Week-4 Challenge WOT Condition Part-2

Question no 1

Mapped and Dynamic subsystem of Electric Motor/Generator

Mapped Model:

• The mapped model is one type where the data points are pre_assigned in lookup tables.
• The engine or motor torque required is sensed and the motor or engine block generates the necessary torque output just as simply needed without considering the real-time motor or engine, parameters
• The output values are stored for the corresponding given input values of the engine motor and generator.
• The accuracy of this type is not that high but the simulation will be done in much less time as it does not run by real-time parameters.

Dynamic Model:

* The dynamic model on the 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 individual 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, and current is given along with the vehicle feedback so that it runs the actual simulation at that particular moment throughout the drive cycle.

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

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

* The figure below shows the working phase of the dynamic model.

Steps to select the Model Type:

• In the powertrain block set module, we first need to select the vehicle type first whether it is a full electric, full engine, or type of hybrid vehicle.
• After that, the Simulink model appears by showing the workflow blocks of the model.
• In that, we need to go to Passenger Block Electric plant* EV Motor/Generator block.
• After this just right-click and go to Variance Label mode Active choice MotorGenEV Mapped or Dynamic.

Question no 2

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 an Engine powered car.
• In the case of an electric vehicle, it tells us the energy which is equivalent to that of an engine-powered car to propel the car through a distance.
• The amount of Fuel Energy required to move an engine-powered car through a distance is determined and then it is compared to the equivalent amount of electric energy required to move the car through the same distance and is expressed as the miles per gallon.
• The powertrain block set has a model that calculates the miles per gallon for all kinds of vehicles.

• 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 an important factor when 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 by converting the velocity to get the 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 multiply by 1000 to get it in Litres.
• By comparing the two results we can get the amount of liter 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 by 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 gallons of automotive gasoline by dividing by 33.7. since we get the energy in US Gallons equal to KWh we are trying to get the energy of equivalent LIS Gallons per second and we do this by dividing by 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 an input for the fuel flow parameter in order to find the equivalent US Gallons of energy and estimate the Miles per Gallon.

Calculating Miles Per Gallon :

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

Question no 3

Hybrid Electric Vehicle:

• A hybrid electric vehicle (HEV) is a type of hybrid type that combines a conventional Internal combustion engine (ICE) system with an electric propulsion system
• The presence of the electric powertrain is intended to achieve either better fuel economy than a conventional vehicle or better performance.
• An example of HEV is Toyota Prius.

• In the powertrain blockset, we have selected the hybrid electric vehicle and this is the Simulink model.
• Here we can select the input parameters as we wish and we can Run the simulation to check the results.

Case1

Simulation condition:

The simulation is done for Hybrid electric vehicle with Wide open Throttle Drive cycle.The Total cycle time = 100 seconds

The Top speed of this cycle = 80 mph

Time to start deceleration = 50seconds

The Grade angle = 0 degrees

The wind velocity = 0 m/s

plot 1:

Shows the velocity of the vehicle with respect to the Drive cycle data with the Time scale on the x axis.

The top speed of 80 mph cannot be achieved as we have some additional forces acting and so the car can only run upto 108.9mph

The acceleration time to reach top speed of 108.9 mph = 50.2 seconds

The deceleration time from 80 to minimum = 9.8 seconds

plot 2:

Shows the changes in speed of the Motor in Rpm throughout the drive cycle.

Peak Motor speed = 1123 Rpm

plot 3:

Shows the Torque characteristics and its changes of Motor in (Nm) throughout the drive cycle.

Peak Motor torque = 260 Nm

plot 4:

Shows the Battery Current values (A) and its changes for various acceleration inputs as per the Drive cycle.

The peak current discharge from the battery = 216.8 A

The peak current charging to the battery = -173.7 A

Plot 5:

Shows the Battery state of charge SOC (%) and its changes corresponding to the driving inputs.

The state of charge decreased from 80% to 75.5% of charge in a time period of 50.3 seconds, for the specified driving conditions.

Plot 6:

Shows the Equivalent Fuel Economy as Mile per Gallon for the corresponding input driving conditions. Here there is no fuel in the pure electric vehicle however this gives equivalent battery energy required that of the fuel energy and calculates the Fuel efficiency. The maximum miles that the car can run per gallon of fuel equivalent = 20.45 Miles,for the given vehicle at the specified driving conditions.

Case2

Simulation Condition:

The simulation is done for pure electric & Hybrid electric vehicles with Wide open Throttle (WOT) Drive cycles.

The Total cycle time = 100 seconds

The Top speed of this cycle = 80 mph

Time to start deceleration = 50 seconds

The Grade angle = 8 Degrees

The wind velocity = 10 m/s.

plot 1:

Shows the velocity of the vehicle with respect to the Drive cycle data with the Time scale on the x axis.

The top speed of 80 mph cannot be achieved as we have some additional forces acting and so the car can only run upto 58.9mph

The acceleration time to reach top speed of 58.9 mph = 48.8 seconds

The deceleration time from 80 to minimum = 4.63 seconds

plot 2:

Shows the changes in speed of the Motor in Rpm throughout the drive cycle.

Peak Motor speed = 6254 Rpm

plot 3:

Shows the Torque characteristics and its changes of Motor in (Nm) throughout the drive cycle.

Peak Motor torque = 280 Nm

plot 4:

Shows the Battery Current values (A) and its changes for various acceleration inputs as per the Drive cycle.

The peak current discharge from the battery = 225.8 A

The peak current charging to the battery = -163.7 A

Plot 5:

Shows the Battery state of charge SOC (%) and its changes corresponding to the driving inputs.

The state of charge decreased from 80% to 75.5% of charge in a time period of 49 seconds , for the specified driving conditions.

Plot 6:

Shows the Equivalent Fuel Economy as Mile per Gallons for the corresponding input driving conditions.Here there is no fuel in pure electric vehicle however this gives equivalent battery energy required that of the fuel energy,and calculates the Fuel efficiency.The maximum miles that the car can run per gallon of fuel equivalent = 21.45 Miles,for the given vehicle at the specified driving conditions.