Optimising the performance of a smart

electric car

Authors: Pia Žnidaršič, Tina Rejc, Mitja ŽeleznikMentor: Tomaž Kušar

Chargingwireless charging

solar panelsregenerative 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

video clip: our experiment

𝜂 [% ]=𝐴𝑒

𝑊𝑝

ResearchWe tried to find out an answer to the question: how to improve the electric car‘s efficiency?

1. We compared a basic diode and light emitting diode.

2. We also used different capacities of a capacitor.

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).

Measurements

Then we measured the amount of electricity converted from kinetic energy by the DC motors (generators).

𝑊 𝑝=𝑚∙𝑔 ∙ h

𝑊 𝑝=𝐴𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝑎𝑙 𝑓𝑜𝑟𝑐𝑒1

braking distance

𝑥1………𝑏𝑟𝑎𝑘𝑖𝑛𝑔 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒, while regenerative braking system was used

-

𝑊 𝑝=𝐴𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝑎𝑙 𝑓𝑜𝑟𝑐𝑒2+𝐴𝑒𝑙

𝜂 [% ]=𝐴𝑒

𝑊𝑝

𝐴 𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝑎𝑙 𝑓𝑜𝑟𝑐𝑒 2=𝑥2𝑥1∙𝑊𝑝

Results𝐴𝑒𝑙=𝑊 𝑝−𝐴 𝑓𝑟 . 𝑓𝑜𝑟𝑐𝑒

𝐴𝑒𝑙=5,4 𝐽 −3,37 𝐽=𝟐 ,𝟎𝟑 𝐉

𝐴𝑒𝑙=5,4 𝐽 −3,5 𝐽=𝟏 ,𝟗 𝐉

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

1 2 3 4 50

1

2

3

4

5

6

7

8

9

10

The voltage on the capacitor in dependence on a diode type

basic diodeLED

No. of measurements

Umax

[V]

Results

1 2 3 4 50.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

The capacitor's electricity in dependence on a diode type

basic diodeLED

No. of measurements

W k

on. [

J]

𝑊 𝑒𝑙=12∙𝐶 ∙𝑈 2

Results

0.01 0.02 0.03 0.040.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

The voltage on capacitor in dependence on the capacitor‘s capacity

LEDbasic diode

C [F]

Umax

[V]

Results

0.01 0.02 0.03 0.040.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

The amount of electricity in dependence on the capacitor's capacity

basic diodeLED

C [F]

W k

onde

nzat

orja

[J]

• 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.

Results

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=ZHgN1-Qv9LU

[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/brake-energy-recovery.html

Thank you for your attention.