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i
Vietnam National University, Ho Chi Minh City
Ho Chi Minh City University of Technology
Faculty of Electrical & Electronic Engineering
Excellence Engineers Training Program in Vietnam---------------o0o---------------
GRADUATION ESSAY
DESIGN AC VOLTAGE STABILIZER
SINGLE PHASE USING AC –
AC CONVERTER
Instructor: Dr. NGUYỄN ĐÌNH TUYÊN Student : NGUYỄN ĐỨ C NGUYỆ N
HCM city, 6 /2015
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CONTENT
ii
CONTENT
CHAPTER I : INTRODUCTION ............................................................................. 1
CHAPTER II : AC voltage stabilizers ...................................................................... 2
II.1 Coil-rotation AC voltage regulator ............................................................. 2
II.2 Electromechanical ...................................................................................... 3
II.3 PWM voltage regulator (PWM) ................................................................. 4
CHAPTER III: AC – AC CONVERTERS AND USING IN VOLTAGESSTABILIZERS .......................................................................................................... 5
III.1 The principle of operation of the AC - AC converter for voltage
stabilization ........................................................................................................... 5
III.2 AC - AC converter ........................................................................................ 6
III.2.1 Buck converter : .................................................................................... 6
III.2.2 Half - bridge converter : ......................................................................... 9
III.2.3 Full – bridge converter ......................................................................... 17
CHAPTER IV : DESIGN A VOLTAGE STABILIZER WITH HALF – BRIDGESUPPLIDE ON LINE SIDE ................................................................................... 22
IV.1 Selecting components ................................................................................. 22
IV.2.1. The control circuit ............................................................................... 22
IV.2.2 The Power circuit ................................................................................. 22
IV.3 Design Circuit using Orcad 9.2 ................................................................... 24
IV.3.1 Design the Controller ........................................................................... 24
IV.3.2. Design Power circuit ........................................................................... 29
REFERENCE .......................................................................................................... 31
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CHAPTER I
1
CHAPTER I : INTRODUCTION
Power quality describes the quality of voltage and currenta facility has, and is one of the
most important considerations in industrial and commercial applications today. It is essential that
processes, in particular, in industrial plants, operate uninterrupted where high productivity levels
are an important factor. Power quality problems commonly faced by industrial operations
include transients, sags, swells, surges, outages, harmonics, and impulses that vary in quantity or
magnitude of the voltage. Of these, voltage sags, extended undervoltages and overvoltages have
the largest negative impact on industrial productivity, and could be the most important type of
power quality variation for many industrial and commercial customers
Some major problems associated with unregulated line voltages (in particular, long-term
voltage sags) include equipment tripping, stalling, overheating, and complete process shutdowns.
These subsequently lead to lower efficiencies, higher power demand, higher cost for power,
electromagnetic interference to control circuits, excessive heating of cables and equipment, and
increased risk of equipment damage. The need for line voltage regulation still remains a
necessity to meet demands for high industrial productivity.
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CHAPTER II
3
II.2 Electromechanical
Electromechanical regulators called voltage stabilizers or tap-changers, have also been used to
regulate the voltage on AC power distribution lines. These regulators operate by using
a servomechanism to select the appropriate tap on an autotransformer with multiple taps, or by
moving the wiper on a continuously variable auto transfomer. If the output voltage is not in the
acceptable range, the servomechanism switches the tap, changing the turns ratio of the
transformer, to move the secondary voltage into the acceptable region. The controls provide
a dead band wherein the controller will not act, preventing the controller from constantly
adjusting the voltage ("hunting") as it varies by an acceptably small amount.
Figure 2.2 : Voltage stabilizer with transformer and servo motor
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CHAPTER II
4
II.3 PWM voltage regulator
This is the latest technology of voltage regulation to provide real-time control of voltage
fluctuation, sag, surge and also to control other power quality issues such as spikes and EMI/RFI
electrical noises. This uses an IGBT regulator engine generating pulse width modulated (PWM)
AC voltage at high switching frequency. This AC PWM wave is superimposed on the main
incoming wave through a buck-boost transformer, to provide precisely regulated AC voltage.
The regulation in this technology is instantaneous, thus making it suitable for electronic
machines which need precise regulated power.
Figure 2.3 : Voltage Stabilizer
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CHAPTER III
5
CHAPTER III: AC – AC CONVERTERS AND USING IN VOLTAGES
STABILIZERS
III.1 The principle of operation of the AC - AC converter for voltage
stabilization
Configure the AC - AC converter based on the basic configuration as buck, half - bridge, full -
bridge ... combined with an output transforme.r The converter incorporates fast-switching
insulated gate bipolar transistor (IGBT) technology, and controls involving pulsewidth
modulation (PWM) techniques. The model block diagram is shown in this fig
B)
Figure 3.1 Model block diagram of the ac voltage – voltage converter system.
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CHAPTER III
6
III.2 AC - AC converter
III.2.1 Buck converter :
a) Configuration and control algorithms
Figure 3.2 Configuration and control algorithms
There will be two states depends on the sign of the source voltage,
Where Vi> 0, S1 and S2 switching pulse while S3 and S4 is always enabled
Where Vi 0 :
When DTs S1,S3,S4 on, S2 off:
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CHAPTER III
7
Figure 3.3. Equivalent circuit in DTS where Vi >0
Then VL = Vi
When (1 – D)Ts S2,S3,S4 on, S1 off:
Figure 3.4 Equivalent circuit in (1 – D)TS Vi >0
Then VL = 0
Where Vi < 0 :
When DTs S1,S2,S4 on, S3 off:
Figure 3.5. Equivalent circuit in DTS Vi
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CHAPTER III
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When (1 – D)Ts S2,S1,S3 on, S4 of:
Figure 3.6. Equivalent circuit in (1 – D)TS where Vi
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CHAPTER III
9
Voltage quality depends on the selection of capacitors and inductors, in a certain range,
the ratio VL/Vi D, if L and large C will affect this rate.
We choose the value inductors and capacitors based on criteria in the ripple current and
ripple voltage at capacitors
III.2.2 Half - bridge converter :
a) Configuration and control algorithms
Figure 3.9 Configuration and control algorithms
b) Switching analysis
Assuming that the switching frequency is f s periodTs
1.
Where Vi > 0 :
a. When DTs S1,S3,S4 on, S2 off:
Equivalent circuit
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CHAPTER III
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Figure 3.10 Equivalent circuit in DTs when Vi > 0
Then Vo = -Vi/na
b. When (1- D)Ts S2,S3,S4 on, S1 off:
Equivalent circuit
Figure 3.11 Equivalent circuit in (1 – D)Ts when Vi > 0
Then Vo = Vi/nb
Calculate the RMS voltages when Vi > 0
Vo = Vi(
)
Vi
2.
Where Vi < 0 :
a. When DTs S1,S3,S2 on, S4 off:
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CHAPTER III
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Figure 3.12 Equivalent circuit in DTs when Vi < 0
Then Vo = -Vi/na
b.
When (1- D)Ts S2,S1,S4 on, S3 off:
Figure 3.13 Equivalent circuit (1 – D )Ts when Vi < 0
Then Vo = Vi/nb , similar in Vi > 0 , we have
Vo =
Vi
So Vo = Vi
We choose the value inductors and capacitors based on criteria in the ripple current and
ripple voltage at capacitors
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CHAPTER III
12
c)
Simulation Half – bridge by PSIM
Figure 3.14 Control Pulse in a period voltage
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CHAPTER III
13
a)
b)
Figure 3.15: Output voltages: a) before using filter b) after using filter
Comment : with a defined Transformer ( na and nb is constant ) we can modulate
opposite in phase voltage or same phase with source voltages this mean we can use this
converter in voltage regulator to increase or decrease output voltage by voltage superposition
method
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CHAPTER III
14
d)
Vol tage Regulator using Half - bridge
Figure 3.16 Half – bridge voltage regulators supplied on line side
Control algorithms is base on Half – bridge converter.
We have VL = Vi + V
Replace V by Vi base on ratio output/input of Half – bridge converter
VL Vi
For calculater the value na and nb of transformer we use
And
Replace VL by Vi we have
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CHAPTER III
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We choose the value inductors and capacitors based on criteria in the ripple current and
ripple voltage at capacitors
e) Simulation Voltage regulator by PSIM
Figure 3.17 Output voltages while source voltage change
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CHAPTER III
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Figure 3.18 At setting time
Comment : In the transitional period, the overshoot is not too high, in the setting time the
error can be negligible
Conclusion : Half - bridge AC - AC converter with supplied on line side configuration
can be applied to the voltage regulator in fact, combined with PI closed-loop control for almost
exactly the result, high quality .
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CHAPTER III
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III.2.3 Full – bridge converter
a) Configuration and control algorithms
Figure 3.19 Configuration and control algorithms Full – bridge converter
b) Switching analysis 2 level
When Vi > 0 : with S5,S6,S7,S8 always on we have
+Vi : S1 and S4 on in the same time, S2 and S3 off
-Vi : S2 and S3 on in the same time , S1 and S4 off
When DTs S5,S6,S7,S8,S1,S4 on, S2,S3 off:
Equivalent circuit
Figure 3.20 Equivalent circuit in DTs when Vi >0
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CHAPTER III
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Then Vo=Vi
When (1 – D)Ts S5,S6,S7,S8,S2,S3 on, S1,S4 off:
Figure 3.21 Equivalent circuit in (1 – D)Ts when Vi >0
Then Vi
Where Vi < 0 :Similar in Vi >0
We have
Vo= DVi - (1 – D) Vi = (2D – 1 )Vi
We choose the value inductors and capacitors based on criteria in the ripple current and
ripple voltage at capacitors
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CHAPTER III
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c)
Simulation Full – bri dge 2 level by PSIM
Figure 3.22 Control Pulse
a)
b)
Figure 3.23: Output voltage of full – bridge 2 level, a) before using filter, b) after using filter
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CHAPTER III
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d)
Use fu ll – bri dge 2 level in Voltage Regulator
Figure 3.24 Full - bridge supplied on load side
Control algorithms is base on Full – bridge converter
We have VL = Vi + V
Replace V by Vi base on ratio output/input of Full – bridge converter
VL Vi
For calculater the value n of transformer we use
And
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CHAPTER III
21
Replace VL by Vi we have
We choose the value inductors and capacitors based on criteria in the ripple current and
ripple voltage at capacitors
e)
Simulation by PSIM
Figure 3.25 Output voltage with source voltage change
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CHAPTER IV
22
CHAPTER IV : DESIGN A VOLTAGE STABILIZER WITH HALF –
BRIDGE SUPPLIDE ON LINE SIDE
IV.1 Selecting components
IV.2.1. The control circuit
DSP TMS320F28069 for PWM and PI control
IC 7407 and IC 3120 for driver and isolation circuit
Voltage sensor LV25P for read the feedback voltages
IV.2.2 The Power circuitUsing Half – bridge supplied on side line, with this parameter :
Vi = 220 ± 20% V, ( = 0.2)
Vo = 220 V, Io 5 A
Power 1kW;
Transformer:
Calculate na and nb follow this formulas
Figure 4.1 Transformer fo Half – bridge .
With = 0.2 we have na = 4 và nb = 6, to secure we choose na=3.5 và nb = 5.
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CHAPTER IV
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Other factor
V pmax = 270V (rms) Vs1max = 77V (rms) Vs2max = 54V(rms)
I p max = 3A (rms) Is1max = 3.3 A (rms) Is2 max = 8 A (rms)
IGBT G60N100
Figure 4.2 IGBT G60N100
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CHAPTER IV
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IV.3 Design Circuit using Orcad 9.2
Circuit will be divided into 2 parts
Controller
Power circuit
IV.3.1 Design the Controller
The control circuit will have board of DSP, driver and isolation circuit, feedback voltage
circuit. Using Orcad Capture to draw principle diagram
Figure 4.3 Driver and isolation circuit for one PWM
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CHAPTER IV
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Figure 4.4 Driver and isolation circuit
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CHAPTER IV
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Figure 4.5 Feedback voltage circuit
Using Orcad Layout to draw PCB circuit with 2 layer, we have
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CHAPTER IV
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Figure 4.6 Top layer
Figure 4.7 Bottom layer
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CHAPTER IV
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Figure 4.8 : Control circuit in real
Figure 4.9 : Control Pulse for IGBT
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CHAPTER IV
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IV.3.2. Design Power circuit
The Power circuit will have : the connections, IGBT, capacitor, inductor
Figure 4.10 Power circuit
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CHAPTER IV
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And PCB circuit with one layer
Figure 4.11 PCB of Power circuit
For some objective reasons so I can not finish on time power circuit
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REFERENCE
REFERENCE
[1] T. Shinyama, A. Ueda, and A. Torri, “AC chopper using four switches,”
in Proc. PCC , Apr. 2002, pp. 1056 – 1060.
[2] Steven M. Hietpas “Automatic Voltage Regulator Using an AC Voltage –Voltage Converter” IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL.36, NO. 1, JANUARY/FEBRUARY 2000
[3] Thiago B. Soeiro, Clovis A. Petry “Direct AC– AC Converters Using Commercial PowerModules Applied to Voltage Restorers” IEEE TRANSACTIONS ON INDUSTRIALELECTRONICS, VOL. 58, NO. 1, JANUARY 2011
[4] C van Schalkwyk, H.J. Beukes and H du T Mouton “AN AC-TO-AC CONVERTER BASED
VOLTAGE REGULATOR” IEEE Africon 2002
[5] Jin Nan , Tang Hou-jun, Liu Wei and Ye Peng-sheng “Analysis and Control of Buck -BoostChopper Type AC Voltage Regulator ” Power Electronics and Motion Control Conference,2009. IPEMC '09. IEEE 6th International
[6] Texas Instruments Co
C2000™ MCU 1 -Day Workshop, February 2012
TMS320x2806x Piccolo Technical Reference Manual, March 2014
TMS320C28x Optimizing C/C++ Compiler v6.4 User's Guide, November 2014
SN5407, SN5417, SN7407, SN7417 HEX BUFFERS/DRIVERS WITH OPEN-
COLLECTOR HIGH-VOLTAGE OUTPUTS , DECEMBER 1983 – REVISED NOVEMBER 2000
[7] Avago Technologies Co , HCPL-3120/J312, HCNW3120 2.5 Amp Output Current IGBT
Gate Drive Optocoupler datasheet , October 16, 2013
[8] LEM Co , Voltage Transducer LV 25-P datasheet, 20 November 2012