Project 1

Aim:

1. Tabulate the fuel economy numbers (kmpl) for UDDS and HWFET cycle. This forms the baseline numbers for comparing with the future hybrid version.
2. Plot the time trace for engine, transmission input, transmission output and wheel speed on one plot.
3. Plot engine torque, engine power, fuel rate and fuel consumption using subplots.
4. Plot accelerator and brake pedal, gear command, vehicle desired and actual speed, vehicle distance using subplots.
5. Plot the engine operating points on the engine fuel map.
6. Write down appropriate brief comments on each of these plots, describing the vehicle behavior throughout the drive cycle.
7. Generate the plots for both drive cycles.
8. Study the conventional vehicles and generate graphs.

Conventional Vehicles -

Conventional vehicles use Internal Combustion Engines (ICE) To power the vehicles and those engines are fuled by the gasoline or diesel to power the wheels.

In this vehicle engine converts the chemical energy from fuel to convert into mechanical work. by using fossil fuels.

The most popular type of engine is the four stroke engine and Engine is run on ideal thermodynamic cycles such as Otto cycles,Diesel cycle and Dual Cycle.

Energy and performance of the vehicle -

In this system the power demand on the wheel need is instantly supplied by the powertrain and that power is used for the propulsion of the vehicle. In the conventional vehicles the engine is connected to the wheel through the transmission.

Power train efficiency -

The engine genrates power by using the stored chemical energy and converting that into the mechanical energy by the combustion process and all of this process has some efficiency.

The efficeincy of the powertrain is given by -

`dot Mf = (Pe)/((etae)*(etat).QLHV)`

Where,

Mf = mass flow rate in Kg

Pe = power of engine

ne = efficeincy of engine

nt = Transmisson efficeincy.

QLHV = Calorific value of the fuel.

The engine consumes fuel even if we are idling and also in the case of braking and in that case engine might be losing fuel because we are not getting the desired work output.

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 modelling of the multi dynamic system through the approch by using ordinary differential and algebric equation which describes the static and dynamic behaviour of the system.

In each system there are 2 generalised variables -

1) Effort - It is the generalised force variables i.e Torque,force,Voltage,Heating value.

2) Flow - It is genralised velocity variable. i.e Velocity,current.

Energy based Models -

There are two energy based models which helps us to analyze the flow of energy.

1) Map based Models - Elements are modeled using maps which characterise the relationship between input and output also ouput and losses.

2) Analytical Models - Elements are modeled using physical equations that represents the internal dynamics of the system.

In this we use Forward Models -

Dynamic models are used for detailed simulation of the given system. In this model we give force,torque and power is the input and the vehicle state variable velocity and acceleration are outputs. The models and simulattions 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 - Pranav Sanjay Jadhav

% 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.

1] Driver Model -

The output of the driver block is to get accelrator and brake pedal outputs to get desired vehicle speed and power to the wheels It is based on time, velocity then its all integrate and creates output accelration pedal and brake pedal.

Output of the driver model -

2] Control Model -

The control model is the brain of the system and its electronically controlled system. It is based on the drivers input and from that it has to generete the required torque, desired transmission gear and desired brake torque. These all Inputs are further given to the powertrain.

1) Engine Control Unit -

Engine control unit is only responsible for the variables related to the engines and it only controls that part about the engines.

Ouput of the Engine control unit -

2) Transmission Control Unit -

In this control unit we only try to control the gears of the vehicle as in the shifting and the ratios of the gear and provide steady state vehicle speed in kmph or in mph.

3) Brake Control Unit -

Brake control unit takes the input from the driver and according to that it generates the brake torque in order to stop the vehicle and bring the vehicle to rest It takes input from the driver.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 use map based model to model the fuel consumption of engine. It is totally based on maximum torque and minimum torque from the controller then it saturated torque and give output then saturated and speed map give fuel consumption takes the speed and torque goes into saturated then its integrated.

Output from the Engine block -

2) Transmission -

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.

Output from the Transmission block -

3) Diffrential -

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.

`M e q d V v e h d t = η t λ t o t R w T m − ( 1 2 p ⋅ A ⋅ C d ⋅ ( V v e h + V w ∈ d ) 2 + C r ⋅ M ⋅ g ⋅ cos ( θ ) + M ⋅ g ⋅ sin ( θ ) )`

Where,

p = air density kg/m^3

A = frontal area m^2

Cd = drag coefficient

Vveh = Velocity of vehicle. m/s

Vwind = Velocity of wind. m/s

M = Mass in. KG

g = acceleration due to gravity.

1] UDSS Drive Cycle -

1) Speed Vs Time - The graph is increasing continuosly.

2) Aerodynamic Drag - Drag increases when the power increases.

3) Rolling Resistance - Power increases with time.

4) Total Power = aerodynamic drag + rolling resistance + Inertial force.

Conclusion -

This means total power increases slowly as increasing rolling resistance,aerodynamic drag and inertial resistance.

2] HWFET Drive cycle -

1) Speed Vs time - Speed is Continuosly increasing with time -

2) Aerodynamic drag - Drag increases when the power increases.

3) Rollling resistance - In this resistance is increase with time

4) Total Power = aerodynamic drag + rolling resistance + inertial resistance.

Conclusion -

Total Power is increase slowly as increasing aerodynamic drag and inertial resistance. but in this drive cycle bad impact occurs due to decreasing rolling resistance.

Now For creating Plots we use MATLAB coding So the coding will give down:-

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Skill-Lync -> Hybrid Drives Development
% Project 1 - Conventional Vehicle Model
% By - Pranav Sanjay Jadhav 

% 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)]);

1] Plotting vehicle characteristics time trace transmission IN/OUT and Wheel Speed:-

In this graph we see the transmission input and transmission out will fluctuates up and down as increasing speed and time.

2] Plotting vehicle characteristics time trace to Engine speed, Engine Torque, Engine Power, And Engine fuel rate, Engine fuel consumption.

3] Plotting fuel economy Vs Engine Fuel consumption:-

In this type of graph the fuel consumption is suddenely increase as increase as fuel economy but if fuel economy is constant then the fuel consumption is also constant.

4] Plotting Accelerator pedal, Brake pedal and gear pedal with respect to time -

In this the as comparing brake of vehicle the accelaration of vehicle is more so the brake torque is min required. and the gear shifting is also required with respect to time.

5] Plotting gear command vehicle desired with actual -

In this the gear shifting is required as increase vehicle speed. as shifting order is gear1, then gear2, then gear3, and then gear4.

6] Plotting engine operating points on engine fuel map -

In this decrease torque speed is increase.