Week-4 Challenge WOT Condition Part-2

#solution 1

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.

The dyanamic model in other hand uses the combination of the outputs from various subsystems to generate the output.

* It runs by real time simulation where the required input from the drive cycle is taken and for that individiual real time simulation gets performed and summing all the results of the subsystem gives the output for the simulation.

* As per the drive cycle requirements the initial Bus voltage ,current is given along with the vehicle feedback so that it runs the actual simulation at that particuclar moment throught the drive cycle.

* The accuracy of this model is very high as it considers the real outputs from all the subsystem to generate the output.

* The simulation will take very long time to complete as it has so many individual simulations running by all the subsystem of the engine , motor/generator.

eg. motor model:

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

Miles per gallon

• Miles per Gallon is a fuel economy rating determined by how far a car can travel on a gallon of petrol or Diesel for a Engine powered car.
• In case of an electric vehicle it tells us the energy which is equivalent that of a engine powered carto propel the car through a distance.
• The amount of Fuel Energy required to move a engine powered car through a distance is determined and then it is compared to the eqivalent amount of electric energy required to move the car throgh the same distance and is expressed as the miles per gallon.
• The powertrain blockset has a model that calculates the miles per gallon for all kinds of vehicle.

• The above model takes the input of the Vehicle speed , Fuel flow and Battery power to calculate the fuel consumption and the equivalent battery consumption and calculates the miles per gallon.

Vehicle Speed And Fuel Flow:

• The Vehicle speed is a important factor while considering the fuel consumption at that particular time,so to determine the fuel consumption throughout the drive cycle.
• To convert speed to Distance we can Integrate with time and we are doing the same of converting the velocity to get distance covered by integrating.
• Then the Fuel flow is expressed as the mass flow rate (i.e) the amount of fuel at each moment in Kg/Sec. Now integrating this will result in the mass of the fuel and by using this 1 we convert it to the volume and by multiply by 1000 to get it in Litres.
• By comparing the two results we can get the amount of litre consumed to Run for 100km.

Battery Power:

• The amount of Energy from battery power required to propel the vehicle Equivalent to that of the Engine is calculated here.
• The battery power is given in watts and it is converted to Kw by dividing with 1000.
• Then we convert the power into energy by multiplying with the time into KWh.
• Then we convert the Energy from kWh to equivalent energy in US gallon of automotive gasoline by dividing with 33.7. since we get the energy in US Gallons equal in KWh we are trying to get the energy of equivalent LIS Gallons per seconds and we do this by dividing with 3600 and we convert the hour to seconds.
• Then multiplying with 0.00378541 we convert the US Gallons per sec to the volume of the fuel flow in (mA3/ s) and then we multiply with 739 (California Phase Il Gasoline density) (i.e) mA3/s * kg/mA3 which gives the result as mass flow rate kg's.
• Then finally the Battery energy equivalent in kg/s is given as a input for the fuel flow parameter in order to find the equivalent US Gallons enegy and estimate the Miles per Gallons.

Calculating Miles Per Gallon :

• Then the inputs from the vehicle speed (i.e) the Distance we found (in meters) is taken into the calculation and it is converted to the miles by multiplying with 0.000621371.
• Then the inputs from fuel flow (Battery energy + Fuel energy) taken in mA3 and is converted into equivalent US Gallons by multiplying with 264.172.
• Then the two inputs Miles covered and equivalent US Gallon is further divided and the result is got in Miles / Gallon.

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