1. WLTP Correlation engine modeling
BMW,
WLTP Correlation engine modeling
Comparison of different approaches for engine modeling

2. WLTP correlation engine modeling overview metamodel JRC and TUG
JRC MetaModel
includes two modules
Module 1: Power-RPM-Module
calculates the input signals (engine power, engine speed) to run module 2
considers input from - cycles (speed- , gear-profile, …)
- road load
- drivetrain
mech. and electr. consumers
temperature characteristic
start/stop-system
Module 2: fuel consumption Module
calculates the fuel consumption of a vehicle using the:
6/7 parameter consumption map (fitting tool)
input from module 1
TUG MetaModel
based on "veline"-approach
procedure (overview)
WLTP measurement
calculation of the WLTP veline
considers start/stop system
considers hot/cold start effect
conversion of the WLTP veline into the NEDC veline
∆CO2 = kn · ∆rpm (kn needs to be defined)
calculation of the NEDC fuel consumption
WLTP Correlation Engine Modeling, BMW,

3. WLTP correlation engine modeling Diesel engine vehicle
±2g/km
0.4g/km
6.6g/km
13.1g/km
6.5g/km
All consumption values from measurement and simulation are determined with warm engine to neglect the influence of the JRC temperature model (“work in progress”).
It can not be ensured, that the meta model was handled appropriate.
The consumption map fitting tool leads to inappropriate matching (like earlier investigations have shown).
The calculation tool for engine load and engine speed (“JRC MetaModel”) increases the deviation additionally.
WLTP Correlation Engine Modeling, BMW,

4. WLTP correlation engine modeling Feedback metamodel JRC and TUG
Principle of TUG model works very well (BMW internal model uses same principle and is very accurate).
"k-faktor" not known and the principle of a linear relationship does not work from our perspective.
Possible improvement: Use a bunch of simulations (sensitivity of engine speed / transmission ratios) and develop an empirical formula (BMW metamodel approach).
JRC:
Fitting of the fuel consumption map obviously introduces an error.
Accuracy of "module 1" not satisfactory and unclear influence of cold start (not included now).
Possible improvement: Fitting of fuel consumption map only in a very limited area.
Possible improvement: More detailed modeling of the vehicle, e.g. constant efficiency of drivetrain not realistic (it is more like offset + relative efficiency).
WLTP Correlation Engine Modeling, BMW,