Series Switches Module With Ultralow Parasitic Inductance for Pulsed Power Applications

The series parasitic inductance of semiconductor switches can lead to a slower rise time in the output of high-voltage nanosecond pulsed power generators. This article proposes a series structure with ultralow parasitic inductance, which separates the switch substrate from the series substrate based on the existing planar low-inductance series structure. By converting the voltage withstand requirement of the switch substrate from the total series withstand voltage to the single-stage switch withstand voltage, the substrate thickness is significantly reduced, thereby lowering the parasitic inductance of the switch unit. The series length is also changed from the switch length to the switch thickness, significantly shortening the current path and reducing the series parasitic inductance. A six-stage ultralow-inductance switches module using transistor outline leadless (TOLL)-packaged MOS controlled thyristors (MCTs) was designed, with a parasitic inductance of only 7 nH. Compared to the planar series structure, the parasitic inductance is reduced by 36%, and the charging voltage over-shoot is reduced by 80%. A pulsed power generator based on a blumlein pulse forming network (BPFN) was designed, which achieved a quasi-square wave pulse current with a top value of 1.3 kA and a rise time of 18.6 ns on a$7.5\Omega $load at charging voltage 9 kV, representing an improvement of 6.6 ns compared to the planar structure.