Showing papers on "Current sensor published in 2003"

Fault detection and fault tolerant control of interior permanent magnet motor drive system for electric vehicle

Abstract: This work presents a control strategy that provides fault tolerance to the major sensor faults which may occur in an interior-permanent-magnet-motor (IPMM)-based electric vehicle propulsion drive system Failures of a position sensor, a dc-link voltage sensor, and current sensors are all included in the study assuming no multiple faults For each possible sensor fault, a corresponding method of detection or diagnosis is provided Additionally, once the fault is detected, the control scheme is automatically reconfigured to provide post-fault operational capability A state observer is used to provide missing current information in the case of current sensor faults Experimental results demonstrate the effectiveness of both the fault detection algorithm and the reconfigurable control scheme The resulting IPMM drive system proves to be resilient to sensor failures while providing smooth transition to the post-fault operational mode

An overview of integratable current sensor technologies

Abstract: An overview is given of current sensing technologies that are suitable for packaging into integrated power electronics modules and integrated passive power processing units, such as integrated shunts and integratable Rogowski coils technologies. Technologies considered in this paper include: integrated current shunts, current transformers, Rogowski coils, Hall-effect current sensors, giant magneto resistive sensors (GMR) and magneto impedance sensors (MI). Each of these current sensing technologies is discussed separately along with their advantages, limitations and design trade-offs. Special emphasis is given to features that enhance or limit the technology's potential for being integrated in the packaging process.

Integrated current sensor

Abstract: An integrated current sensor includes a magnetic field transducer such as a Hall effect sensor, a magnetic core, and an electrical conductor The conductor includes features for receiving portions of the Hall effect sensor and the core and the elements are dimensioned such that little or no relative movement among the elements is possible

Closed loop current control circuit and method thereof

Abstract: A circuit and method for providing closed loop control using constant current switching techniques is disclosed herein. By controlling the current supplied to high intensity light emitting diodes (LEDs) using the techniques and circuits described, high intensity LEDs can be operated at or near their maximum capacity without danger of overloading the LEDs, and without using excess amounts of current. A circuit as described herein, has multiple high side switches, each of which is connected to an LED array. The LED arrays are in turn connected through an inductor to a current switching control section that switches current to ground, or recirculates the current to maintain LED current flow within a desired range.

Current drive circuit and drive method thereof, and electroluminescent display apparatus using the circuit

Abstract: A current drive apparatus for an active matrix display operates a plurality of loads, e.g. organic or inorganic EL elements, by applying a current thereto. The apparatus includes a plurality of output terminals to which the loads are respectively connected. A single current generation circuit comprising e.g. a digital to analogue converter and a current mirror, outputs an operating current having a predetermined current value. A plurality of current storage circuits are provided in accordance with the respective output terminals, sequentially sample and hold the operating current and then simultaneously output the drive currents based on the sampled operating currents to the respective output terminals. The operating current has a current value according to an input signal. The current storage circuit includes a voltage component holding section which samples the operating current outputted from the current generation circuit and holds a voltage component for driving a drive control current corresponding to a current value of the operating current for driving a second current mirror.

Driving device, display apparatus using the same, and driving method therefor

Abstract: A driving device which supplies a current to a plurality of current?driven optical elements (Ep) to drive the optical elements includes at least a driving current supply circuit (133) which supplies a driving current to each optical element for a predetermined period, and a control voltage applying circuit (132) which applies a charge voltage having a voltage value corresponding to a voltage to be applied to each optical element using the driving current, before the driving current is supplied. The driving current supply circuit (133) includes a single constant current generating circuit (10A, 10B, 10C) which outputs a constant current having the same current value as that of a driving current, and a plurality of current storage circuits (30A, 30B, 30C) which sequentially receive and hold the constant current and output the driving current on the basis of the constant current.

Battery state-of-charge estimator

Abstract: A battery ECU estimates the SOC by integrating the battery current measured by a current sensor, and the battery voltage Vn is measured by a voltage sensor and the battery temperature Tn is measured by a thermometer if the fluctuation of the charging/discharging current is great (S204). If the number m of estimations of SOCn is m<10, m is incremented (S208). The battery internal resistance Rn is estimated from the measured battery temperature Tn by using a correlation map showing the correlation between the previously stored battery temperature T and the battery internal resistance R (S210). An estimation charging/discharging current In is determined using the measured battery voltage Vn, the battery open voltage Vocvn-1 determined on the basis of the previously estimated charged state, and the estimated battery internal resistance Rn (S212). The SOCn is estimated by integrating the estimated charging/discharging current In (S214). If the number m of estimations of the SOCn is m=10 (S206), the number m of estimations is changed to 0 (S220). The charging/discharging current in is measured by a current sensor (S222). The battery internal resistance Rn is calculated from the battery voltage Vn and the charging/discharging current in (S224). The battery temperature Tn is also measured, and the T-R correlation map is corrected (S226).

Drive circuit, display apparatus, and information display apparatus

Abstract: The present invention relates to a configuration utilizing a driven element that is driven by a current Specifically, there is provided a pixel circuit having a driven element and a current-drive transistor for supplying a current for driving the driven element to a current injection terminal of the driven element, a voltage buffer, a current signal line for supplying a current signal to the pixel circuit, and a wiring for connecting an output of the voltage buffer and a gate electrode of the current drive transistor The pixel circuit has a switch for controlling connection between the voltage buffer and the gate electrode of the current-drive transistor, and an input terminal of the voltage buffer is connected to the current signal line

Direct current control-a new current regulation principle

Abstract: In this paper, two novel methods for current regulation are proposed. Both methods follow the synchronized on-off principle. In the classical approach, transistors are switched depending on the sign of the current error, which in turn is sampled at equal time intervals. In the first method, the current vector at the end of the interval is predicted for two possible cases when either the active voltage vector pointing toward current error or the zero voltage vector is applied. The one producing the smaller current error at the end of the sampling interval is chosen, thus obtaining drastic reduction of the switching frequency. In the second method, the best fitting active voltage vector succeeds the zero vector during the same time interval. A simple algorithm is used to calculate the duty cycle thus gaining the smallest possible current error. The method is compared with the CRPWM. Both methods were simulated and tested on a laboratory model with passive load. In the last part of the paper, the behavior of the second method is tested for erroneously estimated load parameters. The two methods show very small degradation of performance even when a rather high parameter error is introduced.

System and method for measuring battery current

Abstract: Systems, devices and methods are provided for measuring battery current. According to one aspect, a medical device is provided that comprises a battery, a pulse generator, and a current measuring device. The pulse generator draws a pulse generator current from the power source, and the current measuring device determines the pulse generator current or tracks charge depletion from the battery. The current measuring device comprises an oscillator and a counter. The oscillator produces an oscillating output with a frequency of oscillation dependent on the pulse generator current, and the counter provides an oscillation count for the oscillating output. The current measuring device is capable of being calibrated while continuously determining the pulse generator current. In one embodiment, the current measuring device includes at least two current sources, each including an operational amplifier that has an autozeroing feature.

Motor drive control with a single current sensor using space vector technique

Abstract: A drive system for a three phase brushless AC motor is arranged to optimize the transistor switching pattern to improve power output whilst allowing current measurement in all of the phases using a single sensor. This is achieved by defining voltage demand vectors x where more than two states are required to meet a minimum state time requirement determined by the single sensor method, and calculating three or more state vectors which produce the demanded vector x whilst still allowing single current sensing. Various methods of optimising the PWM pattern so as to give maximum output whilst using single current sensing are also disclosed.

Current measuring method and current measuring device

Abstract: A current measuring method capable of reducing the size of a current sensor while ensuring electric insulation easily and suitable for enhancing reliability by preventing heat generation. A current measuring device comprises a printed board ( 3 ) having a conductor for measurement ( 4 ), and a noncontact current sensor ( 100 ) being mounted on the printed board ( 3 ), wherein the current sensor ( 100 ) is mounted on the surface ( 92 ) of the printed board ( 3 ) opposite to the side provided with the conductor for measurement ( 4 ). Since the current sensor ( 100 ) is mounted on the rear surface ( 92 ), electric insulation between the secondary conductor of the current sensor ( 100 ) and the conductor for measurement ( 4 ) can be ensured relatively easy.

Constant current output control method and constant current output control device for switching power supply circuit

Abstract: A constant current output control method and device for a switching power supply circuit for constant current output control of an output current I 2o of a rectifying smoothing. An OFF adjustment time T 3 is: T 3 =T 2 ×( Np÷Ns×Ip ref ÷2 ÷I 2oset −1)− T 1 (1) in which, I 2oset represents a set output current of the rectifying smoothing circuit, Np represents a number of turns of a primary winding, Ns represents a number of turns of a secondary winding, T 1 being a fixed time representing an ON time, Ip ref representing a reference peak current flowing in the primary winding, and T 2 representing an output time during which output is generated from the rectifying smoothing circuit. Output current I 2o during an oscillation period T becomes set output current I 2oset , and constant current output control can be executed by repeating this method.

Sensor arrangement and method for operating a sensor arrangement

Abstract: The invention relates to a sensor arrangement (800) and a method for operating a sensor arrangement. The sensor arrangement contains a plurality of sensor devices (600) embodied on and/or in a substrate. Each of the sensor devices comprises an electric signal converter (601) and a sensor element (602) coupled to the signal converter in order to characteristically influence the electrical conductivity of the signal converter as a result of a sensor event on the sensor element. Each sensor device comprises a device (603) for keeping an electric voltage, which is applied to the signal converter, constant and a device (603) for detecting the value of the electric current flowing through the signal converter in the form of a sensor signal.

Power conversion apparatus and power conversion system having the power conversion apparatus

Abstract: A power conversion apparatus of this invention includes a power switching device, a voltage sensor, a current sensor, and a device controller connected to the switching device, the voltage sensor, and the current sensor. The voltage sensor detects an output voltage of the switching device to output a first signal depending on the output voltage, and the current sensor detects an output current of the switching device to output a second signal depending on the output current. The device controller includes a driver connected to the switching device and a correcter connected to the driver, the voltage sensor and the current sensor. The driver outputs a third drive signal to the switching device. The correcter monitors a switching loss and a surge voltage by using the first and second signals, and corrects the third signal depending on values of the switching loss and the surge voltage.

Computer system having controlled cooling

Abstract: A computer system and its method of cooling are provided. A vapor chamber serves as a heat spreader for heat from the microelectronic die. A thermoelectric module serves to cool the vapor chamber and maintain proper functioning of the vapor chamber, thus keeping the microelectronic die cooled. A controller receives input from five temperature sensors, and utilizes the input to control current to the thermoelectric module and voltage/current to a motor that drives a fan and provides additional cooling. A current sensor allows the controller to monitor and limit power provided to the thermoelectric module.

Coreless current sensor

Abstract: A time varying current sensor is constructed using surface coils uniformly spaced around a central cavity adapted to receive the conductor through which the current to be measured flows. Accurate and uniform coil geometry is achieved using printed circuit board technology, thereby eliminating the high cost of precision toroidal coil winding. An optional hinge in the housing can allow the sensor to be easily installed on existing conductors without the need to disconnect and reconnect.

Electromagnetic MWD telemetry system incorporating a current sensing transformer

Abstract: An electromagnetic telemetry system for transmitting data from a downhole assembly, which is operationally attached to a drill string, to a telemetry receiver system. The data are typically responses of one or more sensors disposed within the downhole assembly. A downhole transmitter induces a signal current within the drill string. The signal current is modulated to represent the transmitted data. Induced signal current is measured directly with the telemetry receiver system. The telemetry receiver system includes a transformer that surrounds the path of the current, and an electromagnetic current receiver. The transformer preferably comprises a toroid that responds directly to the induced signal current. Output from the transformer is input to an electromagnetic current receiver located remote from the downhole assembly and typically at the surface of the earth. Alternately, voltage resulting from the induced signal current can be measured with a rig voltage receiver and combined with the direct current measurements to enhance signal to noise ratio.

Light emitting element display apparatus and driving method thereof

Abstract: A display apparatus includes signal lines to each of which a current is supplied to obtain an arbitrary current value, optical elements each optical behaving in accordance with the current value of the current flowing via the signal line, and a stationary voltage supply circuit for supplying a stationary voltage for setting the current value of the current flowing through the signal line to be stationary through the signal line.

Temperature sensor and method for detecting trip temperature of a temperature sensor

Abstract: A comparator circuit of a temperature sensor includes an output node and a variable current node. The output node is a first voltage at a given temperature when a current at the variable current node is less than a threshold current, and a different second voltage at the given temperature when the current at the variable current node is more than the threshold current. A variable resistance circuit includes at least n resistors of different resistive values connected in series between the variable current node of the comparator and a supply voltage, where n is an integer of 4 or more. A switching circuit is provided to selectively bypasses individual ones of the n resistors during a test sequence to determine a trip temperature of the sensor.

A current reconstruction algorithm for three-phase inverters using integrated current sensors in the low-side switches

Abstract: Power semiconductor switches that include integrated pilot current sensors create opportunities to eliminate external current sensors in three-phase inverter applications. Each of the three conventional low-side power switches in a three-phase inverter can be replaced by one of these special devices that is designed to provide a sensing level current that accurately mirrors its total forward current. Recognizing that the output current in each phase flows through the low-side switch for only a portion of the fundamental cycle, a technique has been developed to reconstruct the full phase current waveforms for R-L loads using only the incomplete phase current measurements. The performance characteristics of the proposed current reconstruction technique are experimentally verified, including demonstration of a closed-loop three-phase current regulator using the reconstructed current feedback from the integrated pilot current sensors.

Method and circuit for driving a gas discharge lamp

Abstract: Circuit and method for driving a gas discharge lamp having a bridge converter. The bridge converter includes a plurality of switches. A controller turns on and off the plurality of switches. The circuit further includes a zero current sensor circuit. The controller senses at least one voltage differential to control a length of time that at least one of the at least four switches is on. The controller controls when at least one of the plurality of switches is turned on in accordance with an output of the zero cross sensor.

Current control loop for actuator and method

Abstract: Systems and methods for providing a current control loop for an actuator. A typical system includes a current command controller setting a command current, the current command controller being coupled to a drive circuit used to drive the actuator and a sampling module sampling a motor current of the actuator. The system also includes a summation module calculating a current error based on the motor current, the current error being calculated by subtracting the motor current from the command current. The current error is used to compensate for an error in the motor current of the actuator. The sampling module can include a switch and a capacitor coupled in parallel with the resistor when the switch is on, a charge on the capacitor being proportional to the voltage drop across the resistor. Methods for setting a maximum control current and for providing the current control loop are also illustrated.

A method to damp oscillations on the input LC filter of current-type AC-DC PWM converters by using a virtual resistor

Abstract: A control method to damp oscillations on the input LC filter of current-type AC-DC PWM converters is proposed in this paper. The oscillations on the input LC filter of current-type AC-DC PWM converters are damped by using a virtual resistor that can be connected either in series to or parallel with the filter inductor or capacitor. Because no real resistor is used, the efficiency of the converters is not sacrificed. The required additional sensor and implementation of the virtual resistor in the control algorithm is strongly influenced on how the virtual resistor is connected to the LC filter. We need an additional current sensor if the virtual resistor is connected in series to the filter inductor or capacitor and an additional voltage sensor if connected in parallel. Simulated results are included to verify the proposed method.

EL display panel driving method

Abstract: In order to charge and discharge parasitic capacitance of a source signal line sufficiently and program a predetermined current value into a pixel transistor, it is necessary to output a relatively large current from the source driver circuit. However, if such a large current is passed through the source signal line, the value of this current is programmed into the pixel, causing a larger than desired current to flow through an EL element. For example, if a 10 times larger current is used for programming, a 10 times larger current flows through the EL element, and thus the EL element illuminates 10 times more brightly. To obtain predetermined emission brightness, the time during which the current flows through the EL element can be reduced to 1/10 of one frame (1 F). This way, the parasitic capacitance of the source signal line can be charged and discharged sufficiently and the predetermined emission brightness can be obtained.

Control for battery pack

Abstract: A battery pack of a series combination of cell units is connected with a motor drive control circuit to drive a traction motor for a vehicle. A current sensor senses a discharge/charge current of the battery pack, and a voltage detecting circuit senses a voltage between two separate points in the series combination of the battery pack. A memory section stores a reference voltage drop quantity representing a decrease in voltage during a predetermined time interval between the two separate points. An offset detecting section compares an actual voltage drop quantity sensed by the voltage detecting circuit, with the reference voltage drop quantity, thereby detects a non-discharge/charge-current state of the current sensor, and reserves an output of the current sensor, as an offset quantity upon the detection. A correcting section corrects a sensed value of the discharge/charge current with the reserved offset quantity.

Stabilized power supply unit having a current limiting function

Abstract: In a stabilized power supply unit having a current limiting function, the unit is designed to have a steep over-current dropping characteristic. This minimizes the over-current region, prevents oscillation during a startup, and limits inrush current during a start up within a predetermined range. The output voltage of the power supply unit provides a constant output voltage by controlling an output transistor by means of a differential amplifier amplifying the difference between a reference voltage and an output feedback voltage. The power supply unit has a first high-gain, slow-response type current limiting circuit that outputs a first current limiting signal when the output current of the power supply unit exceeds a predetermined level, and a second low-gain, quick-response type current limiting circuit that outputs a second current limiting signal when the outputs exceeds the predetermined level.

System and method for clamp current regulation in field-weakening operation of permanent magnet (PM) machines

Abstract: A device to regulate current produced by a permanent magnet machine responsive to a plurality of phase current signals. The motor produces torque for application on a shaft. A processing and drive circuit responsive to a direct current command signal and a quadrature current command signal produces phase current signals for input to the motor. A command circuit responsive to the phase current signals, an angular position of said shaft, and a voltage input command signal to produce a direct current error signal and a quadrature current error signal. A control circuit responsive to the direct and quadrature current error signals produces the direct voltage signal command and the quadrature voltage signal command. The control circuit has a direct and quadrature proportional gain, integrator and clamp circuits. An algorithm produces limited or clamped voltage modulation index signals to obtain maximum efficiency and maximum torque per ampere in the speed range. The algorithm ensures that the current regulator does not run out of voltage by limiting the voltage vector to the achievable voltage vector range that provides maximum torque per ampere and maximum efficiency.

Voltage regulator with dynamically boosted bias current

Abstract: A voltage regulator with dynamically boosted bias current includes a pass device (14a) for providing current to a load (12a); an error circuit responsive to a difference between a predetermined reference voltage and a function of the voltage on the load (12a) to produce an error signal, a driver circuit (16a) responsive to the error signal for controlling the pass device (14a) to adjust the current to the load (12a) to reduce the error signal, the driver circuit (16a) including an amplifier (30a) responsive to the error signal for controlling the pass device (14a), a bias current source (156) for biasing the amplifier (30), a sensing circuit (160) for sensing a portion of the error signal, a reference current source (172) for providing a reference current, a second error circuit (170) responsive to a difference between the portion of the error signal and the reference current to produce a second error current; and a boost circuit (174) responsive to the second error signal to increase the bias current provided to the amplifier (30a) when the load demands more current.

Methods and apparatus for fault-tolerant control of electric machines

Abstract: A method for controlling an electric machine having current sensors for less than every phase of the electric machine includes operating a processor to perform a test to preliminarily determine whether a fault exists in one or more of the current sensors and a test to finally determine that the fault exists in the one or more current sensors. The method further includes operating the processor to utilize a state observer of the electric machine to estimate states of the electric machine, wherein the state observer is provided state input measurements from each non-faulty current sensor, if any. Measurements from the current sensor or sensors determined to be faulty are disregarded. The processor controls the electric machine utilizing results from the state observer.