【摘要】 准谐振(QR)开关电源应用谐振原理实现开关管零电压导通,从而减小开关损耗。由于电路工作在临界导通模式,电源工作频率会随输入电压及负载的变化而变化,给设计工作造成一些困难。为确定变换器的工作频率,首先从准谐振零电压反激式软开关电源的原理入手,分析了开关周期中开关管漏、源级电压的变化,建立了各阶段时间与电路参数之间的关系,得到了开关电源工作频率的计算公式。最后,基于L6565设计实际电路并进行了验证。研究结果为进一步进行优化设计奠定了基础。更多还原

【Abstract】 Quasi-resonant(QR) switching power supply achieve the breakover of switching tube at zero voltage by using the theory of resonant.So it can reduce the loss at switching.Because the circult is working at critical conduction mode,the frequency of this switching power supply is changed with the input voltage and output load,which brings some trouble for design.In order to certain the optimum working frequency,the theory of QR zero voltage switching(ZVS) flyback was investigated.After analyzing the change of voltage on switch,the relation between the circuit parameter and time in different periods was established.And the formula for calculating the optimum working frequency was deduced.Finally,the experiment based on L6565 was tested.The experimental results show that the analysis lays the foundation for the futher more optimization.更多还原