Engine Control with OpenECU for a Hybrid Vehicle Application ...

Engine Control with OpenECUfor a Hybrid VehicleApplicationPaul Feetenby, Pi ShurlokLes Smith, MIRA Ltd

IntroductionEarlier last year MIRA unveiled a new hybrid car developmentcalled H4VProject 50:50 funded by the Energy Saving Trust (EST) andMIRAH4V is a series/parallel petrol-electric hybrid with the front axledriven by the engine and the rear axle driven by two electricmotors.The hybrid power train is controlled by a vehicle level controlunit (VCU) communicating via CAN to an ‘open architecture’engine ECUThis presentation focuses on the open architecture feature ofthe engine ECU

H4V Hybrid Car

H4V Schematic Layout

Key ObjectivesTo enable ‘fly by wire’ engine control over CAN link for the H4VVCUTo reduce engine base fuel consumptionTo shift minimum BSFC to a lower speed – high torque regionTo evaluate the potential benefits of an open architecture ECUstrategy development tool chain

What is an Open ArchitectureECU ?The underlying controller strategy on an engine ECU is‘closed’ i.e. exe only. In general, source code strategy isnever released by the OE to a third partyLimited access to calibrate ECU labels is enabled only toselected Tier 1s by the OEFor H4V these limitations were untenableSolution: use an ‘open’ architecture ECU strategy –OpenECU from Pi Shurlok was selectedOpenECU is a commercially supported open-architectureautomotive controller development tool comprising ECUhardware and software toolbox

Project PlanWork scope broadly divided into four parts:Phase 1 – Modelling and analysisPhase 2 – Engine characterisationPhase 3 – Migration to OpenECUPhase 4 – Integration of OpenECU with H4V car

Phase 1 - Modelling & Analysis

GT-Power ModellingModels of the base engine were developed and used forparametric studies on:Cam profileValve timing e.g. EMOP-IMOP optimisationPumping work analysis with and without EGRIgnition advanceInlet system geometry

TorqueEngine Performance PredictionInlet valve phasingEMOP-IMOP optimisation

Phase 2 – EngineCharacterisation

Work ScopeRemove engine and complete EMS from OE vehicle and mounton engine dynamometerDerive base engine mappings for the H4V application

Base Engine Mappings

Phase 3 – Migration to

OpenECUOpen-source engine controllerSimulink strategiesExtensible generic engine control strategySupported by industry standard development tools

Work ScopeConfiguration of OpenECU I/O: e.g. ignition coils, fuel injectors,ETB, sensors etc.Develop interface loomFirst-cut calibrationStrategy extensionsCalibration refinement

OpenECU Installation

Bespoke Strategy DesignTorque request modeAllows VCU to manage load contributionsAchieved over CAN bus requestSpeed request modeAllows speed matching for clutch less transmissionengagementAchieved over CAN bus request

Torque Request ModeTorque request to be issued by the VCU over CAN bus to theOpenECU controllerAn estimation model was implemented capable of predicting theneutral load (i.e. no ancillary loads) brake flywheel torque of theengine to within ± 3NmTorque to be limited to an arbitrary ‘safe state’ using an EMSlabel calibrationTorque request requires an electronic throttle body (ETB)Throttle plate motor current to be driven by a PWM output fromthe OpenECU

Torque Estimation Model

Torque Response TestDynamometer based – set speed in torque/speed controlFully-warmed engineDemand torque requested over CANDelivered torque measured on engine dynamometerAgreement within tolerance

Torque Response

Torque Limit ControlStrategy inhibits fuel enrichmentat high loadsOptimal BSFC maintainedEngine and catalyst durabilityTorque limit control featuregiven authority to limit load toprotect engine and catalystEngine effectively de-rated,deficit made-up by EV mode

Speed Request ModeVCU target engine speed requestSpeed matching for clutch less gear changeSpeed elevation for alternator power

Plot – speed matching

BSFC Optimisation

Phase 4 – Integration with H4VVehicle

Torque Request In-Vehicle

SummaryPerformance targets successfully metToolchain and expertise now readily deployable on otherapplicationswww.openecu.comwww.mira.co.uk