The Development Of All Solid-state Mixed Pulse Generator Based On Marx And LTD Topologies

In recent years,the application of pulse power technology has penetrated into many fields such as biomedicine,food processing,environmental protection,plasma generation,industrial application and scientific research.Different requirements for pulse generators are needed in different fields,but the overall trend is the requirement of pulse source with a higher output voltage,faster rising edge and higher repetition frequency,at the same time,with flexible adjustment way and wide scope of application.Firstly,in this paper,the basic working principles of Marx and LTD are analyzed,and the working state of Marx circuit is analyzed in detail.Then the author introduces the mixed pulse generator based on Marx and LTD topologies,which can adapt variable load,is easy to modular design,reduce requirements for isolating power supply module and the synchronicity of trigger signals.The basic working principle pattern of the mixed pulse generator is analyzed,and the simulation verification is carried out by PSpice software.In order to avoid the misoperation of the switching device and reduce the switching loss,the design method and optimization measures of the driving circuit parameters are analyzed and the correctness of the analysis is verified by simulation.Then,the control system including control board,lower FPGA program,computer software and serial liquid crystal display for the mixed pulse generator is designed.The control board,which can generate 12 control signals,adopts FPGA as the main control chip.The FPGA program,which mainly includes serial communications,parameter conversion and selection,pulse generation,phase locked loop modules,is designed by Verilog HDL.The computer software is designed with Qt framework.The serial port LCD control software is also designed.The control system can not only generate a certain number of control signals with variable pulse width and cycle,but also can change the rise time and fall time of the mixed pulse generator with the function of phase locked loop.In addition to producing the same repetitive pulse,the control system can also generate a series of pulse with variable parameters which has great application value in the field of biomedical science.Finally,the key components of the mixed pulse source such as switch device,energy storage capacitor,diode,driving chip,power supply module and magnetic core are calculated and selected.The developed mixed pulse generator contains 4 LTD modules,and each LTD module is composed of a 3-level Marx circuit.The mixed pulse generator can generate pulse with amplitude 0~8 kV,pulse width 60~160 ns with step length to 1 ns,repeat frequency of 1 kHz,rising time about 10 ns.The output pulse rising and falling edge can be changed with phase-shift control signal generated by FPGA with PLL.The generator adopts modularization design,which can improve the maximum output voltage by increasing the number of modules.The mixed pulse generator designed in this paper is of high amplitude,narrow pulse width,fast forward edge and flexible control can be widely applied in various fields.