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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

8

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 :


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

10

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

11

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




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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

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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

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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

15



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

17

III.2.3 Full – bridge converter


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




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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

20

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



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

23

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

24

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

25

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

27

Figure 4.6 Top layer

Figure 4.7 Bottom layer


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CHAPTER IV

28

Figure 4.8 : Control circuit in real

Figure 4.9 : Control Pulse for IGBT


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CHAPTER IV

29

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

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