Project 1

Aim :-

1] Build Simulink model using blocks and complete the vehicle model.

2] Writting scripts in MATLAB to load all the variables required for running the Simulink model.

3] Tabulate the fuel economy numbers (kmpl) for UDDS and HWFET cycle.

4] Plot the time trace for engine, transmission input, transmission output and wheel speed on one plot.

5] Plot engine torque, engine power, fuel rate and fuel consumption using subplots.

6] Plot accelerator and brake pedal, gear command, vehicle desired and actual speed, vehicle distance using subplots.

7] Plot the engine operating points on the engine fuel map.

8] Generate the plots for both drive cycles.

9] Study of Conventional vehicle simulink model and creates graphs.

Conventional Vehicle:-

Conventional vehicles use an internal combustion engine fueled by gasoline or diesel to power the wheels. In this the heat engine uses the principle of heat release through combustion of a fuel with an oxidizer in a combustion chamber to create expanding gases which pushes against a piston creating forcce and torque output.

In this vehicle engine converts chemical energy stored in the fuel into heat which is used to produce useful work. Typically use fossil fuels like petroleum (petrol and diesel).

The most popular type of engine is used in this system is 4 stroke reciprocating engine. Engine in cyclinder process can be represented by ideal thermodynamic cycles such as Otto cycle, Diesel cycle. Otto cycle is a ideal cycle thet describes the cycle process for spark ignited SI engine. and the Diesel cycle is the ideal cycle thet describes the cycle process for a compression ignited CI engine.

Energy and performance of vehicle:-

In this system trge power demand on the wheel need to instant supplied by the powertrain. In otyher word the power coming from the powertrain dictates the power demand on the wheels (as per performance viz, acceleration, speed etc is determined by it.

In tis vehicle the powertrain is consists of an engine connected to the wheels through a transmission therefore the power comes from the engine through the transmission.

Conventional powwertrain efficiency:-

The engine generates power by converting chemical energy stored into the mechanical energy by the process of combustion. This process of energy conversion also has an efficiency and the energy input is in the form of fuel consumption.

- Instantaneous fuel consumption is given as

Where,

mf = mass flow rate in [kg]

pe = Power of engine

pt = power of transmission

nt = efficiency of transmission

ne = efficiency of engine

QLHV = it is th ecalorific value/ lower heating value of fuel.

In this system of IC engine if tge power at the wheels is zero the engine is idling and still consumes some fuel to overcome the engine drag loss and keep it spinning this is the idling fuel consumption and know as idling process. Above mentioned formula is applicable only when the wheel power is strictly power. When the wheel power is negative either th engine is disengaged and idling or the engiune is engaged and providing some engine braking due to the engine drag losses.

The engine is consuming fuel when it is idling but even for engine braking the engine might be consuming some fuel.

The fuel consumption not only depend on the power requirement at the wheels but also is required to generate power to run the various engine and vehicle accessory loads.

System Dynamics:-

It deals with the modeling of multi domain systems through the use of a unified approach based on a ordinary differential and algebraic equation describing the static and dynamic effects.

Each systems has are two generalised variables-

1] Efforts:- It is generalised force variable. ex- torque, force, voltage, heating value.

2] Flow:- It is the generalised flow/velocity variable. ex:- velocity, current, mass flow rate.

3] Power:- It is the product of the effort and flow variable. It is interchangeable between energy domains.

Energy based models- Element models

To models the internal physical properties of the element and the losses there are basically two kinds of approach.

1] Map based models:- Elements are modeled using maps which characterized the relationship between the input and output , output and losses etc.

2] Analytical models:- Elements are modeled using physical equation that represent the internal dynamics. These are the two extremes most models are a combination of the two with some dynamics models analytically and for some using maps.

In this model We use Forward Model:-

It also known as dynamic simulation. Dynamic models are used for detailed simulations. In this model force/torque/power is the input and the vehicle state variable velocity and acceleration are outputs. The models and simulatios are more realistic due to phhysical casualty hence appropriate for control development. There is feedback loop to meet the desired vehicle state. It is mainly used to simulate a vehicle on a driving cycle to analyse the dynamic behaviour of the system helps significantly in control development.

MATLAB scripts:-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.

%% Skill-Lync -> Hybrid Drives Development
% Project 1 - Conventional Vehicle Model
% By - Ullekh Gambhira

% 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);

Now,

lets see the simulink model of 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 Model:-

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. In this we use drive cycles fro the based on these results of fuel consumption and emissions the vehicle gets certified and it also forms a basis of uniform asessment. It is based on time, velocity then its all integrate and creates output accelration pedal and brake pedal.

Control Model:-

The ‘Controller’ block is the brains of the vehicle, representing the electronic controls units. It is 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.

1. Engine control Unit:-

creating look up table. in that table we give input Maximum torque and map speed then also create 2nd look up trable in that give input ct torque and map speed then it substracts and multiplied. the engine speed also give to ideal contro speed to integrate from this we meet output of engine required torque.

2. Transmission control unit :-

In this unit we create steadfy flow variable state for controlling of gears of vehicle as in ascending and descending order with respect to time, speed, distance. and give input to this steady state is vehicle speed in m/s to mph.

3. Brake Control Unit:-

In this calculate brake torque and then all three control signals output is give to powertrain.

3] PowerTrain:-

The powertrain encompasses every component that converts the engine's power into movement. This includes the engine, transmission, the driveshaft, differentials, axles; basically anything from the engine through to the rotating wheels.

1.Engine

In this model we used map based model to model the fuel consumption of engine. It is based on maximum Torque and minimum torque from the controller. and then it saturated torque and give output then saturated torque and speed map give fuel consumption takes the speed and torque then the output goes into saturated then its integrated.

2. Transmission:-

In these model we take engine torque, gear selector from controllerb for transmission of gear ratio. The ratio is multiply by transmission input torque and then the transmission efficiency positive torque and negative torque gives transmission input speed. In this case torque converter connects the engine to transmission it is part of transmission. In it basically engine dynamics and that is decoupled.

3. Differential :-

In this taking input is the transmission output then its going to the differential ratio multiplied the output and input torque then meet axle torque. The axle torque is a lower than the transmission torque and differential ratio.

4. Wheels :-

In this model we take the axle torque from differentail and brake torque from controller. it is substracts and multiplied rolling radius and velocity then we meet the tractive force from axle and brake torque. and the wheelspeed is meet using velocity.

5. Vehicle Dynamics :-

In this takes tractive force and road load. It is dictates vehicle speed based on tractive force and road load.

the dynamic equation for calculating road load is

MeqdVvehdt=ηtλtotRwTm-(12p⋅A⋅Cd⋅(Vveh+Vw∈d)2+Cr⋅M⋅g⋅cos(θ)+M⋅g⋅sin(θ))">MeqdVvehdt=ηtλtotRwTm−(12p⋅A⋅Cd⋅(Vveh+Vw∈d)2+Cr⋅M⋅g⋅cos(θ)+M⋅g⋅sin(θ))MeqdVvehdt=ηtλtotRwTm-(12p⋅A⋅Cd⋅(Vveh+Vw∈d)2+Cr⋅M⋅g⋅cos(θ)+M⋅g⋅sin(θ))

where,

p = air density [kg/m^3]

A = Frontal area [m^2]

Cd = drag Coefficiend

Vveh = velocity of vehicle [m/s^2]

Vwind = velocity of wind [m/s^2]

Cr = rolling resistance coefficient

M = mass in [Kg]

g = gravity.

Then we calculate and integrate then we meet acceleration of vehicle and velocity of vehicle it mean vehicle distance and vehicle speed.

SIMULATION RESULTS

1. UDDS Drive Cycle

Drive Cycle and Actual Velocity

Control Signals (Engine Torque, Transmission Gear and Brake torque)

Engine Fuel Rate and Fuel Consumption

Engine Torque

Gear Ratio, Transmission Input and Output Speed

Tractive Force, Road Load and Acceleration

2. HWFET Drive Cycle

Drive Cycle and Actual Velocity

Control Signals (Engine Torque, Transmission Gear and Brake torque)

Engine Torque

Engine Fuel Rate and Fuel Consumption

Gear Ratio, Transmission Input and Output Speed

Tractive Force, Road Load and Acceleration

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Skill-Lync -> Hybrid Drives Development
% Project 1 - Conventional Vehicle Model
% By - Gaurav Somase

% 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]
Wheel_Spd = out.Wheel_Spd*30/pi; %Wheel speed [Kmph]
Eng_Fuel_Rate = out.Eng_Fuel_Rate; %Engine Fuel rate (g/sec.)
Eng_Spd_1 = Eng_Spd.Data(:,1);
Eng_Trq_1 = Eng_Trq.Data(:,1);
%% 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)]);
%%
figure(3)
grid on
plot(Eng_Spd,'linewidth',1,'color','black');
hold on
plot(Wheel_Spd,'linewidth',1,'color','red');
hold on
plot(Time,Trans_In_Spd,'linewidth',1,'color','blue');
hold on
plot(Time,Trans_Out_Spd,'linewidth',1,'color','green');
ylabel('Speed [RPM]')
legend('Engine Speed','Wheel Speed','Transmision Input Speed','Transmission Output Speed')
%%
figure(4)
subplot(4,1,1)
grid on
plot(Eng_Trq,'linewidth',1,'color','blue');
ylabel('Engine Torque [NM]')

subplot(4,1,2)
grid on
plot(Eng_Pwr,'linewidth',1,'color','green')
ylabel('Engine Power [KW]')
subplot(4,1,3)
grid on
plot(Eng_Fuel_Rate,'linewidth',1,'color','red')
ylabel('Engine Fuel Rate (g/s)')
subplot(4,1,4)
grid on
plot(Eng_Fuel_Consump,'linewidth',1,'color','black')
ylabel('Engine Fuel Consumption [g]')
%%
figure(5)
subplot(3,2,1)
grid on
plot(Time,Acc_Pdl,'linewidth',1,'color','black')
ylabel('Accelerator Pedal [%]')
subplot(3,2,3)
grid on
plot(Time,Brk_Pdl,'linewidth',1,'color','red')
ylabel('Brake Pedal [%]')
subplot(3,2,5)
grid on
plot(Time, Gear_Cmd,'linewidth',1,'color','blue')
ylabel('Gear')
subplot(3,2,2)
grid on
plot(cyc_time,cyc_vel,'linewidth',1,'color','black')
ylabel('vehicle Desired Velocity [m/s]')
subplot(3,2,4)
grid on
plot(Veh_Spd,'linewidth',1,'color','red')
xlabel('Time [s]')
ylabel('Vehicle Actual Speed [Km/h]')
subplot(3,2,6)
grid on
plot(Veh_Dist,'linewidth',1,'color','blue')
xlabel('Time [s]')
ylabel('Vehicle Distance [Km]')
figure(6)
plot(cyc_time,cyc_vel*(18/5),'linewidth',1,'color','green')
hold on
plot(Veh_Spd,'linewidth',1,'color','red')
ylabel('Vehicle Velocity (Km/h)')
xlabel('Time [s]')
legend('Vehicle Desired Velocity','Vehicle Actual Speed')

CASE - 1 : UDDS DRIVE CYCLE

1.

• In first subplot the accelerator pedal and brake pedal application in
  percentage are plotte for the drive cycle.
• The accelerator pedal and the brake pedal are applied as per the drive cycle.
• In the second subplot the transmission input speed and transmission output
  speed are plotted for the drive cycle.
• In the third subplot the gear command from the transmision system is plotted
  for different speeds of the drive cycle.

2.

• In the figure 2 the engine fuel efficiency map i plotted in a contour plot.
• Also the actual or operating engine torque and engine spee is plotted in the
  fuel efficency map.

3.

• In this plot the engine speed wheel spee transmission input speed and
  transmission output speed is plotted in a single plot to compare between
  different component speeds.

4.

• In the first subplot the engine torque is plotted for thge drive cycle.
• In the second subplot the engine power is plotted for the drive cycle.
• In the third subplot the engine fuel rate in g/sec is plotted for the drive cycle.
• In the fourth subplot the engine fuel consumption in g is plotted for the drive
  cycle.

5.

• In the first subplot the accelerator pedal application in percentage is plotted
  for the drive cycle.
• In the second subplot the brake pedal application in percentage is plotted for
  the drive cycle.
• In the third subplot the gear command as per the speed is plotted for the drive
  cycle.
• In the fourth subplot the vehicle desired velocity is plotted for the drive cycle.
• In the fifth subplot the vehicle actual velocity is plotted for the drive cycle.
• In the sixth subplot the total distance covered by the vehicle is plotted for the
  drive cycle.

6.

In this plot the vehicle desired velocity and the vehicle actual velocity is
plotted in one plot to compare between the desired velocity and actual velocity
and to check whether the vehicle can acheive the desired velocity of the drive
cycle.

CASE - 2 : HWFET DRIVE CYCLE

1.

2.

3.

4.

5.

6.

Explanation: All the results are ploted for the same purpose as UDDS but here we use
HWFET Cycle as a input drive cycle.

Conclusion :-

• In this project we leant how to model a conventional vehicle drive train.
• We modele the engine block and vehicle dynamic block using simulink to
  complette the concentional vehicle model.
• We plotted various plots as per requirement in the matlab in the post
  processing script to study the behaviors of the vehicle.
• The fuel economy numbers in kmpl are computed and tabulated for both the
  drive cycle