Abstract
The combination of different propulsion and energy storage systems for hybrid vehicles is changing the focus in the field of powertrain calibration. Shorter time-to-market as well as stricter legal requirements regarding the validation of Real Driving Emissions (RDE) require the adaptation of current procedures and the implementation of new technologies in the powertrain development process. In order to achieve highest efficiencies and lowest pollutant emissions at the same time, the layout and calibration of the control strategies for the powertrain and the exhaust gas aftertreatment system must be precisely matched. An optimal operating strategy must take into account possible trade-offs in fuel consumption and emission levels, both under highly dynamic engine operation and under extended environmental operating conditions. To achieve this with a high degree of statistical certainty, the combination of advanced methods and the use of virtual test benches offers significant potential. An approach for such a combination is presented in this paper. Together with a Hardware-in-the-Loop (HiL) test bench, the novel methodology enables a targeted calibration process, specifically designed to address calibration challenges of hybridized powertrains. Virtual tests executed on a HiL test bench are used to efficiently generate data characterizing the behavior of the system under various conditions with a statistically based evaluation identifying white spots in measurement data, used for calibration and emission validation. In addition, critical sequences are identified in terms of emission intensity, fuel consumption or component conditions. Dedicated test scenarios are generated and applied on the HiL test bench, which take into account the state of the system and are adjusted depending on it. The example of one emission calibration use case is used to illustrate the benefits of using a HiL platform, which achieves approximately 20% reduction in calibration time by only showing differences of less than 2% for fuel consumption and emission levels compared to real vehicle tests.
Highlights
The contribution of direct and indirect vehicle emissions to air pollution and increasing greenhouse gases (GHG) in the atmosphere has led to increasingly stringent emission standards being imposed by legislators worldwide
This paper presents the conception for a novel methodology that aims to provide a calibration procedure for robust system layout of conventional and hybrid powertrains with focus on GHG and pollutant emission reduction
With the best NOX –CO trade-off achieved with Calibration 3 and the cases of highest NOX (Calibration 1) and highest CO (Calibration 5) emissions, a comparison is performed on the chassis dynamometer to evaluate the ability to reflect the real-world behavior of the adjustments to the engine control unit (ECU) used on the HiL test bench
Summary
The contribution of direct and indirect vehicle emissions to air pollution and increasing greenhouse gases (GHG) in the atmosphere has led to increasingly stringent emission standards being imposed by legislators worldwide. With the potential of increasing the system efficiency and reducing the fuel consumption [9], one of the most common approaches for GHG reduction of passenger vehicles is the hybridization of the powertrains. This paper presents the conception for a novel methodology that aims to provide a calibration procedure for robust system layout of conventional and hybrid powertrains with focus on GHG and pollutant emission reduction. After pointing out explicit challenges and backgrounds of the emission calibration process with focus on RDE specifications, current methodologies for RDE validation and virtual calibration are presented. An outlook towards the use of virtual test benches using the presented concept for optimization and validation of emissions and operating strategies of hybrid powertrains is given
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