Doctoral Dissertation
Circuit techniques for compact and lightweight high-voltage DC power supplies
High voltage power supplies are essential in scientific, medical, environmental, security, and robotics fields. The size and weight of the circuit often limit the portability of the system and the range of applications. Smaller, faster, and more efficient power supplies will enable new scientific and commercial advances. My thesis presents circuit techniques to improve the performance of high voltage dc generators. A traditional way of generating a high dc voltage involves a step-up transformer built with a bulky magnetic core and a Cockcroft-Walton voltage multiplier, assembled on an FR4 printed circuit board and sometimes potted in insulating epoxy. Recently, many advances are being made in wide-bandgap semiconductor devices, sub-millimeter size passive components, and high-frequency circuit design methodologies. Those technological developments enable new techniques to design a high voltage power supply. This dissertation presents several new ways to build a high voltage dc generator: a planar PCB transformer that simplifies high-voltage isolation transformer design, a new voltage multiplier topology that exhibits less output voltage drop than the traditional Cockcroft-Walton multiplier, and foldable converters assembled on a flexible PCB to miniaturize kilovolts-level power supplies down to the sub-centimeter scale. My dissertation includes the motivation for investigating each of those circuit techniques and relevant power supply designs as well as application examples. I experimentally validate that by using those techniques appropriately, one can build a smaller and lighter power supply that exceeds traditional boundaries of high voltage generator performance.