Hibrit araçların bileşenlerinin tasarımı, modellenmesi ve güç yönetim stratejisinin belirlenmesi
Design, modeling and determination of power management strategy of hybrid vehicle components
Yazar: MURAT FERHAT DOĞDU
Danışman: PROF. DR. İSKENDER ATİLLA REYHANCAN
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Enerji Bilim ve Teknoloji Ana Bilim Dalı / Enerji Bilim ve Teknoloji Bilim Dalı
Derece: Doktora, 2024
Konu: Makine Mühendisliği = Mechanical Engineering

Özet:
Günlük yaşamdan ticari faaliyetlere kadar önemli bir yere sahip olan ulaştırma sektörünün önemi küreselleşmeyle birlikte her geçen gün artmaktadır. Mevcut ulaşım sistemlerinde, enerji kaynağı olarak fosil yakıtları kullanan içten yanmalı motorlar, güç kaynağı olarak yaygın bir şekilde kullanılmaktadır. Motorlu taşıt sayısının önemli ölçüde artması; petrol kaynaklarının tükenmesi, hava kirliliği ve iklim değişikliği gibi sorunlara yol açarak hem çevre hem de insan sağlığını olumsuz etkilemektedir. Bu sebeple, otomotiv endüstrisindeki Ar-Ge çalışmaları araçların güç aktarma organlarının verimliliğinin artırılmasının yanında güncel emisyon standartlarını sağlama konusunda da yapılmaktadır. Geleneksel içten yanmalı motorlara sahip olan araçlara alternatif olarak sunulan elektrikli araçlar (EV) emisyon konusunda çözüm olsa da uzun şarj süreleri, şarj için altyapı eksikliği ve kısa menzil değerleri bu araçların yaygınlaşmasının önünde engel olmaktadır. Hibrit elektrikli araçlar (HEV), plug-in hibrit araçlar (PHEV), genişletilmiş menzilli elektrikli araçlar (E-REV) gibi teknolojilerin geliştirilmesi bu zorlukların üstesinden gelmeyi amaçlamakta ve elektrikli araçlara geçişte bir ara basamak olarak görülmektedir. Genişletilmiş menzilli araçlarda içten yanmalı motor batarya şarj seviyesi düştüğünde jeneratör görevi görerek bataryayı şarj eder.
Bu çalışma kapsamında bir menzil artırma ünitesi için gerekli bileşenler seçilerek bir deney düzeneği kurulmuştur. Sistemde kullanılmak üzere iki stroklu içten yanmalı motor tasarımı ve imalatı yapılmıştır. Motor için teorik ısıl analiz hesaplamaları yapılmıştır. Deneysel çalışmalarda farklı motor fren güçlerinde O2, HC, NO, NOx, CO, CO2 emisyon değerleri kaydedilerek karşılaştırılmıştır. Aynı zamanda erken ateşleme zamanlamasının (ateşleme avansı) indike güç, ortalama efektif basınç, yakıt tüketimi, ısıl verim ve motor performansı parametreleri üzerindeki etkisi araştırılmıştır.  
Diğer taraftan  MATLAB/Simulink yazılımda bir araç modeli geliştirilerek  benzinle çalışan bir araç ile menzil artırıcı üniteye sahip bir aracın performansları karşılaştırmalı olarak değerlendirilmiştir. Karşılaştırmalarda farklı hız-zaman profillerine sahip olan NEDC ve WLTC Sınıf 2 çevrimleri kullanılarak emisyon ve yakıt tüketimi değerlerindeki değişim incelenmiştir. Araştırma sonuçlarına göre menzil artırıcıya sahip bir aracın NEDC sürüş çevriminde CO2 emisyonu benzinli araca göre %3.3'lük bir artış gösterirken, WLTC Sınıf 2 çevriminde yakıt tüketimi %1.7 oranında artmaktadır. 
Geliştirilen matematiksel model ve geliştirilen mikro ölçek range extender sayesinde, yakıt tüketimi ve emisyonların etkisi detaylı olarak araştırılmış ve günlük hayatta yaygın olarak kullanılan bir benzinli motorlu araçla, aracın elektrikli ve range extender ile kullanılması sonuçları karşılaştırılmıştır. Bu sayede, range extender sisteminden elde edilen deneysel veriler ve yakıt tüketimi ve emisyon haritaları doğrudan taşıt modeline girilerek, elektrikli bir araç üzerindeki etkileri kapsamlıca araştırılmıştır. Diğer taraftan, menzil arttırıcı sistem ile batarya şarjı gerçekleştirilmiş bir elektrikli aracın emisyon ve yakıt tüketimi verilerinin konvansiyonel benzin tahrikli elektrikli araca göre nasıl değiştiği detaylı olarak araştırılmıştır. Zira, elektrikli araçların şarjı esnasında, gerek santrallerde, gerekse de iletim ve dağıtım hattında, gerekse de şarj istasyonlarında ciddi miktarda kayıplar olduğu bilinmektedir. Keza, menzil arttırıcı sistemlerin elektrikli aracın şarj edilemediği zaruri durumlarda kullanılacağı da göz önünde bulundurulduğunda, sistemin yakıt tüketimi ve emisyonlar açısından incelenmesi elzemdir. Elde edilen sonuçlardan, tez kapsamında geliştirilen menzil arttırıcı sistemin araçlarda kullanılabileceği ve elektrikli araçların kullanımı yaygınlaşana kadar ara çözüm olarak güvenli bir şekilde yararlanılabileceği sonucuna varılmıştır. Bununla birlikte, elektrikli araçlarda menzil arttırıcı çözüm olarak kullanılmasının seyir çevrimlerinde yakıt tüketimini benzinli araçlara göre çok az bir miktar arttıracağı ve emisyon ve yakıt tüketimi açısından bir problem oluşturmayacağı sonucuna varılmıştır. Elde edilen bulgularda, WLTC Sınıf 2 ve NEDC seyir çevrimlerinden çok düşük oranda CO2 ve yakıt tüketimini arttırması bu sonucu göstermektedir.

Abstract:
The transport sector, which plays a crucial role in both daily life and commercial activities, has gained increasing significance with the advent of globalization. This sector is vital for the movement of goods and people, facilitating trade and economic growth, and enhancing the connectivity of different regions. However, the widespread use of internal combustion engines that rely on fossil fuels as their primary energy source presents significant challenges. The proliferation of motor vehicles has led to several pressing issues, including the depletion of petroleum resources, air pollution, and climate change. These problems have far-reaching adverse effects on both the environment and human health, necessitating urgent action and innovation within the industry.
In response to these challenges, extensive research and development efforts are being undertaken in the automotive sector with the aim of improving the efficiency of vehicle powertrains and ensuring compliance with stringent emission standards. Traditional internal combustion engines, while reliable and powerful, contribute significantly to greenhouse gas emissions and urban air pollution. Therefore, there is a growing emphasis on finding alternative power sources that are more sustainable and environmentally friendly.
Electric vehicles (EVs) have emerged as a promising solution to the emissions problem. However, their widespread adoption is currently hindered by several limitations. One of the main drawbacks is the lengthy charging times required for EV batteries, which can be inconvenient for users. Additionally, the lack of a robust and widespread infrastructure for charging stations poses a significant barrier to the adoption of EVs. Limited driving range compared to conventional gasoline vehicles further complicates their acceptance by consumers who demand reliability and convenience.
To bridge the gap between traditional internal combustion engines and fully electric vehicles, the development of intermediate technologies such as hybrid electric vehicles (HEV), plug-in hybrid vehicles (PHEV), and extended-range electric vehicles (E-REV) is underway. These technologies are designed to mitigate some of the limitations associated with EVs while promoting a gradual transition towards cleaner and more sustainable transportation solutions. Hybrid vehicles, for instance, combine an internal combustion engine with an electric motor, allowing for improved fuel efficiency and reduced emissions. Plug-in hybrids offer the added advantage of being able to recharge their batteries through an external power source, thereby extending their electric-only driving range.
Extended-range electric vehicles (E-REV) take this concept a step further by incorporating an internal combustion engine that functions as a generator to recharge the battery when the battery charge level declines. This design allows for significantly extended driving ranges without the anxiety of running out of power, making them a practical choice for consumers who are not yet ready to fully commit to pure electric vehicles. By addressing the limitations of current EV technology, these range extender systems can play a crucial role in reducing environmental impacts and supporting the broader adoption of electric mobility.
In extended range vehicles, the internal combustion engine functions as a generator to recharge the battery when the battery charge level declines.
Within the scope of this study, the components required for a range extension unit were selected and an experimental setup was established. The experimental system comprises an internal combustion engine, an electrical control unit, and one BLDC as well as energy storage and measurement devices. The BLDC serves two purposes: it provides initial drive to the internal combustion engine and acts as a charging circuit for batteries, producing energy. 
A two-stroke internal combustion engine was designed and manufactured to be used in the system. and theoretical thermal analysis calculations were made for the engine. In the analysis, 6 engine cycles, namely 3000, 4000, 5000, 6000, 7000 and 8000, were evaluated. For each engine speed, the changes in effective power, effective torque, specific fuel consumption (BSFC) and effective thermal efficiency have been calculated as a function of engine speed.
An electronic control unit (ECU) has been developed, which is capable of controlling the ignition advance in accordance with the engine speed.
In the experimental studies, the emission values of O2, HC, NO, NOx, CO, CO2 were recorded and compared at different engine brake powers. Additionally, the impact of early ignition timing (ignition advance) on peak power, average effective pressure, fuel consumption, thermal efficiency and engine performance parameters was examined.
As the engine brake power increased, the amount of O2 produced by combustion decreased due to the enrichment of the fuel mixture. On the other hand, HC emissions increased significantly. Examining NO and NOx emissions, as expected, NO and NOx emissions increase with increasing cylinder pressures and temperatures with increasing engine load. Additionally, a slight increase in CO emissions was observed with increasing engine load. This can be attributed to the fact that, CO emissions tend to increase as a result of the formation of a richer fuel mixture with increasing engine load. Furthermore, CO2 emissions exhibited a notable increase as engine power increased in accordance with expectations.
On the other hand, a vehicle model was developed in MATLAB/Simulink software to evaluate the performance of a gasoline-powered vehicle and a vehicle equipped with a range extender unit. The model designed for the vehicle with a range extender unit differs in its configuration from that of gasoline-powered vehicles with the additional components; an electric motor, converter, and battery charge-discharge units. 
In order to examine the change in emission and fuel consumption values, NEDC and WLTC Class 2 cycles with different speed-time profiles were used in the comparisons. The results of the study indicated that CO2 emissions of a vehicle with a range extender increased by 3.3% in the NEDC driving cycle compared to the gasoline vehicle, while fuel consumption increased by 1.7% in the WLTC Class 2 cycle.
The findings indicate that integrating a downsized engine unit into an electric vehicle may result in slight increases in CO2 emissions and fuel consumption during specific driving cycles. These results emphasize the importance of optimizing range extender systems to minimize environmental impacts while providing necessary support for electric vehicles. Future research may focus on further enhancing the efficiency of these systems and addressing challenges related to emissions, fuel consumption, and overall performance to facilitate a smoother transition to sustainable transportation solutions.
The developed mathematical model and micro-scale range extender were employed to investigate the effects of fuel consumption and emissions in detail. The results of using a gasoline engine vehicle, which is widely used in daily life, with an electric vehicle and a range extender were compared. Experimental data obtained from the range extender system and fuel consumption and emission maps were directly entered into the vehicle model, enabling a comprehensive investigation of the effects of the range extender on an electric vehicle.
Conversely, a detailed investigation has been conducted into the impact of a range extender system on the emission and fuel consumption data of an electric vehicle. This is in comparison to a conventional gasoline-driven electric vehicle. It is acknowledged that there are significant losses during the charging process of electric vehicles, which occur at various stages, including in power plants, transmission and distribution lines, and charging stations. Similarly, in light of the fact that range extender systems will be employed in situations where the electric vehicle cannot be charged, it is imperative to examine the system in terms of fuel consumption and emissions.
The results of the study indicate that the range extender system developed within the scope of the thesis can be used in vehicles and can be used safely as an intermediate solution until the use of electric vehicles becomes widespread. However, it has been concluded that using electric vehicles as a range-extending solution will increase fuel consumption in cruising cycles slightly compared to gasoline vehicles and will not pose a problem in terms of emissions and fuel consumption. The findings indicate that this result increases CO2 and fuel consumption at a very low rate from WLTC Class 2 and NEDC cruise cycles.