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Rast industrije električnih motora zahtjeva sve jeftinija i učinkovitija rješenja pa bi jedno od tih rješenja u budućnosti mogli biti i prekidačko-reluktantni motori. To je vrsta električnih motora s istaknutim polovima koji koriste promjenu reluktancije (magnetskog otpora) za stvaranje momenta i ono što ih izdvaja od ostalih motora je jednostavna građa i niska cijena.U prekidačko-reluktantnim motorima se napajaju namoti statora, a rotor nema namote te se može sastojati od jednog komada feromagnetskog materijala. To dosta pojednostavljuje mehanički dizajn, ali komplicira električni dizajn jer je potrebno napraviti neki sustav za izmjenu dovođenja napona u različite namote statora. U industriji, prijevozu, komercijalnim i stambenim primjenama dominiraju motori s permanentnim magnetima i asinkroni motori, ali prekidačko-reluktantni motori su pogodniji za rad pri visokim brzinama i temperaturama u usporedbi s ostalim tipovima motora zbog robusne rotorske jezgre koja može podnijeti velike brzine vrtnje, centrifugalne sile i visoke temperature. Mane prekidačko-reluktantnih motora su pulzacije momenta, akustična buka i vibracije te niski faktor snage pri radu s malim teretom. Pulzacije momenta i buka se mogu smanjiti promjenom različitih parametara kao što su geometrija statora i rotora, kombinacija polova, materijal, osovina te upravljanjem strujom. Opisom pretvorbe energije tijekom zakreta rotora objašnjeno je zašto prekidačko-reluktantni motor ima niski faktor snage pri radu s malim teretom i zašto je faktor snage viši u zasićenju. Prekidačko-reluktantni motori se identificiraju po broju polova statora i rotora, tako npr. prekidačko-reluktantni motor sa 6 polova statora i 4 pola rotora se skraćeno naziva 6/4 PRM. Izbor broja polova statora i rotora ima značajan utjecaj na rad i performanse motora, a utječe i na odabir broja faza i valovitost momenta. Opisano je modeliranje prekidačko-reluktantnog motora u programskom paketu Motor-CAD. Motor-CAD služi za elektromagnetsku i termalnu analizu i projektiranje električnih motora i ovdje je korišten na primjeru tri motora: PRM 12/8, PRM 24/16 i PRM 6/14.Promatraju se parametri prekidačko-reluktantnih motora u različitim radnim točkama te se prikazuju rezultati izračuna. Rad prekidačko-reluktantnih motora se može optimirati mijenjanjem struje, napona te kutova uključenja i isključenja. The growth of the electric motor industry requires cheaper and more efficient solutions, so one of these solutions in the future could be switched-reluctance motors. It is a type of electric motor with salient poles that uses a change in reluctance (magnetic resistance) to create torque and what sets them apart from other motors is its simple build and low cost. In switched reluctance motors, the stator windings are powered, and the rotor has no windings and can consist of one piece of ferromagnetic material. This greatly simplifies the mechanical design but complicates the electrical design because it is necessary to make a certain system to change the supply of voltage to the different stator windings. In industry, transport, commercial and residential applications, permanent magnet motors and induction motors dominate, but switched reluctance motors are more suitable for operation at high speeds and temperatures compared to other motor types due to a robust rotor core that can withstand high speeds, centrifugal forces and high temperatures. Disadvantages of switched reluctance motors are torque ripple, acoustic noise and vibrations, and low power factor when working with light loads. Torque ripple and noise can be reduced by changing various parameters such as stator and rotor geometry, pole combination, material, shaft and current control. The description of the energy conversion during rotor rotation explains why the switched reluctance motor has a low power factor when operating at light loads and why the power factor is higher in saturation. Switched reluctance motors are identified by the number of stator and rotor poles, so for example a switched reluctance motor with 6 stator poles and 4 rotor poles is called a 6/4 PRM. The choice of the number of stator and rotor poles has a significant impact on the operation and performance of the motor, affects torque ripple and the choice of the number of phases. The modelling of a switched reluctance motor in the Motor-CAD software package is described. Motor-CAD is used for electromagnetic and thermal analysis and design of electric motors and is used here on the example of three motors: 12/8 SRM, 24/16 SRM and 6/14 SRM. The parameters of the switched reluctance motors at different operating points are observed and the results of the calculation are displayed. The operation of switched reluctance motors can be optimized by changing current, voltage and on and off angles. |
