4357 results about "Voltage variation" patented technology

A system and method for combining power from DC power sources. Each power source is coupled to a converter. Each converter converts input power to output power by monitoring and maintaining the input power at a maximum power point. Substantially all input power is converted to the output power, and the controlling is performed by allowing output voltage of the converter to vary. The converters are coupled in series. An inverter is connected in parallel with the series connection of the converters and inverts a DC input to the inverter from the converters into an AC output. The inverter maintains the voltage at the inverter input at a desirable voltage by varying the amount of the series current drawn from the converters. The series current and the output power of the converters, determine the output voltage at each converter.

A system and method for combining power from DC power sources. Each power source is coupled to a converter. Each converter converts input power to output power by monitoring and maintaining the input power at a maximum power point. Substantially all input power is converted to the output power, and the controlling is performed by allowing output voltage of the converter to vary. The converters are coupled in series. An inverter is connected in parallel with the series connection of the converters and inverts a DC input to the inverter from the converters into an AC output. The inverter maintains the voltage at the inverter input at a desirable voltage by varying the amount of the series current drawn from the converters. The series current and the output power of the converters, determine the output voltage at each converter.

A dielectrophoretic display is shifted from a low frequency closed state to a high frequency open state via at least one, and preferably several, intermediate frequency states; the use of such multiple frequency steps reduces flicker during the transition. A second type of dielectrophoretic display has a light-transmissive electrode through which the dielectrophoretic medium can be viewed and a conductor connected to the light-transmissive electrode at several points to reduce voltage variations within the light-transmissive electrode.

A method and apparatus for efficiently charging lead-acid batteries applies small voltage steps to probe the charging efficiency of a battery being charged. The application of a voltage step causes the current to change from a base current to a surge current immediately after the voltage step, and to decay asymptotically to a plateau current after the surge current. A current ratio, defined as the difference between the plateau current and the base current divided by the difference between the surge current and the base current, is used as an indicator of the charging efficiency. The output voltage of the power supply charging the battery is then adjusted according to the measured current ratio. A current-voltage slope, defined as the difference between the plateau current and the base current divided by the magnitude of the voltage step, may also be used as an indicator of the charging efficiency for controlling the charging process. Alternatively, in a current-controlled charging process, small current steps are used to probe the charging efficiency. For a current step, the induced voltage changes are measured, and a transient-plateau voltage ratio is calculated. The charging current is then adjusted according to the calculated voltage ratio.

An integrated circuit regulates current flowing from a battery to a load without requiring an external current sense resistor. The IC includes a primary charge pump; a model charge pump; a current sense circuit, a first control circuit to force a voltage level at the output of the model charge pump to be equal to a voltage level at the output of the primary charge pump; and, a second control circuit to force a model current put out by the model charge pump to be equal to a reference current. Current passing through the primary charge pump is regulated at a level established by the capacitance value of an external flying capacitor irrespective of input voltage variation of the battery power source.

A contactless electrical energy transmission system includes a transformer having a primary winding that is coupled to a power source through a primary resonant circuit and a secondary winding that is coupled to a load through a secondary resonant circuit. The primary and secondary resonant circuits are inductively coupled to each other. A primary control circuit detects current changes through the primary resonant circuit to control the switching frequency of a controllable switching device for maintaining a substantially constant energy transfer between the primary winding and secondary winding in response to at least one of a power source voltage change and a load change. As a result, excessive circulating energy of the CEET system is minimized providing a tight regulation of the output voltage over the entire load and input voltage ranges without any feedback connection between the primary side and the secondary side.

A main power supply continuously provides a current to a power input terminal of an integrated circuit device under test (DUT). The DUT's demand for current at the power input terminal temporarily increases during state changes in synchronous logic circuits implemented within the DUT. To limit variation (noise) in voltage at the power input terminal arising from these temporary increases in current demand, a charged capacitor is connected to the power input terminal during each DUT state change. The capacitor discharges into the power input terminal to supply additional current to meet the DUT's increased demand. Following each DUT state change the capacitor is disconnected from the power input terminal and charged to a level sufficient to meet a predicted increase in current demand during a next DUT state change.

Supplying first and second measuring voltages to a source terminal of a drive transistor to obtain first and second voltage variations at the source terminal of the drive transistor when a parasitic capacitance of a light emitting element is charged by currents flowed through the drive transistor by the supply of the voltages, obtaining first and second current values of the drive current of the drive transistor based on the first and second voltage variations, obtaining characteristic values of the drive transistor based on the first and second measuring voltages and the first and second current values, and outputting a data signal based on the obtained characteristic values and a drive voltage of the drive transistor corresponding to the amount of emission of the light emitting element to the source terminal of the drive transistor.

An apparatus (100) and a method (200) for an accessory identifier for identifying a connected accessory type from three or more accessory types (102, 104, 106) are provided. Each of the three or more accessory types (102, 104, 106) has a unique identifier resistor (108, 110, 112), which is accessible through an identification pin (114, 116, 118) and is linearly related to each other in resistance value. Using a voltage source (120), presence of the connected accessory (102) is detected (204) by monitoring a voltage change at the source pin (126). Once the presence is detected, a predetermined current is sent through the source pin (126) and the resulting voltage at the source pin (126) is measured (208), and based upon the measured voltage, the connected accessory type (102) is identified (210).

A control strategy for distributed power generation modules in a power system that varies the line frequency or voltage according to a predetermined pattern to cause a PV inverter to modify its power output and thereby avoid overcharging a battery. When the power system operates in islanded mode, the AC load demand can be lower than the available energy from the PV array, causing the battery to become overcharged. To avoid this scenario, a hybrid inverter executes a pattern generator algorithm that varies the line frequency or voltage linearly, exponentially or any mathematical function or look-up tables. The PV inverter executes a pattern detection algorithm that detects the linear, exponential, or any mathematical function or look-up table change in the line frequency. In response, the PV inverter modifies its power output until an overcharging condition of the battery is removed. The line frequency/voltage can be varied within the anti-islanding limits to avoid premature disruption of the power system, and no additional settings are required at the device level in order to operate in any mode of operation: islanded, grid-connected or genset-connected.

A hybrid electric propulsion system for powering a vehicle using a natural fuel engine and an electric motor. The hybrid electric vehicle is comprised of a drive train; an electric motor for driving the drive train; an auxiliary power unit (APU); an electric energy storage system electrically coupled to the electric motor; and wherein the auxiliary power unit and the electric energy storage system provide energy for powering the vehicle. An electric bus is directly connected to both the auxiliary power unit and the electric energy source and the voltage across the electric bus is substantially the same as the voltage across the electric energy source so that a change in voltage of the electric bus results in the same change to the voltage across the electric energy source. A power management controller is programmed to control output power of the power unit to maintain the energy storage system between a predetermined high voltage set-point and a predetermined low voltage set-point.

In a battery pack manager that manages series-connected rechargeable unit cells, a cell equalizer equalizes the cell voltages by individually discharging the unit cells according to deviations from reference voltages. An overcharge/overdischarge detector detects an overcharge and an overdischarge state of each unit cell. An inhibit circuit prevents the cell equalizer from discharging the unit cells when the overcharge/overdischarge detector is activated to reduce the cell voltage variability, which would otherwise occur as a result of interference from the overcharge/overdischarge detector, so that the overcharge/overdischarge states of all unit cells can be determined with precision. Connecting lines of the unit cells are monitored to detect a line-cut. The inhibit circuit further inhibits the cell equalizer when the connecting lines are being monitored to reduce the cell voltage variability, which would otherwise occur as a result of interference from the line-cut detection, so that false line-cut detection is avoided.

A method and apparatus for locating integrated circuit defects associated with different aspects of the integrated circuit industry. The integrated circuit is configured in a known failing mode, with a first power supply providing a constant voltage and variable current. Next, one or more additional dedicated power supplies are connected to various points of interest throughout the integrated circuit, wherein these dedicated power supplies have a preset current and the voltage is allowed to vary. The integrated circuit is then scanned with a laser beam, which induces current changes on in the integrated circuit especially in defective areas. These current changes then cause voltage changes on the dedicated power supplies. When such a voltage change occurs on the dedicated power supplies, its position is noted.

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.

A light-emitting diode (LED) driving circuit and a secondary side controller for controlling the same control an output voltage of the LED driving circuit at a first driving voltage or a second driving voltage. When the output voltage is controlled at the first driving voltage, an LED module driven by the LED driving circuit is in a stably lighting state; and when the output voltage is controlled at the second driving voltage, the output voltage is approximately a threshold voltage of the LED module but higher than zero volt, so that the LED module is close to not emitting light. Therefore, in a dimming operation, the variation of voltage applied across the LED module is smaller than that in the conventional LED driving circuits to thereby protect the LED module against an excessive voltage stress and avoid the problem of inaccurate dimming.

An LED lamp includes a rectifier, an integrated circuit and a string of series-connected LEDs. The lamp receives an incoming AC signal such that a rectified version of the signal is present across the LED string. The integrated circuit includes a plurality of power switches. Each power switch is coupled so that it can separately and selectably short out a corresponding one of several groups of LEDs in the string. As the voltage across the string increases the integrated circuit controls the power switches such that the number of LEDs through which current flows increases, whereas as the voltage across the string decreases the integrated circuit controls the power switches such that the number of LEDs through which current flows decreases. LED string current flow is controlled and regulated to provide superior efficiency, reliability, anti-flicker, regulation against line voltage variations, power factor correction, and lamp over-voltage, over-current, and over-temperature protection.

Disclosed is a cell balancing apparatus and method using a voltage variation pattern of a battery cell, which measures voltage of each cell, estimates OCV or SOC of each cell using a voltage variation pattern of each cell including a present voltage and a past voltage, and eliminates a deviation in OCV or SOC between the cells through comparison of the estimated OCV or SOC of each cell. In estimating the OCV of each cell, an output voltage error due to IR drop is corrected. Thus, SOC of each cell may be accurately estimated. And, an accurate estimation of SOC may render substantial elimination for a SOC deviation of each cell. Furthermore, SOC estimating using an output voltage leads to an active cell balancing even during charge and discharge of battery, thereby minimizing an SOC deviation of each cell.

The rechargeable battery abnormality detection apparatus is provided with an internal short circuit detection section (20b) that monitors rechargeable battery (1) voltage change when no charging or discharging takes place, and detects internal short circuit abnormality when battery voltage drop during a predetermined time period exceeds a preset threshold voltage; a degradation appraisal section (20d) that judges the degree of rechargeable battery degradation; and a threshold control section (20c) that incrementally increases the threshold voltage according to the degree of degradation determined by the degradation appraisal section (20d).

A droop control system for grid-connected synchronization connects to a plurality of distributed power generation modules and a utility grid system. The droop control system includes a detection processing module and a plurality of regulation control modules corresponding to the distributed power generation modules. The detection processing module is coupled with the distributed power generation modules and utility grid system in parallel to obtain a voltage difference, a phase angle difference and a frequency difference. The regulation control modules perform droop control of real power-frequency variety and reactive power-voltage variety and phase angle compensation. Through reactive power-voltage variety droop control approach, impact of impedance alterations in the power system can be eliminated and voltage fluctuations can also be minimized to achieve stable effect. Hence electric power of the utility grid system and distributed power generation modules can be regulated synchronously.