Patent•
Gate driver for a full-bridge lossless switching device
07 Mar 1988-
TL;DR: In this paper, a control circuit for a full bridge switching converter including power FET switching devices is presented, including a gate driver with a voltage sensor circuit, which senses the precise instant to gate the power switch on in order to achieve substantially lossless switching by the converter.
Abstract: A control circuit for a full bridge switching converter including power FET switching devices. The control circuit including a gate driver with a voltage sensor circuit which senses the precise instant to gate the power FET on in order to achieve substantially lossless switching by the converter.
Citations
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Patent•
11 Feb 2004
TL;DR: In this paper, a CCFL power converter circuit is provided using a high-efficiency zerovoltage-switching technique that eliminates switching losses associated with the power MOSFETs.
Abstract: A CCFL power converter circuit is provided using a high-efficiency zero-voltage-switching technique that eliminates switching losses associated with the power MOSFETs. An optimal sweeping-frequency technique is used in the CCFL ignition by accounting for the parasitic capacitance in the resonant tank circuit. Additionally, the circuit is self-learning and is adapted to determine the optimum operating frequency for the circuit with a given load. An over-voltage protection circuit can also be provided to ensure that the circuit components are protected in the case of open-lamp condition.
264 citations
Patent•
16 Apr 2009
TL;DR: In this article, a controller for use with a power converter including a switch configured to conduct to provide a regulated output characteristic at an output of the power converter, and method of operating the same is presented.
Abstract: A controller for use with a power converter including a switch configured to conduct to provide a regulated output characteristic at an output of the power converter, and method of operating the same In one embodiment, the controller includes a linear control circuit, coupled to the output, configured to provide a first control signal for the switch as a function of the output characteristic The controller also includes a nonlinear control circuit, coupled to the output, configured to provide a second control signal for the switch as a function of the output characteristic The controller is configured to select one of the first and second control signals for the switch in response to a change in an operating condition of the power converter
162 citations
Patent•
04 Jan 2002
TL;DR: In this paper, a PWM signal generator and phase delay array are used to generate a plurality of PWM signals, where each of the phased signals regulates power to a respective load.
Abstract: A sequential burst mode regulation system to deliver power to a plurality of loads. In the exemplary embodiments, the system of the present invention generates a plurality of phased pulse width modulated signals from a single pulse width modulated signal, where each of the phased signals regulates power to a respective load. Exemplary circuitry includes a PWM signal generator, and a phase delay array that receives a PWM signal and generates a plurality of phased PWM signals which are used to regulate power to respective loads. A frequency selector circuit can be provided that sets the frequency of the PWM signal using a fixed or variable frequency reference signal.
151 citations
Patent•
03 Apr 2001
TL;DR: In this article, an electronic ballast controller for lamps or tubes is described, which includes filament heating circuitry (26) and dimming circuitry (28). But the authors do not specify the type of the filament heating circuit.
Abstract: An electronic ballast for lamps or tubes is provided. In one embodiment the present invention includes a ballast controller (12) that includes filament heating circuitry (26) and dimming circuitry. The filament heating circuitry (26) may include preheat dimming circuits which preheat the filaments for a predetermined time period prior to striking the lamp, and steady-state heating circuitry (28) that continually heats the filaments during steady state operation of the lamp (20). The steady state heating circuitry (28) may be adapted to heat the filaments inversely proportional to the dim desired value of the lamp (20). The dimming circuitry may include conventional analog dimming and/or burst mode dimming to define a wide range of dimming characteristics for the lamp.
97 citations
Patent•
15 Apr 2003
TL;DR: In this article, a power supply system for a multiple lamp LCD panel is provided, where the primary sides of each transformer are coupled in series and each lamp is coupled to two secondary sides of the transformers, thereby reducing the problems associated with longer CCFL tubes.
Abstract: A power supply system is provided for a multiple lamp LCD panel. In one aspect, the power supply includes a plurality of transformers for driving a plurality of respective CCFLs. The primary sides of each transformer are coupled in series to thereby reduce the stress on each transformer. For LCD panels that include longer CCFLs, a power supply is provided that includes a plurality of transformers for driving a plurality of respective CCFLs. The primary sides of each transformer are coupled in series and each lamp is coupled to two secondary sides of the transformers, thereby reducing the problems associated with longer CCFL tubes. In any of the embodiments, the power supply can be adapted to convert a high voltage DC signal to high voltage AC used to power the lamps.
91 citations
References
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TL;DR: In this paper, a low-power breadboard operating at 200-300 kHz has been built for switching power supplies and battery chargers, which can operate in either the step-up or step-down mode.
Abstract: Transistor dc-dc converters which employ a resonant circuit are described. A resonant circuit is driven with square waves of current or voltage, and by adjusting the frequency around the resonant point, the voltage on the resonant components can be adjusted to any practical voltage level. By rectifying the voltage across the resonant elements, a dc voltage is obtained which can be either higher or lower than the input dc voltage to the converter. Thus, the converter can operate in either the step-up or step-down mode. In addition, the switching losses in the inverter devices and rectifiers are extremely low due to the sine waves that occur from the use of a resonant circuit (as opposed to square waves in a conventional converter); also, easier EMI filtering should result. In the voltage input version, the converter is able to use the parasitic diode associated with an FET or monolithic Darlington, while in the current input version, the converter needs the inverse blocking capability which can be obtained with an IGT or GTO device. A low-power breadboard operating at 200-300 kHz has been built. Two typical application areas are switching power supplies and battery chargers. The converter circuits offer improvements over conventional circuits due to their high efficiency (low switching losses), small reactive components (high-frequency operation), and their step-up/stepdown ability.
371 citations
Patent•
31 Oct 1983TL;DR: In this paper, a compact electrical power supply which derives electrical energy from a low frequency medium voltage source (e.g., a 120 V 60 Hz ac main), and converts the electrical energy to a low voltage format suitable for solid state signal processing equipment is presented.
Abstract: The present invention relates to a compact electrical power supply which derives electrical energy from a low frequency medium voltage source (eg a 120 V 60 Hz ac main), and converts the electrical energy to a low voltage format suitable for solid state signal processing equipment The supply entails in succession bridge rectification means, a dc-dc boost converter, a capacitor storage bank, and a half bridge converter, either resonantly or non-resonantly operated The converters operate at frequencies substantially above audible frequencies in the interests of compactness The design provides a high input power factor (inductive) with minimum EMT, and provides a lengthened voltage hold up after loss of power
203 citations
Patent•
28 Sep 1984TL;DR: In this paper, the duty cycle of the frequency signal is adjusted so that the frequency signals are provided in bursts during low load conditions, thereby minimizing circulating currents while maintaining the output voltage with dosed loop frequency control.
Abstract: 57 A control for a voltage fed series resonant inverter includes controllable switch means (83, 85) which supplies square wave voltage signals to a resonant series circuit (95; 97). The output of the inverter is coupled to a rectifier (99) to provide dc power to a load. The control comprises summer means (58) for comparing a commanded dc voltage (Eo) to an actual dc output voltage and providing an error signal. An oscillator (64) responsive to the error signal generates a frequency signal that is coupled to the controllable switch means (83, 85) to vary the frequency of the square wave voltage supplied to the resonant circuit. The duty cycle of the frequency signal is adjusted so that the frequency signal is provided in bursts during low load conditions thereby minimizing circulating currents while maintaining the output voltage with dosed loop frequency control.
100 citations
Patent•
22 Jun 1987TL;DR: In this article, a resonant forward converter at a switching frequency of 10 MHz provides a small volume point-of-load converter for distributed power systems, where the leakage inductance is made negligibly small relative to the magnetizing inductance of the transformer.
Abstract: A resonant forward converter at a switching frequency of 10 MHz provides a small volume point-of-load converter for distributed power systems. The leakage inductance of a transformer is made negligibly small relative to the magnetizing inductance of the transformer. This enables a resonant controllable switch on the primary side of a transformer and a secondary side rectified diode to be switched either on or off at the same time. The capacitance across the primary side switch and the secondary side diode rings with a resonant inductor connected in parallel with the transformer. Both the switch and diode, therefore, have zero voltage switching transitions. Further, the resonant inductor being connected in parallel with the transformer provides a resonant ring that is independent of load.
99 citations
Patent•
03 Nov 1982TL;DR: In this article, a series resonant dc-dc converter employing power transistors as the switching elements generates a high dc output voltage (150 kilovolts) to drive an X-ray tube.
Abstract: A resonant dc-dc converter employing power transistors as the switching elements generates a high dc output voltage (150 kilovolts) to drive an X-ray tube. The converter is configured such that the resonating circuit elements can be realized using the transformer parasitic elements. Voltage step up is achieved due to the transformer turns ratio as well as the resonant rise of voltage across the energy storage elements of a series resonant circuit.
99 citations