Design Of Calibrator For Large Current Testing Equipment

In this paper,we first analyze the existing problems of high current tester calibration device,and adopt a new idea and principle to design a calibration device specially designed for high current tester.Firstly,the feasibility of the design scheme is evaluated,and then the function of the hardware platform and the flow of the software program are designed.At the same time,the magnetic field simulation and measurement data processing algorithm of the calibration coil are studied theoretically.Through the theoretical calculation and experimental test,the final determination of the core components of the calibration coil program selection.Control part of the sampling ARM platform to achieve the serial port,network port,USB,logic and timing control program Linux kernel program transplant,and HMI man-machine interface screen design,not only to test the system platform of high precision,To achieve a multi-functional,user-friendly operation.Hardware system design is divided into six parts,the system power supply design,module isolation and protection circuit,square wave generator and logic level conversion,output detection circuit design,calibration coil design,ARM core circuit design.System power supply design According to the input power supply indicators,as well as the different voltage and power requirements of the module,a detailed component selection and circuit design,module isolation and protection circuit design to ensure the safety of the equipment and electrical isolation of the module,And at the hardware level to prevent the core components of the calibration coil for a long time due to damage caused by power.Square wave generator and logic level conversion circuit designed 1kHz square wave signal,for the test of the high current tester input IF excitation calibration signal.Logic level conversion to 3.3v,5v and other different electrical characteristics of the I / O port,the chip provides a match between.The output detection circuit is designed so that the output calibration signal is converted to a true RMS value,so that the ADC can accurately sample the output signal to ensure that the output signal can be accurately sampled,whether it is 50 Hz power frequency,100 Hz bread wave,1k Hz square wave can be accurately sampled.The design of the calibration coil details the theoretical research of the core components and a large number of experimental tests,and finally determine the parameters to meet the performance requirements and accuracy of the calibration coil,so that the ampere-turns more than 25 k,the maximum can be calibrated 25 kA Frequency AC and DC current,and do pure impedance,capacitive reactance and inductance meet the requirements of the index,and as much as possible to reduce the magnetic interference between multiple coils,measurement accuracy of 2% of the sampling error and 5% of the system error.ARM core circuit design for the operation of the Linux operating system provides a hardware platform,so that the Linux kernel and communication,control,data processing algorithm driver can run correctly.Finally,in order to verify the calibration performance of the system,the control,communication and data processing algorithms of the ARM platform are debugged and verified respectively.The correctness and stability of the program are debugged,and the interface program and script program of the industrial control screen are debugged.Platform control system composed of the two perfect match,while ensuring the entire system to the correct and stable operation.