Abstract: A method is provided for preventing islanding of a power source connected to an electric AC grid via an interface. The method senses an output voltage waveform of the interface, controls an output current waveform of the interface to track a reference current waveform having a mathematical relationship with the sensed output voltage waveform, and discontinues the output current waveform when the output voltage waveform is sensed to be outside a predetermined waveform range.

Abstract: A method for controlling a variable of a switching electrical circuit detects values for each of a first waveform and of a second waveform in the switching circuit at a beginning of and at a predetermined instant during a switching interval of a switching operation of the electrical circuit, both of the first and second waveforms are perturbed by the switching operation, and evaluates the variable based on the corresponding values of both the first waveform and the second waveform detected at the beginning and at the predetermined instant during the switching interval. The method further adjusts an operating point of the circuit based on a change in the variable between the two evaluations so as to maximize the variable.

Abstract: In an electrical power supply having a plurality of switching power converter circuits and configured to supply a voltage to an electrical load, a method of controlling a duty cycle of at least one switch of one of the plurality of switching power converter circuits includes determining a storage voltage produced by the one of the plurality of energy storage devices. The method further includes determining an average storage voltage corresponding to an average of storage voltages produced by each of the plurality of energy storage devices. The method further includes determining at least one control signal as a function of the storage voltage, the average storage voltage, and a reference voltage. The method further includes controlling the duty cycle of the at least one switch of the one of the plurality of switching power converter circuits based upon the at least one control signal.

Abstract: An apparatus and method for supplying energy to a load includes an energy recharge unit, an energy storage unit, an energy converter connected to the energy recharge unit, the energy converter being capable of transferring energy at a power level from the energy recharge unit to an output node, the power level being determined by a power transfer controller, and a bi-directional energy converter connected to the energy storage unit and to the output node. The bi-directional energy converter is capable of converting energy of varying voltages from the energy storage unit to energy of varying current levels to supplement the transferred energy with energy from the energy storage unit so as to maintain a constant voltage on the output node. The bi-directional energy converter is capable of converting the transferred energy to provide charging energy to the energy storage unit when the transferred energy exceeds a demand level of the load while maintaining the constant voltage at the output node.

Abstract: The invention recognizes that filter size can be reduced substantially as power factor is permitted to deviate below unity in systematic ways. Preferred methods of the invention provide specific, computable waveforms that permit use of a minimum filter size given a desired target power factor.

Abstract: A system for controlling a commutation of a load current is provided. The system comprises a AC-to-AC converter that includes a plurality of switching elements, an energy source that provides an oscillating voltage and is connected to the converter, an electrical load connected to the converter, and a controller that controls the converter, and monitors the oscillating voltage and the load current delivered to the electrical load. The controller determines a plurality of machine states of the converter, each of the plurality of machine states representing a corresponding conducting set of the plurality of switching elements, and controls switching between the plurality of machine states based on polarity commutations of the load current in the electrical load and polarity commutations of the oscillating voltage.

Abstract: A startup circuit for starting a power converter for converting an input voltage to an output voltage includes a switch connected in series with a resistive element. The startup circuit is connected in parallel with a trigger switch in the power converter for enabling the power converter to generate the output voltage. When closed or activated, the switch in the startup circuit charges an energy storing device in the power converter. The energy storing device activates the trigger switch as the charge is released.

Abstract: A power supply in an embodiment of the invention includes a plurality of dc—dc switching power converters, each of which has its input isolated from its output. The power converters are arranged with their respective inputs being series connected and their respective outputs being parallel connected in an embodiment of the invention. In another embodiment of the inputs are parallel connected and the outputs series connected. Each power converter includes an input filter in each of said dc—dc switching power converters and an output filter. Each power converter includes a sensorless current mode control circuit controlling its switching duty ratio.

Abstract: A method for generating pulse width modulated control signal has the steps of providing a base carrier waveform, segmenting the base carrier waveform into a plurality of carrier waveforms, and providing at least one modulating signal. The first and second waveforms are compared to the at least one modulating signal to produce first and second comparator outputs, which are then mathematically combined to produce a pulse width modulated control signal.

Abstract: A method for generating pulse width modulated control signal has the steps of providing a base carrier waveform, segmenting the base carrier waveform into a plurality of carrier waveforms, and providing at least one modulating signal. The first and second waveforms are compared to the at least one modulating signal to produce first and second comparator outputs, which are then arithmetically combined to produce a pulse width modulated control signal.

Abstract: In any steady-state optimization problem, the output being optimized could be a nonmonotonic function of the controlled variable. Often the output is dependent on the temperature, the load impedance, and other unknown and variable quantities. Thus, it is very useful to have an automatic tuning scheme that will take the system to the desired operating point using only input and output information. The present invention is a generalized tuning scheme that uses the correlation between changes in the input and corresponding changes in the output to tune the operating point. In general terms, the present invention utilizes a correlation function between the controlled variable and a perturbed waveform. When the system reaches the desired operating point, the correlation goes to zero and the system converges. This corresponds to the point at which the derivative of the output with respect to the input is zero. This tuning scheme is appropriate for any tuning problem which has a single maximum or minimum.

Abstract: A switched capacitor system for automatic battery equalization can be used with series coupled batteries as well as primary and backup batteries which are alternately couplable to a load. The system includes a plurality of capacitors and a plurality of switching elements. Each of the capacitors is switched back and forth between a predetermined pair of batteries for the purpose of transferring charge therebetween and equalizing the output voltages of each of the batteries in the pair. The capacitors and switching elements can be configured in a modular fashion. Multiple modules can be used, for example, in combination with multiple batteries which are series coupled to one another. The system could be used in electric vehicles and in battery back-up systems of all types.

Abstract: An active filter provides ripple cancellation in a DC-DC converter. The feedforward filter applies to any converter with an output filter inductor. The filter is inherently stable, performs in both continuous and discontinuous conduction modes, and applies to resonant converters. A suitable linear amplifier, combined with a current transformer, results in a low loss implementation. An adaptive tuning scheme compensates for inductance variation and drift. The filter is usable with buck, push-pull, and boost converter topologies. The result is output ripple below 10 mV.sub.RMS. The filter is effective on converters with outputs as low as 2 V and currents beyond 30 A.

Abstract: In accordance with the invention, a touch panel includes an electrically conductive film of a first resistivity which extends over a first area of a base plate. Regions of a resistivity higher than the first resistivity, such as discontinuities in the film, are positioned in this first area. These discontinuities are located so as to enhance the uniformity of an electric field which is established in a touch sensing portion of the film.

Abstract: A touch panel has panel scanning signals selectively applied to the four sides of a touch sensing surface of the panel so as to establish alternating current voltage gradients in desired directions across the touch sensing surface. When the panel is touched, touch signals result and are utilized by a touch location circuit in determining the location of touch. The impedence touch current resulting from a user's touch may also be determined and used. The touch panel circuit automatically compensates for any variations in touch signals which occur when the touch panel is untouched and automatically nulls the touch signals under such circumstances to enhance the accuracy of touch location determination.

Abstract: A touch panel has panel scanning signals selectively applied to the four sides of a touch sensing surface of the panel so as to establish alternating current voltage gradients in desired directions across the touch sensing surface. When the panel is touched, touch signals or currents result and are utilized by a touch location circuit in determining the location of touch. The impedance touch current resulting from a user's touch may also be determined and used. The touch panel circuit automatically compensates for changes in impedance touch current, such as result when users touch the panel with ungloved and gloved fingers. An analog multiplier is included in the touch location circuit to improve noise rejection. Auto nulling and automatic frequency adjustment is included in the touch panel device, together with overcurrent protection circuitry.

Abstract: A touch panel has panel scanning signals selectively applied to the four sides of a touch sensing surface of the panel so as to establish alternating current voltage gradients in desired directions across the touch sensing surface. When the panel is touched, touch signals result and are utilized by a touch location circuit in determining the location of touch. The impedence touch current resulting from a user's touch may also be determined and used. The touch panel circuit automatically adjusts the frequency of the applied panel signals to shift this frequency away from fixed frequency interference spectra, such as due to cathode-ray tube flyback signals, in the environment in which the touch panel is used. The touch location thereby minimizes the effects of such spectra on touch location determinations.