Wide Open Throttle Condition 2

Introduction: Power train blockset

Powertrain Blockset provides fully assembled reference application models of automotive powertrains, including gasoline, diesel, hybrid, and electric systems. It includes a component library for simulating engine subsystems, transmission assemblies, traction motors, battery packs, and controller models. Powertrain Blockset also includes a dynamometer model for virtual testing. MDF file support provides a standards-based interface to calibration tools for data import.

Powertrain Blockset provides a standard model architecture that can be reused throughout the development process. You can use it for design tradeoff analysis and component sizing, control parameter optimization, and hardware-in-the-loop testing. You can customize models by parameterizing components in a reference application with your own data or by replacing a subsystem with your own model

1.What is the difference between mapped and dynamic model of engine, motor and generator? How can you change model type?

Ans:

Mapped model: below model gives the image of the mapped model

1.Model uses a set of steady-state lookup tables to characterize engine performance.

1. the model takes the engine or motor speed and torque inputs and generates the required output torque based on the lookup table , without considering the realtime condition.
2. The output values generated are stored for the corresponding input values.

4.It takes very less time for the simulation, and the results are not accurate either

Dynamic model: The dynamic model is represented in the below image

1. Model decomposes the engine behavior into engine characteristics that are separated into lower-level components. By combining components in this way, the models capture the dynamic effects.

2.This model not only takes the inputs but also takes feed back from the generated output, so that the demanded power are achieved. Thus the model generates output as demanded considering the realtime conditions as well.

3.The model is implemented when there is a need of detailed dynamic and component level data is required.

The model takes very longer time to simulation, and its result accuracy is high as well.

To change the model type , goto required

passenger vehicle → Electricplant→ MotGenEvMapped

Right click on the MotgenEvmapped(default) go to variant manager select override variant and select MotGenEvdynamic. which will convert the mapped model to dynamic model.

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

Miles per gallon. Miles per gallon (MPG) is a fuel economy rating determined by how far a car can travel on a gallon of gasoline or diesel.

In case of electric vehicles, the amount of distance travelled by the engine powered car in a gallon of fuel and compared with the electric energy required by the electric vehicle to travel the same distance.

In the visualization block, there is a block called performance calculation block which takes vehcle speed and battery power as input and gives US MPGe and L/100km as output.

Inside this block lies the calculation , where the input vehicle speed is integrated with time to get the distance in meters.

To convert this meters to miles, it is multiplied by 0.000621371( 1m = 0.000621371 miles).

The fuel flow is integrated with tie as well to get the mass flow rate in kg

Then that kg unit is converted to cubic meters by multiplying by 1/(1000*0.739)

This cubic meter is again converted into gallons by multiplying 264.172 factor

The distance in miles and fuel flow in gallons is divided to get the miles per gallon.

Battery power:

The power in wat is converted to kw by dividing 1000

The kw is then converted to kwh/US gallon equivalent by dividing the kw by33.7 which is again divided by 3600 to get the value per second

Multiplying 0.00378541 gives the volume of fuel gallon in cubic meters per second

Then multiplying the value by 739 gives the mass flow rate in kg/s.

And this is added to the fuel flow.

1. Run the HEV Reference Application with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.

The simulation is first run without grade and wind velocity meaning zero grade angle and zero wind velocity.

All the parameters are kept default. The resultant plots are as follows

From the velocity trace we can see that the requested and achieved acceleration has difference due to the forces acting in the vehicles

The total simulation time is 100sec

The top speed of this cycle is 110mph

From the plot 2 the engine speed is 13720rpm

Motor top speed is about 5550rpm

Generator top speed is about 5550rpm

From plot3 the engine torque is about 150Nm

Motor torque is 200Nm

Generator torque has gone negative -30Nm

From plot4

Battery current initial went 500amps and later at constant speed the current decreased to zero and even to negative . this is due to fluctuation in speed and torque of the drive train fluctuating in the constant speed .

Frim plot5

The battery state of charge has decreased from 80% to 66% . when the deceleration starts the battery gets charged due to regenerative braking.

From plot6

MPGe has increased initially due to both motor and engine working at the reduction oof battery for certain level engine took over all the vehicle demand the MPGe has reduced.

The simulation again ran by adding the grade value 10degrees and wind velocity at 10m/s

The resultant plots are as below

From the plot1

The requested and achieved power has huge variation due to increase in thee force of the vehicle , as we increase the grade angle the grade force increases and in addition wind velocity is added , hence the top speed in this case is 60mph

From plot2

In this case the speed of engine is around5000rpm

The speed of the electric motor is around 7500rpm

The speed of the generator is around 13000 rpm

From plot3

The engine torque is about 150Nm

The motor torque initially has risen to 200Nm and at the top speed it has been reduced to70Nm

The generator torque has gone negative that is -30Nm

From plot 4

The battery current is positive that is the battery is discharging during the acceleration period, during the deceleration the battery current is negative that means the battery is charging

Maximum positive current is 160amps

Maximum negative current is 150amps for a short amount of time.

From plot5

The battery state of chargehas reduced from 60 to 20 percentage during the acceleration, during the deceleration the battery is being charged and the battery state of charge has risen to 20to 34 percentage.

From plot6

The miles per gallons efficiency has increased because both engine and electric motor share the demanded power of the vehicle.

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

Lets run the simulation of Hybrid electric vehicle and pure electric vehicle and compare the results.

Hybrid Electric vehicles:

A vehicle that has two or more energy sources and energy converters is called a hybrid vehicle.

The provision of extra energy source is to increase the efficiency of the vehicle.

The simulation results of the HEV application in default parameters

Electric vehicle: Electric vehicles use an electric motor for traction, and chemical batteries, fuel cells, ultra capacitors, and/or flywheels for their corresponding energy sources. The electric vehicle has many vantages over the conventional internal combustion engine vehicle, such as an absence of emissions, high efficiency, independence from petroleum, and quiet and smooth operation.

The simulation results for the pure electric vehicle application is

Result comparision of HEV and Pure EV simulation.

1. From the above resultant plot observation we can say that the velocity plot s almost similar, the acceleration time taken by both electric vehicle and hybrid electric vehicle is also same.
2. The speed of the engine in HEV case is around 5000 and the motor has 13000rpm, whereas in the EV case the motor has the speed of 11000 rpm.
3. The torque obtained by both the HRV and EV has the same similar torque 130-150Nm.
4. The battery current in HEV is risen to 160amps during the acceleration and and surge to the negative 130 amps during the deceleration time.
5. The battery state of charge in HEV case has decreased from 60 to 28 percentage, where as in EV case the battery percentage is 100 to 96.5, which is only 3.5% consumption. By this we can conclude that the electric vehicle is far more efficient than the Hybrid electric vehicle.
6. The fuel economy MPGe for HEV is 16 MPG during the acceleration and reduce slightly during the deceleration as the motor turns off and generator starts charging the battery, where as in the EV case the MPGe equivalent has the 40MPG efficiency , so the Electric vehicle is more efficient than the Hybrid Electric Vehicle.