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Aircraft electrical power consumption has dramatically increased in recent years. Technological advancements have led to the replacement of traditional hydraulic and pneumatic systems with electrically powered devices. In addition, new functions such as deicing and entertainment systems have been added, which further increases the demand for electrical power. As power needs increase, voltage or current, or both, must be increased. Increased current can be the least desirable result as it leads to larger and heavier wires. To mitigate the issue of wire weight and distribution losses, the latest “More Electric Aircraft” have adopted 230 V ac as the main power bus voltage. However, this presents a problem as a significant amount of existing electrical aircraft equipment (actuators, pumps, etc.) have been designed to use 270 V dc power, which is obtained by a direct rectification of 115 V ac power. Two hundred seventy volts dc cannot be as simply produced from a 230 V ac bus.

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.

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.

This paper describes the challenges inherent in developing high power (>100kW) AC-DC converters for aerospace applications. Various technologies and topologies were considered, analyzed and rated, with an optimum design being chosen. Details regarding power quality, magnetics design, and thermal management are discussed. Performance results from demonstration hardware are provided, including power quality, regulation, efficiency (98%) and temperature results.

This paper summarizes the performance requirements of existing and next generation regulated TRUs. The presented solution is compatible in weight, reliability and cost with a standard unregulated TRU. It also has the overload capability of an unregulated TRU. Additionally, it has well regulated (line and load) 28 Vdc output from 0 to 100 percent rated load. Performance and test data of a resulting 400 Amp Regulated TRU are addressed in the paper.