Week-4 Challenge WOT Condition Part-2
1.What is the difference between mapped and dynamic model of engine, motor and generator? How can you change model type?
In the powertrain block set we can select the model of internal combustion engine,electric motor and generator as mapped or dynamic type.
Mapped model:
1.The mapped model is the one in which the data points are designed in the look-up table.
2. The Engine/Motor torque requirement is sensed and the Motor/Engine block generates the required torque output just as required simply without considering the real time motor or engine parameter.
3. The output values are stored for the corresponding input value of engine motor and generator.
4. The accuracy of this type is not very high, but the simulation will be done in very less time as it is not run on real time parameters.
Dynamic Model:
1. The Dynamic model in other hand uses the combination of outputs from various subsystems to generate output.
2.It runs on real time simulation, where the required input is taken from the drive cycle for that individual real time simulation gets performed and summing all the results of subsystem gives the output for the simulation.
3. As per the drive cycle requirements the initial bus voltage,current is given along with the vehicles feedback so that it runs the actual simulation at that particular moment through the drive cycle.
4. The accuracy of this model is very high as it considers the real output from all the subsystem to generate the output.
5. The simulation will take very long time to complete as it has so many individual simulations running by all the subsystem of the engine,motor/generator.
Steps to select model type:
1. In powertrain blockset module we first need to select the vehicle type first whether it is full electric or hybrid vehicle.
2. After that the simulink model appears with the work flow block of model.
3. Passanger block----> Electric plant--->EV Motor Generator block.
2. How does the model calculate miles per gallon? Which factors are considered to model fuel flow?
Miles per gallon:
1.Miles per gallon is nothing but the fuel economic rate determined how far the car can travel on a gallon of petrol or Diesel for a Engine powered car.
2. In case of an Electric vehicle it tells us the energy which is equivalent that of a engine powered car to propel the car through a distance.
3. The amount of fuel energy required to move an Engine powered car through a distance is determined and then it is compared to the eqivalent amount of electric energy required to move the car through the same distance and is expressed as Miles per gallon.
4. The Powertrain blockset has a model that calculates Miles per gallon for all Kid of vehicles.
The model described above takes the input parameters such as Vehicle speed, Fuel Flow and Battery Power to calculate the Fuel consumption, equivalent battery consumption and calculates the Miles per gallon.
Vehicle speed & Fuel Flow:
1.The vehicle speed is an important factor while considering the Fuel Consumption at that particular time.So to determine the fuel consumption throughout the drive cycle.
2. To convert speed to distance we can integrate with time, similarly we can integrate velocity with time to get the distance covered.
3. The Fuel flow is expressed as the mass flow rate which is nothing but the amount of fuel at each moment in kg/sec.Now by integrating it the result will be in mass of fuel and by converting into volume (1/(1000*0.739)), if we need to convert to lit multiply by 1000.
Battery:
1. Incase of battery the energy from the battery required to propel the vehicle equivalent to that of engine is calculated.
Where the battery power is given in watts, which can be converted into kw by dividing with 1000.
2.Power into energy by multiplying with time into kwh
where the energy from Kwh to equivalent energy in US gallon of automobile by dividing with 337.
3. The final battery energy equation in kg/sec is given as a input from fuel flow parameters in order to find the equivalent us gallon energy and estimate the miles per gallon.
Miles per gallon calculation:
1. The inputs from vehicle speed ---> distance (miles)
2. Inputs from fuel flow nothing but (Battery energy + Fuel energy)---->in US Gallons (*264.17)
3.Two Input, miles converted & Equivalent US Gallon is further divided & result in Miles/Gallon.
3. Run the HEV Reference Application with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.
Open the HEV reference model from powertrain into simulation setup and change the drive cycle from FTP-75 to WOT and run the default WOT condition without changing the parameters and then run it by changing the grade and wind values accordingly.
This HEV model which consist of Drive cycle which determines how the vehicle will move and how the battery responds with the load requirement and having the environment block to configurate the inputs such as grade, wind velocity,pressure and temp.
Input values in block parameters:Drive cycle of WOT follows:
Output after running the WOT drive cycle follows:
And now proceed for changing the input parameters such as grade and wind velocity from environment block and run the WOT cycle to compare the changes in outputs.
Output result follows relating the changes in the Enginespeed,motorspeedngenspd(rpm) and Engtrq,Mottrq,Gentrq(Nm) while comparing.
4.Keeping all other parameters same, compare the simulated results of hybrid and pure electric powertrains.
Simulation of hybrid electric vehicle powertrain :
Simulation of pure electric vehicle with same parameter as of HEV :
Comparison:
Sl.no HEV EV
1. Battery (soc) 62 75.5
2. Battery Current Below -200 Above -200
3. US Fuel Economy (MPGe) Around 9 31 and maintains above 40 throughout