IS200VCRCH1BBC燃機卡件監(jiān)測PFC電感L2啟機電流如圖4,此時PFC電感電流被削頂，即PFC電流受到限制鉗位于13.1A，PFC電流波形良好，且B<0.32，實測通入13A電流時，電感感量為180uH（L2標稱電感量為190uH）,PFC電感未飽和L1差模電感參數(shù)為200uH/48Ts/0.7mm，實測其飽和電流如圖6，當通入13.1A電流（PFC啟動時被鉗位的電流）時感量只有為12.5uH,電感感量急劇下降，已經(jīng)出現(xiàn)了飽和現(xiàn)象。
IS200VCRCH1BBC燃機卡件此時π型濾波的電感L1已無法對PFC啟動過程中流過繼電器K1的電流進行有效濾波。更換差模電感L1，選用飽和電流更大的差模電感（飽和電流約16A/200uH），測試其觸點電流，導(dǎo)通瞬態(tài)電流8A，導(dǎo)通后電流尖峰最大17.4A，觸點電流尖峰明顯減小C1為π型濾波電路的第一個電容，輸入電壓直接對C1進行充電，會產(chǎn)生畸變脈沖充電電流。電容越大，畸變電流脈沖越大，從而導(dǎo)致繼電器的觸點電流峰值越大。在措施L1差模電感更換的基礎(chǔ)上減小C1容值由474/450V改為683/450V，測試繼電器觸點電流，發(fā)現(xiàn)繼電器觸點電流最大8.6A，電流尖峰明顯進一步減少（之前為17.4A）PFC控制IC啟動過程：大電解電容C8升壓過程中，PFC控制IC驅(qū)動輸出的占空比會由0升至最大Ton max，如圖10。PFC電流逐漸達到PFC電流采樣限制從而被鉗位如圖4。PFC啟機鉗位電流與PFC電流采樣電阻有關(guān)，實際工程設(shè)計中PFC電流采樣電阻R=22mΩ，PFC鉗位電流約13.1A。增大R=40mΩ，鉗位電流減小，沖擊電流尖峰減小，同時也可增大L1在啟機時的感量,增大PFC π型濾波效果，如圖11，觸點電流尖峰最大9.6A。PFC電流采樣電阻直接和產(chǎn)品的過流能力有關(guān)，一般情況下，過流點設(shè)計好后，不建議改動此電阻。
，輸入端繼電器閉合后出現(xiàn)較大沖擊電流可總結(jié)如下：PFC電流采樣電阻小即過流點大，PFC開始工作時（升壓）輸入電流達到鉗位點的電流大；π型濾波的差模電感如果出現(xiàn)飽和的情況，會失去對電流的抑制作用；濾波電容C1電容值越大，畸變電流脈沖越大。繼電器在開關(guān)電源產(chǎn)品上的設(shè)計參考
1）輸入端的π型濾波電路：選用飽和電流更大的差模電感，同時減小π型濾波第一個電容容值；
2）增大PFC電流采樣電阻，減小PFC鉗位電流。（這點要和產(chǎn)品需求的過流能力平衡）
除了從電路上對參數(shù)進行優(yōu)化外，繼電器的選型也很關(guān)鍵，這里介紹下繼電器觸點材料不同在應(yīng)用上的差異。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.
