Common-mode EMI filter with a separately wound ground winding
AssigneeAcuson Corporation
InventorJames B. Hutchison
Life of this patent
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Abstract
An EMI filter and method of manufacturing thereof is described. The filter includes two or more power conductors and a ground conductor. The power conductors and the ground conductor are separately wound onto a core to form a common-mode choke. The filter may be located in an equipment chassis. Capacitors may be coupled to the choke to improve filter performance. The core may comprise at least two magnetic beads. The core material and number of turns of the conductors may be chose to control the frequency range of common-mode noise rejection. The frequency range may be that in which adequate common-mode noise rejection is achieved for a diagnostic ultrasound machine, e.g., approximately 0 to 20 MHz.
Claims32
An EMI filter comprising:
- at least two power conductors, wherein each power conductor has an input for electrical coupling to a power outlet, and each power conductor has an output;
- a ground conductor;
- a core onto which the at least two power conductors and ground conductor are separately wound to form windings of a common-mode choke, when the windings of the ground conductor are circumferentially separated around the core from the windings of the at least two power conductors, the outputs of the power conductors for providing a power signal with reduced common-mode noise.
An EMI filter comprising:
- at least two power conductors;
- a ground conductor;
- a core onto which the at least two power conductors and the ground conductor are wound to form windings of a common-mode choke, wherein the core includes at least two magnetic materials of differing magnetic properties, and the windings of the ground conductor are circumferentially separated around the core from the windings of the at least two power conductors.
The filter of claim, 10 further comprising capacitors coupled to the choke to improve filter performance.
A method for manufacturing an EMI filter, comprising the steps of:
- providing a magnetic core;
- providing at least two power conductors, wherein each power conductor has an input for electrical coupling to a power outlet and each power conductor has an output;
- and
- winding at least two power conductors and a ground conductor separately onto the core to form windings of a common-mode choke, so that the windings of the ground conductor are circumferentially separated around the core from the windings of the at least two power conductors, the outputs of the power conductors for providing a power signal with reduced common-mode noise.
An EMI filter comprising:
- at least two power conductors;
- a ground conductor;
- a core onto which the at least two power conductors and the ground conductor are wound to form windings of a common-mode choke, wherein the core material and number of turns of the conductors are chosen to control the frequency range of common-mode noise rejection, and the windings of the ground conductor are circumferentially separated around the core from the windings of the at least two power conductors.
Dependencies are inferred from the claim text.