Study On Measuring Coil Of Long Duration Pulse Current With Nanosecond Unipolarity

As a natural strong electromagnetic pulse,lightning electromagnetic pulse has a great threat to the safe operation in the fields of aerospace,electronic communication and power transmission.Whether the protection device for preventing lightning electromagnetic pulse interference can operate correctly depends on the accurate measurement of lightning current.Therefore,how to achieve accurate measurement of lightning current has important research significance.Based on the spectrum analysis of unipolar long duration pulse current,the basic theory and frequency characteristics of self-integrating Rogowski coils are studied.In view of the characteristics of unipolar pulse current frequency span,how to widen the Rogowski coil frequency range is studied.According to the transfer function of Rogowski coil,the amplitude-frequency characteristics of Rogowski coils with different materials and different electromagnetic parameters and the different integral resistances are simulated.On this basis,the experimental study of the measurement characteristics of Rogowski coils is carried out,and the influence of different parameters on the measurement results of Rogowski coils is obtained.Based on the spectrum analysis of the H component of the lightning current,the Rogowski coil is optimized to meet the band requirements and current amplitude requirements of the nanosecond pulse current measurement,and the nanosecond square wave current source is used for the Rogowski coil.The response time is calibrated.A lightning current H component experimental platform was built,and the measurement characteristics of the Rogowski coil were experimentally verified,and the measurement results were compared with a standard coaxial tubular shunt.The results show that for the magnetic core of the same material,as the magnetic permeability of the core increases,the working band of the Rogowski coil is shifted to the low frequency direction as a whole.Therefore,the manganese-zinc ferrite with higher magnetic permeability is suitable for the measurement of signals with more low-frequency components,while the nickel-zinc ferrite with lower magnetic permeability is suitable for the measurement of signals with more high-frequency components;The small integral resistance can widen the operating band of the coil;increasing the cross-sectional area of ??the core under practical conditions can reduce the lower limit cutoff frequency of the coil.The Rogowski coil for measuring the H component of the lightning current has a response time of no more than 1 ns,a normal measurement frequency range of 102 to 107,and a sensitivity of 101.2 A/V.When the current amplitude is not more than 4k A,the measured value of the measured H component of the lightning current is less than 2% of the peak,wavefront time and tail time compared with the standard coaxial shunt,under each current level.The standard deviation is no more than 1%.