Mapped SI Engine

Spark-ignition engine model using lookup tables

  • Library:
  • Powertrain Blockset / Propulsion / Combustion Engines

    Vehicle Dynamics Blockset / Powertrain / Propulsion

Description

The Mapped SI Engine block implements a mapped spark-ignition (SI) engine model using power, air mass flow, fuel flow, exhaust temperature, efficiency, and emission performance lookup tables. You can use the block for:

  • Hardware-in-the-loop (HIL) engine control design

  • Vehicle-level fuel economy and performance simulations

The block enables you to specify lookup tables for these engine characteristics. The lookup tables, developed with the Model-Based Calibration Toolbox™, are functions of commanded torque, Tcmd, brake torque, Tbrake, and engine speed, N. If you select Input engine temperature, the tables are also a function of engine temperature, TempEng.

TableInput Engine Temperature Parameter Setting
offon

Power

ƒ(Tcmd,N)ƒ(Tcmd,N,TempEng)

Air

ƒ(Tbrake,N)ƒ(Tbrake,N,TempEng)

Fuel

Temperature

Efficiency

HC

CO

NOx

CO2

PM

To bound the Mapped SI Engine block output, the block does not extrapolate the lookup table data.

Virtual Calibration

If you have Model-Based Calibration Toolbox, click Calibrate Maps to virtually calibrate the 2D lookup tables using measured data. The dialog box steps through these tasks.

Task

Description

Import firing data

Import this firing data from a file. For more information, see Using Data (Model-Based Calibration Toolbox).

Required Data

Optional Data

  • Engine speed, rpm

  • Engine torque, N·m

  • Air mass flow rate, kg/s

  • Brake specific fuel consumption, g/(kW·h)

  • CO2 mass flow rate, kg/s

  • CO mass flow rate, kg/s

  • Exhaust temperature, K

  • Fuel mass flow rate, kg/s

  • HC mass flow rate, kg/s

  • NOx mass flow rate, kg/s

  • Particulate matter mass flow rate, kg/s

Collect firing data at steady-state operating conditions when injectors deliver the fuel. Data should cover the engine speed and torque operating range. Model-Based Calibration Toolbox uses the firing data boundary as the maximum torque.

To filter or edit the data, select Edit in Application. The Model-Based Calibration Toolbox Data Editor opens.

Import non-firing data

Import this non-firing data from a file.

  • Engine speed, rpm

  • Engine torque, N·m

Collect non-firing (motoring) data at steady-state operating conditions when fuel is cut off. All non-firing torque points must be less than zero. Non-firing data is a function of engine speed only.

Generate response models

For both firing and non-firing data, the Model-Based Calibration Toolbox uses test plans to fit data to Gaussian process models (GPMs).

To assess or adjust the response model fit, select Edit in Application. The Model-Based Calibration Toolbox Model Browser opens. For more information, see Model Assessment (Model-Based Calibration Toolbox).

Generate calibration

Model-Based Calibration Toolbox calibrates the firing and non-firing response models and generates calibrated tables.

To assess or adjust the calibration, select Edit in Application. The Model-Based Calibration Toolbox CAGE Browser opens. For more information, see Calibration Tables (Model-Based Calibration Toolbox).

Update block parameters

Update the block lookup table and breakpoint parameters with the calibration.

Cylinder Air Mass

The block calculates the normalized cylinder air mass using these equations.

MNom=PstdVdNcylRairTstdL=(60smin)Cpsm˙air(1000gKg)NcylNMNom

The equations use these variables.

L

Normalized cylinder air mass

MNom

Nominal engine cylinder air mass at standard temperature and pressure, piston at bottom dead center (BDC) maximum volume, in kg

Cps

Crankshaft revolutions per power stroke, rev/stroke

PstdStandard pressure
TstdStandard temperature
Rair

Ideal gas constant for air and burned gas mixture

Vd

Displaced volume

Ncyl

Number of engine cylinders

N

Engine speed

m˙intk

Engine air mass flow, in g/s

Turbocharger Lag

To model turbocharger lag, select Include turbocharger lag effect. During throttle control, the time constant models the manifold filling and emptying dynamics. When the torque request requires a turbocharger boost, the block uses a larger time constant to represent the turbocharger lag. The block uses these equations.

Dynamic torque

dTbrakedt=1τeng(TstdyTbrake)

Boost time constant

τbst={τbst,rising       when Tstdy>Tbrakeτbst,falling      when TstdyTbrake

Final time constant

τeng={τthr       when Tbrake<fbst(N)τbst       when Tbrakefbst(N)

The equations use these variables.

Tbrake

Brake torque

TstdySteady-state target torque
τbst

Boost time constant

τbst,rising, τbst,falling

Boost rising and falling time constant, respectively

τeng

Final time constant

τthrTime constant during throttle control
ƒbst(N)Boost torque speed line
NEngine speed

Fuel Flow

To calculate the fuel economy for high-fidelity models, the block uses the volumetric fuel flow.

Qfuel=m˙fuel(1000kgm3)Sgfuel

The equation uses these variables.

m˙fuelFuel mass flow
Sgfuel

Specific gravity of fuel

Qfuel

Volumetric fuel flow

Power Accounting

For the power accounting, the block implements these equations.

Bus Signal DescriptionEquations

PwrInfo

PwrTrnsfrd — Power transferred between blocks

  • Positive signals indicate flow into block

  • Negative signals indicate flow out of block

PwrCrkshft

Crankshaft power

τengω

PwrNotTrnsfrd — Power crossing the block boundary, but not transferred

  • Positive signals indicate an input

  • Negative signals indicate a loss

PwrFuel

Fuel input power

m˙fuelLHV

PwrLoss

Power loss

τengωm˙fuelLHV

PwrStored — Stored energy rate of change

  • Positive signals indicate an increase

  • Negative signals indicate a decrease

Not used

The equations use these variables.

LHV

Fuel lower heating value

ω

Engine speed, rad/s

m˙fuelFuel mass flow

τeng

Fuel mass per injection time constant

Ports

Input

expand all

Torque, Tcmd, in N·m.

Engine speed, N, in rpm.

Engine temperature, TempEng, in K.

Dependencies

To create this port, select Input engine temperature.

Output

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Bus signal containing these block calculations.

SignalDescriptionUnits

IntkGassMassFlw

Engine air mass flow output

kg/s

NrmlzdAirChrg

Normalized engine cylinder air mass

N/A

Afr

Air-fuel ratio (AFR)

N/A

FuelMassFlw

Engine fuel flow output

kg/s

FuelVolFlw

Volumetric fuel flow

m3/s

ExhManGasTemp

Engine exhaust gas temperature

K

EngTrq

Engine torque output

N·m

EngSpd

Engine speed

rpm

CrkAng

Engine crankshaft absolute angle

0(360)CpsEngSpd18030dθ

where Cps is crankshaft revolutions per power stroke.

degrees crank angle

Bsfc

Engine brake-specific fuel consumption (BSFC)

g/kWh

EoHC

Engine out hydrocarbon emission mass flow

kg/s

EoCO

Engine out carbon monoxide emission mass flow rate

kg/s

EoNOx

Engine out nitric oxide and nitrogen dioxide emissions mass flow

kg/s

EoCO2

Engine out carbon dioxide emission mass flow

kg/s

EoPM

Engine out particulate matter emission mass flow

kg/s

PwrInfoPwrTrnsfrdPwrCrkshft

Crankshaft power

W
PwrNotTrnsfrdPwrFuel

Fuel input power

W
PwrLoss

Power loss

W
PwrStored

Not used

Engine brake torque, Tbrake, in N·m.

Parameters

expand all

Block Options

To model turbocharger lag, select Include turbocharger lag effect. During throttle control, the time constant models the manifold filling and emptying dynamics. When the torque request requires a turbocharger boost, the block uses a larger time constant to represent the turbocharger lag. The block uses these equations.

Dynamic torque

dTbrakedt=1τeng(TstdyTbrake)

Boost time constant

τbst={τbst,rising       when Tstdy>Tbrakeτbst,falling      when TstdyTbrake

Final time constant

τeng={τthr       when Tbrake<fbst(N)τbst       when Tbrakefbst(N)

The equations use these variables.

Tbrake

Brake torque

TstdySteady-state target torque
τbst

Boost time constant

τbst,rising, τbst,falling

Boost rising and falling time constant, respectively

τeng

Final time constant

τthrTime constant during throttle control
ƒbst(N)Boost torque speed line
NEngine speed

Dependencies

Selecting Include turbocharger lag effect enables these parameters:

  • Boost torque line, f_tbrake_bst

  • Time constant below boost line, tau_thr

  • Rising torque boost time constant, tau_bst_rising

  • Falling torque boost time constant, tau_bst_falling

Select this to create the EngTemp input port.

The block enables you to specify lookup tables for these engine characteristics. The lookup tables, developed with the Model-Based Calibration Toolbox, are functions of commanded torque, Tcmd, brake torque, Tbrake, and engine speed, N. If you select Input engine temperature, the tables are also a function of engine temperature, TempEng.

TableInput Engine Temperature Parameter Setting
offon

Power

ƒ(Tcmd,N)ƒ(Tcmd,N,TempEng)

Air

ƒ(Tbrake,N)ƒ(Tbrake,N,TempEng)

Fuel

Temperature

Efficiency

HC

CO

NOx

CO2

PM

Configuration

If you have Model-Based Calibration Toolbox, click Calibrate Maps to virtually calibrate the 2D lookup tables using measured data. The dialog box steps through these tasks.

Task

Description

Import firing data

Import this firing data from a file. For more information, see Using Data (Model-Based Calibration Toolbox).

Required Data

Optional Data

  • Engine speed, rpm

  • Engine torque, N·m

  • Air mass flow rate, kg/s

  • Brake specific fuel consumption, g/(kW·h)

  • CO2 mass flow rate, kg/s

  • CO mass flow rate, kg/s

  • Exhaust temperature, K

  • Fuel mass flow rate, kg/s

  • HC mass flow rate, kg/s

  • NOx mass flow rate, kg/s

  • Particulate matter mass flow rate, kg/s

Collect firing data at steady-state operating conditions when injectors deliver the fuel. Data should cover the engine speed and torque operating range. Model-Based Calibration Toolbox uses the firing data boundary as the maximum torque.

To filter or edit the data, select Edit in Application. The Model-Based Calibration Toolbox Data Editor opens.

Import non-firing data

Import this non-firing data from a file.

  • Engine speed, rpm

  • Engine torque, N·m

Collect non-firing (motoring) data at steady-state operating conditions when fuel is cut off. All non-firing torque points must be less than zero. Non-firing data is a function of engine speed only.

Generate response models

For both firing and non-firing data, the Model-Based Calibration Toolbox uses test plans to fit data to Gaussian process models (GPMs).

To assess or adjust the response model fit, select Edit in Application. The Model-Based Calibration Toolbox Model Browser opens. For more information, see Model Assessment (Model-Based Calibration Toolbox).

Generate calibration

Model-Based Calibration Toolbox calibrates the firing and non-firing response models and generates calibrated tables.

To assess or adjust the calibration, select Edit in Application. The Model-Based Calibration Toolbox CAGE Browser opens. For more information, see Calibration Tables (Model-Based Calibration Toolbox).

Update block parameters

Update the block lookup table and breakpoint parameters with the calibration.

Dependencies

To enable this parameter, clear Input engine temperature.

Breakpoints, in N·m.

Breakpoints, in rpm.

Breakpoints, in K.

Dependencies

To enable this parameter, select Input engine temperature.

Number of cylinders.

Crank revolutions per power stroke.

Volume displaced by engine, in m^3.

Fuel lower heating value, LHV, in J/kg.

Specific gravity of fuel, Sgfuel, dimensionless.

Ideal gas constant of air and residual gas entering the engine intake port, in J/(kg*K).

Standard air pressure, in Pa.

Standard air temperature, in K.

Boost torque line, ƒbst(N), in N·m.

Dependencies

To enable this parameter, select Include turbocharger lag effect.

Time constant below boost line, τthr, in s.

Dependencies

To enable this parameter, select Include turbocharger lag effect.

Rising torque boost time constant, τbst,rising, in s.

Dependencies

To enable this parameter, select Include turbocharger lag effect.

Falling torque boost time constant, τbst,falling, in s.

Dependencies

To enable this parameter, select Include turbocharger lag effect.

Power

The engine torque lookup table is a function of commanded engine torque and engine speed, T = ƒ(Tcmd, N), where:

  • T is engine torque, in N·m.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Click to plot table.

Dependencies

To enable this parameter, clear Input engine temperature.

The engine torque lookup table is a function of commanded engine torque, engine speed, and engine temperature, T = ƒ(Tcmd, N, TempEng), where:

  • T is engine torque, in N·m.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

  • TempEng is engine temperature, in K.

Dependencies

To enable this parameter, select Input engine temperature.

Air

The engine air mass flow lookup table is a function of commanded engine torque and engine speed, m˙intk = ƒ(Tcmd, N), where:

  • m˙intk is engine air mass flow, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, clear Input engine temperature.

Click to plot table.

Dependencies

To enable this parameter, clear Input engine temperature.

The engine air mass flow lookup table is a function of commanded engine torque, engine speed, and engine temperature, m˙intk = ƒ(Tcmd, N, TempEng), where:

  • m˙intk is engine air mass flow, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

  • TempEng is engine temperature, in K.

Dependencies

To enable this parameter, select Input engine temperature.

Fuel

The engine fuel mass flow lookup table is a function of commanded engine torque and engine speed, MassFlow = ƒ(Tcmd, N), where:

  • MassFlow is engine fuel mass flow, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, clear Input engine temperature.

Click to plot table.

Dependencies

To enable this parameter, clear Input engine temperature.

The engine fuel mass flow lookup table is a function of commanded engine torque, engine speed, and engine temperature, MassFlow = ƒ(Tcmd, N, TempEng), where:

  • MassFlow is engine fuel mass flow, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

  • TempEng is engine temperature, in K.

Dependencies

To enable this parameter, select Input engine temperature.

Temperature

The engine exhaust temperature lookup table is a function of commanded engine torque and engine speed, Texh = ƒ(Tcmd, N), where:

  • Texh is exhaust temperature, in K.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, clear Input engine temperature.

Click to plot table.

Dependencies

To enable this parameter, clear Input engine temperature.

The engine exhaust temperature lookup table is a function of commanded engine torque, engine speed, and engine temperature, Texh = ƒ(Tcmd, N, TempEng), where:

  • Texh is exhaust temperature, in K.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

  • TempEng is engine temperature, in K.

Dependencies

To enable this parameter, select Input engine temperature.

Efficiency

The brake-specific fuel consumption (BSFC) efficiency is a function of commanded engine torque and engine speed, BSFC = ƒ(Tcmd, N), where:

  • BSFC is BSFC, in g/kWh.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, clear Input engine temperature.

Click to plot table.

Dependencies

To enable this parameter, clear Input engine temperature.

The brake-specific fuel consumption (BSFC) efficiency is a function of commanded engine torque, engine speed, and engine temperature, BSFC = ƒ(Tcmd, N, TempEng), where:

  • BSFC is BSFC, in g/kWh.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

  • TempEng is engine temperature, in K.

Dependencies

To enable this parameter, select Input engine temperature.

HC

The engine-out hydrocarbon emissions are a function of commanded engine torque and engine speed, EO HC = ƒ(Tcmd, N), where:

  • EO HC is engine-out hydrocarbon emissions, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, clear Input engine temperature.

Click to plot table.

Dependencies

To enable this parameter, clear Input engine temperature.

The engine-out hydrocarbon emissions are a function of commanded engine torque, engine speed, and engine temperature, EO HC = ƒ(Tcmd, N, TempEng), where:

  • EO HC is engine-out hydrocarbon emissions, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

  • TempEng is engine temperature, in K.

Dependencies

To enable this parameter, select Input engine temperature.

CO

The engine-out carbon monoxide emissions are a function of commanded engine torque and engine speed, EO CO = ƒ(Tcmd, N), where:

  • EO CO is engine-out carbon monoxide emissions, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, clear Input engine temperature.

Click to plot table.

Dependencies

To enable this parameter, clear Input engine temperature.

The engine-out hydrocarbon emissions are a function of commanded engine torque, engine speed, and engine temperature, EO HC = ƒ(Tcmd, N, TempEng), where:

  • EO HC is engine-out hydrocarbon emissions, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

  • TempEng is engine temperature, in K.

Dependencies

To enable this parameter, select Input engine temperature.

NOx

The engine-out nitric oxide and nitrogen dioxide emissions are a function of commanded engine torque and engine speed, EO NOx = ƒ(Tcmd, N), where:

  • EO NOx is engine-out nitric oxide and nitrogen dioxide emissions, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, clear Input engine temperature.

Click to plot table.

Dependencies

To enable this parameter, clear Input engine temperature.

The engine-out nitric oxide and nitrogen dioxide emissions are a function of commanded engine torque, engine speed, and engine temperature, EO NOx = ƒ(Tcmd, N, TempEng), where:

  • EO NOx is engine-out nitric oxide and nitrogen dioxide emissions, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

  • TempEng is engine temperature, in K.

Dependencies

To enable this parameter, select Input engine temperature.

CO2

The engine-out carbon dioxide emissions are a function of commanded engine torque and engine speed, EO CO2 = ƒ(Tcmd, N), where:

  • EO CO2 is engine-out carbon dioxide emissions, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, clear Input engine temperature.

Click to plot table.

Dependencies

To enable this parameter, clear Input engine temperature.

The engine-out carbon dioxide emissions are a function of commanded engine torque, engine speed, and engine temperature, EO CO2 = ƒ(Tcmd, N, TempEng), where:

  • EO CO2 is engine-out carbon dioxide emissions, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

  • TempEng is engine temperature, in K.

Dependencies

To enable this parameter, select Input engine temperature.

PM

The engine-out particulate matter emissions are a function of commanded engine torque and engine speed, where:

  • EO PM is engine-out PM emissions, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, clear Input engine temperature.

Click to plot table.

Dependencies

To enable this parameter, clear Input engine temperature.

The engine-out particulate matter emissions are a function of commanded engine torque, engine speed, and engine temperature, where:

  • EO PM is engine-out PM emissions, in kg/s.

  • Tcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

  • TempEng is engine temperature, in K.

Dependencies

To enable this parameter, select Input engine temperature.

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