Design Of Automatic Measurement System For Amorphous Wire Impedance

Amorphous wire is a kind of amorphous alloy microfilament with special giant-magneto impedance effect.It is a research hotspot in the field of high performance magnetic sensors and magnetic recording.In fact,the impedance of amorphous wire is a tensor form.In a certain interval,the off-diagonal component has greater sensitivity,and linearity.So it’s widely used in linear sensors.At present,there are some problems such as low automation,high cost and f ussy data processing for the system of amorphous wire impedance measurement.In order to study the characteristics of amorphous wire impedance effect,this paper designs and realizes an automatic measurement system of amorphous wire impedance based on common instruments.In this paper,the expression of impedance tensor of amorphous wire is deduced and the impedance tensor model under high frequency is established.According to the theoretical relationship,the method of measuring S 21 parameters is proposed to realize the impedance measurement of amorphous wires.The hardware design includes the amorphous wire diagonal and off-diagonal impedance measuring circuit.Main control circuit is based on AD8302 circuit.Furthermore,there is a turntable structure f or nonlinear magnetic field.The software includes the transmission sampling data based SCM program,as well as the overall system of the overall management of the MFC based system control software.Finally,the whole impedance automatic measurement system is built.The impedance curves under different conditions are obtained by the measurement system.The results are consistent with theoretical analysis.The giant magneto impedance of the amorphous wire is related to the excitation DC bias,frequency,amplitude and the angle of the external magnetic field.The effectiveness of the whole system is verified.