Modelling and performance of a hybrid synchronous reluctance machine with adjustable X d / X q ratio

Abstract

Analytical and experimental studies of a hybridised synchronous reluctance machine with a variable Xd /Xq ratio characteristic is the subject of this study. The machine comprises a round rotor and a salient pole machine element that is mechanically coupled together and integrally wound. There are two sets of poly-phase windings in each stator. The windings of one of the sets are transposed between the two sections of the machine. Either set of the windings may be connected to the supply while the other feeds a balanced capacitance load. It is shown that by tuning of the capacitance load that the Xd /Xq ratio varies theoretically from zero to infinity at very good power factors. The machine characteristics were verified using the generalised two-axis theory and validated by experimentation. The experimental and analytical results obtained show good agreement. Saturation was investigated by using the variation of the d-axis inductance with machine loading. A set of rotor windings may be introduced for the purpose that the machine be self-starting and self-synchronising as a motor. The rotor field windings when fed with dc, will make the machine also capable of operation as a stand-alone salient-pole generator. For this purpose, it was shown that for a very high saliency ratio, reluctance power can be considerably higher than the excitation power.