Universal Lighting Technologies, Inc.

Brandon Dyer

Donald Folker

Mike LeBlanc

Wei Xiong

John Jay Dernovsek

Travis L Berry

Stephen D Mays, Ii

Danny Pugh

Theodore E Kluska

A magnetic device for an electronic circuit includes a bobbin having a bobbin body with an axial passage, a first pin rail, and a second pin rail. A winding can be disposed around the bobbin body. A core can have a core leg extending into the axial passage. The bobbin can be disposed on a printed circuit board. The core and the winding can be elevated off of the printed circuit board. The bobbin can include a first spacing member positioned between the bobbin body and the first pin rail, and a second spacing member positioned between the bobbin body and the second pin rail. The core can be positioned on the first and second spacing members such that the core is at an offset position from the first and second bobbin pin rails. The winding can additionally be offset from the first and second pin rails.

Magnetic component with elevated bobbin

A common mode inductor includes a bobbin with two windings. A first winding is positioned between a first end flange and a first offset flange. A second winding is positioned between a second end flange and a second offset flange. The windings are spaced apart by a center section without windings. A pair of E-cores, each having a pair of outer legs and a center leg, are positioned in a passageway of the bobbin such that the center leg of each E-core is surrounded by a respective one of the two windings. An I-bar is positioned in the center section of the bobbin between the two offset flanges with the I-bar perpendicular to the outer legs and the center legs of the two E-cores. The I-bar core increases leakage inductance between the two windings to improve the suppression of electromagnetic interference caused by common mode noise in the two windings.

Common mode inductor assembly with magnetic I bar defined leakage path

A high efficiency electronic ballast or driver circuit provides striation control at reduced power levels. The driver circuit includes a controller operating a half-bridge inverter to drive a resonant tank circuit. The controller provides asymmetric on-times to upper and lower switches of the half-bridge inverter when operating at low duty cycles (e.g., duty cycles of 50% or less). The resulting asymmetric output current eliminates striation in lamps driven by the ballast. In order to maintain light output (i.e., output current), the controller reduces the operating frequency of the half-bridge inverter to increase the gain and impedance of the resonant tank circuit.

Method to control striations in a lamp powered by an electronic ballast

An electronic ballast is provided with a filament heating circuit having a Q factor clamped at a certain range of preheat frequency. An inverter circuit includes a pair of switches coupled between positive and negative terminals of a power supply, which oscillate at an operating frequency and generate an output voltage. A main resonant tank is coupled between an inverter output and the negative power supply terminal. A filament heating resonant tank includes a primary winding of a filament heating transformer coupled on a first end in series with the resonant capacitor, first and second capacitors coupled in series between the second end of the primary winding and the negative power supply terminal. A clamping circuit coupled to the second capacitor during a preheat mode of operation clamps an amplitude of the voltage across the primary winding to an amplitude of the input voltage from the power supply.

Self-clamped resonant filament heating circuit

A bobbin apparatus and associated magnetic component is configured to reduce gap losses associated with a core air gap in a bobbin-wound magnetic component such as an inductor or transformer. The bobbin includes a step structure protruding from the winding surface between bobbin ends. The step is operable to provide spacing between the conductive windings disposed on the bobbin and the core air gap inside the bobbin axial passage. The spacing reduces stray flux interactions with the conductive winding, thereby reducing gap losses and preventing undesirable heating of the winding and core. Additional winding configurations and methods for use with the bobbin apparatus are also provided.

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Huntsville, AL, United States of America

Brandon Dyer