Week-4 Challenge WOT Condition Part-2

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

MAPPED models:

Mapped models are used when the behavior 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:

in the below model values are taken from experiments or old data

Implements 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 includes a motor and drive response time constant. Also have to Specify electrical 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. motor model:

in the below model, motor components such as inverter, phase controller, feedback circuits are also modeled.

CHANGING the model type in EV powertrain 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.

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

Simulink block to calculate miles per gallon.

• vehicle speed data is used to calculate the distance traveled in meters which is then converted to miles
• Battery power data is used to find power used in kWh which is then converted to gasoline-equivalent using US EPA value by dividing with 33.7
• note: As per the US environmental protection agency(EPA) 1 gallon of gasoline is equal to 33.7 kWh
• Dividing distance traveled in miles by the number of gallons, we can get miles per gallon.
• For HEV this gallon(gasoline-equivalent of battery power) is added with gallon used by IC engine then miles per gallon is calculated

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

Open the HEV reference application

Grade - 0, wind velocity 0m/s

Grade - 5, wind velocity 10m/s

Grade - 15, wind velocity 30m/s

RESULTS:

with the increase in grade and wind velocity,

• peak velocity achieved 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.
• deceleration time is reduced so batter recharging capacity is also reduced.
• Battery SOC at the end of WOT acceleration is similar but during deceleration battery is charged more is the grade and wind velocity is less.

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

Simulation conditions:

simulation is done for 50 seconds and the 40 seconds WOT drive cycle is used with wot acceleration for 0-30 seconds achieving a max speed of 26.8m/s and decelerates for 10 seconds (30-40).

EV model powertrain configuration:

HEV p2 model:

HEV p2 model is chosen because the configuration is similar to our EV model

Simulink model:

Results:

1.EV model

2.HEV P2 Model

SUMMARY:

• Time taken to achieve the required peak velocity is less for HEV as compared to EV
• Deceleration time is also low for HEV as it has many moving frictional parts
• fuel economy is more for an EV compared to HEV due to less no of moving parts and thus low frictional losses