有源箝位ZVS-PWM控制串联谐振变换器中提高同步整流效率的研究

Efficiency Improvement of Synchronous Rectification in ZVS-PWM Controlled Series-resonant Converter with Active Clamp

最近 ,带有同步整流电路的有效箝位ZVS-PWM控制串联谐振变换器研究和应用不断取得进展。不过 ,当输入电压偏离特定值时 ,其效率会严重下降。通过对其各种工作模态转换的分析 ,阐明了效率下降的原因。为解决这种效率下降 ,使用了带有分立电感和偶合电感的倍流型同步整流电路模型 ,并分析了他们的稳态特性。并且 ,通过实验 ,比较了中心抽头型和偶合电感型效率变化曲线。最后 ,通过分析和比较 ,得出结论 :提出的整流电路在一个较大输入电压范围内和低输出电压 ,大输出电流的负载条件 (3 3V ,5A)下 ,获得了 85 %的较高效率。

A ZVS-PWM controlled current-mode resonant converter previously propsoed includes an active-clamp circuit and a center-tap tpe synchronous rectifying circuit.This resonant converter has a high effictency for a specific input voltage.However,as the input voltage varies from the specifec value,the efficiency goes domn severely. This paper clarifies the cause of this efficiency drop through the atate transition analysis. To overcome the efficiency drop.we propose the usage of current-doubler type synchronous rectifying circuits with separate inductors and with a coupled inductor,and examine their steady-state characteristice. As a consequence, it is clarified that the propsoed redtifying circrits have achieved a high efficiency over 85% for a wide variation of input voltage under the load condition of 3.3V and 5A.