Project 1
Project 1 deals with the development of a forward energy-based fuel consumption model of a conventional vehicle.
The main goal of this project is to get familiar with the modeling process, writing scripts in Matlab, modeling in Simulink, analyzing data and generating plots.
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.
“Project1_VehicleModel.slx” is the Simulink model of the vehicle. 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 vehicle speeds. 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
Converter’. The output of the transmission is connected to the ’Differential’, which powers the ‘Wheels’, that provides the tractive force for vehicle acceleration. The longitudinal dynamics of the vehicle along with the road load is represented in the ‘Vehicle Dynamics’ block. The solver selected is ode3 with a fixed step size of 0.01 sec.
After running this Simulink model, data from the model will be loaded in the Matlab workspace.
“Project1_ProcessingFile.m” is the Matlab script used to analyze this data and to generate plots. This script needs to be executed after the Simulink model data has been loaded into the workspace. Here we
rename the variables loaded from the model (if desired), do some basic post-process calculations and generate results and plots.
Task:
The task of this project is to compute the fuel economy numbers for the given vehicle (kmpl) on the urban cycle (UDDS) and highway cycle (HWFET). Also, to analyze and understand the vehicle operating
points in terms of engine speed, torque, transmission speeds, pedal positions, gear, distance traveled, etc.
To do that, the following steps need to be followed:
1) Load the Project1 folder as the Current Folder in Matlab.
2) Run the “Project1_InitFile.m” Matlab script.
3) The provided vehicle Simulink model “Project1_VehicleModel.slx” is incomplete. The engine and vehicle dynamics block contents have been deleted. Build the Simulink blocks by referring to the course lecture and example block imag
es provided. You can run the model and analyze the results using a ‘Scope’ for debugging.
4) Add additional ‘To Workspace’ blocks for transferring the desired Simulink vehicle data into the Matlab workspace.
5) Modify the “Project1_ProcessingFile.m” as per the desired plots and required calculations.
6) Write a project report that contains the following:
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.
Answer:-
For the UDDS Drive Cycle
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Skill-Lync -> Hybrid Drives Development
% Project 1 - Conventional Vehicle Model
% By - Prafful Keshav Sadavarte
% 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;u1
end
time_end = cyc_time(end);
vel_end = cyc_vel(end);For HWFET Drive Cycle
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Skill-Lync -> Hybrid Drives Development
% Project 1 - Conventional Vehicle Model
% By - Prafful Keshav Sadavarte
% 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 = 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;u1
end
time_end = cyc_time(end);
vel_end = cyc_vel(end);Following is a detailed explanation of a forward energy-based fuel consumption model of a conventional vehicle.
conventional vehicle
Conventional vehicles use an internal combustion engine fueled by gasoline or diesel to power the wheels. Electricity is used for some accessories but is not used to move the vehicle.
Mainly it consists of three blocks
1. Driver block
2. Controller block
3. Powertrain
1. Driver block
Driver Model is a basic PI controller that generates accelerator and brake pedal outputs to match the desired and actual vehicle speeds. The PI controller controls the error between the required drive cycle and actual vehicle speed by providing acceleration and brake pedal output to the controller.
Scope output in Driver Block:-
For the UDDS Cycle
For the HWFET Cycle
2. Controller block
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
The controller consists of an engine control unit, a transmission control unit, and a brake control unit.
All control signals can be scoped.
The controller consists of three block
1. Engine Control Unit
2. Transmission Control Unit
3. Brake Control Unit
Scope output in controller Block:-
For the UDDS Cycle
For the HWFET Cycle
1. Engine Control Unit
The engine Controller consists of one block
1-1. Ideal Speed controller
1-1. Ideal Speed controller
Engine Control Unit Compare engine speed with the maximum torque and minimum torque curves of the lookup table and give the required torque command to the engine block. The throttle input is combined with the idle speed throttle and gains with the torque output from the lookup table to estimate the torque input required for the engine. Throttle input, idle throttle, and their sum can be scoped from this block.
Scope output in engine control unit Block:-
For the UDDS Cycle
For the HWFET Cycle
2. Transmission Control Unit
The Gear shifting is Controlled according to the vehicle speed and throttle input.
The gear command is passed to the Transmission block to select the desired gear ratio.
The transmission control block controls the gear shifting using the study flow Variable chart.
3. Brake Control Unit
- Brake Control unit Produce required brake torque according to the brake pedal input and passes the brake torque in to the wheel block in the transmission model.
3. Powertrain Model
- The powertrain model includes all the components that convert the power of the engine into vehicle motion.
Powertrainconsist of following block
1.Engine block
2.Transmission block
3.Differential block
4.Wheels block
5.vehicle dynamics block
1.Engine block
- Based on the Engine speed The required torque from the controller is saturated between Max torque curve and min torque curve and passes the Engine torque to the Transmission block
- The 2D lookup table is used to calculate the fuel flow rate based on engine speed and engine torque. The fuel flow rate is then integrated to find the fuel consumption.
- Estimated fuel flow rate, fuel consumption, engine torque and engine speed are passed to the MATLAB workspace using the to-workspace block.
- Engine fuel flow rate and Fuel consumption are scoped.
Scope output for Engine Torque
For the UDDS Cycle.
For the HWFET Cycle
2.Transmission block
- The engine block is connected to the automatic transmission via a torque converter. The output of the transmission is connected to the differential.
Scope output Transmission blockl:- 1] Transmission in speed 2] Gear ratio 3] Differential Ratio
For the UDDS Cycle
For the HWFET Cycle
Torque Converter
- The gear selection from the transmission control unit is multiplied by the engine torque in this block, and the efficiency and engine dynamics of the torque converter are applied in this model.
Scopes output in the Torque converter
For the UDDS Cycle.
For the HWFET Cycle.
3.Differential block
- The transmission output torque is multiplied by the differential ratio and differential efficiency in this block and the torque is transmitted to the wheel as the axle torque.
4.Wheels block
- The brake torque from the control model is subtracted from the Axle torque and divides from the rolling radius to determine the Tractive force.
- The Wheel speed is calculated from the vehicle velocity and saved in the workspace.
5.vehicle dynamics block
- The longitudinal dynamics of the vehicle along with the road load is represented in the ‘Vehicle Dynamics’ block
- Tractive Force and Road loads are used to calculate the vehicle velocity
Scope output for Vehicle Dynamics
For the UDDS Cycle.
For the HWFET Cycle.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Skill-Lync -> Hybrid Drives Development
% Project 1 - Conventional Vehicle Model
% By - Prafful Keshav Sadavarte
% 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]
WheelSpd = out.WheelSpd;
Eng_Fuel_Rate = out.Eng_Fuel_Rate;
%% 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]
%% b. Plot the time trace for engine, transmission input, transmission output and wheel speed on one plot.
figure(1)
hold on
grid on
plot(Time, Trans_In_Spd, 'linewidth', 1, 'Color', 'black');
plot(Time, Trans_Out_Spd, 'linewidth', 1, 'Color', 'red');
plot(Time, WheelSpd,'Color', 'blue');
ylabel('Speed [rpm]')
xlim([0, Time(end)]);
ylim([0, 6000]);
legend('Trans Input','Trans Output','WheelSpd');
%% c. Plot engine torque, engine power, fuel rate and fuel consumption using subplots.
figure(2)
subplot(2,2,1)
plot(Time,Eng_Trq,'LineWidth',1,'Color','black')
hold on
grid on
title('Time Vs Engine Torque')
xlabel('Time [S]')
ylabel('Engine Torque')
subplot(2,2,2)
plot(Time,Eng_Pwr,'LineWidth',1,'Color','red')
hold on
grid on
title('Time Vs Engine Power')
xlabel('Time [S]')
ylabel('Engine Power')
subplot(2,2,3)
plot(Time,Eng_Fuel_Rate,'LineWidth',1,'Color','blue')
hold on
grid on
title('Time Vs Engine Fuel Rate')
xlabel('Time [S]')
ylabel('Engine Fuel Rate')
subplot(2,2,4)
plot(Time,Eng_Fuel_Consump,'LineWidth',1,'Color','green')
hold on
grid on
title('Time Vs Engine Fuel Consumption')
xlabel('Time [S]')
ylabel('Engine Fuel Consumption')
%% Plot fuel rate and fuel consumption using subplots
figure(3)
plot(Eng_Fuel_Consump,Eng_Fuel_Rate)
title('Engine Fuel Rate Vs Engine Fuel Consumption')
xlabel('Engine Fuel Rate')
ylabel('Engine Fuel Consumption')
%% d. Plot accelerator and brake pedal, gear command, vehicle desired and actual speed, vehicle distance using subplots.
figure(4)
subplot(4,1,1)
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(4,1,2)
hold on
grid on
plot(Time, Gear_Cmd, 'linewidth', 1, 'Color', 'black');
xlim([0, Time(end)]);
xlabel('Time [s]');
ylabel('Gear');
subplot(4,1,3)
plot(Veh_Spd,Gear_Cmd)
xlabel('Vehicle Speed');
ylabel('Gear Command');
subplot(4,1,4)
plot(Veh_Dist,Gear_Cmd)
xlabel('Vehicle Distance');
ylabel('Gear Command');
%% 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)]);
a. Tabulate the fuel economy numbers (kmpl) for UDDS and HWFET cycles. This forms the baseline numbers for comparison with the future hybrid version.
The fuel economy number (kmpl) for the UDDS cycle is 18.1822
The fuel economy number (kmpl) for the HWFET cycle is 21.8170
b. Plot the time trace for the engine, transmission input, transmission output, and wheel speed on one plot.
For The UDDS cycle
For The HWFET cycle
c. Plot engine torque, engine power, fuel rate and fuel consumption using subplots.
For The UDDS cycle
For The HWFET cycle
d. Plot accelerator and brake pedal, gear command, vehicle desired and actual speed, vehicle distance using subplots.
For The UDDS cycle
For The HWFET cycle
e. Plot the engine operating points on the engine fuel map.
For The UDDS cycle
For The HWFET cycle
Conclusion:- As compared to UDDS the more efficient cycle is HWFET because the Fuel economy number is higher, and there are fewer variations in the Acceleration padel, Break padel, gear command, vehicle speed, Transmission input Speed, Transmission output Speed, And Wheel speed