Week-4 Challenge WOT Condition Part-2

Wot condition 2

Aim:

1. What is the difference between mapped and dynamic model of engine, motor and generator? How can you change model type?
2. How does the model calculate miles per gallon? Which factors are considered to model fuel flow?
3. Run the HEV Reference Application with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.
4. Keeping all other parameters same, compare the simulated results of hybrid and pure electric powertrains.

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

Ans:

Power train block set provides two types of combustion engine models: mapped and dynamic

Mapped engine:

1. Mapped engines represent macro engine behavior as a set of look up tables (brake torque fuel flow , air mas flow , exhaust ,temperature, efficiency and emission as functions of commanded load and measured engine speed
2. Mapped engine models are suitable for analysis and design activities that do not require engine subsystem dynamic characteristics for example in engine transmission powertrain matching analysis for fuel economy emission and performance trade-offs

Dynamic engine:

1. Dynamic engine decomposes engine behavior into individual component models that account for engine dynamics most notably in take air flow and turbo charger dynamics
2. Dynamics engine models are suitable for design control estimator and diagnostic algorithims that depend on dynamic subsystem states for example in closed loop AFR (air fuel ratio) control algorithm development

We can switch between mapped and dynamic engines by following below procedures:

1. Open the EV model in Simulink
2. Enter the passenger car block by double clicking it
3. Then go to electric plant block
4. Inside the motor block right click to find the variant option

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

Ans:

Miles per gallon (mpg) &miles per gallon equipment (mpge):

For a conventional gasoline vehicle the fuel efficiency is calculated via miles per gallon (mpg) however fuel efficiency for hybrid electric vehicles is calculate via miles per gallon equipment (pge) mpg is the number of miles your car can drive per gallon of gas figuring out the number of miles a vehicle can go using the same energy content as gallon of gas the epa calculate that 33.7 kilowatt hours of electricity is equivalent to one gallon gas

We should go inside EV reference block that is performance calculation:

Inside this block will get actual mpg calculation:

Here three different inputs are taken into consideration:

1. vehicle speed
2. fuel flow
3. battery power

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 by 1/(1000*0.739)

this cubic number 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(since 33.7 KWH =1gallon)

3) Run the HEV Reference Application with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.

here we have change drive cycle to WOT with a sample time 40seconds

We have also altered environment block and changed wind speed to 25m/s &grade to 10

Environment block: