1. Close-to-production System Controller using Raspberry Pi and TinkerForge Hardware for an SOFC-APU
Dipl.-Ing. Christian Szepanski
Chemical Power Systems
Thanks for the kind introduction Mr chairman, my name is christian szepanski and i would like to present some of our work that we did in the framework of the sapiens project. i would also like d to thank my coauthors who contributed to this.
Coauthors: Dipl.-Ing. Yiyang Su
Dipl.-Ing. Oliver Keich
Dr.-Ing. Andreas Lindermeir

2. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
Overview
CUTEC – Introduction
SAPIENS – Project
System Concept
Hard and Software Solutions
First Results
Conclusions
This is the outline of my presentation – first i am goign to give a brief introduction to the CUTEC institute – Then i am going to explain what the sapiens project is about.

3. We are an everinmental technology institute Funded by the local government.

4. Sustainable Industrial Society
FDFC Raspberry Pi and TinkerForge System Controller
CUTEC - Business Segments
Natural Resources
Sustainable Industrial Society
Energy
Resources
Chemical
Power Systems
Thermal
Process Tech.
Waste-water Eng.
Metal Recycling
SOFC
Information
Enviromental institute
Energy Systems Analysis
Public research institute
100 employees
Application oriented R&D 4

5. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
SAPIENS – Project
Project aims to design a mSOFC APU with LPG as Fuel
Integration into RV (or mobile home)
SOFC
Auxiliary 
Power In
Emissions/
Noise 
Solutions
This project aims to design, optimise and build several mSOFC (microtubular solid oxide fuel cell) stacks and to integrate them into hybrid power systems comprising a fuel cell, battery and appliances found in a recreational vehicle (RV, or mobile home).
For more details please check:

6. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
System Concept
Filter (air intake)
Exhaust
Fuel inlet
Controller
Hot Box
150 mm
Air blower
Valve
450 mm
Casing: 450 mm (from 300 mm)
Air is sucked in the casing and pumped into the stack/Hotbox. Part of the air is mixed with the LPG for the cpox (just behind the fuel inlet)
Valve (and flow meter, behind it): We are developing our own MFC – cheap and power saving
200 mm 6 6

7. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
Electric Circuit Diagram
Charger
(<20 A)
To BoP-components
(parasitic consumption)
24V converter
(< 6 A)
Stack
(12-20 V)
Load resistor
(~4 Ohm)
24V U U U I I
Battery
12 V
12V
For TF and RP *
To RV
Revised version of the Circuit Diagramm with Fuses Relays, switches, Voltage- and Current meters
TF = Tinkerforge
RP= Raspberry Pie = µ-PC
Fuse
* TF = Tinker Forge
RP = Raspberry Pi I

8. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
TinkerForge Test Bench
Solar Charger µ-PC Power electronics Sensors and actuators User-Interface
Python

9. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
User Interface for RV-User
LC-Display with button control – different modes 9 9

10. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
User Interface (Developer Interface / not for RV-User)

11. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
Start/Stop Routine
Start
Self-check:
Air and LPG pressure
„Ignition“  mix 0
y/n
Heating w/ mix 0  mix 1  mix 1/3
Temperature and Voltage ok?
STOP
Battery full?
Disconnect Charger
SHUTDOWN
Timer
Standard Operation
Resistor OFF
Connect Charger
Resistor ON

12. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
Control Algorithm incl. Part Load (1/3, 2/3, 3/3 Power)
Idealized U/I-chart for 16 cell stack:
20V
1/3 of maximum LPG
2/3 of maximum LPG
3/3 of maximum LPG
14V 4A
56W 6A
84W 8A
112W
Adapting flow rate of LPG to measured power demand
If more LPG is supplied to stack, OP will change to a higher U/I curve
Charger takes all available current at charging voltage (≥ 14 V)

13. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
Standard Operation
Current?
Charging with part load 1/3
Resistor on
3-5A
<3A
>5A
Charging with part load 2/3
5-7A
<5A
>7A
Charging with full power
≤7A
>7A

14. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
Cathode Air Control Routine
Air-fuel ratio for Charging with part load (1/3)
Air-fuel ratio for Charging with part load (2/3)
Air-fuel ratio for Charging with full load (3/3)
Power Mode changed ?
y/n
Temperature ?
Increase Airflow
> 650°C
< 600°C
Decrease
Airflow °C

15. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
BoP Power Consumption
Device
Supplier
Supply [V]
Rated Current [mA]
No. of Units
Standby
[W]
Operation
Flow Sensors
Posifa 5 25 3
0,4
Raspberry Pi B+
Rasp. Pi Found.
500 1
2,5
TinkerForge 50
10-20
0,2
DC/DC 12->24V
OSKJ 12 14
Solar Charger
IVT 20
Pressure Sensor
First Sensor 24 23 4
2,2
Valve (LPG)
Bürkert 83
2,0
Valve (air)
ASCO Numatics
250
6,0(*)
Cathode Blower
ebm-papst
0-1700
~18  S
≤ 3 34 S
Controller Hardware   
(*) Consumption in steady state conditions = 1W

16. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
Start up
Power consumption
during startup:
≤ 21W
Accidental switch off of 24V supply w

17. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
Charging and Power Distribution
discharging
charging
Air blower set to maximum
Battery power < 0: charging

18. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
Summary and Outlook
Controller hard- and software have been built, programmed and tested
Low power consumption in operation and standby
Automatic power management and distribution
Combination of mass produced hardware and python programming is costs and time saving
Next steps:
Adjustment of control routines to real life
Improvements of response times
Further reduction of parasitic consumption
Long term tests of the complete system in different conditions 18

19. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
Acknowledgements
SAPIENS is funded under Europe’s Fuel Cell and Hydrogen Joint Undertaking (FCH JU) for 36 months, from November 1, 2012: Grant Agreement No
The consortium gratefully acknowledges the support of FCH JU.

20. “What´s on telly tonight?“
SAPIENS Meeting
Byebye slide
“What´s on telly tonight?“ 20

21. FDFC 2015 - Raspberry Pi and TinkerForge System Controller
Tinker Forge Test bench next gen.
Revised version of the Circuit Diagramm with Fuses Relays, switches, Voltage- and Current meters
TF = Tinkerforge
RP= Raspberry Pie = µ-PC 21 21