187 results about "Electrical current" patented technology

A drive circuit is provided for an OLED pixel display. The drive circuit is adapted for use with a reference voltage source. It includes a first transistor and an OLED. The output circuit of the first transistor is operably connected between the reference voltage source and the OLED. Transmission gate means responsive to a control signal are provided to transmit a data signal to the first transistor. Means are provided for controlling the first transistor in accordance with a time domain modulation signal to provide an average current to the OLED which is a function of the data signal.

An instrument is disclosed for measuring resistivity of Earth formations from within a conductive pipe inside a wellbore drilled through the formations. The instrument includes a plurality of housings connected end to end and adapted to traverse the wellbore. At least one electrode is disposed on each housing. Each electrode is adapted to be placed in electrical contact with the inside of the pipe. The instrument includes a source of electrical current, a digital voltage measuring circuit and a switch. The switch is arranged to connect the source of electrical current between one of the electrodes and a current return at a selectable one of the top of the pipe and a location near the Earth's surface at a selected distance from the top of the pipe, and to connect selected pairs of the electrodes to the digital voltage measuring circuit. The pairs are selected to make voltage measurements corresponding to selected axial distances and selected lateral depths in the Earth formations.

The invention relates to a ground electrode circuit grounding protective system of a high-voltage DC transmission system. The system is provided with two parallel ground electrode circuits respectively connected in series with a high-voltage DC breaker, sets an allowable range of current differences of two ground wires and an allowable range of the subtraction of the line current sum of the two ground wires from the line current difference of the two ground wires and then sequentially executes the following control program: (1), reading currents of the two ground wires; (2), judging and comparing whether an absolute value of the current difference of two ground wires is larger than the allowable range thereof, if the absolute value is not larger than the allowable range, returning to the step (1); if the absolute value is larger than the allowable range, (3) then, judging whether the subtraction of the line current sum of the two ground wires from the line current difference of the two ground wires is smaller than or equal to the allowable range; if the subtraction is smaller than or equal to the allowable range, returning to the step (1); and if the subtraction is not smaller than or equal to the allowable range, enabling the high-voltage DC breaker which is connected in series with the ground wire with larger line current to trip and terminate the program. The system can avoid the imbalance of the ground electrode circuits due to the failures of the ground electrode circuits and protects the caused DC transmission system to be closed down.

An organic light emitting device includes a display panel which includes a plurality of pixels, a power supply which generates a driving voltage, an overcurrent detector which detects an overcurrent flowing from the power supply to the display panel, and a driving voltage blocking unit which blocks the driving voltage to the plurality of pixels based on an output signal of the overcurrent detector.

The following problem associated with a semiconductor device of silicon or the like having low band gap is solved by temperature estimation using voltage drop in such a semiconductor device having low accuracy and this complicates a circuit for temperature detection suitable for practical use or a configuration for implementing a detection system. A power converter provided with an inverter circuit includes a semiconductor device whose band gap is larger than that of silicon and which has a range in which the temperature coefficient of voltage drop during conduction is positive. The power converter further includes a measurement condition setting circuit. This circuit adjusts the timing of the following measurement values used for temperature estimation at a device temperature estimation circuit to each other so that a measurement value of a voltage measurement circuit and a measurement value of a current measurement circuit become data obtained by measurement at the same time.

A stent delivery and apposition detecting system includes at least one electrode pair of dissimilar metals mounted on a balloon of a balloon catheter. The electrode pair forms part of an electrochemical cell, and voltage and current generated from the electrochemical cell enables the system to detect when a stent mounted on the balloon achieves proper wall apposition. As the balloon is exposed to different environments, i.e., blood or tissue having different resistances, the electric potential of the electrochemical cell changes and an alert is generated by a feedback circuit to notify a user that the electrodes are in contact with tissue of the vessel wall. In one embodiment, the feedback circuit may be powered by the electrochemical cell. Multiple sets of electrode pairs may be mounted along the circumference and length of the balloon to detect differential contact between the deployed stent and the vessel wall.

A heat generating roller, fixing equipment and an image forming apparatus in which warm-up time is shortened while preventing excessive temperature rise and good fixing performance is realized by preventing occurrence of offset. In the heat generating roller, fixing equipment and image forming apparatus, the heat generating roller is formed principally by laying a high permeability conductive layer and a nonmagnetic conductive layer in layer. When a voltage is applied from a power supply (not shown) to an exciting coil and an AC current flow through it, magnetic flux is generated around the exciting coil and a magnetic field is formed. Since the heat generating roller has the high permeability conductive layer and the nonmagnetic conductive layer laid in layer, magnetic coupling of a system consisting of the heat generating roller and the exciting coil is good at the time of low temperature and heat generation of the heat generating roller is accelerated. When the Curie point is exceeded, skin depth becomes deep and skin resistance decreases, which suppresses generation of Joule's heat and reduces heat generation of the heat generating roller.

A closing phase that produces the smallest energization flux error at a connection input point is calculated based upon a residual flux of the first closing phase and the preliminarily given pre-arc characteristic and closing time deviation characteristic of a three-phase circuit breaker, so that the calculated phase value is set as a target closing phase of the first closing phase. A closing phase that produces the smallest energization flux error when a residual flux of zero is calculated, so that the calculated phase value is set as a target closing phase of the remaining two phases. The total time required from the reference point to the target closing phases of the remaining two phases and a delay time corresponding to an integer multiple of a given cycle of the three-phase power supply is set as a target closing time of the remaining two phases.

A modular motor controller family comprises a housing. Solid state switches are selected from one of plural switch sizes for controlling a desired voltage and current range. The switches are mounted in the housing for connection between an AC line and motor terminals for controlling application of AC power to the motor. A logic circuit board is mounted in the housing including logic circuitry for commanding operation of the solid state switches independent of the selected switch size. An interface circuit board selected from one of plural configurations is mounted in the housing and includes interface circuitry connected between the logic circuitry and the solid state switches. The interface circuitry is selected to interface with the selected switch size according to the desired voltage and current range.

The invention discloses an all-fiber current transformer and a method thereof, aiming to overcome the defects that a traditional electromagnetic current transformer is easily subjected to electromagnetic interference and has complicated insulation structure, magnetic saturation existence and the like. The technical scheme of the invention comprises the following steps of: demodulating light output by a light source into X-axis polarized light and Y-axis polarized light by a Y-branch integrated optical phase modulator; converting into sinistral circular polarized light and dextral circular polarized light in a lambda/4 retarder; generating a magnetic field by a current in a lead due to the faraday effect; returning the two beams carrying faraday effect phase information to the Y-branch integrated optical phase modulator to intervene when beams in optical fiber is transmitted around the lead; and enabling an interference result to enter a subsequent treatment system from the optical fiber coupler to acquire the faraday effect phase information at the measuring point. The invention avoids the hidden danger of ferromagnetic resonance and magnetic saturation by adopting the optical fiber as a sensing medium and has a series of advantages of high detection accuracy, good environmental suitability, and the like.

A phase change memory device includes a memory cell having a phase change material, a write driver which supplies a step-down set current to the memory cell, where the step-down set current includes a plurality of successive steps of decreasing current magnitude, and a set program control circuit which controls a duration of the step-down set current supplied by the write driver.

The invention relates to a smooth switching control method for an operating mode of a micro-grid inverter of different capacity micro sources. The method is applied to a micro-grid consisting of multiple different capacity micro sources. The method comprises the following steps: by virtue of switching among different switches, realizing smooth switching of an inverter control method under island/grid-connected operating modes, wherein the island operation is controlled by robust V-f based on capacitive equivalent output impedance so as to generate the voltage reference quantity, and the grid-connected operation is controlled by adopting PQ; adding a pre-synchronization link to be used for controlling the inverter output voltage to trace the power grid voltage when the inverter is switched from island operation to the grid-connected operation, and ensuring that the grid-connected operation is smoothly finished; introducing virtual impedance, designing the equivalent output impedance of the inverter to be capacitive, reducing loop current between parallel inverters, and well realizing power distribution among different capacity micro sources; and adopting double-loop control of the outer voltage loop and inner current loop, wherein the outer voltage loop is controlled by PI, and the inner current loop is controlled by dead beat. Therefore, the system is high in stability and high in dynamic response speed.

A switching constant-current power device can stabilize current flowing to a load (e.g. a display device comprising an LED, or the like) even when the current is repeatedly interrupted. A voltage current detector is connected to the output side of a power converter and creates a voltage signal in accordance with the output voltage thereof; and a feedback circuit is provided between a controller for driving the power converter and a current detector, which generates a first feedback signal in accordance with the load current. The feedback circuit comprises a signal holding unit, which outputs a second feedback signal that was created by consulting the voltage signal at a given time, the feedback circuit supplying the first feedback signal, output by the current detector, to the controller when load current is flowing, and supplying the second feedback signal, output by the signal holding unit, to the controller when load current is not flowing.

The invention discloses a storage battery detector and a vehicle-mounted network system for an intelligent automobile. The storage battery detector of the intelligent automobile comprises an input terminal, a current sensor, a temperature sensor, a charging and discharging current detection circuit, a voltage detection circuit, a temperature detection circuit, a microprocessor and a bus communication module, wherein the input terminal is partitioned into two paths; one path is connected with the current sensor; the current sensor is connected with the charging and discharging current detection circuit; the other path is connected with the voltage detection circuit; the temperature sensor is connected with the temperature detection circuit; the charging and discharging current detection circuit, the voltage detection circuit and the temperature detection circuit are connected with the microprocessor; and the microprocessor is connected with the bus communication module. The storage battery detector for the intelligent automobile is used for monitoring the insufficient voltage status of a storage battery, the charging status health condition and the like, and can be connected to the vehicle-mounted network system for protecting the insufficient voltage status of the storage battery, so that the service life of the storage battery is prolonged.

A multi-winding high step-up DC-DC converter includes a three-winding transformer to transform a low DC voltage to a high DC voltage; a power switch to control the energy flux of the primary winding of the three-winding transformer based on turning on/off the power switch; a first diode to control the current of the first secondary winding of the three-winding transformer; a second diode to control the current of the second secondary winding of the three-winding transformer; and a third diode to control the current of the primary winding. When the DC-DC converter is in the first operation state, the switch and the second diode are in on state, and the first and the third diodes are in off state. When the DC-DC converter is in the second operation state, the switch and the second diode are in off state, and the first and the third diodes are in on state.

The invention relates to a stirring device for a soil body improvement test in the construction of a soil pressure balance shield. The stirring device can be used for an indoor stirring test for testing the frictional property and the stirring torque of a soil body. The device is characterized in that a beam is arranged above a frame-shaped bracket, and a motor, a motor transmission and an ampere meter are arranged on the beam; stirring buckets are fixed on a base, the base is arranged on the frame-shaped bracket, and stirring blades are arranged in each stirring bucket and connected with an output shaft of the motor through a rotating shaft; a series of fixing devices on which stirring buckets in different sizes can be arranged is arranged on the base, and the fixing devices can lift and horizontally slide through a lifting frame at the bottom of the bracket and a base rail; and a computer is connected with the ampere meter so as to record the change process of the motor current along with the time during the stirring process in real time. The invention is used for the indoor stirring test for testing the frictional property and the stirring torque of the soil body, is suitable for a plurality of soil layers and has the advantages of simple and convenient test procedure, real-time current change recording and favorable testing effect.

The invention discloses a chopper-type direct current detection method and a circuit. A forward voltage and a backward voltage of two ends of a shunt resistor are continuously collected in real time through a certain frequency. A sampling value of a first half of a chopper period and a sampling value of a second half of the chopper period in a same chopper period are calculated and influences of a low-frequency noise, an offset voltage and other noises on a detection result are eliminated. The detection circuit comprises a shunt resistor, a simulation switch, an amplifier, an analog-to-digital converter and a control unit. The simulation switch is connected in parallel to two ends of the shunt resistor. An input terminal of the amplifier is connected to an output terminal of the simulation switch. An input terminal of the analog-to-digital converter is connected to an output terminal of the amplifier. An input terminal of the control unit is connected to an output terminal of the analog-to-digital converter. An output terminal of the control unit is connected to a control signal input terminal of the simulation switch. On one hand, the control unit provides a digital signal to control switching of the simulation switch; on the other hand, according to digital forward and backward voltage signal, the control unit acquires a direct current detection value. A circuit structure provided in the invention is simple; test accuracy is high and cost is low.

An electric vehicle includes a control unit having overcurrent generation judgment unit, inverter selection unit, and inverter drive control unit. The overcurrent generation judgment unit judges whether an overcurrent is generated in an inverter for generation or an inverter for travel. When an overcurrent is generated in one of the inverters, the inverter selection unit selects the other inverter to be driven. The inverter drive control unit stops the driving of the one inverter and drives the other inverter to drive a travel motor or a generator.

An improved heating system air pressure sensing port. An example aircraft pitot tube heater uses Positive Temperature Coefficient (PTC) switching thermistors arranged to automatically sense the outside air temperature and heat to a design set point temperature. When a high outside air temperature is experienced, the pitot tube will not turn on. The pitot tube heater only turns on below the design set point and will consumes less current than the standard aircraft pitot tube heaters when operating at very cold temperatures. Virtually no current is drawn when the pitot tube increases past the set point, thus reducing the power drain on the aircraft system. The use of multiple thermistors gives the example pitot tube a level of failure redundancy that is not available in current pitot tube heaters.

The invention discloses an intelligent monitoring device for temperature and insulation state of a 330KV high-voltage cable in a hydropower station. The device is characterized by being provided with a central processing module unit (CPU), a data acquisition and conversion unit, a light transmitting/receiving module, an alarm output module, a plurality of optical fiber temperature sensors and a plurality of current sensors, wherein the data acquisition and conversion unit is used for transmitting digital signals to the CPU under the control of the CPU; the light transmitting/receiving module is used for transmitting electrical signals to the data acquisition and conversion unit; the alarm output module can be used for communication with a remote monitoring system; the optical fiber temperature sensors are respectively arranged at the joints of the high-voltage cable to be detected and used for connecting temperature detection signals to the light transmitting/receiving module; and thecurrent sensors are respectively arranged on joint metal sheaths of the high-voltage cable to be detected and used for connecting current detection signals to the data acquisition and conversion unit. The device is particularly suitable for safety monitoring of the 330KV high-voltage cable in the hydropower station, can realize real-time monitoring of the temperature and the insulation state of the cable in the hydropower station, and can also ensure self safety.

The invention discloses a current generating circuit with an adjustable temperature coefficient. The current generating circuit comprises a current mirror, an operational amplifier, a switching tube,at least two positive temperature coefficient resistors, at least two negative temperature coefficient resistors, a positive temperature coefficient switch and a negative temperature coefficient switch. Thus, on the basis of a voltage-to-current circuit in the prior art, output current is appropriately matched, the current generating circuit achieves the adjustable temperature coefficient, resistance matching is different from traditional pure serial connection or pure parallel connection, and circuit space is saved; the accuracy of the temperature coefficient is high.

The invention discloses a neutral point direct current online measurement device for a transformer, which comprises a Hall sensor, a copper bar, a transmission fiber, a signal processing module arranged in a box body, a photoelectric power conversion module, a measurement signal photoelectric conversion module and a power laser launching circuit module, wherein the copper bar penetrates through the two sides of the box body; the copper bar in the box body is sleeved with the Hall sensor; the signal processing module is used for receiving an output signal of the Hall sensor, converting the output signal into an optical signal and outputting the optical signal into the measurement signal photoelectric conversion module; the measurement signal photoelectric conversion module is used for converting the inputted optical signal into an electrical signal to output; the photoelectric power conversion module is used for providing power for the Hal sensor and the signal processing module; and the power laser launching circuit module is used for inputting medium power laser for the photoelectric power conversion module. The neutral point direct current online measurement device adopts the optical fiber to supply the energy and transmit the signals, blocks an over-voltage transmission path and improves the measurement stability and the accuracy.

Certain aspects of a method and system for a process sensor to compensate SoC parameters in the presence of IC process manufacturing variations are disclosed. Aspects of one method may include determining an amount of process variation associated with at least one transistor within a single integrated circuit. The determined amount of process variation may be compensated by utilizing a process dependent current, a bandgap current, and a current associated with a present temperature of the transistor. The process dependent current, the bandgap current and the current associated with the present temperature of the transistor may be combined to generate an output current. A voltage generated across a variable resistor may be determined based on the generated output current.