返馳式轉換器內二次側定電壓定電流輸出低待機功率損耗的控制電路設計

Abstract

在隔離型電源轉換器中，返馳式轉換器由於具有電路架構簡單、低成本和較少的元件數目之特性，因此廣泛地使用在低功率電子產品上。然而在傳統架構中，當待機時二次側的控制晶片會使光耦合器上流過一大電流，來維持輸出的穩定。然而直觀上來說，待機時的功率消耗應該是最低的，因此透過將系統回授電路的相位反轉180度，藉此來降低電流量，達到有效的減少待機功率損耗，且保有原先二次側控制晶片內的定電壓定電流輸出的控制。 透過參考市面上晶片的參數，經由計算將新系統參數調整與其相當，最後再經過模擬來證明實際減少待機損耗。

In all of isolated power converters, flyback converters are widely used for low power electrical appliances because of its simple circuit topology, low cost and fewer components. But in traditional structure, for acquiring the stable output secondary-side control IC sinks big current through photocoupler when no loads. However, standby power loss shall be the lowest intuitively. Therefore, reverse phase 180 degrees of the feedback topology in the system for reducing this current. To achieve cutting down the standby power consuming efficiently and it keeps the function, constant voltage and constant current control, original secondary-side control IC had. Through taking parameters of the common IC on the market for reference, adjust the parameters in new system by calculating about the same. Finally, prove that the way proposed efficiently reduces the standby power loss by simulation.