Week-4 Challenge WOT Condition Part-2

Objective:

The main objective is stated as below:

1. What is the difference between the mapped and dynamic models of engine, motor, and generator? How can you change the model type?
2. How does the model calculate miles per gallon? Which factors are considered to model fuel flow?
3. Run the HEV Reference Application with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.
4. Keeping all other parameters the same, compare the simulated results of hybrid and pure electric powertrains.

Theory:

Power Train:

The powertrain consists of the power source (engine) and all of the components that convert the engine's power into the movement of the vehicle (transmission, driveshafts, differential, and axles). Whereas the drivetrain does not include the power source and consists of the transmission, driveshafts, differential, and axles.

Procedure:

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

Power Train Blockset provides two types of combustion engine models as stated below.

Mapped:

Mapped engines represent macro engine behavior as a set of lookup tables (brake torque, fuel flow, air mass flow, exhaust temperature, efficiency, and emissions) as functions of commanded load and measured engine speed.

Mapped engine models are suitable for analysis and design activities that do not require engine subsystem dynamic characteristics.

Dynamic:

Dynamic engines decompose engine behavior into individual component models that account for engine dynamics, most notably intake airflow and turbocharger dynamics.

Dynamic engine models are suitable for designing control, estimator and diagnostic, algorithms that depend on dynamic subsystem states.

To change the models between mapped and dynamic models:

• Open the Powertrain module block-set for the required vehicle say (EV).

• Click on passenger car/vehicle block and select electric plant or engine.

• Right-click on the motor block and click variant option >> Label Mode Active Choice and change it to your required model.

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

• Miles per gallon (MPG) is a fuel economy rating determined by how far a car can travel using a gallon of fuel (i.e. gasoline or diesel for IC engines).
• In the case of an electric vehicle, the electrical energy is consumed by the battery pack to travel a fixed distance.
• The inputs which are taken into consideration are the vehicle speed, fuel flow, and battery power.

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 Power train block set in the help section and select the Hybrid Electric Vehicle (HEV)- Multimode and open the model.

• A new Simulink model is opened.

• Double- Click on the Drive Cycle Source, a new dialog box opens
• In the Drive Cycle source, select the Wide Open Throttle (WOT) and click OK.

• Now, In the Environment block, initially, check the grade and Wind velocity (they are taken as 0).

• Run the model and open the Visualization of the performance and FE scope.

• Now change the Grade and Wind Velocity to 5 degrees and 10 m/s and run the model.

• Following the same now change the grade and wind velocity to 10 degrees and 10 m/s and run the model again.

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

• Open the Electric Vehicle Reference application in the Powertrain block set.

• Run the Model without changing any parameters.
• Check the graphs.

• Also, open the HEV reference Application in the Powertrain block set.

• Run the Model as it is and observe the graphs.

Results:

1. Changing grade and wind velocity for HEV:

• The trace velocity graph has a major difference as the actual trace velocity is decreasing with the increase in wind velocity.
• The Engine speed is reduced as the wind velocity creates an air drag which slows the vehicle. Hence it requires more energy and time to reach the maximum speed.
• With the increase in wind velocity and grade, the battery is drained fast and fuel consumption increases.

2. HEV vs EV:

• The top speed is seen in the Hybrid Electric vehicle model compared to Full Electric Vehicle.
• The fuel economy is higher in EV.
• The battery SOC is higher in EV compared to HEV.

Learning Outcomes:

• Learned to observe the power train block set and check how the model is working when the parameters are changed.