85results about How to "High current accuracy" patented technology

In an active matrix EL display device, pixels which are suitable for a constant current drive are structured. The pixel includes a first switch which has one end connected to a source signal line and the other end connected to a current-voltage conversion element, a second switch which has one end connected to the current-voltage conversion element and the other end connected to a voltage holding capacitor and to a voltage-current conversion element, and a pixel electrode connected to the current-voltage conversion element and to the voltage-current conversion element.

The invention discloses a light-emitting diode (LED) driver for illumination. The LED driver for the illumination comprises an alternating current (AC)/direct current (DC) module and a constant current control module, wherein the AC/DC module adopts an LLC resonant conversion topological structure, and is used for converting alternating current commercial power into direct current; and the constant current control module is connected with the AC/DC module and used for outputting constant current by taking low-voltage direct current as driving voltage to drive an LED light source by the constant current. The LED driver for the illumination can realize the constant current driving of LEDs for the illumination, and simultaneously ensures the safety and reliability of the LEDs.

The invention relates to a current sampling Hall sensor device, comprising a magnetizer (1) and an Hall sensor (2), wherein, the magnetizer (1) is in a ring shape with an opening; the Hall sensor (2)is positioned in the opening and comprises a plurality of Hall chips (4) which have different measuring ranges and are connection with each other in parallel. The device of the invention can ensure the ranges of current sampling and can improve the accuracy of current sampling.

An apparatus corrects a current value of a three-phase electric motor including a current detector that detects current of each of three phases including a first phase, a second phase, and a third phase. The apparatus includes a current-value correcting unit. When current of one of the first to third phase is zero-crossing, the current-value correcting unit corrects a current value of at least one of the others of the first to third phases on a basis of a correlation between detection values of the current detectors provided for the others of the first to third phases during a period in which the three-phase electric motor is operating.

The invention relates to a method for controlling currents of an X ray tube and a device for controlling the currents of the X ray tube by implementing the control method. In the method and the device, an analog option switch gates a filament current sampling unit or a tube current sampling unit and feeds back to a gain control unit, so that two closed-loop gain control loops are formed. Time-shared control is performed on the two closed-loop gain control loops, namely time-shared gain control is performed on filament currents and tube currents. Therefore, multiple-loop time-shared control can be performed on the currents of the X ray tube, the filament currents can be rapidly improved into currents required by proximity exposure, and more precise tube currents can be obtained after normal work, so that the X ray tube is practical and convenient and has high stability.

A phase reference generator for use in a resistance weld control. The phase reference generator including a digital signal processor having a digital volt-time area generator to generate a volt-time area of an observed voltage; a digital current-time area and current-difference-time area generator to generate a current-time area of an observed current and a current-difference-time area of the observed current; a line impedance estimator; and, a driving point voltage area estimator configured to receive values from the digital volt-time area generator, the digital current-time area generator and current-difference-time area generator, and the line impedance estimator and generate estimates of the driving point voltage.

The invention provides a dead-beat current control method for a permanent magnet synchronous servo motor. The method comprises the following steps: (S1) current estimation; (S2) current estimation-based reference voltage calculation; and (S3) rotor motion compensation. The dead-beat current control method has the beneficial effects that a topology of which the other controls can promote mutually in a dead-beat current control and a vector control and the performance and the stability are relatively high is provided by fully considering the characteristics of the vector control and the characteristics of the permanent magnet synchronous servo motor; and the vector control-based potential of the permanent magnet synchronous servo motor is fully developed.

A control apparatus for a four-wheel drive vehicle includes a current detector configured to output a detection signal in accordance with the magnitude of an actual control current, a target current value calculator configured to calculate a target current value that is a target value of the control current, and a current controller configured to control a current output circuit to output the control current having the target current value calculated by the target current value calculator based on a result of detection performed by the current detector. When the four-wheel drive vehicle is in a two-wheel drive mode in which first and second friction clutches are released, the current controller performs zero-point adjustment for adjusting a zero point of the control current to be output from the current output circuit.

An object is to ensure torque accuracy by suppressing the occurrence of low-frequency fold-back noise caused by aliasing, and stable control performance with respect to environmental variations, such as angular errors, power voltage ripples, and so on.

A motor control device includes a current detector (10) which, in generating a feedback current value on the basis of the detection result of a three-phase AC current supplied from an inverter (2) to a motor (1), generates a first current detection value based on a first sample timing and a second current detection value based on a second sample timing that is shorter than the first sample timing; a coordinates converter (11) which converts the coordinates of the first current detection value and the second current detection value to q and d axes; and a detection current processor (13) which generates a feedback current value from the coordinate conversion results.

Methods and systems are disclosed that may be employed to enable multi-phase voltage regulator (VR) system calibration during the development phase of a multi-phase VR system so as to meet defined accuracy targets and, in one example, to avoid the need for system level calibration in a production environment. The disclosed systems and methods may be further implemented to enable use of multiple sources for and types of integrated power stages (IPstages) in a common multi-phase VR system configuration while still achieving the required current sense accuracy, thus reducing or substantially eliminating continuity of supply (COS) concerns. The disclosed methods and systems may also be implemented to improve accuracy of current sense in a manner that improves VR system performance, power saving and reliability.

The invention discloses a dimming control method, a dimming control circuit and a power converter applying the dimming control method and the dimming control circuit. According to the technical schemeof the embodiment of the invention, the length of a switching period of a power converter is adjusted through a dimming signal, the on-off state of a power switch of a power circuit is controlled according to an output signal of the power converter, or the on-off state of the power switch is controlled according to the dimming signal; and the problem of poor output current precision caused by thelimited response time of an amplifier in a circuit system, the nonlinear relationship between a current reference signal and a dimming signal and the like when a dimming signal set value is small isavoided, the current precision is improved, combined dimming is achieved to improve the dimming depth, and the dimming range is widened.

The disclosure relates to a turnout fault early warning method and device. The method comprises the steps that first current information of an electric switch machine in the current state is acquiredthrough a current acquisition assembly; the working state of a turnout is determined according to the first current information of the electric switch machine, wherein the working state of the turnoutcomprises a normal state or an abnormal state; and when the working state of the turnout is determined to be an abnormal state, alarm prompting is conducted in a preset mode. Therefore, an abnormal problem of the turnout can be found in time according to the current condition of the electric switch machine, accurate data can be provided for turnout maintenance, and a reliable basis can also be provided for positioning of the maintenance problem, so taht the railway operation and maintenance efficiency can be effectively improved.

The invention provides a system for charging and discharge of a battery pack. The charge and discharge system comprises a current generating circuit unit having multiple current generating circuits for receiving power and generating currents; a power transmission unit distributing power input during a charging process, transmitting the distributed power to the multiple current generating circuits and transmitting currents supplied to the mulitple current generating circuits during a discharging process to a power supply unit; a first current sensing circuit unit sensing currents output from the multiple current generating circuits; a second current sensing circuit unit sensing the total currents outputs by the current generating circuit unit; a current control circuit unit comparing the current sensed by the first current sensing circuit unit and the current sensed by the second current sensing circuit unit and controlling each current generating circuit so as to keep a current balance among the current generating circuits.

The invention relates to a wireless charging receiving end, a terminal and a wireless charging method. The wireless charging receiving end comprises an energy receiver, a receiving end chip, a charging management module and a constant current control device, wherein the receiving end chip converts alternating current into direct current and modulates and demodulates a wireless signal, the chargingmanagement module outputs the output current and the target current of the charging management module to the constant current control device, and in the constant current charging stage, the constantcurrent control device adjusts the output voltage of the charging management module according to the output current and the target current, so that the charging management module performs constant current output according to the target current. According to the invention, the reliability and stability of the output voltage of the wireless charging receiving end can be ensured, and the response speed of current control is high; the stepping of voltage regulation can reach 20 mV, and the current precision is improved; and the whole charging process is stable and is not influenced by load fluctuation of the terminal system, so that the user experience and the charging safety are improved.

The invention discloses a low-temperature coefficient boosting circuit with adjustable amplitude. The low-temperature coefficient boosting circuit comprises an operational amplifier, a mirror image circuit containing an operational amplifier negative feedback loop, a sampling resistor, a boosting resistor and an enabling switch; the inverting input end of the operational amplifier is used for inputting reference voltage, and the same-phase input end of the operational amplifier is connected with the sampling resistor and then is grounded; the input end of the mirror image circuit is connectedwith the output end of the operational amplifier, the first output end of the mirror image circuit is connected with the sampling resistor and then is grounded, and the second output end of the mirrorimage circuit is connected with the boosting resistor after passing through the enabling switch; the negative feedback loop of the operational amplifier is used for enabling the voltage between the mirror image circuit and the sampling resistor to be equal to the reference voltage; and a voltage output end is arranged between the enabling switch and the boosting resistor, and the sampling resistor and the boosting resistor are the same in type. The low-temperature coefficient boosting circuit has the characteristics of being adjustable in amplitude, low in temperature coefficient and precision and the like.

A current detection device includes: a core to be disposed in the vicinity of a conductor as a detection target; a winding wound around the core; an excitation unit configured to apply an excitation signal, having a magnitude and a direction that change at a constant period, to the winding; a magnetic flux detection unit (comparator and averaging circuit) configured to detect a magnetic flux generated in the core due to current flowing through the conductor; and an adder unit configured to add a feedback signal to the excitation signal such that the magnetic flux detected by the magnetic flux detection unit is cancelled.

A current detecting circuit includes: a shunt resistor; an amplifier; a first signal line connecting a first terminal of the shunt resistor to a first input terminal of the amplifier; a second signal line connecting a second terminal of the shunt resistor to a second input terminal of the amplifier; and a third signal line connecting the second terminal of the shunt resistor to a first power supply terminal of the amplifier.

The invention relates to a constant current source circuit which comprises a main circuit. The main circuit comprises a first three-end stabilizer, a transistor, a sampling resistor and a load, wherein an output end of the first three-end stabilizer is connected with a control electrode of the transistor, a reference electrode of the transistor is connected with a voltage input end, a working electrode is connected with one end of the load, the other end of the load is connected with one end of the sampling resistor, and the other end of the sampling resistor and an input end of the first three-end stabilizer are respectively connected with a reference potential. The constant current source circuit is characterized by further comprising an adjusting unit which comprises a voltage stabilizing unit, a fourth resistor and a fifth resistor. The voltage stabilizing unit generates second reference voltage larger than first reference voltage generated by the first three-end stabilizer and provides the second reference voltage to an adjusting end of the first three-end stabilizer through the fourth resistor, and the fifth resistor is connected between a node between the load and the sampling resistor and the adjusting end of the first three-end stabilizer. The constant current source circuit has the advantages of being high in efficiency, high in current accuracy and good in temperature excursion performance. The invention further relates to a sampling circuit.

The invention provides an LED drive circuit and method. The LED drive circuit comprises: a voltage reduction module; a peak value control module which is used for outputting a turn-off control signalwhen the current flowing through the LED lamp section reaches a set peak value; a turn-off time control module which is used for adjusting the turn-off time of the power switch tube; and a driving control module which is used for generating a driving signal based on output signals of the peak value control module and the turn-off time control module. The power switch tube is controlled by adoptingfixed peak turn-off; and when the output current is small, the turn-off time is shortened, and when the output current is large, the turn-off time is prolonged, and the turn-off time of the power switch tube is self-adaptively adjustable. Fixed peak current turn-off is adopted, overshoot is avoided during output in loop control, and rapid starting can be achieved; after average current detection,the output current precision is high, the turn-off time is adjusted internally, external setting is not needed, external pins and elements can be reduced, and the system cost is reduced; and LED ripple current is internally fixed and is not influenced by external conditions and element parameters.