Reliability Test System Design Of NMR Logging While Drilling Control Circuit

Nuclear magnetic resonance(NMR)logging while drilling tool works in harsh environment for a long time during downhole operation.This requires high reliability of the tool.The control circuit is an important part of the NMR tool.In order to improve its reliability and accelerate the progress of the tool research and production,an automatic test system for reliability test of control circuit is designed in this thesis.The effect of HALT&HASS reliability test aiming at improving circuit reliability is analyzed.According to the functional characteristics and practical application background of the NMR logging control circuit,the test contents and indexes of the circuit are determined.Then the overall framework of the system is designed.The system hardware consists of the central control module,DC programmed power module,signal simulation and parameter measurement module and system module.Through subdividing each module into an industrial computer,data acquisition card,oscilloscope and other specific hardware devices,the overall hardware system architecture based on LAN,RS-232,USB and other hybrid bus design is determined,and the hardware system design is completed by modules.The system software is designed in Lab VIEW,which works as the development platform,and uses a database to manage data.According to its different functions,the software design is seperated into 7 parts,such as test interface,scheme setting and data query,and the system interface is designed on this basis.The program framework is divided into three layers: the user layer,the application layer,and the driver layer.Through the hierarchical programming and then according to the design process orderly combination to complete the system functions of each module.The software system combines multithreading,VISA,dynamic call,SQL,Active X and other techniques,and finally realized instrument control,test execution,data management,data analysis and other functions.The function test of the control circuit is carried out by simulating the field test process under normal temperature condition.The results show that under the test environment of the existing hardware equipment of the same type,each part can work according to the predetermined test process and steps.The functions of the software system run normally,which prove that the system can realize the reliability automation test of the control circuit.