Magnetic Field Distribution and Operating Characteristics of a Hybrid Excitation Generator Based on Integrated Brushless Excitation

In general, the brushless wound rotor hybrid excitation synchronous generator (HESG) needs a separate exciter. In this paper, a novel integrated brushless excitation HESG (IBE HESG) is developed by integrating the excitation section into the iron core of wound rotor HESG. Compared with the conventional brushless excitation method, the axial length of the IBE HESG is shorter and the original topology of the wound rotor generator is not changed. The excitation section has two sets of windings: stator excitation windings and rotor armature windings. The stator excitation windings are installed in the stator slots evenly. The static excitation field is established by the dc excitation current of the stator excitation windings. The rotor armature windings are buried in the rotor armature slots around the rotor. The static excitation field induces a voltage in the three-phase rotor armature windings and supplies the dc current to the rotor excitation windings through a rotating rectifier on the rotor. The magnetic field distribution is analyzed by the frozen permeability method to decouple the multimagnetic circuits. Also, the influencing factors of excitation efficiency are studied and the parameters of the IBE HESG are obtained to achieve a reasonable excitation characteristic. Finally, the theoretical analysis is confirmed by the experiments on a 1.5 kVA/50 Hz prototype generator. The results show that the output power can be regulated over a wide range.