Week-4 Challenge WOT Condition Part-2

Q1: What is the difference between the mapped and dynamic model of engine,motor and generator? How can you change the model type?

A1: Mapped model:

Mapped models ar eused the behaviour of a particular model is not of our interest and can be modeled with predefined values in the form of lookup tables.

Eg: Mapped motor: Implement a mapped motor and drive electronics operating in torque control mode. We have to specify electrical torque range with a torque-speed envelope or maximum motor power and torque. Output torque tracks a torque reference demand and concludes amotor and drive response time constant. Also have to specifyelectrical losses as a single operating point that estimates loss across the operating range, measured loss, or measured efficiency.

Dynamic model:

Dynamic models are used when the internal response to a model with respect to its components is needed.

Eg: Dynamic motor: In the model, motor components such as inverter, phase controller, feedback circuits are also modeled.

Changing the model type in EV power train blocks:

We can use the variant manager in the modeling tab to find the variant systems we have:

Right click on the model you want and use 'set as Label mode active choice'.

Q2 : How does the model calculate miles per gallon? Which factors are considered to model fuel flow?

Simulink block to calculate miles per gallon.

Conversation from Cubic meter to gallon(m^3 to gallon).

As we know 264.172 US gallons is 1000L.

The reference model taken here for consideration is HEV and as it operates on both the battery and the fuel injection Engine.

The final output/Fuel Efficiency is calculated by keeping in consideration of the Battery output. Fuel ouput and the vehicle speed/kilometers driven.Therefore the fuel efficiency is calculated and it is converted after the saturation thus the FE is calculated.

Q3: 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 HEV reference application and change parameters speed,declaration time and WOt simulation time. After the cange the parameters and run the simullation and see the results. After change the Grade and wind velocity is 10 and 20m/s and run the simulation see the results.

Results: With the increase in grade and wind velocity,

• Peak velocity achived is reduced as gradient force and aerodynamic force becomes dominant.
• Fuel economy is also reduced because the distance traveled is reduced due to external forces.
• Declaration time is reduced so batter recharging capacity is also reduced.
• Battery SOC at the end of WOT acceleration is similar but during declaration battery is charged more is the grade and wind velocity is less.

Q4 : Keeping all other parameters the same, compare the simulated results of hybrid and pure electric powertrains.

Simulation conditions : Simulation is done for 100 secs and the 100 secs WOT drive cycleis used with WOT accleration for 0-80 seconds achieving a max speed of 70m/s and decelerates for 10 secs (80-90). We can use the parameters in Ev reference and HEV reference models.

Summary:

1. Time taken to achieve the required peak velocity is less for HEV as compared to EV.
2. Declaration time is also low for HEV as it has many moving frictional parts.
3. Fuel economy is more for an EV compared to HEV due to less no of moving parts and thus low frictional losses.