86results 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 provides a switching mode power source which comprises a rectification filter (1), a controller (2), a switching tube (3) and a transformer (4), wherein a primary coil (41) of the transformer (4) is connected to one end of the switching tube (3), the other end of the switching tube (3) is connected to the current detection end of the controller (2), the output end of the rectification filter (1) is connected to the power source input end of the controller (2), and the drive waveform output end of the controller (2) is connected to the control end of the switching tube (3). The controller (2) is used for outputting a drive waveform according to the input feedback voltage to control the on-off of the switching tube (3) so as to stabilize voltage or current which is output by asecondary coil (42). An auxiliary coil (43) of the transformer (4) is connected to the voltage input end of the controller (2) to input feedback voltage. Because a method of feeding back voltage fromthe auxiliary coil is adopted, the switching mode power source provided by the invention has the advantages of simple circuit and good loop stability.

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 discloses a light-emitting diode (LED) lamp controller based on a digital pulse-width modulation (PWM) control technology. The LED lamp controller comprises a power management module, a direct current-direct current (DC-DC) convertor, a constant current control circuit which corresponds to one or more sets of LED lamp strings one to one, and a control module, wherein the input end of the power management module receives a power voltage signal input from the outside; the control module receives a PWM signal input from the outside; the input end of the DC-DC convertor is electrically connected with the output end of the power management module; the output end of the DC-DC convertor is electrically connected with one end of the one set of LED lamp string or of each of the multiple sets of LED lamp strings; the control module is electrically connected with the control end of the DC-DC convertor and the input end of the constant current control circuit; and the output end of the constant current control circuit is electrically connected with the other end of the one set of LED lamp string or of each of the multiple sets of LED lamp strings. A combined circuit formed by basic components is used for controlling a signal set of LED lamp string, and multiple sets of LED lamp strings which are parallelly connected with one another; and the LED lamp controller has the characteristics of low cost and flexile control.

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 invention discloses a fully automatic current online detection and automatic calibration circuit of multiple charge and discharge channels. The fully automatic current online detection and automatic calibration circuit comprises a current detection module, a current sampling module, a channel switching module, a calibration control module and a charge and discharge control module. The currentdetection module, the channel switching module and the charge and discharge control module are internally and separately provided with a current detection unit, a channel switching unit and a charge and discharge control unit in one to one correspondence to the charge and discharge channels, the input ends of the current detection unit are arranged in the corresponding charge and discharge channels in series, the input end of the channel switching unit and the output end of the current detection unit are connected in a one-to one corresponding mode, and the output end of the channel switchingmodule is connected with the input end of the current sampling module. The current sampling module is connected with the calibration control module through communication, and the calibration control module is connected with the charge and discharge control module through communication. The fully automatic current online detection and automatic calibration circuit of the multiple charge and discharge channels can well solve the problem of battery performance difference caused by inconsistent current of the charge and discharge channels in the production process of batteries.

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 present invention relates to a current accuracy calibration method for a failure indicator production link. Compared with the prior art, the defect that the current accuracy can not be improved by the calibration method of a fault indicator is solved. The method comprises a verification mode of calibrating the current accuracy in a verification mode and a normal mode of calculating a routine calibration coefficient in a normal mode. According to the current accuracy calibration method, the failure indicator calibration process is optimized, and the accuracy of line load current sampling is 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.

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 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 an intelligent fuse test system. The intelligent fuse test system includes a test and control center module, a time-current device module and a high-pressure jet fuse module; the test and control center module includes a computer, a printer and a USB-RS485 converter; the time-current device module includes a constant current source, a current detection device, a hardware timer and a current transformer; and the high-pressure jet fuse module comprises a high-pressure jet fuse holder, a contactor, a bracket and a current line, wherein current line is used for replacing a fuse in the high-pressure jet fuse holder so as to simulate the fusing state of the fuse when the contactor is switched off under control. When current exists in the system, the current detection device detects the current, the timer is triggered to carry out timing through a line 1; and after the fuse is fused, the current detection device cannot detect the current, the timer is triggered to stop timing through a line 2. The intelligent fuse test system of the present invention is not affected by the magnitude and fluctuation of the current and is simple and reliable. With the intelligent fuse test system adopted, time from a time point when test current is loaded to the fuse to a time point when the fuse is fused can be obtained accurately, and whether the fuse is qualified is judged.

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 discloses a high-efficiency control method for a permanent magnet synchronous motor. The high-efficiency control method comprises the step of: screening a low-speed MTPA (maximum torquecurrent ratio) working point, i.e., a first working region working point, through using a motor parameter correlation formula; acquiring a group of high-speed weak magnetic voltage limit elliptical working points through bench testing; importing data obtained by bench testing into MATLAB, and fitting rest working points of the second working region by utilizing a data fitting toolbox of the MATLAB; merging all the obtained points into a table by taking a stator phase voltage peak value as a boundary; and querying the generated table according to the given moment and the feedback speed to directly obtain the optimal working current in the current state. By adopting the high-efficiency control method, the table data is few, and the occupied storage space is small; and motor operation regionsare separately processed, and current compensation is performed in a weak magnetic voltage limit oval region so that control is enabled to be more comprehensive and accurate.

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.

The invention discloses a multi-channel current collecting system with a wide temperature range and high precision, which mainly comprises a casing, a power input socket, an output socket, a relay, nsensing modules, a control circuit board, and a front panel. The power input socket is connected with a power supply. The current of the power supply flows through the relay, n sensing modules, and then is output to an external device through the output socket. The output socket is connected to n external devices. The Hall sensor respectively measures the induced voltage values of the current operating currents of the n external devices and sends them to the control circuit board. The temperature sensor measures the temperature value of the Hall sensor and sends it to the control circuit board. The control circuit board calculates the current value of the external device based on the received temperature value and voltage value. The system uses a temperature sensor, an integrated Hall current collector, and a high-precision A / D converter to achieve a processing system that has a current accuracy of 0.1A and simultaneously detects multiple devices in a wide temperature range of -40 DEGC to +55 DEG C.