US 6,982,881 B2
Current detecting circuit and power converter having the same
Shih-Hsien Chang, Taoyuan Hsien (Taiwan)
Assigned to Delta Electronics, Inc., Taoyuan Hsien (Taiwan)
Filed on Nov. 09, 2004, as Appl. No. 10/984,211.
Claims priority of application No. 93107108 A (TW), filed on Mar. 17, 2004.
Prior Publication US 2005/0207183 A1, Sep. 22, 2005
Int. Cl. H02M 3/335 (2006.01)
U.S. Cl. 363—17 17 Claims
OG exemplary drawing
 
1. A current detecting circuit for use in a power converter having a control circuit, a switching circuit, a transformer and an energy storage element, said current detecting circuit comprising:
a filter electrically connected to said energy storage element for receiving a voltage signal from said energy storage element and filtering said voltage signal to obtain an alternating voltage change value;
a rectifier electrically connected to said filter for rectifying said alternating voltage change value to obtain a half-sine wave voltage change value; and
a differentiator electrically connected to said rectifier and said control circuit for performing a differential operation on said half-sine wave voltage change value to obtain a current change value of said energy storage element, wherein said current change value is compared with a predetermined reference value stored in said control circuit so as to dynamically control the switching status of said switching circuit according to the comparing result.