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?

Power Train block set provides two types of combustion engine Model. One is 'Mapped' and another one is 'Dynamic'

Mapped Engine

• 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 functions of commanded load and measured engine speed.
• 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 tradeoffs.

Dynamic Engine

• Dynamic engines decompose engine behavior into individual component models that account for engine dynamics, most notably intake airflow and turbocharger dynamics.
• Dynamic engine models are suitable for designing control, estimator, and diagnostic algorithms that depend on dynamic subsystem states, for example, in closed-loop AFR control algorithm development.

Model type can be changed by following command

Steps:

Open EvReference Application

And then Right click on 'Motor Block' <Variant< Active label mode< select Mappped/ Dynamic

It will change the blockset inside the 'Motor block'

Question 2

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

Miles per gallon (mpg) - Conventional Vehicle

Miles per gallon equivalent (mpge):- Hybrid Electric Vehicle

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(mpge).

mpg is the number of miles your car can drive per gallon of gas. Figuring out an mpge 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 mpge rating is calculated by figuring out the number of miles a vehicle can go using the same energy content as gallon of gas.

Here, The epa calculated that 33.7 kilowatt hours of electricity is equivalent to one gallon of gas.

For intrepretation, we should go inside Visualization block

Then, going inside Performance calculation

Here factors considered for input are

• Vehicle Speed
• Fuel flow
• Battery Power

The vehicle speed input 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)

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=1 gallon)

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

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.

Question 3

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

Hev blockset

Wot Condition

Drive cycle is changed to WOT- wide open throttle and the sample time is set for 40 seconds

Grade and wind speed is also changed in the environment block as 15 and 25m/s

Performance Scope:

Result

plot 1:trace velocity,target,actual:

top velocity achieved =60 mph.

time taken to accelerate = 13.636 sec.

time taken to decelerate = 4.04sec.

plot 2: motor & engine rpm:

top motor rpm=17014 rpm.

top engine rpm = 5744 rpm.

plot 3:motor & engine torque:

maximum motor torque =178.6 N-m.

maximum engine torque = 174.7 N-m.

plot 4:battery current:

The battery supply current is at its maximum value of 183 ampere when full throttle is applied by the user it reduces drastically to the value of negative 131 during deceleration of the vehicle.

plot 5:battery soc:

The battery soc will fall from 60 to 59.4% during acceleration of the vehicle and it increases slightly to 59% to 61% during the acceleration due to regenerative braking.

plot 6:fuel economy:

maximum fuel economy achieved = 13.3

Question 4

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

Comparing it with EV reference Application

Ev Blockset

Perfomance Scope with same parameters:

Conclusion:

By comparing the HEV and EV perfomances in the Scope

• The top Speed of Hybrid electric vechicle is more than pure Electric Vehicle.
• The battery capacity of the pure EV is higher than the HEV since its battery is the only driving unit.
• Higher fuel efficinency is achieved by pure EV.