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Magistrsko delo obravnava področje delovanja asinhronskega motorja. Asinhronskemu motorju je prigrajen frekvenčni pretvornik, ki omogoči nastavljanje vrtilne hitrosti in amplitudne vrednosti vhodne napetosti. Krmiljenje s skalarno V/Hz metodo je cenovno ugodnejše od vektorske, vendar pri tem prihaja do pretiranega magnetenja asinhronskega motorja, kar se še zlasti izrazi pri izkoristku ob nižjih obremenitvah. Namen naloge je doseči optimalno magnetenje motorja s pomočjo nastavljanja razmerja V/Hz pri različnih vrtilnih hitrostih in navorih motorja ter izboljšanje izkoristka električnega pogona z asinhronskim motorjem (EPAM). V programu Matlab smo razvili sistem numeričnih enačb, ki opisujejo delovanje asinhronskega motorja. Na podlagi rezultatov smo dobili vrednosti izgub in izkoristkov asinhronskega motorja in frekvenčnega pretvornika, ki smo jih primerjali z dobljenimi meritvami. V nadaljevanju smo izračunali izkoristke in letno porabo električne energije na primeru delovanja 2,2 kW sistema črpalke in EPAM. V zaključnem delu naloge smo za lažjo uporabo simulacij izdelali grafični vmesnik v oblikovalnem orodju App Designer. Z optimizacijo magnetenja asinhronskega motorja smo uspešno izboljšali izkoristke ter zmanjšali izgube asinhronskega motorja in EPAM, kar se je najbolj izrazilo pri nizkih obremenitvah. Največje zmanjšanje izgub se je pokazalo pri izgubah zaradi magnetenja ter pri statorskih izgubah v navitju. Iz dobljenih rezultatov z uporabljeno metodo magnetenja asinhronskega motorja je razvidno, da bi jih bilo smiselno uporabiti v industriji, kjer so obremenitve pogona nižje od nazivne vrednosti, saj bi tako zmanjšali izgube pogona ter obenem zmanjšali obratovalne stroške in podaljšali življenjsko dobo postroja. This master's thesis deals with the operation of an induction motor. The induction motor is equipped with a frequency converter, which enables the adjustment of the rotational speed and the amplitude of the input voltage. Control with the scalar V/Hz method is more cost-effective than vector control, but there is excessive magnetization of the induction motor, which is especially evident in the motor’s efficiency at lower loads. The purpose of the thesis is to achieve optimal motor magnetization by adjusting the V/Hz ratio at different rotational speeds and torques and to improve the efficiency of the electric drive with an induction motor (EDIM). In Matlab, we developed a system of numerical equations that describe the operation of an induction motor. Based on the results, we obtained the values of losses and efficiencies of the induction motor and the frequency converter, which we compared with the obtained measurements. Following this, we calculated the efficiencies and annual electricity consumption in the case of the operation of a 2.2 kW pump system and EDIM. In the final part of the thesis, we made a graphical interface in the design tool App Designer to facilitate the use of simulations. By optimizing the magnetization of the induction motor, we successfully improved the efficiencies and reduced the losses of the induction motor and EDIM, which was most pronounced at low loads. The largest reduction in losses was shown in magnetization losses and in stator losses in the windings. The results obtained using the magnetization method of an induction motor show that it would be sensible to use them in industry where drive loads are lower than the nominal value, as this would reduce drive losses and at the same time reduce operating costs and extend plant operating life. |
