Week-4 Challenge WOT Condition Part-2

Question 1)

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

Sol:

Mapped Model:

• Mapped Model usses a set of Steady state Look up table for simulation and it's operation.
• If the lookup table is present then the simulation becomes easier and it gives results based on the data interpreted. This is also called Global Based Model.
• The drawback is more data has to be collected and we need to make some assumptions.
• The effect on the engine can be simulated with the array of data interpreted in the system.
• The motor specifications such as RPM,Voltage,Power, efficiency,tempertaure,etc are to be entered for simulation.
• Specifications for torque,current,etc and other parameters to be entered for simulation

Dynamic Model:

• Dynamic model decomposes the engine behaviour into engine characteristics that are seperated into lower level blocks. Combining these blocks together to form a dynamic model.
• It operates dynamically depending on the situation of operation detailed data and specifications are not required and the simulation gives the detailed analysis of the components simulated. This is called Real time Based Model.
• It cannot be simulated using custom preferences.
• The engine perfomance will be simulated based on the original specifications of that engine and the results are real time.
• The actual details would be same as the results obtained.
• All the details and specifications would be considered as per the actual and dynamic state of the same would be obtained then.

Open the hybrid matlab powertrain file as seen below :

Open Passenger Car block. Sub blocks seen below :

Open Electric Plant block and sub blocks as seen below :

Open Generator block and sub blocks as seen below :

Right click and select following options to change the model :

>>Variant

>>Label Mode Active Choice

>>GenDynamic(GeDynamic)

Question 2)

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

Solution :

Factors affecting the fuel efficiency are listed below

1) Vehicle Speed

2) Battery Power

3) Fuel Flow

The vehicle speed inputs is in m/s which is converted into miles by multiplying with 0.000621371.

similarly the kilogram of fuel is converted into cubic meter by multiplying by1/(1000*0.739)

this cubic meter value is then converted into gallons by multiplying it with 264.172.the mile value and gallon value is used to find mpg of the vehicle.

now the battery value is initially converted from watts to kwh by dividing with 1000 and then to gallon equivalent by again dividing it with 33.7(sincw 33.7 kwh=1 gallon)

then divide the value by 3600 to get in per seconds and multiply by 0.00378541nto get the value in cubic meter per gallons.

Question 3)

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

Solution:

With Wot :

Click on run. Set the time for 100 seconds

Results:

RESULTS:

Current goes to 175 and then decreases

Peak RPM is about 12000

MAKING CHANGES TO WIND VELOCITY AND GRADE

Velocity and grade is found in enviroment block.

Set Grade =5; Wind velocity =10;

Output :

The battery current increased slightly.

Rest is similiar to previous graph

SOC decreases

Question 4)

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

Solution :

HEV:

simulated results of HEV:

Pure EV:

simulated results of pure EV:

Conclusion:

• The top speed is achieved by hybrid electric vehicle is more than that of EV.
• The battery current capacity of pure EV is much higher compared to that of HEV since in EV battery is the only driving unit.
• Higher fuel economy is achieved in case of pure EV.