| As the electric power system develops to extra-high tension and large capacity, thedemand for the current sensor becomes increasingly higher. Nowadays the electricpower system uses the electromagnetic current sensor and the optical current sensor.Because of the the disadvantages and limitations of this two current sensors, this thesistook advantage of a new-type function material, Giant Magnetostrictive material (GMMfor short) and designed a new current sensor. This current sensor has the advantages ofno magnetic saturation, high precision, high speed, and not affected by environmenttemperature. It not only sense the operation state of the power lines, but also proceed theprotection quickly when the power lines goes wrong.This thesis presented the design idea of the new-type current sensor based onGMM, and firstly studied the basic characteristics of GMM through experiment. thendesigned the structure of the new-type current sensor, and divided it to three units on thebasis of function: sensing unit, amplification unit, and trigger unit. We designed thestructure and parameters of each unit in detail, studied the interference between phaseswhen monitoring the power lines, and presented a reasonable monitor location.Furthermore, the key technologies of sensing unit were studied. estimated theGMM force to analyze the load capacity of sensing unit, and confirmed the rationalityof the device. Then, this thesis went into the loss of the device, which mainly comesfrom the magnetic hysteresis and eddy current phenomenon. Used Jiles-Atherton modelto modeling the magnetization intensity of GMM, identified the model parameters byexperiment and BP neural network, acquired the hysteresis loop conform to theexperimental loop by numerical modeling, and calculated the magnetic hysteresis loss;also modeling the eddy current loss by Maxwell equations, and results showed that theeddy current loss is low when the skin depth is shallow or the eddy current cutofffrequency is low. |
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