Week-11 Challenge: Braking
Que. 1) For a defined driving cycle, calculate the energy required for braking.
As we know energy can nither be created nor be destroyed it can be transferd from one form to other form.
we have been able to utilize energy which is been wasted at the time of braking.the kinatic energy which asist the vehical to move also gets dissipated while the braking is done. Though it depends on multiple parameters on how efficient the braking would be it can be dependent upon.
Duration and degree of brake pedal been pressed.
road condition.
temprature.
brake abd disc condition.
mass of the vehical.
still with the basic operation where the vehicle in motion and the brake are aplied the same efficiency could be calculated by the given equation.
BE=0.5mv^2
BE=braking energy
m=mass of vehical
v=velocity
in the same manner the same calculation is been carried out for calculating the brake efficeincy that would be required at the peak point.
Que.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 mtor is at rest and it has to operate from stand stillposition to reach the moderate speed the higher torque is required t bring the motor in operation.whereas when the motor is already is at the high speed the limit is reached by motor operation and thus any further higher tprque s not obtain while braking.the braking operation is happens in thr motion which is been distrubuted as per proportion in the brake energy and the regenrative braking.
How electric and mechanical brakes are coordinated:
in mechanical braking whic we usually see and experiance in all the vehical the brake padel in the vehical cabin help us to engage or disengage the brakes.currently the braking technology hae done wonder by involving life saving braking technology such as ABS,EBD,BA and many others.all this technology play imortant role in stoping the vehical and comng bach to rest from speed condition.in all this vehical when the driver applies the brake the brake pidle comes closer to disc connected with the drivinf disc.the brake pidle helps in efficient braking.
There are two methode by which vehical could brake in electric braking.
1.series-in this regenarative braking and mechanical braking are done one after onather.
2.parallel-in this regenarative braking and mechanical braking are done parallely.
Que.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.
Matlab SCRIPT:
clear all
close all
clc
w=linspace(0,1000)
T=linspace(0,300)
kc=0.18;
ki=0.006;
kw=0.000015;
[X,Y]=meshgrid(w,T)
copper_loss=(Y.^2)*kc
iron_loss=X*ki
winding_loss=(X.^3)*kw
cons=20
o_p= X.*Y
input_power=(copper_loss)+(iron_loss)+(winding_loss)+(cons)+(o_p)
efficiency=(o_p)/(input_power)
n=linspace(0.7,0.95,10)
box off
grid off
contour(X,Y,efficiency,n)
title('SPEED TORQUE CHARACTERISTICS')
xlabel('speed rad/sec')
ylabel('torque n/m')
