1656 results about "Current amplitude" patented technology

Exemplary embodiments provide a system, method and apparatus for regulating current in loads, such as in an array of independent pluralities of light emitting diodes (“LEDs”). An exemplary system comprises a multiplexer adapted to switch current to each independent string of LEDs; a first controller to maintain a substantially constant average current level to the plurality of LEDs; and a second controller to modulate a current amplitude and duration of time division multiplexing for each independent string of LEDs. Another aspect of the system provides for modulating the on time for switching current to maintain a substantially constant average current level and to respond and converge quickly to changing current reference levels.

A portable DC power manager (400) includes an internal power bus (410) and a plurality of device ports (1150, 1160, 1170, 1180, 1190, 1200) for connecting with external power and energy sources, external power loads and other external power managers. Each device port is isolated for the internal power bus by controllable switches (A, B, C, D). Power converters (440, 442, 510) may be disposed between device ports and the internal power bus to convert voltages and attenuate current amplitude. Energy management schema operating on the power manager sums available power and allocates the available power to connected power loads according to power priority settings. A hot-change-over circuit (1300) connects additional sources to the internal bus in response to a voltage drop on the internal power bus. A compact and lightweight package (1100) enables a portability.

In a drive system of an AC motor in which a motor current is feedback-controlled, a motor current command is produced in a normal operation according to a torque command value on an optimum efficiency characteristic line so as to select an optimum current phase maximizing an output torque with a constant motor current amplitude. Conversely, when the AC motor produces an excessively generated power exceeding a regeneratable power quantity of the AC motor, a consuming operation is performed for intentionally increasing the power loss in the AC motor. In the consuming operation, the motor current command is produced according to the torque command value on a loss increase characteristic line to change the current phase from the above optimum value. Thereby, the power loss in the AC motor can be increased to consume the surplus power without causing instability in the motor control.

The invention relates to a grid thunder-threat distribution confirming method. The confirming method adopts a computer to process thunder automatic monitoring data and establish a databank, and adopts a grid method to carry out statistical analysis to the thunder parameter while taking a geographic information system and the databank as an analysis platform, and then adopts the computer to carry out the statistical analysis to the thunder data according to typical criterion so as to obtain the thunder-threat distribution of corresponding objects. The method has the following basic steps: firstly, the thunder automatic monitoring data is stored in the databank by the computer; then grid distribution is carried out to selected zones on a digital map; the data of each grid is analyzed statistically to obtain the statistical thunder parameter; and then the current-amplitude value of threatening thunders which can cause the flashover of insulator strings of power transmission lines is adopted as judging evidence according to a grid insulation structure to make the statistical analysis to the attribute of the thunder current-amplitude value and eliminate the useless data; special attribute data of happened flashover accidents caused lightning-strike on the power transmission lines is stored in the computer; finally, the computer is used for figuring out corresponding geographic distribution layers so as to obtain the grid electronic thunder-threat distribution chart. The method has the advantages that the method is easy and intelligible with better operability and practicability.

A method and apparatus for controlling a welding-type power supply includes providing a current wave form having an arc current portion and a short circuit current portion. An arc state is entered by retracting a welding wire, and a short circuit state is entered by advancing the wire. The current enters the arc current portion prior to the creation of the arc and the current enters the short circuit current portion prior to the creation of the short, by coordinating the wave form with the wire retraction. This may be preformed on a wire having a diameter of 2.4 mm or more to a weld and applying a welding current of less than 100 amps, or of less than 35 amps. One current waveform during the arc state includes at least three segments, and the last segment is entered into prior to the short circuit state being entered, and is the same current magnitude as the current magnitude at the start of the short circuit state. Penetration and / or bead formation may be controlled by controlling the advancement of the wire into the weld pool. The balance may be user set.