Week-4 Challenge WOT Condition Part-2

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

ANS:

powertrain 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 lookup tables, brake torque, fuel flow, air mass flow, exhaust temperature, efficiency, and emissions as commands load and measured engine speed functions.

2) Mapped engine models are suitable for analysis and design activities that do not require engine subsystem dynamic characteristics, for example in engine and transmission powertrain matching analysis for fuel economy, emissions, and performance trade-offs.

*For the Dynamic engine how do we shift the Mapped engine to the Dynamic engine:

1) open passenger car block.

2) In the passenger car we see an Electric plant.

3) Right-click on the Electric plant various option opened

4) then go to the Variant option and click on Label mode active choice.

5) we see two options mapped engine and Dynamic engine click on the dynamic engine to change the engine as shown in the image.

Dynamic engine:

1) Dynamic engine decomposes engine behavior into individual component models that account for engine dynamics, most notably intake airflow and turbocharger dynamics.

2) Dynamics engine models are suitable for designing control, estimator, and diagnostic, algorithms 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 the below procedures:

1) open the EV model in simulink.

2) enter the passenger car block by double-clicking it.

3) then go to the electric plant block.

4) inside the motor block right click to find the variant option.

Question 2): How does the model calculate miles per gallon? Which factors are considered to model fuel flow?

ANS:

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

for a conventional gasoline vehicle, the fuel efficiency is calculated via miles per gallon (mpg).

However, fuel efficiency for hybrid electric vehicles is calculated via miles per gallon equivalent(pge).mpg is the number of miles your car can drive per gallon of gas. figuring out an mpg rating is a little more complicated. since engines that can use an alternative source of fuel can't be measured by liquid gallons of fuel, the more rating is calculated by figuring out the number of miles a vehicle can go using the same energy content as a gallon of gas. the EPA calculated that 33.7-kilowatt hours of electricity is equivalent to one gallon of gas.

We should go inside ev reference block that is performance calculations:

Inside the performance calculation block, we see mpg calculation values we change values as per what we need:

Three different inputs are taken into consideration:

1. vehicle speed.

2. fuel flow.

3. battery power.

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

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

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

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

then divide the value by 3600 to get in per second and multiply by 0.00378541nto get the value in cubic meters per gallon.

Question 3): Run the HEV ReferenceApplication with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results?

ANS:

we have changed the drive cycle to wot with a sample time of 50 seconds.

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

Environment block: i change Grade value as 10 and wind_x value as 25.

Scope:

plot 1:trace velocity,target,actual:

top velocity achieved =50.1 mph.

time taken to accelerate = 29.034 sec.

time taken to deaccelerate = 2.471 sec.

plot 2: motor&engine rpm:

top motor rpm=5712 rpm.

top engine rpm = 5451 rpm.

plot 3:motor& engine torque:

maximum motor torque = 306.6 N-m.

maximum engine torque = 174.7 N-m.

plot 4:battery current:

the battery supply current is at its maximum value of 167 ampere when full throttle is applied by the user it reduces drastically to the value of negative 150 during deaccelaration of the vehicle.

plot 5:battery soc:

the battery soc will falls from 80 to 65 % during accelaration of vehicle and it increases slightly to 65 to 70 % during de accelaration due to regenerative braking.

plot 6:fuel economy:

maximum fuel economy achieved = 4.675.

Question 4): Keeping all other parameters same, compare the simulated results of hybrid and pure electric powertrains?

ANS:

simulated results of hev:

simulated results of ev:

Conclusion:

1. The top speed achieved by a hybrid electric vehicle is more than that of an EV.

2. The battery current capacity of pure EV is much higher compared to that of HEV since an EV battery is the only driving unit.

3. Higher fuel economy is achieved in the case of pure EVs.