Hybrid Passenger Car Emissions - CLEERS

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Hybrid Passenger

Car Emissions A concept study by means of

simulation

CLEERS | 17-19/09/2019 Thomas Glatz

Christoph Pötsch

Johann C. Wurzenberger

TG, CP, JCW | | 15 September 2019 | 2Public

Legislation

▪ Real Driving Emissions, in-use tests

▪ CO2 / fuel efficiency

Hybrid Electric Vehicles

▪ Beneficial for fuel economy

▪ Challenging for exhaust gas aftertreatment (light-out during e-drive phase)

Vehicle Thermal Management Measures

▪ Passive:Component positioning, sizing and isolation

▪ Active: Engine load shifts, burners and E-heaters, etc.

The variety of design variants combined with control strategies under arbitrary driving conditions needs model based development approaches

Model Requirements

▪ Physical models are needed for early concept investigations

▪ Models at vehicle level need to reflect changes on driving conditions and control

▪ Real-time capable models are needed to

▪ Support efficiently “mass simulations”

▪ Support model re-use on virtual testbeds

MOTIVATION


Motivation

Model

▪ Global Overview

▪ Modeling Domains

▪ Selected Components

Results

▪ Simulation Variants

▪ Operating Strategy

▪ Emissions

▪ Computational Performance

Conclusions

OUTLINE


Multi-Disciplinary System Simulation

▪ Thermodynamics

▪ Electric

▪ Driveline

▪ Cooling

▪ MAC/WHR

▪ Info Flow

Multi-Rate Co-Simulation

▪ Dedicated solves for each physical domain

▪ Energy conserving balancing over domain borders

Scalable Physical Modeling

▪ Component library (ready to go)

▪ Import interfaces (ready to customize)

SYSTEM MODEL (01/13)OVERVIEW – TOOL


MODELING DOMAIN

▪ Drivetrain

▪ Electric Motor

▪ Combustion Engine

▪ Hybrid Control

▪ Cycle Run

SYSTEM MODEL (02/13)OVERVIEW – MODEL


DRIVETRAIN COMPONENTS

▪ Vehicle

▪ Cockpit

▪ Gearbox

▪ Hybrid clutch

▪ Wheels

▪ Brakes

▪ Final drive

▪ Differential

SYSTEM MODEL (03/13)DRIVETRAIN


MODEL AND SPECIFICATION

▪ Passenger car

▪ 1850 kg nominal curb weight

▪ 2750 mm wheelbase

▪ Road resistances and dynamic wheel loads calculated based on dimensions and load state

▪ Wheel loads calculated considering vehicle motion

▪ The model parameterization mainly touches rolling an air resistance

SYSTEM MODEL (04/13)DRIVETRAIN/VEHICLE



▪ Combines two clutch components

▪ Connect combustion engine, electric motor and gearbox

▪ Controlled by the Hybrid control

▪ Functions for smooth opening and closing

▪ Open and closing clutches changes the DOFs in the model

SYSTEM MODEL (05/13)DRIVETRAIN/HYBRID CLUTCH


E-MOTOR COMPONENTS

▪ Electric machine

▪ Hybrid battery and starter battery

▪ DC/DC converter

▪ Electric consumer (→ connects to e-

heater)

SYSTEM MODEL (06/13)E-MOTOR



▪ Permanent magnet synchronous machine

▪ Motor and generator functionality

▪ 150 Nm at 48 V

▪ Map based approach i.e. power losses are modeled empirically

▪ Torque controlled

SYSTEM MODEL (07/13)E-MOTOR/ELECTRIC MACHINE



▪ 48 V hybrid battery with 2 rows of 13 cells (~ 48 V), 1250 Wh (~ Prius)

▪ 12 V starter battery

▪ Equivalent electrical circuit model

▪ Predict voltage response to a current at a specific SoC

▪ Batteries are parameterized (R/C values) based on experimental charge/discharge measurements

SYSTEM MODEL (08/13)E-MOTOR/HYBRID & STARTER BATTERY


COMBUSTION ENGINE COMPONENTS

▪ Gas Path

▪ Cylinder

▪ EAS

SYSTEM MODEL (09/13)COMBUSTION ENGINE



▪ 2.3liter 4 cylinder gasoline

▪ Environment and air filter

▪ Compressor and turbine

▪ Charged air cooler

▪ Throttle

▪ Intake manifold

▪ Cylinder block and combustion

▪ Exhaust aftertreatment

▪ Simple engine controls

▪ Components are parameterized based on testbed data from engine and components

SYSTEM MODEL (10/13)COMBUSTION ENGINE/GAS PATH



▪ Air charge, thermodynamic conditions and emissions based on:

▪ Main cylinder geometry, injection equipment and thermal boundary conditions

▪ Network of sub-models: trapped air, SOC, MFB50, CD, PFP, temperatures and emission formation, exhaust gas enthalpy, wall heat losses, torque

▪ Complex parts of combustion described by empirical models derived from a pool of measurements

▪ Model is parameterized based on testbed data

SYSTEM MODEL (11/13)COMBUSTION ENGINE/CYLINDER



▪ Three Way Catalyst1.5l, 400CPSI/4mil, 94g/ft3 Pt, 7g/ft3 Rh

▪ Transient 1-D model

▪ Oxidation of H2, HCs and CO by NOx or O2, O2 storage, and oxidation of H2, HCs and CO by stored O2

▪ Rates are defined via open reaction coding interface

▪ Parameterization is done semi-automatized using generic optimization methods

SYSTEM MODEL (12/13)COMBUSTION ENGINE/EAS



▪ Controls combustion engine, electric motor, brakes and clutches

▪ Main Inputs: acceleration and brake pedal signals, velocity, speed, SoC

▪ Maps and C-code

▪ 7 Main Operating Modes:

1. Combustion engine driven only

2. Hybrid driven

3. Electric motor driven only

4. Recuperation

5. Forced Engine Brake

6. Charging

7. Start Combustion Engine

8. Braking

9. Stop combustion Engine

SYSTEM MODEL (13/13)HYBRID CONTROL


Motivation

Model

▪ Global Overview



Results



▪ Emissions


Conclusions

OUTLINE


INVESTIGATE IMPACT OF

▪ Passive measures

1) Catalyst positioning and sizing

2) Aftertreatment insulation

▪ Active measures

3) In-Cylinder post-injection

4) Electrically heated catalysts

1) Moves the catalyst from underfloor to close coupled position (reduced length / removed heat loss of piping in front of catalyst)

2) Increase of catalyst insulation from 5mm to 20mm

3) Raises cylinder exhaust temperatures

4) Electric heating up to 500W in case catalyst temperature is critically low and SoC is sufficient

▪ All cases started with SoC 66% and cold-start of combustion engine at 25°C

▪ Compared to the base case

THERMO MANAGEMENT (01/10)VARIATION MATRIX


THERMO MANAGEMENT (02/10)TEST CYCLE

▪ Cycle is randomly assembled, featuring a dedicated stand-still phase

▪ Very minor differences between the cases, possible explanation: due to control strategies

▪ All four case performed the same drive cycle


THERMO MANAGEMENT (03/10)OPERATING STRATEGY – INSTANTANEOUS

▪ Case (4) Electrically heated catalyst: Runs more often in CE_DRIVE and CHARGING as the E-heating pulls energy from the battery

▪ The operating strategy is simple and configured for this concept study.

0... CE_DRIVE (IC Engine only)1... HYBRID_DRIVE2... EV_DRIVE (E Motor only)3... RECUP (recuperation charges battery)4... RECUP_EB (IC Engine supported Braking, “Downhill mode”), 5... CHARGING (IC Engine charges battery)6... CE_START (E Motor starts the IC Engine)7... BRAKE (strong braking, both engines decoupled)8... Stop Engine (stops the IC engine)


THERMO MANAGEMENT (04/10)OPERATING STRATEGY – ACCUMULATED

▪ Case (4) Electrically heated catalyst: Runs about 3% less e-drive, 4% more IC drive and 3% less stop

Closed coupled position

Underfloor insulated

In-cylinderpost-injection

E-heated catalyst


THERMO MANAGEMENT (05/10)OPERATING CONDITIONS – ENGINE/EAS

▪ Engine:

▪ Small differences of engine speed

▪ E-heating shows longer engine operation

▪ EAS:

▪ Insulation & CC positioning raise mean temps

▪ Post injection shows little impact

▪ E-heating can be overserved during stand-still phase


THERMO MANAGEMENT (06/10)ENGINE & TAILPIPE EMISSIONS – CO

Engin

e o

utlet

Tailpip

e

▪ Insulation and CC positioning

▪ do not influence engine out emissions

▪ Significantly influence tailpipe emissions

▪ Post injection shows little impact on engine out and tailpipe emissions

▪ E-Heating shows deteriorated engine emissions that are partially compensated by the EAS


THERMO MANAGEMENT (07/10)ENGINE & TAILPIPE EMISSIONS – NOX

▪ CC positioning and E-heating shows slight increase of engine out NOX (different EAS engine operating points)

▪ Tailpipe values show very poor NOX conversion IC Engine control

(lambda=1). No sweeps (O2 loading, purging). With a better or real life IC Engine ECU would look better.

Engin

e o

utlet

Tailpip

e


THERMO MANAGEMENT (08/10)ENERGY BALANCE – FUEL AND SOC

▪ CC positioning and E-heating shows slight increase of fuel consumption

▪ SOC is pretty similar for all cases (caused by SOC control)


THERMO MANAGEMENT (09/10)ENGINE & TAILPIPE EMISSIONS – SUMMARY

▪ E-Heater shows reduced CO reduction for the price of higher fuel consumption!(This statement must be assessed considering the simple controls used in this study)


SUMMARY

▪ Thermodynamics, Drivetrain:1 ms, explicit fixed step solver

▪ Aftertreatment: 100 ms, implicit fixed step

▪ Electrics: 1 ms, implicit fixed step

▪ Simulation results recording with 1 Hz

▪ Real-time factor of ~0.7 on Windows 10 64bit Office Notebook, with Intel®Core™ i5-835oU CPU @ 1.70 GHz 1.9 GHz and with 16 GB of RAM

THERMO MANAGEMENT (10/10)COMPUTATIONAL PERFORMANCE


Motivation

Model

▪ Global Overview



Results



▪ Emissions


Conclusions

OUTLINE


▪ Modeling

▪ The parameterization of the individual components is straight foreword for most of the components

▪ Cylinder uses a dedicated wizard

▪ TWC is semi-automated

▪ Tooling

▪ Model runs in real-time

▪ Engineering

▪ The results show no benefit of E-heater. This is attributed to the applied simple controls

▪ Real XCUs can be used on virtual testbeds to exclude this dependency

CONCLUSIONS

AVL VIRTUAL TESTBED™

Ecu drawer

Loads drawer

Real time models

Documents

Hybrid Passenger Car Emissions - CLEERS