Realization of a direct soft switching AC/AC converter for wireless power transfer applications

96 Pages·2015·8.28 MB·English

by  Simo Vuorsalo

Aalto University
School of Electrical Engineering
Department of Electrical Engineering and Automation

Simo Vuorsalo

Realization of a Direct Soft Switching AC/AC
Converter for Wireless Power Transfer Applications

School of Electrical Engineering

Thesis submitted for examination for the degree of
Master of Science in Technology.
Espoo 13.11.2015

Thesis Supervisor: Professor Jorma Kyyrä

Thesis Advisor: M.Sc. Ferdi Kusumah
Aalto University
School of Electrical Engineering
Department of Electrical Engineering and Automation

ABSTRACT OF THE MASTER’S THESIS
School of Electrical Engineering
Master’s Programme in Electronics and Electrical Engineering
Author: Simo Vuorsalo
Title: Realization of a Direct Soft Switching AC/AC Converter for Wireless Power
Transfer Applications
Date: 13.11.2015 Language: English Number of pages: 95
Professorship: Power Electronics Code: S-81
Supervisor: Professor Jorma Kyyrä
Advisor: M.Sc. Ferdi Kusumah
This thesis describes the design, realization and testing of a three-phase to one-phase
direct AC/AC converter, also known as the matrix converter. The switching is using the
soft-switching strategy which is also known in the literature as the Zero Current
Switching strategy. To achieve ZCS, the circuit needs resonant behavior which is
achieved by the transmitter primary side that is an LC circuit. This circuit acts as a tank
circuit and the switching frequency is the resonant frequency of the LC circuit. The
design of the converter was done with OrCAD capture, PSPICE and Layout. The
proposed converter was designed completely during the project as well as the printed
circuit boards. The wireless power transfer is achieved by using an air-cored coil pair.
The receiver circuit analysis is not in the scope of this thesis.
The testing of the converter was not able to perform completely while the complexity
of the software prevented the project to be finished in given schedule. The partial test
results are shown in the thesis.

Keywords: Direct converter, Matrix converter, ZCS, Soft switching, Wireless power
transfer
ii
Aalto University
School of Electrical Engineering
Department of Electrical Engineering and Automation

DIPLOMITYÖN TIIVISTELMÄ
Sähkötekniikan korkeakoulu
Elektroniikan ja sähkötekniikan koulutusohjelma
Tekijä: Simo Vuorsalo
Työn nimi: Suoran AC/AC-muuttajan suunnittelu langattomiin tehonsiirtosovelluksiin
Päiväys: 13.11.2015 Kieli: Englanti Sivumäärä: 95
Professuuri: Tehoelektroniikka Koodi: S-81
Valvoja: Professori Jorma Kyyrä
Ohjaaja: DI Ferdi Kusumah
Tämä diplomityö käsittää suoran AC-AC –muuttajan toteutuksen, suunnittelun ja
testauksen. Muuttaja muuntaa kolmivaihesyötön yksivaiheiseen lähtöön. Kyseessä on
matriisimuuttajan eräs sovellus. Kytkentä toimii ns. pehmeällä kytkennällä, eli
kytkentähetkellä kytkimien virta on nollassa. Tämä saavutetaan kun kuormana toimii
kelan ja kondensaattorin sarjaankytkentä, jonka virta toimii myös takaisinkytkentänä
kytkinten ohjaukselle. Muuttajan langattoman tehonsiirron osuus toteutettiin
käytännössä ilmasydämisellä kelalla. Toteutus tehtiin tässä projektissa vain
ensiöpuolelle. Toisiopuolta ei tässä työssä käsitellä.
Suunnittelu toteutettiin OrCAD-ohjelmistolla. Suunnittelun kannalta oleelliset piirit
simuloitiin OrCAD PSPICE:llä. Lisäksi työssä esitetään komponenttiarvojen laskenta.
Toteutettu laite tehtiin osana projektia, jolloin laitetta varten tehtiin myös piirilevyt.
Muuttajan testausta ei ehditty tekemään loppuun annetussa aikamäärässä valmiiksi.
Syynä tähän oli hilaohjauksen monimutkaisuus, joka venytti ohjelmiston kehittämistä.
Osittainen testaus on esitetty työssä.

Avainsanat: suora muuttaja, matriisimuuttaja, langaton tehonsiirto
iii

Acknowledgments
I want to thank my advisor MS.c. Ferdi Kusumah who helped me significantly in order
to finish this thesis. Also, I want to thank Prof. Jorma Kyyrä for giving the opportunity
to join this incredibly interesting research project, and of course, all the help given
during the project. The feedback was valuable when the thesis was in progress.
I want to thank my former colleagues and co-students Marko Häkkinen and Konsta
Ruotsalainen, whom without I probably couldn’t have been able to finish my studies. I
wish them all the best during their final studies in Aalto University.

Espoo 13.11.2015

Simo Vuorsalo
iv

Table of Contents

ABSTRACT............................................................................................................................................... I
TIIVISTELMÄ .......................................................................................................................................... II
ACKNOWLEDGMENTS .......................................................................................................................... III
TABLE OF CONTENTS ............................................................................................................................ IV
ABBREVIATIONS ................................................................................................................................... VI
SYMBOLS ............................................................................................................................................ VIII
1 INTRODUCTION ............................................................................................................................. 1
1.1 WIRELESS POWER TRANSFER ............................................................................................................. 1
1.2 THESIS IN BRIEF............................................................................................................................... 3
2 DIRECT CONVERTERS AND COMPONENTS ..................................................................................... 4
2.1 MATRIX CONVERTER ........................................................................................................................ 4
2.2 MATRIX CONVERTER CLASSIFICATION .................................................................................................. 6
2.3 BI-DIRECTIONAL SWITCH ................................................................................................................... 6
2.4 DRIVING OF THE BI-DIRECTIONAL SWITCH ............................................................................................ 7
2.5 CONTROL OF MATRIX CONVERTER ...................................................................................................... 9
2.6 IGBT IN SOFT SWITCHING APPLICATIONS ........................................................................................... 11
2.7 POWER TRANSMISSION CIRCUIT ....................................................................................................... 13
2.8 PROPOSED DIRECT AC/AC CONVERTER ............................................................................................. 16
2.9 THERMAL CONSIDERATIONS ............................................................................................................ 17
2.10 ALTERNATIVE SWITCH COMPONENTS ................................................................................................ 18
3 DESIGN ........................................................................................................................................ 19
3.1 TECHNICAL DESCRIPTION ................................................................................................................ 19
3.2 PRIMARY RESONANT CIRCUIT DESIGN ............................................................................................... 21
3.2.1 Inductor ................................................................................................................................ 21
3.2.2 Capacitor .............................................................................................................................. 26
3.2.3 Resistor ................................................................................................................................. 27
3.3 SWITCHING COMPONENT ................................................................................................................ 28
3.4 IGBT DRIVER ............................................................................................................................... 31
3.5 MICROCONTROLLER ....................................................................................................................... 34
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3.6 VOLTAGE AND CURRENT MEASUREMENTS ......................................................................................... 36
3.6.1 Current Measurement .......................................................................................................... 36
3.6.2 Voltage Measurement ......................................................................................................... 37
3.7 THERMAL DESIGN .......................................................................................................................... 39
3.8 AUXILIARY COMPONENTS ................................................................................................................ 40
3.8.1 Contactor ............................................................................................................................. 40
3.8.2 EMI Filter .............................................................................................................................. 40
4 REALIZATION ............................................................................................................................... 42
4.1 RESONANT CIRCUIT ....................................................................................................................... 42
4.2 MEASUREMENT CIRCUITS ............................................................................................................... 44
4.2.1 Voltage Measurement Circuit .............................................................................................. 44
4.2.2 Current Measurement Circuit ............................................................................................... 44
4.3 SCHEMATICS ................................................................................................................................. 45
4.4 PCB ........................................................................................................................................... 46
4.4.1 PCB Specification .................................................................................................................. 46
4.5 COMPLETE PROTOTYPE ................................................................................................................... 46
4.6 MICROCONTROLLER AND SOFTWARE ................................................................................................. 47
5 TESTING ...................................................................................................................................... 50
5.1 FUNCTIONAL TESTING OF POWER SUPPLY .......................................................................................... 50
5.2 TESTING OF THE CONVERTER ............................................................................................................ 50
5.2.1 Test Equipment .................................................................................................................... 56
6 CONCLUSION ............................................................................................................................... 57
6.1 TESTING CONCLUSIONS .................................................................................................................. 58
7 FUTURE WORK ............................................................................................................................ 59
BIBLIOGRAPHY .................................................................................................................................... 61
APPENDIX A - SCHEMATICS ................................................................................................................. 64
APPENDIX B - LAYOUT ......................................................................................................................... 65
APPENDIX C – POWER SUPPLY TESTING .............................................................................................. 70
APPENDIX D - IGBT .............................................................................................................................. 75
APPENDIX E – IGBT DRIVER ................................................................................................................. 79

APPENDIX F – LITZ WIRE ...................................................................................................................... 83
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Abbreviations
AC Alternating current
ADC Analog-to-Digital Converter
CE Conformité Européenne
DC Direct Current
EMI Electromagnetic Interference
ESR Equivalent Series Resistance
EV Electric Vehicle
FOM Figure of Merit
HEV Hybrid Electric Vehicle
IC Integrated Circuit
IGBT Insulated Gate Bipolar Transistor
MC Matrix Converter
MCU Microcontroller Unit
OLEV On-Line Electric Vehicle
PCB Printed Circuit Board
RF Radio Frequency
SiC MOSFET Silicon Carbide MOSFET
TIM Thermal Interface Material
V2G Vehicle-to-Grid
WPT Wireless Power Transfer
VTR Voltage Transfer Ratio
ZCS Zero Current Switching
vii

ZVS Zero Voltage Switching
viii

Symbols
a,b Measures of an inductor, see Figure 13
A Area of the litz wire
WIRE
𝐶 Capacitance
Capacitance for primary and secondary. i = 1 for
𝐶
i
primary, i = 2 for secondary
𝐶 Primary Capacitance
P
d Litz wire diameter with insulation
0
d Litz wire diameter without insulation
l
d Optimum strand diameter of the litz wire
lopt
Diode reverse recovery energy of the soft switching
𝐸
DRR
IGBT
𝐸 Turn-off energy of the soft switching IGBT
IOFF
𝐸 Turn-on energy of the soft switching IGBT
ION
𝐸 Turn-off energy of an IGBT
OFF
𝐸 Turn-on energy of an IGBT
ON
𝐸 Reverse recovery energy of an IGBT
REC
𝑓 Resonant Frequency
0
𝐹 AC/DC resistance
R
𝑓 Resonant Frequency of the RLC circuit
RES
𝑓 Switching Frequency
SW
𝐼 Current
𝑖 i = 1 for primary, i = 2 for secondary
𝐼 Capacitor Current at nth frequency component
n
ix

Δ𝐼 Collector current change
C
Δ𝐼 Current change in an IGBT diode
D
𝑘 Coupling Factor
k Number of wire strands of a litz wire
litz
Inductance for primary and secondary. i = 1 for
𝐿
i
primary, i = 2 for secondary
𝐿 Primary Inductance
P
𝐿 Secondary Inductance
S
𝑀 Mutual Inductance
N Number of wire bundles of a litz wire
l
N Effective number of wire layers in a litz wire
ll
𝑃 Power loss of an IGBT during conduction
CI
𝑃 Gate Driver Power loss
GATE
𝑃 Capacitor power loss
H
𝑃 Total power loss of an IGBT
I
𝑃 Average power loss in 𝑊
LOSS Li
𝑃 Power loss of an IGBT diode during switching
SWD
𝑃 Power loss of an IGBT during switching
SWI
𝑄 Quality Factor
𝑄 Quality Factor of the Inductor
i
𝑅 Resistance
𝑟 Collector to emitter dynamic resistance
c
𝑟 Dynamic resistance of an IGBT diode
d
𝑅 Equivalent Resistance of the WPT system secondary
eq