Week-11 Challenge: Braking

Breaking system:

There are three types of braking systems are used in vehicle.

1.convetional breaking : hydralic breaks are used.

2.regenarative breaking: electrical breaking

3.engine breaking:

i) mainfold braking

ii) jake break.

Breaking:

An electric motor requires a high current at starting to make a motor run which produces the high torque at the time of starting.

The speed-torque characteristics of an electric motor show us that the torque of a motor will be high and constant for speed below critical speed whereas the torque starts reducing once it reaches the critical speed and maintains the constant power at high speeds, hence EV motors can't develop braking torque at high speeds.

Brake control strategies:

These strategies are used in order to apply the brakes. As the acceleration torque is higher than deceleration torque, only electric braking is not sufficient to stop the vehicle. Also, while reducing the speed, the speed is not directly reduced, as a process, the regeneration takes place.

Up to rated speed, speed and torque is directly propositional to each other and when its reached above rated speed, speed and torque is inversely propositional.

• In such cases to obtain the reduction in speed, series and parallel strategies are used.
• In series, mechanical and electric brakes are applied one after another, whereas, in parallel brakes, these are applied at a time.

In order to control the system, Electric Driven Intelligent Brake System is used in order to control the vehicle. For low-speed generally, only one braking system is used, as a regenerative brake system, whereas for high-speed operations combination is used.

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.

Speed and torque characteristics are shown below: