Flyback converter for performing a zero voltage switch in boundary mode
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First Claim
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1. A flyback converter for performing a zero voltage switch in a boundary mode, comprising:
- a transformer including a primary winding and a secondary winding;
a series circuit including at least one auxiliary capacitor and a switch at the primary side in series connected with the auxiliary capacitor, the series circuit being in parallel connected with the primary winding;
a switch at the secondary side being in series connected with the secondary winding;
a main switch being in series connected with one terminal of the series circuit adjacent to the auxiliary capacitor; and
at least one driver circuit interconnected the main switch and the auxiliary capacitor for sensing voltage at a joining node of the main switch and the auxiliary capacitor, generating a driver signal, and sending the same to the switches at the primary and the secondary sides for switching them respectively;
wherein when the switch at the secondary side is turned into a closed condition, the switch at the primary side is switched to a closed condition enabling the switch at the primary side to store the electric energy of the primary winding to the auxiliary capacitor;
when the switch at the secondary side is turned from the closed condition into an opened condition, the closed condition of the switch at the primary side is maintained for a predetermined period of time enabling the auxiliary capacitor to charge the primary winding until the electric energy being charged into the transformer is sufficient to cause the main switch to perform a zero voltage switch.
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Abstract
The present invention is to provide a flyback converter by utilizing harmonic effect generated by a transformer thereof, after transferring electric energy in the transformer in a boundary mode, through cooperating with a simple control circuit to draw the charges stored in a main switch thereof out and enable the main switch to perform a zero voltage switch under a variety of loads in the boundary mode, which not only greatly reduces switch loss thereof, but also effectively limits an operating frequency of the main switch in a predetermined range to greatly decrease peak value of voltage caused by inductance leakage and have the advantages of high efficiency, high switching frequency and low noise without increasing the manufacturing cost.
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9 Claims
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1. A flyback converter for performing a zero voltage switch in a boundary mode, comprising:
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a transformer including a primary winding and a secondary winding; a series circuit including at least one auxiliary capacitor and a switch at the primary side in series connected with the auxiliary capacitor, the series circuit being in parallel connected with the primary winding; a switch at the secondary side being in series connected with the secondary winding; a main switch being in series connected with one terminal of the series circuit adjacent to the auxiliary capacitor; and at least one driver circuit interconnected the main switch and the auxiliary capacitor for sensing voltage at a joining node of the main switch and the auxiliary capacitor, generating a driver signal, and sending the same to the switches at the primary and the secondary sides for switching them respectively; wherein when the switch at the secondary side is turned into a closed condition, the switch at the primary side is switched to a closed condition enabling the switch at the primary side to store the electric energy of the primary winding to the auxiliary capacitor;
when the switch at the secondary side is turned from the closed condition into an opened condition, the closed condition of the switch at the primary side is maintained for a predetermined period of time enabling the auxiliary capacitor to charge the primary winding until the electric energy being charged into the transformer is sufficient to cause the main switch to perform a zero voltage switch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Litigation Data
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Current AssigneeSkynet Electronic Company Limited
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Original AssigneeSkynet Electronic Company Limited
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InventorsPai, Kun-Shan, Wang, Po-Chueh, Liang, Jim H., Huang, Kuo-Chien
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Primary Examiner(s)BERHANE, ADOLF D
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Application NumberUS10/824,471Publication NumberTime in Patent Office530 DaysField of Search363/16, 363/20, 363/21.01, 363/21.12US Class Current363/16CPC Class CodesH02M 3/33571 Half-bridge at primary side...
