针对低压输入的DC/DC变换应用,提出了一种定频脉冲宽度调制(pulse width modulation,PWM)的推挽正激谐振变换器.一次侧采用推挽正激结构,二次侧在谐振网络与倍压整流相结合的基础上引入两个有源开关,通过定频调节二次侧有源开关的占空比,变换器在一个开关周期内具备二倍压整流和四倍压整流两种模式,从而实现宽电压增益范围的调节.谐振网络的引入使一二次侧开关管均可实现零电压开通(zero voltage switch,ZVS).在分析工作原理的基础上,利用时域分析法推导得到了变换器的增益与重叠导通角的关系,并分析了开关管软开关的实现条件.搭建了额定功率1kW的实验样机,实验结果证明了原理分析的正确性与拓扑方案的可行性.
A Push-pull Forward Resonant Converter With Wide Input Based on Fixed Frequency Pulse Width Modulation
A push-pull forward resonant converter based on fixed frequency pulse width modulation(PWM)is proposed for low voltage input DC/DC conversion applications.The push-pull forward structure is adopted on the primary side,and two active switches are introduced on the secondary side based on the combination of a resonant network and a voltage-doubling rectifier.By adjusting the duty cycle of the secondary active switches at a fixed frequency,the converter has two modes of double voltage rectification and quadruple voltage rectification in one switching cycle,thereby achieving wide voltage gain range adjustment.With the introduction of a resonant network,zero voltage switching(ZVS)can be realized for both primary and secondary active switches.Based on the working principle analysis,the relationship between the gain of the converter and the overlapping conduction angle is deduced by using the time-domain analysis method,and the implementation condition of the soft switching of the active switches is analyzed.A 1kW experimental prototype is built,and the experimental results prove the principle analysis's correctness and the topology scheme's feasibility.
万方数据
维普
