The aim of this paper is to present a new analytical model developed for open-circuit magnetic field calculation in U-shape interior permanent magnet (IPM) machine. The model is developed based on the 2-D subdomain-model approach by solving Poisson’s and Laplace’s equations. The comprehensive theoretical derivations of the final analytical equations for the magnetic flux density distribution in the air-gap and in the permanent magnets are explained in detail. We also provide the calculation algorithm in form of a flow diagram suitable for engineers to compute the radial and the tangential component of the magnetic flux density in all subdomains of slotless brushless machines with any possible number of rotor pole pairs of U-shaped IPMs. A slightly modified algorithm also applies to V-shaped IPMs.
COBISS.SI-ID: 12682068
The primary objective of the study was to improve the static torque characteristic of SynRM by appropriate selection of rotor geometry using design of experiments (DOE) by Taguchi optimization method. The preliminary finite element based numerical model of a SynRM was built and parametric analysis of rotor geometry was performed in order to investigate the impact of number of magnetic flux barriers and their position and size on the resulting static torque characteristic. The acquired characteristics were processed by Fourier analysis in order to identify the content of higher harmonics responsible for the machine torque ripple resulted by each rotor geometry. The processed results were used for smoothing the static torque characteristic of SynRM using DOE by Taguchi optimization method. The design of experiments optimization method by Taguchi was successfully used and implemented for the optimization of the SynRM rotor geometry in order to improve its static torque characteristic. Based on the obtained results the guidelines are proposed for smoothing the static torque characteristic by selecting the appropriate rotor geometry, which may in turn significantly contribute to the reduction of the torque ripple of SynRM.
COBISS.SI-ID: 11938900
The primary objective of this study was to investigate different stator configurations of switched reluctance motors (SRM) in order to mitigate electromagnetically excited audible noise and vibration. We analyzed natural frequencies of different SRM stator configurations by virtue of modal analysis theory. The three-dimensional numerical modeling of SRM stator geometry was performed by using finite element method. Based on the output results, we propose the solutions on how to select an appropriate stator configuration in order to increase its natural frequencies beyond the resonant operational frequency, and thus, to mitigate the resulting audible noise and vibration.
COBISS.SI-ID: 11924052
Slotless permanent magnet machines theoretically do not produce any cogging torque, provided the stator inner surface reluctance remains unchanged. However, a cogging torque may occur due to a change in the electromagnetic design following material cost reduction in the manufacturing process. When the electromagnetic design is changed to reduce the waste in the manufacturing process (stamping of the laminations) by dividing the stator toroidal ferromagnetic core into two equal parts, gluing them together introduces a very small non-magnetic gap between them, which affects the stored magnetic energy along the circumference and consequently gives rise to occurrence of a cogging torque. Using the finite element method its value is analyzed and verified by a laboratory measurement. Results of this work, will help scientists and engineers to understand the causes for the occurrence of the cogging torque in designing slotless permanent magnet machines, where the design itself is subjected to the manufacturing process.
COBISS.SI-ID: 23674371
Doubly-fed induction machine is usually used in variable-speed electric drives, where the rotor speed is in the vicinity of the synchronous speed. Finite-element-method model has been built and several studies, i. e. start up, sudden load change and fan drive, have been performed in order to verify the machine behaviour in supersynchronous motor operation. The simplest form of control (open-loop U/f control) has been used for rotor voltage supply, while the stator was connected directly to the public network.
COBISS.SI-ID: 12535636