The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 22, 2000
Filed:
Mar. 02, 1998
Tsuneo Kume, Arlington Heights, IL (US);
Mahesh M Swamy, Germantown, WI (US);
Yaskawa Electric America, Inc., Northbrook, IL (US);
Abstract
A noise attenuation circuit is used in a motor drive system. The motor drive system includes a variable frequency drive having a pulse width modulated inverter converting DC power from a DC bus to three-phase power output on three-phase conductors for driving a motor. The noise attenuation circuit comprises a common-mode transformer including a common mode choke having a core, with first, second and third choke windings on the core, each connected in series with one of the three phase conductors, and a fourth winding on the core. A three-phase iron core transformer creates a neutral point representing common mode voltage. The iron core transformer has three primary windings connected in a 'wye' configuration to the three phase conductors. The fourth winding has a start connected to the neutral point and an end operatively connected to the DC bus to force a current, dependent on the voltage of the neutral point relative to the DC bus, in the fourth winding of the common mode transformer in an opposite direction to cancel main common mode current.