Challenge: Braking
1. For a defined driving cycle, calculate the energy required for braking.
A Matlab script is attached with a 100 s drive cycle and braking energy calculated.
E=½*m*v^2 (used when the vehicle slows down)
m⇒ mass of vehicle
v⇒ velocity of vehicle
The braking energy of this drive cycle is 25573 kJ
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2. Why can't electric motors develop braking torque at high speed similar to starting? How electric and mechanical brakes are coordinated?
When the motor is at rest and it has to operate from a standstill position to reach the moderate speed the higher torque is required to bring the motor into operation. Whereas when the vehicle is already at high speed the capping or the limit is reached by the motor operation and thus any further higher torque could not be obtained while braking. The peak acceleration torque of the motor may not be equal to the peak acceleration torque of the motor because at high speed the motor is operating in field weakening region. In the field weakening region, the motor torque is limited by the voltage applied. The braking operation happens in the motion which is been distributed as per proportion in the BRAKE ENERGY and the REGENERATIVE BRAKING.
Most of the EV & HEV follows the combined braking operation
Series operation:
In the series operation, the electric brake and mechanical brake are applied one after another. Only one brake can be employed at the time.
Parallel operation:
In the parallel operation, the electric brake and mechanical brake are applied simultaneously. Here both the brakes can be employed at the time of operation.
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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
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https://drive.google.com/drive/folders/1CDvlqxvw0LHid595NiuqttK4VsXVun8E?usp=sharing