Chokes and Gapped Cores for SMPS and PFC

[fethiyeli]

Hi guys, i wanna ask u something about chokes or gapped cores. I will implement PFC circuit and SMPS but i dont know whether i need to use choke or gapped cores. I have read some books but they mention different things for this issue. Some of them just use ungapped cores while others dont for both PFC and SMPS. PFC is CCM boost type converter and SMPS is full-bridge converter. I just know that choke coils store enegry in their air gaps. I dont know whether these air gaps are needed in circuits like PFC and SMPS.

 

[pradeep.g.belchada]

For the choke u can use gapped or ungapped core it depends on the inductance. FOR SMPS AIR GAP IS NECESSARY

 

[fethiyeli]

For the choke u can use gapped or ungapped core it depends on the inductance. FOR SMPS AIR GAP IS NECESSARY

I have read something last night in book of Switching Mode Power Supply Design by Pressman. It says that if a ferrite core is used, then the core needs air gap in order to prevent saturation but if powder core is used, then air gap is not needed. Powder cores can be used up to 100kHz while the ferrite can be used more than 100kHz.

 

[pradeep.g.belchada]

saturation only occurs in smps transformer. as per the desgin considaration we have to set the inductance