IS200VCRCH1BBC燃机卡件监测PFC电感L2启机电流如图4,此时PFC电感电流被削顶，即PFC电流受到限制钳位于13.1A，PFC电流波形良好，且B<0.32，实测通入13A电流时，电感感量为180uH（L2标称电感量为190uH）,PFC电感未饱和L1差模电感参数为200uH/48Ts/0.7mm，实测其饱和电流如图6，当通入13.1A电流（PFC启动时被钳位的电流）时感量只有为12.5uH,电感感量急剧下降，已经出现了饱和现象。
IS200VCRCH1BBC燃机卡件此时π型滤波的电感L1已无法对PFC启动过程中流过继电器K1的电流进行有效滤波。更换差模电感L1，选用饱和电流更大的差模电感（饱和电流约16A/200uH），测试其触点电流，导通瞬态电流8A，导通后电流尖峰最大17.4A，触点电流尖峰明显减小C1为π型滤波电路的第一个电容，输入电压直接对C1进行充电，会产生畸变脉冲充电电流。电容越大，畸变电流脉冲越大，从而导致继电器的触点电流峰值越大。在措施L1差模电感更换的基础上减小C1容值由474/450V改为683/450V，测试继电器触点电流，发现继电器触点电流最大8.6A，电流尖峰明显进一步减少（之前为17.4A）PFC控制IC启动过程：大电解电容C8升压过程中，PFC控制IC驱动输出的占空比会由0升至最大Ton max，如图10。PFC电流逐渐达到PFC电流采样限制从而被钳位如图4。PFC启机钳位电流与PFC电流采样电阻有关，实际工程设计中PFC电流采样电阻R=22mΩ，PFC钳位电流约13.1A。增大R=40mΩ，钳位电流减小，冲击电流尖峰减小，同时也可增大L1在启机时的感量,增大PFC π型滤波效果，如图11，触点电流尖峰最大9.6A。PFC电流采样电阻直接和产品的过流能力有关，一般情况下，过流点设计好后，不建议改动此电阻。
，输入端继电器闭合后出现较大冲击电流可总结如下：PFC电流采样电阻小即过流点大，PFC开始工作时（升压）输入电流达到钳位点的电流大；π型滤波的差模电感如果出现饱和的情况，会失去对电流的抑制作用；滤波电容C1电容值越大，畸变电流脉冲越大。继电器在开关电源产品上的设计参考
1）输入端的π型滤波电路：选用饱和电流更大的差模电感，同时减小π型滤波第一个电容容值；
2）增大PFC电流采样电阻，减小PFC钳位电流。（这点要和产品需求的过流能力平衡）
除了从电路上对参数进行优化外，继电器的选型也很关键，这里介绍下继电器触点材料不同在应用上的差异。are susceptible to interference should not be too close to each other, and input and output components should be as far away as possible.
② There may be a high potential difference between some components or wires, so the distance between them should be increased to avoid accidental short circuit caused by discharge. Components with high voltage should be arranged in places that are not easy to touch during commissioning.
③ Components weighing more than 15 g should be fixed with brackets and then welded. Those large, heavy and heat generating components should not be installed on the printed board, but on the chassis bottom plate of the whole machine, and heat dissipation should be considered. The thermal element should be far away from the heating element.
④ For the layout of potentiometers, adjustable inductance coils, variable capacitors, microswitches and other adjustable components, the structural requirements of the whole machine should be considered. If it is adjusted in the machine, it should be placed on the printing board where it is convenient to adjust; If it is adjusted outside the machine, its position should be consistent with the position of the adjustment knob on the chassis panel.
⑤ Reserve the position occupied by the positioning hole of the printed board and the fixed support.
