Week-11 Challenge: Braking

1. A drive cycle with following speeds at various time periods defined

breaking energy consumed during this life cycle is also calculated

excel sheet is also attached

2.

To understand this we need to have a closer look of speed, torque ad efficiency contour of ev motor in both first and second quadrants i.e., forward motoring and forward breaking quadrants. Motors are operated in two regions constant torque and constant power. During starting motor has constant torque irrespective of and after field weakening motor is operated at constant power. For any given operating point to switch from motoring to breaking it can be observed that torque available is less than starting torque.

Coordination between electrical and mechanical brakes is important as there should be no compromise between effective breaking and energy generation. Breaking shouldn’t completely dependent on neither of them and needed to be effectively distributed among friction and electric case by case. Coordination is basically two types

Series

Parallel

Series: In series both types of breaks applied one after other. Ideally friction brake first and then regenerative brake next as higher amount of power generated at lower speeds as operation is in constant torque region.

Parallel: In parallel both types of breaks applied simultaneously. The combination percentages of each brake can be selected inorder to maximize power generation, comfort and deceleration time.

3.

contour .m file attached and screen shot of output also attached