Calculate fuel consumption rate for a given vehicle operating condition.

Q1) Calculate fuel consumption rate for a given vehicle operating condition for all feasible gears. Select the gear that results in the lowest fuel consumption.

To calculate fuel consumption rate from engine operating condition, use Engine data provided (Engine_data_1_9L_Saturn_95kW.mat). Use “interp2” function in Matlab to find the fuel consumption value from the 2d map data provided.

what is interpolation?

Interpolation is a method of fitting the data points to represent the value of a function. It has a various number of applications in engineering and science, that are used to construct new data points within the range of a discrete data set of known data points or can be used for determining a formula of the function that will pass from the given set of points (x,y).

clear all
 close all
  clc
% loading the data file
  load Engine_data_1_9L_Saturn_95kW.mat
%%  variables
% pw = wheel power kw
% Vveh = vehical velocity kmph
%Rw = wheel radius m
%omega_w = wheel speed
%Tw = wheel torque
%Pe = engine power
%omega_e = engine speed
%Te = engine torque
%% engine and transmission operating condition
Pw = 35*1000;                                                      %wheel power  kw to w
Vveh = 90*(5/18);                                                 % vehical speed  m/s
Rw = 0.35;
final_drive_ratio = 3.73;
final_efficiency = 0.99;
efficiency = 0.9;
% gear = [1,2,3,4] ;
ratio = [ 3.06 , 1.62 , 1 , 0.7 ];
% compute wheel power and wheel speed
omega_w = Vveh/Rw;                                                       
Tw = Pw/omega_w;

Pe = Pw/efficiency;                                                              % power
omega_e = (omega_w*final_drive_ratio).*ratio;                 % engine speed in m/s to rpm 
Te = Pe./omega_e;                                                                % engine torque
  
SPEED= linspace(Eng_map_spd(1),omega_e(1),11);
TORQUE=linspace(Eng_map_trq(1),Te(end),12);
FUEL=interp2(SPEED,TORQUE,Eng_fuel_map,omega_e,Te);

[A,B]=meshgrid(Eng_map_spd,Eng_map_trq);

figure(1)
contourf(A,B,Eng_fuel_map','showtext','on')
xlabel('Engine speed')
ylabel('Engine trque')
zlabel('Eng fuel map')
title('FUEL MAP')
colorbar

figure(2)
surf(A,B,Eng_fuel_map')
xlabel('Engine speed')
ylabel('Engine trque')
zlabel('Eng fuel map')
colorbar

figure(3)
contourf(A,B,Eng_eff_map','showtext','on')
xlabel('Engine speed')
ylabel('Engine trque')
zlabel('Eng efficiency map')
title('EFFICIENCY MAP')
colorbar
figure(4)
surf(A,B,Eng_eff_map')
xlabel('Engine speed')
ylabel('Engine trque')
zlabel('Eng efficiency map')
colorbar


fprintf( '\n FUEL CONSUMPTION AT GEAR 1 = %f  g/Kwh' , FUEL(1) )
fprintf( '\n FUEL CONSUMPTION AT GEAR 2 = %f  g/Kwh' , FUEL(2) )
fprintf( '\n FUEL CONSUMPTION AT GEAR 3 = %f  g/Kwh' , FUEL(3) )
fprintf( '\n FUEL CONSUMPTION AT GEAR 4 = %f  g/Kwh' , FUEL(4) )

explanation

we are first providing the input data to calculating the speed and torque at gear1 ,2,3,4.

for speed array we used linspace comand whose starting will be from first value of engine map speed and the end value will be the first value of engine speed with 11 quentity.

because engine speed highest value is first gear ratio.

for torque array we used linspace comand whose starting will be from first value of engine map torque and the end value will be the end value of engine torque with 12 quentity.

because engine torque highest value is with fourth gear ratio.

now because engine fuel map is having 12x11 format we need to make speed and torque in 12x11 format .

and then with interp2 function where x,y are speed and torque ,V contains the corresponding function values of engine fuel map . Xq and Yq are the inputs. which will give us the fuel consumption rate.

plots

fuel map

plotting engine speed vs engine torque with engine fuel map

plotting engine speed vs engine torque with engine efficiency map.

Q2) Create a Simulink Stateflow chart similar to the one shown in the lecture. This Stateflow is used to represent the function of the Supervisory Controller. This will be used in the final project

refrences

https://x-engineer.org/brake-specific-fuel-consumption-bsfc/

https://www.youtube.com/watch?v=gcGAkYtmGe4

thank you