基于场路耦合的反激变换器板级辐射研究

Research on board level radiation of flyback converter based on field circuit coupling

辐射干扰问题是制约电源产品高频化、小型化的因素之一。基于场路耦合的仿真思路,建立MOSFET的电磁场有限元模型和高频变压器的等效高频电路模型。结合从SIwave电磁仿真软件中提取的PCB网络参数,对一款5 W输出的反激变换器的板级辐射干扰进行联合仿真,并对比了两种高频变压器模型对远场仿真结果的影响。实验结果表明,在230 MHz以内的频段3 m远场仿真超标频点与实测吻合,验证了该仿真方法的正确性,且简化的变压器二电容模型具有更宽频带的适用性;所得到的近场电磁场分布表明MOSFET和变压器副边的整流二极管是主要的辐射源。

Radiation interference is one of the bottlenecks that restrict the high frequency and miniaturization of power products.Based on the simulation idea of field circuit coupling,the electromagnetic field finite element model of MOSFET and the equivalent high frequency circuit model of high frequency transformer are established.Combined with the PCB network parameters extracted from SIwave,the board level radiation interference of a 5 W output flyback converter is co-simulated,and the influence of two high frequency transformer models on the far-field simulation results is compared.The experimental results show that the simulation results of 3 m far-field within 230 MHz are in good agreement with the measured results,which verifies the correctness of the simulation method,and the simplified two capacitance model of transformer has wider applicability;the obtained near-field electromagnetic field distribution shows that MOSFET is the main source of electric field radiation,and the rectifier diode at the secondary side of transformer is the main source of magnetic field radiation.