Research on the parameters and performances of a 4QT prototype machine used for HEV

A four-quadrant transducer (4QT) is a hybrid electric vehicle (HEV) power train concept. In this paper, a 4QT prototype machine, which is integrated radially by two permanent-magnet synchronous machines [one stator machine (SM) and one double-rotor machine (DRM)], is investigated. The inductances of both the SM and the DRM are calculated with a phasor-diagram based 2-D finite-element method (FEM), which can include the effects of eddy current and saturation. The calculated results show that the effect of eddy current can be neglected for both the SM and DRM inductances, and the cross-magnetization influence on the SM inductances can be ignored but is remarkable on the DRM inductances. The magnetic coupling between the SM and the DRM is calculated with 2-D FEM, and it is found that little magnetic coupling exists, so the SM and the DRM can be controlled independently, which is a very good feature for HEV applications. With the effect of skewed slots considered, the torque and no-load line-to-line back electromotive force (BEMF) curves of the SM and the DRM are calculated with multislice 2-D time-stepping FEM. The average torques of the SM and the DRM both meet the requirements, and the torque ripples are quite low. The calculated and tested no-load line-to-line BEMF curves of the SM and the DRM are both in good agreements. Both the BEMF curves of the SM and the DRM are somewhat similar to sinusoidal ones, which proves a good design of the magnetic structure.