Research On Novel Aviation AC/DC Bus Interface Converters

In the modern aircrafts, a variety of secondary energy, such as hydraulic, pneumatic and electricity,makes a huge risk for the aircraft power supply system and threaten the safty and reliability of theflight. In the recent years, the development of the power electronics and electronic material make itpossible for the union of secondary energy and promote the development of more-electric andall-electric aircrafts.The development trend of more-electric and all-electric aircrafts results in the improvement of theAC/DC rate voltage and has raised more new demands for the aviation AC/DC bus interfaceconverters. AC/DC bus interface converter is to realize high voltage AC (HVAC) bus to high voltageDC (HVDC) bus, demanding for high safty and reliability, high power factor, high power density andhigh voltage utilization. DC-DC bus interface converter is to cnvert HVDC to low voltage DC (LVDC)bus, also demanding for high safty and reliability, high power density and high efficiency.Based on the application conditions and design demands, this paper selects the single-stageBoost rectifier——three-phase three-wire three-level rectifier with simple structure as AC/DC businterface converter after detail comparison and analyzes the influence of variety control strategies onthe rectifier performance index from the basic modulated wave, then proposes the nonlinear controlstrategy based on interval truncation. This control strategy can improve the voltage utilization on thepremise of high power factor to simplify the design of the secondary converter. For DC/DC businterface converter applied to high-voltage input low-voltage high-current output, this paper choosesthe non clamped diodes and non flying capacitor four switches three level DC/DC converter. And theintegrated magenetic double-current-rectification technology is adapted to improve the system powerdensity. In order to improve the safety and reliability of the power supply system, this paper gives adetail analysis on the voltage unbalance among the capacitors caused by the asysmetrical main circuit,control and driving circuits in the practical operations. Two control quantities, duty cycle and phaseshift of positive and negative half cycles are found to realize the control of the capacitor voltage. Thedual stage control is also applied to the control strategy to decouple the modulated process.Finally, a three phase230V/400Hz input28V/100A output interface converters prototype isdesigned and built in the laboratory. The experimental results are given and analyzed to verify thecontrol strategy for the rectifier and the capacitor voltage control strategy for the converter.