基于基波纹波比的大功率本安Buck变换器的设计

针对具有电感、电容(LC)滤波的本安Buck变换器输出纹波电压难以精确计算的问题,提出一种可快速、准确计算其输出纹波电压大小的方法。通过构建该变换器在电感电流连续模式下的等效电路模型,分析其频率特性,得出了该变换器的输出稳态响应。进一步的纹波理论计算及仿真分析表明可用基波电压纹波比近似全纹波比来求解该变换器输出纹波电压的结论。同时,为了给设计者提供理论指导,得出了满足输出纹波电压指标要求的电感、电容参数设计方法。与典型Buck变换器参数对比,发现在同样的电气性能指标要求下,采用LC滤波的Buck变换器仅需很小的电感、电容。表明该变换器更容易满足本安性能要求。最后,通过实验样机验证了输出纹波电压计算方法的准确性及元件参数设计思路的可行性。

Design Methods of High Power Intrinsically Safe Buck Converter Based on the Fundamental Ripple Ratio

Aiming at the problem that the output voltage ripple (OVR) of the intrinsically safe Buck converter with LC filter is difficult to calculate accurately, a method to calculate the OVR quickly and accurately is proposed. By constructing the equivalent circuit model of the converter in continuous conduction mode (CCM), the frequency characteristic of the converter is analyzed, and the output steady-state response of the converter is obtained. Further ripple theory calculation and simulation analysis show that the fundamental ripple ratio can be used to approximate the full ripple ratio to solve the OVR of the converter. At the same time, in order to provide theoretical guidance to the designer, the design method of inductor and capacitor parameters that meet the requirement of OVR index is obtained. Compared with the parameters of typical Buck converter, it is found that the Buck converter with LC filter requires only a small inductance and capacitance under the same electrical performance. It shows that the Buck converter with LC filter is easier to meet the intrinsic safety performance requirement. Finally, the accuracy of the OVR calculation method and the feasibility of the component parameter design idea are verified by the experimental prototype.