Procedures to Determine Inductances of Permanent Magnet Generators

Electrical machines are designed from theoretical concepts and the proof that their operational characteristics meet the specifications is tested in specialized laboratories using internationally accepted standards. However, whenever permanent magnet synchronous machines (PMSG) need to be tested, global standards become limited due to the absence of excitation field control in these machines. To evaluate the performance of large wind generators, further studies using equivalency testing methodology should be performed so as to minimize the structural limitations of laboratories. These limitations make it difficult and challenging to perform the experimental characterization of a great power permanent magnet synchronous generator, the prototype machine for use in wind generation. In this work, different testing methodologies were evaluated. For determining the inductance characteristics, the current step response of DC voltage method was adapted. The machine response variation according to the supply frequency and changes in its load was also assessed. Results were validated and compared with the partial use of some standard tests. The machine characterization by testing temperature rise was made using the back-to-back method, and the machine yield was tested by the segregation losses method. The results indicate the feasibility of using the procedures discussed in the present study to characterize the PMSG.