Week-4 Challenge WOT Condition Part-2

Ans 1)

Mapped Model:

Mapped model also known as static model takes in motor data i.e. required motor torque/engine torque and motor or engine block generates the required output without considering the actual parametres of engine and generator.

The accuracy of mapped(static) model is not high since it does not use any real time parametres. Hence it loads the simulation faster.

Dynamic Model:

Dynamic model uses output from subsystems to generate the output. It performs a real time simulation with drive cycle data. Vehicle feedback with initial bus voltage and current is given so that it runs the actual simulation for every point in drive cycle.

The accuracy is very high for this model since it considers real output from all subsystem. Therefore simulation will take a bit longer since the subsystems are also performing their own simulation to generate the output.

Changing the model type: When the vehicle model is selected i.e. EV/Hybrid/Gasoline powered The simulink model appears with all the main blocks.

Select passenger block in that open electrical plant. In electrical plant there will be two main blocks i) battery ii) motor generator

The motor generator block gives the option to select mapped or dynamic model.

Ans 2)

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 case of electric vehicle, 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 electrical energy required to move the car through the same distance and is expressed as miles per gallon.

The powertrain blockset has a model that calculates the miles per gallon for all kinds of vehicle.

The model above takes in Vehicle velocity, Flow of the fuel and Battery power to calculate the fuel consumption and equivalent battery consumption and calculates miles per gallon.

• The vehicle speed is important factor while considering the fuel consumption throughout the drive cycle.
• To convert speed to distance we integrate with time and same is to be done to convert velocity to distance.
• Then 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 fuel and by usnig this 1 we convert it to the volume and by multiplying it by 1000 we get it in litres.

Battery Power:

• The amount of energy from the battery power required to propel the vehicle equivalent to that of the engine is calculated here.
• We convert power into energy by multiplying with time to get KWh.
• Then we convert the energy from kwh to equivalent energy un US gallon of automotive gasoline by dividing with 33.7.
• Dividing it by 3600 to convert hour to seconds will give the equivalent energy LIS gallons per seconds.
• Multiplying with 0.00378541 we convert the US gallons per sec to volume of the fuel flow in (mA3/s) and then we multiply with 739 (California Phase II Gasoline density i.e. (mA3/s*kg/mA3) which gives result as mass flow rate.
• Then finally the battery energy equivalent in kg/s is given as input for the fuel flow parameter in order to find the equivalent US gallons energy estimate the Miles per Gallon.

Calculatng miles per gallon:

• Then the inputs from the vehicle speed i.e. the distance we found in metres is taken into the calculation and it is converted to the miles by multiplying with 0.000621371.
• Then the input from fuel fow taken in mA3 and is converted into equivalent US Gallons by multplying with 264.172.
• Then the two input miles covered and equivalent US Gallon is further divided and the result is obtained in Miles/Gallon.

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

Hybrid Electric Vehicle:

• A hybrid electric vehicle combines a conventional IC engine system with an electric propulsion system.
• The presence of electric powertrain is intended to achieve either better fuel economy than a conventional vehicle or better performance.

CASE 1:

Simulation condition: The simulation is done with a wide open throttle (WOT) drive cycle.

Cycle time: 100 seconds

Maximum speed attained: 80 mph

Time to start deceleration: 48 seconds

Grade angle: 0 degree

Wind velocity: 0 m/s

Then 1 & 2 cursor on plots are used to measure the instantaneous values of that particular location.

The above figure shows the Performance and FE scope for Case 1 simulation criteria.

Plot 1: Shows velocity of the vehicle w.r.t drive cycle with x-axis as time scale.

The top speed of 180 mph cannot be achieved due to additional forces and losses.

Acceleration time to attain the highest speed of 115 mph: 48 seconds

Deceleration time from 115 mph to minimum: 6.5 seconds

Plot 2: Shows changes in motor speed(RPM) throughout the drive cycle.

Peak motor speed: 13800 RPM

Peak Engine speed: 5340 RPM

Peak Generator speed: 5340 RPM

Plot 3: Shows the torque characterstics and its changes throughout the drive cycle.

Peak engine torque: 170 Nm

Peak Generator torque: 170 Nm

Peak motor torque during acceleration: 306 Nm

Plot 4: Shows the battery state of charge throughout the drive cycle.

The battery state of charge decreased from 80 % to 62 % in a time period of 48 seconds.

Plot 5: Shows the current drawn from the battery and current given to the battery during deceleration.

Peak current discharge: 511 A

Peak current charge to the battery: 275 A

Plot 6:Shows the equivalent fuel economy as miles per gallon for the corresponding input driving conditions. In this case, there is no fuel in pure electric vehicle. However this gives equivalent battery energy required to that of fuel energy and calculates the fuel efficiency.

The maximum miles that car can run per gallon of fuel equivalent: 13.5 MPG

CASE 2:

Simulation condition: The simulation is done with a wide open throttle (WOT) drive cycle.

Cycle time: 100 seconds

Maximum speed attained: 80mph

Time to start deceleration: 48 seconds

Grade angle: 10 degree

Wind velocity: 7 m/s

The above figure shows the Performance and FE scope for Case 2 simulation criteria.

Plot 1: Shows velocity of the vehicle w.r.t drive cycle with x-axis as time scale.

The top speed of 180 mph cannot be achieved due to additional forces and losses.

Acceleration time to attain the highest speed of 61.3 mph: 40 seconds

Deceleration time from 61.3 mph to minimum: 2.8 seconds

Plot 2: Shows changes in motor speed(RPM) throughout the drive cycle.

Peak engine speed: 5425 RPM

Peak motor speed: 9500 RPM

Peak Generator speed: 5425 RPM

Plot 3: Shows the torque characterstics and its changes throughout the drive cycle.

Peak Engine Torque: 170 Nm

Peak motor torque during acceleration: 307 Nm

Peak motor torque during deceleration: 175 Nm

Peak Generator Torque: -170 Nm

Plot 4: Shows the battery state of charge throughout the drive cycle.

The battery state of charge decreased from 80 % to 62 % in a time period of 47 seconds.

Plot 5: Shows the current drawn from the battery and current given to the battery during deceleration.

Peak current discharge: 525 A

Peak current charge to the battery: 265 A

Plot 6:Shows the equivalent fuel economy as miles per gallon for the corresponding input driving conditions. In this case, there is no fuel in pure electric vehicle. However this gives equivalent battery energy required to that of fuel energy and calculates the fuel efficiency.

The maximum miles that car can run per gallon of fuel equivalent: 5.8 MPG

4) Keeping all the parameters same, compare the simulated results of hybrid and pure electric power train.

Pure Electric Vehicle:

• A battery electric vehicle or pure electric vehicle is an EV that exclusively uses chemical energy stored in rechargable battery packs with no secondary source of propulsion of energy.
• They don't produce any emission of waste gas making them eco-friendly.
• They have there own limitations.

The above figure shows diagram of components of electric vehicle used to run it.

CASE 1:

Simulation condition: The simulation is done with a wide open throttle (WOT) drive cycle.

Cycle time: 100 seconds

Maximum speed attained: 80mph

Time to start deceleration: 48 seconds

Grade angle: 0 degree

Wind velocity: 0 m/s

The above figure shows the environment variables.

The above figure shows the Performance and FE scope for Case 1 simulation criteria.

Plot 1: Shows velocity of the vehicle w.r.t drive cycle with x-axis as time scale.

The top speed of 180 mph cannot be achieved due to additional forces and losses.

Acceleration time to attain the highest speed of 108 mph: 48 seconds

Deceleration time from 108 mph to minimum: 10 seconds

Plot 2: Shows changes in motor speed(RPM) throughout the drive cycle.

Peak motor speed: 11320 RPM

Plot 3: Shows the torque characterstics and its changes throughout the drive cycle.

Peak motor torque during acceleration: 280 Nm

Peak motor torque during deceleration: 228 Nm

Plot 4: Shows the battery state of charge throughout the drive cycle.

The battery state of charge decreased from 80 % to 75 % in a time period of 46.7 seconds.

Plot 5: Shows the current drawn from the battery and current given to the battery during deceleration.

Peak current discharge: 218 A

Peak current charge to the battery: 170 A

Plot 6:Shows the equivalent fuel economy as miles per gallon for the corresponding input driving conditions. In this case, there is no fuel in pure electric vehicle. However this gives equivalent battery energy required to that of fuel energy and calculates the fuel efficiency.

The maximum miles that car can run per gallon of fuel equivalent: 33.2 MPG

Case 2:

Simulation condition: Done for pure electric vehicle with WOT drive cycle.

Cycle time: 100 seconds

Maximum speed attained: 80mph

Time to start deceleration: 48 seconds

Grade angle: 10 degree

Wind velocity: 7 m/s

Shows the environment variables for grad and wind velocity.

The above figure shows the the performance and FE scope for case 2 simulation criteria.

Plot 1: Shows velocity of the vehicle w.r.t drive cycle with x-axis as time scale.

The top speed of 180 mph cannot be achieved due to additional forces and losses.

Acceleration time to attain the highest speed of 51 mph: 48 seconds

Deceleration time from 51 mph to minimum: 4 seconds

Plot 2: Shows changes in motor speed(RPM) throughout the drive cycle.

Peak motor speed: 5500 RPM

Plot 3: Shows the torque characterstics and its changes throughout the drive cycle.

Peak motor torque during acceleration: 280 Nm

Peak motor torque during deceleration: 228 Nm

Plot 4: Shows the battery state of charge throughout the drive cycle.

The battery state of charge decreased from 80 % to 75 % in a time period of 46.2 seconds.

Plot 5: Shows the current drawn from the battery and current given to the battery during deceleration.

Peak current discharge: 218 A

Peak current charge to the battery: 160 A

Plot 6:Shows the equivalent fuel economy as miles per gallon for the corresponding input driving conditions. In this case, there is no fuel in pure electric vehicle. However this gives equivalent battery energy required to that of fuel energy and calculates the fuel efficiency.

The maximum miles that car can run per gallon of fuel equivalent: 17.8 MPG.

Observation(Pure EV vs Hybrid EV with WOT load condition):

1. The electric vehicle when compared with hybrid electric vehicle with same environmental and drive cycle conditions shows less maximum speed achievement. The electric vehicle produces more values of motor speed and motor torque compared to the hybrid vehicle's motor alone mode, but hybrid vehicle when uses both engine and motor torque it is higher than EV's torque.

2. As pure electric car uses Lithium-ion battery compared to the Nickel metal hydride battery the discarging capacity and the rate of charging is higher in the pure electric car. As it is able to discharge in a fast rate it can produce higher torque instantly as compared to hybrid one.And also SOC shows the battery efficiency of pure EV to be higher than hybrid EV.

3. Efficiency of pure EV is higher than hybrid car when both of these plot of miles per gallon are compared.

4. Electric vehicle produces zero emission whereas hybrid one produces waste gas emission.