Analysis and synthesis of an inductive storage millisecond pulse forming network

Van der Merwe, Julian Barend (2001-12)

Dissertation (PhD) -- Stellenbosch University, 2001

Thesis

ENGLISH ABSTRACT: Millisecond pulse forming networks (PFNs) as applicable to electro-thermal chemical (ETC) loads fall into the <1 MJ energy bracket. The energy requirements of these loads require specialised power sources involving staged energy conversion. For the <1MJ energy bracket, capacitive storage systems are usually employed. However, these systems exhibit low volume energy density and for volume sensitive applications; alternatives need to be considered. Inductive storage supplies form a sub-group of the static supplies that have theoretically superior volume energy density characteristics. This thesis documents the execution of a project concerned with the volumeoptimisation of an inductive storage supply. The system is composed of a three stage energy conversion chain. A prime power source (low power) charges an intermediate storage (IS) which is characterised by its medium power delivery capabilities. Energy is then transferred from the IS to the storage inductor which is characterised by its high power delivery capabilities. When sufficiently charged, the energy is then transferred to the load. Where pulse forming is required, the inductor storage must necessarily be modular. Switching elements to control the energy flow are also required. Work performed at Soreq, Israel, is used as the starting point. A topology variation of the XRAM topology presented by Soreq, original to this thesis, is presented and all its functioning modes are analysed. An existing volume model is analysed and expanded to incorporate heretofore unmodelled yet non-negligible considerations. The volume model generalises the effect of system modularity, subsystem technologies and allows for the incorporation of practical construction issues into the design process. The aim is to develop a 500 kJ, 80 kA, 20 kV system with a volume not exceeding lm3. This volume must include the IS, storage inductor and full switch volume. The optimisation algorithm and system topology developed in this thesis is validated through the construction and testing of a 1.2 kA, 2.5 kV 4 module prototype. A potential full ratings system, composed of contemporary device technologies and exhibiting a volume of just over 0.8m3, is proposed.

AFRIKAANSE OPSOMMING: Millisekonde pulsvormingsnetwerke, soos toegepas op elektrotermies-chemiese laste, val in die <1 MJ energievlak. Die energievereistes van hierdie tipe las vereis gespesialiseerde kragbronne wat die gestoorde energie in verskillende stadiums aan die las beskikbaar stel. Tans word kapasitiewe stelsels gewoonlik vir toepassings wat minder as 1 MJ energie benodig gebruik. ‘n Nadeel van hierdie stelsels is egter hulle relatiewe lae energiedigtheid. Vir toepassings waar lae volume van belang is, moet altematiewe metodes ondersoek word. Pulskragbronne wat van ‘n induktiewe energiestoor gebruik maak vorm ‘n deel van die klas van statiese kragbronne met hoe energiedigtheid. Hierdie tesis handel oor die optimering, in terme van volume, van ‘n induktiewe pulskragbron. Die stelsel bestaan uit drie stadiums, wat die energie van een vorm na ‘n ander omskakel en sodoende die vorm van die puls wat aan die las gelewer word, beheer. A lae-drywing primere kragbron laai ‘n medium-dry wing intermediere energiestoor. Energie word dan van die intermediere energiestoor na ‘n hoe-drywing stoorinduktor oorgedra. Nadat die induktor volgelaai is, word die energie aan die las oorgedra. Indien pulsvorming benodig word, kan van ‘n modulere induktor gebruik gemaak word. Vaste-toestand skakelelemente word gebruik om die energievloei te beheer. Navorsing wat by Soreq, in Israel, uitgevoer is, word as die vertrekpunt vir die studie gebruik. ‘n Verandering aan die XRAM topologie word voorgestel en die werking daarvan word in detail geanaliseer. ‘n Bestaande volume model word ondersoek en uitgebrei om ‘n aantal nie-weglaatbare verskynsels in aanmerking te neem. Die nuwe volume model maak voorsiening vir modulariteit, die effek van substelseltegnologie en ‘n aantal praktiese oorwegings wat in die ontwerp van die stelsel ‘n rol speel. Die finale doel is om ‘n 500 kJ, 80 kA, 20 kV stelsel in ‘n volume van 1 m3 in te pas. Hierdie volume van 1 m3 moet die intermediere energiestoor, die stoorinduktor, asook die skakelaars, bevat. Die optimeringsalgoritme en stelseltopologie wat ontwikkel is, word eksperimenteel deur middel van ‘n 1.2 kA, 2.5 kV, 4 module prototipe geverifieer. Laastens word aangetoon hoe ‘n finale stelsel, gebaseer op huidige skakelaartegnologie, met ‘n totale volume van 0.8 m3 moontlik in die toekoms ontwikkel kan word.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/52091
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