The design of a low-inductance folding MOV structure for the generation of high voltage microsecond quasi-square pulses

Abstract

Metal-oxide varistors (MOVs) have been applied to the pulsed power field for the generation of quasi-square pulses due to their nonlinear voltage-current characteristics. The varistor voltage of a single MOV is limited. Multiple MOVs in series are promising to be used to stabilize high voltage pulses and therefore to produce quasi-square pulses. A low-inductance folding MOV structure for the generation of high voltage microsecond quasi-square pulses is designed and numerically studied in this paper. Circuit simulations have been carried out to verify the shaping characteristics of MOVs and the influence of the MOV column inductance on the output waveforms is analyzed. A coaxial evolute structure of MOV in series has been designed and optimized to increase the insulation level of the MOV column while minimizing its inductance through simulations in CST. Furthermore, a 500kV-level microsecond pulse generator based on the multiple MOVs with coaxial evolute structure has been designed and verified with simulation. The results indicate that a high voltage pulse with amplitude of 500 kV and pulse width of 1 μs can be obtained on the load of about 50 Ω. Without pulse forming lines, this MOV based generator has the advantages of simple design and compact construction, which is promising to be used as a compact long pulse driving source in many fields, such as corona plasma generation, industrial dedusting, and medical disinfection.