Week-4 Challenge WOT Condition Part-2

Difference between mapped and dynamic model Engine , Generator and motor :-

Mapped model :- Powertrain blockset provide two types of combustion engine model mapped and dynamic.

Mapped engine represent macro engine behaviour as set of look up tables (brake torque , fuel flow, air mass flow , exhaust temperature , efficiency , emission) as function of commanded load and measured engine speed.

It is very speed and takes less time for the simulation. it also the example for the steady state vehicle model. It is based on the level of detail present in it.

Dynamic model :-

Dynamic engine decompose engine behaviour into individual component (Various subsystems) model that account for engine dynamics.it will take many time to run simulation and result came out is very accurate and realistic in nature.

It is an example of quasi and dynamic state vehicle models. Dynamic engine model are suitable for designing control ,estimator, dignostic algorithm that depend upon dynamic subsystem state.

How to change the model type :- 

Step :- 

•     Go to the power train blockset module in MATLAB after that select any reference vehicle . Suppose we select the electric vehicle reference application blockset. Its block diagram is shown follows:-

  

• Now double click on passenger car block and inside that block their is an electric plant block. Click on that block to view contents inside.

• The above image are the content inside the plant. In these motor block as you can see the model set as motor gen ev mapped model . In order to change into the dynamic model just click on it with right clickon the block and select the variant label model active choice. Now you can see  two option choose the MotgenEv Dynamic.

• In these manner you cam change the model type.

2) How does model calculate miles per gallon ?

    Miles per gallon (MPG) :- 

                    Miles per gallon, is the distance, measured in miles, that a car can travel per gallon of fuel. MPG is also the primary measurement of a car's fuel efficiency. The higher a car's MPG, the more fuel efficient it. Mpg stands for miles per gallon and is used to show how far your car is able to travel for every gallon of fuel it uses. (1 gallon = 4.5 litres approx)

                In power train blockset the fuel economy is calculate as follows :- open the any vehicle model but we open the electric vehicle model and we have to seen the calculation block.

Here the fuel is battery power because the energy supply from battery to vehicle.The model consider the vehicle speed which is drive cycle input here and the battery power of the vehicle to calculate the fuel economy.

Vehicle speed :-

        In the vehicle speed, we can see in above image conversion of speed.When we integrate speed with time we get the distance. The distance is fed to two block first that covered from 0 to 100 Km as weel as miles. After that the ouput of these miles and distance block fed to L/100 and USMPG block. In US, the MPG is calculate for miles 1m = 0.000621miles 

         We are measuring the amount of fuel which is equivalent to battery power in case of electric vehicle. the fuel required to travel the for 100 Km and also the distance covered for USMPG then result are compared.

Battery power :- 

          The initial battery power is in watt and it is divide by 1000 and convert into KW. after that the power convert into energy by multiplying with time. Then we convert energy into energy in US gallons by diding with 33.7. then divide the output  of US EPA KWh by 3600 to convert KWh to KW. then we have to convert it to volume of fuel flow.The flow unit is m^3/gallon and it multiplied by a factor 0.00378541 with energy value. This fuel is further integrated to convert it into m^3.It is multipliedby 1000 to convert it into litres. This is fed to L/100 Kms block.

            Then it is also converted into equivalent US gallon by multipliyng M^3 unit to 262.12 this is fed to USMPG block.Then integrate distance measure is converted into miles and fed to USMPPG block.It is again converted 100Kms and fed to the L/100Kms block.this result are then comparison. Finally distance measure and energy calculate and they divideto get result in miles /gallon.

3) Run the HEV reference applicationwith WOT drive cycle and change the grade value :-

               The HEV uses both ICE(Internal combustion) engine and battery power to move the vehicle. The power train sequence of HEV is  shown in following figure.

           

    Now open the HEV reference application using matalb documentation. the block diagram is shown below.

In these block, we give the input drive cycle to model is WOT drive cycle as per given condition. the specification is follows:-

                                     

Specification :-  Start time :- 1s ,  Initial speed :- 1 mph , Final speed :- 50 mph 

                        Time to start deceleration :- 50s , WOT simulation time :- 100s

Now we have to change the grade value and the wind velocity that why we need to open enviroment block and change the grade value and wind velocity.

         

we have applied the 5 degree of grade angle and wind velocity iis 8 m/s.Now we can run the performance test and view the result.

 

Result :- 

• First graph is the target velocity graph, In these graph we want maximum speed is near about 115 mph but due to grade angle and wind velocity the speed achieve is about 75 mph.
• The acceleration time from intital to maximum speed was approxiately clos to 50s and the decelaration time max to min to be about 5 sec.
• The second graph show the speed of motor, engine, generator. From plot rpm is greater while the vehicle is accelerating and lower when decelerating.
• Fifthe graph shows the SOC. The SOC is depleted when vehicle accelerate and SOC increase during the vehicle decelerate.
• Overall we see the result, the fuel economy higher when battery driven the vehicle and decrease when IC engine start to drive the vehicle.  

4) Compare the hybrid and pure electric vehicle :-

Pure EV uses a battery propulsion system to run vehicle .The powertrain setup of pure electric vehicle is follows :- 

We have already discuss the HEV performance, now we will look performance of pure EV with same input parameter:- 

 

           While setting up all enviroment condition are same such as wind velocity and grade angle and also the WOT drive cycle are same. Run the system see the result.

result :- 

           As compare with HEV model result, We conclude that, the fuel economy continously increase.So we conclude that pure EV is better than HEV beacuse lesser SOC decline , better fuel economy ,Zero emission.