Authors: Pia Žnidaršič, Tina Rejc, Mitja Železnik
Mentor: Tomaž Kušar
Charging
solar panels
wireless charging
regenerative braking
Hypothesis
A good part of the car’s kinetic energy can be
converted into electricity with the use of regenerative
braking system. In such a way, we can improve the
car’s efficiency.
The electric car still needs ordinary brakes alongside
the regenerative braking system due to its slow braking
ability.
The construction of the electric car
Research
video clip: our experiment
We tried to find out an answer to the question: how to
improve the electric car‘s efficiency?
𝜂[%] =
𝐴𝑒
𝑊𝑝
1. We compared a basic diode and light emitting diode.
2. We also used different capacities of a capacitor.
Measurements
At first we measured the braking
distance while the DC motors weren‘t
connected to an electric circuit. Total
potential energy is converted to the
force of friction (braking force).
𝑊𝑝 = 𝐴𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝑎𝑙 𝑓𝑜𝑟𝑐𝑒 1
𝑊𝑝 = 𝑚 ∙ 𝑔 ∙ ℎ
𝑥1 … … … 𝑏𝑟𝑎𝑘𝑖𝑛𝑔 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒
braking distance
Then we measured the amount of
electricity converted from kinetic
energy by the DC motors (generators).
𝑥2 … … … 𝑏𝑟𝑎𝑘𝑖𝑛𝑔 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒,
while regenerative braking
system was used
𝐴𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝑎𝑙 𝑓𝑜𝑟𝑐𝑒 2 =
𝑥2
∙ 𝑊𝑝
𝑥1
𝐴𝑒 = 𝐴𝑓𝑟.𝑓𝑜𝑟𝑐𝑒 1 - 𝐴𝑓𝑟.𝑓𝑜𝑟𝑐𝑒 2
𝑊𝑝 = 𝐴𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝑎𝑙 𝑓𝑜𝑟𝑐𝑒 2 + 𝐴𝑒𝑙
𝜂[%] =
𝐴𝑒
𝑊𝑝
Results
𝐴𝑒𝑙 = 𝑊𝑝 − 𝐴𝑓𝑟.𝑓𝑜𝑟𝑐𝑒
𝐴𝑒𝑙 = 5,4𝐽 − 3,37𝐽 = 𝟐, 𝟎𝟑𝐉
𝐴𝑒𝑙 = 5,4𝐽 − 3,5𝐽 = 𝟏, 𝟗𝐉
These results were obtained on the
basis of length measurement and
calculated potential energy.
Then we measured the amount of
electricity we actually got in each case.
Results
The voltage on the capacitor in dependence on a diode type
10
9
8
7
Umax [V]
6
5
basic diode
LED
4
3
2
1
0
1
2
3
No. of measurements
4
5
Results
The capacitor's electricity in dependence on a diode type
0.45
0.40
0.35
W kon. [J]
0.30
0.25
basic diode
0.20
LED
0.15
0.10
0.05
0.00
1
2
3
No. of measurements
1
𝑊𝑒𝑙 = ∙ 𝐶 ∙ 𝑈 2
2
4
5
Results
The voltage on capacitor in dependence on the capacitor‘s capacity
10.00
9.00
8.00
7.00
Umax [V]
6.00
5.00
LED
4.00
basic diode
3.00
2.00
1.00
0.00
0.01
0.02
0.03
C [F]
0.04
Results
The amount of electricity in dependence on the capacitor's capacity
1.60
1.40
W kondenzatorja [J]
1.20
1.00
0.80
basic diode
LED
0.60
0.40
0.20
0.00
0.01
0.02
0.03
C [F]
0.04
Results
• The results of the circuit by a simple diode are
better, because the basic diode consumes less
power.
• By increasing the capacitor‘s capacity we can
store more electricity. The amount of stored
electricity also depends on the braking
distance.
Literature
[1] Tesla motors, available at http://www.teslamotors.com/
[2] List of electric cars currently available, available at
http://en.wikipedia.org/wiki/List_of_electric_cars_currently_available
[3] How Does Regenerative Braking Work? Available at
http://www.carsdirect.com/green-cars/how-does-regenerative-braking-work
[4] Regenerative brakes, available at
http://en.wikipedia.org/wiki/List_of_electric_cars_currently_available
[5] The Kinetic Energy Storage, available at http://www.youtube.com/watch?v=ZHgN1Qv9LU
[6] Regenerative braking, available at
http://www.cyberphysics.co.uk/topics/energy/regenerative_braking.htm
[7] What is the regenerative braking system?, available at http://www.alke.com/brakeenergy-recovery.html
Thank you for
your attention.