Energy Model

2015-05-20

Rudolf Brziak

Background

Generic trend towards simulation tools usage in automotive industry today

Reduced hardware needs

Increased repeatability

Improved traceability

Cost reduction

Specific need for tools within the Energy & Propulsion area

Simple – easy to use for non-experts

Flexible – should include subsystems of most conventional and hybrid driveline topologies

Accessible – clear, functional and open for expert users to modify according to specific needs

Scope

Fuel Economy / CO2 Emissions and Performance

Simulation of complete vehicle

Flexible physical model with efficiency maps

Simple Excel user interface for batch runs

Data structure for parameters and data sets

SIL/MIL/HIL - plant model for controls validation

Separate sub-models for controls and hardware

RealTime capable

Structural Overview

ENGINE CLUTCH TRANS WHEEL CAR

ENGINE TRANS

DRIVER

BATTERYMG1 MG2 MG3 MG4

WHEEL

MG1 MG2 MG4MG3 BMU

HYBRIDcontrolPedal

Force GearTorque

T=i’

F=ma

F=ma

T=i’

T=i’

T=i’

U=RI U=RI

Hybrid Mode

Limits Limits

CONV.VEHICLE

ELECTRICVEHICLE

Functional Overview

CONTROLS

• Stop/Start

• Regeneration

• Boost

• EV-mode

• Series mode

ELECTRIC MOTORS

• Max/Min Torque

• Efficiency

BATTERY

• Capacity

• Impedance

• Voltage

• Max/Min P,I,V

DRIVER

• Performance tests

• Fuel economy cycles

• Generic driving profiles

COMBUSTION ENGINE

• Max/Min Torque

• Efficiency

Clutch

• Friction force

• Hydraulic converter

TRANSMISSION

• Gear Ratios

• Efficiency

• Time & Speed shifting

Simulink Overview

Analysis Example - Efficiency

Walk-down from baseline vehicle to market target

0

20

40

60

80

100

120

140

Target CO2

8

Project Example - Elforest

SCOPE: Series hybrid forestry machine

Compilation of component data

1 combustion engine, 2 generators, 8 drive motors, battery, etc

Definition of driving cycle and loads

Speed, height profile, timber load, rolling resistance, crane load, etc.

Compilation of measured data

Fuel rate, engine speed, battery current, etc.

Adaption of simulation model to the driveline, usage and loads of the

forestry machine

Parameter study

Suggestions for improvement

of machine productivity

Development Process Example

Energy model supports analysis loops with increasing levels of detail

1. Concept selection – minimum level of detail

2. Hardware definition – higher level of hardware details

minimum calibration details

3. Calibration targets – high level of detail

9

User Interface and Data Structure Simple and intuitive Excel

interface (fig. left)

Efficiency maps and other data sets located by pointers in file structure (fig. below)

MATLAB script executes Simulink model and processes results

Performance and Validation

800 850 900 950 1000 1050 1100 1150

0

0.5

1

1.5

2

t (s)

Fuel flow

(g/s

)

Ref

EM

800 850 900 950 1000 1050 1100 1150 1200

0

50

100

150

200

t (s)

Engin

e b

rake t

orq

ue (

Nm

)

Ref

EM

Average runtimes on i5 laptop

(NEDC 1180sec, single core)

Conventional MT 14sec

ISG, stop/start 14sec

P3, e-cruise 15sec

Size on disc

Model, script <1 MB

Docs, libs <5 MB

0 200 400 600 800 1000 1200-20

0

20

40

60

80

100

120

140

t (s)

Vehic

le S

peed (

km

/h)

Ref

EM

EM Cycle speed trace

Conclusions and Future Work

Energy Model Capabilities

Significantly reduced analysis time for simulations of a wide range of vehicle and powertrain variants

Verification of vehicle drivability metrics, using and developing sub-system calibration baselines

Validation of controls algorithms as the plant model in a Model-In-the-Loop test setup

Next steps

Extending libraries of existing sub-systems - engines, transmissions, batteries, motors, etc…

Adding and/or updating models of next generation of fuel saving technologies

Further refinement of post-processing scripts and visualization tools

Q&A

Thank you for your attention!