Design Study Of High-voltage Nanosecond Pulse Generation System

Pulsed electric fields(PEFs)are increasingly being used in the medical field,particularly with the "nanoknife" playing a significant role in tumor treatment.However,there are still limitations with the current nanoknife technology in inhibiting tumor metastasis and recurrence.In this regard,both domestic and international scholars have found that nanosecond pulse induction technology can significantly improve the efficacy of cancer treatment.However,the current high-voltage pulse technology faces technical bottlenecks in achieving ultra-short pulse implementation,specifically due to the lack of a high-voltage nanosecond pulse generator capable of producing pulse amplitudes of over 10 k V and flexible pulse widths ranging from 30 ns to 500 ns.Based on this,this paper carries out the following research on how to realize the high voltage nanosecond pulse generator:Firstly,three existing high-voltage pulse generation technologies are analyzed and compared in the design of circuit architecture.Marx circuit with capacitive discharge is selected to meet the two requirements of flexible high voltage and pulse width,and a series and parallel array of SiC MOSFET is innovatively introduced to improve the voltage and current level of Marx circuit,so as to improve the output efficiency of the pulse generator.In the study of the mechanism of capacitor discharge circuit,it is found that the equivalent parasitic inductance of the whole circuit will seriously affect the pulse width,and the requirement of controlling the parasitic inductance of the whole circuit within 150 n H is put forward.Secondly,the finite element software is used to analyze the package structure of three power semiconductor modules,and the optimal effect of the plate package structure in reducing the parasitic inductance of the package module is verified.Based on the plate structure,the Marx circuit power module is designed.The parasitic inductance of a single Marx circuit is 14.87 n H,and the equivalent parasitic inductance of the whole circuit of the pulse generator is 115.2n H.The expansibility and portability of the high-voltage nanosecond pulse generator are improved,and the parasitic inductance of the whole pulse generator is further guaranteed to be within the index.Finally,Simulation results show that when the input DC voltage is 3k V and 4Marx circuits are cascaded,the output pulse amplitude of the pulse generator is above11.5k V,the pulse width is between 30 ns and 500 ns,and the voltage output efficiency reaches over 95%.The power chip loss of the unit Marx circuit module is only26.09℃ in 100 operating cycles at an ambient temperature of 25℃.