
23-6 Power Electronics and Motor Drives
Systems, with permanent magnet generators (PMG), which are mechanically coupled on the same
sha as DFIG, and the electric coupling of PMG stator with DFIG rotor is made by power converter are
already known and described [10,11] (Figure 23.5). e problem of initial excitation is eliminated, but
the possible delivered power does not exceed the power of DFIG stator. For over-synchronous speed the
electrical power is provided to the PMG, which operates as a motor, and only the DFIG stator power is
available.
Combination of classical DFIG topology, and fractional power PMG, coupled on the same sha,
used