US 12,095,433 B2
Isolated type active EMI filter having no additional elements on power line
Jin Gook Kim, Ulsan (KR); Sang Yeong Jeong, Ulsan (KR); and Dong Il Shin, Ulsan (KR)
Assigned to UNIST (ULSAN NATIONAL INSTITUTE OF SCIENCE AND TECHNOLOGY), Ulsan (KR)
Filed by UNIST (ULSAN NATIONAL INSTITUTE OF SCIENCE AND TECHNOLOGY), Ulsan (KR)
Filed on Nov. 2, 2020, as Appl. No. 17/087,340.
Application 17/087,340 is a continuation in part of application No. PCT/KR2019/005268, filed on May 2, 2019.
Claims priority of application No. 10-2018-0050717 (KR), filed on May 2, 2018.
Prior Publication US 2021/0058070 A1, Feb. 25, 2021
Int. Cl. H03H 11/04 (2006.01); H01F 17/04 (2006.01); H01F 17/00 (2006.01)
CPC H03H 11/04 (2013.01) [H01F 17/04 (2013.01); H01F 2017/0093 (2013.01)] 9 Claims
OG exemplary drawing
 
1. An isolated type active electromagnetic interference (EMI) filter having no additional elements on a power line, the filter comprising:
a common-mode (CM) choke disposed on a power source side from which power is supplied, the CM choke having a form in which a winding is wound on each of a live line and a neutral line connected to an EMI source;
a Y-cap disposed on an EMI source side at which EMI occurs and including two capacitors connected in series, wherein the two capacitors are connected between the live line and the neutral line and are commonly connected to the ground;
a sensing winding wound on the CM choke and configured to sense a noise current of the CM choke;
an amplifier configured to amplify the noise current sensed by the sensing winding;
a transformer installed in front of the Y-cap, the transformer comprising a primary coil configured to receive a signal amplified by the amplifier and a secondary coil isolated from the power line by being connected to the ground connected to the Y-cap, the transformer configured to inject a signal of the secondary coil into the Y-cap as a compensation signal; and
a bypass branch configured to serve as a bypass to avoid resonance and disposed between the Y-cap and the transformer,
wherein the bypass branch comprises:
a first resistor (Rd1) comprising a first end connected to the Y-cap and a second end connected to the secondary coil of the transformer;
a capacitor (Cd) comprising a first end connected to the first end of the first resistor; and
a second resistor (Rd2) comprising a first end connected in series with the second end of the capacitor and a second end connected to the ground.