中文摘要：

提出了一种谐振型推挽直流变换器拓扑，其输出电压是倍压电容平均电压的4倍，利用变压器漏感和倍压电容构成的LC谐振来传递能量。电路采用固定导通时间调节频率的控制策略，开关管和二极管可以实现零电流开关（ZCS）。详细分析了各工作模态，采用基波分析法建立了电压增益模型，推导了直流增益表达式．利用Matlab软件绘制了电压增益在不同频率比、漏感系数及品质因数下的曲线，并根据曲线设计了电路实验参数。最后，制作了一台20-28V输入／360V输出／额定功率400W的样机，实验波形及较高的变换效率验证了电路的正确性及所建立的增益模型的有效性。

英文摘要：

A resonant push-pull DC converter is proposed.The average voltage of the output is four times of the capacitance.The energy is transferred by the LC resonance between the vohage-doubled capacitances and the leakage inductors.The converter adopts fixed-conduction time and frequency-modulating method.All power switches and diodes can achieve zero current switching（ZCS）.Each operation modes are analyzed detailedly.The voltage gain model is bu- ilt with first harmonic analysis method and DC gain characteristic expression is deduced.Using Maflab to plot the curve of voltage gain under different frequency ratio, magnetizing inductance/leakage inductor ratio and quality factor. The circuit experimental parameters are designed based on the curve.At last,a 20-28 V input/ 360 V output/rated power 400 W converter is built and tested.The correctness of the circuit and the validity of the gain model are verified by the test waveforms and high efficiency.