Research On High Precision Passive Resistance Generators

Resistance generator was widely used in automotive and aeronautical instrumentation calibration,multimeter impedance test,electronic circuit debugging andother occasions,as an important benchmark source.The present resistance generation technology mainly includes active and passive technology.According to the disadvantage of the great power consumption and electromagnetic interference to external circuits that the active resistance generation technology had,the passive resistance generation technology withthe simple design principle and easy implementationwaswidely used in the low power instrumentation calibrationapplications.But the passive resistor generator’stechnical specifications,such as the accuracy and stability,was still inadequate.Therefore,the research on high-precision passive resistance generator was an important problem that needed to be solved urgently.Aimed at the issuesmentioned above,the research on high-precision passive resistance generatorwas presented.ARM was used to control the relays switching to output passive resistance,as the system main control unit,and the calibration function was achieved by communicating with thehigh-precisionmultimeter,meanwhile,the software interfacedisplay and user operations identificationwas realized usingthe LCD and the touch conversion chip.The quantitative relationship between the resistor combination and its output resistance value was determined,and the resistance output simulation equation was established,by analyzing the hardware factors affecting the precision of this passive resistance generator,using the method of simulating actual output within the various hardware factors.The optimal resistor combination whose output value was closest to the set resistance value was obtained,by solving the simulation equation,using the breadth-first search algorithm and the branchand bound algorithm.The breadth-first search algorithm wasselected as the optimal resistor combination algorithm,after comparing the time complexity of the two algorithms.The hypogynous machine software was developed based on GUIgraphical interface library,using the human-computer interaction unitto recognize and respond to the user operation,realized control of the resistance generator by the hypogynous machine software;Based on the Visual Studio 2010 development environment,the C# language was used to design the epigynous machine software,completed the information exchange between epigynous machine software and resistance generator by USB HID communication protocol,to achieve passive resistance output,system calibration,information monitoring functions,thus meeted the user’s demand of controlling the resistance generator both by hypogynous machine or epigynous machine,achieveda good human-computer interaction performance.Experimental results showed that,in a qualification of 1.0 ? ~20.0 k ? output range with a resolution of 0.1 ?(within 1 k ?,and the resolution is 1 ? in the larger output range),in the output range of 1.0?~11.0?,the maximum relative error of the output of the system is 2.4%;in 11.1?~12 k ?,the maximum relative error was 0.8%,in 12 k? ~20 k?,the maximum relative error of the system output is 0.029%,the system response time is less than 500 ms.The system hada good output reproducibility,and could reduce the components aging influences on the output accuracy of the systemeffectively,which hadsome certain stability.Therefore,the passive resistor generator solved the problem of the low output accuracy and poor stability that the current passive resistance generation technology had,provided a new method for high-precision passive resistance output,which had a high engineering application value.