Project 1
TITLE:Project 1:
Deals with the development of a forward energy-based fuel consumption model of a conventional vehicle.
AIM:
a. Tabulate the fuel economy numbers (kmpl) for UDDS and HWFET cycle. This forms the baseline numbers for comparing with the future hybrid version.
b. Plot the time trace for engine, transmission input, transmission output and wheel speed on one plot.
c. Plot engine torque, engine power, fuel rate and fuel consumption using subplots.
d. Plot accelerator and brake pedal, gear command, vehicle desired and actual speed, vehicle distance using subplots.
e. Plot the engine operating points on the engine fuel map.
f. Write down appropriate brief comments on each of these plots, describing the vehicle behavior throughout the drive cycle.
g. Generate the plots for both drive cycles.
Conventional vehicle: the vehicvle which completly run on IC engine , its convert the chemicle energy of fuel in mechanical energy by burningthe fuel that is combustion process thats called conventional vehicle.
Energy and performance of vehicle:power coming from power train dictates the power demand on wheel as per performance ,acceleration ,speed etc determined by it.
Conventional powertrain efficiency:in Conventional vehicle convert the chemicle energy of fuel in mechanical energy by burning the fuel that is combustion process .this burning fuel have a certain amount of efficiency.
INSTANTANIOUS FUEL CONSUMPTION CALCULATED AS:
mf=Pe/nt*ne*Qlhv
where,
mf =mass pf fuel
nt=efficiency of
ne=efficiency of engine.
Qlhv= calorific or lower heating value of fuel.
Pe=power of engine.
SYSTEM DYANAMICS:
It include following content.
Effort:it generalised force variable ex. torque,force ,voltage,heating value.
Flow: it generalised velocity variable ex. velocity,curent,mass flow rate
Power: it product of above two variable. it interchangeable between energy domain.
ENERGY BASED MODEL:
MAP MODEL: its create by making relation between input and output ,output and losses.
ANALYTICAL MODEL: its making physical model that represent internal dynamics.
In this model we use forward model:
Its also called as dynamic simulation,in this dynamic simulation are used for detailed simulaion . in this model input variable are force/torque/power and output are vehicle state variable velocity and accelersation are output also there is feedback loop for meet the desired vehicle state ,its mainly used the vehicle driving cycle to analyse the dynamic behaviour of the system help significanly on control the development.
MATLAB SCRIPT:
%% Skill-Lync -> Hybrid Drives Development
% Project 1 - Conventional Vehicle Model
% By - SHIRSHAK JADHAO
% Description:
%% Initialization File
% Initialization file for loading the variables for the Conventional vehicle simulation model
%% Vehicle Parameters
M = 1500; % Vehicle weight [kg]
Cr = 0.015; % Rolling resistance coefficient
Rw = 0.35; % Rolling radius [m]
Cd = 0.33; % Drag coefficient
Af = 2; % Frontal area [m2]
rhoa = 1.225; % Air density [kg/m3]
Vwind = 0; % Wind velocity [kmph]
g = 9.81; % Gravitational acceleration [m/s2]
theta = 0; % Slope [deg]
myu_road_tire = 1; % Coefficient of friction between tire - road interface
%% Powertrain Parameters
FDR = 3.73; % Final Drive Ratio / Diff Ratio
DiffEff = 0.99; % Differential efficiency (assumed independent of operating conditions)
NumGear = 4; % Number of gears in transmission
TransGear = [1:NumGear]; % Transmission Gears
TransRatio = [3.06, 1.62, 1, 0.7]; % Corresponding Transmission ratios
TransEff = 0.90; % Transmission efficiency (assumed independent of operating conditions)
TC_SR = [0, .5, .6, .7, .8, .87, .92, .94, .96, .97, 1]; % Torque Converter Speed Ratio (Matlab default) -> TurbSpd/PumpSpd
TC_TR = [2.232, 1.5462, 1.4058, 1.2746, 1.1528, 1.0732, 1.0192, 1, 1, 1, 1]; % Torque Converter Torque Ratio (Matlab default) -> TurbTrq/PumpTrq
TC_Cf = 1e-4 * [.72558, .66322, .63463, .59042, .51331, .4144, .29287, .22444, .12186, .04386, 0]; % Torque Converter Capacity Factor (Matlab default) -> PumpTrq/PumpSpd^2 [Nm/rpm^2]
load Vehicle_Data/Engine_data_1_9L_Saturn_95kW
load Vehicle_Data/Trans_Shift_map
%% Driver Parameters
Kp = 10; % P gain for driver PI model
Ki = 1; % I gain for driver PI model
Drive_Cycle_Select = 1; % Drive cycle selection
% Drive cycle values in m/s
if Drive_Cycle_Select == 1
load DriveCycles/UDDS;
elseif Drive_Cycle_Select == 2
load DriveCycles/HWFET;
elseif Drive_Cycle_Select == 3
load DriveCycles/FTP;
elseif Drive_Cycle_Select == 4
load DriveCycles/US06;
elseif Drive_Cycle_Select == 5
load DriveCycles/NEDC;
elseif Drive_Cycle_Select == 6
load DriveCycles/WLTP;
end
time_end = cyc_time(end);
vel_end = cyc_vel(end);SIMULINK MODEL FOR CONVENTIONAL VEHICLE:
In this project, a typical midsize car with a 1.9L engine and a 4-speed automatic transmission is considered. Data is taken from ADVISOR data base developed by NREL, USA. Transmission shift map and controller is taken from Matlab/Simulink example database.
The model developed has the capability to simulate the vehicle on different drive cycles like UDDS, HWFET, FTP, NEDC, etc.
“Project1_InitFile.m” is a Matlab script used to load all the variables required for running the Simulink model and for post-processing. The drive cycle selection is also done here. Before running the Simulink
vehicle model, run this initialization script.
DRIVER BLOCK:
It is modeled using a ‘Driver’ block, which is a basic PI controller that generates accelerator and brake pedal outputs to match the desired and actual desired speed in that use drive cycle fro on the basis result of fuel consumption and emmision so vehicle get certified.its based on time,velocity then all integrate and create output acceleration pedal and brake pedal.
Gaph created from scope in driver model:
- CONTROL MODEL: The ‘Controller’ block is the brains of the vehicle, representing the electronic controls units. Based on the driver inputs, it generates desired engine torque, desired transmission gear,and desired brake torque. These inputs are fed to the ‘Powertrain’ block which represents the drivetrain of the vehicle. It consists of an ‘Engine’ connected to the ‘Automatic Transmission’ through a ‘Torque.
1.ENGINE CONTROL UNIT MODEL: IN THIS WE giveengine speed as input by creating look up table. in that table we give input maximum torque and map speed then create second look up tabe in that give input as ct torque and map speed then its subtract and multiply.
GRAPH CREATED BY SCOPE IN DRIVER MODEL :
2.TRANSMISSION CONTROL UNIT MODEL: Im this we created steady flow variable state for controlling gear of vehicle as ascending as well as desending order with respect to time,speed,distance and give inout to steady state in vehicle speed.
3.BREAK CONTROOL UNIT: It calculated to brake torque and all three control output send to powertrain.
- POWERTRAIN:It consist Engine,transmission,differential,axles.
- ENGINE: In this model we used map based model to determine fuel consumption by engine,its based on maxima and minimum torque from the controller .then saturated torque and speed map give fuel consumption takes the speed and torque then output goes into saturated then its integrated.
Graph made by scope in driver model engine torque.:
2.TRANSMISSION: In this engine toque,gear selector from controler block for transmission gear ratio.the ratio speed multiply by transmission input torque and then transmission efficiency positive and negative torque gives transmission input speed, also torque converter is connected to engine to transmision.
Graph created by scope from driver model:1 transmission in speed. 2 Gear ratio. 3 differential ratio.
3.DIFFERENTIAL: In this transmission output is input then its going to differntial ratio multiplied the input and output torque then we meet the axial torque,this axial torque is lower than differntial rato and transmission torque.
4.WHEEL:
In this we take axial torque from differnrtial and brake torque from controller.subtracts and multiply rolling radius and velocity the we get tractive force from axle and brake torque,wheelspeed is meet using velocity variable.
5.VEHICLE DYNAMICS:
IT consist tractive firce and road load , it dictates the vehicle speed on the basis of tractive force and road load.below given the dynamic equation.
Meq=dVvehicle/dt=ntλtot*Tm/Rω -[(0.5p*A*Cd(Vveh + Vω ε d)^2+Cr*Mgcos(theta)+Mgsin(theta)]
where,
p=density
M=mass
Cd=coefficient of drag
A=frontal area
Cr=coefficent of rolling
Vvech=Velocity of vehicle
g=gravity
Vω=velocity of wind
then we calculate and integrate then we get accelertaion and velocity of vehicle that is vehicle speed and vehicle distance
Graph created from scope from driver model:1.road load 2.acceleration. 3.tractive force.
Graph created from scope from driver model:1.road load.
then we calculate the fuel economy no. using UDDDS and HWEFT Cycles:
1] UDDS Drive Cycle:
TIME VS SPEED: In this speed is incrasing contineously.
Aerodynamic Drag: in this Aerodynamic drag is dirctly propotional to power.
Rolling Resistance: it also increases as power increses. wrt time.
Total Power:Aerodynamic drag +Rolling resistance + inertial resistance.
Conclusion :Toatl power increses slowely as aerodynamic drag,rolling resistance and inertial resistance incerese.
HWFET DRIVE CYCLE :
Time VS Speed : Speed is contineously increses wrt time.
Aerodynamic Drag: Drag is increses when power is increses.
Rolling Resistance :its decreses wrt time
Total Power:Aerodynamic drag +Rolling resistance + inertial resistance.
Conclusion :Toatl power increses slowely as aerodynamic drag and inertial resistance incerese ,but in this cycle bad impact occure due to decrasing rolling resistance.
Result: So as per above conclusion ,UDDS cycle prefered over the HWEFT cycle, its best asses the fuel consumption and pollution emmision of vehicle in normalised way.
Now for making plot ,matlab script as below:
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Skill-Lync -> Hybrid Drives Development
% Project 1 - Conventional Vehicle Model
% By- SHIRSHAK JADHAO
% Description:
% The following file is to used with the Initialization file and Simulink
% results for post-processing of the data.
% The file is incomplete, has some examples of how the data is imported
% into a readable format, data analysis and plotting examples.
% Based on the project task, use commands in a similar format as given
% below, to analyse the data and generate required plots.
% You can change variable names if desired
%% Post-Processing File
% File for post-processing the Conventional vehicle simulation model data
%% Renaming variables
Time = out.tout;
Acc_Pdl = out.Acc_Pdl; % Accelerator pedal [%]
Brk_Pdl = out.Brk_Pdl; % Brake pedal [%]
Gear_Cmd = out.Gear_Cmd; % Transmission gear
Trans_In_Spd = out.Trans_In_Spd*30/pi; % Transmission input speed [rpm]
Trans_Out_Spd = out.Trans_Out_Spd*30/pi;% Transmission output speed [rpm]
Eng_Trq = out.Eng_Trq; % Engine brake torque [Nm]
Eng_Spd = out.Eng_Spd*30/pi; % Engine speed [rpm]
Eng_Fuel_Consump = out.Eng_Fuel_Consumption; % Engine fuel consumption [g]
Veh_Dist = out.Veh_Dist/1000; % Distance traveled by vehicle [km]
Veh_Spd = out.Veh_Spd*18/5; % Vehicle speed [kmph]
%% Data Analysis
Eng_Pwr = Eng_Spd*pi/30*Eng_Trq/1000; % Engine brake power [kW]
rho_petrol = 0.7197; % Density of petrol [kg/L]
kmpl = Veh_Dist(end)/(Eng_Fuel_Consump(end)/1000/rho_petrol); % Fuel economy [kmpl]
%% Plotting vehicle characteristics time trace
figure()
subplot(3,1,1)
hold on
grid on
plot(Time, Acc_Pdl, 'linewidth', 1, 'Color', 'black');
plot(Time, Brk_Pdl, 'linewidth', 1, 'Color', 'red');
ylabel('Pedal [%]')
xlim([0, Time(end)]);
legend('Accel','Brake');
subplot(3,1,2)
hold on
grid on
plot(Time, Trans_In_Spd, 'linewidth', 1, 'Color', 'black');
plot(Time, Trans_Out_Spd, 'linewidth', 1, 'Color', 'red');
ylabel('Speed [rpm]')
xlim([0, Time(end)]);
ylim([0, 6000]);
legend('Trans Input','Trans Output');
subplot(3,1,3)
hold on
grid on
plot(Time, Gear_Cmd, 'linewidth', 1, 'Color', 'black');
xlim([0, Time(end)]);
xlabel('Time [s]');
ylabel('Gear');
%% Plotting engine operating points on engine fuel map
figure('Name','Engine Operating Points');
hold on
grid on
title('Engine Operating Points','fontsize',12);
p1=plot(Eng_map_spd*30/pi,Eng_max_trq,'linewidth',2,'color','r');
p2=line([Eng_map_spd(end)*30/pi Eng_map_spd(end)*30/pi],[0 Eng_max_trq(end)]);
set(p2,'linewidth',1,'linestyle','--','color','k');
p3=line([Eng_map_spd(1)*30/pi Eng_map_spd(1)*30/pi],[0 Eng_max_trq(1)]);
set(p3,'linewidth',1,'linestyle','--','color','k');
[c,h] = contour(Eng_map_spd'*30/pi,Eng_map_trq,Eng_fuel_map');
clabel(c,h);
xlabel('Engine Speed [rpm]');
ylabel('Engine Torque [Nm]');
title('Engine Fuel Consumption Map [g/s]');
p4 = plot(Eng_Spd,Eng_Trq,'.','color','k');
legend([p1 p4],{'Max Curve','Operating Points'});
axis([Eng_map_spd(1)*30/pi Eng_map_spd(end)*30/pi 0 Eng_map_trq(end)]);
- PLOTTING VEHICLE CHARACHTERISTIC TIME TRACE TRANSMISION IN /OUT AND WHEEL SPEEd:
In this transmission input and transmission output will fluctuate up and down as increasing time and speed.
- PLOTTING VEHICLE CHARACHTERISTIC TIME TRACE ,ENGINE SPEED ,TORQUE,POWER ,ENGINE FUEL RATE,ENGINE FUEL CONSUMPTION:
ENGINE TORQUE,POWER ,ENGINE FUEL RATE,ENGINE FUEL CONSUMPTION INCRASES WRT TIME.
- Plotting Fuel economy VS Fuel Consumption Plot: in this plot fuel economy is incerasing the fuel consumption alos increses and fuel economy is constant fuel consumption is also constant
- Plotting Accelerator pedal,brake pedal and gear command wrt time: In this brake of vehicle is minmum than acceleration of vehicle so ,brake torque is minimum required as gear shifting is required with resspect to time.
- Plotting gear command wrt vehicle actual speed: In this gearshifting is required as incrrase speed,shifting order is gear1,gear2,gear3,gear4.
Engine Operating Point:
- Engine fuel Consumption plot:
in this plot, decrase torque, increses speed.
