Core-Saturation Control for Tunable Pulse Widths in Thyristor-Switched Linear Transformer Drivers

Linear transformer drivers (LTDs) offer significant advantages for pulsed power applications, but solid-state implementations typically rely on MOSFETs or IGBTs that impose current handling limitations. Thyristors provide substantially higher current handling capability compared to other solid-state switches, making them highly attractive for high-current pulsed-power LTDs. However, because they cannot be turned off through gate control, conventional pulse-width modulation is not possible, limiting their use in applications that require tunable pulse durations. This paper presents a method for achieving pulse width control in thyristor-switched LTDs by exploiting controlled magnetic core saturation. By varying the magnetic reset applied to the cores prior to discharge, the available flux swing and the resulting output pulse duration can be precisely controlled. A 10-stage thyristor-switched LTD was designed and constructed to validate this approach, utilizing SP245-03 thyristors and nanocrystalline magnetic cores. The results demonstrate continuous pulse width control from 540 ns to 1.7 µs at nominal 10 kV output voltage, with the output pulse duration exhibiting a linear relationship with applied reset time up to core saturation. The measured maximum pulse width agrees well with theoretical predictions based on Faraday’s law. This work demonstrates that thyristor-based LTDs can achieve flexible pulse width modulation while benefiting from the higher current ratings these devices offer, enabling new design possibilities for high-current pulsed power systems.