High-Performance Pulsed Power System Based on Solid-State Switch: Design, Implementation, and Applications Dissertation note: Thesis (Ph.D.) - Korea University of Science and Technology

ABSTRACT
 The recent proliferation of applications requiring pulsed power at a high repetition rate has led to greater research focus on the development of solid-state pulsed power systems that exploit the advantages of semiconductor switches, including the ease of control over output pulses, and the high repetition rate and long life span offered by such devices. However, to realize practical solid-state pulsed power systems, several limitations must first be overcome such as the difficulty in series operation for semiconductor devices and high-voltage energy charging with high efficiency. In addition, the importance of the semiconductor devices protection circuit against arcing condition in guaranteeing reliable operation cannot be overemphasized. This study explored the design, implementation, and applications of a high-performance solid-state pulsed power system by addressing each of the aforementioned difficulties. 　 * A thesis submitted to committee of the University of Science and Technology in a partial fulfillment of the requirement for the degree of Doctor of Philosophy in Electrical Engineering conferred in April 2011 The proposed design is applicable to a variety of applications owing to its several distinctive features such as flexible output voltage, pulse width, and repetition rate with stabilized arcing protection. Charging efficiency is addressed using a novel, compact, soft-switching technology based hybrid converter that offers high efficiency over a wide range of load conditions and controllable output voltages. A voltage-doubler rectifier and a transformer with multiple secondary windings are included in the system for parallel charging of multiple capacitors simultaneously from one charging inverter. It has been verified that the developed charger can be effectively applicable to the proposed solid-state pulsed power system. Through the study, a new series connection method is proposed based on power cell units with simple gate drive circuits operating with a pulse control loop. The proposed pulse generator affords not only high reliability and efficiency but also high repetition rate and fast rising time. This dissertation describes the detailed design procedure for the developed solid-state pulsed power system made of a high-efficiency capacitor charger and a highly reliable pulse generator. Experimental results are included verifying the performance characteristics and novelty of the proposed solid-state pulsed power system with the maximum pulse repetition rate of 50 kpps, total efficiency of 92 %, output pulse voltage of 0–10 kV, and pulse width of 1–10 μs. Finally, it was confirmed that implemented solid-state pulsed power system can be effectively applied to a plasma source ion implantation for diamond like carbon coating and a plasma immersion ion milling for nano scaled mold. The proposed system can be applied to a wide range of industry system such as pollution control systems for water and gas treatment due to its flexibility.