The Research Of Isolation Circuit In J-TEXT And Design Standardized Equipment

During the J-TEXT tokamak discharge,it will form a very complex electromagnetic environment around the device,the central control system and many subsystems which distributed around the J-TEXT machine will produce and receive lots of control signals,trigger signals,real-time diagnosis signals,etc.Thus,signals are vulnerable to interference.In order to ensure data acquisition system could get real and effective experimental signal data,it is necessary to research the conditioning-technology such as isolation and conversion in the tokamak data acquisition system.According to the basic requirements of J-TEXT device signal transmission of anti-jamming,this paper study on the digital signal isolation technology,digital signal optical fiber transmission technology,high frequency analog signal isolation technology,and design modular,intelligent circuit equipment.In this paper,in order to simplify the network topology,author design 32 channel electro-optical conversion circuit of sequential control by using Ethernet to communicate with each other,and design single channel electro-optical conversion module so that it can conveniently installed in distributed diagnosis acquisition system.Adding the digital isolation circuit to the electro-optical conversion circuit will reduce the possibility of mistake trigger.The transmission delay is less than 190 ns in the whole circuit of digital signal optical fiber transmission system,the circuit output current is 400 mA and it can improve the circuit load capacity.If the acquisition cards are directly connected to the sensor,the high voltage The high voltage produced by disruption will damage acquisition cards.Adding the analog signal isolating can effectively protect the acquisition cards.According to different signal diagnostic characteristic frequency,this paper study on both low frequency and high frequency signal isolation technology.Author have designed two power supply modes for low frequency analog circuit which bandwidth is 50 kHz and nonlinearity is lower than 0.5% and simulated high frequency analog circuit which bandwidth is 40 MHz kHz and nonlinearity is lower than 1%.This paper according to demands of signal conditioning modular equipment installation have designed standard equipment and have completed multi-function slot chassis,backplane PCB and various signal conditioning module standardization.Thus the signal conditioning circuit can be more conveniently installed.Standardized design rules in order to avoid repeated design ao that it can reduce the production cycle time and the cost.