Active Suppression of Low-frequency Interference Currents by Implementation of the High-performance Control System for the Grid-interfaced Converters

Abstract

Original scientific paperOperation of traction drive and auxiliary power supply converters installed onboard modern vehicles causes increased content of line harmonics and interharmonic components in the line current. Passive techniques for filtration of low frequency interference line currents appeared to be insufficient, but are combined with active mitigation techniques. The paper describes and suggests active suppression methods based on proper design of the grid interface of the power converter and its corresponding control system. Interference currents, including those induced by the operation of onboard power converters can significantly influence the correct operation of telecommunication, train control systems and other railway signaling infrastructure along the tracks, having direct impact to the safety of the railway transport. Therefore, suppression of low-frequency interference line currents requires careful implementation of active/passive methods. For purpose of quality evaluation of performances of the grid interface of the traction drive converters and its corresponding control system in particular, a series of tests for assessment of the line current frequency spectrum, resulting from the operation of the converter in typical exploitation conditions, were performed. Tests were performed in laboratory conditions and on the vehicle, with satisfactory results.Key words: Active filter, Control system design, Interference currents suppression, Line-side converters for railway applicationsAktivno potiskivanje nisko-frekvencijskih struja smetnji u pojnoj mreži djelovanjem na upravljačko-regulacijsku strukturu mrežnog sučelja pretvarača. Široka primjena pretvarača glavnih i pomoćnih pogona, na suvremenim željezničkim vozilima, uzrokuje pojavu povećanog sadržaja neželjenih viših harmonika te meduharmonika u strujama pojne mreže. Pasivne tehnike filtriranja nisko-frekvencijskih struja smetnji pokazale su se nedostatnim, te se kombiniraju s aktivnim tehnikama. U radu su predložene aktivne metode potiskivanja zasnovane na odgovarajućem dizajnu mrežnog sučelja pretvarača glavnih i pomoćnih pogona i pripadne upravljačko-regulacijske strukture. Struje smetnji, pa tako i one nastale kao posljedica rada pretvarača glavnih i pomoćnih pogona instaliranih na vozilo, uzrokuju elektromagnetske smetnje koje mogu značajno utjecati na ispravan rad telekomunikacijske (TK) i signalno-sigurnosne (SS) infrastrukture uz prugu, a samim tim i na sigurnost željezničkog prometa. Stoga se potiskivanju nisko-frekvencijskih struja smetnji u pojnoj mreži treba pristupiti s posebnom pozornošću, koristeći pasivne/aktivne mjere. U svrhu ocjene kvalitete postignutih radnih karakteristika mrežnog sučelja pretvarača za napajanje glavnog pogona, u smislu potiskivanja struja smetnji, proveden ječitav niz pokusa mjerenja spektralnog sastava struja pojne mreže pod djelovanjem pretvarača u tipičnim uvjetima eksploatacije. Ispitivanja su provedena u laboratorijskim uvjetima, kao i na vozilu, uz zadovoljavajuće rezultate.Ključne riječi: aktivni...

Predictive torque control of induction motor with integrated DC‐link voltage optimisation

“…Controversial is the varying switching frequency of the inverter, which, on the one hand, can be less irritating for humans [8]. However, due to the absence of modulator, the transistor switching may produce frequencies that can be problematic, for instance, in the case of railway safety systems [9].…”