基于NCP1207与UC3844的双管反激变换器比较

Comparison of Dual Switch Flyback DC/DC Converters based on NCP1207 and UC3844

高频、高效、高密度是目前电源技术的发展趋势。对基于NCP1207和UC3844的双管反激变换器的电路结构．工作原理及性能作了详细的比较，并进行实验验证。结果表明，基于NCP1207准谐振芯片的准谐振反激变换器利用开关管两端的电容与变压器初级的漏感产生谐振，并通过适当的控制实现了开关管在电压谷底开通，减小了开关损耗，提高了变换器的效率，比基于UC3844的反激变换器的效率高出2％-3％。

Now the development of the power supply trends to high frequency, high efficiency and high definition.The circuit structure,operation principle and performance of dual switch flyback DC/DC converters based on NCP1207 and UC3844 are compared and verified.The result proves that a novel flyback converter using quasi-resonant technology with NCP1207 is developed.When the converter operates in discontinuous conduction mode （DCM）,the switch can turn on at quasi-resonant valley by using the resonant between capacitor shunted to drain-source of switch and the leakage inductance of the transformer.The experimental results show that the efficiency of the converter based on NCP1207 can be two or three percents more than the converter based on UCC3844.