Konvansiyonel bir ağır ticari vasıtanın elektrifikasyonu ve performans değerlendirmesi

Abstract

İçten yanmalı motorlara sahip araçların fosil yakıt tüketimi sonucunda atmosfere saldığı yanmamış hidrokarbon bileşenleri ve zararlı partiküller, çevresel kirliliğin artmasına, iklim değişikliğinin hızlanmasına ve küresel sera gazı salınımına etkisinin güçlenmesine yol açmaktadır. Bu sebepten dolayı, sıfır emisyon ve temiz enerji kaynaklarıyla çalışabilen elektrikli araçlara olan yönelim gün geçtikçe artmaya başlamıştır. Buradaki tez çalışmasının temel amacı da, içten yanmalı dizel motor ile çalışan bir ağır ticari taşıtın güç aktarım sistemini, bataryalı ve elektrikli güç aktarım sistemine dönüştürerek, aracın tamamen elektrikli bir kamyona evrimini modellemektir. Elektrifikasyon sürecinde, geleneksel kamyonun teknik özellikleri dikkate alınarak uygun elektrik motoru ve batarya hücresi seçimi yapılmıştır. Elektrikli kamyonun güç aktarım sistemini oluştururken iki temel model geliştirilmiştir: mekanik model ve elektrik modeli. Mekanik model içerisinde yer alan elektrikli aracın hız profilinin belirlenmesi, taşıta etki eden direnç kuvvetleri ve kullanılacak olan elektrik motorlar ilgili teknik hesaplamalar yapılmıştır. Bu hesaplamalar, elektrik modelinin ihtiyaç duyduğu güç ve performans gereksinimlerini belirlemiştir. Elektrik modeli, hesaplanan güç talepleri doğrultusunda batarya paketi ve elektrik motorunun uyum içinde çalışmasını sağlamak amacıyla geliştirilmiştir. Elektrifikasyon sürecinin doğru yönetilmesi, aracın modellenmesi ve analiz sonuçlarının doğruluğunu artırmakta, uygun bir güç aktarım sisteminin geliştirilmesini öncülük edecektir. Elektrikli kamyonun modellenmesi ve analizleri MATLAB/Simulink yazılımı kullanılarak gerçekleştirilmiştir. Simülasyon sürecinde, ileri yönlü yaklaşım metodu benimsenmiş ve model, aracın teknik parametreleri ile elektrik motoru ve batarya hesaplama sonuçları kullanılarak çalıştırılmıştır. Simülasyon sonuçları analiz edilerek, seçilen elektrik motoru ve batarya paketinin aracın performans gereksinimlerini karşıladığıyla ilgili validasyon yapılmıştır. Bu akademik çalışmada, teorik yöntemler kullanılarak geleneksel dizel motora sahip bir ağır ticari kamyonun belirlenen hız profilinde tükettiği yakıt miktarıyla elektrikli kamyonun aynı sürüş çevriminde harcadığı elektrik enerjisi hesaplanmıştır. Çalışmanın temel amacı, farklı güç aktarım sistemlerine sahip ağır ticari araçların harcanan enerji ile yakıt tüketimlerini karşılaştırarak, tahrik sistemlerinin verimliliklerini değerlendirmektir. Elde edilen veriler doğrultusunda, elektrikli güç aktarım sistemlerinin konvansiyonel dizel motorlara kıyasla daha yüksek enerji verimliliğine ve çevresel sürdürülebilirliğe sahip olduğu gösterilmiştir. Ayrıca, elektrifikasyon dönüşümü gerçekleşen bataryalı ağır ticari elektrikli taşıt ile referans çalışmadaki geleneksel dizel motora sahip ağır vasıta ekonomik açıdan karşılaştırıldığında, elektrik motora sahip güç aktarım sistemlerinin geleneksel dizel motora daha ekonomik olduğu kanıtlanmıştır.

In recent years, the environmental concerns associated with internal combustion engine (ICE) vehicles, particularly the emission of unburned hydrocarbons and harmful particulate matter from fossil fuel consumption, have significantly contributed to global pollution, climate change, and the intensification of the greenhouse effect. These adverse effects not only threaten human health but also pose a serious risk to environmental sustainability. As a solution, battery electric vehicles (BEVs) are increasingly considered a viable alternative to conventional vehicles due to their zero-emission capabilities and ability to utilize clean energy sources. Globally, freight transportation is carried out through various modes, including road, maritime, and air transport. Among these, road transportation, facilitated by trucks and heavy-duty vehicles, plays a crucial role in maintaining supply chains and ensuring the continuity of global trade. The transition of heavy commercial vehicles to electrified systems is essential for promoting sustainable transportation with clean energy sources. In this context, the primary objective of this study is to replace the power transmission system of a diesel-powered heavy commercial vehicle with a fully battery-electric powertrain, thereby transforming the truck into a fully electric commercial vehicle. Furthermore, this study aims to conduct a comprehensive analysis of the electrified heavy-duty truck, focusing on key performance metrics such as powertrain efficiency, environmental impact, and energy/fuel economy. A comparative assessment will be performed against a similar heavy-duty vehicle equipped with an internal combustion diesel engine to evaluate these aspects under identical operating conditions. By systematically comparing electric and conventional powertrain systems, this research seeks to demonstrate the superior advantages of electrified commercial vehicles in terms of energy efficiency, sustainability, and overall performance. During the electrification process, a detailed selection of an electric motor and battery cells was conducted to match the technical specifications of the conventional truck. The powertrain of the electric truck was modeled using two fundamental structures: the mechanical model and the electrical model. In the mechanical model, the vehicle's operating speed profile was first established, followed by the definition of key vehicle parameters to align with the selected heavy commercial truck configuration. The resistance forces acting on the truck, including rolling resistance, aerodynamic drag, and grade resistance, were formulated and integrated into the vehicle dynamics analysis. These parameters were utilized to compute the required traction force and power demand for various operating conditions. The final stage of mechanical modeling involved verifying the compatibility of the selected electric motor's technical parameters with the calculated mechanical properties. This process ensured an optimal balance of torque, power, and rotational speed, enabling the electric truck to achieve the desired acceleration and sustain efficient operation under full-load conditions. The results obtained from the mechanical model represent the vehicle's performance and power demand. Based on these outcomes, the required electrical energy is determined and requested from the electrical model. The electrical model was developed to ensure the compatibility of the battery pack and electric motor in delivering the required power output. Additionally, battery pack configuration—including series and parallel cell arrangements, physical structure planning, and electrical performance analysis—was conducted to establish an optimal propulsion system. Proper management of the electrification process is critical for enhancing the accuracy of dynamic analysis and modeling results, ensuring the development of a robust and efficient power transmission system. The modelling and dynamic analysis of the electric commercial truck were conducted using MATLAB/Simulink software. In the MATLAB/Simulink environment, vehicle modelling could be performed using two fundamental approaches: forward approach method and backward approach method. In this study, the forward approach method was employed to model the electric commercial truck. The 'Vehicle Dynamics Blockset' module available in MATLAB/Simulink provides pre-configured blocks for essential components such as the vehicle body, wheel dynamics, electric motor, battery system, Proportional-Integral (PI) controller, and drive cycle components. By integrating these predefined components, the electric vehicle model was developed, and the parameters and results obtained from previous sections were systematically incorporated into the respective Simulink blocks. Throughout the simulation process, key performance indicators would be analyzed, including the total distance traveled (range), battery State of Charge (SoC), changes in current and voltage values, and the comparison between the reference speed and the actual vehicle speed. These analyses would be conducted to validate whether the electric motor could draw sufficient energy from the battery to effectively propel the vehicle. In this study, theoretical formulations were employed to assess the performance, efficiency, environmental impact, and energy/fuel economy of both the electrified heavy-duty truck and its conventional counterpart powered by an internal combustion diesel engine (ICE). These formulations were systematically implemented in Microsoft Excel to enable an accurate comparative analysis. The electrified truck model incorporated technical parameters such as the MATLAB/Simulink analysis results, specifications of the electric motor and battery system, and resistance forces affecting the vehicle. These parameters were essential for accurately simulating the truck's real-world performance under different driving conditions. For the conventional diesel truck, engine data and experimental parameters from relevant studies were integrated into Microsoft Excel to conduct the necessary ICE calculations. This approach ensured a standardized and data-driven comparison between the electrified and conventional heavy-duty trucks. The findings derived from these calculations are presented and analyzed in the subsequent section. The findings of this study present a detailed comparison between the electrified heavy-duty truck and its conventional diesel-powered counterpart. The results were obtained through various computational analyses, employing separate tables and graphical representations to illustrate energy consumption and economic outcomes. The energy consumption and cost analysis of the electrified heavy-duty truck under loaded and unloaded conditions were evaluated. The comparison in Tables demonstrates a significant variation in energy consumption between the fully loaded and unloaded scenarios. Since load factor has a substantial impact on energy consumption, optimizing vehicle payload is crucial for energy efficiency. Based on the MATLAB/Simulink simulations, the electric truck was calculated to cover 36.9 km within the defined drive cycle. As the vehicle load increases, the power demand from the electric motor rises, leading to a proportional increase in energy consumption per kilometer. Operating costs for electric heavy-duty trucks depend on both unit electricity pricing and total energy consumption. In this study, calculations were performed using DC charging tariffs to determine both the per-kilometer energy cost and total cost analysis. Additionally, battery capacity and corresponding charging costs at different load conditions were assessed to estimate the charging station costs associated with the given battery capacity. All results presented in Tables were obtained through MATLAB/Simulink and Excel-based virtual simulations under different loading conditions. The efficiency map of the electric motor under the HHDDT drive cycle, as simulated in MATLAB/Simulink. The map was developed based on the predefined motor speed (rpm) and the corresponding torque values, providing insights into the motor's operational efficiency under different conditions. The electric motor maintains a high efficiency of approximately 96% across a wide range of speeds and torque levels. The efficiency map was developed using the input parameters of torque and motor speed, modeling it as a 1-D look-up table that returns efficiency values based on real-time operational conditions. Before comparing the electrified heavy-duty truck with its conventional diesel-powered counterpart, an operational analysis of the internal combustion engine truck was conducted, with results presented in diesel engine's Table. The conventional engine selected for this study is a 7.33-liter, 6-cylinder diesel engine with 240 PS at 2400 RPM and 840 Nm of torque between 1200–1800 RPM, utilizing a Bosch Common Rail Injection system with turbocharging and an intercooler (TCI). The reference driving cycle and predefined conditions were used to evaluate the fuel consumption and fuel economy of this heavy-duty diesel truck across different engine speeds, as detailed in diesel engine's Table. For diesel engine's table, fuel consumption, total power output, and economic metrics were analyzed across five different engine speeds. Additionally, this study compares the obtained results with those from the electrified truck, enabling an assessment of the operational efficiency of the internal combustion engine. The specific fuel consumption (SFC) varies between 199–214 g/kWh, depending on engine speed. A detailed fuel consumption analysis was conducted based on engine operating time. The SFC vs. Engine Speed belongs the graphical representation in this study illustrates the relationship between specific fuel consumption (g/kWh) and engine speed (RPM) under full-load conditions, providing insight into the efficiency trends of the diesel engine across various operating ranges. For the same HHDDT drive cycle, fuel consumption per kilometer was analyzed while maintaining the same driving range for accurate comparison. Diesel Engine's Table indicates that fuel consumption per kilometer decreases as engine speed increases, suggesting a more cost-efficient operation at higher speeds. When assessing the relationship between specific fuel consumption and power output, results indicate that fuel consumption decreases up to a certain power level but increases again beyond this threshold. The graph of SFC-Power demonstrates that power demand initially grows inversely with fuel consumption, but at higher power levels, fuel consumption becomes directly proportional. Last graphic presents the torque vs. engine speed relationship of the diesel engine under full throttle conditions. At full throttle, the combustion chamber receives the maximum air-fuel mixture, which forces the engine to operate at maximum load. This figure provides insights into the correlation between engine torque and speed, as well as the impact of fuel consumption at full load conditions. The comparative analysis between the electrified heavy-duty truck and the conventional diesel truck highlights significant differences in energy consumption, operational efficiency, and cost-effectiveness. The results demonstrate that the electrified powertrain offers superior efficiency, particularly in terms of energy economy and sustainability, making it a viable alternative for future heavy-duty transportation applications.