Performance analysis of doubly fed brushless machine with cage rotor

Due to the complexity of structure as well electromagnetic coupling, accurate calculation of self and mutual inductances of stator and rotor windings for doubly fed brushless machine (DFBM) with cage rotor is difficult which is likely to lead to inaccuracy in performance analysis. In this paper, a method of parameter calculation and performance simulation based on combined magnetic field analysis with circuit model for cage rotor DFBM is introduced. The determination method of parameters based on magnetic field analysis can take the influence of teeth and slots as well the saturation effect into account; and the performance simulation based on the circuit model can consider easily the different operation modes and control strategies of the DFBM. As an example, the parameter determination and performance simulation for a 75kW cage rotor DFBM with 10-pole stator power winding and 6-pole control winding are introduced in detail. The comparisons of simulated starting and load characteristics with the tested results of the DFBM verify the validity of the proposed method of parameter determination and performance analysis.