Project 1

Drive Cycles:

A driving cycle is a series of data points representing the speed of a vehicle versus time. Driving cycles are produced by different countries and organizations to assess the performance of vehicles in various ways, as for instance fuel consumption, electric vehicle autonomy and polluting emissions. Fuel consumption and emission tests are performed on chassis dynamometers. Tailpipe emissions are collected and measured to indicate the performance of the vehicle.

Another use for driving cycles is in vehicle simulations. More specifically, they are used in propulsion system simulations to predict performance of internal combustion engines, transmissions, electric drive systems, batteries, fuel cell systems, and similar components. Some driving cycles are derived theoretically, as it is preferred in the European Union, whereas others are direct measurements of a driving pattern deemed representative.

Most commom drive cycles:

• WLTC
• NEDC
• SORDS
• FTP-75
• UDDS
• HWFET

UDDS:

UDDS stands for Urban Dynamometer Driving Schedule, and refers to a United States Environmental Protection Agency mandated dynamometer test on fuel economy that represents city driving conditions which is used for light duty vehicle testing. It is also known as U.S. FTP-72 (Federal Test Procedure) cycle, LA-4 cycle, in Sweden as A10 or CVS (Constant Volume Sampler) cycle and in Australia as the ADR 27 (Australian Design Rules) cycle.

Though it was originally created as a reference point for fossil fueled vehicles, it is also used to give estimates on how many miles an electric vehicle will travel on a single charge.

HWFET:

The Highway Fuel Economy Test (HWFET or HFET) cycle is a chassis dynamometer driving schedule developed by the US EPA for the determination of fuel economy of light duty vehicles. The HWFET is used to determine the highway fuel economy rating, while the city rating is based on the FTP-75 test.

Code:

The below code is to determine the variable which is extracted from the simulink model using 'to workspace' command and also for plotting the desired values. We can change the drive cycle to get a result for various drive cycle by using the same code.

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]
Eng_Fuel_rate = out.Eng_Fuel_Rate;
Wheel_Speed = out.Wheel_Speed;


%% 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] 
kmpl1 = Veh_Dist./(Eng_Fuel_Consump/1000/rho_petrol);    % Fuel economy [kmpl] 

%% Plotting vehicle characteristics time trace
figure(1)
subplot(3,1,1)
title('For UDDS drive')
hold on
grid on
plot(Time, Acc_Pdl, 'linewidth', 1, 'Color', 'blue');
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', 'blue');
plot(Time, Trans_Out_Spd, 'linewidth', 1, 'Color', 'red');
ylabel('Speed [rpm]')
xlim([0, Time(end)]);
title('For UDDS drive')
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');
title('For UDDS drive')

%% 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',1,'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]  for UDDS Drive');
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)]);

figure(3)
hold on
plot(Veh_Dist,kmpl1)
xlabel('Distance in Km')
ylabel('Fuel consumption in L')
title('Fuel consumption for UDDS')

disp('            Fuel economy numbers')
disp('           ********************')
disp('Drive cycle                 kmpl')
fprintf('\n')
fprintf('UDDS                   %d\n',kmpl)
%fprintf('HWFET                 %d\n',kmpl2)

figure(4)
subplot(4,1,1)
title('For UDDS drive')
hold on
grid on
plot(Time,Eng_Pwr, 'linewidth', 1, 'Color', 'blue');
xlabel('Time')
ylabel('KW')
xlim([0, Time(end)]);
legend('Power');
subplot(4,1,2)
hold on
grid on
plot(Time, Eng_Trq, 'linewidth', 1, 'Color', 'red');
xlabel('Time')
ylabel('Nm')
xlim([0, Time(end)]);
legend('Torque');
subplot(4,1,3)
hold on
grid on
plot(Time, Eng_Fuel_Consump, 'linewidth', 1, 'Color', 'blue');
xlabel('Time')
ylabel('g')
xlim([0, Time(end)]);
legend('Fuel Consumption');
subplot(4,1,4)
hold on
grid on
plot(Time, Eng_Fuel_rate, 'linewidth', 1, 'Color', 'red');
xlabel('Time')
ylabel('g')
xlim([0, Time(end)]);
legend('Engine Fuel Rate');

figure(5)
subplot(3,1,1)
title('For UDDS drive')
hold on
grid on
plot(Time,Trans_In_Spd, 'linewidth', 1, 'Color', 'blue');
xlabel('Time')
ylabel('Rpm')
xlim([0, Time(end)]);
legend('Input Transmission ');
subplot(3,1,2)
hold on
grid on
plot(Time, Trans_Out_Spd, 'linewidth', 1, 'Color', 'red');
xlabel('Time')
ylabel('Rpm')
xlim([0, Time(end)]);
legend('Output Transmission');
subplot(3,1,3)
hold on
grid on
plot(Time, Wheel_Speed, 'linewidth', 1, 'Color', 'g');
xlabel('Time')
ylabel('m/min')
xlim([0, Time(end)]);
legend('Wheel Speed');

Code for define vehicle parameter and driver selection

%% 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 = 2;     % 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 :

Vehicle model

The vehicle has a three major blocks which is driver , controller and power train. In this project we focus on power train block that incles of Engine, Tranmission, Differencial, Wheels and vehicle dynamics.

The power train model for simulink shown above, it has five major blocks but we only focus on Engine and vehicle dynamics blocks only. The engine block is given below

The engine has a input as engine speed and engine torque. By using the data points which is already provided the lookup table formed to get a output of fuel rate,fuel consumption and engine torque. By using saturation block we can set a limit for the input from lookup table.

Lookup table

The output for fuel rate get from the saturation block. By integrating the value we can get fuel consumption values. And these values were stored in matlab workspace by using 'To workspace' command.

The above block repesent the vehicle dynamics block which is basically to calculate the vehicle acceleration, velocity and distance. The vehicle acceleration calculated from the sum of tractive force and total resistance force. The resistance force consists of Rolling, Grade and aerodynamic resistance. The below graph show how these resistance act on a vehicle

The parameters which stored in matlab workspace is shown below:

Result

The fuel economy numbers (kmpl) for UDDS and HWFET cycle.

Plots:

The time trace for engine, transmission input, transmission output and wheel speed.

For UDDS cycle

For HWFET cycle

• The above plots were plotted for transmission input,transmission output and wheel speed with respect to time for both UDDS and HWFET drive cycles.
• The input transmission got from the engine and it varies depend on the driver input, but here by using UDDS drive cycle the inputs were already defined.
• So the input transmission plot shows how the input goes.
• Then the output transmission and wheel speed act depend upon the input transmission.
• We can see that the wheel speed and output transmission curves were goes same to each other, because that two variables were react same as each other.

Engine torque,power and fuel rate,consumption plots

For UDDS drive cycle

For HWFET drive cycle

• The above plot shows the Engine power,engine torque,fuel rate and fuel consumption curves over time.
• We can see that the power and torque curves goes like same because these two factors dependes on each other.
• The other two curves represent the engine fuel consumption and engine fuel rate values.
• The fuel consumption and fuel rate is in grams as y axis.
• The fuel consumption shows the over all fuel consume over the time period.
• The fuel rate shows the fuel coumption of an engine at the particular time, so it varies over the time period.

Plot for accelerator and break pedal,gear command,vehicle desired and actual speed

For UDDS drive cycle

For HWFET drive cycle

• The above plot consists of three plots which is accelerator and brake pedal, vehicle desired and actual speed and gear command
• The first plot has two curves, the blue one reperesent accelerator behavior and the red one reperesant the breake behavior.
• When the brake curve raises the accelerator cuves goes down which shows these two curves inversly proposnal.
• The second curve shows the vehicle desired and actual speed.
• The input transmission goes quick vertical manner becaues it get from the user but the output won't, because it depends on the vehicle behavier.
• The third plot shows the gear command from the user.
• The lower gear basically has high torque and low power which means it can pull heavy weigh but it can't go high speed.
• But similarly the higher gear has low torque and high power.

Plot for engine operating points on engine fuel map

For UDDS drive cycle

For HWFET drive cycle

• The above map build by using contour command.
• The contour command basically has the inputs, it has x,y and z axis.
• The z axis is a 3D plot which shows top view of the plot we can also say that cross section view.
• The red line reperesent the maximum torque curve.
• The dotted lines reperesent the engine operating points where the engine operates randomly.
• The z axis which used here is engine fuel map.

Conclution:

The above report is basically to explain the engine behavior over the time period with various operating conditions. And the Drive cycles are the standard operating condition which helps to analyse the engine performance. Every engine manufactureres used these drive cycles to analyze engine performance which helps them to know how the engine produce output.