Harmonička analiza frekvencijskog pretvarača s trofaznim diodnim mostom

master's thesis

• Title (english): Harmonic Analysis of a Frequency Converter with Three-Phase Diode Bridge Rectifier
• Author: Filip Hleb
• Mentor: Martina Kutija (mentor)
• Committee member: Martina Kutija (predsjednik povjerenstva)
• Committee member: Damir Sumina (član povjerenstva)
• Committee member: Marinko Kovačić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2019-09-18, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering

Abstract

U ovom radu analizirani su harmonici ulazne struje tri industrijska pretvarača u
laboratorijskim uvjetima, jednoga industrijskog pretvarača u industrijskim uvjetima i
sumirani strujni harmonici na sabirnici koje uzrokuju 4 grupe industrijskih pretvarača
u laboratorijskim uvjetima. Strujni harmonici analizirani su u realnim uvjetima i pri
promjenjivom opterećenju. Analizirani su karakteristični strujni harmonici, THDi, faktor
snage i valni oblici. Razmotreni su utjecaji istosmjerne i/ili izmjenične prigušnice
na harmonike ulazne struje. Zaključeno je da amplitude viših harmonika s porastom
snage dolaze u zasićenje, pa s porastom snage pada THDi i raste faktor snage. Dodatak
istosmjerne ili izmjenične prigušnice značajno smanjuje udio harmoničkih izobličenja
struje pretvarača. Naponska nesimetrija može uzrokovati pojavu struja tripleta. Kod
pretvarača koji su sumjerljivi snagom s napojnim transformatorom, transformator djeluje
kao izmjenična prigušnica. Kod sumiranja harmonika, zbog promjenjivog faznog
kuta, viši harmonici mogu se poništiti ili sumirati tako da je suma manja od algebarskog
zbroja pa je izobličenje struje sabirnice na koju je priključeno više pretvarača
manje od izobličenja struje jednog pretvarača sumjerljive snage.

Abstract (english)

In this thesis input current harmonics of three different industrial frequency converters
in laboratory conditions, one industrial frequency converter in industrial conditions
and summarized busbar current of 4 groups of industrial frequency converters in
laboratory conditions were analysed. Current harmonics were analysed in real conditions
and with varying the load. Characteristic current harmonics, THDi, power factor
and waveforms were analysed. The effects of DC choke and/or AC reactor on input
current harmonics were discussed. It is concluded that amplitudes of higher harmonics
get into saturation with an increase in load. This decreases THDi and increases
power factor. The addition of the DC choke or AC reactor significantly decreases the
harmonic distortion of input current. Voltage asymmetry can result in triplen current
harmonics flow. For converters that are comparable in power with its feeding voltage
transformers, the transformer acts as an AC choke. In harmonic summation, due to
the varying current phase angles, higher harmonics can cancel each other or sum in a
way that the resulting sum is less than algebraic sum of individual components. The
resulting distortion of busbar current is less when more converters are connected in
comparison to one of the comparable power.

• Keywords: Frekvencijski pretvarač; strujni harmonici; harmonička izobličenja; sumacija harmonika; trofazni diodni ispravljač; faktor snage; THD
• Keywords (english): Frequency converter; current harmonics; harmonic distortion; harmonic summation; three-phase diode rectifier; power factor; THD
• Language: croatian
• URN:NBN: urn:nbn:hr:168:103181
• Study programme: Title: Electrical Engineering and Information Technology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka elektrotehnike i informacijske tehnologije (magistar/magistra inženjer/inženjerka elektrotehnike i informacijske tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2020-01-07 18:26:27