Techniques for Designing HFAC Power Distribution Systems; Power Conversion and Distribution

Abstract

Modern power distribution systems (PDS) utilize multiple converters, making power flow undergo several conversions between source and the load. Use of high frequency AC (HFAC) in PDSs eliminates a few stages of converters in addition to the smaller sized capacitors and inductors being used; making the converters much lighter in weight offering a variety of solutions for the weight critical applications such as spacecraft, aircraft and electric vehicle onboard PDSs. HFAC converters with resonant filters have been widely used in the past despite of being tuned to a single frequency. Thus, the variable frequency operation as well as parallel connection of multiple converters had been less efficient. This part of the research work focusses on development of a bi-directional AC-AC converter that could work within a range of grid parameters. The proposed two-stage converter constructed with wide bandgap power switches, a high-performance microcontroller, low-pass filters which operates at high switching frequencies provide the desired variable frequency and voltage operation capability. A major drawback in HFAC PDS had been the excessive power loss and voltage drop due to skin effect and proximity effect of conductors. This part of the research work investigates the development of new cable types with hollow core cross-sections. This would minimize skin effect losses by shifting much of the conducting material to the skin depth, keeping the weight increase to a minimal. Feasibility studies performed using PSCAD software showed improved performance of cables upto 100kHz; enabling using such as in wireless power transmission applications.