双频DC-DC变换器的磁集成技术

Magnetic Integration of Double Frequency DC-DC Converter

双频Buck变换器由两个降压单元级联构成,具有动态响应快,开关损耗小等优势。然而不足的是磁件占据了整个系统的大部分体积与重量,降低了系统的功率密度。针对这一问题,提出一种三段式绕制磁集成技术,将磁件以解耦的方式集成在一副磁心中。该文首先建立集成磁件的磁路等效模型,通过抵消各绕组之间的耦合作用推导出解耦条件,并详细阐述了磁心的选取、匝数以及气隙的设计原则。其次,利用有限元仿真平台对所提集成磁件进行建模分析,与现有的集成方法相比,磁通密度分布更为均匀,磁心的利用率得到了有效提升。最后,搭建一台48 V/12 V、108 W的实验样机,体积和重量同分离磁件相比降低了31.2%和25.3%,提高了系统的功率密度,验证了该集成方法理论分析的正确性和可行性。

Miniaturization and high power density are the development trends in modern power electronic converters.However,the increase in high frequency inevitably leads to intensified switching losses,reduced converter efficiency,and increased electromagnetic interference.These factors,to some extent,limit the improvement of converter performance.In response to these challenges,various methods have been proposed to address the conflicting relationship between high frequency and efficiency.Soft switching technology,converter parallel technology,and double frequency converters have been utilized in power electronic converters to enhance system performance.Although these methods contribute to improvement,most of them involve the converter's magnetic components,leading to larger converter sizes and related environmental issues.To address these issues,this paper proposes a three-section winding integrated magnetic(TSWIM)technique based on a double frequency DC-DC converter.This technique decouples and integrates the magnetic components within one core of the converter.Through theoretical analysis,simulation,and experimental validation,it is demonstrated that this integration method achieves a uniformly distributed magnetic flux density within the magnetic core.Consequently,it reduces the volume and weight of the converter,while improving the power density of the system.Firstly,this paper establishes an equivalent magnetic circuit model for the TSWIM and deduces the decoupling condition by mitigating the coupling effect between each winding.To select a suitable core model,careful consideration is given to the magnetic saturation problem and window area dimensions.Mathematically deriving the maximum magnetic flux density generated by each magnetic column of the core from the TSWIM helps determine if the core's saturation magnetic flux density is reached.Finally,the number of turns in the integrated winding and the calculation method of the air gap are elaborated upon.Secondly,the working principle of the double frequency DC-DC converter under the integration is analyzed,and by constructing the gyrator-capacitor model of the TSWIM,the co-simulation method is utilized to verify that the integration method can enable the converter to operate normally.Then,the TSWIM is subjected to finite element simulation with the existing integration method(IM),and the results show that the TSWIM has a more uniform flux density distribution,smaller flux density,and smaller magnetic loss by comparing the flux density and magnetic core loss of the two.Finally,a 48 V/12 V,108 W experimental prototype was constructed to validate the TSWIM and compare it with the separated magnetic part(SM)as well as the IM.Based on the experimental findings,it can be concluded that both the IM and the TSWIM demonstrate a relatively similar response speed,approximately 2.85 ms,with respect to output voltage and dynamic response of high-frequency inductor current.In terms of low-frequency inductor current,the TSWIM and the SM mirror the fluctuations in high-frequency inductor current,exhibiting a response speed of around 3.2 ms.Consequently,the TSWIM and the SM remain nearly synchronized.Conversely,the IM exhibit a comparatively slower dynamic response speed.From the efficiency comparison,the efficiency of the TSWIM is closer to that of the SM,and the volume and weight are reduced by 31.2%and 25.3%compared with the SM,which improves the power density of the system,and the experiments and simulations verify the correctness of the theoretical analysis.