Week-4 Challenge WOT Condition Part-2

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

Ans.:

MAPPED ENGINE MODEL	DYNAMIC ENGINE MODEL
The model uses a set of steady -state lookup tables to characterise engine performance	The model decomposes the engine behaviour into engine characteristics that are seperated into lower level components, by combining the condonements in this way the model captures the dynamic effect entirely.
The table provides overall engine characteristics including the actual torque, fuel flow rate ,BFSC,and engine -out exhaust emissions.	We use this model in order to obtain a dynamic model and have component -level data.
We use this model ,if we have a engine data from a dynamometer or design -tool like GT-POWER. We also use this model for quisi-steady-state engine simulations.	It is used mainly to analyse the impact individual engine components on the overall performance.

MAPPED MODEL	DYNAMIC MODEL
The mapped motor block implements a mapped motor and drive electronics operating in torque-control mode.	It contains an interior PM model ,three phase voltage source inverter and internal permanent magnet synchronous machine (PMSM). All these combinations gives an EV dynamic.
The output torque tracks the torque reference demand and include a motor response and drive response constant. The Maximum power, maximum torque, and time control along with the constant needs to be given. Here ,electric losses needs to be specified present.	The parameters if motor ,current, electrical etc.are given.

• Step by step process is below with help of figures.
• Changing Model type: Steps

1. Open the EV_referance_application simulink model,where the model contains drive cycle,driver, environment conditions,controller and passenger cars. for getting the results, ope the visualisation option(as in Fig.1).

2.Open the Passenger car subsystem and it contains the drivetrain, electrical inputs and output blocks(as in Fig.2).

3. Open the electric plant which contains motor ,battery and other calculation block (as on fig.3)

4.Open Motor block, containing both mapped and dynamic block system (as in fig.4)

5.By default, mapped motor is Active.

6.To change the mapped to dynamic blackest, we need to right click on screen and select the variant option( as in fig.5).

7.Then,select the label mode activate choice and select Mot_Gen_ EV_Dynamic(as in fig.6).

Step by step process is below with help of figures.

Fig.1

Fig.2

Fig.3

Fig.4

Fig.5

Fig.6

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

Ans.: Calculation of battery power and vehicle speed in miles/gallon is used to find how much economical is the battery in comparison with the engine fuel consumption. The miles/gallon is equal to energy generated by electric power. It helps us to understand the economy of both vehicles.

• The block diagram represents the powertrain block set of EV vehicle to calculate the miles/gallon, where the given parameter are fuel flow, vehicle speed and batty power to find the fuel efficiency of the vehicle.
• Distance is calculated by integrating the vehicle speed with respect to time and converted to miles.
• Battey power is consumed by which the total distance is covered and converted from watt to kilowatt.
• The volume flow rate of the fuel is expressed and converted to gallons and integrated with respect to time for calculating the fuel volume.

So miles/gallon is calculated for the performance of the fuel economy of the car or commercial vehicle. Means if your car performs at 50mpg, that means you will be able to drive 50 miles on every gallon of petrol that you put in the tank.

FACTORS TO BE CONSIDERED FOR THE MODEL FUEL FLOW:

• The energy content of the fuel type to be considered.
• Th availability of the type of fuel source wanted .
• The cost of acquiring and using the fuel for each specific situation.
• How safe it will be to use the fuel under consideration.
• Vehicle speed.

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

The hybrid electric vehicle reference application represents a full multimode Hybrid electric vehicle(HEV) model with an internal combustion engine,transmission,battery,motor,generator,and associated powertrain control algorithms. Use the reference application for powertrain matching analysis and component selection, control, and diagnostic algorithm design, and hardware -in-the-loop(HIL) testing.

By default, The HEV multimode reference application is configured with:

• Mapped Motor and Generator
• 5-L spark-ignition(SI) dynamic engine.

The Diagram Shows Powertrain Configuration:

Steps:

• Open the HEV_referance_application with Wide Open Throttle(WOT) Drive cycle for a time interval of 50 sec. in which model is selected from the MATLAB help file.
• Within the model ,it has environment subsystem block, Drive cycle source block, longitudinal Driver sub system block, vehicle controller subsystem, passenger car sub system and visualization sub system block.
• The Grade and wind velocity to be changed is present in environment sub system block .
• Inside environment sub system block ,it has temperature, wind pressure, gradeability and wind velocity measurement system.

Condition 1:

Here we have changed Drive cycle to WOT condition with sample time 50sec.Gradeability and wind velocity kept as it is i.e.

WOT with simulation time=50 sec.

Gradeability=0,Wind Velocity=0

Result:

PLOT OBSERVATIONS:

• Trace Velocity:Target and actual velocity(mph) plot,th drive cycle used is WOT where the speed data input is given as a step signal of a magnitude of 110 mph approx. for a time of 30 sec. and become deaccelrate to 0 mph at 30 sec. Here the Trace velocity increases steeply from 0 at t=1 sec to 100 mph at 30 sec. and then decreases to 0 mph at 35.8 sec. Here it is observed that the actual velocity is not matched with target velocity mainly because of the limitations of the battery capacity and IC engine initial torque to propel the vehicle.
• Battery Current(A) plot:It is observed that the maximum battery capacity is about 520mph approx.which makes the abttery to provide more torque at the initial phase to IC engines.
• For the Engine Torque,Motor Torque and generator Torque(N-m):uring Braking it observed that motor speed and torque is slumped but the engine torque remain same.The motor torque and battery values are dropped to negative values including regenerative braking process happening in HEV vehicle.
• Battery SOC : It is observed that BMS in HEV vehicle is designed in such a way that battery SOC does not go below 66.48% after ehich the battery gets charge through either IC engine or plug in.
• Fuel economy(in MPG): shows miles/gallon equivalent to run the vehicle ,whwre the fuel need is high as vehicle speed is high and fuel requirement decreases as the vehicle deaccelerates.

Condition 2:

WOT with simulation time=50 sec and Gradeabiity = 5% and Wind velocity= 10m/s

Result:

PLOT OBSERVATION:

• When compared with previous results Trace velocity plot ,the actual velocity (mph) has drastically decreased from 110mph to 73 mph at 30 sec., due to change in gradeability and wind velocity from 0 to 5and 10 respectively.
• The Fuel efficiency has also dropped significantly ,as compared to previous results in US fuel economy (in MPG) block.
• The rest of the plot parameters are the same.

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

Ans.: Here, the two models : Hybrid and pure electric powertrain are compared by keeping all the parameters same .

• For HEV: Gradeability and wind velocity=0, Drive cycle= WOT, Total cycle time=50 sec., Top speed of vehicle= 50 mph, Time to start deacceleration=30 sec.
• For EV: in EV , there is no IC engine, no separate motor and generator because in EV motor itself function as generator during regenerative braking mode. Hence one set of gear is sufficient for EV rather than in HEV.

The following EV model autoblkEvStart is selected.

Result:

PLOT OBSERVATION and COMPARISON :

• For the Trace Velocity: Target and actual velocity(mph) plot, the graph seems almost similar to that of HEV model, which is mainly because of the maximum discharge limit from the battery ,which is 200 A.
• For Motor Speed(rpm): As Battery and the Motor are only driving units of this EV ,then maximum motor speed (rpm)is approximately 1000rpm which is less than maximum motor speed of the HEV vehicle which was 12200rpm approx..
• For Motor Torque(N-m): the motor torque at initial level of an EV about 280 N-m is less than that of HEV ( approx. 300 N-m) as the weight of EV is lesser than HEV.
• Here the fuel economy is higher in EV than as compared to with HEV.
• The pure EV drive achieves less top speed as compared to HEV.
• Instantaneous torque at Start is mor in EV as compared with HEV.
• The conventional HEV uses Lead acid battery whereas pure EV uses Lithium Iron Batty which is more potential.

Here the observation and result of simulation of HEV with WOT drive cycle time=50 sec., the top speed =50mph, and time to start deacceleration =30sec and keeping all parameter same (Gradeability and wind velocity=0) is given with necessary figures.