This work deals with the differential evolution (DE) based method for simultaneous identification of the electric, magnetic and mechanical subsystem parameters of a line-start interior permanent magnet synchronous motor (LSIPMSM). The parameters are determined in the optimization procedure using the dynamic model of the LSIPMSM, the time behavior of voltages, currents and speed measured on the tested LSIPMSM, and the DE which is applied as the optimization tool. During the optimization procedure the DE changes the parameters of the LSIPMSM dynamic model in such a way that the differences between the measured and calculated time behavior of individual state variables is minimized. The paper focuses on the objective function definition, constraints settings for individual parameters, normalization of parameters, and above all the test and measurement procedures performed on the LSIPMSM, which all together make possible to determine the LSIPMSM dynamic model parameters valid for a broad range of operation, and thus, ensuring proper evaluation of the LSIPMSM%s line-starting capability. Some of the LSIPMSM parameters that can be determined by finite element analysis and experimental methods are compared to the values obtained by the DE, thus validating the DE based approach.
COBISS.SI-ID: 17638166
Magnetic particles with a controlled Curie temperature were prepared by reducing a Ni,Cu-hydrazine complex that was synthesized in a compartmentalizedstate of reverse micelles. The planned Curie temperature of 43 °C was achieved by a thermally activated homogenization of as-prepared alloy particles embedded in a NaCl salt environment. The particles were superparamagnetic with a blocking temperature of 16.5 K and a room-temperaturemagnetization of 2.5 emu/g. The particles exhibited a therapeutic Curie temperature that is suitable for self-regulating magnetic hyperthermia.
COBISS.SI-ID: 16893718
In this paper, the results of an experimental study and finite-element method (FEM) of the impulse characteristics of simply built practical earthing systems consisting of 2, 3, and 4 rods are reported. These electrodes are installed at three outdoor test sites having nonuniform soil and different soil profiles to provide variation in the result analysis. The tests on these electrodes were intended to determine the nonlinear characteristics of earthing systems which can be seen from their voltage and current traces and reduction of their impulse resistance values. Two-rod electrodes in the highest soil resistivity profile showed the largest reductions in impulse resistance due to soil ionization compared with other earth electrodes. Computer simulations of all the nine earthing systems using the FEM are also conducted, which showed good agreement with the measured results. It was also found from FEM that threshold electric field Ec is dependent on the earthing systems configurations, soil profile, and impulse resistances.
COBISS.SI-ID: 17282070
Motors in semi-hermetic compressor drives are mostly fed from line. Because of good cooling conditions, the motors are heavily loaded, and employ a specific rotor structure with ''C'' bore. In the field of semi-hermetic drives the use of induction motors (IMs) is still dominant, although different motor types with line-starting capabilities, as for example linestart interior permanent magnet synchronous motors (LSIPMSMs), can be used. This work presents the direct performance comparison of a family of commercially available three-phase four-pole IMs for semi-hermetic compressor drives with the equal size prototypes of LSIPMSMs. The motors were rated as 1, 2.5, 3.8, 5.5, 7.5 and 20 Hp. Presence of ''C'' bore in rotor structure can degrade LSIPMSM steady-state performance, therefore the LSIPMSM designs steady-state performances are evaluated by FEA as well by the experimental method. The motorsʼ dynamic performance is experimentally evaluated as well. The ultimate goal of this study is to reveal the improvement of LSIPMSMs characteristics in comparison to IMs characteristics and to check the possibility for the immediate replacement of existent IMs with LSIPMSMs in the target semi-hermetic compressor application.
COBISS.SI-ID: 72594433
This paper presents the Extended Lindstedt-Poincare (EL-P) method with multiple time scales to treat nonstationary vibrations of the electromechanical system, which are forced by a nonideal energy source. The subject of research are two electromechanical systems consisting from rotor system with rotating disc mounted on an elastic shaft and a system with a rotating eccentric mass coupled by a nonlinear shock absorber, which are driven by a D.C. motor as a nonideal energy source. By using extended Hamilton principle, governing nonlinear differential equations of the system are derived. By using multiple time scales, which correspond to the nonlinear frequencies of the system in addition to the slow time scale, which corresponds to the slowly varying parameter, the system of partial differential equations is obtained, which is successively solved by using the proposed EL-P method. The results of computation of the nonstationary vibrations in the passage through fundamental resonance in both systems are presented.
COBISS.SI-ID: 13234454