2528 results about "Peak current" patented technology

The LED brightness control system for a wide range of luminance control includes a brightness control module that provides a pulse width modulation (PWM) control signal and a peak current control signal. A pulse width modulation (PWM) converter circuit receives the PWM control signal and converts it to a PWM signal. A multiplier receives the PWM signal and the peak current control signal from the brightness control module and multiplies the same to provide a light emitting diode (LED) current control signal with a variable “on” time as well as variable “on” level. A voltage-controlled current source utilizes the LED current control signal and an LED current feedback signal for providing an LED current. An LED illuminator array receives the LED current. A current sensing element connected to the LED illuminator array for providing an LED current feedback signal representing LED peak current. The voltage-controlled current source controls a drive voltage to the LED illuminator array at a commanded level.

A direct current arc fault circuit interrupter includes separable contacts and a trip circuit to trip open the contacts. The trip circuit includes a number of alternating current sensors structured to sense a current flowing through the separable contacts, a number of filter circuits cooperating with the AC current sensors to output a number of AC signals, a number of peak detectors cooperating with the filter circuits to output a number of peak current signals, and a processor cooperating with at least the peak detectors. The processor inputs the number of peak current signals as a plurality of peak current signals or inputs the number of peak current signals and determines the plurality of peak current signals. The processor also determines if the peak current signals exceed corresponding predetermined thresholds for a predetermined time, and responsively causes the contacts to trip open.

An exemplary apparatus embodiment provides for controlling current supplied to solid state lighting, such as light emitting diodes. An exemplary apparatus comprises a memory adapted to store a plurality of current parameters; and a control circuit adapted to modulate an energizing cycle time period for providing a substantially constant DC average current to the solid state lighting in response to a selected current parameter of the plurality of current parameters. In an exemplary embodiment, the control circuit modulates a current provided to the solid state lighting in response to a predetermined minimum current level (IMIN) parameter and a predetermined peak current level (IP) parameter, such that the DC average current level (IO) is substantially proportional to one-half of a sum of a predetermined peak current level (“IP”) and a predetermined minimum current levelIM(IO∝IP+IMIN2).

Disclosed herein are methods and apparatus for determining analyte concentration in a rapid and accurate manner. The methods include depositing a physiological sample in an electrochemical cell and finding a first and second current transient. Peak current values are obtained from the first and second peak current values and used to reduce the influence of interferents in a current value. Based on this “corrected” current value, an accurate analyte concentration can be determined.

The present invention provides a method and apparatus for controlling the thermal stress in lighting devices, for example light-emitting elements, that are exposed to large thermal gradients typically upon start-up, for example light-emitting elements operating in relatively cold ambient environments. The present invention provides an apparatus that can reduce this thermal stress, wherein the apparatus comprises a temperature determination mechanism for evaluating the temperature of the light-emitting elements prior to activation, and a control system to control the drive current such that it is gradually ramped up to the desired steady state peak current value, wherein the ramping of the drive current is dependent on the evaluated temperature of the light-emitting element.

A fly-back power converter has a current-estimating control loop that senses the primary output current in a transformer to control the secondary output. A primary-side control circuit switches primary current through the transformer on and off. A discharge time when a secondary current through an auxiliary winding of the transformer is flowing is generated by sampling a voltage divider on an auxiliary loop for a knee-point. A normalized duty cycle is calculated by multiplying the discharge time by a current that is proportional to the switching frequency and comparing to a sawtooth signal having the switching frequency. The peak of a primary-side voltage is sensed from the primary current loop and converted to a current and multiplied by the normalized duty cycle to generate an estimated current. An error amp compares the estimated current to a reference to adjust the oscillator frequency and peak current to control primary switching.

A switching power converter detects low load conditions based on the ratio of a first peak current value for peak current switching in constant voltage regulation mode to a second peak current value for peak current switching in constant current regulation mode. The power supply load is considered to have a low load if the ratio is lower than a predetermined threshold. Once a low load condition is detected, the switching frequency of the switching power converter is reduced to a level that minimizes switching loss in the power converter. In addition, the switching power converter also adjusts the switching frequency according to the sensed input line voltage. An offset is added to the switching period to reduce the switching frequency of the switching power converter, as the input line voltage is increased.

A solid-state light engine comprised of light emitting diodes (LEDs) configured into a bridge rectifier with a current limiting module coupled to the LED bridge rectifier. The light engine may be packaged for high temperature operation. Optionally, the LEDs comprise wavelength-converting phosphors with a persistence that is a multiple of the peak to peak current period, to smooth and mask ripple frequency pulsation of emitted light.

A dimmable, light-emitting diode (LED) power supply adapted to provide a direct current (DC), constant current (“constant current source”) from a conventional, phase-controlled 120 VAC, 60 Hz power source is disclosed. The constant current source of the present invention utilizes two processes to control dimming. In a first process, the phase angle of the input voltage is used to control the duty cycle of a line frequency pulse width modulation (PWM). In a second process, a proportional-current limit adjustment is used to control the average current to the LED during the ON time of the line frequency by PWM. As a result, at relatively low phase angles, peak currents can be lowered, reducing flicker and improving the audible noise levels generated by the circuit.

System and method for regulating a power converter. The system includes a first comparator configured to receive a first input signal and a second input signal and generate a first comparison signal based on at least information associated with the first input signal and the second input signal, a pulse-width-modulation generator configured to receive at least the first comparison signal and generate a modulation signal based on at least information associated with the first comparison signal, a driver component configured to receive the modulation signal and output a drive signal to a switch to adjust a primary current flowing through a primary winding of the power converter, and a voltage-change-rate detection component configured to sample the feedback signal to generate a first sampled signal for a first modulation period and to sample the feedback signal to generate a second sampled signal for a second modulation period.

System and method for regulating an output of a power conversion system. An example system controller includes a signal generator and a modulation and drive component. The signal generator is configured to receive at least a first signal indicating a magnitude of an input voltage received by a primary winding of a power conversion system and receive a second signal indicating a magnitude of a primary current flowing through the primary winding, and generate a third signal. The modulation and drive component is configured to receive at least the third signal, generate a drive signal based on at least information associated with the third signal, and output the drive signal to a switch to affect the primary current.

A primary side sensing power control system and method for constant current control that utilizes a relationship that involves the measured reset-time from the previous cycle to determine the primary side peak current and off-time for the next cycle. This control mechanism does not need the knowledge of input voltage or magnetizing inductance. Therefore, it removes the sensitivities of input voltage and magnetizing inductance to the output current limit. Furthermore, it uses a time measurement instead of a voltage measurement for the current calculation which in many cases is easier to perform.

A power conversion circuit operates in a discontinuous switching mode over a wide range of loading conditions and varies a coil peak current to maintain efficiency over the wide range of loading conditions. The coil peak current is adjustable based at least in part on a feedback signal generated in response to a load condition.

Detection of abnormal signal traces in electrochemical measurements generated using an electrochemical test strip to which a potential is applied allows for an indication of an erroneous analyte determination. The current trace has an expected shape in which a peak current is observed a time tpeak after which there is a decrease in current. To detect abnormal signal traces, the time tpeak is determined experimentally and compared with an expected value, t′peak, and if the difference between the two values to over a predetermined threshold, an error message is provided to the user instead of a test result. The value of t′peak is determined as a function of a mobility term that is determined during a potentiometry phase following the amperometric measurements.

A single stage, single switch, input-output isolated converter configuration which uses a hybrid combination of forward and flyback converters is disclosed. The converter operates at a high input power factor with a regulated DC output voltage. It makes use of a novel control scheme utilizing duty cycle control at two discrete operating frequencies. Although the invention employs two frequencies, it does not use a continuous frequency variation. This configuration has the advantage of reduced peak current stresses on the components and is specifically suited for ‘buck’ applications where low DC output voltages (e.g. 24V, 48V) are needed. This configuration will be of specific interest to industries associated with battery charging and uninterruptible power supply (UPS) systems. Apart from having several competitive features compared with prior art techniques, the dual frequency operation scheme reduces the amplitude of its noise spectrum by spreading it over a wider frequency range thus making it more electromagnetic compatible.

A circuit interrupter includes band pass filters cooperating with a current sensor to output bands having different, non-overlapping ranges of frequencies, peak detectors cooperating with the filters to detect corresponding peak current values, envelope detectors cooperating with the filters to detect corresponding occurrences from the bands being within corresponding predetermined magnitude ranges, a counter counting the occurrences, and a processor providing and disabling series arc detection when sensed current is greater than a first predetermined value. The processor determines tallies responsive to peak current values exceeding corresponding thresholds, determines series arcing from sensed current being less than the first predetermined value for a predetermined time, the tally for a current half-cycle being nonzero, and a count for the current half-cycle being different than the count for an immediately previous half-cycle of like polarity by at least a second predetermined value. A series chaos accumulator is increased responsive to series arcing.

Apparatus and method for generating controlled-linewidth laser-seed-signals for high-powered fiber-laser amplifier systems. In some embodiments, the natural chirp (frequency change of laser light over a short start-up time) of a DBR laser diode when driven by pulsed current is used to broaden the linewidth of the laser output, while adjusting the peak current and / or the pulse duration to obtain the desired linewidth.

A laminated-type varistor includes a laminated structure and a pair of external electrodes disposed on a surface of the laminated structure. The laminated structure includes effective sintered body layers and internal electrodes. The internal electrodes are connected to the external electrodes and are disposed apart from each other in the direction perpendicular to lamination surfaces. Each of the internal electrodes has a multilayer electrode structure in which a plurality of electrode layers are arranged in layers while an ineffective sintered body layer is disposed therebetween. The laminated-type varistor has increased maximum peak current and maximum energy and reduction in clamping voltage.

An electric arc device and methods to build up, clad, join, or overlay an alloyed metal onto a parent metal with minimal admixture. The methods employed in the electric arc device provide a high frequency waveform with a high amplitude pulse, a low amplitude background current, and a special shorting routine, to alleviate the problem of generating too much ad-mixture. A fast transition from a peak current level to a background current level along with a shorting response and a plasma boost pulse reduces the droplet size and reduces the heat input required to achieve good welding performance.

A pulsed waveform welding operation is implemented by reference to a commanded wire feed speed set by an operator. The wire feed speed is set on a wire feeder, and a signal representative of the commanded wire feed speed is applied to a power supply. The power supply control circuitry references a look-up table in which pulsed waveform parameters are provided based upon wire feed speed. The parameters may include multiple parameters such as pulse frequency, peak current, background current, and current ramp rates. The control circuitry commands power conversion circuitry to generate the commanded waveform as a function of the commanded wire feed speed.