1、1Design of Hydrogen Concentration Realtime Detection System Based on The LABVIEW for Electric VehicAbstract. One of the important factors affecting electric vehicle safety is hydrogen concentration. It is important to guarantee electric safety for real-time detection hydrogen concentration of electr
2、ic vehicle charging and running .It designs a hydrogen concentration measurement system based on LABVIEW virtual test equipment， it can collection， analysis， display and storage hydrogen concentration of new energy electric vehicle.Finally，experiments have been conducted on valve-controlled nickel c
3、admium batteries nickel-metal hydride battery-vehicle and vehicle-and lead-acid and single battery.The results show that the detection systems can accurate display electric cars true value of concentration of hydrogen in real time， hydrogen concentration value of space will sound an alarm when limit
4、 is reached， system stability and meets the design requirements. Key words： Electric vehicles； LABVIEW； Hydrogen concentration；Detection；Real time 2Introduction With the development of automobile industry and transport transport industry，more and more automobile safety problems have been brought to
5、our attention.As the countrys “863“ plan implementation ，hybrid-powered cars， electric cars and other green energy green vehicle research and development projects have been started.Due to electric vehicle power system is a big difference with the traditional internal combustion engine vehicles， secu
6、rity implications is also different from the traditional internal combustion engine vehicles.During charging and operation， accidents may occur like collisions， rollovers and dangerous working conditions， resulting in extrusion of dynamical systems， short circuit， thermal shock， leakage， explosion，
7、burns etc. Resulting in electric mechanical injury to occupant， battery damage， injury， chemical and burn injuries and may cause a bigger fire accidents and secondary victimization1 .In the domestic， several major electric vehicles instantly burn to the ground and throughout the laboratory accident2
8、. Therefore， it is significance and practical value to test the concentration of hydrogen and electric vehicle safety technology . Many domestic and foreign scholars are study the safety 3testing of electric cars and achieve fruitful results.South Koreas BMS （battery management system） relies on the
9、 effective manage -ment the nickel-metal hydride batteries， which improves the performance installation of this battery electric vehicle safety3. 4 introduced the ZEBRA battery has reliable security features.In the crash tests， battery causing serious injury， nor cause harm to passengers. It has rel
10、iable security. Internal reference standards， a series of safety regulations for electric vehicles are released in 2001.GB/T18384.118384.3：20015 has detail provisions for vehicle safety requirements. Hydrogen concentration is important factor for EV security. If it can be detected in real time recha
11、rging and running of hydrogen concentration， you can greatly reduce the occurrence of dangerous accidents. At home and abroad have all kinds of combustible gas detection instruments.We have to develop a combustible gas detector dedicated to electric vehicles， because of structural characteristics of
12、 the trunk closed and its power source for electric vehicle charging and discharging characteristics of anti-static， fire，While such studies are still not perfect， largely blank. In the paper ，it establishes a detecting system for 4hydrogen concentration based on LABVIEW. It can detect different run
13、ning on battery electric vehicle and battery charging real-time.The results show that this system can better meet safety requirements for electric vehicles and have better value in use and application. 1. Design of Real-time Detection System for Hydrogen Concentration Detection system including sens
14、ors， transmitters， data collection card and computer，they can achieve automatic acquisition signal， analysis， display， store and alarm functions.The course are： Hydrogen gas after appropriate sensors， the sensor will measure signals transmitted over a three-core cable to the data acquisition card， a
15、fter the A/D converted to a voltage signal， then filtered、amplified signal conditioning circuits， data acquisition card into the computer， finally computer analysis、display and storage signal.Real-time detecting system for hydrogen concentration schematic diagram is shown in Fig.1： 2. Introduction t
16、o Hardware Systems Fig.2 is a hardware block diagram for real-time detecting system of hydrogen concentration， it is mainly composed of hydrogen concentration sensor， transmitter， computer 5components and data acquisition card. 2.1 sensors and transmitters Sensors detect hydrogen concentration；trans
17、mitters are hydrogen concentration sensor output signals turn signals can be recognized by the controller.Sensors and transmitters consist of a control signal source together.In the hydrogen concentration detection system， sensors and transducers form Germany OLDHAM.Sensors have many advantages like
18、 higher precision， strong anti-jamming ability and error is small.In unexpected situations， it can be collected related data.Because of pressure accumulator and temperature compensation devices. 2.2 computer and data acquisition card Computer with PC computer with a PCI slot or ordinary notebooks， s
19、oftware using WINDOWS7 operating system platform with LABVIEW software. Data is collected from sensors represent different characteristics analog signal， a charge amplifier and anti alias filter out high frequency and low frequency signals regardless of the signature and then after A/D conversion re
20、aches the computer.Grabber mainly consists of analog multi-channel switch sense circuit， analog-digital conversion 6circuits， differential amplifier circuits， the switch quantity input/output control logic circuits and interface circuits6.Desktop capture cards use the PCI slots.，ordinary laptops use
21、 the USB serial port. 3. Development of Software System LABVIEW is a virtual instrument development platform developed United States national instruments.In the LABVIEW platform，using c/c + +， ASM mixed-language programming to develope multi-channel， real-time high-speed data acquisition system，it c
22、an real-time display， real-time curve， data storage， data alarming features .System software is divided into five modules： System reset module initialization，system control module， data processing and display module， over-limit alarm module and data post-processing module7. （1） System reset module i
23、nitialization This module includes the sampling frequency of the system ， the hydrogen concentrations of alarm data size， electric power is automatically disconnected when charging is complete switch Sampling frequency and concentration of hydrogen gas alarms relies on actual requirements 8. （2） sys
24、tem control module This module is a core part of design system software， 7using LABVIEW program to call and drive data acquisition card ， and then processed and analyzed data.Data flow chart as shown in Fig.3. （3） data processing and display module Data processing and display module to store and con
25、version the hydrogen concentration data.Data is displayed in the chart ，it can be displayed in real-time and observed data size visually and effective. （4） over-limit alarm module When it detects hydrogen concentrations above the threshold concentration， system will alarm and the indicator light fla
26、shes and beeps. （5） data post-processing module The main feature of data processing module is that the system software upon completion of the work such as data collection and processing， data collected and processed data can be played back for later continuing studies10.Save and replay programs bloc
27、k diagram of data shown in Fig.4. 4. Experimental Verification of Real-time Detecting System for Hydrogen Concentration 4.1 experiment preparation According to experimental requirements， testing experiment 8should be confined indoors. Experiment using a notebook computer for data acquisition and dat
28、a processing.Sampling rate of 5 points per minute， alarm levels set 50%LEL ，installation 4-channel， three of whom are France Oldham sensors， the fourth channel as an experiment. 4.2 vehicle experiments In order to detect hydrogen concentration under the vehicle charging ， we will test into the airlo
29、ck.In order to mix cabin gas well， in the corner placement it pressurized four fans. It start charging at the same time to start testing the system， real-time monitoring hydrogen concentration in the cabin. 4.2.1 valve-nickel-metal hydride battery-vehicle testing In the pressurized cabin ，variation
30、of hydrogen concentration during charging process is shown in Fig.5. As we can see from the illustration， in charge three hours later， the hydrogen concentration in the pressurized cabin increases in size， but no alarm limit is reached. System is working properly. 4.2.2 nickel-cadmium battery-vehicl
31、e testing In the pressurized cabin ，variation of hydrogen concentration during charging process is shown in Fig.6. 9As we can see ， in charge three hours later， the hydrogen concentration in the pressurized cabin increases in size， but no alarm limit is reached. System is working properly. 4.3 singl
32、e-cell test Test battery is sealed lead-acid battery ， put it in the test box. A wire even it out and connected to the battery tester， opening sensor in the box and installing Small fans to mix gas at the bottom of box. 4.3.1 constant voltage charging During constant voltage charging， sealed lead ac
33、id batteries hydrogen evolution curve as shown in Fig.7. From the diagram， constant voltage charging sealed lead acid battery system， the hydrogen concentration is always maintained at a 0% level， almost no hydrogen emission. 4.3.2 Constant current charging Sealed lead acid battery for constant curr
34、ent charging hydrogen curve in Fig.8. At the end of constant current charging， hydrogen concentrations increased sharply in the box. When it reaches a specified concentration of hydrogen gas alarms （50%LEL， hydrogen volume ratio point 2%） ， the main interface software is running warning light from g
35、reen to red alert. During 04% 10concentrations of hydrogen within the system are able to engage in normal testing. In summary， “based on LABVIEW real-time measurement of hydrogen concentration measuring system for electric vehicles“ to reflect the real concentrations of hydrogen within the specified
36、 space in real time，the hydrogen concentration alarm when the alarm limit is reached， system stability， sampling for high-speed and accurate， it meets the design requirements. 5. Conclusions In this study，based on virtual instrument LABVIEW platform and C/C+ language system software have developed a
37、 hydrogen concentration detection device for electric vehicle ，which low cost， reliable performance， convenient.Also，it can ensure system reliability， real-time performance and stability. In addition to collecting relevant data， it can also perform the following functions： （1） Multi-channel data acquisition， according to the specific needs， it detects multiple parts of the hydrogen concentration； （2） In certain cases， finding its own hydrogen concentration alarm limit values； （3） Concentrations of either channel exceeds a
