The document describes a study of an Integrated Bi-directional Flyback Converter (IBFBC) for interfacing renewable energy sources, energy storage, and loads. The IBFBC allows both charging and discharging of a supercapacitor module from a 24V DC bus. Simulation results show the converter can charge the supercapacitor from 0V to 48V and regulate the output voltage. However, the converter becomes unstable after a 27% drop in the supercapacitor voltage, limiting its ability to fully discharge the storage. Further improvements are needed to enhance the converter's performance.

1. XIV INTERNATIONAL CONGRESS OF THE
MEXICAN HYDROGEN SOCIETY CANCUN 2014
By:
J. M. Sandoval Cancino, I. Domínguez Ibarvo, D. E. Pacheco Catalán,
Y. Verde-Goméz, J. L. Durán Gómez

2. Content
 Introduction
 Methodology
 Converter description
 Results and discussions
 Conclusions

3. Introduction
 Hybrid Renewable Energy Systems (HRES)
 Intermittency Issues
 Energy Storage Systems (ESS)
 Batteries
 Supercapacitors (SC)
 Fuel Cells(FC)
 Compressed Air
 Interconnection via Integrated Bi-directional Flyback
Converter (IBFBC)

4. Hybrid Renewable Energy System
Wind
Turbine
Photovoltaic
module
DC-DC DC-DC
+24Vdc Bus
DC-DC
DC Load
Energy
management
DC Load DC-AC
AC Load
127Vac
Supercapacitor stack Batteries
IBFBC

5. Figure 1. Schematic of the proposed Integrated Bi-directional Flyback
Converter topology
Methodology
Description of proposed converter

6. Methodology: Converter description
Topology:
Bi-directional Flyback converter
Initial Data:
 Vd= +24Vdc (DC Bus Voltage)
 Vo= +48Vdc (Supercapacitor Maximum Voltage)
 Emax= 2.48 Wh/kg (Supercapacitor Maximum Energy)
 SCcap=165F

7. Methodology: Description of proposed convert
 Transformer
 N1=N2=63
 Lm=2.63mH
 S1 and S2 Duty Cycle (d):
 d1=67%
 d2=33%
 Switching Frecuency:
 20000Hz

8. Methodology: Converter description
 Duty-cycle for S1 and S2 switches:
 Voltage in S1 and S2 IGBT switches:
 Voltage in Diodes D1 and D2:

9. Interconnection strategy
Source
24V DC
Bus
IBFBC Supercapacitor module
Energy
Management

10. 80
40
8
4
80
40
10
Figure 2. Integrated Bi-directional Flyback Converter charge
operation (+24Vcd-+48Vcd) D2 and S1wave forms simulation in
PSIM™
Results
0
Vdiodo 2
0
Idiodo 2
0
Vsw1
0.19465 0.1947 0.19475 0.1948 0.19485 0.1949
Time (s)
0
Isw 1
Current (A) Voltage (V) Current (A) Voltage (V)

11. Results
40
0
Vdiodo1
3
2
1
0
Idiodo 1
80
40
0
Vsw 2
0.2796 0.27965 0.2797 0.27975
Time (s)
2.5
0
Isw 2
Figure 3. Integrated Bi-directional Flyback Converter discharge operation
(+48Vdc-+24Vdc) D1 and S2 wave forms simulation in PSIM™
Current (A) Voltage (V) Current (A) Voltage (V)

12. Results
Figure 5. S1 voltage (blue), S1 current (cyan), D2 current (pink) and 63%
Pulse Width Modulation signal (green) during charge operation.

13. Figure 4. 33% Pulse Width Modulation signal (blue), D1 current
(cyan), S2 current (pink) and S2 voltage (green) during discharge
operation.
Results

14. Figure 6. Supercapacitor module 0Vdc - +48Vdc charge via the
Integrated Bidirectional Flyback Converter graphic
Results
Time (s)
Voltage (V)

15. Output voltage
50 48 46 44 42 40 38 36 34 32 30
25
20
15
10
Output voltage (V)
Input voltage (V)
Results
Figure 7. +24Vdc output vs +48Vdc input control voltage response

16. Conclusions
 The IBFBC is a simple bidirectional topology that
requires few components reducing costs an energy losses.
 This Converter can be used to charge and discharge a
supercapacitor module with a single device.
 The IBFBC becomes unstable after 13V (27%) drop in
supercapacitor terminals, and hence cannot reach deep
discharge cycles.
 Further enhancements are required for better performances
and full topology potential.

17. Acknowledgments
 CONACYT FOMIX Qroo-2011-001-174895, under Grant
BS123CONACYT No. 280955.
 CICY for the movility economical support granted
 SMH for the conference scholarship
 Centro de Investigación Científica de Yucatán A.C.
 Instituto Tecnológico de Chihuahua
 Instituto Tecnológico de Cancun
 Dr. Ysmael Verde Gómez
 M.C. Enrique Escobedo
 M.C. Isaias Dominguez Ivarbo