陳德玉臺灣大學:電機工程學研究所李政東Li, Cheng-DungCheng-DungLi2010-07-012018-07-062010-07-012018-07-062009U0001-1208200917010100http://ntur.lib.ntu.edu.tw//handle/246246/188119本論文主要在探討使用返馳式架構充的閃光燈充電電路。在現今的閃光燈充電電路中，常使用以下的控制模式：當二次側的電流逐漸減少到零的時候，功率開關將導通；而在一次側電流逐漸增加到一個固定的位準時，功率開關將關閉。篇論文使用等效電路來探討閃光燈電路在功率開關切換時所產生的振盪損耗現象的原由，並找出與振盪有關的因素。同時在本論文當中，提出了另一種讓功率開關延遲導通的控制方法來降低或消除這個振盪。最後，經由實體測試電路驗證此新控制架構。This thesis deals with a commonly-used flyback charger circuit for photoflashpplications. Recently control scheme for such a photoflash circuit has been popular. Inuch a scheme, the power switch is turned on at the instant of zero current detectionnd turned off at a specified peak current level. The focus of this thesis is to understandhe phenomenon of current ringing often encountered at the MOSFET turn on, whichurts the efficiency.he circuit operation will be analyzed by the use of converter equivalent circuits.arameters relevant to the ringing phenomenon will be pinpointed. And a scheme toelay the turn on of the MOSFET will be proposed to alleviate the ringing problem. Anxperimental bread board was built and tested.誌謝 ...................................................................................................................... I要 ..................................................................................................................... IIbstract ................................................................................................................... IIIable of Contents ............................................................................................................ IVist of Figures ................................................................................................................. VIist of Tables ................................................................................................................ VIIIhapter 1 Introduction .................................................................................................. 1.1 Background ................................................................................................. 1.2 Objectives .................................................................................................... 2.3 Thesis Organization ..................................................................................... 2hapter 2 Conventional Photoflash Circuits ................................................................. 4.1 Introduction of Photoflash Circuits ............................................................. 4.2 Flash Unit .................................................................................................... 5.2.1 Flashing Principle of Flash lamp ...................................................... 5.2.2 Flash Lamp Trigger Circuit .............................................................. 6.3 Charger Circuit ............................................................................................ 8.3.1 Operating Principle of Photoflash Circuits ....................................... 8.3.2 Capacitor Charger Circuit ............................................................... 10.3.3 Power Stage of the Photoflash Circuit ............................................. 11.4 Control Circuit ........................................................................................... 12.4.1 Control Strategy .............................................................................. 12.4.2 Power Control IC ............................................................................ 16hapter 3 Analysis of Turn-on Ringing Phenomenon of Conventional Chargerircuit ........................................................................................................ 18.1 Introduction ............................................................................................... 18.2 Realistic Device Models ............................................................................ 19.2.1 Transformer .................................................................................... 20.2.2 Power MOSFET ............................................................................. 20.2.3 Power Diode ................................................................................... 25.2.4 Complete Circuit Model ................................................................. 26.3 Analysis of the Simplified Equivalent Circuit .......................................... 27.3.1 Analysis of the Duration of MOSFET Turn-on .............................. 27.3.2 Analysis of the Duration of MOSFET Turn-off ............................. 32.4 Summary ................................................................................................... 35hapter 4 Proposed Scheme to Reduce Turn-on Ringing Phenomenon ..................... 38.1 Introduction ............................................................................................... 38.2 Analysis of Resonant Period ..................................................................... 38.3 Two Turn-on Methods ............................................................................... 45.3.1 Zero Vds Turn-on............................................................................. 45.3.2 Min. Vds Turn-on ............................................................................ 47.4 Control Block Diagram ............................................................................. 50.5 Issues of Implementation .......................................................................... 52.5.1 Negative Input Current ................................................................... 52.5.2 Effect of Propagation Delay ........................................................... 53.5.3 Max. toff control .............................................................................. 54.6 Breadboard Tests ....................................................................................... 56.6.1 Device Selection and Specifications .............................................. 56.6.2 Conventional Circuit ...................................................................... 57.6.3 New Scheme Circuit ....................................................................... 60.6.4 Efficiency Comparison ................................................................... 67.7 Summary ................................................................................................... 69hapter 5 Conclusions ................................................................................................ 71ppendix A — Equations Derivation ............................................................................. 72eferences ................................................................................................................... 803227446 bytesapplication/pdfen-US返馳式臨界模式photoflashflybackboundary modethesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/188119/1/ntu-98-R96921019-1.pdf