International Rectifier Corporation

John J Ribarich

Thomas J Ribarich

Bruno Charles Nadd

Vincent Thiery

John E Parry

A power converter provides constant load power while achieving a high power factor in a single stage configuration with reduced component count and ratings. The power converter takes a rectified line input to a switching half-bridge that supplies current to a load. A series combination of shunt switch and capacitor is connected across the load to store energy from the input and supply energy to the load. The switches are operated with conduction angles that achieve constant power supplied to the load while drawing a sinusoidal current in phase with the input voltage to achieve high power factor. The circuit provides a simplified configuration over prior power converters that may be used with a resonant load as part of an electronic ballast or an AC-to-DC converter. The power converter configuration and operation also achieves a low total harmonic distortion on the input line power.

Single stage PFC and power converter circuit

Single stage PFC and power converter unit

Two switching half-bridges are operated to achieve constant power delivered to a resonant load while achieving a high power factor. A half-bridge connected to a circuit input draws a sinusoidal current that is in phase with the input voltage to achieve the high power factor. The two half-bridges are composed of two switches each, which are operated to obtain constant load power in satisfaction of calculated conduction angles. Alternatively, the switches are operated on complementary 50% duty cycles to regulate output voltage and shape the input current waveform. Output regulation is achieved by frequency control while input current wave shaping is realized by phase shifts between the two half-bridges.

Single stage PFC &plus; ballast control circuit/general purpose power converter

An inductorless ballast including four transistors arranged in a full-bridge configuration for supplying a high voltage AC step-type signal across a fluorescent lamp. The circuit of the present invention eliminates the need for an inductor, thereby resulting in a smaller, lighter and more reliable ballast which can fit into a fluorescent lamp socket.

Inductorless ballast

A model and computer program for designing the output stage of a high frequency electronic ballast for a fluorescent lamp. The user specifies a plurality of parameters relating to the operation of the fluorescent lamp, including lamp running power, running voltage, maximum preheating voltage for the lamp, minimum running frequency for the lamp, and an input voltage for the ballast. Based upon these parameters, the computer program calculates the values for various components of the ballast, including the inductor and capacitor of the output stage, such that the preheat frequency is greater than the ignition frequency, the ignition frequency is greater than or equal to the running frequency, the preheat voltage is less than the maximum preheat voltage, and the difference between the preheat frequency and the ignition frequency is greater than about 5 kHz.

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Los Angeles, CA, United States of America

John J Ribarich