Regenerative Braking
Regenerative Braking
Now a days we can see that revolution
in vehicle industry has been increasing day by day. Also, we know that after
few years there will be no fossil fuel left. So how will vehicles actuate
without petrol and diesel….??
So yes, answer to this is Electric
Vehicle (EV).
The global
fossil fuels reserves are finite. Instead, the use of electricity, produced by
renewable energy sources and stored chemically in some medium like hydrogen or
batteries is a, long term, environmentally friendly, cost-effective,
zero-emission solution for endless automotive power supply
History of Electric Vehicles
The first ever electric vehicle was
manufactured in 19th century in U.S. which was 6 passenger car and
which capable of top speed 14 miles per hour.
This phenomenon led to a spark in
Automotive industry.
Tesla motors in 2008 released first
ever completely electric Roadster which was capable of running 254 km on single
charge. This was the time when there was big revolution in Automobile industry.
In Electric Vehicles, the source for energy is only battery and these batteries face problem like less charging and recharging cycles also they have poor driving range so to overcome this problem there is invention of concept called regenerative braking.
Regenerative Braking
When vehicle starts decelerating its
kinetic energy is converted into electric energy so that this generated
electric energy can be stored, this concept is called regenerative braking.
Consider a vehicle with 250 kg of mass
moving with initial velocity of 54 km/h, now on braking vehicle to a speed of
36 km/h the amount of energy spent is 15.625 kJ.
The energy calculated is using
equation,
If we consider ideal condition, this amount of energy is available for capturing. If we use the concept like regenerative braking on such vehicles then we are able to capture this amount of energy and can be reused this same energy which would otherwise have been wasted in the form of heat, sound etc. If the efficiency of Regenerating energy is considered at least 20% then there would still be an amount of 3.125 kJ (20% of 15.625kJ) of energy is available at every time of braking , so we can see that much amount of energy that can be utilized for beneficial causes.
Working Principle of Regenerative braking
Regenerative
braking is basically a brake method to use mechanical energy from the motor at
the time of deceleration and convert kinetic energy to electrical energy and
give back to the battery. When we apply force on brake pedal, then car gets
slow down and motor starts working in reverse direction. When running in
opposite direction motor acts as the generator and thus it charges the battery.
When driver
stop pushing acceleration pedal, the vehicle starts decelerating and motor
controller gives command to generator as negative torque develops in motor so
motor acts as generator and drives current from motor to battery.
Regenerative braking using Ultracapacitor
An ultracapacitor
is a energy storage device also known as a supercapacitor, or electrochemical
capacitor. Now a days ultracapacitor is growing popularity in EV industry. Ultracapacitor’s
design is somewhere between an ordinary capacitor and a battery.
Let’s take
an example,
Set of small batteries and ultracapacitor which works in coordinated manner is equal to a set of large battery.
Basic components and circuit of Regenerative braking using ultracapacitor
Motor controller-It
is a device that acts as intermediary between batteries and motors. The
output of all sensors is given to motor controller.
Inverter-It converts AC current generated from motor to DC current.
Bi-directional
DC-DC converter-It
decides where should the generated current should go i.e. to ultracapacitor or
to battery.
The
controller DCDC converter, which work as buck-boost converter. The boost
operation basically transfers charge to battery from ultracapacitor and is used
for acceleration while buck operation is use for deceleration, which helps in
charging capacitor.
Advantages of Regenerative Braking
Implementing
Regenerative braking in a vehicle provides us many advantages as-
1: It increases the driving range of a
vehicle.
2: It helps us to reduce the battery size
of vehicle.
3: As battery size gets reduced, thus weight of vehicle is reduced so there will be increase in performance of vehicle.
Switching Model Of The Regenerative Braking
The diodes are
linked parallel with every MOSFET.
Those diodes
can be used as freewheeling diode such for that PWM can be useful to switch
devices, thus the efficiency of system is perfect.
1: Driving mode of bldc motor
Here, Current flows from positive side
of battery to negative.
2: Initial stage of braking
When the
brakes applied to the vehicles, when vehicle is in motion the system switches
to braking mode. During first stage of brake the back emf and battery goes in
series. In this Q2, Q3 are switched on and Q1,Q4 are switched off, so the
direction of armature current can be easily changed.
3: Regenerative braking
Q1 and Q4 are switched on and Q2 and
Q3 are switched off so that armature current can change its direction and
Regenerative braking can start.
Conclusion
The Regenerative braking is one of the
most important part of vehicle.
Regenerative braking can save 05-30% of
waste energy.
Zeher info👍👍
ReplyDelete🔥🔥🔥🔥🔥🔥🔥
ReplyDeleteGood work keep it up
ReplyDeleteVery Informative 👍👍
ReplyDelete