Week-11 Challenge: Braking

1)For a defined driving cycle, calculate the energy required for braking.

There are 2 types of braking

1) Regenrative braking

2) Mechanical braking

this brakings are required to stop the vechile from a given speed to stop the vechile.

this is the graph of speed and time by this we can calculate the required braking energy.

by use of the formula :-

K.E = 1/2*m*v^2

we can calculate the energy required for braking.

unit of kinetic energy is joule

where m = mass of vechile (pay load +vechile mass) ,kg

v = velocity (velocity intial - velocity final), m/s

for example mass of vechile is 1000kg and intial vel is 100m/s anf final vel is 0 so the energy reqired for braking is

k.e = 0.5*1000*(100-0)

k.e = 50000 J or 50 KJ

2)Why electric motor can’t develop braking torque at high speed similar to starting? How electric and mechanical brakes are coordinated?

At the start of motor the current supplied is very large due to which toruqe will be more as it directly praportional to square of current.

so at time of brake the current value is within range so the torque also within range so it will always less from starting torque.

b) speed torque charaterstics

At the starting the torque value is very high as speed is very low as speed increases the torque value will decrease to maintain constant power so at the time of braking the speed value is high and torque value will be low so at time of braking the braking torque value will be low.

so in order to stop the vehicle both regenrative and mechanical braking is required.

they are of two methods to apply them:-

1) series braking :- in this mechanical and regenrative brakes are applied one after another.

2) parallel braking :- in this both mechanical and regenrative brakes are applied simantounesly .

at low speed we use regenrative braking at high speed we use mechanical braking and little regenrative braking.

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.

output:-

the yellow parts indicate high efficency as the the torque and speed increases efficency will decreases at low speed the efficency will be more .