Harmonized Light Vehicles Test Cycle Research Articles

Dimensioning of a permanent magnet synchronous machine for electric vehicles according to performance and integration requirements

AbstractFinding the optimum design of electrical machines for a certain purpose is a time-consuming task. First results can be achieved, however, with scaling known machine designs in length and turns per coil by means of analytical equations, while scaling in diameter requires finite element analysis (FEA), since electromagnetic properties change significantly. In this paper, the influence of diameter, length and turns per coil on the torque, power and efficiency of a permanent magnet synchronous machine (PMSM) are investigated in a sensitivity analysis. Furthermore, their impact on energy consumption in different drive cycles and different vehicle types is outlined. A highway car and a city car are compared in a highway cycle, a city cycle and the Worldwide Harmonized Light Vehicle test Cycle. The results describe significant differences in energy consumption for different machine designs in one application but also between different applications. This highlights the necessity to decide whether or not the powertrain should be optimized for a single purpose or for universal use.

Effectiveness of the measures for CO2 emission reduction in real world

To reduce the CO2 emission level for the new Corporate Average Fuel Economy regulations, a series of measures are implemented by the manufacturers. Besides the use of hybrid and electric vehicles, efficiencies packages are frequently applied to improve the CO2 emissions of conventional vehicles. Some examples of CO2 reduction measures are: Start&Stop system, eco tires, powertrain thermal management and aerodynamic kits. Usually, they are optimized for the WLTC (Worldwide Harmonized Light Vehicles Test Cycle). The aim of this paper is to assess the influence of these packages in real-world driving cycles. The study is done by means of modelling and simulation, using an industrial modelling and simulation environment (LMS Imagine.Lab AMESim). Two passenger cars from different classes, a compact type and a SUV are used.

Developing local driving cycle for accurate vehicular CO2 monitoring: A case study of Tehran

Driving cycles used in legislation are fixed schedules of vehicle operation for standard emission evaluation of different vehicles. Recently, the growing deviation of CO2 values obtained with standard driving cycles from those recorded in real driving has prompted the development of new driving cycles to better estimate CO2 emission. International Council of Clean Transportation (ICCT) reports about a 40% deviation when vehicles are tested under New European Driving Cycle (NEDC). The introduction of Worldwide harmonized Light vehicles Test Cycles (WLTC) has reduced the gap between lab and road to 20%. However, this gap is predicted to grow until more robust tests based on real driving emissions (RDE) are presented for 2025 and beyond. This growing gap is a significant concern for reducing the carbon footprint in the transport section. The present article discusses developing local driving cycles for reducing this gap in passenger vehicles. Two distinct cycles with a good approximation of real driving were developed using the k-means clustering method. The CO2 emission of a 5-door passenger vehicle in these cycles was estimated using computer simulation. Compared with NEDC and WLTC, 30% less deviation from average CO2 emission levels recorded in real driving profiles was obtained with generated local driving cycles. The benefits of local driving cycles in legislation and reaching interim targets in reducing carbon emissions were discussed. The authors suggested implementing local driving cycles in type approvals without robust procedures based on real driving emissions. Granting subsidies to vehicles complying with local type approvals is also suggested as a stimulating policy for car manufacturers to boost overseas markets. It is concluded that replacing legislative driving cycles used for emission estimation with local driving cycles can significantly improve carbon reduction before implementing RDE into legislation.

Comparative study on fuel saving potential of series-parallel hybrid transmission and series hybrid transmission

The series hybrid transmission (SHT) and series-parallel hybrid transmission (SPHT) have become an important development direction in the field of hybrid electric vehicles (HEVs) in China. The main difference between a SHT and SPHT is that the engine can directly drive the vehicle through the addition of one clutch in the SPHT. The SPHT is thus more complex in structure, but its fuel economy advantages, as compared with the SHT, have remained controversial. Therefore, this study provides a thorough comparison between the SHT and SPHT for different types of vehicles and driving cycles. A global optimal control strategy based on dynamic programming (DP) is developed to evaluate the economic performance of the SHT and SPHT. Particularly, a mode-switching penalty matrix is designed in the control strategy based on the energy consumed during the mode-switching process. To exclude the influence of the configuration parameters and power sources, a large number of simulations are conducted for different parameter combinations. The results show that the SPHT has notable advantages in fuel saving compared with the SHT, especially in high-speed driving cycles for type C vehicles, while there is a negligible difference in the fuel consumption between the two for type A vehicles under urban driving cycles. Under the Worldwide Harmonized Light Vehicles Test Cycle (WLTC), the SPHT has a fuel saving of approximately 7.2% more than the SHT for type B vehicles. This study provides a new theoretical basis on technical path selection for the SHT and SPHT.

Studies on Energy Consumption of Electric Light Commercial Vehicle Powered by In-Wheel Drive Modules

This article presents the results of energy consumption research for an electric light commercial vehicle (eLCV) powered by a centrally located motor (4 × 2 drive system) or motors placed in the vehicle’s wheels (4 × 4 drive system). For the considered constructions of electric drive systems, mathematical models of 4 × 2 and 4 × 4 drive systems were developed in the Modelica simulation environment, based on real data. Additionally, the influence of changes in the vehicle loading condition on the operation of the motor mounted in the wheel and the energy consumption of the drive module was investigated. On the basis of the conducted research, a comparative analysis of energy consumption by electric drive systems in 4 × 2 and 4 × 4 configurations was carried out for selected test cycles. The tests carried out with the Worldwide harmonized Light vehicles Test Cycles (WLTC) test cycle showed a roughly 6% lower energy consumption by the 4 × 4 drive system compared to the 4 × 2 configuration.

Energy demand and emissions of a passenger vehicle fueled with CNG, gasohol, hydrous ethanol and wet ethanol based on the key points of the WLTC.

A compact sedan vehicle powered by a 1.4 dm3 spark ignition engine fueled with compressed natural gas (CNG), Brazilian gasoline, hydrous ethanol 95% v/v and wet ethanol 88% v/v was evaluated throughout the Worldwide harmonized Light vehicles Test Cycle (WLTC) key points. The vehicle operating points with longest residence time on the WLTC were selected to fuel consumption and emissions evaluation at steady state conditions. The top five key operating points reported in this work accounted for 22% of the total time spent in the entire cycle. The results indicated a significant reduction on greenhouse gases (GHG) emissions and energy demand for operation with CNG. The ethanol-water blends provided reduced emissions of nitrogen oxides (NOx), but increased specific fuel consumption, carbon monoxide (CO) and GHG emissions in comparison to CNG and gasoline. The operation with gasoline resulted in the minimum CO emissions for all fuels tested, as well as the best fuel consumption between liquid fuels, despite the highest values of carbon dioxide (CO2), and increased NOx. Even though ethanol produced little total unburned hydrocarbons (THC), the emissions of alcohols and aldehydes raised an alert for this renewable fuel, whereas CNG emitted the least amount of such pollutants.

Optimization of low carbon fuels operation on a CI engine under a simplified driving cycle for transportation de-fossilization

The study of internal combustion engines, and their associated energy conversion processes, is currently focused on targeting the reduction of pollutant emissions while maintaining or improving efficiency and fuel consumption. The research of alternative fuels, in particular low carbon fuels (LCF), seems to be a promising strategy for solving this problem. However, the characterization of a fuel with properties different than those of diesel requires numerous tests and resources to prove the viability of the substitution for another alternative. In Europe, for a vehicle to be homologated the World harmonized Light vehicles Test Cycle (WLTC) must be complied with. This cycle requires transient tests, that performed with a fuel for which an engine calibration is not yet existent would be difficult and could hinder the evaluation of the potential of a given fuel. This study proposes a cycle simplification methodology that seeks to reduce the driving cycle to a discrete set of stationary conditions, for which each operational calibration can be optimized. The optimization methodology is based on statistical analysis and modelling, and is presented to select the most desirable operating condition that can be reached using an LCF. For each testing point optimization NOx, soot, brake efficiency and fuel consumption are used as targets. Finally, the calibrated operating conditions are applied within the simplified cycle to assess the homologation potential of the studied fuel, as well as the equivalent CO2 emissions under the criteria of a well-to-wheel analysis (WTW).

Optimal Energy Management for Hybrid Electric Vehicles Based on Dynamic Programming and Receding Horizon

Fuel consumption and emissions in parallel hybrid electric vehicles (HEVs) are directly linked to the way the load request to the wheels is managed between the internal combustion engine and the electric motor powered by the battery. A significant reduction in both consumption and emissions can be achieved by optimally controlling the power split on an entire driving mission (full horizon—FH). However, the entire driving path is often not predictable in real applications, hindering the fulfillment of the advantages gained through such an approach. An improvement can be achieved by exploiting more information available onboard, such as those derived from Advanced Driver Assistance Systems (ADAS) and vehicle connectivity (V2X). With this aim, the present work presents the design and verification, in a simulated environment, of an optimized controller for HEVs energy management, based on dynamic programming (DP) and receding horizon (RH) approaches. The control algorithm entails the partial knowledge of the driving mission, and its performance is assessed by evaluating fuel consumption related to a Worldwide harmonized Light vehicles Test Cycle (WLTC) under different control features (i.e., horizon length and update distance). The obtained results show a fuel consumption reduction comparable to that of the FH, with maximum drift from optimal consumption of less than 10%.

Effect of oxidation temperature on oxidation reactivity and nanostructure of particulate matter from a China VI GDI vehicle

Modern Gasoline Direct Injection (GDI) vehicles offered higher power output, improved fuel economy and reduced CO2 emissions compared with port fuel injection (PFI) vehicles. However, the particle number emission of GDI is larger than that of PFI and also higher than diesel vehicles equipped with diesel particle filter (DPF). This research sampled particle matter (PM) emitted from a China VI vehicle over the Worldwide harmonized Light vehicles Test Cycle (WLTC). The results of particle size distribution showed that ultra-fine particles in diameter below 23 nm take up majority of particle emissions. While with the oxidation temperature rising, the peak diameter of emitted particles migrated to larger section. The effect of oxidation temperature including interlayer spacing, fractal dimension, fringe length and tortuosity have been analyzed by TEM. The value of nano structural parameters increases slightly with the temperature increasing. Besides, the impact of volatile components was considered into the micromorphology and microstructure parameters of primary particles. After eliminating volatile materials, there is no presence of hollow carbon particles and all the three parameters including interlayer spacing, fringe length and fringe tortuosity showed an overall decrease. Better understanding nano structural parameters of PM under different oxidation temperatures can provide information to explain the potential impacts of particle emissions on human health and environment and the regeneration process of gasoline particle filter (GPF).

Generation of a Real-Life Battery Usage Pattern for Electrical Vehicle Application and Aging Comparison With the WLTC Profile

The process of determination of batteries lifespan for a specific application generally contains some aging tests. Most of the time, these tests used simplified power or current profiles designed specially to be as representative as possible of the reality. The use of a real profile could improve the reliability of the approach but needs to know how to select the typical profile from an available database. This article shows the methodology used to analyze a database of 10 electric vehicles monitored during 2 years. Different mathematical methods (Pearson and Spearman coefficient of correlation, Shannon entropy, principal component analysis, K-means, ...) were applied to sort the essential variables and classify the uses of the vehicle. Representative classes of uses were then gathered to constitute a profile used in aging tests. The aging results with this real-life type profile and with an adjusted WLTC (Worldwide Harmonized Light Vehicles Test Cycles) profile are presented and compared. The effectiveness of the use of the WLTC profile for aging tests in real life automotive application is shown.

A cost and time effective novel methodology to determine specific heat capacity of lithium-ion cells

A cost and time-effective novel method for determining the specific heat capacity of prismatic and pouch lithium-ion cells using a simple setup and easily available equipment is presented in this paper. Specific heat capacity is an important thermal parameter of lithium-ion cells which is not readily available or provided by the cell manufacturers. The results found in this work are compared with the calorimetrically determined values of the specific heat capacity and a maximum error of 5% and 1.4% have been found for the pouch and the prismatic cells, respectively. The minimum error in the specific heat capacity for the pouch and the prismatic cells are 0.7% and 0.1%, respectively. The thermal parameters obtained using this methodology have been used to model the surface temperature of a prismatic cell during the application of a dynamic pulsed power as well as New European Driving Cycle (NEDC) and Worldwide harmonized Light vehicles Test Cycle (WLTC) drive cycles-based power traces. The excellent matching of the measured and simulated cell’s surface temperature during both the NEDC and WLTC drive cycles demonstrates that the thermal parameters determined using this new method can be used to model the surface temperature of the cell.

Cooling system based on double-ball motor control valve

To realize eco-models based on (where 3R represents reducing, reusing, and recycling), both researchers and automobile development departments use controllable components to reduce vehicle fuel consumption and emissions. In this context, this paper presents the design of a double-ball motor control valve (DB-MCV). When compared with use of a traditional thermostat, use of the proposed valve in a Worldwide Harmonized Light Vehicles Test Cycle (WLTC) allows the coolant temperature to be controlled accurately as per the vehicle operating conditions, with control accuracy of ±1°C. Using this approach, the engine pre-heating time is reduced by 61 s, the total hydrocarbon (THC)) emission is reduced by 6.79%, the CO emission is reduced by 7.18%, and NOX emission is reduced by 4.84%. Under the same vehicle and working conditions, the engine fuel consumption is reduced by 2.31% on average. Under the cabin heating condition, the cabin temperature can be increased by 4.3°C, which improves the thermal comfort of the driver. When the vehicle is stopped after running at high speed and the engine is idling, the coolant temperature in the engine decreases rapidly, which reduces the risk of a hot dip occurring in the engine.

Analysis of real-driving emissions from light-duty gasoline vehicles: A comparison of different evaluation methods with considering cold-start emissions

Cold-start emissions from road vehicles are an important source of air pollution. However, how to evaluate them in the real driving emission (RDE) test is controversial. Although the Commission Regulation (EU) 2017/1154 and 2018/1832 successively adopt the moving averaging window (MAW) method and the cumulative averaging (CA) method to calculate the emission factors that include the cold-start emissions in the RDE tests, both the methods have been found to be flawed when processing the RDE data including cold-starts. To demonstrate the problem, the RDE test data from three light-duty gasoline vehicles were comparatively analyzed using the MAW method and the CA method. Results reveal that the MAW method unreasonably underestimates cold-start emissions in the urban and total trip emission evaluation, and the CA method tends to increase the inconsistency of the RDE evaluation results. Considering the inherently different characteristics between the cold-start emissions and the non-cold-start emissions, this paper proposes that the entire RDE test trip should be divided into a cold-start trip and a non-cold-start trip, and the cold-start emissions are evaluated by the CA method while the non-cold-start emissions are evaluated by the MAW method. Furthermore, the pollutant emission factors in the cold-start trip are corrected referring to the CO2 emissions emitted during the cold-start period of Worldwide harmonized Light vehicles Test Cycle (WLTC). Using this proposed approach, the aforementioned RDE tests were further analyzed and evaluated again. It is verified that the consistency of the test evaluation results in the RDE tests can be improved. The results of this study could be used to improve future emission regulations for the more reasonable evaluation of cold-start emissions in RDE tests.

Investigation of the top compression ring power loss and energy consumption for different engine conditions

ABSTRACT The engine power losses and sealing behaviour through compression rings have become a priority for engine manufactures in view of future stringent emissions standards. Historically, compression rings have great application in small road vehicles and high-performance engines. The sealing behaviour of the compression ring has a significant effect on generated friction. Therefore, the lubrication conditions in the compression ring-liner conjunction should be addressed. This study comprises ring-liner mixed hydrodynamics using a two-phase flow and a gas blow-by model. This is implemented to investigate the characteristics of a high-performance top compression ring for different engine conditions. Low, medium, and high driving speeds are examined according to world-wide harmonized light vehicles test cycle. Additionally, the impact of lubricant temperature and compression ring width on power loss and fuel consumption are investigated to display the better engine performance.

Characterization of Particle Emissions of Turbocharged Direct Injection Gasoline Engine in Transients and Hot Start Conditions

Reducing pollutant emissions, particularly soot particles emitted by internal combustion engines, is a major challenge for car manufacturers. In this paper, the experimental setup is a turbocharged three-cylinders gasoline direct injection engine installed on a HORIBA dynamic test driven by a HORIBA STARS computer. The particle-measuring device is a Pegasor Particles Sensor that measures the current carried by previously electrically charged particles. The hot engine stabilized tests, with lambda parameter lower or equal to one, have very low emission levels, unlike dynamic tests. As a consequence, the present paper deals with experiments in transient conditions. Unlike diesel engine, cycle tests show that particulate emissions vary widely. To understand the phenomenon, a simple transient was created and reproduced a hundred times in order to obtain enough data to analyze and compare these different tests. This transient starts from idle to reach the speed of 2000 r/min and 60 N.m in 5 s. To reach this point, it is necessary to stay in full load for about 3 s. The maximum deviations of particles reaches 85% with the standard deviation σ=18%. The cylinder pressure sensor shows significant variations at the very beginning of each transient, i.e., during the first 500 ms. This kind of result was observed for Worldwide harmonized Light vehicles Test Cycles (WLTC) with a maximum deviations of particles reaching 75% with σ=30%, on Real Drive Emissions Cycle (RDE) with a maximum deviations of particles reaching 45% with σ=22% and for a 300 s Mini-Cycle with a maximum deviations of particles reaching 70% with σ=17%. The Mini-cycle is made up of the five largest accelerations of the WLTP cycle. A complete analysis highlights the importance of filling the first engine cycles. This depends on the opening speed of the throttle, the position of the crankshaft at the beginning of the transient, and the acceleration of the first cycles. But, the NOx sensor shows very slight variations between each test. As a consequence, it appears that the variation of particles emissions is not only related to variation of equivalence ratio but with another setting, which may be the oil consumption. Finally, from these results, it is possible to determine a particle characterization function. It consists of two functions. The first one is the average of the emitted particles level which depends on the engine speed, engine acceleration, engine torque and torque acceleration. The second function, which corresponds to dynamic variations in emissions, mainly depends on oil consumption in the cylinder and on the combustion quality of the first transient engine cycles.

Research on ammonia emissions characteristics from light-duty gasoline vehicles

In this study, ammonia emissions characteristics of typical light-duty gasoline vehicles were obtained through laboratory vehicle bench test and combined with New European Driving Cycle (NEDC) condition and Worldwide Harmonized Light Vehicles Test Cycle (WLTC) condition. The influence of ambient temperature on ammonia emissions is mainly concentrated in the cold start stage. The influence of ambient temperature on ammonia emission is shown that the ammonia emissions of light-duty gasoline vehicles under ambient temperature conditions (14 and 23°C) are lower than those under low ambient temperature conditions (−7°C) and high ambient temperature conditions (35 and 40°C). The influence of TWC on ammonia emission is shown that ammonia is a by-product of the catalytic reduction reaction of conventional gas pollutants in the exhaust gas in the TWC. Under NEDC operating conditions and WLTC operating conditions, ammonia emissions after the catalyst are 45 times and 72 times that before the catalyst, respectively. In terms of ammonia emissions control strategy research, Pd/Rh combination can reduce NH3 formation more effectively than catalyst with a single Pd formula. Precise control of the engine's air-fuel ratio and combination with the optimized matched precious metal ratio TWC can effectively reduce ammonia emissions.

Triple-screw pumps for ICE cooling systems in the transportation sector

Recent EU Regulations have been pushing the transportation sector increasingly towards the reduction of primary harmful pollutants and CO2 emissions. In this context, the Internal Combustion Engine (ICE) cooling system is gaining a new technological interest. In fact, improvements on pump efficiency can significantly reduce its absorbed energy during real on-the-road operation. Typically, centrifugal pumps are adopted, but their efficiency is highly dependent on rotational speed, wasting energy during real operation, even if they are designed to have a very high efficiency at the design point. This study investigates the three screws pumps potentiality to substitute traditional centrifugal pumps in engine cooling applications. In fact, triple-screw pumps belong to positive displacement pumps, which have an efficiency ideally independent on rotational speed.A zero-dimensional mathematical model of this pump previously developed by the authors was improved, giving a specific focus on the mechanical efficiency of the pump. The validation of the model resulted in a good agreement with experimental results. The model has been used to design a pump for an IVECO F1C diesel engine. The energy requested to drive the pump over a Worldwide Harmonized Light Vehicles Test Cycle (WLTC) has been calculated and compared with that of the traditional existing centrifugal pump. Results show that the electrically actuated triple screw pump allows to reduce the energy of about 14 %.

Particle Swarm Optimization and Real-Road/Driving-Cycle Analysis Based Powertrain System Design for Dual Motor Coupling Electric Vehicle

In this study, a planetary gear based dual motor coupling electric vehicle is proposed, which achieves higher system efficiency by enabling motor working under high operating efficiency area. Firstly, the dynamic characteristics of the proposed configuration are analyzed and the reasonable working modes are established. Secondly, the optimal dual motor parameters are derived according to the statistical analysis on the typical driving conditions and the collected real road driving data. Especially, the optimal parameters of planetary gear and final transmission ratio are obtained using particle swarm optimization algorithm. Finally, based on the developed mode shift algorithm, the dual motor coupling full vehicle model is developed and the vehicle performance is analyzed using MATLAB/Simulink. For the UDDS (Urban Dynamometer Driving Schedule) driving cycle, it is seen from the simulation results of motor operating points that the proposed dual motor configuration is mostly operated under the high efficiency range, and the power consumption is significantly reduced by 7.6% compared with the single motor configuration. For the NEDC (New European Driving Cycle), WLTC (Worldwide Harmonized Light Vehicles Test Cycle) and real road driving conditions, the proposed dual motor configuration also achieves system efficiency improvement of 5.0%~16.3%, which confirms the validity of the proposed configuration and its corresponding parameter matching and control algorithm development.

NOx sensor cross sensitivity model and simultaneous prediction of NOx and NH3 slip from automotive catalytic converters under real driving conditions

This work presents the development of a model to capture the NOx sensors cross sensitivity behavior based on [Formula: see text] sensor cell temperature, as well as a model do predict the slip of the NOx and NH3 after the SCR catalyst, as a way to reduce the error in the exhaust emissions estimation needed for feedback SCR control strategies. The emissions prediction model is based on the different cross sensitivity behavior of two distinct NOx sensors. The proposed models were tested and compared on a fully instrumented engine test bench when applied in a Worldwide harmonized Light vehicles Test Cycle (WLTC) and a full map cycle. As a result, the proposed model showed for NOx sensors cross sensitivity estimation an overall improvement of 34.8% for sensor 1 and 31.0% for sensor 2, and in terms of emissions prediction an overall improvement of 36.3% for NOx and 45.5% for NH3 slip.

Combined cycle gas turbine system optimization for extended range electric vehicles

In order to meet the Corporate Average Fuel Economy standards for passenger vehicles in 2025, car manufacturers are exploring several alternative energy converters to replace the Internal Combustion Engine, which has demonstrated limited efficiency improvement. Recent studies explored the use of a Gas Turbine as the primary vehicle driver in a hybrid powertrain; however, none evaluated the implementation of a Combined Cycle Gas Turbine, which offers higher efficiency. This study presents a methodology for the design and optimization of the most optimal combined cycle system configuration, suitable to replace the engine in a series-hybrid extended-range electric vehicle, and investigates its potential fuel savings. The two-steps methodology consists of conducting first an exergo-technological analysis using a Non-dominated Sorting Genetic Algorithm to identify the best suitable combined cycle configuration for integration in a series hybrid powertrain. Second, a series-hybrid extended range vehicle model is developed, to assess the consumption savings of the prioritized combined cycle on the Worldwide Harmonized Light Vehicle Test Cycle. The Reheat Gas Turbine combined to a Turbine Reheat Steam Rankine Cycle system is prioritized, for offering the highest efficiency and an acceptable vehicle integration complexity among the other investigated systems. Consumption results show fuel savings up to 23.6% with the prioritized system as compared to a reference extended-range electric vehicle equipped with an engine and savings up to 17% compared to other gas-turbine systems presented in the literature, depending on the battery size, the trip length, and the maximum turbine inlet temperature. Consequently, combined-cycle gas-turbine systems present a serious alternative to replacing internal combustion engines on series hybrid electrified vehicles if the cost-effectiveness of these systems was proven.