Influence of Inverter Loads on the Airgap Flux of Aerospace Homopolar Alternators

In this paper the effects of the time harmonics on the output voltage are investigated. Instead of a complete analysis, the waveshape of the line current is considered as recorded on an oscilloscope when the alternator supplies an inverter. The minimum airgap induction occurs when the magnetomotive forces of the fifth and seventh time harmonic oppose the field excitation. The reduction in the amplitude of the fundamental of the airgap induction caused by the time harmonics was found to be of the order of fifteen to twenty percent for a typical cyclo-inverter load.