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?
Mapped Engine : Mapped engine is the default settings in powertrain blockset.It is used to measure the performance parameter of the vehicle by using standard lookup table which are preferd to the system. This type of modelling is less accurate.If any other parameter like input engine temperature is selected then lookup table values are also a function of the temperature parameter. The data extracted from lookup tables are air mass flow, fuel flow, emission data, exhaust temperature and efficiency. This data is used to find out other parameters which are needed by the end user.
Dynamic Engine : This type of model uses real time data fed by the user at run time for modelling. This model is more accurate than mapped engine model. This type of model is used when the data of subsystem of a vehicle is required.we can calculate brake torque fuel flow, port gas mass flow, exhaust temperature, exhaust mass flow rate and exhaust emissions.
Mapped Motor : The mapped motor works in torque control mode. This type of motor is used when the user requires a faster simulation and doesn't have the knowledge of motor parameters. The output torque and reference torque is compared and changes are made. Input torque or speed can be specified, electrical losses and maximum motor power and torque can be defined.
Dynamic motor : In the dynamic motor a three phase interior permanent magnet synchronous motor (PMSM) is used. The block uses three phase input voltages to regulate the individual phase currents, allowing control of the motor torque or speed. This block is used when the user knows what parameters are to be used in that particular simulation. This motor is more accurate.
Mapped Generator : The mapped generator block is also similar like other blocks. Most of the data required is taken from the lookup tables corresponding to the given input parameters. Its simulation time is less.
Dynamic Generator : The dynamic generator involves user entering the parameters manually during the run time for their particular applications. The results take time and are more accurate.
TO change the model from mapped to dynamic
open the EV model in simulin
Enter the passenger car block by double click
Go to eletric plant block
inside the motor block right click to find the variant option
2.How does the model calculate miles per gallon? Which factors are considered to model fuel flow?
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 mpge rating is a littile 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 milles a vehicle can go using the same energy content as gallon of gas.the epa calculated that 33.7 kilowatt hours of electriccity is equivalent to one gallon of gas.
We should go inside EV reference block that is performance calculations
Here, 2 different input are taken into considerations
Vehicle speed
battery power
The vehicle speed inputs is m/s which is converted into miles by multiplying with 0.000621371
Now the battery value is intially converted from watts to kwh by dividing with 1000 and then to gallon equavalent by again didving it with 33.7
3.Run the HEV ReferenceApplication with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.
Change the wind speed and grade from the Environment block.
Battery SOC: The battery SOC keeps on depleting until regenerative braking starts. This increases the SOC.
Trace velocity target and actual graph ; the yellow line indicates the desired path and blue line is the actual path . So it can be seen that battery power is not enough to meet the requirement of the grade and wind velocity.
Battery current Graph when the vehicle is accelerating the battery current is also increasing when the velocity is constant the current requirement also becomes constant
Engine ,motor and generator speed intially only motor is used to start the vehicle as motor has high intial torque. Later generator keeps in changing the battery when SOC drops below 70%.
Engine, motor and generator torque motor torque is high intially and then engine kicks in at a later stage. generator torque is negative as its changingthe battery.
4.Keeping all other parameters same, compare the simulated results of hybrid and pure electric powertrains.
The top speed is achieved by hybrid electric vehicle is more than that of EV.
The battery current capacity of pure EV is much higher compared to that of HEV since in EV battery is the only driving unit.
Higher fuel economy is achieved in case of pure EV.