AN ANALYTICAL MODEL FOR HYBRID VEHICLES DESIGN

<div class="htmlview paragraph">Hybrid electric vehicles (HEV) and other advanced propulsion technologies offer greater fuel economy and lower pollutant and tailpipe emissions. Some experts regard the HEV technology as a practical, attractive solution to social concerns about fuel economy (and related fossil fuel conservation) and vehicle emissions. [<span class="xref">Maples 98</span>] The technology is practical; however, an HEV is more expensive to produce than a conventional internal combustion engine (ICE). In a world of limited resources and many petroleum users and emissions sources, the policy question is whether the best use of resources is to build HEV, to improve the fuel economy and lower emissions from other sources, or to devote the resources to other environmental projects.</div> <div class="htmlview paragraph">We compare the second generation (designed for the United States) Toyota Prius, to the conventional internal combustion engine Toyota Corolla. We examine both private (vehicle purchase price, maintenance, and fuel) and social (the pollutant [non-methane organic gases, carbon monoxide, nitrogen oxides] and carbon dioxide emissions) costs. For each of the vehicles, we evaluate lifetime vehicle exhaust emissions as well as upstream emissions from producing the fuel.</div> <div class="htmlview paragraph">We find that the second generation Prius is still not cost-effective in improving fuel-economy and lowering emissions. For the Prius to be attractive to U.S. consumers, the price of gasoline would have to be more than three times greater than the present level. To be attractive to regulators, the social value of abating tailpipe emissions would have to be 14 times greater than conventional values. Alternatively, the value of abating greenhouse gas emissions would have to be at least $220 per ton. We judge that any HEV would have a difficult time competing with the Corolla because of the Corolla's already high fuel economy and low pollutant emissions.</div> <div class="htmlview paragraph">We also examine the costs and benefits of making a GM Silverado pickup truck into a gasoline hybrid. Like the analysis of the Prius, we again find that the price of gasoline or social value of abating carbon dioxide would have to be higher than the base case values in order to payback the cost of converting the vehicle to an HEV. Finally, we find that at current gasoline prices and carbon dioxide valuation, a conventional vehicle would need to have a fuel economy of 13 mpg or less in order for a $4,000 cost of converting it to an HEV to get 30% better fuel economy would pay off. We conclude that HEV will not have significant sales unless fuel prices rise several-fold or unless regulators mandate them.</div>

<div class="section abstract"><div class="htmlview paragraph">The overall efficiency of hybrid electric vehicles largely depends on the design and application of its energy management system (EMS). Despite the load coordination when operating the system in a hybrid mode, the EMS accounts for state changes between the different driving modes. Whether a transition between pure electric driving and internal combustion engine (ICE) powered driving is beneficial depends, among others, on the respective operation point, the route ahead as well as on the energetic expense for the engine start itself. The latter results from a complex interaction of the powertrain components and has a tremendous impact on the efficiency and quality of EMSs. Optimization based methods such as dynamic programming serve as benchmark for the design process of rule based control strategies. In case no energetic expenses are assigned to a state change, the resulting EMS suffers from being sub-optimal regarding the fuel consumption. However, an exact determination of such engine start costs has hardly been researched, yet leads to a more efficient EMS.</div><div class="htmlview paragraph">This paper focuses on the experimental evaluation of the energetic expense for engine starts in (plug-in) hybrid electric vehicles (P)HEVs under various conditions and the assessment of its impact on optimal EMSs. First, reproducible engine starts are performed on both a chassis dynamometer and a transient engine test bench for a wide speed and load range. The experiments are carried out for two plug-in hybrid test vehicles in a parallel driving configuration equipped with a 4- and 6-cylinder spark ignited (SI) engine. Subsequently, the results are discussed and broken down to the respective influence of individual powertrain components. Second, the start costs are embedded into a dynamic programming approach for EMSs as a function of the evaluated influencing parameters. The impact of the engine start costs is outlined by analyzing the optimal EMSs for a representative driving route.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Electrification of vehicles is an important step towards making mobility more sustainable and carbon-free. Hybrid electric vehicles use an electric machine with an on-board energy storage system, in some form to provide additional torque and reduce the power requirement from the internal combustion engine. It is important to control and optimize this power source split between the engine and electric machine to make the best use of the system. This paper showcases an implementation of the Adaptive Equivalent Consumption Minimization Strategy (A-ECMS) with minimization in real-time in the dSPACE MicroAutobox II as the Hybrid Supervisory Controller (HSC). While the concept of A-ECMS has been well established for many years, there are no published papers that present results obtained in a production vehicle suitably modified from conventional to hybrid electric propulsion including real world testing as well as testing on regulatory cycles. This paper details all the supportive algorithms that made this possible and the specific components to achieve the A-ECMS implementation and outlines design and performance details.</div><div class="htmlview paragraph">A-ECMS was tested for 1400+ miles of vehicle testing with 130,000+ miles on virtual environments (Model-in-Loop and Hardware-in-Loop) to determine the best calibration parameters for the battery-fuel equivalency factor and the penalties to achieve the best fuel economy. This strategy was implemented on a 2019 Chevrolet Blazer modified into a hybrid by The Ohio State University's EcoCAR team. Several comparisons are presented between the vehicle with A-ECMS and a stock vehicle. The project vehicle showed 6% fuel improvement in city cycles over the stock vehicle and 17% over the standardized FTP Drive Cycle on a two-axle dynamometer.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Increasing regulatory demand to reduce CO<sub>2</sub> emissions has led to an industry focus on electrified vehicles while limiting the development of conventional internal combustion engine (ICE) and hybrid powertrains. Hybrid electric vehicle (HEV) powertrains rely on conventional SI mode IC engines that are optimized for a narrow operating range. Advanced combustion strategies such as Gasoline Compression Ignition (GCI) have been demonstrated by several others including the authors to improve brake thermal efficiency compared to both gasoline SI and Diesel CI modes. Soot and NO<sub>x</sub> emissions are also reduced significantly by using gasoline instead of diesel in GCI engines due to differences in composition, fuel properties, and reactivity. In this work, an HEV system was proposed utilizing a multi-mode GCI based ICE combined with a HEV components (e-motor, battery, and invertor).</div><div class="htmlview paragraph">To determine the total fuel consumption over the FTP75 drive cycle, a fueling map from a multi-mode GCI combustion presented in a previous study was used as the input data set for the 1D HEV drive cycle model (GT Drive) of a mid-sized SUV. An HEV operation strategy was proposed and followed by parametric studies of components including the e-motor sizing (20 kW to 80kW) and the battery capacity (2Ah to 8Ah), and evaluation on their impacts on fuel consumption.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Reducing emissions and the carbon footprint of our society have become imperatives requiring the automotive industry to adapt and develop technologies to strive for a cleaner sustainable transport system and for sustainable economic prosperity. Electrified hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV) and range extender powertrains provide potential solutions for reducing emissions, but they present challenges in terms of thermal management. A key requirement for meeting these challenges is accurately to predict the thermal loading and temperatures of an internal combustion engine (ICE) quickly under multiple full-load and part-load conditions.</div><div class="htmlview paragraph">Computational Fluid Dynamics (CFD) and thermal survey database methods are used to derive thermal loading of the engine structure and are well understood but typically only used at full-load conditions. These methods are limited in terms of computational overhead with CFD and the validity of the database when wishing to look at part-load conditions to build up a thermal map of the engine for transient solutions.</div><div class="htmlview paragraph">This paper presents a new analytical Finite Element (FE) based tool for calculating thermal boundary conditions of all the components of the power cylinder using physical models and semi-empirical correlations, without the need for CFD analysis, and which overcomes the limitation of database methods which are not predictive. An iterative solution is used that captures all the heat paths in detail and where each solution runs quickly enough to allow different design variants to be assessed for multiple operating conditions. The calculated temperatures and the corresponding deformations can then be used to predict piston secondary motion and ring dynamics and to better predict friction, wear and oil consumption of the power cylinder and the structural durability of the components.</div><div class="htmlview paragraph">The toolset is applied to a 2.0 liter 4-cylinder Gasoline Turbocharged Direct Injection (GTDI) engine and validated with measurements on the piston, cylinder head and cylinder bore for different full and part-load conditions.</div></div>

In recent years, hybrid electric vehicles (HEVs) have increased significantly due to climate change and the demand for high-efficiency power sources. HEVs that combine an internal combustion engine (ICE) and an electric motor (EM) can improve the power output of the ICE and overcome the challenges of the insufficient battery life of electric vehicles. In this study, a parallel HEV with a power distribution mechanism is developed for energy saving and carbon reduction. The driver′s power demands are used as input sources, and a rule-based control strategy is used to determine the power distribution of the generator, EM, and ICE. The NEDC2000 driving cycle is used as the test benchmark to demonstrate the performance of the HEV. In comparison to ICE vehicles, the fuel efficiency of HEVs significantly improved. In addition, other parameters, including the average brake-specific fuel consumption (BSFC), brake-specific carbon monoxide emission (BSCO), and brake-specific hydrocarbons (BSHCs), were lower, which can effectively save fossil fuel and reduce air pollution.

<div class="section abstract"><div class="htmlview paragraph">This paper describes research focused upon improved the quality of automobile engine quality. Methods and models were developed for estimating and predicting the technical condition of internal combustion engine (ICE), which provides usage of the decision support making in the search for minimum fuel consumption regimes. We developed models of multi-criterion, multiparametric optimization of energy and material-material characteristics of ICE according to the system approach.</div><div class="htmlview paragraph">The developed methods and models for estimating and predicting the technical state of the functionally interconnected and interacting ICE components are performed taking into account their hierarchy and topologies, energy resource used and the fuel. The cognitive methodology has been used to make engine models researches and analysis. The paper focuses on the fuzzy logic approach applying, considering the indeterminacy, incompleteness and unclear information in the engines operation processes. Cognitive, imitation and fuzzy models for estimating and predicting the technical state of ICE have been developed by the authors of this paper, which allowed to identify ICE’s most vulnerable components, set weight values, influence on fuel consumption according to the quantitative and qualitative energy interchange between ICE components.</div><div class="htmlview paragraph">The received results provide quality enlargement of the ICE operation and their functional components, based on the developed estimation and prediction methods of their technical condition.</div><div class="htmlview paragraph">The paper describes results the cross-platform software application which was implemented using the high-level Java programming language and XML markup language. Developed software allows us to provide user’s flexible interaction process with the module of the decision support system, which is based on implementation of the developed methods and models for the ICE technical condition estimating and predicting.</div><div class="htmlview paragraph">Usage of the developed software helped to obtain optimization results of the energy and material characteristics of the explored ICE, which allows us to find several Pareto-optimal solutions for quality criteria that affect fuel consumption for each single model. This has led to a reduction of components wear, which leads to reducing fuel consumption during ICE operation.</div></div>

<div class="htmlview paragraph">As the community is becoming more and more aware and conscious of the pollution problems caused by the internal combustion engine and its use in transportation, we are now seeing the first projects and prototypes regarding hybrid and electrically-powered vehicles.</div> <div class="htmlview paragraph">One of the main problems witnessed by engineers has been that of the relatively low operating range provided by the storage batteries available on the market today, and so, recovering the energy that is inevitably lost during braking is of primary importance.</div> <div class="htmlview paragraph">The concept of regenerative braking is fairly simple as it consists in making the electric motors function as generators.</div> <div class="htmlview paragraph">In many of today's applications we find two indipendent controls for the operation of the hydraulic brake and for the activation of regenerative braking. The choice on which braking mode to use, or in which sequence the two modes are to be used is left to the driver who, at the onset of braking, is forced to make mental considerations in order to activate the two braking modes in the right sequence. Furthermore, the driver must not forget to disable the regenerative function at the end of each stop.</div> <div class="htmlview paragraph">BREMBO has designed a braking system in which a single control, that is, the brake pedal, activates and disables in the right sequence the two different braking modes, thus allowing:</div> <div class="htmlview paragraph"> <ul class="list disc"> <li class="list-item"> <div class="htmlview paragraph">to maximize energy recovery by the electric motors each time the driver steps on the brake pedal;</div> </li> <li class="list-item"> <div class="htmlview paragraph">the hydraulic brake to be used in addition to regenerative braking when the latter is not enough to produce the required deceleration.</div> </li> </ul> </div> <div class="htmlview paragraph">The proposed braking system is lightweight and versatile. It can be adapted to the different powertrain configurations seen on various electric vehicles.</div>

<div class="htmlview paragraph">While the ZEV program's electric vehicles did not become successful market-driven products, many of the technical advantages of electric vehicles were validated by enthusiastic California consumers. Yet, battery technology has been and continues to be the limiting factor in terms of cost, functionality (range) and durability of EV systems.</div> <div class="htmlview paragraph">The automotive industry has largely moved on to research and development of other approaches to extremely low emissions and reduced fossil fuel consumption. PZEV gasoline vehicles, Hybrid electric vehicles, clean (EPA Tier 2) diesel vehicles and Proton Exchange Membrane (PEM) fuel cell electric vehicles (FCEVs) are the focus of attention.</div> <div class="htmlview paragraph">The purpose of this paper is to explore another possible solution: a battery electric vehicle with a relatively small fuel cell auxiliary power unit (APU) to recharge the battery pack during driving. The attraction of this configuration is the use of a relatively small battery pack (to allow 65 - 110 km of ZEV range) while increasing vehicle range and functionality to be equivalent to conventional vehicles (400 - 650 km). Another key attraction is that a majority of km could be efficiently refueled from the grid allowing low or zero CO<sub>2</sub> power generating technology to be deployed in private transportation without the enormous cost and inefficiency of the H<sub>2</sub> infrastructure.</div> <div class="htmlview paragraph">The combination of Solid Oxide Fuel Cell (SOFC) APU and advanced Lithium Ion battery systems appears to make the fuel cell range extender EV an attractive system in terms of efficiency, weight and (in the midterm) cost. This paper will discuss the product attributes and advantages that such a system would bring to the customer and society and compare SOFC to Proton Exchange Membrane (PEM) fuel cell and other competing APU technologies. This paper will present system level assessment and analysis of the SOFC/Lithium Ion range extender EV applied to a GM EV1 platform.</div>

<div class="section abstract"><div class="htmlview paragraph">This simulation study explores the potential synergy between the HCCI engine system and three hybrid electric vehicle (HEV) configurations, and proposes the supervisory control strategy that maximizes the benefits of combining these two technologies. HCCI operation significantly improves fuel efficiency at part load, while hybridization aims to reduce low load/low speed operation. Therefore, a key question arises: are the effects of these two technologies additive or overlapping? The HEV configurations include two parallel hybrids with varying degrees of electrification, e.g. with a 5kW integrated starter/motor (“Mild”) and with a 10 kW electric machine (“Medium”), and a power-split hybrid. The engine is a dual-mode, SI-HCCI system and the engine map reflects the impact of HCCI on brake specific fuel consumption. The new HEV supervisory controller, called e-HCCI, is proposed considering two additional criteria: (i) maximize the time spent in the HCCI operating region, and (ii) minimize SI-HCCI mode transitions. The relative fuel economy improvements of using a dual-mode SI-HCCI engine over an SI engine for a conventional powertrain (non-hybrid) is 17%. When the dual-mode engine is used in the “Mild” HEV using the e-HCCI strategy, the percent improvement jumps to 35%. This indicates a strong synergy, and creates a very compelling case for the “Mild” parallel HEV w/ HCCI. Gains on a relative basis diminish somewhat with the “Medium” hybrid and significantly more with stronger power-split hybrids, as the latter typically moves engine load above the HCCI knock limit.</div></div>

<div class="section abstract"> <div class="htmlview paragraph">This SAE Recommended Practice identifies and defines requirements relating to the safe integration of the fuel cell system, the hydrogen fuel storage and handling systems (as defined and specified in SAE J2579) and high voltage electrical systems into the overall Fuel Cell Vehicle. The document may also be applied to hydrogen vehicles with internal combustion engines.</div> <div class="htmlview paragraph">This document relates to the overall design, construction, operation and maintenance of fuel cell vehicles.</div> </div>

<div class="section abstract"><div class="htmlview paragraph">An Air intake system (AIS) is a duct system which leads the airflow going into the internal combustion engine. Combustion requires oxygen, and the more oxygen is provided into the combustion process the more power it will produce. The lower the air temperature, the higher its density, and hence there is more oxygen in a unit volume. The quality of air entering engine can be measured with the air temperature.</div><div class="htmlview paragraph">AIS design and routing influence the air charge temperature (ACT) at intake manifold runners and ACT is normally measured at AIS throttle body in reality. Higher ACT lead to inefficient combustion and can lead to spark retard. Optimization of AIS designs and reduction of ACT can improve engine performance and vehicle fuel economy.</div><div class="htmlview paragraph">High ACT can be a result of two different phenomena: <ul class="list disc"><li class="list-item"><div class="htmlview paragraph">Recirculation - Hot air from the underhood environment ingested into the dirty side of the air intake system. This is the result of the AIS snorkel not being isolated or sealed from the engine compartment hot air.</div></li><li class="list-item"><div class="htmlview paragraph">Underhood temperature rise - Air inside AIS is heated by the ducts walls because it is routed through a hot underhood environment. The longer the length and larger the diameter of the air induction system, and the higher duct skin temperatures, the worse the temperature rise.</div></li></ul></div><div class="htmlview paragraph">In this paper, it is planned to simulate and study the effects of following factors on ACT with CFD using a FCA production vehicle: <ul class="list disc"><li class="list-item"><div class="htmlview paragraph">Snorkel location: snorkel sucking fresh air at side air guide or snorkel sucking underhood hot recirculation air.</div></li><li class="list-item"><div class="htmlview paragraph">Exhaust hot end at front of an east-west engine or at the rear of the engine; these two arrangements will result in different underhood air temperatures and radiation to AIS surfaces.</div></li><li class="list-item"><div class="htmlview paragraph">Heat shield effects on ACT: heat shield blocks radiation from exhaust system to AIS surfaces, and hence reduces charge air heat pick from AIS duct walls.</div></li><li class="list-item"><div class="htmlview paragraph">The effects of other measures such as cutting holes on hood or fenders to lower engine compartment air temperatures.</div></li></ul></div><div class="htmlview paragraph">Although the airflow in vehicle AIS duct is transient in nature, steady CFD simulations will be performed to study the above cases for simplification, and CFD approach will be discussed in details. Vehicle test data will be used to validate the CFD models.</div><div class="htmlview paragraph">Finally, general practices of AIS development will be discussed, and future work on this topic will be outlined.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Hybridization of vehicle drive train is an important step to increase energy security, reduce crude oil import, improvement of air quality and GHG reduction. Heavy traffic congestion poses a great challenge in improvement of fuel economy. Nowadays urban climatic condition forces the passenger to keep air-conditioning (AC) on; thus further decreasing the fuel economy. In a typical urban drive; the vehicle commutes with low speed forcing IC Engine to run in its low efficiency operational points. Further it is characterized by frequent start-stop and crawling. It has been observed that the power consumption for AC is comparable to that required for the vehicle propulsion. Hence the AC on condition with propelling vehicle demands higher power from engine creating a challenge for fuel economy improvement. It is observed in literature and simulation exercises that the fuel economy sharply falls with AC on condition in urban drive cycle and worsens in frequent start-stop and city traffic crawling. A study is required to study the improvement of fuel economy in a hybrid vehicle with AC on condition. Most of the work published in literature focuses on improvement in fuel economy with hybridization without air-conditioning operational.</div><div class="htmlview paragraph">The paper describes the techniques to improve fuel economy of a hybrid electric vehicle with AC on condition for a typical urban and city traffic crawling conditions. The hybrid configuration selected for study is a parallel hybrid with dual AC clutch which enables the drive of AC compressor by electric motor or IC Engine. Different hybrid control strategies for AC control, with compressor driven by IC engine alone; electric motor alone and blend of both were simulated for fuel economy on various city and city traffic drive cycles. The AC compressor drive control was based on vehicle speed; gradient requirement; Battery SOC; idle start-stop conditions and gear engaged. The control strategy parameters for IC Engine shut-off at different battery SOC levels; torque split quantity from both electric motor and IC engine for vehicle propulsion and AC compressor load sharing by electric motor and IC engine, based on battery SOC and vehicle demand were optimized to achieve maximum fuel economy. An improvement of 25-30 % in fuel economy was achieved with optimized AC control over the conventional vehicle in all city traffic conditions. All the simulations were done without downsizing the AC compressor; thus providing the same comfort to the passenger as experienced in conventional vehicles.</div><div class="htmlview paragraph">Thus it has been found out that optimized control of Dual clutch AC in hybrid vehicle plays a significant role in fuel economy improvement. The enhanced performance of the hybrid vehicle is achieved with keeping the AC capacity at par with the conventional vehicle.</div></div>

<div class="section abstract"><div class="htmlview paragraph">The rise of electric and hybrid vehicles with separate axle or wheel drives enables precise torque distribution between the front and rear wheels. The smooth control of electric motors allows continuous operation on high-resistance roads, optimizing torque distribution and improving efficiency. In hybrid vehicles, synergistic control of both internal combustion engines and electric motors can minimize energy consumption. Using the internal combustion engine for steady driving and electric power for acceleration enhances dynamic performance. Keeping the internal combustion engine at a constant speed is key to improving energy efficiency and vehicle responsiveness. The proposed method aids in selecting optimal power levels for both engines during the design phase. As acceleration time decreases, the ratio of electric motor power to internal combustion engine power increases. The torque distribution system, relying on sensors for axle loads, vehicle speed, and engine power, can reduce sensor numbers by correlating engine power with rolling resistance. Experimental results confirmed a 6.5% increase in engine power dedicated to acceleration due to reduced energy losses in the wheel drive, highlighting potential efficiency gains in hybrid vehicles.</div></div>

<div class="section abstract"><div class="htmlview paragraph">A highly efficient two-motor plug-in hybrid system is developed to satisfy the global demands of CO<sub>2</sub> reduction. This system switches three operation modes, what is called “EV Drive”, “Hybrid Drive” and “Engine Drive”, to maximize fuel efficiency according to the driving condition of the vehicle. Practical plug-in EV (Electric Vehicle) capability is also realized by adding a high-power on-board charger and a high capacity Li-ion battery to the original system.</div><div class="htmlview paragraph">The outlines of the system components including a newly developed Atkinson cycle engine, a highly efficient electric coupled CVT (Continuously Variable Transmission) with built-in motor and generator, an integrated PCU (Power Control Unit) and an exclusive battery for plug-in HEV (Hybrid Electric Vehicle) are described in this paper.</div><div class="htmlview paragraph">In addition to the switching of three driving modes and the efficiency improvement of each device, cooperative control of the hybrid system is introduced.</div><div class="htmlview paragraph">By installing this system in 2014 Accord plug-in hybrid, superior fuel economy is achieved with values of 46 MPG in CS (Charge Sustaining) mode and 115 MPGe (Miles Per Gallon equivalent) in CD (Charge Depleting) mode. 13miles of AER (All Electric Range) is also achieved while maintaining sufficient driving performance as a mid-size sedan.</div><div class="htmlview paragraph">MPGe is a unit of fuel economy for the alternate fuel vehicles such as plug-in hybrid or electric vehicles. The ratings are calculated by converting used electric energy into equivalent amount of gasoline.</div></div>