上谐振型并联谐振DC／DC变换器的分析与设计

系统地分析了高于谐振频率工作的并联谐振DC/DC变换器的工作原理，讨论了无损电容C1和C2以及MOSFET寄生二极管D1和D2对MOSFET零电压开关特性的影响。文中根据电路工作中电压和电流的相对关系，把谐振逆变器的工作状态分解成A，B两种工作模式，利用恒流模型和状态空间分析法导出电路的稳态解，研究了电路在稳态状态下状态变量初值I0和Uc0的确定方法和主要功率器件的工作区间长度，文中还给出了确定谐振变换器中MOSFET的平均电流^-Isw、电脉电流有效值Ir等主要参数额定值的表达式及其设计曲线。最后给出一个输出为160W/28V、谐振频率为100kHz和变换效率达89.9%的并联谐振变换器的设计实例和实验波形。

Analysis and Design of Parallel Resonant Converter Operating above Resonance

A systmatic analysis of the operating principles of a parallel resonant DC/DC converter operating above resonance is presented. It is discussed that the lossless capacitors C1 and C2 and parastic diodes D1 and D2 of MOSFETs have the influence on zero-voltage switching characters of MOSFETs. According to the relation between voltage and current in the circuit,the operating state of a resonant inverter is divided into two kinds of A and B models. The steady-state solution of the circuit is derived using constant current model and state space approach. The method of determining the initial values I0 and Uco under steady-state coditions and the operating interval of math parameters is studied. The design curves and the expressions for ratings of main parameters,such as the average currents Isw of MOSFETs and the r. m. s current Ir of the resonant inductor,are also presented in this paper. Finally,an actual design example of a 160W/28V parallel resonant DC/DC converter operating at 10DkHz with a conversion efficiency of 89. 9% and the experimental waves are given.