Çamaşır makinası uygulamasında gan yarı iletkenanahtarlar ile yüksek güç yoğunluklu ve verimlievirici tasarımı
Design of high efficiency and high power densityinverter using gan semiconductors for washing machine
Yazar: TANER YAZICI
Danışman: DR. ÖĞR. ÜYESİ MURAT YILMAZ
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Elektrik Mühendisliği Ana Bilim Dalı / Elektrik Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2019
Konu: Elektrik ve Elektronik Mühendisliği = Electrical and Electronics Engineering

Özet:
Güç kaynakları ve motor tahrik sistemleri gibi güç elektroniği sistemleri gittikçe
yaygınlaşmakta ve daha önemli hale gelmektedir. Bunun sebebi güç elektroniği
sistemlerinin güç kontrolü, hareket uygulamaları, otomotiv ve kullanıcı elektroniği
gibi uygulamalarda sıklıkla kullanılmasıdır.
Son zamanlarda güç elektroniği sistemlerinde güç tüketimini azaltma ve güç
yoğunluğunu arttırma gibi gereksinimler, güç yarı iletken elemanlarının güç
kayıplarında ve anahtarlama frekanslarında iyileşme gerektirmektedir. Her ne kadar
silisyum anahtarlar güç elektroniği cihazlarında şu ana kadar önemli rol oynamış
olsalar da, yeni gereksinimler için silisyum malzeme limitlerine yaklaşmış
bulunmaktadır.
Geniş bant aralıklı yarı iletken malzemelerin mevcut silisyum teknolojisine göre daha
yüksek sıcaklıklarda, gerilimlerde, anahtarlama hızlarında ve daha düşük iletim direnci
gibi özellikleri vardır. Sonuç olarak, artık daha yüksek verim ve güç yoğunluğu
hedeflerini sağlamak için bu geniş bant aralıklı yeni nesil anahtarlar ile yeni tasarımlar
geliştirilmektedir.
Şu anda, silisyum karbür (SiC) ve galyum nitrür (GaN), üstün özellikleri,
malzemelerinin ticari olarak kullanılabilirliği ve teknolojik işlemlerinin olgunluğunun
bir sonucu olarak bu yeni geniş bant aralıklı yarı iletken malzemeler arasında
diğerlerine göre daha umut verici yarı iletken malzemelerdir. Hatta şu anda SiC ve
GaN anahtarları elektrikli araçlar ana tahrik, şarj istasyonları ve server gibi
uygulamalarda kullanılmaya başlanmıştır.
Bu çalışmanın ana konusu çamaşır makinası uygulamasında kullanılan IGBT tabanlı
motor kontrol kartı uygulaması referans alınarak aynı isterleri sağlayacak yeni bir GaN
anahtar tabanlı evirici tasarımı hedeflenmiştir. Çalışma sonunda ise iki farklı malzeme
teknolojine sahip motor kontrol kartları arasında farklı açılardan karşılaştırma
yapılmıştır.
Çalışmanın ikinci bölümünde çamaşır makinası uygulamasında kullanılan mevcut
motor, motor sürücü ve kullanılan motor kontrol yöntemi ele alınmıştır. Ayrıca
çamaşır makinasının yıkama çevrimleri, hız ve moment ihtiyaçlarına değinilmiştir.
Sonraki bölümde ise mevcut IGBT'li motor kontrol kartlı çözümün özellikleri
verilmiştir. Ayrıca bu uygulamada GaN kullanımının ne gibi avantajları olacağından
bahsedilmiştir.
Çalışmanın dördüncü bölümünde en sık kullanılan aktif güç elektroniği yarı iletken
elemanlarından bahsedilmiştir. Sonrasında ise SiC ve GaN anahtarların malzemesel
özelliklerine, türlerine ve silisyum tabanlı anahtarlar ise ne gibi farklılıları olduğuna
değinilmiştir. Malzemesel özellikler incelendiğinde mevcutta piyasada bulunan GaN
ve SiC anahtarların özelliklerinin çok daha iyileşeceği görülmektedir.xxii
Mevcut ve yeni nesil anahtarlar incelendikten sonra ise eviricinin elektriksel kayıpları
hesaplanmış, tasarlanan evirici için elemanların boyutlandırılmasından bahsedilmiş ve
devre blokları incelenmiştir. Ardından ise motor kontrol kartları ile yapılan osiloskop
ölçümleri, verim ölçüm testleri ve İletkenlikle Yayınım testlerinin sonuçları
verilmiştir.
Yeni tasarlanan kartın testlerinin yapılmasını ardından ise yapılan hesaplar ve testlerin
sonuçları karşılaştırılmış ve yorumlanmıştır.
Sonuç olarak bu çalışmada maksimum gücü 900W olan ve 230 V şebeke geriliminde
beslenebilen bir evirici tasarımı yapılmış, kart üretimiş ve çamaşır makinası üzerinde
test edilmiştir. Yeni nesil GaN anahtarlar ile tasarlanan eviricinin mevcut IGBT'li
eviriciye göre güç yoğunluğu ve verimde getirdiği iyileştirme ve soğutucu ihtiyacının
ortadan kaldırıldığı görülmüştür. Ancak kullanılan GaN anahtarlar IGBT anahtarlara
göre çok daha hızlı sürüldüklerinden dolayı EMC performansı açısından kötüleşme
görülmüştür. Bu durum ise bu tip yeni nesil anahtarlarda daha farklı tip ve spektrumda
daha farklı bölgelerde etkin filtre tasarımları ihtiyacının oluştuğunu göstermektedir.

Abstract:
In 1947 the first transistor was developed in the BELL laboratory. However, the use
of semiconductors in power electronics began in the late 1950s with the invention of
the thyristor. Thyristors were used in applications such as control of DC motors. The
disadvantage of the thyristors was that the they can not be turned off by controlling
gate.
The first power BJT switch was introduced in the 1960s. With the development of the
power BJT, the disadvantage of not being able to be turned off through the gate of the
thyristor has been overcome. In addition, studies on thyristors were continued and
GTO was developed which can be turned off by controlling gate with a special gate
design. In this way, higher powers can be controlled more efficiently. In 1970,
MOSFET was developed. MOSFETs are suitable for operation at higher switching
frequencies than BJT and thyristors due to their insulated gate, voltage control.
However, the disadvantage is that the power levels that can be used are lower than BJT
and thyristor in high voltage applications.
In the early 1980s, a new process was developed to integrate MOSFET and BJT
technologies into the same package. By this, IGBT switches were developed. With the
good aspects of both technologies, the IGBT switches replace BJTs at low and medium
power.
Power electronics systems such as power supplies and motor drives are becoming more
and more important because power electronics systems are frequently used in
applications like power management, motion control, automotive and user electronics.
Recent requirements like reduction of power cosumption and reduction of volume in
power electronic systems has led to improvements in power losses and switching
frequencies of power semiconductor components. Although silicon switches have
played an important role in power electronics so far, they have approached the silicon
material limits for new requirements.
Wide band gap semiconductor materials have properties such as higher operating
temperature, break-down voltage, switching speed and lower on resistance than silicon
technology. Due to their superior material properties, filter components and cooling
requirements can be reduced in power electronics circuits. In this way, power density
can be increased. Also, they may help to reduce total system's cost. As a result, new
designs are now being developed with this type of new generation switches to achieve
higher efficiency and power density targets.
Silicon carbide (SiC) and gallium nitride (GaN) are more promising semiconductor
materials than others among these new wide band gap semiconductor materials as a
result of their superior properties, commercial availability of materials and maturity ofxxiv
technological processes. Even now, SiC and GaN switches are used in electrical
vehicles such as main drives, charging stations and servers.
SiC switches have been extensively studied for the last 20 years. These semiconductors
switches are currently used in high power, high voltage and high switching frequency
applications on the market. Semiconductors designers are still optimizing SiC swithes
for lower switching loss and conduction losses.
GaN switches were first produced in 2004 for RF applications. Today, many different
companies have produced GaN switches with different power ratings up to 600 V.
Gallium Nitride crystal has a hexagonal structure called wurtzite. Chemically, this
structure is very robust at high temperatures can withstand material degradation.
The crystal structure of GaN has piezo-electric properties. Due to this feature,
electrical conductivity is higher than other semiconductor materials. When a thin
AlGaN layer is added on GaN material, the junction where the two materials join
becomes a highly conductive channel. This channel is called 2DEG (two dimensional
electron gas). 2DEG has high conductivity due to high electron density in a small
region on the surface. Unlike silicon switches, current flow is provided laterally from
the surface. This channel is normally on and bi-directional. It is not preferred for any
switches to be normally on in power electronics applications. Different solutions have
been produced and applied by different companies in order to keep the channel
normally off.
The main objective of this study is to design of a GaN-based inverter which will have
the same technical requirements with reference to the IGBT-based motor control
inverter used in the washing machine. Then, two different switching devices have been
compared according to the test results performed on motor control inverters.
In the second part of the study, the current motors, motor driver and motor control
methods used in washing machine application are discussed. In addition, washing
cycles, speed and torque requirements of the washing machine are mentioned. In this
way, the expectations from the motor drive in washing machine application have
become better understood.
In the next section, the specifications of the existing IGBT-based inverter and motor
are given. In addition, and experimental tests results for IGBT inverter are given and
the advantages of using GaN in this application are discussed. These results were used
when comparing IGBT based inverter with GaN based inverter.
In the fourth part of the study, the most commonly used active power electronics
semiconductor devices are mentioned. Afterwards, SiC and GaN switches have been
explained by their material properties, types and differences with silicon based
switches. When the material properties are examined, it is seen that the existing GaN
and SiC switches in the market are open to much more development in the future.
After examining the current and next generation switches, the electrical losses of the
inverter stage were calculated in order to perform thermal calculations. As the
calculated electrical losses were dramatically lower than the losses of IGBT-based
inverter, thermal calculations were performed without heatsink. According to the
calculations, the maximum junction temperature of the GaN switches was below the
maximum allowed junction temperature with a safety margin. For this reason, it was
seen that it was possible to remove the heatsink in the GaN based inverter.xxv
Motor control board is powered directly from the mains voltage. For field-oriented
control of PMSM, the amplitude, frequency and phase of the 3-phase voltage at the
output of inverter need to be controlled. Therefore, there is a need for rectified and
filtered dc voltage. For this, there is a full wave rectifier circuit at the input of the motor
control board. Also, some features of input stage: inrush current limitting consists of
relay and NTC, surge and over-current/short-circuit protection consists of VDR and
fuse, EMC filter consists of common mode choke and differential mode capacitor.
LMG3410 GaN Fets were used at inverter stage. This GaN FET has many internal
features like integrated gate driver, over-current protection, over-temperature
protection, under voltage lock out, transient over-coltage immunity, internal low dropout regulator and cascode configuration GaN. Integrating the GaN FET and gate driver
in same package is advantageous in high speed power electronics circuits. This is
because parasitic inductances of gate loop can cause extra switching loss, ringing and
reliability issues especially swithing at high slew rates of tens to hundrends of volts
per nanoseconds.
At the control stage, MC56F844 digital signal controller from NXP company was
used. This microcontroller is specially designed for three phase motor control
applications with many features for motor control applications like 3 phase
complementary PWM outputs and ADC-PWM synchronization.
After new motor control board was produced, some measurements have been taken
with oscilloscope on motor control inverters. Then, efficiency measurement tests and
conducted emission tests were performed for GaN based inverter.
After the measurements and tests of the GaN-based inverter were made, the analytical
calculations and the experimental results were compared.
As a result, in this study, an inverter with a maximum output power of 900W and
which can be supplied from 230 V mains voltage has been designed, manufactured
and tested on washing machine. It was shown that the designed inverter with the new
generation GaN switches, eliminates the heatsink by providing higher power density
and efficiency compared to the existing IGBT-based inverter. The total losses of the
inverter stage was reduced by 80% and the efficiency increased by 2.5%. Thus, the
need for heatsink was eliminated and the power density increased by a factor of 1.8.
On the other hand, the total cost of GaN based inverter increased by 6.1 times. The
main reason for this is that the cost of GaN switches is considerably higher than the
current silicon switches. However, semiconductor manufacturers assert that this high
price difference between GaN and silicon will decrease within the next 5 years. Also,
the EMC test results of the designed inverter has deteriorated due to the very high
speed of the GaN switches. This situation shows new filter designs that are more
effective in different spectrums are needed.