ABSTRACT

In order to improve the efficiency of high gain DC-DC converter using MOSFET as switching device, a novel zero-voltage soft-switching high gain DC-DC converter is presented. A main switch tube is used to replace the output diode in the conventional boost converter, and an auxiliary network is added to make the two switches realise true ZVS soft turn-on and all diodes realise true ZCS soft turn-off, which improves the efficiency and effectively suppresses the negative effect of diode reverse recovery. Furthermore, the output end of the converter is composed of three output capacitors in series, which avoids the converter working at the limit duty cycle, increases the voltage gain and reduces the switch voltage stress. Therefore, MOSFET with low voltage level and low on resistance can be selected as switching devices. The resonant capacitor and leakage inductance are used to reduce the current at the turn-off time of the switch. The operating principle and steady-state characteristics of the converter are analysed in detail. The design idea of the main parameters is given, and the efficiency and loss of the converter are evaluated. Finally, the experimental results on a 100 W prototype show that the efficiency reaches 95.79% at rated power.

摘要

为了提高以MOSFET为开关器件的高增益DC-DC转换器的效率，提出了一种新型的零电压软开关高增益DC-DC转换器。采用主开关管代替传统升压转换器的输出二极管，并增加辅助网络，使两个开关管实现真正的ZVS软开通，所有二极管实现真正的ZCS软关断，提高了效率有效抑制二极管反向恢复的负面影响。此外，转换器的输出端由三个输出电容串联组成，避免了转换器工作在极限占空比，提高了电压增益，降低了开关电压应力。因此，可选择低电压电平和低导通电阻的MOSFET作为开关器件。谐振电容和漏感用于降低开关关断时的电流。详细分析了变流器的工作原理和稳态特性。给出了主要参数的设计思路，并对转换器的效率和损耗进行了评估。最后，在 100 W 样机上的实验结果表明，在额定功率下效率达到 95.79%。