Dual-current-injection CSCC Active Common-mode EMI Filters with High Insertion Loss for DC-DC Converters

With the increase in the switching frequency and power density,DC-DC converters encounter more severe electromagnetic interference(EMI)problems.To suppress the common-mode EMI generated by converters,as well as maintain the high-power-density of converters,the active EMI filter(AEF)has attracted increasing interest owing to its small volume.The EMI suppression effect of the common single-stage single-sense single-injection AEF is confined because of the limited insertion loss,and the volume of the multi-stage AEF will be bulky.To solve this problem,this paper proposes a compact dual-current-injection current-sense current-compensation(DCJ-CSCC)AEF to increase the insertion loss in the entire conducted EMI frequency band,as well as considering the volume of the AEF.The structure and operating principle of the proposed AEF are introduced.Finally,taking a boost converter as an example,the effectiveness and advantages of the proposed DCJ-CSCC AEF were verified through a simulation and experiment,the results show that the proposed AEF has a better EMI suppression effect on the entire conducted EMI frequency band with a similar volume compared with existing single-injection feedforward current-sense current-compensation(FF-CSCC)and feedback current-sense current-compensation(FB-CSCC)AEFs.This paper provides a new selection for EMI suppression in DC-DC converters.

Filter Design of Wireless Base Station Power Supply

The design of electromagnetic interference(EMI)filters needs to fulfill the EMI standards.Designing a filter is a time-consuming process for new engineers as well as for those experienced engineers.This paper measures and compares the noise spectrum of the wireless base station power prototype with and without the original filter.The ideal insertion loss(IL)of the original filter is obtained by combining calculation and simulation.It is pointed out that the effect of the original filter is not good.Based on the improved insertion-loss method,the source impedance model of the prototype is established by combining measurement and theory.A procedure for designing EMI filters for switch power supply will be presented.The filter design procedure makes it possible to design filters quickly and easily.Finally,the proposed filter design method is proved to be effective by the EMI measurement of the wireless base station power supply prototype.

Study of the Characteristics and Suppression of EMI of Inverter with SiC and Si Devices

The paper systematically studies the impacts of two major factors:device switching actions and inverter switching frequency on the whole EMI spectrum.Several powerful experimental results of electromagnetic interference(EMI)in voltage source inverter(VSI)with SiC and Si devices are provided.As far as the influence of switching actions is concerned:faster switching speed will generate higher EMI noise levels in the high frequency range,and ringing in the device switching will also make the EMI noise near the ringing frequency range worse.In the meantime,increasing of the switching frequency of the inverter will result in a higher EMI noise peak for the whole EMI spectrum.In order to suppress the EMI noise of the converter to meet standards,Random PWM(RPWM)and EMI filters are adopted.With RPWM,the EMI current can drop a few more dB than that with SVPWM,which makes the filter work better.Also,as extra attenuation can be provided,it provides the benefit of reducing the weight and volume of the inductor of the filter.Therefore,the combination of an advanced modulation strategy and EMI filter is proposed for suppressing of EMI noise in an inverter.

Hybrid Common-mode EMI Filter Design for Electric Vehicle Traction Inverters

A feedforward current-sense current-compensation(CSCC)active EMI filter(AEF)for the direct current-side common-mode(CM)electromagnetic interference(EMI)suppression of high-power electric vehicle traction inverters is analyzed and designed.A detailed design of the components with formulas is provided based on an analysis of the CSCC AEF,including the CSCC AEF topology and its implementation.The feedforward active filter stage was implemented using a simple current transformer and a small circuit board.Only a small passive filter with a high resonant frequency is required for high-frequency noise attenuation.The filter’s effectiveness was validated using the simulation results and experimental measurements.

Planar Magnetic Integrated Harmonic Filter with Reduced EMI Noise

Through the analysis of the circuit structure and electromagnetic interference(EMI)conduction path,the structure of the traditional harmonic filter is optimized so that it has the ability to suppress EMI.Using the structure of planar magnetic integration not only ensures the basic harmonic suppression ability of the harmonic filter,but also improves the EMI suppression effect.With a single-phase voltage source 500-W SiC inverter as the platform,the feasibility and effectiveness of the design scheme are experimentally verified.The results indicated that the planar magnetic integrated harmonic EMI filter satisfies the design requirements.Additionally,the proposed planar magnetic integration scheme can significantly reduce the volume and weight of the filter and increase the power density of the entire system.

Research and Modeling on the Characteristic Changes of EMI Filter Passive Components under the Influence of Aging

At present,the power density of power electronic devices in data centers and electric vehicles is constantly increasing,and numerous electronic components are concentrated in a tight,high-temperature environment,which aggravates the performance degradation of electronic components.Consequently,X and Y capacitors,common-mode inductors,and differential-mode inductors used for electromagnetic interference(EMI)suppression suffer from aging effects,and their performance continues to decline.However,the electromagnetic compatibility test is often conducted immediately after the power electronic equipment leaves the factory.The electromagnetic compatibility of power electronic equipment is affected by aging,which is not assessed in current industrial testing.This study conducts aging experiments on passive electronic components in EMI filters and measures the impedance in the frequency range from 150 kHz to 30 MHz.Subsequently,a multi-element aging model based on electromagnetic field analysis is established.The proposed model is suitable for electromagnetic compatibility analysis considering aging.Finally,the aging performance of a commercial two-stage EMI filter is predicted to verify the model proposed in the study.The proposed model explains the degeneration of the EMI filter with aging in the frequency range of 150 kHz to 1 MHz,with a maximum amplitude error of 0.58 dB and phase error of 1.0°.