24-09-2021, 06:11 PM
Hi Jeffrey, indeed polyphase rectification (up to 30 phase) is common on some aircraft systems to improve power factor and help reduce EMC effects of "current chopping").
While working on inverter and converter systems for the A400M we used 18phase rectification from the aircraft 115V 380 to 620Hz bus. This frequency wild system was used so that alternators were directly coupled to the turbo prop engines, saving the weight and expense or the normal variable speed drive.
18 phase gave a good balance between cost and efficiency due to losses in the extra magnetics. We did often wonder if the additional mass of the extra magnetics was greater than the weight saved from the variable speed drives.
Somewhere I have a detailed table of the various phase numbers (all triplen) and the advantages, I'll post it if it can be found
Ed
While working on inverter and converter systems for the A400M we used 18phase rectification from the aircraft 115V 380 to 620Hz bus. This frequency wild system was used so that alternators were directly coupled to the turbo prop engines, saving the weight and expense or the normal variable speed drive.
18 phase gave a good balance between cost and efficiency due to losses in the extra magnetics. We did often wonder if the additional mass of the extra magnetics was greater than the weight saved from the variable speed drives.
Somewhere I have a detailed table of the various phase numbers (all triplen) and the advantages, I'll post it if it can be found
Ed
