Week-4 Challenge WOT Condition Part-2

Q1) What is the difference between mapped and dynamic model of engine, motor and generator? How can you change model type?

Sol: Mapped Model : It is based on the look up tables and not on actual components. Simulation takes less time due to simpler operation.

Dynamic Model: It is based on actual component model.Each component is modeled separately and simulation takes more time.

Eg: Mapped Motor

Dynamic model of Generator:

Double click on the above we will get the below fig.

MAPPED MODEL OF SI ENGINE:

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:

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, T_cmd, brake torque, T_brake, and engine speed, N. If you select Input engine temperature, the tables are also a function of engine temperature, Temp_Eng.

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Q2) .How does the model calculate miles per gallon? Which factors are considered to model fuel flow?

Answer: Simulink block to calculate Miles/Gallon.

• Double click on the block 'Performance calculations'.
• Vehicle speed data is used to calculate the distance traveled in meters which is then converted to miles (marked as 'a')
• Battery power data is used to find power used in kWh which is then converted to gasoline-equivalent using US EPA value by dividing with 33.7 (marked with yellow)
• As per the US environmental protection agency(EPA) 1 gallon of gasoline is equal to 33.7 kWh
• Dividing distance traveled in miles by the number of gallons, we can get miles per gallon.(marked as 'b')
• For HEV this gallon(gasoline-equivalent of battery power) is added with gallon used by IC engine then miles per gallon is calculated.

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Q3:Run the HEV ReferenceApplication with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.

Answer:

> Open the HEV reference application

_{STep2: Click on the Drive cycle source and change the parameters as per our requirement as marked in yellow.}

_{Next Click on the Envuronment block as below:}

_{Case 1: Grade - 0, Wind velocity 0 m/s}

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_{Case 2: Grade - 5, Wind velocity 10 m/s}

_Results:

RESULTS:

with the increase in grade and wind velocity,

• Peak velocity achieved is reduced as gradient force and aerodynamic force becomes dominant.
• Fuel economy is also reduced because the distance traveled is reduced due to external forces as seen in image 2 bottom corner.
• Battery SOC at the end of WOT acceleration is similar but during deceleration battery is charged more is the grade and wind velocity is less.

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Q4. Keeping all other parameters same, compare the simulated results of hybrid and pure electric powertrains.

Solution:

The Pure electric vehicle model is shown in fig(a).

The drive cycle settings can be altered as per requirement as shown in fig(b).

Fig(a)

fig(b)

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Results:

• The Vehicle couldn’t achieve the Target velocity. It attained only 40mile per hour in 20sec.
• Battery State of Charge decreased from 80% to 78.5%.
• Battery supplied its maximum current of 220A
• To Improve WOT performance, Motor has to deliver more torque and Battery should support fast discharging.--------------
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