A High-voltage,Long-pulse Width Pulse Generator Based On Metal Oxide Varistors

Pulse power technology is widely used in the fields of national defense and civil industry.Long pulse width and system compactness are important directions of the development of pulse power technology.With the rapid development of the semiconductor industry,the metal oxide varistor(MOV)has nonlinear V-I characteristics,energy absorptive capacity,and fast response time.The pulse formation technology based on MOVs is aroused widespread attention from researchers,which has been verified to be an effective way to generate high-voltage quasi-square pulses in recent years.In this thesis,a long-pulse width pulse generator based on metal oxide varistors has been constructed and tested.The main works of the thesis are shown as follows:1.The designing and optimization of MOV folding structureThe MOV coaxial involute folding structure is designed.The electromagnetic simulations in CST are carried out which verify that the new structure can avoid excessive local field strength and improve the insulation capacity through quasi-electrostatic field simulation and reduce inductance through static magnetic field simulation.The optimization is carried out,and the optimal structure is obtained under the premise of ensuring insulation capacity,whose inductance is reduced from 1 μH to 225 n H and the insulation capability is significantly improved.2.The analysis of flat-top compensation schemeThe inductance of the MOV branch is unavoidable,which will cause a flat-top droop in the output waveform.Then a flat-top compensation scheme has been proposed to improve the waveform flat-top.The basic theories of network synthesisn is introduced,including the network feasibility judgments and general synthesis methods.The general analysis methods and several conclusions of Guillemin network are summarized.The flattop compensation scheme,including design principles and circuit parameter determination,is proposed.The PFN-MOV circuit is verified that can effectively improve the quality of the flat top and the energy efficiency of the device by circuit simulations.3.The construction and testing of a long-pulse width pulse generator based on metal oxide varistorsA Marx generator is set up,which the internal parameters are measured through short-circuit discharge experiment.With a charging voltage of 55 k V,a pulse with peak voltage of 480 k V,pulse width of 1.2 μs,rising time of less than 100 ns is obtained on the water load,which verify the working state and the consistency with the circuit simulation results.The experiments of the long-pulse width pulse generator based on metal oxide varistors is carried out,and a quasi-square pulse is obtained on a 50 Ω water load,with voltage amplitude of 510 k V,pulse width greater than 800 ns,rise time of less than 50 ns,and flat top of about 600 ns...