Project 1

% 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

Tm = 150 ; %Motor torque

efft = 0.8; %Transmission efficiency

ratio = 2.45; %Total ratio

% Vehicle top speed

Vveh = sqrt((efft*ratio/Rw*Tm - Cr*M*g)*2/rhoa/Af/Cd);

Vveh_kmph = 18/5*Vveh;

%% Power for top speed

Fload = 0.5*rhoa*Cd*Af*(Vveh+Vwind)^2 + Cr*M*g*cosd(theta) + M*g*sind(theta); %Road load in N

Pload = Fload*Vveh/1000; % Road load power in KW

%%% Powertrain speed

omegam = ratio*Vveh/Rw;

omega_rmp = omegam*30/pi;

%% 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);

A driver model is a mathematical model which replicates the functionality of a driver( controlling , monitoring and stabilizing a vehicle )during various maneuvers . In this case, it a PI controller is a basic PI controller that generates accelerator and brake pedal outputs to match the desired and actual vehicle speeds.

The Controller block 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 to the ‘Powertrain’ block which represents the drivetrain of the vehicle.

Objective of powertrain modeling is to analyse the powertrain for various drive cycles & vehicle target performances to decide, Traction Motor sizing (Motor nominal & peak torque and current, RPM, Operating Points at various loads & speeds, motor Power, motor efficiency & motor regeneration energy possibilities etc.)

Equations for aerodynamic drag, rolling resistance, and gradient are implemented and added using simulink blocks to get road load.
Road load is subtracted from the tractive force to get the inertia force. Inertia force is then divided by the mass to get the acceleration.

Acceleartion is integrated to get speed which is again integrated to get distance travelled.

Speed is used in the closed loop operation.

'To workspace' bloacks are implemented in the models for further calulations and plotting.

UDDS -> 13.63 km/litre

HWFET -> 16.3072 km/litre

The fuel economy numbers shows that highway fuel economy is higer than the city fuel economy. Form the graph of acceleration and brake pedal it is clearly observed that there is a lot more braking and idling in UDDS than in the HWFET. Hence highway fuel economy , maximum and mean speeds are higher in HWFET. Also, the fuel consumption and fuel rate are higher in HWFET due to higher maximum and mean speeds and lesser disruptions.

Power consumption and Engine torque are more in the UDDS compared to HWFET cycle because it has too many starts and stops compared to
HWFET. More power is required when starting from rest and more torque is required to overcome static friction.

Accelerator, brake pedal and gear shifting:
For UDDS, the accelerator and the brake pedal have more fluctuations due to frequent starts and stops. But in HWFET, the brake pedal fluctuations are almost near to the zero line as there are no frequent stops or disruptions.
UDDS cycle mostly runs on 1st, 2nd gears, and 3rd and 4th are rarely used as it is not possible to achieve high speeds in city traffic. In the HWFET cycle, the vehicle mostly runs on 3rd, 4th gears as it will be moving at high speeds. 1st, 2nd gears are used rarely and only when braking is required.
vehicle speeds(maximum and mean speeds) are higher in HWFET compared to UDDS. UDDS has more fluctuations in the speed due to frequent braking.
The distance travelled in the given time will be high in HWFET than UDDS in a given time as there are no disruptions like frequient braking due to city traffic.