Critical evaluation and application of position sensorless control techniques for reluctance synchronous machines

Villet, Wikus Theo (2014-04)

Thesis (PhD)--Stellenbosch University, 2014.

Thesis

ENGLISH ABSTRACT: The position sensorless controllability of the reluctance synchronous machine (RSM) is investigated in this thesis with the focus on industry applications where variable and dynamic torque is required from startup up to rated speed. Two low speed as well as one medium to high speed position sensorless control (PSC) method for RSMs are investigated. These methods are extended to operate in the entire rated speed region with a hybrid PSC structure that makes use of phase locked-loop synchronisation and a hysteresis changeover method. It is shown in this thesis that PSC of the lateral rib rotor RSM is not possible from zero up to ± 0.2 p.u current. It is shown through finite element (FE) simulations that PSC of the ideal rotor RSM however, is possible at zero reference current. A novel construction method is used to build two ideal rotor RSMs. Measured flux linkage curve results of the ideal rotor RSMs correlate well with simulation results and it is shown that the electrical angle of the machine can be tracked successfully at zero reference current. The FE simulation package is used to compare the saliency of the RSM on a per-unit scale to three types of field intensified permanent magnet (FI-PM) synchronous machines and a field weakening interior permanent magnet synchronous machine. It is shown that the saliency of the RSM is larger than that of the investigated PM machines from zero up to rated load. It is thus concluded that the RSM is well suited to saliency-based PSC (SB-PSC) methods, which are used to control synchronous machines at startup and low speeds. The hybrid PSC methods developed in this thesis, are tested and evaluated on three proposed industry applications. The first is a reluctance synchronous wind generator with an inverter output LC filter. The LC filter allows long cables to be used and reduces the voltage stress on the stator windings of the machine. The combination of the LC filter and hybrid PSC method allows the power electronics and controller to be stationed in the base of the turbine tower. A new stator quantity estimation method is derived to omit the need of current and voltage sensors on the machine side of the LC filter. Good maximum power point tracking laboratory results are shown with the high frequency injection-assisted hybrid PSC method. The second application investigated is a position sensorless controlled variable gear electric vehicle (EV) RSM drive. Simulation and measured results show good torque capabilities of the position sensorless controlled EV RSM. It is shown through simulation results that the fundamental current harmonic is dominant in the demodulation scheme of the high frequency injection position sensorless control (HFIPSC) method due to the high current rating of the proposed RSM. The HFI-PSC method is extended to reduce the effect of the fundamental current harmonic in the demodulation scheme without adding any additional filters. The final investigated application is a novel mine scraper winch, which uses two position sensorless controlled RSMs to retrieve ore from the blast site underground. The new design improves on the safety, efficiency and durability of the current scraper winch design. Measured results show that the position sensorless controlled winch RSM is able to deliver rated startup torque with both investigated SB-PSC methods. Finally an automation method is implemented and tested to limited the applied force on the scraper and automatically free itself when stuck.

AFRIKAANSE OPSOMMING: Die posisie sensorlose beheer eienskappe van die reluktansie sinchroonmasjien (RSM) word in hierdie tesis ondersoek met die fokus op industriële toepassings waar varierende dinamiese draaimoment vereis word vanaf stilstand tot by ken spoed. Twee lae spoed- en een ho¨e spoed posisie sensorlose beheer (PSB) metodes vir RSMe is ondersoek. Hierdie metodes is uitgebrei om twee hibriede PSB metodes to skep wat die RSM van stilstand tot by kenspoed posisie sensorloos kan beheer. Die ontwikkelde hibriede metodes maak gebruik van ’n histerese oorskakelings skema en fase geslote lus sinchronisasie Daar word in hierdie tesis bevestig dat die laterale rib RSM nie beheer kan word met die geondersoekte PSB metodes by nul stroom nie. Eindige element simulasie resultate wys egter daarop dat die ideale rotor RSM wel beheer kan word met die geondersoekte metodes by nul stroom. ’n Nuwe konstruksie metode is voorgestel om twee ideale rotor RSMe to bou. Gemete vloed omsluiting kurwes resultate korreleer baie goed met dié van die eindige element simulasies. Gemete resultate wys ook daarop dat PSB van die nuwe masjiene moontlik is by nul stroom. ’n Eindige element pakket is gebruik om die speek-koëffissiënt van die RSM te vergelyk met drie tipes veld-versterkte permanent magneet masjiene, asook een veld verswakte permanent magneet versinkte masjien. Die simulasie resultate wys dat die RSM se speek-koëffissiënt hoër is as die van die geondersoekte permanent magneet masjiene. Die RSM is dus geskik vir speek-koëffissiënt georienteerde PSB metodes, wat hoofsaaklik by stilstand en lae spoed gebruik word. Die ontwikkelde hibried PSB metodes is getoets en geëvalueer met drie voorgestelde industriële toepassings. Die eerste is ’n reluktansie sinchroon wind generator met ’n omsetter uittree laagdeurlaat filter. Die laagdeurlaat filter laat toe dat langer kabels vanaf die omsetter na die generator gebruik kan word. Die kombinasie van die laagdeurlaat filter en die PSB metodes laat toe dat die drywingselektronika en die beheerders in die toring basis geplaas kan word. Dit kan die gewig van die nasel verminder. Goeie maksimum drywingspunt volging laboratorium resultate word getoon met die hoë frekwensie ondersteunde hibried PSB metode. Die tweede geondersoekte toepassing is ’n posisie sensorlose beheerde, varierende ratkas elektriese voertuig RSM. Goeie simulasie en gemete draaimoment resultate van die RSM word getoon. Simulasie resultate toon dat die fundamentele q-as stroom harmoniek dominant is in die demodulasie skema van die hoë frekwensie PSB metode, as gevolg van die hoë ken stroom van die motor. Die hoë frekwensie PSB metode is uitgebrei om die fundamentele stroom harmoniek te onderdruk in die demodulasie skema sonder om enige filters by te voeg. Die finale toepassing is ’n nuwe myn windas wat van twee posisie sensorlose beheerde RSMe gebruik maak om klippe ondergronds te verplaas vanaf die ontploffings area. Die voorgestelde ontwerp verbeter die huidige ontwerp ten opsigte van die veiligheid, energie effektiwiteit en robuustheid. Gemete resultate wys dat ken draaimoment moontlik is met altwee speek-koëffissiënt metodes. ’n Automasie metode, wat die maksimum draaimoment op die windas beperk en automaties homself bevry indien hy vasval, is voorgestel en geëvalueer.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/86527
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