Noise Source Equivalent Circuit Model for Off-Line Converters and its use in Input Filter Design

As a s t e p toward d e s ig n in g a f am ily o f power l i n e i n t e r f e r e n c e f i l t e r s d e d i c a t e d f o r o f f l i n e sw i t c h in g mode power s u p p l i e s , an e q u i v a l e n t c i r ­ c u i t was developed t o d e s c r i b e t h e t y p i c a l c h a r ­ a c t e r i s t i c s of t h e n o i s e source e x i s t i n g a t th e AC t e r m i n a l s of t h e s e s u p p l i e s . The model uses l i n e a r e l em en ts t o p r e d i c t t o a f i r s t o rd e r th e behav io r o f RFI f i l t e r s as a p p l i e d t o sw i t c h in g mode power s u p p l i e s . C o n s o l i d a t i n g b a s i c f i l t e r and matching c i r c u i t a n a l y s i s with t h e e q u i v a l e n t n o i s e s ou rce c i r c u i t f a c i l i t a t e s t h e development o f an optimum RFI f i l t e r f o r sw i t ch in g mode power s u p p l i e s .