Abstract: This invention is concerned with the control and design of a LED lighting system that does not need electrolytic capacitors in the entire system and can generate light output with reduced luminous flux fluctuation. The proposal is particularly suitable, but not restricted to, off-line applications in which the lighting system is powered by the ac mains. By eliminating electrolytic capacitors which have a limited lifetime of typically 15000 hours, the proposed system can be developed with passive and robust electrical components such as inductor and diode circuits, and it features long lifetime, low maintenance cost, robustness against extreme temperature variations and good power factor. No extra electronic control board is needed for the proposed passive circuits, which can become dimmable systems if the ac input voltage can be adjusted by external means. Optionally, the power sensitivity of the load against AC voltage fluctuation may be controlled.

Abstract: This invention is concerned with the control and design of a LED lighting system that does not need electrolytic capacitors in the entire system and can generate light output with reduced luminous flux fluctuation. The proposal is particularly suitable, but not restricted to, off-line applications in which the lighting system is powered by the ac mains. By eliminating electrolytic capacitors which have a limited lifetime of typically 15000 hours, the proposed system can be developed with passive and robust electrical components such as inductor and diode circuits, and it features long lifetime, low maintenance cost, robustness against extreme temperature variations and good power factor. No extra electronic control board is needed for the proposed passive circuits, which can become dimmable systems if the ac input voltage can be adjusted by external means.

Abstract: This invention is concerned with the control and design of a LED lighting system that does not need electrolytic capacitors in the entire system and can generate light output with reduced luminous flux fluctuation. The proposal is particularly suitable, but not restricted to, off-line applications in which the lighting system is powered by the ac mains. By eliminating electrolytic capacitors which have a limited lifetime of typically 15000 hours, the proposed system can be developed with passive and robust electrical components such as inductor and diode circuits, and it features long lifetime, low maintenance cost, robustness against extreme temperature variations and good power factor. No extra electronic control board is needed for the proposed passive circuits, which can become dimmable systems if the ac input voltage can be adjusted by external means.

Abstract: This invention is concerned with the control and design of a LED lighting system that does not need electrolytic capacitors in the entire system and can generate light output with reduced luminous flux fluctuation. The proposal is particularly suitable, but not restricted to, off-line applications in which the lighting system is powered by the ac mains. By eliminating electrolytic capacitors which have a limited lifetime of typically 15000 hours, the proposed system can be developed with passive and robust electrical components such as inductor and diode circuits, and it features long lifetime, low maintenance cost, robustness against extreme temperature variations and good power factor. No extra electronic control board is needed for the proposed passive circuits, which can become dimmable systems if the ac input voltage can be adjusted by external means.

Abstract: LED illumination systems are formed with a suitable choice of LED and/or heatsink, such that an optimum operating power is identified using computer modeling for a desired output luminous flux, given the constraints of the rated power of the LED and the heatsink.

Abstract: Various circuit configurations and topologies are provided for single and multi-phase, single-level or multi-level, full and half-bridge rectifiers in which diodes are replaced by combinations of voltage-controlled self-driven active switches, current-controlled self-driven active switches and inductors in order to reduce the effects of conduction loss in the diodes.

Abstract: An EMI filter for use between a power source and an electronic product is formed of at least one planar element including a pair of opposed coreless spiral planar windings, and a planar capacitor. This enables the integration of common mode and differential mode filters into integrated planar structures. Furthermore the planar EMI filter may be combined with an active filter element to provide a hybrid EMI filter comprising both passive and active elements with superior performance.

Abstract: This invention provides an electronic control method for a planar inductive battery charging apparatus on which one or more electronic loads such as mobile phones, MP3 players etc can be placed and charged simultaneously. The power control circuit of the charging pad consists of two power conversion stages. Depending on the nature of the input power supply, the first power stage is an AC-DC power converter with variable output voltage control and a second stage is a DC-AC power inverter with constant current control. The combination of the two stages provides power control of the charging pad and generates AC magnetic flux of ideally constant magnitude over the charging areas within a group of primary windings that are excited.

Abstract: Methods and principles are described for systematizing localized charging, load identification and bi-directional communication in a planar battery charging system. Also described is control circuitry for selectively energizing a primary winding when a load is placed on the platform. The optimization of the size of the receiver winding compared to the transmitter winding is discussed, while the associated communication methods include techniques for load identification, compatibility checks, hand-shaking and communication of charging status.

Abstract: A battery pack for an electronic device comprises battery cells, a battery charging circuit, and an energy receiving element adapted to receive power from a planar inductive charging system. The energy receiving element has an inductance and a capacitor is connected to the energy receiving element and forms a resonant tank therewith. A diode rectifier and a DC capacitor are connected to the energy receiving element to provide a rectified DC voltage that can be fed from the energy receiving element to said battery charging circuit. The energy receiving element may comprise a soft magnetic sheet with a coil wound around its edges, or a coil formed on a printed circuit board, or a combination of the two. The energy receiving element may be formed integrally with the battery pack, or may be provided as a separate component that can be added to an existing battery.

Abstract: An EMI filter for use between a power source and an electronic product is formed of at least one planar element including a pair of opposed coreless spiral planar windings, and a planar capacitor. This enables the integration of common mode and differential mode filters into integrated planar structures.

Abstract: In order to achieving wide dimming range for compact and tubular fluorescent lamps, two novel control approaches are proposed. (i) Novel techniques for suppressing oscillatory effects in the Triac circuit so as to maintain stable Triac operation over a wide firing angle range and (ii) a hybrid dimming control technique in the ballast inverter circuit for achieving wide dimming range from 100% to about 3%. Concerning point (i) both dissipative and non-dissipative energy absorption schemes (EAS) are proposed to suppress the transient effects in the Triac circuit when the Triac is turned on. The essence of the EAS is to ensure that the Triac circuit can be operated in a stable manner without oscillations or inadvertent turn-off. With respect to pint (ii) a hybrid dimming method is proposed in which unlike traditional control methods that use inverter frequency control only for dimming purposes, both dc link voltage and inverter frequency are varied.

Abstract: Novel designs for printed circuit board transformers, and in particular for coreless printed circuit board transformers designed for operation in power transfer applications, in which shielding is provided by a combination of ferrite plates and thin conductive sheets.

Abstract: The present invention provides an apparatus and method for tracking the maximum power point of a solar panel. A pulsewidth-modulated converter, for example a SEPIC or Cuk converter, is provided between the output of the panel and the load, and a perturbation is introduced into a switching parameter of the converter.

Abstract: Novel designs for printed circuit board transformers, and in particular for coreless printed circuit board transformers designed for operation in power transfer applications, are disclosed in which shielding is provided by a combination of ferrite plates and thin conductive sheets.

Abstract: In order to achieving wide dimming range for compact and tubular fluorescent lamps, two novel control approaches are proposed. (i) Novel techniques for suppressing oscillatory effects in the Triac circuit so as to maintain stable Triac operation over a wide firing angle range and (ii) a hybrid dimming control technique in the ballast inverter circuit for achieving wide dimming range from 100% to about 3%. Concerning point (i) both dissipative and non-dissipative energy absorption schemes (EAS) are proposed to suppress the transient effects in the Triac circuit when the Triac is turned on. The essence of the EAS is to ensure that the Triac circuit can be operated in a stable manner without oscillations or inadvertent turn-off. With respect to pint (ii) a hybrid dimming method is proposed in which unlike traditional control methods that use inverter frequency control only for dimming purposes, both dc link voltage and inverter frequency are varied.

Abstract: The present invention provides an apparatus and method for tracking the maximum power point of a solar panel. A pulsewidth-modulated converter, for example a SEPIC or Cuk converter, is provided between the output of the panel and the load, and a perturbation is introduced into a switching parameter of the converter.

Abstract: This invention relates to dimmable electronic ballasts for particular use with fluorescent lamps.

Abstract: Novel designs for printed circuit board transformers, and in particular for coreless printed circuit board transformers designed for operation in power transfer applications, are disclosed in which shielding is provided by a combination of ferrite plates and thin copper sheets.

Abstract: Novel designs for printed circuit board transformers, and in particular for coreless printed circuit board transformers designed for operation in power transfer applications, are disclosed in which shielding is provided by a combination of ferrite plates and thin copper sheets.