In this paper, a novel induction machine topology with wound, independently-controlled stator coils is presented. The introduced configuration of the stator-winding enables the individual energization and control of the coils in each stator slot. Therefore, the possibility of changing the number of poles and active phases in the stator winding during operation is explored in this study.

The rapid growth of offshore renewable energy projects has led to the increased usage of submarine cables, which are necessary for the power transmission to the mainland. In their majority, these are AC, three-core (3 C) armored power cables. The environmental impact of such cable installations has not been fully evaluated yet, although concerns have been raised about potential harmful consequences on the balance of natural ecosystems due to the emitted magnetic field. The armor existence and the twisted cable geometry make the magnetic field calculations in the vicinity of such cables more challenging than existing analytical methods which only consider straight or helically twisted conductors. Other, existing works account for the cable twisting effects when computing the field produced by AC, 3 C armored cables via numerical methods. A more accurate numerical method, accounting for the field-dependent magnetic permeability, is suggested in the present paper. The problem of magnetic field calculation around the cable is approached also analytically and a sufficiently accurate, faster solution is provided. Both methods are validated against experimental measurements, achieving an agreement better than that cited in the literature. Various design aspects, such as the conductor size, armor magnetic permeability and armor lay length, are also discussed.

Pole-phase changing induction machines (IMs) offer the capability to extend the torque-speed envelope compared to their fixed pole-phase counterparts. Dynamic pole-changing can achieve higher torque levels at lower speeds, utilizing higher pole numbers, and extended flux-weakening range with lower pole-number operations. This paper investigates the design impact on the optimum pole-phase changing behavior and respective split of the operating region to different pole-phase operations. Additionally, the improvement in terms of the overall torque per ampere capability and efficiency is illustrated. For the purposes of the analysis, two different IMs with wound independently-controlled stator coils (WICSC) and different original pole numbers are evaluated in an effort to quantify the extent of the benefits of pole-phase changing. These geometries correspond to machines that were originally designed with 2- and 6 magnetic poles, respectively. It is shown that, in the case of the original 2-pole WICSC machine, shifting to a higher pole number is notably beneficial in terms of efficiency in a significant part of the operating region, whereas in the original 6-pole, both higher and lower pole numbers significantly enhance the overall torque capability and efficiency. The results highlight the notable benefits of pole-phase changing IMs and offer deep insight towards the derivation of standard design guidelines for these machines.

In this paper, a test setup that emulates field conditions equivalent to the ones of the rotor of a Salient Pole Synchronous Machine (SPSM) is presented. A 3-D Finite Element Method (FEM) model of the test setup is used to examine the induced eddy currents and to estimate losses using direct eddy current calculation method. The high mesh resolution of the model enables an accurate calculation and detailed illustration of the induced eddy currents as well as the estimation of related losses via direct computation within the volume of the test samples. A comparison of the estimated eddy current losses is made for different lamination thicknesses and materials of the test object. In the paper it is shown that the approximation that the eddy current losses are directly proportional to the square of the lamination thickness is not valid in the considered cases.