| PWM(Pulse Width Modulation)drive system has the advantages of high efficiency,low system loss and fast dynamic response.It is widely used in military and civil equipment fields,including vehicle borne radar turntable,vehicle borne gun turntable,aerospace vehicle,industrial robot,new energy vehicle and other industries.However,there are high-frequency switching devices in PWM drive system,which will produce harmonic current and conducted interference at the moment of turn-on and turn off,causing serious EMC(Electromagnetic Compatibility)problems in the system.In order to make the vehicle equipment work normally in the complex electromagnetic environment,it is necessary to study the electromagnetic compatibility of the vehicle turntable drive system.This paper analyzes and studies the EMI(Electromagnetic Interference)modeling method of PWM drive system:1.Combined with the three elements of electromagnetic interference,the interference source,transmission path and coupling mechanism of vehicle turntable drive system are discussed.The electromagnetic interference generation mechanism of IGBT(Insulated Gate Bipolar Transistor)is studied,and the parasitic parameters of passive devices in high frequency state are analyzed.2.According to the structure characteristics of PWM Variable frequency speed regulation system,the generation mechanism of EMI conducted interference in vehicle turntable drive system is analyzed.The time and frequency domain characteristics of PWM power converter output waveform are discussed.The formation mechanism and propagation path of EMI differential mode interference and common mode interference are studied.The electromagnetic interference model of vehicle turntable drive system is established.3.The generation mechanism of high frequency harmonics in three-phase rectifier and AC/DC converter is analyzed.The EMI interference model is established.Combined with relevant standards,the experimental method of EMI conducted interference is studied.The electromagnetic compatibility experiment is carried out for the drive system of vehicle turntable.The simulation waveform and experimental results of EMI conducted interference are compared and analyzed.4.Based on the working principle of EMI filter,the equivalent circuit model of EMI filter is established.According to the frequency domain characteristics of EMI conducted interference in power electronic devices,the design method of differential mode enhanced filter is studied.Finally,the EMC rectification analysis and experimental verification are carried out for the conducted interference problems in the EMI experiment of the vehicle turntable drive system. |
