基于谐振变换器的自适应窄频率范围变频与定频混合调制策略

Adaptive narrow frequency range variable⁃frequency and fixed⁃frequency hybrid modulation strategy based on resonant converter

近年来,谐振变换器因效率高、功率密度高、软开关范围宽等特性而被广泛应用于电动汽车、新能源发电、航空航天电源等领域。谐振变换器一般采用脉冲频率调制(PFM),在轻负载和宽输出场景下开关频率的变化范围过宽,存在无法实现软开关、变压器利用率低、电磁干扰严重等问题。为此,文中提出一种自适应窄频率范围变频与定频混合调制策略。该策略具有频率变化范围窄、自适应切换频率、全过程实现软开关的优点。首先阐述混合调制策略的工作原理、设计流程和性能分析,再通过一台串联谐振转换器(SRC)的实验平台对所提出的调制策略进行验证。

In recent years,resonant converters have been widely used in electric vehicles,new energy generation,and aerospace power supplies due to their high efficiency,high power density,and wide soft-switching range.Resonant converters generally use pulse frequency modulation(PFM),which has a wide range of switching frequency changes under light loads and wide output scenarios,resulting in problems such as inability to achieve soft switching,low transformer utilization,and severe electromagnetic interference.An adaptive narrow frequency range variable frequency and fixed frequency hybrid modulation strategy is proposed,which has the advantages of narrow frequency variation range,adaptive switching frequency,and full process to achieve soft switching.The working principle,design flow and performance analysis of the hybrid modulation strategy are described in this paper,and the proposed theory is verified by an experimental platform based on a series resonant converter(SRC).