مبدل‌هاي دوجهته كليدزني نرم غيرايزوله بسيار افزاينده/ بسياركاهنده با تعداد عنصرهاي كاهش يافته براساس سلف هاي تزويجي

چكيده انگليسي :

High step up down non isolated soft switching bidirectional converters with reduced elements based on coupled inductors Mohsen Packnezhad 19 January 2021 Department of Electrical and Computer Engineering Isfahan University of Technology 84156 83111 Isfahan IranAbstractKey WordsHigh step up downs bidirectional dc dc converter Coupled inductor soft switching techniques zero voltage switching ZVS zero current switching ZCS Pulsating current IntroductionRecently the demand for fossil fuel resources are confined due to the environmental issueswhich has led to the utilization of renewable energies such as solar and wind energy Inrenewable energy systems the storage devices such as batteries and ultra capacitors areessential due to the power difference between the source and the load The low voltage levelof storage elements can be remedied by series connection of storage devices but this createsmany other challenges which increases the cost and complexity Bidirectional converters withhigh voltage conversion ratio are proper solution for interface between the storage devices andthe DC bus Moreover the bidirectional dc dc converters are capable of reversing the direction m packnezhad@ec iut ac ir Supervisor Dr Hosein Farzanehfard hosein@iut ac ir Advisor Dr Ehsan Adib ECE Graduate Program Coordinator Dr Behzad Nazari Department of Computer Electrical Engineering Isfahan University of Technology Isfahan IranThe demand for renewable energy sources such as solar and fuel cells are growing due to less pollution comparedto fossil fuels These systems often require storage devices and a bidirectional dc dc converter BDC The BCDscommonly utilize to manage energy and convert voltage level between the dc bus and the storage devices It iscommon that the storage device voltage level low voltage side VL ranges from 12 to 48 V while the dc bus high voltage side VH is in 380 800 V to connect to an inverter Hence the voltage level difference between VHand VL is rather high By series connection of storage devices the low side voltage level can be increased butthis leads to many problems such as higher cost and shorter life of batteries The isolated BDCs can achieve ahigh step up step down voltage gain via the transformer turns ratio These converters are suitable for high powerlevels However in low to medium power applications where electric isolation between low and high voltagesides is not essential such as photovoltaic electric vehicles and power factor correction applications thenonisolated BDCs are more attractive due to fewer switches lower weight and cost Among nonisolated BDCs the buck boost converter is the simplest approach in order to have minimum devices low cost and complexity In the high voltage conversion ratio applications the duty cycle reaches near unity in the boost operating stateand extremely low in the buck operating state which causes high current stress reverse recovery problem andconduction losses Therefore a BDC with a high step up step down voltage conversion ratio should be utilizedfor these applications Appling coupled inductors to buck boost bidirectional converter is the most effective wayto achieve high voltage conversion ratio and overcome the mentioned problems These converters have fewerelements and smaller leakage inductance as compared to the isolated bidirectional converters In this dissertation the coupled inductors technique is applied to buck boost converter to extend the voltage conversion ratio and toovercome the associated problems

پاك نژاد،‌ محسن

مبدل‌هاي دوجهته كليدزني نرم غيرايزوله بسيار افزاينده/ بسياركاهنده با تعداد عنصرهاي كاهش يافته براساس سلف هاي تزويجي

مبدل‌هاي دو جهته بسيار افزاينده/كاهنده , سلف‌هاي تزويج شده , كليدزني نرم , كليدزني تحت ولتاژ صفر , كليدزني تحت جريان صفر , جريان پالسي