Research Of Technology On High Current Transducer Based On Magnetic Sensor Array

As a major international cooperation project, the International Thermonuclear Experimental Reactor (ITER) aims at solving the future energy crisis; the poloidal field converter system is not only an important part of the fusion reactor but also the largest power converter system in the world so far. Its rated capacity reaches 4600 MVA and rated output current from each power supply unit reaches 55 kA, which triggers the urgent demand for large current measurement.In order to meet the current measurement of ITER in a highly stable,high-precision, and quick response way, a new type of current sensor based on magnetic sensor arrays has been developed. The main results and innovation of this work are as follows:The magnetic field and its gradient distribution around the poloidal field current-carrying busbars has been analyzed based on electromagnetic field model of current infinitesimal. Based on the analysis results, the advantages and disadvantages of adopting the circular arrangement structure and the rectangular arrangement of the magnetic sensor array are compared. The crosstalk suppression method for the circular magnetic sensor arrays has been proposed in the framework of double parallel straight wires model.The technical scheme for the structure design of the magnetic sensor arrays'circuit has also been proposed; the key technical problems in the engineering realization of the magnetic sensor arrays have been analyzed in detail and the necessity of the sensitivity normalization of multi-sensor on arrays has been expounded. We have focused on the selection of the magnetic sensor, the buffer circuits, the temperature compensation circuits and the grounding design to ensure the accuracy of the magnetic sensor arrays' measurement and the reliability of the operation.In order to solve the problem that the circular array magnetic sensor arrays are no longer suitable for the measurement of the large-dimension cross-sectional current carrier busbars, the technical scheme of adopting the rectangularly arranged magnetic sensor arrays is proposed for the first time. In our proposed scheme,discontinuity point segment measurement in the integration of the loop magnetic field and the high-order Simpson numerical integration algorithm in the data processing have been used to greatly minimize the calculation error caused by the drastic changes of magnetic field gradient of the rectangular integration loop and to extract the engineering steps for the rapid design of the rectangular arrangement magnetic sensor arrays.To meet the electromagnetic compatibility requirements of magnetic sensor array in complex conditions such as the field of nuclear fusion, the noise problem introduced by the propagation of drastic du / dt through the electric field coupling during the converter operation has been studied; the noise transmission channels under both the common mode and differential mode has been discussed, and the inverse parallel structure which is superior to the conventional sensor signal transmission mode under the premise that the signal quality cannot be improved by using the filter circuit has been proposed. The experimental results show that the coupled noise in the measurement signal is well suppressed by using our proposed method.We have completed product development and testing. The experimental data shows that it can meet the requirement of the current measurement on large-dimension cross-sectional busbar, has high reliability and achieves the accuracy class of 0.5 or more, and have a better crosstalk suppression capability and electromagnetic compatibility. The sensor not only meet requirements of the ITER current measurement, but also can be used in the national defense industry, scientific research, metallurgy and other industries involving high current detection.