Open AccessAnalytical prediction of optimal split ratio of consequent‐pole permanent magnet machines
Author(s) -
Li Jian,
Wang Kai,
Li Feng
Publication year - 2018
Publication title -
iet electric power applications
Language(s) - English
Resource type - Journals
ISSN - 1751-8679
DOI - 10.1049/iet-epa.2017.0431
Subject(s) - stator , magnet , torque , aspect ratio (aeronautics) , arc (geometry) , torque density , diameter ratio , materials science , density ratio , mechanics , control theory (sociology) , flux (metallurgy) , physics , mathematics , geometry , engineering , mechanical engineering , computer science , composite material , thermodynamics , control (management) , artificial intelligence , metallurgy
For consequent‐pole permanent magnet (CPM) machines, the permanent magnet (PM)‐arc ratio and split ratio have great influence on the output torque. This study establishes general relationship of the output torque/torque density with PM‐arc ratio and split ratio considering the effects of slot/pole number combinations and the tooth‐tips. In addition, both the optimal PM‐arc ratio and split ratio for maximising the torque density are analytically derived and confirmed by finite‐element analysis. It is found that the optimal PM‐arc ratio is determined by the ratio of the airgap length to the PM thickness. It is demonstrated that the optimal split ratio depends on the ratio of average airgap flux density below one slot to maximum flux density in the stator iron k B γ and the number of slots for the slots per pole q ≤ 1.5or the number of poles for q > 1.5 . Moreover, it is found that the optimal split ratio decreases with the ratio k B γ , which depends on the PM thickness and PM‐arc ratio, and it is reduced when the effect of the stator tooth‐tips is taken into consideration. The experimental results on the 12‐slot/10‐pole CPM machine are given to verify these analyses.