Challenge

Project 1

SSurya S30 Dec 2021

AIM:

To determine the development of a forward energy-based fuel consumption model of a conventional vehicle.

OBJECTIVE:

1.To build a Simulink model using blocks and complete the vehicel model.

2.To Writing srcipts in MATLAB to load all the varibales required for running the Simulink model.

3.To Tabulate the fuel economy numbers (kmpl) for UDDS and HWFET cycle. This forms the baseline numbers for comparing with the future hybrid version.

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

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

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

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

8.To Write down appropriate brief comments on each of these plots, describing the vehicle behavior throughout the drive cycle.

9.To Generate the plots for both drive cycles.

THEORY:

CONVENTIONAL VEHICLE:

Conventional vehicle use an internal combustion engine fuel by gasoline or disel to power the wheels. In this heat engine uses the prinicple of heat release through combustion of a fuel with an oxidizer in a combustion chamber to crate expanding gases which pushes against a piston creatinf force and torque output.

In this vehicles engine converts chemical energy stored in the fuel into heat which is used to produce useful work. Typically used fossil fuels are petrol and disel.

The most popular type of engine is used in this system is 4 Stroke reciprocating engine. Engine cylincnder process can be represented by ideal thermodynamic cycles such as Otto cycle and Disel engine.

Otto cycle is a ideal cycle that describes the cycle process for spark ignited SI engine and the Disel engine is the ideal cycle that describes the cycle process for a compression iginited CI engine.

ENERGY AND PERFORMANCE OF VEHICLE:

In this system the power demand on the wheel need to instant supplied by the powertrain. The power train is consisits of an engine connected to the wheels through a transmission therefore the power comes from the engine through the transmission.

CONVENTIONAL POWERTRAIN EFFICIENCY:

The engine generates powerr 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,

.mf = Pe/ηe*ηt*QLHV

where,

mf = mass flow rate in(kg)

pe = Power of engine

pt = Power of transmission

nt = Efficiency of transmission

ne = Efficiency of engine

QLHV = lower heating value of fuel

In this system of IC engine if the power at the wheels is zero the engine is idling and still consumes some fuel to over come the engine drag loss and keep it spining this is the idling fuel consumption and know a sidling process.

Above mentioned formula is applicable only when the wheel power is strictly power. When the wheel power is negative either the engine is disenagaged and idling.

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 accesory loads.

SYSTEM DYNAMICS:

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

Each systems has are two generalised variables. They are,

1.Efforts:

It is generalised force variable. Example: torque,force,voltage,heatingvalue.

2.Flow:

It is generalised flow (or) velocity variable. Example: 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. They are,

1.MAP BASED MODELS:

Elements are modeled using maps which characterized the relation ship between th einput 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.

FORWARD MODEL:

It is also known as Dynamic Simulation. Dynamic models are useed for detailed simulations. In this model force or torque or power is the input and th evehicle state variable velocity and acceleration are outputs.

The models and simulations are more realisitc due to physical casuality hence the appopriate for control development.

MATLAB PROGRAM:

clear all
close all
clc

%Inputs
M = 2400;
cr = 0.013;
Rw = 0.35;
cd = 0.35;
Af = 2.4;
rho = 1.225;
Vwind = 0;
g = 9.81;
theta = 0;
road_tire = 1;

%powertrain inputs
FDR = 3.73;
Diffefff = 0.99;

NumGear = 4;
TransGear = [1:NumGear];
TransRatio = [3.06, 1.62, 1, 0.7];
TransEff = 0.90;

TC_SCR = [0, 0.5, 0.6, 0.7, 0.8, 0.87, 0.92, 0.94, 0.96, 0.97, 1];
TC_TR = [2.232, 1.5462, 1.4058, 1.2746, 1.1528, 1.0732, 1.0192, 1, 1, 1, 1];
TC_Cf = 1e-4 * [0.72558, 0.66322, 0.63463, 0.59042, 0.51331, 0.4144, 0.29287, 0.22444, 0.12186, 0.4386, 0];

load vehicle_Data/Engine_data_1_9L_Saturn_95kw
load Vechile_data/Trans_Shift_map

%Driver parameters
kp = 10;
ki = 1;
Drive_Cycle_Select = 1;

%Driver 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);

Time = out.tout;
Acc_pdl = out.Acc_pdl;
Brk_pdl = out.Brk_pdl;
Gear_Cmd = out.Gear_Cmd;

Trans_In_Spd = out.Trans_In_Spd*30/pi;
Trans_Out_Spd = out.Trans_Out_Spd*30/pi;
Eng_Trq = out.Eng_Trq;
Eng_Spd = out.Eng_Spd*30/pi;
Eng_Fuel_Consumption = out.Eng_Fuel_Consumption;

Veh_Spd = out.Veh_Spd*18/5;
Veh_Dist = out.Veh_Dist/1000;
Wheel_Speed = out.wh_speed;
Eng_Fuel_Rate = out.Eng_Fuel_Rate;

Eng_Pwr = Eng_Spd*pi/30*Eng_Trq/1000;
rho_petrol = 0.7197;
kmpl = Veh_Dist(end)/(Eng_Fuel_Consumption(end)/1000/rho_petrol);

%plotting
figure(1)
plot(Time, Trans_In_Spd,'LineWidth',1,'Color','k');
plot(Time, Trans_Out_Spd,'LineWidth',1,'Color','r');
plot(Time, Wheel_Speed,'LineWidth',1,'Color','b');
xlabel('Time[s]')
ylabel('Speed[rpm]')
xlim([0,Time(end)]);
ylim([0,6000]);
legend('Trans Input', 'Trans Output', 'Wheel Speed');
grid on
hold on


Eng_Spd = Eng_Spd.Data(:,1);
Eng_Trq = Eng_Trq.Data(:,1);
Eng_Pwr = Eng_Pwr.Data(:,1);
Eng_Fuel_Rate = Eng_Fuel_Rate.Data(:,1);
Eng_Fuel_Consumption = Eng_Fuel_Consumption.Data(:,1);
Veh_Spd = Veh_Spd.Data(:,1);
Veh_Dist = Veh_Dist.Data(:,1);

%ploting
figure(2)
subplot(2,2,1)
plot(Time, Eng_Trq,'LineWidth',1,'Color','k')
xlabel('Time[s]')
ylabel('Torque[Nm]')
legend('Engine Torque')
grid on

subplot(2,2,2)
plot(Time, Eng_Pwr,'LineWidth',1,'Color','b')
xlabel('Time[s]')
ylabel('Power[kw]')
legend('Engine Power')
grid on

subplot(2,2,3)
plot(Time, Eng_Fuel_rate,'linewidth',1,'Color','r')
xlabel('Time[s]')
ylabel('Fuel Rate[%]')
legend('Engine Fuel Rate')
grid on

subplot(2,2,4)
plot(Time, Eng_Fuel_Consumption,'LineWidth',1,'Color','g')
xlabel('Time[s]')
ylabel('Fuel Consumption')
grid on

%ploting
figure(3)
plot(Eng_Fuel_Consumption,Eng_Fuel_Rate,'Color','r')
xlabel('Fuel Consumption')
ylabel('Fuel Rate[%]')
title('Fuel Economy Vs Fuel Consumption')
grid on

%ploting
figure(4)
subplot(2,1,1)
plot(Time, Acc_pdl,'LineWidth',1,'Color','k')
plot(Time, Brk_pdl,'LineWidth',1,'Color','r')
xlabel('Time[s]')
ylabel('Pedal[%]')
xlim([0, Time(end)]);
legend('Accel','Brake');
title('Accelerattion & Brake Pedal wrt Time')
grid on
hold on

subplot(2,1,2)
plot(Time, Gear_Cmd,'LineWidth',1,'Color','k')
xlim([0, Time(end)]);
xlabel('Time[s]')
ylabel('Gear')
title('Gear command wrt Time')
grid on
hold on

%ploting
subplot(2,1,1)
plot(Veh_Spd,Gear_Cmd,'LineWidth',1,'Color','k')
xlabel('Speed [rpm]')
ylabel('Gear')
title('Gear command wrt vehicle speed')
grid on
hold on

subplot(2,1,2)
plot(Veh_Dist,Gear_Cmd,'LineWidth',1,'Color','r')
xlabel('Distance [kmpl]')
ylabel('Gear')
title('Gear command wrt Distance')
grid on
hold on

%ploting
figure('Name','Engine Operating Points')
grid on
hold 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]')
legend([p1 p3],['Max Curve','Operating Points'])
axis([Eng_map_spd(1)*30/pi Eng_map_spd(end)*30/pi 0 Eng_map_trq(end)]);

SIMULINK MODEL:

In this project, a typical midsize car with a 1.9L engine and a 4-Speed automatic transmission is considered. 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_IntFile.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 there.

DRIVER MODEL:

It is modeled using a Driver block which is a basic PI contoller that generates acclerator and brake pedal outputs to match the desired and actual vehicle speed.

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

OUTPUT FROM SCOPE IN DRIVER MODEL:

CONTROL MODEL:

The control block is the brain of the vehicle which represents 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 io the powertrain block which represents the drivetrain of the vehicle.

1.ENGINE CONTROL UNIT:

In this control model we use engine control unit in that give input engine speed through creating lookup table. In that we given a input Maximum torque and map speed then also create 2nd lookup table in that we given input ct torque and map speed then it subtrats and multiplied. The engine speed is also give to ideal control speed to integrate from this we meet output of engine required torque.

OUTPUT FROM SCOPE IN ECU:

2.TRANSSIMISSION CONTROL UNIT:

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

3.BRAKE CONTROL UNIT:

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

POWERTRAIN:

The powertrain is components that converts the engine's power into movement. This includes the engine, transmission, driveshaft, diffreantial, axles. Basically anything from the engine through to the rotating wheels.

1.ENGINE:

In this model we used map based model to the fuel consumption of engine. It is based on maximum torque and minimum torque form 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.

OUTPUT FROM SCOPE IN DRIVER MODEL: (Engine Torque)

2.TRANSMISSION:

In this model we take engine torque, gear selector form controller for transmission of gear ratio. The ratio is multiply by transmission input torque and then 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.

OUTPUT FROM SCOPE IN DRIVER MODEL:(Transmission in speed, gear ratio, diffrential ratio)

3.DIFFERENTIAL:

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

4.WHEELS:

In this model we take the axle torque form the diffrential and brake torque form controller. It is subtracts and multiplied rolling radius and velocity then we meet the tractive force from axle and brake torque and the wheel speed is meet using velocity.

5.VEHICLE DYNAMICS:

In this we take tractive force and road load. It is discrates vehicle speed based on tractive force and road load.

The dynamic equation for calculation is,

Ftrac = M(dVveh/dt) + 1/2*rho*Af*Cd*(Vveh+Vwind)^2 + Cr*Mgcos(θ) + Mgsin(θ)

Ptrac = pw = MV(dv/dt) + 1/2 * rho * Af * Cd * V^3 + CrMgV

Ew = ki ∫v(dv/dt).dt + ka∫v^3.dt + kr∫Vdt

where,

Rho = Airdensity(kg/m^3)

Af = Frontal Area(m^2)

Cd = Drag Coefficient

Vveh = Velocity of vehicle(m/s^2)

Vwind = Velocity of wind(m/s^2)

Cr = Rolling resistance coefficient

M = Mass(kg)

g = Gravity

Then we calculated and integrate then we meet accleration of vehicle and velocity of vehicle it mean vehicle distance and vehicle speed.

OUTPUT FROM SCOPE IN DRIVER MODEL: (Road load, Acceleration, Tractive force)

OTUPUT FROM SCOPE IN DRIVER MODEL:(Road load)

THE CALCULATION FOR THE FUEL ECONOMY NUMBERS USING UDDS AND HWFET CYCLE:

1.UDDS DRIVE CYCLE:

I)TIME VS SPEED:

The speed is increasing continously.

II)AERODYNAMIC DRAG:

Drag as increase when the power increases.

III)ROLLING RESISTANCE:

Increase when power is increase with respect to time.

IV)TOTAL POWER = AERODYNAMIC DRAG + ROLLING RESISTANCE + INERTIAL RESISTANCE:

OBSERVATION:

Total power is increase slowly as incresing rolling resitance,aerodynamic drag and inertial resistance.

2.HWFET DRIVE CYCLE:

I)TIME VS SPEED:

The speed is continuosly increase with respect to time.

II)AERODYNAMIC DRAG:

Drag as increase when the power increases.

III)ROLLING RESISTANCE:

Increase when power is increase with respect to time.

IV)TOTAL POWER = AERODYNAMIC DRAG + ROLLING RESISTANCE + INERTIAL RESISTANCE:

OBSERVATION:

The total power is increase slowly as increasing aerodynamic drag and inertial resistance. But in this drive cycle bad impact occur due to decreasing rolling resistance.

RESULT:

As comparing the both cycles we used to UDDS drive cycle. It is good for assest of a fuel consumption and pollutants emission of vehicle in a normal way.

MATLAB OUTPUT:

I)Plotting vehicle charcterstics time trace transmission IN OR OUT and Wheel Speed:

In this graph we see that the transmission input and transmission output will flucturates up and down as increasing speed and time.

II)Ploting vehicle charcterstics time trace to Engine Speed, Engine Torque, Engine Power, Engine Fuel Rate and Engine Fuel Consumption:

In this Engine Torque, Engine Power, Engine Fuel Rate, and Engine Fuel Consumption is increaseing with respect to time.

III)Ploting the Fuel Economy VS Engine Fuel Consumption:

In this the engine fuel consumption is suddenly increase as increasing fuel economy but it fuel economy is constant then the fuel consumption is also constant.

IV)Ploting Accelerator Pedal, Brake Pedal and Gear command with respect to time:

In this, comparing brake of vehicle the accelration of vehicle is more so the brake torque is min required and the gear shifiting is also required with respect to time.

V)Ploting Gear Command Vehicle desired with Actual Speed: