Primerjava načinov za preprečitev integralskega pobega v PI regulatorju

Avsec, Oliver (author), Ambrožič, Vanja (mentor), Nemec, Mitja (comentor)

Kljub svoji preprostosti in razvoju računalništva ter digitalnega procesiranja, se v industrijskih aplikacijah močnostne elektronike in elektromotorskih sistemov izkaže kot najboljša izbira klasični proporcionalno-integralni (PI) regulator. Realizacija PI-regulatorjev na mikroračunalniških sistemih je zelo enostavna, delovanje pa hitro in robustno. Hitro delovanje je še posebej pomembno pri regulaciji elektromehanskih pretvornikov v realnem času, s časovnimi konstantami reda nekaj deset mikrosekund. Tudi PI-regulator ima omejitve, katerim je potrebno posvetiti posebno pozornost in ena izmed njih je integralski pobeg, ki lahko ključno vpliva na reguliranca in kvaliteto regulacije. V diplomski nalogi je preučen pojav integralskega pobega, predstavljenih več rešitev za preprečevanje pojava ter podrobneje primerjani dve najpogostejši rešitvi na primeru vodenja elektromotorja nato še vpliv časa vzorčenja na vodenja z diskretno izvedbo preprečevanja integralskega pobega. Teorija pojava integralskega pobega in njegovih rešitev temelji na obstoječi literaturi, primerjava najpogostejših rešitev (pogojno integriranje in metoda prilagodljivih stanj) je bila narejena na podlagi računalniške simulacije v programskem okolju Matlab/Simulink. Z regulatorjem, ki smo ga nastavili po nastavitvenih pravilih Ziegler – Nichols, smo vodili sistem, ki je bil vzbujan s skočno funkcijo. Na unipolarno omejenem sistemu sta obe metodi izboljšali vse preizkušene integralske cenilke v primerjavi z zgolj osnovnim regulatorjem med 2,1 % in 11,8 %. Podobni rezultati so vidni tudi pri bipolarno omejenem sistemu, kjer je regulator dalj časa v nasičenja kar se odraža na še večjih razlikah. Pri kaskadno reguliranem unipolarno omejenem sistemu so se vrednosti cenilk prav tako izboljšale, a nekoliko manj izrazito, med 1,1 % in 5,3 % odvisno od cenilke. Pri implementaciji AW na diskretnem sistemu se je izkazalo, da je najboljše razmerje med vzorčnim časom in najmanjšo časovno konstanto, ki jo še želimo upoštevati, vsaj 1:2 ali še bolje 1:10, kjer v primerjavi z zveznim regulatorjem vrednost cenilke povečamo od 2 do 3 %.

• Language: Slovenian
• Keywords: integintegralski pobeg, metoda prilagodljivih stanj, metoda pogojnega integriranja, diskretni regulator
• Work type: Bachelor thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2023
• PID: 20.500.12556/RUL-149966
• COBISS.SI-ID: 165145091
• Publication date in RUL: 12.09.2023

Secondary language

• Language: English
• Title: Comparison among anti-windup techniques for PI-controller

Abstract

Despite its simplicity and the development of computing and digital processing, the classical proportional-integral (PI) controller is the best choice in industrial power electronics and electric motor applications. Implementing PI controllers on microcomputer systems is very simple and the operation is fast and robust. Fast operation is particularly important for real-time control of electromechanical converters, with time constants on the order of tens of microseconds. The PI controller also has limitations that need special attention, one of which is the integral windup, which can have a crucial effect on the controller and the quality of the control. The thesis examines the phenomenon of integral runaway, presents several solutions to prevent the phenomenon, and compares in detail the two most common solutions using the example of electric motor control, and then the effect of sampling time on the control with discrete AW implementation. The theory of the integral runaway phenomenon and its solutions is based on the existing literature. The comparison of the most common solutions (conditional integration and back-calculation) based on a computer simulation in the Matlab/Simulink software environment. With the controller set according to the Ziegler - Nichols set-up rules, we ran a system excited by a step function. On the unipolar-limited system, both methods improved all the tested integral performance indices compared to the basic controller alone by between 2.1% and 11.8%. Similar results are also seen for the bipolar-limited system, where the controller is kept in saturation for a longer period of time, resulting in even larger differences. In the case of the cascade-regulated unipolar-limited system, the values of the indices also improved, but slightly less significantly, between 1.1% and 5.3% depending on the performance index. When implementing AW on a discrete system, the best ratio between the sample time and the minimum time constant that we still want to take into account turned out to be at least 1:2 or even better, 1:10, where we increase the value of the performance indices by 2 to 3% compared to a continuous controller.

• Keywords: integral windup, back-calculation, conditional integration, discrete controller