Week-4 Challenge WOT Condition Part-2
Q1. Ans: Powertrain block-set provides two types of combustion engine model: mapped and dynamic.
Mapped engine:
1. Mapped engines represent macro engine behaviour as a set of lookup tables 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 and transmission powertrain matching analysis for fuel economy, emissions and performance trade-offs.
Dynamic engine:
1. Dynamic engine decompose engine behaviour into individual component models that account for engine dynamics, most notably intake airflow and turbo charger dynamics.
2. Dynamics engine models are suitable for designing control, estimator and diagnostic, algorithms that depend on dynamic subsystem state.
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.
Q2. 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 pf gas. Figure out an mpge rating is a little more complicated . Since engines that can use an alternative source of fuel cant be measured by liquid gallons of fuel, the mpge rating is calculated by figuring out the number of miles a vehicle can go using the same energy content as gallon of gas. The epa calculated that 33.7kwh of electricity is equivalent to one gallon of gas.
We should go inside ev reference block that is performance calculations:
inside this block will get actual mpg calculations:
Here, three different inputs are taken into considerations:
1. Vehicles speed.
2. Fuel Flow.
3. Battery Power.
The vehicle speed input is in m/s which is converted into miles by multiplying with 0.00062131.
Similarly the kilogram of fuel is converted into cubic meter by multiplying by 1/(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 gallon equivalent by again dividing it with33.7 (since 33.7 kwh = 1 gallon), then divide the value by 3600 to get in per seconds and multiply by .00378541 into get the value in cubic meter per gallons.
Q3. Ans:
Here we have changed drive cycle to wot with a sample time 40 seconds.
We have also altered environment block and changed wind speed to 25m/s & grade to 10.
Environment block:
Results:
Conclusion:
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 deacceleration of the vehicle.
Plot 5: Battery soc:
The Battery soc will falls from 80 to 65% during acceleration of vehicle and it increases slightly to 65 to 70% during de acceleration due to regenerative braking.
Plot 6: Fuel economy:
Maximum fuel economy achieved = 4.675
Q4. Ans:
Simulated results of hev:
Simulated results of ev:
Conclusion :
1. The top speed is achieved by hybrid electric vehicle is more than that od EV.
2. The battery current capacity of pure EV is much higher compared to that of HEV since in EV battery is the only driving unit.
3. Higher fuel economy is achieved in case of pure EV.