Overview of Multiphase Power Converters for Aerospace Applications 2008-01-2878
Aircraft electrical power is generated in the form of three-phase alternating current. Most electrical loads require DC power to operate; therefore the conversion from AC to DC power is required. The direct rectification of 3-phase AC power into DC power is simple and straightforward; however, it creates unacceptable levels of current distortion. Multiphase power conversion is one of several technologies capable of AC to DC power conversion with low distortion levels that meet aerospace power quality standards.
A typical autotransformer based multiphase converter contains two major functional blocks: a multiphase autotransformer and rectifier. Autotransformer rectifier units (ATRUs) have a low part count, and are highly reliable. There are only a few low frequency switching components with this topology, so EMI emissions are relatively low when compared to high frequency switching techniques.
Where voltage regulation is not critical, multiphase converters offer a reliable, low weight, and low cost solution meeting demands of today's aerospace application needs.
This paper reviews the principles of multiphase power conversion technology. The following topics are covered in detail.
12-pulse, 18-pulse, and 30-pulse converters
Current harmonic spectrums and filtering
The effects of leakage inductance and power source phase sequence on power quality
Trade offs between topology selections, performance, and converter weight
Examples of converter modeling and performance data from selected designs are included in this paper.