Research On Wide Range Current Measurement Based On Rogowski Coil

Compared with traditional electromagnetic current sensor,Rogowski coil has been widely used in current measurement due to its non magnetic saturation phenomenon,simple structure,and ability to measure megaampere level current.From microelectronic devices to high-power systems in industrial facilities,the environments for measuring current in various fields is becoming increasingly complex,and the amplitude range and frequency bandwidth of the measured current are becoming wider and wider.However,Rogowski coils are generally used for measuring fixed range currents,which can cause large current noise over large ranges;Small measurement ranges are not conducive to measuring large currents such as pulsed currents.Therefore,this thesis designs a flexible Rogowski coil current measurement system for wide range and broadband current measurement.In this thesis,the principle of measuring current with Rogowski coil is analyzed,and a parameter model of flexible double layer coil is established.The common errors that affect the performance of the Rogowski coil are analyzed and simulated,providing a theoretical basis for subsequent circuit simulation and design work.Through simulation and analysis of the relationship between the structural parameters,electromagnetic parameters,and sensing performance of the coil,a reasonable parameter design for the coil was carried out.In order to enable the coil to measure a wide range of current,using a small cross-sectional diameter,a composite integration circuit with a switchable range was designed,which has the ability to measure large current signals.To improve the measurement accuracy of small signals,the coil adopts a double layer winding method,which increases the mutual inductance coefficient of the coil and enhances the induced signal.At the same time,it can effectively weaken magnetic field interference and improve the anti-interference performance of the coil.The final design coil has a sensitivity of 0.1 m V/A when measuring power frequency current,and a measurement range of 3 A to 10 k A.In order to broaden the bandwidth of the coil for measuring current,it is possible to appropriately change the structural parameters of the coil to increase the upper limit frequency,and increase the integral constant to reduce the lower limit frequency.The final bandwidth upper limit is 20 k Hz.Silicone rubber material is selected as the coil skeleton,and enameled wire is used as the winding material to meet the low cost requirements of sensors.A Rogowski coil current testing system based on FPGA is proposed,and the system hardware and software are designed.The digital processing of coil induction signals is realized,and functional simulation is performed.The average sensitivity of the coil measured through experiments is 40.72 m V/A,and the coil linearity is good.The average sensitivity error is 0.83%,and the maximum measurement error does not exceed 2.3%.Conduct a temperature stability experiment on the current measurement system,and the maximum measurement error of the measured voltage signal obtained in the experiment shall not exceed 0.85%.According to experimental tests,the correctness and practicality of the design of the Rogowski coil are verified,which has guiding significance for the design of a flexible Rogowski coil for wide range current measurement.