A Theoretical and Practical Study of the Guy-Type Inductor Alternator

Abstract

The Guy-type Inductor alternator is a variable reluctance machine with slotted structures on both sides of the airgap; the complex airgap geometry and high frequency, tend to magnify distortions and losses to a greater degree than in normal machines. The existing theory of the Guy-type alternator is somewhat empirical and restricted; the lack of detail as to the actual flux distribution on open circuit and on load has led to the underestimation of losses. It is well known that the doubly-slotted structure is not covered by generalised machine theory suggesting that a different approach is needed for the analysis of Guy-machines. In this thesis a detailed study of flux distribution in the stator and rotor not only leads to a better understanding of the behaviour of the machine, but also allows the losses to be calculated with a greater degree of accuracy than previously achieved. Before commencing a study of flux distribution, it was necessary to have a good understanding of no-load permeance variations; detailed permeance calculations based upon a simple approximation were compared with Teledeltos plots and indicated the optimum tooth-slot parameters under open circuit conditions. A simple method based upon the airgap geometry and the physical movement of the rotor teeth across the stator surface, forms the basis of the theoretical work. Extension of the theory to include the effects of armature reaction and adding a series capacitor on load, leads to a method of calculating the flux distribution in the stator and rotor. The effects of damping and the calculation of field excitation on load is also discussed. A 3kHz experimental machine, heavily instrumented with search wires, was used throughout the work to verify the theory.