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This paper addresses the challenges inherent in meeting the new power quality requirements needed on today's more electric aircraft. Technologies that generate low total distortion and minimize individual current harmonics are discussed. This paper describes several different converter topologies that are capable of meeting the power quality requirements in aerospace applications. Various multi-phase passive and active practical approaches to improving power quality are considered, analyzed and rated. The advantages and disadvantages of each are discussed. Performance results from demonstration hardware are provided, including power quality, regulation, efficiency, and reliability.

1 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.