Design and Implementation of High Resolution Data Acquisition System

IJSRD - International Journal for Scientific Research & Development| Vol. 1, Issue 7, 2013 | ISSN (online): 2321-0613
All rights reserved by www.ijsrd.com 1417
Abstract— Fuel cell stacks containing hundreds of
individual cells are capable of generating high voltage and
current values needed for transportation, commercial,
residential, portable and industrial power applications.
Although majority of hydrogen produced today comes from
reformulated natural gas generated through a process that
creates a significant amount of carbon dioxide, fuel cell is
still a viable energy source for the future electrical power
applications.
One of the hard cases of the fuel-cell power systems is
proper monitoring, instrumentation and data acquisition of
system parameters such as fuel flow into the system, AC and
DC voltage values, load current, humidity, power, pressure,
temperature, fuel utilization, overall system efficiency,
noise, etc. Fuel cell test systems must precisely monitor and
control the aforementioned hundreds of measurements in
real-time. It is necessary to have an instrumentation system
which is able to monitor and control fuel cell operation
under varying conditions and accurately get information
relating to real-time performance and operational
characteristics to calculate fuel cell efficiency correctly.
Instrumentation and interface systems must also provide
flexible data acquisition, monitoring, and control capability
to precisely control fuel cell operation. Therefore, a typical
fuel cell test system requires high-resolution, high-voltage
input, isolation, and waveform acquisition capability. The
objective of this applied research project is design and
implementation of a high-resolution data acquisition and
interface module for a 500 W Hydrogen fuel cell power
station using LabVIEW™ PDS v8.20 software and field
point based data acquisition modules.
Keywords: Simulation, Resolution Modeling, Fuel Cell,
Control, Data acquisition.
INTRODUCTIONI.
In this study, a fuel cell data acquisition and monitoring
system is designed implemented and tested. It consists of
three main parts; a fuel cell power station, data acquisition
hardware tools, and a LabVIEW installed computer as
shown in Figure 1. These three main parts make the overall
data acquisition system is capable of measuring AC/DC
voltage, current, produced and consumed power,
temperature, gas pressure, H2 gas consumption and overall
efficiency in real time.
The proposed fuel cell data acquisition and monitoring
system makes a variety of measurements that require signal
conditioning before the raw signal can be digitized by the
data acquisition system. Signal conditioning handles the
conversion of current, pressure, and temperature to voltages.
In this study, National Instruments Compact Field Point and
modules were used for data acquisition measurement and
monitoring. Signal data collected from AC/DC voltage and
current transducers, flow meter, and thermocouple
processing in the Field Point.
Fig. 1: Data acquisition and monitoring system phases
Test systems that have the ability to make all pertinent
measurements while providing the flexibility to work with
new procedures and calculations are critical; therefore PC
technology was used with Field Point platform. Besides,
LabVIEW (Laboratory Instrument Engineering Workbench)
software is used for data logging. Both LabVIEW and Field
Point are standard products of National Instruments that
provide precise data acquisition.
Also, LabVIEW has prosperous graphical interface that
provides monitoring all variable at the same time
numerically and graphically simultaneously.
Before starting measurement and monitoring experiments,
three main parts of the system will be explained. EPAC-500
fuel cell station is stand-alone station that consists of fuel
cell stack, microprocessor, and air pump, cooling fans,
hydrogen purge solenoid valve, single stage pressure
regulator, filter, power connector, start-up connector and
current and voltage transducers. Gas flow meter is mounted
between gas tank and the fuel cell power station. As shown
in Figure 1, Fuel cell power station connected with data
acquisition and monitoring part.
Second part of the system is data acquisition and
monitoring part. It contain 8-channel thermocouple input
module, 8-channel analog voltage and current input module,
rugged intelligent Ethernet controller interface for compact
Field Point, integrated connector block for wiring, 8-channel
analog voltage and current input module. All these tools are
produced by the same company, National Instruments, so
they are compatible with each other and work successfully.
After formulating necessary variables such as gas flow,
current, voltage, power etc., LabVIEW program is created.
Then using oscilloscope program accuracy was tested by
Instruments, so they are compatible with each other and
work successfully.
Third part of the system is LabVIEW installed computer. This
part connected with data acquisition and monitoring part as
shown in Figure 1. LabVIEW is a graphical programming
language that uses icons instead of lines of text to create
Design and Implementation of High Resolution Data Acquisition
System
B. M. R. Manasa1
K.Venkatesh2
1
M.Tech 2
Asst. Professor, Department of ECE
1,2
Siddharth Institute of Engineering & Technology, Puttur

Design and Implementation of High Resolution Data Acquisition System
(IJSRD/Vol. 1/Issue 7/2013/0011)
Vin Iin VSUP COM
Measured
Data
Output
CHANNEL
0
1 2 17 18
AC
Voltage(V)
0-20
mA
CHANNEL
1
3 4 19 20
AC
Current(A)
0-20
mA
CHANNEL
2
5 6 21 22
DC Voltage
(V)
0-5 V
CHANNEL
3
7 8 23 24
DC Current
(A)
0-5 V
CHANNEL
4
9 10 25 26 Flow Rate 0-10 V
CHANNEL
5
11 12 27 28
Thermo
couple (F)
0-10V
Table. 1: Demonstration of DAQ system channels
Fig. 2: EPAC-500 hydrogen fuel cell power system
application. In LabVIEW, a user interface can be built by
using a set of tools and objects
After making sure that whole system parameters work
successfully, an experimental procedure on the system is
done. The following procedure is outlined for the test–set
system. The photograph of the overall hydrogen fuel cell
data acquisition system is depicted in Figure 2.
DATA ACQUISITION SYSTEMII.
The analog and continuous time signals measured by the
transducers must be converted into the form that a computer
can understand. This is what is referred to as data
acquisition as shown in Figure 3. Conventionally,
measurements are done by various types of stand-alone
instruments like oscilloscopes, digital and analog multi
meters, counters etc. However, the necessity to save the
measurements and process the gathered data for
visualization has become very important for reliable and
efficient fuel cell power station (FCPS) operations.
Fig. 3: Data acquisition system
A. Number of Input channels
The Field Point gives out 8 channel of information. So a
data acquisition (DAQ) board with 6 input channels was
selected. Channels start from 0 to 5. Table 1 shows
measured data and other characteristics of data for each
channel.
And corresponding data information used in the FCPS data
acquisition
B. Hardware Selection
Data acquisition cards that can be connected to PC-
computer provide cost-effective high-speed multi-channel
analogue inputs. The Compact Field Point is suitable for
measuring voltages in ranges ±0.05V to ±42V. The
sampling rate is 1.25Ms/channel with a 16-bit resolution.
C. MKS 179A Mass-Flo Type Mass Flow Meter
The MKS Instruments 179A Mass-Flo® All-Metal Mass
Flow Meter (MFM) as seen in Figure 4 is a mass flow meter
(MFM) designed to measure the flow of gases in a wide
variety of applications.
SOFTWARE DESINGIII.
The DAQ hardware without appropriate software is of little
use. The purpose of having appropriate software is the
following:
1. Acquire Monitoring and simultaneously processing
data in real time.
2. Controlling the test
3. Generating reports in variety of graphical formats
4. Stream data to and from storage device.
5. Use various functions of a DAQ board from a
single user interface
6. Real Time Display
A. Software Tools under consideration.
1 Microsoft’s Visual C++ environment
2 Matlab
3 Nation Instruments LabVIEW
The advantages and disadvantages of which are listed in
Table 2
Comparison
Characteristic
Matlab® VC++ LabVIEW
Hardware
Support
Needs Third
Party
Drivers
Interface
libraries
provided
Direct
Support
Speed
Slower than
VC++ but
faster than
LabVIEW
Fastest Slowest
User
Interface
Easy, Drag
and Drop
Very
Complicated
Easy, Drag
and
Drop
Modular
Programming
Possible, with
little
Tweaking
Possible,
with
little
tweaking
Easiest
Learning
Curve
Slow Slow Fast
Table 2. Comparison of various software design
environments
NI LabVIEW, short for Laboratory Virtual Instrument
Engineering Workbench, is a programming environment.
National Instruments LabVIEW is a graphical programming
language that has been widely adopted throughout industry,
academia, and research labs as the standard for data
acquisition and instrument control software [1]. LabVIEW
departs from the sequential nature of traditional
programming languages and features an easy –to-use
graphical programming environment, including all of the
tools necessary for data acquisition (DAQ), data analysis,

and presentation of results [2]. The LabVIEW data logging
and supervisory control module from NI meet the needs of
fuel cell researchers with its built-in high-channel-count data
acquisition, data logging, interface, and security capabilities
[3]. Fuel cell test systems may require many data acquisition
sensors and controls for temperature, humidity, atmospheric
pressure, oxygen, and other parameters. Figure 5 and 6
depict the interface and the automation software block
diagram of the LabVIEW respectively. NI Field Point
measurement and automation explore software to collect
data from channels in the DAQ board of the FCPS. The NI
data acquisition modules are placed between computer and
fuel cell system to convert analog input to digital output for
the field point measurement. NI measurement and
automation software recognizes channels of the data
acquisition models such as voltage, current, temperature,
and mass gas flow.
OVERALL SYSTEM FUNCTIONAL DIAGRAMIV.
H2 PEM fuel cell stacks are fed by hydrogen (H2) metal
hydride storage container as shown Figure 7. H2 inlet has a
pressure regulator installed in the container. This regulator
adjusts the incoming hydrogen pressure. Between fuel cell
stacks and H2 inlet there is a H2 mass flow meter. An
External power supply provides electricity to the flow meter
at 15 V voltage range. Mass flow meter obtains analog data
about gas consumption and transmits data to the AC/DC
analog module (cFPAI-100). The Oxygen (O2) amount
required for fuel cell system is provided directly from air.
For this purpose, the system has 3-6 psi DC air pump as
seen in Figure. The fuel cell stack is equipped with a low
pressure particulate filter on the reactant air inlet to prevent
airborne materials and contaminants from entering the stack.
Hydrogen fuel cell system shown Figure 7 has three outlets.
These are H2 O outlet, H2 outlet, and purge outlet. H2O
outlet drains water vapor which is formed from chemical
reaction between H2 and O2. H2 outlet ventilates over-
pressed gas.
Fig. 5: Fuel cell data acquisition system LabVIEW interface
There is a H2 recirculation system between H2 outlet and
H2 inlet which gathers unused H2 and conveys to the fuel
cell stacks. As the hydrogen is used within the fuel cell,
water and other contamination build up until they block the
hydrogen flow to the stack. Periodically a solenoid valve is
opened to allow the water and any contaminations to be
purged from the fuel cell stack by purge outlet. The fuel cell
system is equipped with cooling fans. The operation of fuel
cell generates heat. If this heat is not removed, the operation
of the stack may will become inefficient and leading the
overall system to halt.
Fig.6 Fuel Cell data acquisition system LabVIEW block
diagram
Fig.7 Hydrogen fuel cell system functional block diagram

Fuel cell system is controlled by an external control circuit.
Control circuit has a central microprocessor which monitors
and controls all of the functions that make the fuel cell
system operate in a stable condition. It process system
parameters such as stack temperature, current, voltage, etc.
It controls air pump speed, hydrogen purge, cooling fan
operation and on/off requirements. The volume of air
delivered via air pump is controlled by a microprocessor
proportional to the amount of current being delivered by the
fuel stacks. Power required for microprocessor and solenoid
initiation and operation is supplied externally to the fuel cell
system. In the fuel cell stacks, voltage induced in every
single stack is combined together and transmitted to the
control circuit. Between stacks and control circuit, there are
DC current and voltage transducer which are connected to
the AC/DC analog input module (cFP-AI-100). Since the
electrical power derived from fuel cell stacks is not constant,
control circuit regulates the voltage and outputs
corresponding DC current to the DC to AC inverter. An AC
power inverter converts the DC voltage to the AC voltage in
the range of 42V to 65V AC values to the load. There is AC
voltage and current transmitter between DC to AC power
inverter and AC output which are connected to the analog
input module (cFP-AI-100). Another AC/DC analog input
module (cFP-AI-120) connected to a thermocouple to
measure stack temperature. Other end of the thermocouple is
connected to the fuel cell stack. All analog input modules
are mounted to the NI Compact field point module (CFP-
2020). NI Compact field point is energized by an external
power source. It is connected to a PC with Ethernet
connection. A LabVIEW 8.2 with Measurement Studio as
data acquisition software has been installed in the computer
used in the overall instrumentation system.
VERIFICATION & TESTINGV.
A. Cost of the Data Acquisition System
The cost of the system depends on the application and NI
software/data acquisition tools. The EPAC 500 Fuel Cell
Power Station and NI data acquisition modules were
donated by National Instruments. The software tools NI
LabVIEW Version 8.20, additional NI data acquisition
modules, MKS mass flow meter, and few connectors and
cables were purchased. Besides, depends on hydrogen use,
four hydrogen tanks are regularly refilled for the system
operation. The time to set up the system including ordering
additional software and hardware tools, rewiring, comply
interoperability of the devices and software tools is about
two and half months. Value of the parts is shown in Table 3.
Cost of data acquisition is $5,805. With more than %99
accuracy this data acquisition system is very low-cost
system compare to commercially available data acquisition
system.
B. Accuracy of the Data Acquisition System
Accuracy of fuel cell data acquisition system tested with 5
case studies. FCPS loaded with no load, 50W, 100W, 150W,
200W loads in these cases. For each case study, AC
voltage/current, DC voltage current, AC/DC power and
temperature measured with both data acquisition system and
multimeter. The tables for each case study are shown
respectively with Table 5, 6, 7, 8, and 9.
As it shown in Table 5, some of data such as AC current,
DC current, DC power are same for both measurement
methods. DC and AC voltages for both methods are very
close each other. Case 1 shows that data Acquisition system
has %99- %100 accuracy.
Part/Software Unit Price
EPAC 500W Power Station 1
$14,000
(donated)
NI LabVIEW v 8.20
Developer Suite -
Research
1 $2,400
MKS 179A Mass-Flo® Mass
Flow Meter
1 $920
cFP-AI-100, Data Acquisition
Module
1
$120
(donated)
cFP-TC-120, Data Acquisition
Module
1
$140
(donated)
cFP-2020, Field Point 1
$240
(donated)
cFP-AI-112, Data Acquisition
Module
1 $610
Hydrogen Fuel Tanks 4 $360
Dell Computer 1 $950
Ethernet Networking cable 1 $25
Field Point Connectors 2 $40 (donated)
Cost of data Acquisition System $5,805
Total $19,805
(including
donation)
Table. 3: Cost of the Hydrogen Fuel Cell System
DC DC AC AC DC AC
No load Voltage Current Voltage Current Power
Powe
r
(V) (A) (V) (A) (W) (W)
Data
acquisition 56.54 0.32 121.65 0.02 18.09 2.16
system
Multimeter 56.53 0.32 121.63 0.02 18.09 2.16
Correlation %99.46 %100 %99.96 %100 %100
%10
0
Table. 4: Case Study 1 (No Load)
DC DC AC AC DC AC
Measurement
s
Voltag
e
Curren
t
Voltag
e
Curren
t
Power Power
50W (V) (A) (V) (A) (W) (W)
Data
acquisition
system
53.61 1.37 121.70 0.44 76.37 53.54
Multimeter 53.58 1.36 121.65 0.43 76.94 52.31
Correlation
%99.4
4
%99.2
7
%99.9
6
%97.7
2
%99.2
5
%99.5
7
Table. 5: Case Study 2 (50w)

DC DC AC AC DC AC
Measurement
s 100W
Voltag
e
Curren
t
Voltag
e
Curren
t
Power Power
(V) (A) (V) (A) (W) (W)
Data
acquisition
system
52.21 2.44 121.84 0.87 127.39 106.00
Multimeter 52.18 2.42 121.80 0.86 126.28 104.75
Correlation
%99.9
4
%99.1
8
%99.9
5
%98.8
5
%99.1
3
%98.8
2
DC DC AC AC DC AC
Measurement
s
Voltag
e
Curren
t
Voltag
e
Curren
t
Power Power
150W (V) (A) (V) (A) (W) (W)
Data
acquisition
system
50.18 3.57 121.70 1.27 179.14 154.56
Multimeter 50.14 3.56 121.64 1.26 178.50 153.27
Correlation
%99.9
2
%99.7
2
%99.9
6
%99.2
5
%99.2
4
%99.2
2
DC DC AC AC DC AC
Measurement
s
Voltage
Curren
t
Voltag
e
Curren
t
Power Power
200W (V) (A) (V) (A) (W) (W)
Data
acquisition
system
50.62 4.68 121.94 1.71 236.90 208.51
Multimeter 50.53 4.64 121.89 1.68 234.92 204.77
Correlation %98.22
%99.1
4
%99.9
6
%98.2
5
%98.9
9
%98.2
0
Case 1
Case
2
Case
3
Case
4
Case 5
Temp (
0
F )
No Load 50W
100
W
150
W
200W
Data
acquisiti
on
system
77.6 92.06
121.
35
112.
46
121.87
Multimet
er
77.8 92.10
121.
40
112.
51
121.92
Correlati
on
%99.74
%99.
96
%99
.96
%99
.96
%99.96
Table. 9: Temperature Values Measured By Multimeter and
Data Acquisition System
As shown in Tables, data acquisition system`s temperature
has %99.74 or more correlation close multimeter`s
temperature values. All case studies show that data
acquisition system measurements have % 99 correlations
With multimeter correlation.
C. Data Acquisition System Interface
Developed data acquisition system has graphical interface.
As shown in Figures 8 user can monitor FCPS variables
both graphically and actual data.
Fig. 8: Data acquisition interface with 50W load
CONCLUSIONSVI.
Fuel cell technology is still in its developing period.
Although it has application in many diverse areas, it needs a
lot of equipment to be more preferable technology for
consumers. Having low cost, user friendly and portable
measurement and monitoring system is one of them. In this
study, data acquisition, measurement and monitoring system
developed for 500W, EPAC-500, portable fuel cell power
system. Works have done for this study can be divided three
main parts. These are hardware design, software design and
implementation parts.
Data acquisition, measurement and monitoring system
essentially needs transducers for each variable, analog input
module, and digital output modules to construct hardware
part. EPAC-500 has its own transducers for AC/DC voltage,
AC/DC current temperature. Mass flow meter MKS 179A
mass-flow was selected to as a mass flow meter to measure
gas consumption. National Instrument`s Field Point and
modules were chosen as analog input modules and analog to
digital signal converter as shown in Table 10.
Measurement
Channel
Type
Signal
Conditionin
g
Field
Point
Modules
Voltage
Analog
Input
Isolation,
Attenuation
cFP-AI-100
Current
Analog
Input
Scaling,
Attenuation
cFP-AI-100
Temperature
Analog
Input
Scaling,
Amplificati
on
cFP-TC-120
Compact
Field Point
Analog
Input
Digital
Output
cFP-2020
Hydrogen
Flow Rate
Analog
Input
Scaling,
Attenuation
cFP-AI-112
Table 10: Field Point test platforms

Second important part of study is software selection and
design. Because of its high real-time performance, data
acquisition capabilities and user-friendly interface
opportunities LabVIEW was selected as software. Another
important reason to choose LabVIEW is that its high
compatibility with Field Point. Using LabVIEW tools, data
acquisition program was developed. As shown in Figure
LabVIEW program has two parts. One is block diagram
which program code had written as shown in related figure.
Other one, as shown in Figure 8, is front panel which user
can monitor variables programmed in block diagram. This
provides simplicity for both programmers and users.
RECOMMENDATIONVII.
Developed data acquisition system in this study is not able
to store data which acquired in real-time measurement and
monitoring process. Clearly, with data acquisition system
which has data storing capabilities, much more data can be
gathered more precisely in a shorter time. In this way,
changes in system variables and system performance can be
followed in a superior way. Hardware and software parts of
the system both have capability to store data with improving
written LabVIEW program with using Lab VIEW`s
Measurement and Automation tools.
As it mentioned in the limitations, data acquisition system is
limited to 500W, EPAC-500 fuel cell power station. Further
study can be done to make the system available to work with
variety of fuel cell systems.

Design and Implementation of High Resolution Data Acquisition System

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Design and Implementation of High Resolution Data Acquisition System