Research On EMI Of Motor Control System Based On Silicon Carbide (SiC) Devices

Novel power electronic devices represented by Silicon Carbide(SiC)devices bring new opportunities to improve the efficiency and power density of motor drive system,and also provide new breakthroughs and possibilities for special applications such as aerospace and ship propulsion.However,as new devices used in complex motor drive system,there are still many challenges to make full use of their advantages.The switching characteristics of silicon carbide devices are different from silicon(Si)devices.For motor control system,the characteristics of electromagnetic interference(EMI)sources will be changed.In addition,the application of silicon carbide devices is beneficial to the increasement of switching frequency of motor control system,but the problem of EMI will become more prominent with high switching frequency.The paper aims at the problem of EMI in motor control system,and some work has been done.Firstly,a set of motor controller based on SiC devices and a set of motor controller based on Si devices for comparison are developed with modular design method.The design requirements and precautions of gate drive of fast switching devices SiC are introduced,which provides the basis of hardware for this research.Through theoretical analysis,this paper reveals the sources and the conduction path of EMI current in motor control system.Through mathematical modeling and calculation,the main factors affecting the EMI spectrum and the specific influential mechanism of these factors are explained.This paper also introduces the method of designing an EMI filter.When analyzing the characteristics of EMI filter,it is found that the parasitic parameters not only resonate with inductor and capacitor,but also add more mutual inductive couplings to the EMI filter,which will affect the attenuation of the filter.Reducing mutual inductive couplings is beneficial to the improvement of filter performance.The paper adopts two methods to drop EMI current of motor control system below the standard: advanced modulation strategy and EMI filter.Considering the filtering performance as well as the weight and volume of the system,this paper combines the two methods and experimental results show it is feasible.