Week-11 Challenge: Braking

Answer 3:

clear all
close all
clc
speed=linspace(0,2000,500);
torque=linspace(0,500,200);
kc = 0.1; % Copper Loss constant
ki = 0.002; % Iron Loss Constant
kw = 0.0003; % Windage Loss Constant
Cm = 25; % Motor Loss Constant
[X,Y] = meshgrid(speed,torque);
outpower=X.*Y;
Totalloss = ((Y.^2).*kc)+ (ki.*X)+((X.^3).*kw)+Cm;
inpower=outpower+Totalloss;
E=outpower./inpower;
cone=[0.70,0.72,0.75,0.77,0.79,0.80,0.81,0.82,0.83,0.84,0.85,0.86,0.87,0.88,0.89,0.90,0.91,0.92,0.93,0.95];
contourf(X,Y,E,cone)
colorbar
xlabel('Speed (rpm)');
ylabel('Torque (N.m)');
title(' Efficiency Contour');

Answer 2:

Regenerative braking is an energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy into a form that can be either used immediately or stored until needed. In this mechanism, the electric traction motor uses the vehicle's momentum to recover energy that would otherwise be lost to the brake discs as heat. This contrasts with conventional braking systems, where the excess kinetic energy is converted to unwanted and wasted heat due to friction in the brakes, or with rheostatic brakes, where the energy is recovered by using electric motors as generators but is immediately dissipated as heat in resistors. In addition to improving the overall efficiency of the vehicle, regeneration can significantly extend the life of the braking system as the mechanical parts will not wear out very quickly.

Series Control Strategy:

• Its the combination of friction-based mechanical braking system with a regenerative braking system that transfers energy to the battery with an integrated control, which distributes the required braking force between the regenerative braking system and the mechanical braking system.
• Series Startegy could give an increase of 15-30% in fuel efficiency and has more consistent braking due to good torque blending capability.

Parallel Control Strategy:

• It is the combination of mechanical and the regenerative braking system, operated simultaneously without an integrated control.
• The regenerative braking force is added to the mechanical braking force which cannot be controlled.
• The regenerative torque is determined by considering the motor capacity, battery SOC, and vehicle velocity. The regenerative braking force is calculated from the brake control unit by comparing the demanded brake torque and the motor torque available.

Answer 1:

First Braking : 12-7m/s in 3 seconds

Second Braking :9-6.66m/s in 4 second

Third braking :11-7m/s in 7 seconds

Fourth braking :14.7-0m/s in 10 seconds

Here the energy is calculated by 1/2mv^2

where v= final velocity-initial velocity

then it power in kW is calculated.

Calculations are done using excel calculator