Influence of saturation and saliency on the inductance of a four-quadrant transducer prototype machine

An inductance determination method that can be based on both experiments and calculations is discussed in this paper. The inductances of a four-quadrant transducer (4QT) prototype machine were measured and calculated with the two-dimensional time-stepping finite-element method (FEM), and the measured and calculated results are in good agreement. It is found that the d- and q-axis inductances are different, and the inductances obtained from the phase and line voltage are also different for both the two machines of the 4QT prototype machine. Analysis shows that the differences are caused by the saliency and d-axis saturation. Although there is little saliency for the double rotor machine (DRM), the two kinds of the inductance differences of the DRM are more serious than that of the stator machine (SM). This is because of the higher level of the d-axis saturation of the DRM. The inductances obtained from the phase voltage at very low frequency are recommended as final results for both experiments and calculations.