Week-4 Challenge WOT Condition Part-2

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

soln :

Powertrain Blockset : It provides fully assembled reference application models of automotive powertrains, including gasoline, diesel, hybrid, and electric systems. It includes a component library for simulating engine subsystems, transmission assemblies, traction motors, battery packs, and controller models. Powertrain Blockset also includes a dynamometer model for virtual testing. MDF file support provides a standards-based interface to calibration tools for data import.

Powertrain Blockset provides a standard model architecture that can be reused throughout the development process. You can use it for design tradeoff analysis and component sizing, control parameter optimization, and hardware-in-the-loop testing. You can customize models by parameterizing components in a reference application with your own data or by replacing a subsystem with your own model.

Powertrain Blockset provides two types of combustion engine models: mapped and dynamic.

A) Difference between mapped and dynamic model of engine, motor and generator

Mapped engines represent macro engine behavior as a set of lookup tables (brake torque, fuel flow, air mass flow, exhaust temperature, efficiency, and emissions) as functions of commanded load and measured engine speed.Mapped engine models are suitable for analysis and design activities that do not require engine subsystem dynamic characteristics, for example, in engine and transmission powertrain matching analysis for fuel economy, emissions, and performance tradeoffs.

Dynamic engines decompose engine behavior into individual component models that account for engine dynamics, most notably intake airflow and turbocharger dynamics.Dynamic engine models are suitable for designing control, estimator, and diagnostic algorithms that depend on dynamic subsystem states, for example, in closed-loop AFR control algorithm development.

You can switch between engine model types based on your application.

Steps to change model type :

• First open the powetrain blockset module and select for the desired vehicle type model.
• Then the simulink model appears ,with workflow blocks.

• Now open the passenger car block and select the electric plant block.

• Then select the 'MotGenEVMapped' block.

• Now for changing mapped to dynamic blockset, right click on the screen and select variant. Then select label mode active choice and select MotGenEVDynamic.

• Similarly we can change from dynamic to mapped by selecting MotGenMapped option.

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

Soln :

Miles per Gallon(MPG) :

• Miles per Gallon is 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 vehicles ,this can be defined as the amount of distance travelled by the engine powered car in a gallon of fuel and compared with the electric energy required by the electric vehicle to travel the same distance i.e, the equivalent energy required to propel the car through same distance.
• The powertrain blockset has a model that calculates the miles per gallon for all kinds of vehicle.
• Open "HevMmReference' application model in matlab and inside the 'Visualization block'. Now open the 'Performance Calculations block',here we can see the blocks which are used for calcultion of MPG.

• The above 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 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 US 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 (mA2/s) and then we mulitply with 739(California Phase ll Gasoline density)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 energy and estimate the Miles per Gallons.

Calculating Miles Per Gallon :

• Then the inputs from the vehicle speed i,e.. the distance we found is taken into the calculation and its 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 multipying with 264.172.
• Then the two inputs Miles covered and equivalent US gallons is further divided and the result is got in Miles per Gallon.

Q3. Run the HEV ReferenceApplication with WOT drive cycle. Change the grade and wind velocity in the environment block. Comment on the results.

Soln :

Hybird Electric Vehicle :

• A hybird electric vehicle(HEV) is a type of hybird 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.
• Example of HEV is Toyota Prius.

By default ,the HEV multimode reference application is configured with

• Mapped motor and generator
• 1.5-L spark-ignition (SI) dynamic engine

HEV Reference Application Model :-

• In the powertrain blockset we have selected the hybird electric vehicle and this is the simulink model.
• Here we can select the input paramters as we wish and we can Run the simulation to check the results.

Case 1

Simulation condition :

The simulation is done for Hybird Electric Vehicle with Wide Open Throttle as drive cycle.

The total cycle time = 100 seconds

The top speed of this cycle = 80 mph

Time to start deceleration = 50 seconds

The Grade angle = 0 degrees

The wind velocity = 0 m/s

Result :

• The above figure shows the results for the simulation and there are totally six plots in them.
• Each plot shows a particular result and the plots are made in such a way that ,there is a cursor measurement and if we change the cursor on one plot the cursor moves on the other plots too which paves way to study the result in a better way.
• The cursor enables us to study the behaviour of the other result parameters corresponding to the accleration of the vehicle.

Plot 1:

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

The acceleration time to reach 80 mph is at 16.7 seconds

The deceleration time from 80 to minimum is 6.2 seconds

Plot 2:

Shows the changes in speed of the Engine ,Motor and Generator in RPM throughout the drive cycle.

Peak Engine speed = 4780 RPM

Peak Motor speed = 9497 RPM

Peak Generator speed = 13690 RPM

Plot 3:

Shows the Torque characteristics and its changes of engine ,motor and generator in (Nm) throughout the drive cycles.

Peak Engine Torque = 138.7 Nm

Peak Motor Torque = 206.7Nm

Peak generator Torque = 42.2 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 = 163.5 A

The peak current charging from the battery = -150.86 A

Plot 5 :

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

The state of charge decreased from 60% to 39.8% of charge in a time period of 49.3 seconds, for the specified driving conditions.

Plot 6 :

Shows the Fuel Economy as Miles per Gallons for the corresponding input driving conditions.

The maximum miles that the car can run per gallon of fuel equivalent = 46 Miles , for the given vehicle at the specified driving conditions.

Case 2 :

Simulation condition :

The simulation is done for Hybird Electric Vehicle with Wide Open Throttle drive cycle with below condition by adding values grade angle and wind velocity :

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

Environment Block :

Result :

• In all the above results we can observe some changes from the previous case
• Though the vehicle parameters and the drive cycle are the same ,here we have considered some changes in the environment blocks by adding some climb angles and wind velocity.

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 run maximum speed of upto 68.6 mph

The accleration time to reach the top speed of 68.6 mph is 50 seconds

The deceleration time from maximum mph to minimum is 3.448 seconds

Plot 2:

Shows the changes in speed of the Engine ,Motor and Generator in RPM throughout the drive cycle.

Peak Engine speed = 4676 RPM

Peak Motor speed = 8103.5 RPM

Peak Generator speed = 12858.5 RPM

Plot 3:

Shows the Torque characteristics and its changes of engine ,motor and generator in (Nm) throughout the drive cycles.

Peak Engine Torque = 139.6 Nm

Peak Motor Torque = 206.4 Nm

Peak generator Torque = 48.2 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 = 167.6 A

The peak current charging from the battery = -152.46 A

Plot 5 :

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

The state of charge decreased from 60% to 25.98% of charge in a time period of 49.3 seconds, for the specified driving conditions.

Plot 6 :

Shows the Fuel Economy as Miles per Gallons for the corresponding input driving conditions.

The maximum miles that the car can run per gallon of fuel equivalent = 17.93 Miles , for the given vehicle at the specified driving conditions.

Observation :

• The simulation results for both the cases is done and we can see that the simulation 1 without the inclusion of hill climbing conditions and the wind drag velocity is much more efficient when compared to the simulation which includes the hill climbing angle conditions and the wind drag velocity.
• In case2 the vehicle was not able to achieve the required top speed though using the highest possible current discharge of that same battery used before.
• The state of charge also shows that the discharge is also high compared to the simulation case 1.
• The fuel Economy is also down to half of the previous simulation.
• So it is evident that the efficiency of no load vehicle is high compared to the vehicle with additional loads acting on them and also we have visualized this using the Powertrain blockset.

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

Soln :

By comparing pure electric powertrains with previous hybird electric powertrains.

• A battery electric vehicle or pure Electric vehicle is a EV that exclusively uses chemical energy stored in rechargeable battery packs with no secondary source of propulsion (e.g. hydrogen fuel cell ,internal combustion engine etc) of energy.
• BEVs use electric motors and motor controllers instead of an conventional Internal Combustion engines for propulsion. They derive all power from battery packs.
• So they don't produce any emission of wasteage gas and they are eco friendly.
• They also have their own limitations such as range of coverage, temperature etc.
• An example for pure EV is Nissan Leaf.

Pure Electric Vehicle Reference block:

Now comparing both the pure electric and hybird electric vehicle with the given conditions in a simulation to observe the behaviour of both the type.

Case 1

Simulation condition :

The simulation is done for pure electric vehicle and Hybird electric vehicle with Wide Open Throttle (WOT) drive cycle.

The total cycle time = 100 seconds

The top speed of this cycle = 80 mph

Time to start deceleration = 50 seconds

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 accleration time to reach the top speed of 108.9 mph is 50 seconds

The deceleration time from maximum mph to minimum is 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 cycles.

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 from the battery = -173.7 A

Plot 5 :

Shows the Battery state of charge SOC(%) and its changes for correspomding 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 Fuel Economy as Miles 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 = 20.45 Miles , for the given vehicle at the specified driving conditions.

Case 2

Simulation condition :

The simulation is done for pure electric vehicle and Hybird electric vehicle with Wide Open Throttle (WOT) drive cycle.

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 run maximum speed of upto 58.9 mph

The accleration time to reach the top speed of 58.9 mph is 48.9 seconds

The deceleration time from maximum mph to minimum is 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 cycles.

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 = 225.8A

The peak current charging from the battery = -163.7 A

Plot 5 :

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

The state of charge decreased from 80% to 75.5% of charge in a time period of49 seconds, for the specified driving conditions.

Plot 6 :

Shows the Fuel Economy as Miles 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.

Observation :

• The electric vehicle when compared with hybird electric vehicle with the same environmental and drive conditions results in less top speed achievement.
• The electric vehicle produces more values of Motor speed and Motor Torque compared to the hybird vehicle's motor alone ,but hybird vehicle when it combines the torque of both motor and its engine is higher than the electric vehicle's torque.
• This is responsible to pull the hybird car at higher top speed compared to the pure electric.
• As the pure electric car here uses Lithium-ion battery compared to the Nickel-metal hydride battery the discharging capacity and the rate of charging is higher in the pure electric car.
• As it is able to discharge in a fast rate the motor can produce high amount of torque instantly compared to the hybird vehicle.
• Also the the state of charge shows the battery efficiency of the pure electric to be higher than the hybird vehicle and this is also due to the battery type used in these cars.
• The efficiency of the Electric car is higher than the hybird car which is evident from the miles per gallon numbers of both of these cars.
• Electric vehicle produces zero emissions whereas the hybird one produces waste gas emission.These are some of the observations from the comparision of the above simulations using Powetrain Blockset.