Research Of Pulse Characteristics Measuring Technology Of Magnetic Materials Used By Power Line Filter

In the electromagnetic environment of power and electronic system,there is not only high frequency harmonic interference but transient pulse interference.The effect of power line filter in the electromagnetic compatibility design is to control both harmonic interference of 150kHz-30MHz and transient pulse interference.The inductor of power line filter is actually made with ferrite core coil.The pulse characteristics of magnetic cores play a important role in the pulse suppression performance of power line filter.The pulse characteristics of soft ferrite materials commonly used in power line filter are investigated by experiment,along with their influence on the pulse suppression performance of power line filter.The Insertion Loss of power line filter is calculated by current source model.The inhibition of transient pulse current by inductor is analyzed through PSpice simulation.The suppression theory of common-mode interference and the differential-mode interference by power line filter is analyzed and corresponding equivalent filter circuits are established through PSpice simulation.The influence of inductance and capacitance to the pulse suppression performance of filter is analyzed under the excitation of transient rectangular pulse current and double exponential pulse current.Soft ferrite materials will be magnetized and demagnetized quickly under the excitation of transient single pulse and the inductance of coil is a dynamic inductance L(t)under pulse magnetization.The inhibition of transient pulse current by inductance of coil is measured by average pulse permeability ?p of core materials.The magnetization process of different toroidal ferrite cores under the excitation of transient rectangular pulse and double exponential pulse is researched by experiment.The voltage and current of coils are measured and the dynamic inductance and average pulse permeability of core materials are calculated through noise reduction process and numerical calculation.The difference of the pulse characteristics of different ferrite cores are analyzed.Different filters made of different ferrite materials are designed and the measuring circuit of power line filter under the excitation of common-mode transient pulse is established.The voltages of load before and after inserting the filter are measured.The Insertion Loss based on time-domain pulse energy and frequency-domain pulse voltage are put forward to evaluate the pulse suppression performance of power line filter.The influence of pulse characteristics of core materials to the pulse suppression performance of power line filter is concluded.