Motorola Corporation

Motorola Lighting, Inc.

Other

Anand K Upadhyay

Dennis L Stephens

Guang Rong Liu

John G Konopka

Edward E Li

Kasemsan Siri

Rembert R Stokes

Kenneth D Labudda

Bhadresh Mehta

Chu-Quon Lee

An electronic ballast (10) for fluorescent lamps includes a rectifier circuit (100), a boost converter (200), and an inverter (500). The boost converter (200) includes a boost control circuit (400) and a shifting circuit (300). The shifting circuit (300) provides filament preheating by maintaining the boost output voltage at a first level for a predetermined delay period following startup of the boost converter, and then increasing the boost voltage to a second level upon completion of the delay period in order to ignite and operate the lamps. In a preferred embodiment, shifting circuit (300) comprises a shunt circuit (320) and a time delay circuit (360), and inverter (400) is a series resonant half-bridge inverter.

Electronic ballast with two-step boost converter and method

A method (100) of controlling an inverter in an electronic ballast for at least one gas discharge lamp protects the inverter from damage due to lamp fault conditions, and provides enhanced noise immunity and multiple ignition attempts for low-temperature lamp starting. The method (100) includes repeating a filament preheating step and a frequency shifting step up to a predetermined number of times in order to facilitate lamp ignition under low-temperature conditions and to verify the legitimacy of a detected lamp fault.

Inverter control method for electronic ballasts

An electronic ballast (300) for powering at least one gas discharge lamp (10) includes an inverter (400), an output circuit (700), a lamp fault detection circuit (800), and an inverter control circuit (500). Ballast (300) operates according to an inverter control method (100) that includes repeating a filament preheating step and a frequency shifting step up to a predetermined number of times in order to facilitate lamp ignition under low-temperature conditions and to verify the legitimacy of a lamp fault. Inverter control circuit (500) is well-suited for implementation as a custom integrated circuit. Ballast (300) optionally includes an overcurrent detection circuit (820') with an adjustable lamp fault detection threshold that provides decreased sensitivity during lamp starting and enhanced protection after lamp ignition.

Electronic ballast with inverter control circuit

An electronic power supply circuit (50) that includes a rectifying circuit (14), a boost converter (16), an in-rush current reduction circuit (52), and a bulk capacitor (18). The in-rush current reduction circuit (52) includes an in-rush current limiting resistor (54) and a bypass capacitor (56) that are connected in parallel with each other. An improved version of the in-rush current reduction circuit (52) includes a bypass diode (58) connected in parallel with the in-rush current limiting resistor (54) and bypass capacitor (56) which is oriented to provide a path for current flowing out of bulk capacitor (18). One particular application of the disclosed circuit is for use in an electronic ballast for fluorescent lamps.

In-rush current reduction circuit for boost converters and electronic

A protection method (10) and protection circuit (500) for protecting an inverter (300) in an electronic preheat ballast (100) for powering at least one fluorescent lamp (902). The inverter (300) includes a first inverter switch (306), a second inverter switch (310), an output circuit (800), and an inverter driver circuit (400) having a drive frequency. The protection circuit (500) comprises a frequency shift circuit (600), a latch circuit (700), a current source network (520), a current sensing circuit (510), and a DC supply capacitance (502). The protection method (10) includes the steps of (a) providing a filament preheat period by initially setting the drive frequency at a first frequency, (b) shifting the drive frequency to a second frequency for igniting and operating the lamps, (c) changing the drive frequency back to the first frequency in response to a lamp fault, and (d) providing, upon correction of the lamp fault, a filament preheat period prior to attempting to ignite and operate the lamps.

Inverter protection method and protection circuit for fluorescent lamp

A transformer (202) has a bobbin (2) which has an inner portion (104) supporting an inner electrical winding (140) and having a magnetic core recess. The inner portion is located within an outer portion (4) supporting an outer electrical winding (40). The inner portion further has an end with a termination connected to the inner winding, an annular recess (126) in which the inner winding is situated, and a channel (132) communicating between the termination end of the inner portion and a remote end of the annular recess. The channel is positioned radially inwardly of the first annular recess and accommodates a portion of the inner winding. By providing the channel radially inwardly of the annular recess, winding wire can extend between the termination end of the inner portion and the remote end of the annular recess across the annular recess without significantly increasing the size of the inner portion and without increasing the gap between the inner and outer portions. This allows the size, weight and cost of a transformer built with the bobbin to be reduced, and improves the transformer's magnetic performance. The channel also allows layered windings terminating at the same end of the inner portion to be formed from an odd number of winding passes, reducing corona voltage breakdown effect and so prolonging the practical life of the windings. This also allows the inner portion to be wound uninterruptedly by machine without manual intervention.

Bobbin for electrical windings

An integrated EMI/RFI Filter Magnetic has differential and common mode inductors wound about an I-Core. The I-Core is juxtaposed with an E-Core, with the end surfaces of the E-Core legs facing the I-Core. The magnetic has a substantially closed magnetic path for the differential inductors and the common mode inductors.

Integrated common mode and differential mode inductor device

A parallel resonant converter as disclosed having in one embodiment a variable inductance and having a control circuit which operates the switches of the converter under zero voltage switching conditions and under continuous conduction mode by maintaining the quality factor of the resonant circuit generally equal to the DC conversion ratio.

Growing community of inventors

Libertyville, IL, United States of America

Anand K Upadhyay