【作者】 郑敏；

【导师】 孙伟锋；

【作者基本信息】 东南大学 ， 微电子学与固体电子学， 2021， 硕士

【摘要】 随着电动汽车、数据中心、通信等领域的快速发展,对宽电压输入、高效率的DC-DC变换器的需求越来越大。Buck-Boost LLC级联变换器在高频小型化方面有着优秀的表现,但如何进一步提高变换器的宽输入范围和效率还有待研究。针对Buck-Boost LLC传统控制方法无法在宽输入电压下实现变换器功率管软开关的问题,首先分析确定了最优的中间母线电压,进一步建立了关于功率管占空比、相移范围的软开关边界模型,进而保证在最大和最小输入工况下变换器的软开关实现。为了提高Buck-Boost LLC级联变换器的效率,开展了以下三个方面的工作:(1)计算了级联变换器的电感匝数,并选择合适的磁芯。根据Dowell模型,确定了绕组的最佳铜厚。借助Maxwell对不同的绕组结构进行涡流场仿真,确定了合适的电感绕组的并联结构,减小电感的绕组损耗。(2)根据变压器匝比确定了磁动势最小的原副边绕组排列结构和最佳铜厚,减小变压器的绕组损耗。(3)通过简化相移P的计算表达式,提出最佳相移P控制策略,减小电感电流有效值,从而降低功率管损耗。基于以上研究,设计了输入电压范围250V-425V、输出24V/10A-50A的Buck-Boost LLC级联变换器样机。测试结果表明,变换器能在250V-425V输入电压范围内正常工作,同时原边功率管均实现了软开关,峰值效率达95.3%,达到设计指标要求。更多还原

【Abstract】 With the rapid development of electric vehicles,data centers,communications and other fields,there is an increasing demand for DC-DC converters with wide input voltage range and high efficiency.The BuckBoost LLC converter has excellent performance in high-frequency and miniaturization.But how to impove the input voltage range and efficiency should be studied.The soft-switching of switches cannot be realized with the traditional control method of BBLLC.To solve this problem,firstly,determined the best bus voltage of BBLLC.Secondly,the model of duty and phase is established to ensure that the soft-switching of switches can be realized with wide input voltage range.In order to improve the efficiency of BBLLC,there are three methods used.(1)Calculate the number of inductance turns,and select the appropritate magnetic core.Second,according to the Dowell model,the optimal copper thickness of the winding is determined.Finally,according to the eddy current field simulation of different winding structures in Maxwell,and the suitable parallel structure of inductance windings can be determined,which reduce the copper loss of inductor.(2)According to the turns radio of transform,the winding structure of transformer of the smallest magnetomotive force and the optimal copper thickness can be determined which can reduce the copper loss of transform.(3)By simplifying the calculation expression of the phase shift P,the optimal phase shift P control strategy is proposed.The strategy reduce the current effective value and the loss of switches.Based on the above analysis,a prototype of Buck-Boost LLC converter with input voltage range of250V-425 V and output of 24V/10A-50 A is built.The soft-switching of primary switches can be realized with input voltage range from 250 V to 425 V.The peak efficiency of the BBLLC can achieve 95.3%.更多还原