Harmonized Light Duty Test Cycle Research Articles

Power Management Strategy for the 48 V Mild Hybrid Electric Vehicle Based on the Charge-Sustaining Control

To enhance the 48 V mild hybrid electric vehicle performance using a smaller capacity and lower voltage battery than the full hybrid electric vehicle, a novel power management strategy needs to be established that considers the characteristics and limitations of the components. This paper proposes a charge-sustaining control strategy as a ground principle of the 48 V hybrid electric vehicle control for managing the battery state-of-charge (SOC) to stay near the most efficient regime. The base efficiency characteristics of the component models including engine, motor/generator, and battery are determined in the form of efficiency maps using the powertrain analysis tool. Then the control strategy is formulated as a nonlinear optimal regulation problem that meets two conflicting control objectives, such as fuel efficiency improvement and state-of-charge maintenance. The optimal regulation problem implements a discrete-time Hamilton-Jacobi-Bellman approach. The proposed strategy is evaluated by comparing with the reference strategy applying the Dynamic Programming (DP), i.e. a global optimal result, under urban dynamometer driving schedule and worldwide harmonized light duty test cycle. Through the evaluation, the fuel efficiency of the proposed strategy with three different electrical loads is slightly deteriorated at most by 5.03 % from the DP results with staying within a desirable SOC. This suggests that the proposed strategy is operating very closely to global optimal performances.

Impact of counter-bore nozzle on the combustion process and exhaust emissions for light-duty diesel engine application

This article describes the main results of an investigation about counter-bore injector nozzle impact on the combustion process in a modern Euro 6 diesel engine. First, hydraulic and spray visualization tests have been performed, showing a potential advantage of such nozzle design in fuel–air mixing efficiency. Then, combustion performance has been assessed on a GM-designed 1.6-L four-cylinder engine. The engine has been installed on a dynamometric test bench and instrumented with an AVL cylinder pressure transducer for heat release rate analysis, as well as HORIBA MEXA gas analyzer for exhaust emissions and AVL 415 Smoke Meter. Engine efficiency and emissions have been analyzed on four different part-load steady-state points, representative of New European Driving Cycle and Worldwide harmonized Light duty Test Cycle certification cycles, and covering engine speeds from 1250 to 2000 r/min and brake mean effective pressure between 0.2 and 1.4 MPa. Results of indicated analysis show that counter-bore nozzles have significant differences in terms of pilot injection combustion at low load points, which in turn lead to a better ignition and shorter combustion of the main injection. In addition, an improvement of diffusive combustion is observed as load increases. Because of both, fuel consumption is reduced by approximately 1% with respect to a standard nozzle. Finally, an appreciable decrease in engine exhaust emissions has been recorded, especially in terms of particulate matter and hydrocarbon emissions. This reduction has been linked to the improvement of fuel–air mixing promoted by the counter-bore nozzle previously observed.

Terengganu routes representation for development of Malaysia Driving Cycle: Route selection methodology

A program to develop a harmonized light duty test cycle that will represent typical conditions for Malaysia is going to be developed, named Malaysia Driving Cycle (MDC). The development of MDC will adapt the methodology from the worldwide harmonized light duty driving test cycle (WLTC). Terengganu has been chosen as one of the regions for in-use driving data collection. In developing MDC, the route selection phase must be carried out first before proceeding to the route data collection. This paper describes briefly on the methodology used for the route selection, the selected routes and the driving conditions for route data collection in Terengganu region. Road Traffic Volume Malaysia (RTVM) version 2015 and Google Maps are used to study the route selection in Terengganu region. By adapting the methodology of WLTC, 11 routes in the Terengganu region have been selected to contribute the speed-time data for development of Malaysia Driving Cycle (MDC). The selected routes consist of urban, rural, and motorway road. For the route data collection, the driving conditions (peak, off-peak, weekend) are considered to collect the samples for each route and direction.

Comparative analysis of automatic transmission and manual transmission behaviour on the worldwide harmonized light duty test cycle

The European Commission has been actively involved in the development of the World-wide harmonized Light duty Test Cycle (WLTC). The aim of that project was to develop a harmonized light duty test cycle, that represents the average driving characteristics around the world and to have a legislative world-wide-harmonized procedure put in place from 2017 and onwards for determining the level of CO2 emissions. This work presents the results of the effect of automatic and manual transmissions as a drivetrain of a light duty vehicle on WLTC driving cycle. AVL Cruise software was used as simulation platform to analyse the CO2 level and fuel consumption of dynamic vehicle model using different type of drivetrains. At first the simulation tool and the most influential parameters of the driving cycle procedure are described. In the second phase various components and modules for both dynamic models using automatic and manual transmission, as well as the respective input parameters, were defined. Analyses are based on a developed dynamic vehicle model in AVL Cruise. Finally, the simulation results were evaluated and presented for the two dynamic models according to a legislative driving cycle to provide the basis fuel consumption and exhaust gas emissions.

Comparative analysis of automatic transmission and manual transmission behaviour on the worldwide harmonized light duty test cycle

Comparative analysis of automatic transmission and manual transmission behaviour on the worldwide harmonized light duty test cycle

Binomial multifractal features of worldwide harmonized light duty vehicles test cycle

Driving tests that have been performed for many years are not representative of actual vehicle operating conditions in terms of emissions and fuel consumption. This paper presents the research results of a new Worldwide harmonized Light duty Test Cycle (WLTC), that takes into account situations occurring in traffic inside and outside the city and on highways in Europe, India, Japan, Korea and USA. Conducted analysis demonstrated a multifractal nature of vehicle speed time signal, typical for he processes of asymmetric generalized multiplicative cascade.

CO2 emissions and energy demands of vehicles tested under the NEDC and the new WLTP type approval test procedures

The European Commission has been actively involved in the development of the World-wide harmonized Light duty Test Cycle (WLTC) and corresponding Test Procedure (WLTP), and is currently working to introduce them in the European type approval (TA) procedure. The present study analyzes and estimates the effects of the introduction of WLTP on the average CO2 emissions and average vehicle energy demands (VEDs) from different segments of the European vehicle market. Twenty gasoline and eleven diesel vehicles were tested on the current European TA procedure NEDC, and on the evolving WLTP. These WLTP tests were then used as base line to estimate for each vehicle a WLTP best case and a WLTP worst case scenario, in line with the finalized version of the WLTP. In the WLTP worst case scenario (WLTP-H) results showed CO2 emissions and energy demands to be on average 11% and 44% higher than NEDC, respectively. Best case scenario (WLTP-L) has on average 1% higher CO2 emissions and 26% higher energy requirements than the NEDC. These values should be considered on top of the 8% average difference between the JRC NEDC test results and the official type approval values. The higher vehicle inertia and road loads (RLs) along with the higher vehicle speeds, are the key parameters of the new procedure that contribute to the increased CO2 emissions and vehicle energy demand (VED). Results from the present study show that moving from NEDC to WLTP have a stronger impact on diesel than on gasoline vehicles. The highest effect of WLTP introduction is measured for vehicles that comply with EURO 6 emission standard (14% increase in CO2 emissions from NEDC to the simulated worst case WLTP), with also the largest difference between JRC measured NEDC tests and declared type approval values (11% difference).

Design and development of an hybrid light commercial vehicle

Nowadays the powertrain hybridization represents one of the most promising solution for delivery companies to reduce the fuel expenditure and to meet the stringent requirements of low emissions urban zones. In the framework of the collaborative Italian Regional iDea (innovative Diesel engine applications) project, which aims to develop innovative technical solutions for a more sustainable mobility, this paper highlights the fuel economy potential along the NEDC (New European Driving Cycle) and WLTC (Worldwide harmonized Light duty Test Cycle) driving cycles of a Plug-in hybrid powertrain developed for a light duty delivery vehicle, showing possible improvements in terms of CO2 emission reductions of 23% and 11%, respectively. After this preliminary investigation on the hybridization benefits, which has been carried out through numerical simulations, and a brief description of the methodology used to size the hybrid powertrain main components, the article shortly presents the powertrain control strategy and the development process of the first prototype. Finally, the work focuses on the main results which have been achieved by the first vehicle prototype during an experimental campaign carried out on a chassis dynamometer.

Development of the World-wide harmonized Light duty Test Cycle (WLTC) and a possible pathway for its introduction in the European legislation

This paper presents the World-wide harmonized Light duty Test Cycle (WLTC), developed under the Working Party on Pollution and Energy (GRPE) and sponsored by the European Union (with Switzerland) and Japan. India, Korea and USA have also actively contributed. The objective was to design the harmonized driving cycle from “real world” driving data in different regions around the world, combined with suitable weighting factors. To this aim, driving data and traffic statistics of light duty vehicles use were collected and analyzed as basic elements to develop the harmonized cycle. The regional driving data and weighting factors were then combined in order to develop a unified database representing the worldwide light duty vehicle driving behavior. From the unified database, short trips were selected and combined to develop a driving cycle as representative as possible of the unified database. Approximately 765,000km of data were collected, covering a wide range of vehicle categories, road types and driving conditions. The resulting WLTC is an ensemble of three driving cycles adapted to three vehicle categories with different power-to-mass ratio (PMR). It has been designed as a harmonized cycle for the certification of light duty vehicles around the world and, together with the new harmonized test procedures (WLTP), will serve to check the compliance of vehicle pollutant emissions with respect to the applicable emissions limits and to establish the reference vehicle fuel consumption and CO2 performance.

Dynamic matrix control applied to emission control of a diesel engine

In this paper we suggest a hierarchical control scheme, applicable to engine control. The chosen setup facilitates the simultaneous control of emissions and torque. On the top level a standard PID controller is installed, setting the injection quantity in order to reach the demand torque, which is a prerequisite to follow a given load profile. The second level is dedicated to the emission control. We apply dynamic matrix control (DMC), which is a specific form of model predictive control. DMC stands out by a very simple way of modeling the controlled process which is represented by step responses. Constraints on the absolute values and maximum rates of change are applied to the manipulable system inputs to cope with given hardware limitations. Moreover, we incorporate so-called operational constraints, thus constraining the input variables to certain polytopic operating regions. Thereby areas with high HC emissions can be excluded in advance. Furthermore we include the predefined demand torque as input to the DMC. With the known impact of transient torque changes on the emissions, the DMC can act in an optimal way with respect to the given load profile. To cope with the nonlinearities of a combustion engine, we apply a network of several DMCs, scheduled by engine speed and load as well as by the manipulable actuators. We also propose a procedure to reduce the amount of modeling data, by introducing a parameterized formulation of the measured step responses. The proposed control concept is then evaluated on a realistic, physically-based engine model for several representative driving sequences, amongst them the well-known New European Driving Cycle (NEDC) and the highly dynamic Worldwide Harmonized Light Duty Test Cycle (WLTC). The advantages of DMC against a conventional PID control are finally summarized and demonstrated on a typical load step.

Impact of ethanol containing gasoline blends on emissions from a flex-fuel vehicle tested over the Worldwide Harmonized Light duty Test Cycle (WLTC)

Regulated and unregulated emissions from a Euro 5a flex-fuel vehicle tested with nine different hydrous and anhydrous ethanol containing fuel blends at 23 and −7°C over the World harmonized Light-duty vehicle Test Cycle and the New European Driving Cycle, were investigated at the Vehicle Emission Laboratory at the European Commission Joint Research Centre Ispra, Italy. The experimental results showed no differences on the regulated and unregulated emissions when hydrous ethanol blends were used instead of anhydrous ethanol blends. The use of E85 and E75 blends (gasoline containing 85% and 75% of ethanol, respectively) resulted in a reduction of NOx emissions (30–55%) but increased the emissions of carbon monoxide, methane, carbonyls and ethanol compared to E5, E10 and E15 blends (gasoline containing 5%, 10% and 15% of ethanol, respectively). The increase of the acetaldehyde and ethanol emissions (up to 120% and 350% at 23°C and up to 400% and 390% at −7°C, for acetaldehyde and ethanol, respectively) caused a severe increment of the ozone formation potential. Most of the studied pollutants presented similar emission factors during the tests performed with E10 and E15 blends. The emission factors of most unregulated compounds were lower over the NEDC (with ammonia as an exception) than over the WLTC. However, when taking into consideration only the cold start emissions, emission factors over the WLTC were observed to be higher, or similar, to those obtained over the NEDC. Low ambient temperature caused an increase of the emissions of all studied compounds with all tested blends.