rapid assessment of electric supercharger system...

Alessandro Renna

Daniel Baumann, IT

AVL Powertrain UK Ltd.

Confidential

RAPID ASSESSMENT OF ELECTRIC SUPERCHARGER

SYSTEM LAYOUTS FOR ENGINE DOWNSIZING

Electronics & Controls Department

28th/29th October 2015

National Motorcycle Museum, Solihull

Alessandro Renna | | 26 October 2015 | 2 Confidential

AGENDA

1. Engine downsizing

2. Simulink MVEM

3. Steady – State validation

4. EDS effect i. Steady – State

ii. Transient Response

iii. Vehicle Response

5. Conclusions


ENGINE DOWNSIZING

• Engine downsizing to reduce fuel consumption and CO2 emissions

• Superchargers and turbochargers can recover BMEP reduction

• Turbochargers have slow transient response (turbo lag) and compressor surge limits air mass filling and torque at low speeds

• Electric driven superchargers (EDS) can provide good boosting particularly at low engine speeds without taking power from the engine (mechanical supercharger solution)


SIMULINK MVEM


SIMULINK MVEM: CYLINDERS


SIMULINK MVEM: RESTRICTION


SIMULINK MVEM: ADIABATIC PIPE

Rm

pVT

WWdt

dm

HHVc

R

dt

dp

p

21

21


SIMULINK MVEM: CHARGING ELEMENTS


SIMULINK MVEM: SHAFT, AIR COOLER

)( ambininout TTeffTT dt

dJbTQTQ outin


SIMULINK MVEM: CONTROLLERS


STEADY – STATE VALIDATION (ONLY TURBOCHARGER)

• Based on real WOT performance for a 1.0L engine with one turbocharger and one after-cooler.

• Reference pressure for waste-gate controller has been set equal to experimental values.


EDS LAYOUTS

Based on validated TC model (only turbocharger), several combinations of turbocharger, electric supercharger and additional inter-cooler have been investigated.


STEADY – STATE: COMPARISON

• Full load simulations with predefined PR set-points.

1

1

PRTWcP inp


STEADY – STATE: COMPARISON + IC

• Full load simulations with additional inter-cooler and the same predefined PR set-points.

1

1

PRTWcP inp


STEADY – STATE: COMPARISON

IC

IC IC

IC

refin

refin

corrpp

TTWW

/

/


TRANSIENT RESPONSE

Transient response at fixed engine speed of ETC, TEC, ECTC and TCEC versus only TC model has been simulated using 2 step signals:

• Throttle tip-in to 100%;

• Electric motor torque for EDS from 0 to 1 Nm;

• Motor is disconnected for EDS PR set-points equal to 1.

EDS and turbocharger inertias are set equal to 5E-05 kg*m2.


TRANSIENT RESPONSE: COMPARISON


TRANSIENT RESPONSE: COMPARISON W/ IC


VEHICLE RESPONSE

dt

dvMFFFF v

vgraderollairt

sin

cos

2

1 2

gMR

gMCR

vACR

vgrade

vrroll

vfrontaldairair

iTQR

F

ivR

n

eng

w

fric

t

veng

2

60

ηfric i Rw Mv Afrontal ρair Cd Cr ϑ

0.8 4 0.3 [m] 1200 [kg] 2 [m2] 1.2 [kg/m3] 0.4 0.015 0 [deg]


VEHICLE RESPONSE: COMPARISON


VEHICLE RESPONSE: COMPARISON + IC


CONCLUSIONS - 1

Steady – State simulations showed:

• EDS can completely recovers the WOT torque deficit at low speeds and its position is not relevant to reach the nominal engine torque

• EDS in 2nd stage can extend the range of use from 1700 rpm to 3200 rpm but with increase of electric power request

• EDS wheel in TEC is more stressed at higher temperatures, so it needs better thermal characteristics and hence more expensive

IC

IC

IC


CONCLUSIONS - 2

Transient simulations showed:

• Transient reduction of turbo lag during acceleration

• ETC and TEC models have basically the same trend

• Vehicle dynamic during tip-in manoeuvre improved without any significant influence of the EDS position

IC

IC

IC


CONCLUSIONS - 3

Use of additional air cooler between the compressors showed:

• Extra increase of WOT torque with the same boost conditions

• Reduction of second stage temperatures

• No improvement of acceleration lag; it just moves operating points of the first stage compressor far from surge.

• Weight, volume and costs of the engine increase

IC

IC

IC

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rapid assessment of electric supercharger system...

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