Achievement Of A Prototype Of Pulse Rectifier System And Study Of Its Control Method

With the development of the scientific and technological research, the traditionalcontinuous magnetic field and traditional pulsed magnetic field is difficult to meet some ofthe requirements of the research. Continuous magnetic field has the advantages of longduration and small fluctuation, but it’s difficult to make the field strength high. Pulsedmagnetic field can reach the higher field strength but the pulse is instability anduncontrollability. Then the High-Stability Flat-Top of the Long-Pulse magnetic field hasboth the advantages of them, it has become more and more important in the modernscientific research. As a reliable magnet power, the pulse-generator power supply systemhas been used, and the rectifier system is an important part of the power system.The National High Magnetic Field Center, which is located in Wuhan, is devoted toconstruct a device to produce The High-Stability Flat-Top of the Long-Pulse MagneticField. The device uses the power supply system of a pulse generator with thephase-controlled rectifier. The design of the pulse rectifier and the control strategy of it willhave an important impact on the magnetic field waveform. To reduce the whole deviceproportionably and simulate the operation conditions, this paper designs and realizes aprototype of the rectifier system in the magnet power, in order to study the control method.This prototype is powered by the380V-power network to realize12-pulse rectifier. Usingan inverter, it can simulate the frequency-drop characteristic when the pulse-generator isrunning.In the aspect of implementation of the rectifier prototype, this paper designs theconfiguration of the pulse rectifier prototype and analyzes its working process, and designsthe components of each parameter. What’s more, it also discusses performance of differentselection of structure type of the rectifier transformer. When the rectifiers are in parallelform, it analyzes the selection of the reactor to reduce loop-current. It also designs and teststhe rectifier transformer and discusses the design of dual-coil magnet load. Finally, itcompletes the construction of the entire prototype system.In the aspect of control method of the rectifier prototype, this paper describes the maincomponents of the rectifier control system. it mainly analyzes rectifier PI control and discusses software phase-locked with the zero-crossing comparison method andinstantaneous reactive theory method. Then it makes an improvement of the traditionalinstantaneous reactive theory method in the case of fixed frequency. It introduces thehardware trigger board which is made by HuiWei Company in ZuZhou, and designs a DSPboard for software control, discussing the interface circuit of DSP and two AD7606chips.Besides, it also designs the program for software phase-locking.By using SIMULINK, it builds a12-pulsed rectifier model and the softwarephase-locking model with the instantaneous reactive theory method which is improved,simulating the control strategies and operating conditions, analyzing the waveform anddata. Then some experiments are performed by using the hardware trigger board, itcompares the rectification characteristics of fixed-frequency and time-varying frequencyand discusses the difference of the performance of different PI parameters. Finally itdiscusses the spatial interference of rectifying performance in the experiments.In a word, this paper designs, analysis and does some practical tests of the rectifierprototype, this prototype has important significance to the control method of the actualpulse generator power supply system.