Transformer saturation and unusual system oscillation in capacitively coupled half-bridge or full-bridge forward converters: causes, analyses, and cures
{"title":"Transformer saturation and unusual system oscillation in capacitively coupled half-bridge or full-bridge forward converters: causes, analyses, and cures","authors":"R. Redl, N. Sokal, C.W. Schaefer","doi":"10.1109/PESC.1988.18213","DOIUrl":null,"url":null,"abstract":"In capacitively coupled bridge converters, duty-ratio unbalanced can cause transformer saturation and resulting transistor destruction. Independently, modulation of the transistor storage time by variations of collector current can cause low-frequency system oscillation which leads also to transformer saturation, and additionally causes low-frequency conducted EMI which is difficult to filter. A resistor shunting the coupling capacitor is suggested as a simple but effective cure for both problems. Mathematical analyses for both phenomena, a design procedure for selecting the proper value of shunt resistance, and experimental results that confirm the analyses are presented.<<ETX>>","PeriodicalId":283605,"journal":{"name":"PESC '88 Record., 19th Annual IEEE Power Electronics Specialists Conference","volume":"17 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"1988-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"33","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"PESC '88 Record., 19th Annual IEEE Power Electronics Specialists Conference","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1109/PESC.1988.18213","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 33
Abstract
In capacitively coupled bridge converters, duty-ratio unbalanced can cause transformer saturation and resulting transistor destruction. Independently, modulation of the transistor storage time by variations of collector current can cause low-frequency system oscillation which leads also to transformer saturation, and additionally causes low-frequency conducted EMI which is difficult to filter. A resistor shunting the coupling capacitor is suggested as a simple but effective cure for both problems. Mathematical analyses for both phenomena, a design procedure for selecting the proper value of shunt resistance, and experimental results that confirm the analyses are presented.<>