Week-11 Challenge: Braking
NOTE- THIS IS EV LIVE BATCH 21.
ANS-1:-
As we are taking total weight (curb weight+load )=800Kg
We have created a excel file (attached) as drive cycle.There are breaking points which are highlited -
for 1st braking point--
v goes 5m/s to 0m/s in 5 sec.
so v=1m/s
So energy required to stop the vehicle is 0.5*m*v^2
Ke1=0.5*800*(1)^2
=400 J
For 2nd breaking point-
v goes 25m/s to 0m/s in 9 sec.
so v=2.77 m/s
So energy required to stop the vehicle is 0.5*m*v^2
Ke1=0.5*800*(2.77)^2
=3069 J
for next breaking point-
v goes 85m/s to 15m/s in 10 sec.
so v=7 m/s
So energy required to stop the vehicle is 0.5*m*v^2
Ke1=0.5*800*(7)^2
=19600 J
So by doing same process ,we can calculate for any point.
Ans-2:-
As motor torque-speed characterstics-
- In DC motor,when load on motor is constant ,speed is proportional to the supply voltage.And when supply voltage is constant,speed is inversely proportional to torque.
- In constant torque region,higher speed can be possible,and then the vehicle reach at constant power region.
- When breaking action happens,torque goes to negative and as vehicle is in power constant so at this time,torque generated by motor is less than the required.
- There are mostly two Braking system-Regenrative and mechanical braking.
How electric and mechanical brakes are coordinated-
- In electrical brake system,it is also known as regenrative brake system.In this when vehicle is deaccelerate then motor work as generator and it provide the voltage to charge the battery.But in high speed it,is not posible to control the vehicle by regenrative brake .If the power requirmnet in regenrative system is more than battery capacity then mechanical brake should be needed.
- Mechanical break is taken happen by pulling the paddel.
- there are two braking control strategy-
1>series-In this ,we apply mechanical or regenrative breaking one after another.
2>Parellel-We apply both mechanical and regenrative brake simultaneously.
By above two methods electriocal and mechanical brakes coordinate each other.