蓄电池充电电流控制的LLC谐振变换器研究

Research on LLC resonant converter for battery charge current control

LLC谐振变换器电压控制模式通常采用误差放大器输出电压来直接控制开关频率,该控制方法使LLC谐振变换器的增益与频率之间的关系较为复杂,导致补偿网络设计相对较难,动态响应速度较慢,且大多数控制方案都未考虑集成变压器次级漏感带来的虚拟增益对谐振变换器参数设计的影响。针对以上问题,研究了基于充电电流控制的LLC谐振变换器,分析了变压器次级漏感,推导出电压增益表达式。与传统电压模式控制LLC谐振变换器相比,充电电流控制LLC谐振变换器保持了软开关特性,输入瞬态响应速度和负载动态响应速度均有较大提升,无需压控振荡器,在简化反馈回路设计的同时实现了固有前路反馈。文中详细分析了充电电流控制LLC谐振变换器的工作原理和集成变压器次级漏感的考虑事项,最后通过仿真和实验验证了理论的正确性。

The voltage control mode of LLC resonant converter usually adopts the error amplifier output voltage to directly control the switching frequency.This control method makes the relationship between the gain and the frequency of the LLC resonant converter more complicated,which makes the compensation network design relatively difficult and the dynamic response speed is relatively slow,and most control schemes do not consider the effect of the virtual gain due to the secondary leakage inductance of the integrated transformer on the resonant converter parameter design.Aiming at the above problems,the LLC resonant converter based on charging current control is studied.The secondary leakage inductance of the transformer is analyzed and the voltage gain expression is derived.Compared with the traditional voltage mode control LLC resonant converter,the charge current control LLC resonant converter maintains the soft switching characteristics,as a result,the input transient response speed and load dynamic response speed are greatly improved.The voltage-controlled oscillator is not required,and the inherent front-end feedback is realized while simplifying the feedback loop design.In this paper,the working principle of the charging current control LLC resonant converter and the consideration of the secondary leakage inductance of the integrated transformer are analyzed in detail.Finally,the correctness of the theory is verified by simulation and experiment.