1. Fuel cell development program for electric vehicle
The Hong Kong Polytechnic University
EE4006A Individual Project
Fuel cell development program for electric vehicle
Name: CHIM Kwan Kit
Student ID: d
Supervisor: Dr. K. W. Cheng
Department: Electrical Engineering

2. Content Introduction Objectives Methodologies Results Conclusion
Al-air battery
Boost-converter
PWM
Regenerating system
Results
Conclusion

3. Introduction Hybrid and electric vehicle are the trend
Many vehicles companies are starting to analyze hybrid and electric vehicles (e.g. Phinergy, Toyota)
The environmental batteries used now are AlO and ZnO
The project included
Power processing
Energy conversion
Battery analyzing

4. Objectives Primary goals:
Find a control method to control power processing
Find a optimization of the battery
Apply on electric vehicles successfully
Secondary goals:
Have a contribution to the environmental work
Encourage people to start using electric vehicles

5. Methodologies- Board diagram

6. Methodologies- Al-air battery
Characteristic of Aluminum-air battery
High energy density (8kWh/kg)
High power and service hour
Non-rechargeable

7. Methodologies- Al-air battery
The electrochemistry of aluminum-air battery
Anode: Al + 3OH− → Al(OH)3 + 3e− -2.3 V
Cathode: O2 + 2H2O + 4e− → 4OH− V
Total reaction: 4Al + 3O2 + 6H2O → 4Al(OH)3  V

8. Methodologies- Al-air battery
Some factors affecting battery performance
Voltage level
Current drain of discharge
Temperature of battery during discharge
Different material and concentration of electrolyte
Service life

9. Methodologies- Al-air battery
Producing an Al-air battery
Carbon electrode part
Cut the barbed wire to the shape that fits the size of the plastic case
Wrap the barbed wire around iron mesh to give a better contact with the carbon
Separate large activated carbon by using sieving
Shake carbon granules to uniform layer
Mix epoxy glue
Add carbon granules into the glue and stir
Strew and smear the mixture
Shake carbon granules to both sides in order to make sure the electrode full of carbon
Put the electrode under high pressure
Make sure the electrode is low resistance in order to reduce loss

10. Methodologies- Al-air battery
Producing an Al-air battery
Battery part
Make two carbon electrodes from the previous procedure
Place the carbon electrodes together with the aluminum foil at the middle into the plastic case
Use the butter paper to separate the electrode and the aluminum foil
Test by using multi-meter (check the resistance) that there is no short circuit between the electrode and aluminum foil
Use measuring bottle to make certain volume of solution
Add the solution into the plastic case
Test the no load voltage and current to make sure the battery is work.

11. Methodologies- Boost converter
The reasons using boost converter:
High output voltage
Fast transient response
High efficiency
Economical

12. Methodologies- Boost converter
The input/output voltage ratio:
Vin(DTs) = (Vo – Vin)(1 – D)Ts
𝑉𝑜/𝑉𝑖𝑛 = 1/1−𝐷 (𝑉𝑜 > 𝑉𝑖𝑛)
Power relationship:
VinIin = VoIo

13. Methodologies- Boost converter
Design of boost converter

14. Methodologies- Pulse-width modulation (PWM)
Function of PWM
Encoding message into a pulsing signal
Controlling the voltage supply to electrical devices
Advantages of PWM
Low switching power loss
Little heat whilst working
Efficiency up to 90%

15. Methodologies- Pulse-width modulation (PWM)
Design of PWM

16. Methodologies- Pulse-width modulation (PWM)
NE555 is used
Frequency = 1.44 / ( RA + 2RB ) C
Output driver duty cycle = tL / ( tH + tL ) = RB / RA + 2RB
Output wave form duty cycle = tH / ( tH + tL ) = 1 - RB / RA + 2RB
Low to high ratio = tL /tH = RB / RA + RB
RA = 1k + 20kΩ, where 20kΩ is a variable resistor.
RB = 6.2kΩ

17. Methodologies- Regenerative braking
A regenerative brake is an energy recovery mechanism
When the car is on load or braking, the motor would act like a generator to generate reverse energy flow in backward direction.
Advantage of regenerative braking
Increase efficiency of the system

18. Results- Al-air battery

19. Results- Al-air battery

20. Results- Al-air battery

21. Results- Al-air battery
Aluminum foil in 5M NaOH solution
Aluminum foil in 2M NaOH solution

22. Results- Al-air battery

23. Results- Al-air battery

24. Results

25. Results
Duty cycle of the 17.1%
Duty cycle of 25.6%

26. Results- Regenerative braking

27. Conclusion Al-air battery
The solution using KOH is better than using NaOH with higher power generated
Voltage and current generated would be increased when the concentration increased
The lifetime of the battery is based on the aluminum corrosion rate
Different connection can affect the performance of the battery
The numbers of the carbon electrodes affects the amount of the current

28. Conclusion Boost converter and PWM Regenerative braking
output voltage > input voltage
Duty ratio is changed by the variable resistor
PWM plays the role of controller
Output voltage affects the speed of the motor
Regenerative braking
A capacitor is used to store the energy
one more MOSFET has to be used