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: There is provided a planar inductive battery charging system designed to enable electronic devices to be recharged. The system includes a planar charging module having a charging surface on which a device to be recharged is placed. Within the charging module and parallel to the charging surface is at least one and preferably an array of primary windings that couple energy inductively to a secondary winding formed in the device to be recharged. The invention also provides secondary modules that allow the system to be used with conventional electronic devices not formed with secondary windings.

Abstract: Dimming of an electrical lamp of the type driven by a ballast is provided by a reactive power device in series between the AC supply and the ballast. The reactive power device provides a variable auxiliary voltage out of phase by 90 or 270 degrees with the current such that a smaller magnitude voltage is applied to the lamp. The dimming device has a switch to enable/disable dimming. When the switch is enabled, the voltage applied to the lamp is controlled by a half-bridge inverter with a pair of totem pole power electronic switches, along with a pair of DC series capacitors and a low-pass filter.

Abstract: This invention relates to new soft-switching techniques for minimizing switching losses and stress in power electronic circuits using inverter legs. By choosing the switching frequency with specific relationships with the resonant frequency of the power electronic circuits, the proposed switching technique enables the power electronic circuits to achieve soft switching under full load and short-circuit conditions at the defined frequencies for both capacitive and inductive loads. This technique can be applied to an electronic circuit with two switches connected in totem pole configuration between two dc voltage rails or commonly known as a power inverter leg or inverter arm. Examples of these circuits are class-D power converter, half-bridge power converters and full-bridge power converters or inverters. The proposed techniques allow inverter circuits with resistive, capacitive and inductive loads to achieve soft switching.

Abstract: There is described methods and techniques for providing dimming control of low-cost fluorescent lamps that are driven by self-excited gate circuits and which are nominally non-dimmable. A dimming function is achieved by providing a variable DC voltage input to the ballast. It is possible to retroactively change existing non-dimmable lamps into dimmable lamps, or to form new low-cost dimmable fluorescent lamps.

Abstract: There is provided a planar inductive battery charging system designed to enable electronic devices to be recharged. The system includes a planar charging module having a charging surface on which a device to be recharged is placed. Within the charging module and parallel to the charging surface is at least one and preferably an array of primary windings that couple energy inductively to a secondary winding formed in the device to be recharged. The invention also provides secondary modules that allow the system to be used with conventional electronic devices not formed with secondary windings.

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: There is described methods and techniques for providing dimming control of low-cost fluorescent lamps that are driven by self-excited gate circuits and which are nominally non-dimmable. A dimming function is achieved by providing a variable DC voltage input to the ballast. It is possible to retroactively change existing non-dimmable lamps into dimmable lamps, or to form new low-cost dimmable fluorescent lamps.

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.

Abstract: Novel structures for electronically-controlled integral compact fluorescent lamps are described in which the space defined by a folded discharge tube is used to locate a housing for at least a part of the electronic-control circuitry. The housing is provided with ventilation means to allow the escape of heated air from the interior of the housing. This reduces the size of the lamp, and allows temperature sensitive components to be located in a relatively cool region. The housing can be provided with a reflective coating to improve the illumination uniformity, and if made of metal can act as a heat sink.

Abstract: Novel structures for electronically-controlled compact fluorescent lamps are described in which the space defined by a folded discharge tube is used to locate a housing for at least a part of the electronic-control circuitry. This reduces the size of the lamp, and allows temperature sensitive components to be located in a relatively cool region. The housing can be provided with a reflective coating to improve the illumination uniformity, and if made of metal can act as a heat sink.

Abstract: An electronic ballast is disclosed that is capable of operating with any fluorescent lamp within a range of nominal operating powers. The electronic ballast is capable of sensing the power rating of the lamp from the peak lamp voltage, and provides for varying the switching frequency of the ballast depending on the power rating of the lamp.

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

Abstract: Apparatus and methods are described for the voltage control of power converters in which the input and output voltages of the converter are not sensed directly but are derived from an inductor voltage which in turn is derived by sensing an instantaneous inductor current.