Thermal Analysis of Brushless Doubly Fed Induction Machine

Brushless Doubly Fed Induction Machine (BDFIM) is a different type generator designed for energy production especially in offshore. A number of features of BDFIM which are frequency control and lack of brush make this generator advantageous energy generation from wind power. Although BDFIM owns some advantages, this machine is not commercially produced and it must be developed because of low efficiency and complex structure. Its design and analysis have been carried out to fix these disadvantages. Design of electrical machine is relevant to electromagnetic and thermal analysis. In this paper, thermal analysis of 3.2 MW BDFIM which is one of the most serious matter influencing the outputs is examined. Stator of BDFIM consists of two windings and they have different pole numbers and BDFIM owns nested loop squirrel cage rotor, consequently thermal analysis of BDFIM is more complex than other machines. In this paper, thermal resistances, capacitances and losses of BDFIM are calculated and transient and steady state thermal simulation is carried out with MATLAB/Simulink. In addition, flux density and flux lines of BDFIM are examined in Ansoft/MAXWELL to better evaluate thermal behavior.