Development Of Handheld High Precision Multifunctional High Resistance Meter

In recent decades,our country has been developing rapidly in the field of new materials,and the level of science and technology has been greatly improved.The resistance parameters of new materials have important significance for electrostatic protection.High Resistance Meter is a special instrument for anti-static products of the resistance parameters and insulation resistance test of insulation materials and electrical equipment.Although there are many types of High Resistance Meters on the market,most of them are poor performance,narrow range,and can not meet the requirements of static protection test and insulation resistance test.Therefore,this paper develops a portable multi-function wide-range Digital High Resistance Meter,the research work of this paper is as follows:1)In this paper,the equivalent model of high value resistance is analyzed and compared,and the advantages and disadvantages of the existing resistance measurement principle and method are compared.The resistance measurement method combined with the inverting circuit and the integral circuit is used to design the resistance measurement system in this paper based on the measurement accuracy,the measurement range and the volume of measurement system.In order to suppress the error current caused by the interference noise and improve the speed of the measurement,this paper establishes the time-varying model of the error current and presents a measurement algorithm of alternating polarity of the excitation voltage.this paper presents a method of alternating transform excitation voltage polarity.2)Taking into account the function and power consumption,this paper designs a low-power and high-performance hardware system,which is divided into three functional modules that are the analog front-end,the human-computer interaction and the data storage.In order to expand the field application and improve the flexibility of the Digital High Resistance Meter,this paper integrates the digital multimeter module.This paper has completed the design of the current to voltage circuit,the precision microcurrent source circuit,the A/D conversion circuit,the D/A conversion circuit,the high voltage generating circuit,the digital multimeter module,the human-computer interaction,the data storage circuit and the power system.3)In this paper,the control software is written based on the Real Time Operating System of the ?C/OS ? for achieving display the value of the measured resistance and current,data storage,off-line analysis,ambient temperature and humidity measurement,digital multimeter,the SD card reader of USB,human-computer interaction and so on.With measurement of voltage,current,resistance,the on-off test and the diode test,the measurement relative error of digital multimeter module is less than 1.5%.The relative error of Digital High Resistance Meter is less than ± 3% in the range of 105?~109?,ang the relative error is less than ± 10% in the range of 1010?~1013?.