Week-11 Challenge: Braking
AIM:
1.For a defined driving cycle, calculate the energy required for braking.
2.Why electric motor can’t develop braking torque at high speed similar to starting? How electric and mechanical brakes are coordinated.
3.Make a MATLAB program which plots contour of given motor speed, torque and efficiency values. Attach the code as a .m file attach a screenshot of all the plots.
Case:1. For a defined driving cycle, calculate the energy required for braking.
As we know that the energy can never be create or niether destoryed with the today's development
We have been able to utilize the energy which is been wasted at the time of braking. The kinetic energy which assist the vehicle to move aslo gets dissipated while the braking is done. Though it depends on multiple parameters on how efficient the braking would be it can be depended upon.
Number of brake pistons
Duration and degree brake pedal been pressed
road condition
Temperature
Brake pad and disc condition
Mass of the disc condition
Mass of the vehicle
Still with a basic operation where the vehicle in motion and the brakes are applied the same efficiency could be calculated by the given equations.
BE=1/2 mv2 (square)
BE= braking energy.
m= mass of the vehicle.
V= velocity.
In the manner the same calculation is been carried out for calculating the brake efficiency that wound be required at the peak point. It being a drive cycle with speed variations the braking power required wound vary but still the highest braking power required is mentioned below.
Braking energy required=160Kj for the speed of 57 kmph.
CASE:2. Why electric motor can’t develop braking torque at high speed similar to starting. How electric and mechanical brakes are coordinated.
#Why electric motor can't develop braking torque at high speed similar to starting.
When the motor is at rest and it is operate from standstill position to reach the moderate speed the higher torque is required to bring the motor in operation. where as when the vehicle is already at high speed the capping ot the limit is reached by the motor operation and thus further higher torque could not be obtained while braking. The braking operation happens in the motion which is been distributed as per proportion in the BRAKE ENERGY and the REGENERATIVE BRAKING.
#How electric and mechanical brakes are coordinated.
In Mechanical braking which we usually see and experience in all vehicles the brake pedal in the vehicle cabin helps us to engage or disengage the brakes. Currently the braking technologies such as ABS, EBD, BA and many others. All these technologies play vital role in stopping the vehicles when the driver applies the brakes the brake peds come closer to the disc connected with the driving disc. The brake pads usually help in efficient braking.
There are two generic methods by which the vehicle could be braked in the ELECTRIC BRAKES.
Series: The Regenerative braking or the mechanical braking noth are applied one after another.
Parallel: The regenerative braking or the mechanical braking both are applied parallely.
When the brake pedal is pressed the hydraulic fluid reaches the brake pistion and created the braking pressure on the wheels and the same kinetic energy is been used by the regenerative braking for generating more power using the Bi-directional motor which operates as a generator while braking.
An example of the proposition of generative braking and the mechanical braking.
NISSAN LEAD- EDIB (Electrionic driven intellegent braking)
EDIB ( electric driven intelligent brake) controls the regenerative brake and friction brake to support both of these requirements. Further, It is also controls the reactive force from the pedal in order to unify the feeling when stepping down on the pedal and the sense of deceleration.
CASE:3.
Make a MATLAB program which plots contour of given motor speed, torque and efficiency values. Attach the code as a .m file attach a screenshot of all the plots.
As we know contour is a graphical techique of representeding 3-dimensional surface. The same is mentioned below for the given details.
% A MATLAB PROGRAMM FOR PLOTTING CONTOUR PLOT OF MOTOR SPEED, TORQUE
clear all
close all
clc
% SPEED ARRAY
w = linspace(0,1000)
% TORQUE ARRAY
T = linspace(0,300)
% LOSS COEFFICIENTS
kc = 0.18; % COPPER LOSSES
ki = 0.006; % IRON LOSSES
kw = 0.000015; % WINDAGE LOSSES
% MESHGRID
[X,Y] = meshgrid(w,T)
copper_loss = (Y.^2)*kc
iron_loss = X*ki
wiindage_loss = (X.^3)*kw
cons = 20
o_p = X.*Y
input_power = (copper_loss)+(iron_loss)+(wiindage_loss)+(o_p)+cons
Eff = (o_p)./(input_power)
n = linspace(0.7,0.95,10)
box off
grid off
contour(X,Y,Eff,n)
title('SPEED TORQUE CHARACTERISTICS')
xlabel('SPEED RAD/s')
ylabel('TORQUE N/m')OUTPUT:
Conclusion: Hence, from the above all question are answers.