Research On Relationship Of Power Line Filter's Performance And Factors Such As Temperature And Techniques Of Anti-saturation

Power line filter is widely applicated in field of medicine,communication military and so on.lt is confronted with extreme temperature environement which is wide-ranged and bears high operating current.Extreme environmental temperature can change the performance of the filter and excessive current can lead to the saturation of the filter.The influence rule of temperature and biased current's influennce on power line filter is investigated through experiments.A measure to improve the filter's ability of anti-saturation is proposed.Rationale of the filter is introduced and then a power line filter is designed for the use of research.The corresponding relation of paralmeters in filter is analyzed in theory,including the relation of magnetic core's permeability and common-mode choke's inductance,the relation of capacitance,inductance and S parameter of the filter.Based on influence rule of temperature and bias current's influence on capacitance and inductance,influence rule of temperature and bias current's influence on filter's S parameter is deduced.With capacitors and ferrite cores in different material,platforms are set up to test the impedance of the components and S parameters.The impedance test is completed by analytic network process.Coaxial cable is placed between DUT and testing instrucment to improve the accuracy of the test in the testing platform.Results show that under the influence of the temperature,capacitance and inductance have combined effect on S11 and S21 of the filter.The amplitude of S11 and S21 is determined by amplitude of inductance,resonant frequency of S21 is determined by the amplitude of capacitance.Resonant frequency of S11 is determined both by the amplitude of capacitance and inductance.Adjust the number of winding choke so that the common-mode can saturate under the testing range in biased current testing.The safety of power source and testing instrument is guaranteed by use of a buffer network and isolation capacitors.Analyze the magnetization process of the ferrite core of the common-mode choke.Evaluate the degree of filter's saturation by ?S11.Lower ?S11 equates to closer to saturation.Results show that higher the biased is,lower the inductance of common-mode choke is.The speed of decline decreases during the change.While the filter is close to saturation,the S parameter do not decrease to zero suddenly,the speed of decline decreases in the process.Based on the principle of filter's saturation,a kind of wind applicated in common-mode choke is proposed.The wires are winded on the ferrite core in pairs and equal interval.The method postpones the filter's saturation by eliminating differential-mode flux.test The filter's S parameter under the change of bias current with the porposed winding method,feasibility of the method is verified in application of anti-saturation.