Autotransformer Rectifier Units (ATRU)
Power electronics is playing a leading role enabling the replacement of former mechanical, pneumatic and hydraulical systems in the next and future generation more-electric aircrafts, a paradigm shift affecting all commercial and military aircraft development. The major drive for the design and development of aircraft power electronics converters is weight reduction; simply put, the lighter the aircraft the larger the payload it can carry. Within the realm of power electronics, so far passive diode-based solutions have been chosen whenever possible due to their lighter weight and utter simplicity. CPES has actively participated in the development of multi-pulse ac-dc power conversion developing 18-pulse autotransformer rectifier units (ATRU) under sponsorship from THALES Avionics Electrical Systems. Specifically two types of ATRU were developed, namely symmetric and asymmetric. Symmetric ATRU topologies have already been adopted by the industry for different ac-dc applications following CPES proposals, however the adoption of the 40% lighter asymmetric ATRU types developed by CPES still depends on the final manufacturing capability of the industry, since this topology is significantly more sensitive to the autotransformer parasitics to leakage inductance especially. ATRU converters have also been adopted in low power appliance applications acting as passive filters for six-pulse diode bridge rectifiers, and are expected to enter operation in non-regenerative motor drive and other three-phase ac-dc power conversion applications.