Project 1
Aim :-
1.Build Simulink model using blocks and complete the vehicle model.
2.Writing scripts in MATLAB to load all the variables required for running the Simulink model.
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.
Conventional Vehicel :-
Conventional vehicle using use an internal combustion engine fueled by gasoline or diesel to power the wheels. In 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 force 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.
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 that describe the cycel process for spark ignited SI engine and the Diesel cycle is the ideal cycle that describe the cycle process for a compression ignited CI engine.
Energy and performance of vehicle :-
In this system torque power demand on the wheel need to instant supplied by the powertrain. In the other word the power coming from the powertrain dicates the power demand on the wheels (as per performance, acceleration, speed etc is determined by it.
In this vehicle the powertrain is consists of an engine connected to the wheels through a transmission therefore the power comes form the engine through the transmission.
Conventional Powertrain 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 comsumption.
Instantaneous fuel consumption is given as
mf=Peηe.ηt.QLHV
Where,
mf = mass flow rate in kg
pe = power of engine
nt = efficiency of transmission
ne = efficiency of engine
QLHV = it is the calorific value/lower heating value of fuel.
In this sytem of IC engine if power at the wheel 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 a idling process. Above mentioned formula is appicable only when the wheeo power is strictly power. When the wheel power is strictly power. When the wheel power is negative either the engine is disengaged and idling or the engine 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 system through the use of a unified approach based on a ordinary differential and algebric equation describing the static and dynamic effects.
Each systems has are two generalised variables ;
1. Efforts - it is generalised force variable eg;- torque,force,voltage,heating value.
2. Flow - it is generalised flow/velocity variable eg;- velocity,current,mass flow rate.
3. Power - it is the product of the effort and flow variable it is interchange between energy domains.
Energy based models :-
To models the internal physical properties of the element and the loses there are basically two kinds of approach.
1)Map based models :-
Elements are modeled using maps which characterized the relatioship between the input and outpue, and losses etc.
2)Anlaytical models :-
Elements are modeled using physical equation that represents the internal dynamics. These are the two extreme 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 simulation. In this model force/torque/power is the input and the vehicle state variable velocity and acceleration are output. The models and simulations are more realistics due to physical casuallu 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 sysem helps significantly in control development.
Matlab Scripts :-
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% 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);In this project a typical mid size car with a 1.9L enging and a 4-speed automatic transmission is considered. Data is taken for data base developed by NREL,USA,Transmission shift map and controller is taken from Matlab/Simulink example database.
Teh model developed has the capability to simulate the vehicle on different drive cycle like UDDS,HWFET,FTP,NEDC,etc.
"Project1_InitFile.m" is a Matlab script used to load all the variable required for running the simulink model and for post-processing. The drive cycle selection is also done here. Before running the simulink vehicle is model, run this intialization script.
Driver Model :-
It is modeled using a Driver block, which is a basic PI controller that generated accelerator and brake pedal ouputs to match the desired and actual vehicle speeds. In this we use drive cycle the based on these result of fuel consumption and emission 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 acceleration pedal and brake pedal.
Control Model :-
The 'Contorller' 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 transimssion gear and desired brake torque. These inputs are fed to the 'Powertrain' block which represents the drivetrain of the vehicle.
Engine Conrol Unit :-
In this control model we use engine control unit in that give input engine speed through creating look up table. In that table we give input maximum torque and map speed then also create 2nd look up table in that give inpyt 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.
Transmission Control Unit:-
In this unit we create steady 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 moh.
Brake COntorl Unit :-
In this calculate brake torque and then all three control signals output is give to powertrain.
Powertrain:-
The power train encompasses every component that converts the engine power into movement. This includes the engine, transmission the driveshaft, differentials, axles; basically anything from the engine through to the rotating wheels.
Engine :-
In the model we used map based model to model 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.
Transmission :-
In these model we take engine torque gear selector from controller for transmission input torque and then the transmission input torque and then the transmission efficicency 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.
Differential :-
In this taking input is the transmission output then its gooing to the differential ratio multiplied the output and input torque then meet axle torque. The axle torque if a lower than the transmission torque and differential ratio.
Wheels:-
In this model we take the axle torque from differential and brake torque form controller. It is subtracts and multplied rolling radius and velocity then we meet the tractive force axle and brake torque and the wheel speed is meet using velocity.
Vehicle Dynamics:-
In this takes tractive force and road load. It is dicates vehicle speed based on tractive force and road load the dynamic equation for calculating road load is
Meq*(dVveh/dt) = (nt(lamda)tot/Rw)*Tm - 1/2*rhoa*Cd*Af*(Vveh+Vwind)^2 + Cr*M*g*cosd(theta) + M*g*sind(theta)
Where,
rhoa = air density
A = Frontal area
Cd = Drag coefficient
Vveh = Velocity of vehicle
Vwind = Velocity of wind
Cr = Rolling resistance coefficient
M = Mass
g = gravity
Then we calculate and integrate then we meet acceleration of vehicle and velocity of vehicle lit mean vehicle distance and vehicle speed.
Drive Cycles :-
1.UDDS
2.HWFET
UDDS and HWFET Drive Cycles:-
Time Vs Speed
Aerodynamic Drag
Rolling Resistance
Total Power
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 - Ullekh Gambhira
% 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)]);
figure(1)
hold on
grid on
plot(Time, Eng_Fuel_Consump,'linewidth',1,'color','black')
plot(Time, fuel_rate.Data,'linewidth',1,'color','red')
xlabel('FUEL CONSUMP')
ylabel('Fuel RATE')
legend ('FUEL CONSUMP','FUEL RATE')
figure(2)
hold on
grid on
plot(Time,Eng_Spd.Data,'linewidth',1,'color','g')
plot(Time, Trans_In_Spd,'linewidth',1,'Color','black')
plot(Time, Trans_In_Spd,'linewidth',1,'Color','red')
plot(Time,Wheel_speed,'linewidth',1,'color','blue')
xlabel('Time(S)')
ylabel('Speed [rpm]')
Xlim([0, 6000])
legend('ENGINE SPEED','Trans Input''Trans Output','WHEEL SPEED')
figure(3)
subplot(2,2,1)
grid on
plot(Time, Eng_Pwr.Data,'linewidth',1,'Color','g')
xlabel('Time [S]')
ylabel('Power (KW)')
legend('Power')
subplot(2,2,2)
grid on
plot(Time, Eng_Trq.Data,'linewidth',1,'color','black')
xlabel('Time [S]')
ylabel('Torque (Nm)')
legend('torque')
subplot(2,2,3)
grid on
plot(Time, fuel_rate.Data,'linewidth',1,'color','y')
xlabel('Time [S]')
ylabel('fuelrate')
legend('fuel rate')
subplot(2,2,4)
grid on
plot(Time, Eng_Fuel_Consump.Data,'linewidth',1,'color','blue')
xlabel('Time [S]')
ylabel('consumption')
legend('consumption')
figure(4)
subplot(3,1,1)
hold on
grid on
plot(TIme, Acc_Pdl,'linewdith',1,'color','black')
plot(Time, Brk_Pdl,'linewidth',1,'color','blue')
xlabel('time')
ylabel('pedal trace %')
xlim([0,Time(end)])
legend('acc','brake')
subplot(3,1,2)
hold on
grid on
plot(Time,desired_spd.Data,'linewidth',1,'Color','black')
plot(Time,Brk_Pdl,'linewidth',1,'color','blue')
xlabel('time')
ylabel('RPM')
xlim([0, Time(end)])
legend('desired speed','actual speed')
subplot(3,1,3)
hold on
grid on
plot(Time, Gear_Cmd,'linewidth',1,'color','black')
xlabel('time')
ylabel('Gears')
xlim([0,Time(end)])Conclusion :-
The Build Simulink model using blocks and complete the vehicle model. Writing scripts in MATLAB to load all the variables required for running the Simulink model are clearly execute and plotting successfully.