common mode voltage and current reduction in voltage source inverter driven three phase ac ...

270 Pages·2007·13.14 MB·Turkish

COMMON MODE VOLTAGE AND CURRENT REDUCTION IN VOLTAGE
SOURCE INVERTER DRIVEN THREE PHASE AC MOTORS

A THESIS SUBMITTED TO
THE GRADUATE SCHOOL OF NATURAL AND APPLIED SCIENCES
OF
MIDDLE EAST TECHNICAL UNIVERSITY

BY

EMRE ÜN

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR
THE DEGREE OF MASTER OF SCIENCE
IN
ELECTRICAL AND ELECTRONICS ENGINEERING

NOVEMBER 2007
Approval of the thesis:

COMMON MODE VOLTAGE AND CURRENT REDUCTION IN VOLTAGE
SOURCE INVERTER DRIVEN THREE PHASE AC MOTORS

submitted by EMRE ÜN in partial fulfillment of the requirements for the degree of
Master of Science in Electrical and Electronics Engineering Department,
Middle East Technical University by,

Prof. Dr. Canan Özgen ____________
Dean, Graduate School of Natural and Applied Sciences

Prof. Dr. İsmet Erkmen ____________
Head of Department, Electrical and Electronics Engineering

Asst. Prof. Dr. Ahmet M. Hava ____________
Supervisor, Electrical and Electronics Engineering Dept., METU

Examining Committee Members:

Prof. Dr. Muammer Ermiş _______________
Electrical and Electronics Engineering Dept., METU

Asst. Prof. Dr. Ahmet M. Hava _______________
Electrical and Electronics Engineering Dept., METU

Prof. Dr. Nevzat Özay _______________
Electrical and Electronics Engineering Dept., METU

Assoc. Prof. Dr. Sencer Koç _______________
Electrical and Electronics Engineering Dept., METU

Dr. Erbil Nalçacı _______________
EPDK

Date: 27/11/2007

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I hereby declare that all information in this document has been obtained and
presented in accordance with academic rules and ethical conduct. I also declare
that, as required by these rules and conduct, I have fully cited and referenced
all material and results that are not original to this work.

Name, Last name : Emre Ün

Signature :

iii
ABSTRACT

COMMON MODE VOLTAGE AND CURRENT REDUCTION IN VOLTAGE
SOURCE INVERTER DRIVEN THREE PHASE AC MOTORS

Ün, Emre
M.S., Department of Electrical and Electronics Engineering
Supervisor: Asst. Prof. Dr. Ahmet M. Hava

November 2007, 246 pages

In this thesis various reduced common mode voltage (RCMV) pulse width
modulation (PWM) techniques and active/passive common mode voltage (CMV)
reduction methods for voltage source inverter driven three-phase AC motors are
theoretically and practically investigated. A novel RCMV-PWM method, the near
state PWM (NSPWM) method is proposed for operation at high modulation index.
At low modulation index, a modified version of an existing RCMV-PWM method,
AZSPWM1, termed as MAZSPWM, is proposed to mitigate the voltage reflection
problem of the method. An optimum modulation algorithm combining NSPWM and
MAZSPWM with seamless transition is proposed. The proposed RCMV-PWM
methods significantly reduce CMV but they suppress common mode current (CMC)
partially. Utilization of a common mode inductor together with RCMV-PWM
methods is effective in suppressing the CMC. In the study, in addition to the CMV
characteristics, various practical performance characteristics such as voltage
linearity, inverter output current ripple, inverter DC-link current ripple, and output
line-to-line voltage pulse pattern are also analyzed. The study involves analysis,
computer simulations, and detailed laboratory experiments.

Keywords: PWM, inverter, common mode, near state PWM, motor, EMI
iv
ÖZ

GERİLİM KAYNAKLI EVİRİCİLERLE SÜRÜLEN ÜÇ FAZLI ALTERNATİF
AKIM MOTORLARINDA ORTAK MOD GERİLİMİ VE AKIMININ
AZALTILMASI

Ün, Emre
Yüksek Lisans, Elektrik ve Elektronik Mühendisliği Bölümü
Tez Yöneticisi: Yrd. Doç. Dr. Ahmet M. Hava

Kasım 2007, 246 sayfa

Bu tezde gerilim kaynaklı eviriciden sürülen üç fazlı AC motorlar için çeşitli ortak
mod gerilimi düşürücü (OMGD) darbe genişlik modülasyon (DGM) yöntemleri ve
aktif/pasif ortak mod gerilimi (OMG) düşürücü yöntemler teorik ve pratik olarak
incelenmektedir. Yüksek modülasyon indisi bölgesi için yeni bir OGMD-DGM
yöntemi olan yakın komşu (YKDGM) yöntemi önerilmiştir. Düşük modülasyon
indisi bölgesinde, mevcut bir OMGD-DGM yöntemi olan AZSPWM1’in geliştirilmiş
hali olan MAZSPWM, yöntemin gerilim yansıması problemini gidermek üzere
önerilmiştir. YKDGM ve MAZSPWM yöntemlerini birleştiren ve geçişleri yumuşak
olan optimum bir modülasyon algoritması önerilmiştir. Önerilen OMGD-DGM
yöntemleri, OMG’yi etkin bir şekilde azaltmakta ancak ortak mod akımını (OMA)
kısmen bastırmaktadır. OMGD-DGM yöntemleri ile birlikte ortak mod indüktörünün
kullanılması OMA’yı etkili biçimde bastırmaktadır. Bu çalışmada, OMG
karakterstiklerine ek olarak, gerilim doğrusallığı, evirici çıkış akım dalgacığı, DC-
bara akımı dalgacığı ve faz-arası çıkış gerilimi darbe şablonu gibi değişik pratik
başarım karakteristikleride analiz edilmektedir. Bu çalışma, analiz, bilgisayar
benzetimi ve laboratuvar deneylerini kapsamaktadır.
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Anahtar Kelimeler: DGM, evirici, ortak mod, yakın komşu DGM, motor, EMI

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To my family

vii
ACKNOWLEDGMENTS

I express my sincerest thanks to my supervisor, Dr. Ahmet M. Hava, for his
guidance, support, encouragement, and valuable contributions throughout my
graduate education.

I would like to express my deepest gratitude to my family for their support.

I would like to express my deepest gratitude and respect to Dr. Tsuneo Kume for his
valuable comments and suggestions.

I would like to thank Mr. Turgay Halimler for providing the Yaskawa Varispeed G7
voltage source inverter utilized in this thesis.

Special appreciation goes to Ömer Göksu for the cooperation in the hardware of my
thesis; to Bülent Üstüntepe for his helps in DSP software coding; and to Eyyüp
Demirkutlu for reading and editing my thesis.

I would like to thank my reasearch groupmates Osman Selçuk Şentürk, Hasan
Özkaya, Mutlu Uslu, Süleyman Çetinkaya, Mehmet Can Kaya, and Fuat Onur
Bağlan for their help and support. I would also like to thank my officemates Atilla
Dönük, Naci Genç, and Seda Karadeniz and all my friends for their support.

I wish to thank to the Departmant of Electrical and Electronics Engineering faculty
and staff for their help throughout my graduate study.

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TABLE OF CONTENTS

ABSTRACT...............................................................................................................iv
ÖZ...............................................................................................................................v
DEDICATION..........................................................................................................vii
ACKNOWLEDGMENTS.......................................................................................viii
TABLE OF CONTENTS...........................................................................................ix
LIST OF FIGURES ..................................................................................................xii
LIST OF TABLES.................................................................................................xxiv

CHAPTER

1. INTRODUCTION................................................................................................1
1.1. Adjustable Speed Drives................................................................................1
1.2. Common Mode Voltage and Current.............................................................6
1.3. Scope of The Thesis ......................................................................................9

2. PWM METHODS AND CHARACTERISTICS................................................11
2.1. Introduction..................................................................................................11
2.2. PWM Basics, Scalar and Vector Implementations......................................13
2.3. Standard PWM Methods............................................................................. 16
2.3.1. Space Vector PWM (SVPWM) .......................................................18
2.3.2. Discontinuous PWM (DPWM) ....................................................... 20
2.4. Reduced Common Mode PWM Methods....................................................21
2.4.1. Active Zero State PWM (AZSPWM).............................................. 22
2.4.2. Remote State PWM (RSPWM)........................................................ 26
2.4.3. Near State PWM (NSPWM).............................................................30
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2.5. Performance Characteristics of PWM Methods .........................................35
2.5.1. Voltage Linearity..............................................................................36
2.5.2. Output Current Waveform Quality...................................................39
2.5.3. Inverter DC Link Current Ripple......................................................51
2.5.4. Inverter Output Line-to-Line Voltage Characteristics......................54
2.6. Combined Algorithm of PWM Methods.....................................................59
2.7. Summary .....................................................................................................60

3. INPUT AND OUTPUT CURRENT RIPPLE PERFORMANCE ANALYSIS OF
PWM METHODS BY MEANS OF COMPUTER SIMULATIONS................63
3.1. Introduction .................................................................................................63
3.2. Adjustable Speed Drive Simulation Model.................................................64
3.3. Simulation Results.......................................................................................67
3.3.1. Simulation Results at M = 0.61........................................................68
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3.3.2. Simulation Results at M = 0.9..........................................................94
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3.4. Simulations of the Combined Algorithm...................................................104
3.5. Summary....................................................................................................110

4. COMMON MODE VOLTAGE AND COMMON MODE CURRENT .........114
4.1. Introduction................................................................................................114
4.2. CMV in Different Inverter Topologies......................................................115
4.3. Common Mode Current Generating Mechanisms and The Bearing Currents
....................................................................................................................118
4.4. Factors Effecting CMCs............................................................................123
4.5. Common Mode Voltage and Current Mitigation Methods........................124
4.5.1. Common Mode Inductance (CMI)..................................................124
4.5.2. Common Mode Transformer (CMT) .............................................128
4.5.3. RLC Type Passive CM Filter..........................................................132
4.5.4. Active Common Mode Filter..........................................................133
4.5.5. Utilizing PWM Rectifier.................................................................134
4.6. CMV/CMC Reduction By Means of PWM Pulse Pattern Modification...136
4.7. Summary....................................................................................................136
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