مبدل هاي اصلاح ضريب توان كاهنده تكفاز در سيستم الكتريكي هواپيماهاي تجاري

چكيده انگليسي :

Single Phase Step Down Power Factor Correction Converters in Electrical System of Commercial Aircrafts Mahdi Malekanehrad M malekanerad@ec iut ac ir September 22 2018Department of Electrical and Computer Engineering Isfahan University of Technology 84156 83111 Isfahan IranSupervisor Ehsan Adib E adib@cc iut ac irAbstractWith progress of power electronics domain in new generation aircrafts hydraulic and mechanical systems havereplaced with electrical systems By increasing the power consumption the importance of Power Factor Correction PFC subject in aircraft electrical system has increased and stringent standards such as DO 160D and ISO 1540have introduced on the power factor and harmonic currents of aircraft electrical system AC DC converters Boost converter with continuous input current high power factor and low EMI is the most commonly used front endPFC converter For driving the low voltage loads a second stage step down DC DC converter is used to decreasethe high output voltage of the boost converter The high output voltage of the boost converter increases theswitching losses and the voltage stress of the second stage switches and reduces the isolation transformer efficiencyand converter reliability Recently the use of the buck PFC converter instead of the boost converter in the front stage has been consideredwith the aim of reducing voltage stress of the elements reducing switching losses and increasing reliability But thepresence of dead angle in the input current of this converter decreases the power factor and increases input currentharmonics The aim of this study is to present buck PFC converters to reduce the input current dead angle and provide unitypower factor and low harmonic input current The proposed converters have bridgeless structures to reduceconduction losses and simultaneously have soft switching features to reduce switching losses In this study three new structures for the Buck PFC converter have been introduced In the first proposed converter a step down PFC converter with unity power factor and bridgeless structure operating in discontinuous conductionmode DCM has been presented In the positive half line cycle a buck converter and an auxiliary series flybackconverter are used to decrease the input current dead angle In the negative half line cycle a flyback converter hasused The element counts of this converter has reduced respect to same ones that provides a simple structure and lowcost By reducing the input bridge diodes only two semiconductor components are at the power path so theconduction losses of this structure have been decreased Then using the auxiliary circuit with passive components the soft switching feature has also been provided In the second proposed converter the method of using series auxiliary flyback converter is applied to two buckconverters so that the leakage inductance of the flyback converter is resolved and continuous conduction mode CCM of operation can be applied Then to simplify the second proposed converter structure the idea ofunidirectional switches is introduced so that the dead angle removing circuit can be applied for both half line cycles In the third proposed converter by using an auxiliary resonant circuit and its merging with the auxiliary flyback zero voltage switching of switches has been provided Also this converter has unity power factor and bridgelessstructure Keywords Single phase step down PFC converter aircraft electrical system bridgeless AC DC converter soft switching

ملكانه راد، مهدي

مبدل هاي اصلاح ضريب توان كاهنده تكفاز در سيستم الكتريكي هواپيماهاي تجاري

مبدل هاي PFC كاهنده تك فاز , سيستم توان هواپيما , مبدل هاي AC/DC بدون پل , كليد زني نرم