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.

Publications

A Low-Ripple High-Frequency High-Voltage Power Supply for Ion Pumps ∙ IEEE APEC ∙ 2023
Low-Ripple High-Voltage DC Generation Using a Serially Segmented Multiphase Voltage Multiplier ∙ IEEE ECCE ∙ 2020
Lightweight High Voltage Generator for Untethered Electroadhesive Perching of Micro Air Vehicles ∙ IEEE Robotics and Automation Letters ∙ 2020
Optimized Design of Multi-MHz Frequency Isolated Auxiliary Power Supply for Gate Drivers in Medium-Voltage Converters ∙ IEEE TPEL ∙ 2020
Miniature High-Voltage DC-DC Power Converters for Space and Micro-Robotic Applications ∙ IEEE ECCE ∙ 2019
A Compact 45 V-to-54 kV Modular DC-DC Converter ∙ IEEE COMPEL ∙ 2019
A Hybrid Cockcroft–Walton/Dickson Multiplier for High Voltage Generation ∙ IEEE TPEL ∙ 2019
Empirical Circuit Model for Output Capacitance Losses in Silicon Carbide Power Devices ∙ IEEE APEC ∙ 2019
Estimating the Reliability of Series-Connected Schottky Diodes for High-Frequency Rectification ∙ IEEE COMPEL ∙ 2018
FPGA-based Dynamic Duty Cycle and Frequency Controller for a Class-E2 DC-DC Converter ∙ IPEC-Niigata (ECCE Asia) ∙ 2018
60 V-to-35 kV input-parallel output-series DC-DC converter using multi-level class-DE rectifiers ∙ IEEE APEC ∙ 2018
Duty Cycle and Frequency Modulations in Class-E DC–DC Converters for a Wide Range of Input and Output Voltages ∙ IEEE TPEL ∙ 2018
COSS Losses in 600 V GaN Power Semiconductors in Soft-Switched, High- and Very-High-Frequency Power Converters ∙ IEEE TPEL ∙ 2018
A portable electrostatic precipitator to reduce respiratory death in rural environments ∙ IEEE COMPEL ∙ 2017
Isolated resonant DC-DC converters with a loosely coupled transformer ∙ IEEE COMPEL ∙ 2017
Power loss of GaN transistor reverse diodes in a high frequency high voltage resonant rectifier ∙ IEEE APEC ∙ 2017
Design of a Class-DE Rectifier with Shunt Inductance and Nonlinear Capacitance for High-Voltage Conversion ∙ IEEE TPEL ∙ 2017
A design methodology for class-D resonant rectifier with parallel LC tank ∙ IEEE COMPEL ∙ 2016

Patents

Apparatuses and methods involving power conversion using multiple rectifier circuits ∙ US Patent 11,228,252 ∙ 2022