the control methods for an electrified double-clutch ... · •accurate modelling of the hybrid dct...

CEVT is a wholly owned subsidiary of Zhejiang Geely Holding Group

The control methods for an electrified double-clutch transmission

Muddassar Zahid Piracha Energirelaterad Fordonsforskning 2016

1

Muddassar Piracha Industrial PhD student within Electric Propulsion Systems Supervisors Anders Grauers (Signals and Systems at Chalmers) Johan Hellsing (Electric Propulsion Systems at CEVT AB)


Motivation

• Increasingly stringent requirements to reduce CO2 emissions make the electrification of vehicles as a necessary measure for the future

• In 2008, 23% of CO2 was emitted by transport sector

• That’s about 1 ton CO2 per person per year

• Cost is a major hurdle in progress towards electrification

• But now legislation in Europe is being tightened

• 130 g / km by 2015

• 95 g / km by 2021

• 68-78 g / km by 2025

MOTIVATION 2


Project Role

• China has the largest fuel emission per capita in the world according to European Commission and Netherlands Environmental Assessment Agency report released in 2014

• China intends to limit fuel consumption to 5 liters / 100km in 2020

• The developed Hybrid DCT will be an integral part of strategy to reduce emissions on all of Geely Group’s cars

PROJECT ROLE 3


Hybrid DCT

HYBRID DCT LAYOUT 4

• Hybrid DCT fits within traditional platform hence costs less

• Compared to an Electric vehicle, it has a smaller battery and electric powertrain as hence costs less

• It has only one electric motor hence costs less than other PHEV transmission concepts

• Compared to other hybrid DCT concepts, it has 2 clutches hence costs less

• Research will be to eliminate the starter motor and cost will be reduced further


Hybrid DCT functions

HYBRID DCT FUNCTIONS 1 5

Electrical Launch OR Zero emission driving

Hybrid driving

Battery Charging at stand still


Hybrid DCT functions

HYBRID DCT FUNCTIONS 2 6

Charging during drive

Regenerative breaking

Starting Engine


Research Plan

• Develop control strategy for active synchronization of even gears

• Develop control strategy for reduction of driveline vibrations during engine start-stop

• Optimized hybrid control strategy to increase fuel efficiency and reduce CO2 emissions

• Calculate energy flow in battery and consequently the battery life expectancy due to modified hybrid control strategy

• Reduction of the engine load transients, so EMS can reduce emissions, effectively decreasing the dimension and cost of catalytic converter

RESEARCH PLAN 7


Issue of Active synchronization of even gears

• Electric Motor adds a high inertia to input shaft

→Speed synchronization for shifting needs to be actively controlled

• In Hybrid Mode a 2→4 shift is 2→3→4 shift, so a torque interrupt shift is avoided but in Zero emission mode engine is Off

• So in Zero emission mode, the gear shifts are longer and hence degrade the drivability of the vehicle

ISSUE 1 8

Zero emission driving


Solution strategy of Active synchronization of even gears

• The solution strategy to decrease shift time in zero emission vehicle has following steps

• Detailed modeling of complete hybrid power train

• Modeling of electric motor controller

• Verification of models with test data from Chalmers test rig

• Implementation and verification of improvements in electric motor controller

• Consideration that aggressive control strategy may lead to reduction in battery life

• Review of gear synchronizer design w.r.t safe engagement at a high rpm difference

• Consideration that synchronizer teeth geometry is limited by manufacturing technology

SOLUTION STRATEGY 1 9


Issue of driveline vibrations during engine start-stop

• During Zero emission mode, engine is Off and

High Level Control decides to start the engine

• Engine can be started by a separate starter motor if SoC is low

• Clutch 1 or Clutch 2 can be used to provide engine with cranking torque

• Engine is a variable load → vibrations in the driveline

ISSUE 2 10

Starting Engine during zero emission driving


Solution strategy of driveline vibrations during engine start-stop

• The solution strategy to decrease drive line vibration with engine start/stop

• Detailed modeling and vibrational analysis of complete hybrid power train including engine vibrations

• Verification of models with test data from Chalmers test rig

• Implementation and verification of improvements in electric motor controller and clutch torque controller

• Consideration that aggressive control strategy may lead to reduction in battery life

• Consideration that slipping the clutch for extended period of time results in higher temperatures



Research Work at Chalmers University of Technology

Modelling and methodology for evaluation of a powertrain in a parallel hybrid electric vehicle

PhD project at Department of Applied Mechanics, Division of Combustion

Sarp Mamikoglu(PhD student), Dr. Jelena Andric, Assoc. Prof. Petter Dahlander, Prof. Ingemar Denbratt

• Accurate modelling of the hybrid DCT (motor + transmission) and validation with test data

• Engine setup & calibration, measurements and modelling

• Development of complete powertrain model and control strategies for synergy between the ICE, EM and DCT (minimized fuel consumption & emissions, maximized battery life & drivability)

• Revision for the hybrid powertrain model and control strategy optimization

RESEARCH AT CHALMERS 12


Summary

With improved drivability and vibration-free start the Hybrid DCT will not only be a low cost hybrid solution but also a premium one


the control methods for an electrified double-clutch ... · •accurate modelling of the hybrid dct...

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