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Porsche Engineeringdriving technologies

Electrification of the powertrain.Further potentials for downsizing?V. Bevilacqua, E. Jacobs, G. Grauli, J. Wüst

European GT-SUITE Conference, Frankfurt/Main, 21 October 2013

21.10.2013- 3 -

Electrification of the powertrain – further potentials for downsizing?V. Bevilacqua, E. Jacobs, G. Grauli, J. Wüst


> Introduction

> Simulation procedure

> Concepts

> Simulation results

> Determination of power and energy demands

> Conclusions

Electrification of the powertrain – further potentials for downsizing?Contents

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> Significant reduction of CO2 emissions for next generation vehicles.

> Vehicle performance limits the downsizing level.> Demand for a 48 V system and electrical

hybridization.> Electrification of the powertrain is a new degree

of freedom.

Optimization potential of synergic effects?

Introduction

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Potential of fuel consumption reduction

“Ideal Conditions”:ü Power inputû No inertiasû No additional weights

“Inertia Contribution”:ü Power inputü Polar inertiasû No additional weights

Preliminary design of the e-Machines

Battery sizing and total weights assumptions

“Real Conditions”:ü Power inputü Polar inertiasü Overall weights

Evaluation of Power and Energy

demands


demands


demands

Simulation Procedure> 3 levels of approximation for the investigation of hybrid concepts:

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> Reference is a twin charged engine:

− Supercharger + turbocharger (SC+TC)

Other models are hybrid concepts with two different levels of hybridization.

> 3 thermodynamic hybridizations feasible with a system of 48 V:

− E-supercharger + turbocharger (eSC+TC)

− E-flowcharger + turbocharger (eFC+TC)

− E-turbocharger (eTC)

> 1 plug-in hybrid with a system of 280 V:

− turbocharger + e-cranktrain (TC+eCT);

Concepts

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Concepts – Reference SC+TC: Mechanical charger and turbocharger

> Turbo- and super-charged engine.

> SC works up to 3000 rpm (clutch).

> Bypass-valve for the SC.

> Additional CAC.

T

SC

1 CAC

2 CAC

C

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Concepts – Thermodynamic hybridizationeSC+TC: Electrically driven supercharger and turbocharger

T

SC

1 CAC

2 CAC

e-M

C

> Supercharger driven by an e-machine (no clutch).

> Boost pressure controlled by the e-Motor.

> E-Motor: 48 V SPM with external rotor.

− Peak power 8.0 kW

− Max. speed 7500 rpm

> Batteries: 13 lithium-polymer cells.

− Capacity 1.9 kWh

− Weight 11.7 kg

> +27 kg heavier than base model.

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Concepts – Thermodynamic hybridizationeFC+TC: Electrically driven radial compressor (flow charger) and turbocharger

* A DC/DC converter is needed

T

1 CAC

2 CAC

e-MFC

C

> Radial compressor driven by an e-machine.

> Boost pressure controlled by the e-Motor.

> E-Motor: 200 V* SPM.

− Peak power 9.0 kW;

− Max. speed 121 500 rpm;


− Capacity 1.9 kWh;

− Weight 11.7 kg;


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Concepts – Thermodynamic hybridizationeTC: Turbocharger assisted by electrical motor/generator mounted on turboshaft

Te-M

CAC

C

> Single stage turbocharger assisted by an e-machine.

> Only 1 CAC needed.

> Turbocharger is very close to surge limit.

> E-Motor: 200 V* SPM.


− Max. speed 160 000 rpm



− Weight 11.7 kg

> +20 kg heavier than base model. * A DC/DC converter is needed

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Concepts – Plug-in hybridTC+eCT: Turbocharger plus an electrical motor/generator

TC

CAC

e-M/G

> Single stage turbocharger.

> Only 1 CAC needed for this configuration.

> Regenerative braking possible.

> E-Motor: 280 V SPM with concentrated windings.




− Weight 68.4 kg


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> Each engine is coupled with a model of a compact car.

> Four different acceleration maneuver have been analyzed:

− T1: from 60 to 100 km/h in 6th gear




> Simulation constrains for every concept:

− Consistent maximum torque

− Similar time per maneuver (if possible)

− Constant knock tendency (Knock Index)

− Maximum T3 of 950°C

Simulation Procedure

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Simulation Results

Enhanced torque build-up to compensate for the weight

disadvantage.

Maneuver T3 – Real Condition - 80 120 km/hr in 6th gear

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Simulation ResultsManeuver T3 – Real Condition - 80 120 km/hr in 6th gear

SC auxiliary torque

Turbolag compensation by e-cranktrain

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= ~ 6.5 – 7.5

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Determination of power and energy demandsProcedure

> Three main assumption are made for the electric energy recovering:

− Total electric recharge: energy is recovered by regenerative braking and / or charging.

− Partial electric recharge: energy is partially recovered while braking /charging, and partially by the internal combustion engine shifting the load operating point. *

− ICE recharge: energy demand is recovered by the combustion engine. **

* the energy demand is transformed in an equivalent of fuel with an overall efficiency of 30%

** transformation efficiency of 10%

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Partial electric recharge(η = 30 %)

Total electric recharge ICE recharge (η = 10 %)

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***

***200/hr reached 0.7 seconds after the other models









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Conclusions

> Different level of hybridization have been evaluated:− Thermodynamic hybridization with a system of 48 V.

> Fuel consumption improvement up to 6 % with comparable transient behavior.

> Systems show a similar power demand.

− E-turbo: better packaging but limitations due to compressor surge and revolutions of the electrical machine

− E-flow charger: challenge to design a high revolution electrical machine (>150.000 rpm)

− Plug-in hybrid with a system of 280 V.> Improved thermodynamic engine efficiency during transient maneuvers.

> Significant higher vehicle weight.

> Fuel consumption reduction during transient maneuvers are heavily dependent on operating strategy (high degree of freedom) .

> Design of the powertrain is heavily dependent on the driving profile à “Diversification”− Full hybridization shows advantages in urban driving conditions.− Degree of electrification should be lower for driving profiles with long distances and constant speed.

> Hybridization of the powertrain leads to new requirements for the downsizing concepts. Higher total efficiencies are possible, but optimization needs to consider the driving profiles.


Thank you for your attention!

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Later enrichment due to turbolag

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