Elimination/reduction modulation technique for large industrial MV drives applications

Svi električni sustavi sa elektroničkim energetskim pretvaračima imaju problem pojave harmonika. Za rad industrijskih pogona takvi energetski pretvarači su neophodni te se nameće problem umanjenja štetnog djelovanja nelinearnih trošila na distributivnu mrežu. Pulsno-širinska modulacija je jedno od mogućih rješenja tog problema. Proračunom kutova sklapanja sklopki usmjerivača moguće je postići željeni valni oblik napona koji će umanjiti negativna djelovanja nelinearnih trošila na mrežu. Kutovi se proračunavaju Newton- Rapsonovom matematičkom metodom koja može biti pojednostavljena korištenjem računalnih programa poput MATLAB-a. Upravljanje radom usmjerivača vrši se pomoću zatvorene petlje koja kontrolira vrijednosti struja i napona u sinkrono rotirajućem dq sustavu. Predložen je model sustava za upravljanje koji upravlja amplitudom i fazom usmjerivača. Model je zatim predstavljen u softveru PLECS, te je njegova funkcionalnost potvrđena rezultatima simulacijeIn every electrical system with non-linear loads the problem of harmonics exists. For large industrial motor drives power electronics equipment is needed to operate them properly, so a solution on how to minimize the effects that they have on the utility network is highly needed. Selective Harmonics Elimination Pulse-width modulation (SHE PWM) represents one possible solution to the problem. By calculating switching angles for the Active Front End (AFE) rectifier it is possible to obtain a desired voltage wave form that will diminish some of the negative impacts nonlinear equipment cause to the supply network. Switching angles are calculated using the Newton-Rapson mathematical method which can be simplified by using a computer software program like MATLAB. To control the AFE a closed-loop control system that operates in a synchronous rotating dq frame is used. A model of the system that controls the amplitude and phase of the AFE voltage is suggested. The model is then presented in a software environment called PLECS, and its functionality is confirmed in the simulation results