Wyniki 1-2 spośród 2 dla zapytania: authorDesc:"Konstantin KOVALEV"

High specific power HTS electric machines DOI:10.15199/48.2017.11.27

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One of the key parameters of electric propulsion system is the specific power. The development of all-electric aircraft requires the electrical machines with high specific power (20 kW/kg and more). Whereas conventional electrical machines possess the specific output power of 5 kW/kg without control and cooling systems [1], because they contain ferromagnetic core and copper windings. Thus, if we want to increase power of conventional electrical machine we need to increase its weight and size. The increasing of specific power of electrical machine is possible with the use of superconducting windings. Modern high temperature superconductors (HTS) have high transport current density - more than 500 A/mm2 [2]. This allows to increase electromagnetic loadings of the machine and increase its power. But development of such type of machine is very difficult scientific and engineering problem due to specific properties of modern HTS tapes. Besides HTS machines operate in extremely cold temperatures of liquid nitrogen (77K) and lower. Principal scheme of HTS machines Useful superconducting power devices, especially electric machines, have been developed, in particular for producing strong dc magnetic fields [3, 4, 12]. But such machines have only field HTS coils and copper armature coils and their specific power is not high enough for application at the aircraft. AC losses in superconductors have made it difficult to create practical and useful fully superconducting rotating machines. Thanks to improvement of properties of HTS wire AC windings in electrical machines can be made of them. Application of HTS field and armature coils will increase magnetic induction in the air gap and electric load of the stator. Both induction and electric load influences output power [5]. More than that fully HTS machine can be made without rotating cryostat. This construction element is very difficult to produce due to sealing problems. That is wh[...]

Methodic of calculation of fully HTS silent-pole electrical machine DOI:10.15199/48.2019.01.51

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High performance and specific power of HTS electrical machines make them the most promising in the way of develop of future electrical aircraft, high speed transport systems, wind turbines and etc [8, 9]. Design of HTS machine with HTS windings is the most interesting in case of high specific output parameters. In this paper fully HTS electrical machine with silent-pole rotor is described. Analytical expressions for the distribution of magnetic fields in the active zone of a fully HTS electrical machine. The design scheme of a multipolar salient-pole synchronous electrical machine with HTS windings on a magnetically soft rotor core is shown in Figure 1. In general, the stator winding can have different configurations and vary in the number of phases, slots, shortening, distribution, etc. To determine the analytical solution for the problem, the armature winding can be replaced by an equivalent current layer at the bore diameter. In particular, this approach was used in the studies of electrical machines with bulk HTS elements [1,2] and HTS windings [3, 4, 7]. Fig. 1. Design scheme of an electrical machine with a ferromagnetic rotor and HTS windings It is possible to use the superposition of the fields created by the currents in excitation and armature windings with the assumption of the constancy of relative magnetic permeability in ferromagnetic sections. The parameters of the machine under consideration are determined on the basis of approaches described earlier in [1, 4]. Therefore, in this paper obtained expressions take into account the relative magnetic permeability of HTS windings which can differ from [1], the magnetic properties of the salient-pole rotor can be taken into account only without saturation. The distribution of magnetic fields is described on the basis of Maxwell's equations with the following conditions on the boundaries of areas with different magnetic permeabilities [5]. To set the problem of cal[...]

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