US 12,132,397 B2
Power transformer for minimum noise injection in between primary and secondary winding “rompower active shield”
Ionel Jitaru, Tucson, AZ (US); Mihai Bogdan Jitariu, Neamt (RO); and Andrei Stefan Savu, Buchare (RO)
Filed by Rompower Technology Holdings, LLC, Milford, DE (US)
Filed on Jun. 21, 2022, as Appl. No. 17/845,963.
Application 17/845,963 is a continuation in part of application No. 16/732,240, filed on Dec. 31, 2019, granted, now 11,374,499.
Claims priority of provisional application 63/213,107, filed on Jun. 21, 2021.
Claims priority of provisional application 62/787,199, filed on Dec. 31, 2018.
Prior Publication US 2022/0320998 A1, Oct. 6, 2022
Int. Cl. H02M 1/44 (2007.01); H02M 3/335 (2006.01)
CPC H02M 1/44 (2013.01) [H02M 3/335 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A system for reducing common-mode noise, the system comprising:
a switch mode power supply including primary and secondary sides, primary and secondary side grounds, an input voltage source, a primary switch, a transformer having a magnetic core, and a power output, wherein the primary side and the secondary side each have at least a quiet termination wherein a voltage does not change with respect to the primary side ground and with respect to the secondary side ground;
the transformer includes a primary winding on the primary side connected to the input voltage source via the primary switch, and a secondary winding on the secondary side connected to the power output via a rectifier means, wherein the secondary winding has a first section and a second section;
first and second partial active shields, wherein the first partial active shield overlaps the first section of the secondary winding, and the second partial active shield overlaps the second section of the secondary winding;
wherein the first partial active shield winding is placed between the primary winding and the first section of the secondary winding, and the second partial active shield is placed between the primary winding and the second section of the secondary winding, and each of the first and second partial active shield windings has two terminations, are wound in a same direction as the secondary winding;
wherein the first and second partial active shields and the secondary winding have a number of turns; and
one of the two terminations of the first and the second partial active shield windings is connected to a quiet termination on the primary side, so that the terminations of the secondary windings and the first and second active shield windings that are adjacent each other carry alternating voltages of a same polarity such that there is a displacement current flowing in between the first and second partial active shield and the secondary winding, so that a common mode current from the primary side ground to the secondary side ground is zero.