| Abstract: | The magnetic flux inside a synchronous generator is regarded as a characteristic that dominates a generator operation. This paper develops a simple model of a synchronous generator by which it is possible to easily estimate an air-gap flux as well as electrical characteristics. The air-gap flux density can be related to a permeance and a magnetomotive force (mmf) along its magnetic path by the Ampere's laws. These relations are used in this paper. We estimate the distribution of the permeance along the air-gap and the mmf profiles of the stator and the rotor of a 6 kVA scaled-down tested synchronous generator. From these estimated profiles, the relations among the air-gap flux, field current, and armature current are represented by a linear equation system. Consequently, the static electrical and magnetic characteristics of a synchronous generator can be estimated by giving only field exciting voltage and load impedance. The distributions of the air-gap flux density and waveforms of the field and armature currents are simulated for various unbalanced-load conditions. The simulated results well agree with experimental ones not only for fundamental components but also for higher harmonic components. Therefore, our method, based on the permeance profile, is available to calculate the static characteristics of synchronous generators. |
