Week-4 Challenge WOT Condition Part-2

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

Solution:

Mapped model:

• In the mapped model, the data points are pre-assigned in the lookup tables.
• These models just represent the real-time machines but not work completely as the real-time machines, they may be changes in their working.
• The engine or motor torque required is sensed and the motor or engine block generates the output just as required simply without considering any real-time motor or engine parameters.
• The accuracy of this type is not that high, but the simulation run at less time without considering any real-time parameters.

Dynamic model:

• The dynamic model uses the combination of the outputs from various subsystems to generate the output.
• Here real-time parameters are taken from the vehicle with the input as the drive cycle of our requirement and the simulation is done.
• The results from all the subsystems added up to the total output of the simulation.
• The accuracy of this model is very high as it considers the real-time parameters.
• The stimulation time will be higher as it has many individual subsystems to run and which constitutes the overall output of the system.

Steps to change the model type:

• First, choose the required model.
• Then right-click on that model and move the cursor to the "variant" option and then click it.
• There we see two options, one for mapped and for the dynamic model.
• choose the required type of model and perform further simulation process.

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

Solution:

where can we find the miles per gallon:

model:

Pure electric vehicles only need battery supply to perform, but we can see the above fig. there are two inputs one is vehicle speed and the other is batter power.

Calculation:

• The battery power is converted to KW units by giving to product block.
• This KW is converted to gallons per hour by dividing it by 33.7 kWh/gal per hour.
• Then it is further converted to the gal from m3 per gal.
• m3 per gal is converted to US Gal by multiplying with 264.172.

now we will take the vehicle speed input.

• First, the vehicle speed in m/s is converted to m by using the product, square root blocks, and integrator blocks.
• Then m is converted to miles by multiplying with 0.000621371.
• Then mile and US gallons are combined using the element-wise "*/" block to get the miles per gallon.

factors are considered to model fuel flow:

• Vehicle speed.
• Battery power.

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

Solution:

Model: Hybrid electric vehicle multimode reference model

WOT parameters:

changing the values of grade and wind velocity:

Grade = 6

wind velocity =15

Results:

Simulation time=100 seconds

Observation:

plot1:

We can see that the vehicle cannot reach its top speed due to wind velocity acting on it and at the time of 50-sec deceleration occurs and it came to zero.due to wind velocity aginst the vehicle the speed becomes negative for some times (i.e) below 0 as we can see in the plot 1 which show the impact of wind velocity is high during deceleration than during acceleration.

plot2:

This plot shows the change in the speed of the motor, engine, generator in rpm where motor reached to 9014 rpm but the generator reached 5371 rpm.

plot3:

This shows how the torque changes in motor, generator, engine. Up to 17 sec, the torque of the motor and the generator were the same and the engine torque was the vehicle running in wind velocity condition which leads to the driving the vehicle with more capacity so the engine torque is higher. After deceleration completed the motor and engine torque remains the same where there is no work on the generator which keeps the torque below zero.

plot4:

This plot tells the battery current data, where up to 1.5 sec there is no use of motor so it remains as close to zero after sec there is acceleration in the vehicle which makes engine and motor to drive fast, so the supply of current from battery increases up to 19 sec after that deceleration occurs the supply from the battery gets reduced.

plot5:

This plot is used to show the state of charge of the battery, the SOC of the battery has fallen from 80 % to 61 % for the given drive cycle.

plot6:

This plot shows the fuel consumption in miles per gallon for the given drive cycle, and for WOT it is 4-8 miles per gallon.

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

solution:

For comparison of the Hybrid and pure electric vehicle, we can use the above have the model of Hev for comparison with the pure electric vehicle model.

Model: Electric vehicle model.

WOT parameters:

grade and wind velocity parameters:

Results:

Observation:

plot1:

The velocity achieved is less in this drive cycle compared to the HEV model and we can see the speed doesn't become negative due to wind velocity and deceleration in the Electric vehicle model.

plot2:

The motor speed increases with the vehicle speed proportionally and at a constant vehicle speed it remains stable and during deceleration of the vehicle, it decreases.

plot3:

The torque remains the same at the initial increase of time, It increases with the increase in the pickup speed and later at a constant speed it becomes constant.

plot4:

The SOC of the battery is more efficient in case of the electric vehicle were it just a loss of 4% from 80% to 76

plot5:

This plot shows the motor took high current at initial stages where the torque is high to pick up speed compare to the later stage of the drive cycle.

plot6:

This plot shows the fuel consumption in miles per gallon for the given drive cycle, and for WOT it is 25 miles per gallon which is way more than the HEV model.

Conclusion:

The overall efficiency of an Electric vehicle is more than the Hybrid Electric Vehicle.

We can say that more distance can be traveled in HEV than in pure electric vehicles for the same amount of fuel.

The battery discharge rate is less in Electric vehicles than in the hybrid electric vehicle.