with/without filters.
5. Scaled diagrams of the expected current waveform Id(t) and the
experimental trace Ud(t), obtained at given current Id for resistive and
inductive loads, with/without filters.
6. Conclusions regarding estimation, comparison and explanation of the
expected and obtained results.

7

Diode rectifiers

Following discussion
Basing on the experiments, confirm and explain the following phenomena and
propositions:
1. The load curves of a rectifier depend on the load type.
2. The load curves of a rectifier depend on the filter type.
3. The load voltage and current depend on the load inductance.
4. The shape of the load voltage and current depend on the filter parameters.
5. The rectified voltages on the resistive load differ from those on the
inductive load.
6. The rms voltages on the resistive load differ from those on the inductive
load.
7. Along with the load increasing, the rms voltage of the inductive load grows.
8. An engineer may find the diode, rheostat, capacitor and inductor ratings
from different sources.
9. The current consumed by a rectifier depends on the rectifier type and
diode ratings.
10. The peak inverse voltage of a diode depends on the rectifier type and
supply voltage.
11. The forward current of the diodes depends on the rectifier type and supply
voltage.
12. The actual ripple factor differs from that calculated before experimentation.
13. Application areas of a rectifier depend on the rectifier type.
14. Using the diode ratings available from its data sheet, a diode output curve
may be built.
15. An active resistance of any electric circuit may be found using the load
curves and taking into account the diode output curve.
16. An active resistance of an inductor may be found using the load curves.
17. The circuit inductance, capacitance, and total resistance define the time
constants of a circuit.
18. The load resistance and inductance define a mathematical model of a
circuit.
19. The load resistance and filter parameters define a mathematical model of
a circuit.
20. With a given load current and time constants calculated, the minimum
frequency may be found to provide the continuous current mode.
21. With a given load current, an active power, apparent power, and a power
factor of the circuit may be found.

8

Thyristor rectifiers

Part II. Thyristor rectifiers
Control ac/dc converters using the Lucas-Nülle stand
“Line-commutated converters”

Laboratory targets
1. Acquainting with the control principles of the thyristor converters by
SM1 – Single-phase half-wave controlled rectifier M1
SB2 – Single-phase bridge controlled rectifier B2
SB6 – Three-phase bridge controlled rectifier B6
2. Study the power electronic circuits that feed resistive and inductive loads
from the controlled rectifiers.
3. Recognizing the control characteristics of the converters with resistive and
inductive loads.

1. Learn about the stand “Line-commutated converters” from Annex 2 in this
manual. On the panel of the stand (Fig. A2, a), find the supply inputs and
outputs, the power converter unit, the load, and the control units.
2. Develop the circuit diagram of the desired power converter outlined by the
dotted lines in Fig. A2, b, c. The converter ought to feed the resistive R
and inductive RL loads (Fig. A2, d, e). Provide the circuit link-up with:
• multimeter PS to measure the supply voltage Us, current Is, and
power components − active P, reactive Q, and apparent S
• dc voltmeter PV to measure the load voltage Ud
• oscilloscope or computer to plot the waveforms of the load voltage
Ud(t) and current Id(t)
3. Recognise the desired supply voltage Us and calculate expected values
Ud(0), Pd(0), P(0), S(0), Is(0), and Q(0) of an uncontrolled rectifier, using
the formulae:
Us
Ud (0 ) = – rectified voltage
kU

U d (0 )
2
Pd (0 ) = – power consumed by the load R
R
2
Us
P (0 ) = – active power
K sR
Pd (0 )
S (0 ) = – apparent power
cos φ(0 )
S (0 )
Is (0 ) = – supply current
Us

9


Q (0 ) = S (0 ) ⋅ sin φ(0 ) – reactive power
assuming the following voltage, circuit, and power factors:
Converter KU Ks cos φ(0)
M1 2,22 2 0,29
M2 1,11 1 0,64
B2 1,11 1 0,90
M3 0,85 1 0,64
B6 0,42 1 0,95
4. Build expected voltage and current waveforms Ud(t), Id(t) at the given firing
angle α and an expected control curve Ud(α) for resistive load within the
firing angle swing between zero and the maximum permissible value.

Experimentation
1. Select the required overlay mask and place it above the Power converter
unit. Ensure that the Universal control unit and the Differential amplifiers
A and D are connected correctly.
2. Assemble the desired power converter, link it with the Isolating
transformer, the measuring devices, and the Load R = 270 Ω. Following
the instructor’s directions, connect one of the registration devices to the
Differential amplifiers panel:
• oscilloscope to provide manual examination, or
• computer to provide computer control using PHACON software
Select the required type of control by setting the knob of the Universal
control unit to one of the following modes:
• RS 232 to control the rectifier from the PHACON computer program
• Mode 1 Phase control for the manual control of the single-phase
rectifier with an oscilloscope
• Mode 3 Phase control for the manual control of the three-phase
rectifier with an oscilloscope
3. Following the self-examination and checking the assembled circuit by the
instructor, power on the stand.
4. Switch on the DC power supply and the Multimeter.
5. Switch on the Isolating transformer. If the fault occurs in any instant, power
off it immediately, examine the circuit and eliminate errors.
6. Run the Universal control unit and ensure the circuit operates properly
using the required type of control:
• to provide computer operation, run PHACON, select the required
Mode from the Settings menu and the displaying signals and
scales from the Chart menu, then click the Start button, and
adjust the firing angle
• to control manually, turn the Set-point potentiometer of the
Universal control unit and estimate visually the waveforms Ud(t)
and Id(t) by the oscilloscope

10


7. Measure the actual rms supply voltage Us.
8. Using the Multimeter, define the rms supply current Is and the power
components − active P, reactive Q, and apparent S.
9. Along with the smooth changing of the firing angle α, measure the
mentioned supply values and the rectified voltage Ud, fill them in the
protocol, and build the matched control and power characteristics Ud(α),
P(α), Q(α) and S(α).
10. Use the computer or an oscilloscope to estimate waveforms Ud(t) and Id(t)
at the given firing angles α, count their peak-to-peak values, and plot the
scaled voltage and current waveforms.
11. Stop the Universal control unit and switch off the Isolating transformer.
12. Repeat the above given items 5 to 11 for the inductive load 270 Ω + 0,3 H.
13. Switch off the DC power supply and the Multimeter. After instructor
permission, power off the stand, take off the circuits, and introduce proper
order in the workplace.

Report contents
2. Calculation of Ud(0), Pd(0), P(0), S(0), Is(0), and Q(0) values for an
uncontrolled rectifier.
3. Table of the observed data − α, Ud, Is, P, Q and S.
4. Scaled diagrams of the experimental control and power characteristics
Ud(α), P(α), Q(α), and S(α) for resistive and inductive loads.
5. Scaled diagrams of the matched voltage and current waveforms Ud(t), Id(t)
obtained at given firing angle α for resistive and inductive loads.
6. Conclusions regarding estimation, comparison and explanation of the
7. Signed protocol.

propositions:
1. Load inductance affects the current conducting interval.
2. Inductance of the load causes the negative voltage transients.
3. Multi-quadrant operation mode is processed upon the negative dc
voltages.
4. Average value of the rectified voltage depends on the circuit type and the
number of phases.
5. Load inductance and resistance define the time constants of a circuit.
6. Load resistance and inductance define the circuit transients.

11


7. Rectified voltage falls non-linearly along with the firing angle growing.
8. With an inductive load, rectified voltage drops as compared to the resistive
load.
9. With an inductive load, controllability of the thyristor rectifier may be
limited.
10. With an infinitely large load inductance, voltage response and control
characteristic change significantly.
11. Active power consumption changes along with the growing of the firing
angle.
12. Reactive power depends on the firing angle.
13. Load current may be interruptible or continuous depending of the circuit
parameters.
14. With an inductive load, rectified current has no longer a sinusoidal
waveform.
15. Consumed active power of the bridge circuit is higher than that of the half-
wave rectifier.
16. Inductive load causes excessive overvoltages.
17. Some methods protect thyristors against overvoltages with an inductive
load.
18. Power vector diagrams depend on the firing angle.
19. With an inductive load, a phase shift occurs between the supply voltage
and the fundamental of the supply current.
20. For the given firing angle, expected Ud(t) and Id(t) waveforms may be
plotted without an oscilloscope.
21. At some circumstances, a rectifier may be considered as a voltage source
converter.

12

Transistor dc/dc converters

Part III. Transistor dc/dc converters
Learning IGBT converters using the Lucas-Nülle stand
“Self-commutated converters”

Laboratory targets
1. Acquainting with control principles of the IGBT converters by
TM1 – Single-quadrant dc/dc converter M1
TB2 – Multi-quadrant dc/dc converter B2
2. Study power electronic circuits feeding resistive and inductive loads from
the IGBT converters.
3. Recognizing the control characteristics of the IGBT converters.

1. Learn about the stand “Self-commutated converters” from Annex 3 in this
manual. Using the panel diagram of the stand (Fig. A3, a), find the supply
inputs and outputs of the studying system.
2. Develop the circuit diagram of the desired power converter given in
Fig. A3, b, by the dotted lines and supplied from the isolating transformer
(Fig. A3, c) to feed the resistive and inductive loads (Fig. A3, d, e). Provide
the devices link-up with:
• Multimeter PS to measure the actual load voltage Ud, current Id and
power Pd
• dc voltmeter PV to measure the actual supply voltage Us
• oscilloscope or computer to plot the waveforms of the load voltage
Ud(t) and current Id(t)
3. Recognize the expected supply voltage Us accessible from the B6 rectifier
of the Isolating transformer panel. For the duty cycles q given by an
instructor, calculate expected average values:
• load voltage Ud = qUs for the single-quadrant operation, or Ud =
Us(2q − 1) for the multi-quadrant operation
U
• load current Id = d
R
• dc power Pd = UdId
U2
• ac power Ps = s q (1 − q )
R
• active power P = Pd + Ps
U
• peak-to-peak current ripple Ir = k s t on (1 − q ) at the switching
L
frequencies 112 and 1800 Hz and load inductances 0,3 and 1,2 H
(k = 0,5 for the single- and 1 for the multi-quadrant operation)
4. Build an expected control characteristic Ud(q) within the duty cycle swing
0…1 and voltage and current waveforms Ud(t), Id(t) at the given duty cycle
for resistive load, low and high frequencies 112 and 1800 Hz.

13


Experimentation
1. Select the required overlay mask, place it above the Power converter unit,
and assemble the desired power converter.
2. Ensure that the Universal control unit and the Differential amplifiers A and
D are connected correctly.
3. Assemble the isolating transformer, connect the power converter to the
rectifier of the Isolating transformer panel, and link it to the Load RΣ =
810 Ω. Connect the required measuring devices. Set the jumper R3 =
8,0 Ω of the Power converter unit and, in the case of B2 converter, set also
the jumper Release V1…V4.
4. Following the instructor’s directions, connect one of the registration
devices to Differential amplifiers:
• oscilloscope to provide manual examination, or
• computer to provide computer control using the PWM software
Select the required type of control by setting the knob of the Universal
control unit to one of the following modes:
• RS 232 to provide the control from the PWM computer program
• PWM control LF for the manual control at low frequency of 112 Hz
with an oscilloscope
• PWM control HF for the manual control at high frequency of 1800 Hz
with an oscilloscope
5. Following the self-examination and checking the assembled circuit by the
instructor, power on the stand.
6. Switch on the DC power supply and the Multimeter.
7. Switch on the Isolating transformer. If the fault occurs in any instant, power
off it immediately, examine the circuit and eliminate errors.
8. Run the Universal control unit and ensure the circuit operates properly
using the required type of control:
• to control by computer, run PWM program, select the required
frequency from the Settings/Settings menu, then click the
Start/Stop button, set the scales from the Chart/Properties menu,
and adjust the duty cycle
• to control manually, turn the set-point potentiometer of the
Universal control unit and estimate visually the waveforms Ud(t)
and Id(t) by the oscilloscope
9. Measure the actual supply dc voltage Us
10. Use the computer or an oscilloscope to estimate waveforms Ud(t) and Id(t)
at the given duty cycles and count their peak-to-peak values. Then, plot
the scaled on-screen voltage and current waveforms.

14


11. Smoothly changing duty cycles, measure the load voltage Ud, current Id
and power Pd, fill them in the protocol, and build the control and power
characteristics Ud(q), Id(q) and Pd(q).
12. Stop the Universal control unit and switch off the Isolating transformer of
the stand.
13. Repeat the above given items 5 to 12 at high modulation frequency of
1800 Hz.
16. Switch off the DC power supply and the Multimeter. After instructor’s
permission, power off the stand, take off the circuits, and introduce proper
order in the workplace.

Report contents
2. Calculation of Ud, Id, Pd, Ps and P values for the given duty cycle.
3. Tables of observed data q, Ud, Id, and Pd.
4. Scaled diagrams of experimental control and power characteristics Ud(q),
Id(q), and Pd(q) at low and high frequencies for resistive and inductive
loads.
5. Scaled diagrams of experimental voltage and current waveforms Ud(t), Id(t)
obtained at the given duty cycle at low and high frequencies for resistive
and inductive loads.
6. Conclusions regarding the estimation, comparison and explanation of the
7. Signed protocol.

propositions:
1. Control and power characteristics depend on the duty cycle.
2. Control and power characteristics depend on the load.
3. Control and power characteristics depend on the pulse frequency.
4. A specialist can distinguish audibly between the low and high switching
frequency of an IGBT converter.
5. Current builds up while an IGBT is switched on and decays when it is
switched off.
6. Load inductance and resistance define the time constants of a circuit.
7. Load resistance and inductance define the circuit transients.

15


8. With an inductive load, the current reaches its stationary maximum state in
time that depends on the given switching frequency and duty factor.
9. At the given switching frequency and duty factor, the current reaches its
stationary maximum state in time that depends on the load inductance.
10. Current responses differ between the circuits with high inductance and
with low one.
11. Current responses may be the same for both the high frequency supply
and the low one.
12. Current responses may be different for the high frequency supply and the
low one.
13. Switching frequency affects the peak-to-peak current ripple for the given
duty cycle and load inductance.
14. Duty cycle affects the peak-to-peak current ripple at the given switching
frequency and load inductance.
15. It is possible to change the peak-to-peak current ripple upon the different
values of duty cycle.
16. Load inductance affects the dc power, ac power, and active power
consumed by the circuit.
17. Duty cycle affects the dc power, ac power, and active power consumed by
the circuit.
18. Switching frequency affects the dc power, ac power, and active power
consumed by the circuit.
19. Freewheeling diodes are the required components of dc/dc converters.
20. Role of the freewheeling diode differs dependently of the load parameters.
21. Role of the freewheeling diode differs dependently of the frequency and
duty cycle.

16

Bibliography

Bibliography
1. Vodovozov, V. and Jansikene, R., Power Electronic Converters, Tallinn:
TUT, 2006, 120 p.
2. Vodovozov, V. ja Jansikene, R., Jõuelektroonika (Tõlge inglise keelde),
Tallinn: TTÜ, 2008, 120 lk.
3. Joller, J., Jõuelektroonika, Tallinn, TTÜ elektriajamite ja jõuelektroonika
instituut, 1996, 216 lk.
4. Vodovozov, V. and Jansikene, R., Electronic Engineering, Tallinn: TUT,
2006, 148 p.
5. Vodovozov, V. ja Jansikene, R., Elektroonika ja Jõupooljuhttehnika (Tõlge
inglise keelde), Tallinn: TTÜ, 2008, 140 lk.
6. Vodovozov, V. and Vinnikov, D., Electronic Systems of Motor Drive,
Tallinn: TUT, 2008, 248 p.
7. Vodovozov, V., Vinnikov, D. ja Jansikene, R., Elektriajamite elektroonsed
susteemid (Tõlge inglise keelde), Tallinn: TTÜ, 2008, 240 lk.

Annexes

Annexes
1. Stand “Diode rectifiers”
The stand is realized as a feeder switchboard (Fig. A1.1) with the front panel
which represents the circuit composition field (Fig. A1.2). It is supplied with
400 V from the three-phase network by the feeder cable via the plug X1. To
decrease the voltage, the three-phase star-connected transformer T1 and the
single-phase central tapping transformer T2 are used. The main technical
data of T1 are as follows:
• apparent power 250 VA
• primary voltage 400 V
• secondary phase-to-phase voltage 24 V
• secondary phase-to-neutral voltage 14 V
• primary current 0,6 A
• secondary current 10 A
• number of phases 3
• interconnection Y0/Y0
The main technical data of T2 are as follows:
• apparent power 120 VA
• primary voltage 230 V
• secondary phase-to-phase voltage 48 V
• secondary phase-to-midpoint voltage 24 V
• primary current 0,5 A
• secondary current 5A
• number of phases 1

The yellow light H1 illuminates since the feeder cable is powered. To make
live the circuit composed for the laboratory work, the main switch S1 is
intended with lighting the green signal H2.

The red safety push-button S2 is located on the front panel. In the case of an
emergency, press this button. This way, the magnetic switch K1 is switched
off resulting in the red emergency light H3 illuminating. After avoiding an
emergency, pull out the emergency push-button and restore the supply.

The primary circuits of the T1 and T2 transformers are protected against
short-circuit and overloading by the automatic circuit breaker F1 (4 A rating).
The secondary circuit of the T1 transformer is protected by the automatic
circuit breaker F2 (10 A rating) and the secondary circuit of the T2 transformer
– by F3 (5 A rating). The circuit breakers are placed inside the switchboard.
To protect the F1 circuit breaker from the great current pulses arising along
with the switching on the transformer, the NTC thermistor (posistor) R1 is
connected sequentially into the primary circuit of the T2 transformer.

To assemble the required diode rectifiers, the stand includes six power diodes
D1…D6 25F60 with the rated on-state current IF = 25 A and the maximal
reverse voltage UR = 600 V. The diode data sheets are accessible at

18

Annexes

http://www.irf.com/product-info/datasheets/data/25f.pdf. The diodes have
three connection sockets X11…X22 both on the cathode and on the anode
terminals whereto the conductors of the composed circuit are connected.
There are eight sockets X23, X24 to connect the conductors of the positive
polarity (four sockets are connected sequentially with each other) and eight
sockets X25 to connect the conductors of the negative polarity. The sockets of
the negative polarity and the ac sockets are black and the sockets of the
positive polarity are red.

The cord set of special safety wires of different length and colour belongs to
the outfit of the stand. The black wires connect the negative parts of the circuit
and ac networks whereas the red ones connect the positive parts. To connect
the network neutral, the blue wires are used. There are the wires of 0,5 m and
2 m length. For the parts of an experimental circuit, which are placed on the
front panel, the wires of 0,5 m length are recommended to avoid the tackling.
Connections between the switchboard and the devices on the table should be
provided by the longer wires.

19

Annexes

Fig. A1.1. Circuit diagram of stand “Diode rectifiers”

20

Annexes

Fig. A1.2. Front panel of stand “Diode rectifiers”

21

Annexes

400 V 14 V Rectifier
L1 PA

M1 PV1 PV2
B2 Filter Load
L2

L3 B6
M3

a. Experimental circuit to study M1, B2, M3, and B6 rectifiers

L3

PA
24 V
Rectifier
230 V PV1 PV2
Filter Load
24 V M2

N

b. Experimental circuit to study M2 rectifier

c. Resistive and d. C and LC filters
inductive loads

Fig. A1.3. Experimental circuits of stand “Diode rectifiers”

22

Annexes

2. Stand “Line-commutated converters”

The stand is educational equipment produced by Lukas Nülle Company to
study controlled line-commutated converters built on thyristors and diodes.
The stand includes the following panels shown in Fig. A2, a:

• Differential amplifiers to feed a computer by the feedback voltage
and current signals: A − load voltage 150 V B − supply voltage
150 V, C − supply current 2,5 V, D − load current 2,5 V connected as
shown in Fig. A2, b, c
• DC power supply of the Differential amplifiers and Universal control
unit with a control switch
• Universal control unit to set the required mode of operation − manual
or computer, to run/stop thyristor firing, and to adjust thyristors
manually by the set-point potentiometer
• Power converter unit built on thyristors and diodes
• Isolating transformer 3×400/3×2×47 V with a control switch
• Load 3×270 Ω, 2×0,3 H equipped with safety fuses and filament
lamps (Fig. A2, d, e)
• Multimeter to measure the rms values of voltages, currents, active
powers, reactive powers, apparent powers, and a power factor on
the supply side or to measure the dc and ac voltage components on
the load connected as shown in Fig. A2, b, c

Commonly, Differential amplifiers and Universal control unit are connected to
DC power supply permanently before the laboratory work implementations
whereas Multimeter and other panels are to be connected by the students. To
simplify the circuits assembling, the overlay masks may be placed above
Power converter unit before the work. Additional dc voltmeter PV measures
the load voltage.

To control the stand, computer with installed software PHACON may be used
or it may be performed manually with the set-point potentiometer of Universal
control unit. The required mode of operation is selected by the knob on
Universal control unit. Similarly, to examine the signal waveforms, PHACON
may be applied or an oscilloscope connected to the Differential amplifiers
panel. Before the computer measurements, the process should be calibrated
and tuned from menus Calibrate, Settings, and Chart. To plot the waveforms
on an oscilloscope, use the auto-tuning button or tune it manually.

23

Annexes

Multimeter
DC Universal Power Isolating
Diff. power control converter transformer Load
amps supply unit unit
Switch Mode Run Set-point Switch Switch

a. Panels of the stand

L1 2L1 R1

47 V Id Ud

I IU Power D A
400 V Load
converter 2 1 2 1
PS

47 V PV
N R2

b. Single-phase experimental circuit

400 V 47 V
2L1 R1
L1 Id Ud
U I I
D A
PS Power 2 1 2 1
L2 Load
converter
2L2
R2 PV
L3 2L3

c. Three-phase experimental circuit

270 Ω 270 Ω 0,3 H

d. Resistive load e. Inductive load

Fig. A2. Diagrams of stand “Line-commutated converters”

24

Annexes

3. Stand “Self-commutated converters”
The stand acts as an educational equipment produced by Lukas Nülle
Company to study self-controlled converters built on IGBTs. The stand
includes the following panels shown in Fig. A3, a:

• Differential amplifiers panel to feed the control equipment by the
feedback voltage and current signals: A − load voltage 400:2,5 and
D − load current 2,5:2,5 connected as shown in Fig. A3, b
• DC power supply panel with a control Switch
• Universal control unit panel to set the manual or computer operation
by the Mode knob, to permit IGBTs gating by the Run/Stop switch,
and to adjust IGBTs manually by the Set-point potentiometer
• Power converter unit panel built on IGBTs and diodes
• Isolating transformer panel 3×400/3×2×47 V with the control Switch
and the rectifier connected to the isolating transformer as shown in
Fig. A3, b, c
• Load panel 3×270 Ω, 2×0,3 H equipped with safety fuses and
filament lamps connected as shown in Fig. A3, d, e
• Multimeter PS to measure the average voltage, current and power of
the load connected as shown in Fig. A3, b

Commonly, the Differential amplifiers and the Universal control unit are
connected to the DC power supply permanently before the laboratory work
whereas the Multimeter and other panels are to be connected by the students.
To simplify the circuits building, the overlay masks may be placed above the
Power converter unit before the assembling. Additional dc voltmeter PV
measures the supply voltage.

To control the dc/dc converter, computer with installed software package
PWM may be used. Contrariwise, any dc/dc converter may be operated
manually with the Set-point potentiometer of the Universal control unit. The
required mode of operation is selected by the knob Mode. To examine the
signal waveforms, the PWM software package may be applied or an
oscilloscope may be connected to the Differential amplifiers panel. To
commencing the measurements on the computer, the process should be
calibrated and tuned using menus Calibrate, Settings, and Chart. To plot the
waveforms on an oscilloscope, use the auto-tuning button or tune it manually.

25

Annexes

Multimeter Power
DC Universal converter Isolating
Diff. power control Switch unit transformer Load
amps supply unit
Switch Mode Run Set-point Jumpers Switch

a. Panels of the stand
R1 R2 Id Ud
L+ 1Ω 1,8 Ω
2L1 D A
AC + 2 1 1 2
2L2 PV
DC - Power I U
2L3 L- Load
converter
PS

R3
8Ω

b. Experimental circuit

400 V 47 V 47 V
L1 2L1

L2 2L2

L3 2L3
c. Isolating transformer

270 Ω 270 Ω 270 Ω

d. Resistive load

270 Ω 270 Ω 270 Ω

e. Inductive load

Fig. A3. Diagrams of stand “Self-commutated converters”

26

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