สำนักราชบัณฑิตยสภา

The Journal of the Royal Institute of Thailand Vol. 30 No. 4 Oct.-Dec. 2005 910 °“√ª√— ∫ª√ÿ ß «‘ µ™å À≈— °„π·À≈à ß®à “¬°”≈— ߉øøÑ “°√–· µ√ß ·∫∫„™â µ— «‡°Á ∫ª√–®ÿ ≈¥·√ߥ— π Abstract Improvement of Main Switches in the Switched-capacitor, DC Power Supply Mongkol Dejnakarintra Fellow of the Academy of Science, The Royal Institute, Thailand This article presents performance improvement of the main switches in the switched-capacitor, DC power supply described in a previously published article. The targets of improvement are the drive circuits of the two bipolar transistors used as the main switches. The old drive circuits use a gradually changing base current, whose waveform is similar to a half-sine wave, but the improved drive circuits use a jolting base current, whose waveform consists of a peaking pulse at the leading edge. This results in the collector current and the collector-emitter voltage overlapping in a shorter time, thus decreasing power dissipation in the transistors and increasing the efficiency of the whole power supply circuit. Another method for main switch improvement is achieved by replacing the bipolar transistors with MOSFETs and replacing the drive circuits for the base currents of the former with those for the gate-source voltages of the latter. Both methods give similar results, i.e., increasing the efficiency of the whole power supply circuit slightly, from 58% for the old circuit to 61% and 62.5%, respectively, for the two improved circuits. Key words : DC power supply, switch improvement, drive circuit. ¢Õß «‘ µ™å ´÷Ë ß°Á “¡“√∂𔉪„™â ª√–- ‚¬™πå „πß“πÕ‘ ‡≈Á °∑√Õπ‘ ° å °”≈— ßÕ¬à “ß Õ◊Ë π‰¥â °‘ µµ‘ °√√¡ª√–°“» ºŸâ π‘ æπ∏å ¢Õ¢Õ∫§ÿ ≥ π“¬Õ√√≥æ ≈‘È ¡ ’ ¡“√— µπå π‘ ‘ µÀ≈— ° Ÿ µ√ª√‘ ≠≠“‡Õ° Àâ Õߪؑ ∫— µ‘ °“√«‘ ®— ¬‰øøÑ “·√ß Ÿ ß ¿“§ «‘ ™“«‘ »«°√√¡‰øøÑ “ §≥–«‘ »«°√√¡- »“ µ√å ®ÿ Ó≈ß°√≥å ¡À“«‘ ∑¬“≈— ¬ ∑’Ë ‰¥â ™à «¬‡À≈◊ Õ„π°“√∫— π∑÷ °√Ÿ ª§≈◊Ë πª√‘ ¡“≥ ‰øøÑ “¢Õß«ß®√·À≈à ß®à “¬°”≈— ߉øøÑ “ „π∫∑§«“¡π’È ‡Õ° “√Õâ “ßÕ‘ ß [Ò] ¡ß§≈ ‡¥™π§√‘ π∑√å . ·À≈à ß®à “¬°”≈— ß°√–· µ√ß·∫∫„™â µ— «‡°Á ∫ª√–®ÿ „π°“√≈¥·√ߥ— π, «“√ “√√“™∫— ≥±‘ µ¬ ∂“π. °∑¡. : √“™- ∫— ≥±‘ µ¬ ∂“π; ªï ∑’Ë Ú˜ ©∫— ∫∑’Ë Û °.§.- °.¬. ÚıÙı, Àπâ “ ˜Ú˜-˜Û˜. [Ú] ¡ß§≈ ‡¥™π§√‘ π∑√å . °“√ª√— ∫ª√ÿ ß ¡√√∂π– ¢Õß·À≈à ß®à “¬°”≈— ß°√–· µ√ß·∫∫„™â µ— « ‡°Á ∫ª√–®ÿ ≈¥·√ߥ— π, «“√ “√√“™∫— ≥±‘ µ¬- ∂“π. °∑¡. : √“™∫— ≥±‘ µ¬ ∂“π; ªï ∑’Ë Ú¯ ©∫— ∫∑’Ë Ò ¡.§.-¡’ .§. ÚıÙˆ, Àπâ “ ÒÚı- ÒÛÒ. [Û] Pressman, A. I., Switching Power Supply Design, McGraw-Hill, N.Y., 1992, pp. 321-324. [Ù] Dejnakarintra, M., Y. Kulvitit, and G. Arya, Research and Development of Switched- mode Power Supplies, Technical Report prepared under Science and Technology Development Board, Ministry of Science, Technology and Energy, Project No. 493- 0340, Electrical Engineering Dept., Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand, 1990, p. 43.