Research On Electromagnetic Interference Modeling Of Four Quadrant Converter And Active Suppression Method

The four quadrant converter is an important electromagnetic interference source for the train.It is of great significance to model the electromagnetic interference of the traction converter to provide guidance for its electromagnetic compatibility design.At present,the passive suppression methods such as shielding and filtering will increase the volume,weight and cost of the system.If the electromagnetic interference can be actively suppressed from the source of electromagnetic interference,the negative impact of the passive suppression means can be alleviated.Based on the above situation,this thesis studies the electromagnetic interference modeling and active suppression methods of four quadrant converter.Firstly,this thesis models and analyzes the electromagnetic interference source and the interference coupling path of the four quadrant converter.Then,the correctness of the electromagnetic interference model established in this thesis is verified by comparing the electromagnetic interference spectrum measured on the experimental platform of the low-power four quadrant converter and the spectrum based on the electromagnetic interference model simulation.Then,this thesis proposes a ferrite choke model and its parameter determination method for the current lack of ferrite choke model in electromagnetic compatibility simulation.An actual ferrite choke is modeled by the proposed model and parameter determination method,and the ferrite choke model is applied to the electromagnetic interference simulation of the four quadrant converter.The fitting results of the model to the actual ferrite choke impedance and the simulation results in the four quadrant converter prove the correctness of the model and the parameter determination method.Then,for the low-band electromagnetic interference of the four quadrant converter,the spread-spectrum PWM technology is applied.The two kinds of spread-spectrum PWM techniques,such as periodic spread spectrum PWM and chaotic spread spectrum PWM?are applied to the four quadrant converter.In the simulation,the effects of two kinds of spread spectrum PWM techniques on electromagnetic interference are studied,The suppression effects of different spread spectrum techniques and different spread width are compared,and the influence on the output voltage of the four quadrant converter is analyzed.In addition,with the increasing research and application of SiC MOSFETs in traction systems,based on the high-frequency electromagnetic interference caused by the voltage and current spikes and oscillations of the switching process during the application of SiC MOSFET,an active driving circuit is designed based on the analysis of the switching process and the voltage and current spikes and oscillation mechanism.In the experiment,the suppression effect of the proposed active gate driver on the spike and oscillation of the voltage and current of the SiC MOSFET and the suppression of the high frequency electromagnetic interference are verified.