Research On Conducted Interference Suppression Of Accelerator Power Supply

Heavy ion accelerator is an important device used to study the frontiers of nuclear physics,such as nuclear structure,nuclear astrophysics,new physics beyond the standard model and the properties of strongly interacting matters.In recent years,global scientific and technological powers such as the USA,Germany and Russia have successively built a new generation of high current heavy ion accelerators.To develop the cutting-edge technology of heavy ion accelerator scientific research in China,a new generation of high-current heavy ion accelerator device(HIAF)was built by the Institute of Modern Physics,Chinese Academy of Sciences in the national ’ 12 th FiveYear ’ scientific project plan.The power supply and magnet system are an important part of the accelerator magnetic field.To obtain high current,high quality beam and high energy,the accelerator device highlights strict requirements for rapid pulse response and stable output of the accelerator power system.As the main power converter,semiconductor switching devices and circuit topologies must have good electromagnetic compatibility to meet the power supply’s stable output current requirements.However,with the development of technology,the switching frequency of semiconductor switching devices and the complexity of circuits are increasing rapidly,which makes the electromagnetic interference(EMI)problem inside the accelerator power supply increasingly serious,and seriously restricts the breakthrough of accelerator power supply technology.The electromagnetic compatibility of the power supply influences the reliable and stable operation of the power supply,followed by the quality of the accelerator beam.Therefore,the problem of electromagnetic interference in the energy supply must be resolved as a matter of urgency.Based on the noise suppression mechanism of the power supply and the three elements of electromagnetic interference,the investigation of the interference source,the analysis of the transmission path and the filter design are launched.The electromagnetic interference source of the accelerator power supply will not only cause the oscillation of the circuit to cause the digital circuit to malfunction,but also may affect the electromagnetic radiation of other electronic devices in the circuit.Therefore,research on the interference source can not only eliminate interference from the source,but also reduce noise early in the power supply design.The study of the transmission path may be extended to the extraction of the impedance curve of the power circuit and to the modelling of the equivalent high frequency circuit.It can provide a sound theoretical basis for analyzing the electromagnetic compatibility of the accelerator power supply.At the same time,in the early stage of the power supply design,the electromagnetic interference problem can be avoided from the perspective of parasitic parameters,so as to shorten the power supply development cycle and reduce the power supply development cost.The EMI filter design is an interference suppression method to rectify electromagnetic noise when the power supply has been designed.The main innovations and search results in this article are:(1)Firstly,based on the electromagnetic interference theory,this paper analyzes the electromagnetic interference noise source,and models the high frequency characteristics of the semiconductor switching device,which intuitively reflects the high frequency characteristics of the device in the working state,which provides a reliable basis for the selection of the accelerator power semiconductor device and the subsequent EMI analysis.On this basis,the feasibility of the high frequency modeling method is verified by the calculation method of the potential circuit,the switching spike is reproduced,and the parameter selection of the switching spike suppression absorption circuit device is completed.Compared with calculating the influence of parasitic parameters on device function from the perspective of semiconductor physics,the circuit interference problem caused by circuit oscillation caused by excessive switching spikes is solved by using high-frequency modeling and starting from interference source suppression.(2)Secondly,the impedance of the interference lines is another major factor in the analysis of electromagnetic interference.In this paper,the impedance spectrum is obtained by extracting the electromagnetic interference noise source through the insertion loss,and the port impedance model is established to reflect the high frequency parasitic circuit characteristics of the power supply.In the process of extracting modeling parameters,genetic algorithm and annealing algorithm are used to calculate the model,and the extraction of the inline impedance on the high-power power supply is completed.In comparison to the existing offline test method,the method adopted in this article can extract the impedance spectrum of the EMI source with greater accuracy.(3)Finally,this document designs the EMI filter and optimizes the electromagnetic compatibility of the designed PSU.After completing the above calculation and test,the EMI filter design method for throttle feed is proposed.Under the calculated parameters,the insertion loss is analyzed and the insertion loss meets the design requirements for the power supply.The existing filter design method is an iterative design of filter devices based on the known noise spectrum,which requires great manpower and design costs,and the design cycle is longer.The design method based on impedance matching proposed in this paper not only optimizes the design process of EMI filter,but also completes the verification experiment on the accelerator power supply,and finally forms a general design method of EMI filter for accelerator power supply.