Showing papers on "Constant current published in 1993"

Rechargeable battery charging method

Abstract: A hysteresis battery charging method repeats peak and trough voltage and current waveforms taking the battery to a temporary over-voltage state during peak charging. This method achieves rapid recharge while avoiding battery performance degradation. Constant current charging or quasi-constant current charging is performed during peak charging. During troughs, charging is either suspended or reduced from that during peak charging. After battery capacity has reached a set value by hysteresis charging, an optimum voltage is maintained by constant voltage charging.

Quasi-resonant diode drive current source

Abstract: A quasi-resonant diode drive current source provides high power pulsed current that drives light emitting diodes, and the like. The pulsed output current of the quasi-resonant diode drive current source is sensed, and is regulated by a control loop to a level required by the light emitting diodes. In a specific embodiment of the invention, a zero-current-switched full wave quasi-resonant buck converter is described that provides a high amplitude pulsed output current required to drive light emitting pump diodes used in a solid state diode pumped laser. The use of a quasi-resonant converter as a pulsed current source provides a much higher conversion efficiency than conventional laser current sources. This higher efficiency results in less input power drawn from a power source and cooler operation, resulting in a higher reliability current source.

Power supply for electronic device, and electronic device system

Abstract: To make it possible to supply to a battery a charging current having a sufficient capacity which enables a short-time charge while supplying a drive current for usual operation to a battery operable electronic device, without making construction large-sized and complicated. The present invention is intended to be able to delicately vary a charging current of a battery according to the variation of power consumption of load on an electronic device, by providing constant power feedback control means for performing feedback control of the output power so as to cause a constant power or a nearly constant power, based on a current feedback value and a voltage feedback value.

Circuit for detecting a paper at a desired position along a paper feed path with a one shot multivibrator actuating circuit

Abstract: A print paper detecting circuit for installation on a printer, to detect whether a print paper is supplied at a predetermined position along a paper path by using an optical sensor composed of a light emitting diode and phototransistor. The circuit detects the existence of the print paper according to the detection of light which is emitted from the light emitting diode, which is reflected from the print paper, and which arrives at the phototransistor. According to one embodiment, circuit has a current amplifier and a gain reducing circuit. The current amplifier feeds a pulse current which is greater than the normal constant current to the light emitting diode while the gain reducing circuit reduces the output of the output voltage. From the phototransistor during the time that the pulse current is supplied with this circuit arrangement any external light entering the printer does not affect the detection of the presence of the printer paper since the quantity of the light from the light emitting diode is greater than the quantity of the external light.

Low power VCC and temperature independent oscillator

Abstract: 57 A constant current source (100) is used to provide a constant current (1 2 ) to set a delay which defines the period of the output of the oscillator. The delay is preferably set by charging a capacitor (200) with the constant current (1 2 ). Because the current (1 2 ) is independent of variations in the power supply voltage (V cc ) and temperature, the capacitor (200) will charge for a given period. Therefore, the frequency or period of oscillation will also be fixed and independent of variation in the power supply voltage (V cc ) or temperature. A current limiting circuit (300) and latch (400) are provided to generate an output (PULSE A) which will be transmitted through one or a series of inverters. In an alternate embodiment, a differential amplifier (600) is provided between the delay circuit (200) and the current limiting circuit (300). This differential amplifier (600) is typically needed in a case where the power supply voltage (V cc ) is not well-controlled to provide an output signal which has an appropriate voltage. A method of generating an oscillating output (PULSE A) for refreshing a DRAM and a method for refreshing a DRAM are also disclosed.

System for improving measurement accuracy of transducer by measuring transducer temperature and resistance change using thermoelectric voltages

Abstract: A constant current loop measuring system measures a property including the temperature of a sensor responsive to an external condition being measured. The measuring system includes thermocouple conductors connected to the sensor, sensing first and second induced voltages responsive to the external condition. In addition, the measuring system includes a current generator and reversor generating a constant current, and supplying the constant current to the thermocouple conductors in forward and reverse directions generating first and second measured voltages, and a determining unit receiving the first and second measured voltages from the current generator and reversor, and determining the temperature of the sensor responsive to the first and second measured voltages.

Alkaline battery charging method and bettery charger

Abstract: A battery charger and method are disclosed for charging alkaline, Ni-Cad and zinc-based batteries, particularly sizes N, AAA, AA, C and D. For batteries rated at about 1.25 volts to about 1.5 volts, the battery charger and method provide a constant charging current of between about 0.28 ma to about 1.5 ma per gram weight of the battery. A constant current circuit under control of a controller provides the constant current to the battery under charge. A reference voltage generator generates reference voltages as the battery is being charged while the controller frequently monitors the battery voltage and compares it to the reference voltage. A substantially constant current is supplied to the battery while a reference voltage greater than the battery voltage is provided. Thereafter, as the battery voltage increases, the reference voltage is incremented up to a predetermined maximum reference voltage. The controller causes the constant current circuit to terminate the supply of current to the battery when the reference voltage reaches the predetermined maximum, or when the battery voltage does not increase during charging to be greater than a first or a subsequent reference voltage during a predetermined charging time period. The controller may also cause the constant current circuit to supply from time to time a substantially constant test current to the battery which exceeds the charging current by from about 2.5 % to about 25 % for up to a predetermined testing time period, and terminate the supply of current to the battery if the test current increases by greater than a predetermined amount within the predetermined testing time period. The battery charger may at the same time charge batteries of different sizes, and includes a separate constant current circuit for each battery in the battery charger. Each battery is constinuously supplied with charging or testing current as determined by the controller, and the controller controls charging of each battery independently of the charge condition of any other battery. A separate controller may control each constant current circuit, or a microprocessor may control all of the constant current circuits.

Current controller for controlling a current flowing in a load using a PWM inverter and method used thereby

Abstract: A current controller has provided therein assumed response generating means and load model means so as to realize repetitive type control with no influence of control delay against a periodically repetitive current response. This current controller is applied to a 120-degree current flow type motor using a pulse width modulation inverter, so that the DC current control including the process of response to the rise of the current can be realized only by a microcomputer.

Differential to single-ended converter

Abstract: A differential to single-ended converter includes a voltage-to-current converter that converts differential voltage input signals to differential current signals which differ by a difference current. A current mirror mirrors the first differential current signal. A substantially constant DC voltage level is established. A resistor conducts any difference in current between the mirrored current and the second differential current signal and translates this difference current to a single-ended voltage output signal. An input buffer provides the differential voltage input signals to the voltage-to-current converters.

Power semiconductor device

Abstract: A power semiconductor device is constructed by integrating a DMOS transistor and a lateral MOS transistor on the same semiconductor chip. The lateral MOS transistor is formed within a well with a conductivity type which is the same as the conductivity type of the source region of the DMOS transistor. The gate voltage is monitored at the time of connecting the gate and the drain of the lateral MOS transistor and of driving it at a constant current. When the gate voltage drops below a predetermined value, the driving of the DMOS transistor is stopped. The breakdown of the power semiconductor device due to heating can thus be prevented.

Variable thermal sensor

Abstract: A thermal sensor for use in integrated circuits includes a plurality of MOSFET diodes. The thermal sensor senses temperature within the integrated circuit and provides a control signal. The control signal may be utilized to control thermal management devices such as fans, clock dividers, or other thermal management devices. The thermal sensor is preferably integrated within the microprocessor adjacent clock driver circuitry. The thermal sensor generally includes current mirrors coupled to diodes. The diodes control the output of the current mirrors so that larger current is drawn from the current mirrors when the temperature is higher in the integrated circuit. The current mirrors supply current to a constant signal source and an impedance circuit. The control circuit compares the voltages from the impedance circuit and the constant signal source. The control circuit provides the control signal when the signal from the impedance circuit is above a predetermined threshold.

On-line simulation of voltage regulation in autotransformer-fed AC electric railroad traction networks

Abstract: Simulation algorithms to model the voltage distribution characteristics in AC autotransformer-fed railroads with single- and double-end supply are described. The theory is based on the solution of algebraic equations for a single train, moving along a track section represented as a coupled transmission line. The simulation was implemented on a PC with continuous displays of the catenary and rail voltages, and an historical record of the train voltage for movement at constant speed along the section. The simulator enables rapid parametric analyses to be made in order to optimize the power feeding arrangement, and sample displays of catenary, rail, and train voltages are given for single train operation under constant current and constant power. >

Power regulator of discharge lamp and variable color illumination apparatus using the regulator

Abstract: A current supplied to a discharge lamp (100) is an A.C. current having a predetermined frequency from an inverter circuit (70), and its power control is carried out by changing the current setting (setting signal) of a chopper circuit (40) constituting a constant current circuit. In other words, when a value is set by an output luminance regulator (120), this set current value is inputted to a chopper control circuit (130). The chopper control circuit (130) checks the current detected by a current detector (110) and outputs a current control signal to a gate terminal (41) of the chopper circuit (40) so that the output current may coincide with the set current value. Accordingly, the power supplied from the inverter circuit (70) to the discharge lamp (100) is controlled by the chopper circuit (40).

Control equipment for high voltage direct current transmission system with equipment of self-commutated converter

Abstract: A high voltage dc transmission system uses equipment of self-commutated converters each of which comprises switching devices with a self-commutating (gate-turn-off) function A first control equipment associated with the rectifier comprises a constant reactive power (var) control circuit for holding constant the reactive power on the input side of the rectifier, and a constant dc voltage control circuit for holding constant the dc system voltage on the output side thereof A second control equipment associated with the inverter comprises a constant reactive power control circuit for holding constant the reactive power on the output side of the inverter, and a constant active power control circuit for holding constant the active power on the output side thereof The first control equipment and the second control equipment each have a current control circuit for making independent control of each component of a two-phase current resulted from transformation of a three-phase ac current

Constant current generating circuit for semiconductor devices

Abstract: The constant current generating circuit includes a high resistance element for generating a very small current. This very small current is supplied to a first MOS transistor having a sufficiently large gate width to gate length ratio. The gate-source voltage of the first MOS transistor becomes its threshold voltage VTH, and the voltage applied across a resistance connected between the gate of the first MOS transistor and the ground line is set to a constant value VTH. Thus, a constant current is normally passed through the resistance. Since the very small current is supplied from the high resistance element which is normally turned on, regardless of the change of the power supply voltage, a constant current can be generated stably.

PTAT current source

Abstract: A current source for producing a current that is proportional to absolute temperature (i.e., "PTAT") is disclosed. The current source is based upon a circuit having a pair of current mirrors, one based upon MOS transistors and the other based upon bipolar transistors, where each of two legs in the current source include the series connection of one of the MOS transistors with one of the bipolar transistors. Further included in the disclosed circuit is a series connection of three MOS startup transistors, useful in starting up the current source in a non-critical manner. A startup current source, sourcing a non-critical startup current, turns on one of the MOS startup transistors that is connected in current mirror fashion with the MOS transistor current mirror, turning on both current mirrors. As the output current increases, the current through the MOS startup transistors also increases, until equilibrium is achieved. Early effects in the bipolar transistor current mirror are eliminated by maintaining the gate-to-source voltage of the MOS transistors equal, without requiring cascode transistors, and thus maintaining low voltage operating capability.

Semiconductor integrated circuit having power reduction mechanism and electronic device using same

Abstract: PURPOSE:To provide the semiconductor integrated circuit with a high speed circuit operation and low power consumption and the electronic device using the integrated circuit. CONSTITUTION:An MOS TR circuit L and a means controlling current supply (switches SC, SS and resistors RC, RS) of a large current and a small current is inserted between a power supply VCC and a power supply VSS. A large or a small current is a switched depending on a use and supplied to the MOS TR circuit L. The electronic device is configured by using the MOS TR circuit L depending on the use. Thus, a low power consumption characteristic is obtained with the small current supply to be selected in the standby state and a high speed performance is obtained by selecting a large current in the operation.

Clamping circuit for clamping a reference voltage at a predetermined level

Abstract: A clamping circuit includes a constant current circuit including a constant current source and a current mirror circuit a trimmable resistance receiving a constant current from the constant current circuit, and a clamping MOS transistor receiving a voltage generated by the trimmable resistance at its gate to regulate a current flowing through a clamping node. It is possible to make rapid a current-voltage characteristic of the clamping circuit, and to set an arbitrary clamping potential.

Isolated current sensor for DC to high frequency applications

Abstract: Current in a line is measured by passing it through a coil, having at least one turn, linking a small high permeability core; passing a measuring current through a bucking winding around the same core; and controlling the measuring current to buck the magnetomotive force of the line current so that the core flux stays below the saturation level. The measuring current may flow through a precision resistor so that a voltage across the resistor is an accurate measure of the line current. The measuring current is obtained from a high frequency switching circuit which senses the change of flux in the core. In normal operation the circuit switches when the core flux has risen to a predetermined value, such as 60% or 80% of the saturation value. If drift or extreme transients cause the flux to reach the saturation level, a sensing and correction circuit re-establishes operation between the desired points.

Integrated circuit driver having current limiter for brushless motor

Abstract: An integrated circuit driver for a brushless motor having an encoder which includes a plurality of Hall-effect sensors operative for providing commutation information to a motor controller includes a commutation decoding section for decoding the commutation information from the Hall-effect sensors and an analog current limiter. The current limiter includes a circuit for dynamically switching the current limit values for current in the motor between a high current limit value and a low current limit value based on the average or RMS value of the motor winding current. The current limit values must be provided externally. A Hall-effect sensor quadrature encoder is provided on the integrated circuit and a selection switch allows for the selection of a quadrature output from an external optical encoder or the internal Hall-effect sensor encoder.

Rotating telecommunications power supply

Abstract: A low noise, essentially ripple free power supply for supplying power to a telecommunications system includes a gasoline, propane, natural gas or diesel fueled engine driving a rotating field power generator to produce an alternating current output which is then rectified and applied to a special filter circuit to provide an output current having less than 100 mVolts ripple and less than 22 dBrnc noise, which is acceptable to the telecommunications industry. A current sensor connected to the output of said filter circuit monitors the output current to the telecommunications system, and a regulator circuit responds to the voltage and current output of the power supply to control current to the rotating field coils to provide a regulated, substantially constant, output voltage level up to a predetermined maximum current output. A high voltage shutdown circuit shuts down the engine and opens a circuit breaker whenever the voltage output to the telecommunications system exceeds a predetermined level.

Dead-time effect compensation for pulse-width modulated inverters and converters

Abstract: Polarity change of a feed-forward compensation signal for compensating for a dead-time voltage disturbance is synchronized with zero crossings of a load current reference. The load current reference is advanced in time by adding a fixed phase angle, scaled by the synchronous frequency, to the synchronous coordinates angle. The load current reference is time-advanced only for timing the polarity change of the feed-forward compensation signal and not for application to the current regulators; the current regulators still use the load current reference (unadvanced). For a converter, the load current would be an AC mains input current. For an inverter, the load current could, for example, be an induction motor stator current. The shape of the feed-forward compensation signal is approximately trapezoidal and is obtained from the limited, amplified, advanced load current reference. The shape of the feed-forward compensation signal is a function of at least one of: the load current frequency, the load current amplitude and an amplification scaler.

A small-signal model for SEPIC, Cuk and flyback converters as power factor preregulators in discontinuous conduction mode

Abstract: The authors describe small-signal models for SEPIC, Cuk, and flyback converters as power factor preregulators in discontinuous conduction mode (voltage follower approach) and constant frequency, using CIECA (current injected equivalent circuit approach). Implementations with and without input voltage feedforward, using resistive load, constant power and constant current loads, are analyzed, and their respective transfer functions are obtained. The applicability of an integrated circuit (usually used in continuous conduction mode) in the control loop is also presented. Simulation results are presented, validating the models to be used in control loop design. >

The constant current loop - A new paradigm for resistance signal conditioning

Abstract: A practical, single, constant-current loop circuit for the signal conditioning of variable-resistance transducers was synthesized, analyzed, and demonstrated. The strain gage and the resistance temperature device are examples of variable-resistance sensors. Lead wires connect variable-resistance sensors to remotely located signal-conditioning hardware. The presence of lead wires in the conventional Wheatstone bridge signal-conditioning circuit introduces undesired effects that reduce the quality of the data from the remote sensors. A practical approach is presented for suppressing essentially all lead wire resistance effects while indicating only the change in resistance value. Theoretical predictions supported by laboratory testing confirm the following features of the approach: (1) the dc response; (2) the electrical output is unaffected by extremely large variations in the resistance of any or all lead wires; (3) the electrical output remains zero for no change in gage resistance; (4) the electrical output is inherently linear with respect to gage resistance change; (5) the sensitivity is double that of a Wheatstone bridge circuit; and (6) the same excitation and sense wires can serve multiple independent gages. An adaptation of the current loop circuit is presented that simultaneously provides an output signal voltage directly proportional to transducer resistance change and provides temperature information that is unaffected by transducer and lead wire resistance variations. These innovations are the subject of NASA patent applications.

Control equipment for high voltage direct current transmission system

Abstract: The high voltage dc transmission system uses equipment of self-commutated converters (3, 5) each of which comprises switching devices with a self-commutating (gate-turn-off) function. A first control equipment (31) associated with the rectifier (3) comprises a constant reactive power (var) control circuit (319) for holding constant the reactive power on the input side of the rectifier (3), and a constant dc voltage control circuit (318) for holding constant the dc system voltage on the output side thereof. A second control equipment (51) associated with the inverter (5) comprises a constant reactive power control circuit (508) for holding constant the reactive power on the output side of the inverter (5), and a constant power control circuit (507) for holding constant the active power on the output side thereof. The first control equipment (31) and the second control equipment (51) each have a current control circuit for making independent control of each component of a two-phase current resulted from transformation of a three-phase ac current.

A new probe for measuring electrolytic conductance

Abstract: A conductance cell of which the electrodes are provided with a 110 nm thick Ta2O5 insulating film is proposed and realized. The stable and very low impedance of the total oxide/solution interface largely reduces interference from redox processes. Measurement results, given as an output voltage between 10 and 600 mV as a function of the specific resistance between 0.1 and 8 k?, are shown to be in agreement with theoretically calculated results, both at the constant current and constant voltage mode of operation.

Corrosion preventing circuit for switch

Abstract: Disclosed is a corrosion preventing circuit for a switch which, even if a large current switch is used for a small current system such as an electronic unit, can improve long-term durability of the switch in a manner similar to the present level without increasing the burden on the system side, thereby ensuring the reliability of devices belonging to the system. A series circuit consisting of a switching means and a current limiting resistor is connected in parallel to a resistor that is connected in series between a dc power supply and a large current switch. A control circuit turns on the switching means by generating a pulse of a predetermined time width after a predetermined time in accordance with the turning on of the large current switch. The current flowing while the switching means is being turned on is applied to the large current switch, so that an oxide film formed at the contact of the switch is destroyed.

Device for anesthetizing and treating eardrum

Abstract: PURPOSE: To provide a device of very high safety capable of preventing wrong operation due to the large number of many user, by having circuits operating as treating device and control circuit for backing to an original condution of anesthetizing device after predetermined time. CONSTITUTION: When operated as a treating device, a signal of inversion switch 42 is emitted to a control circuit 43. By the output thereof a timer 21 and constant current circuit 20 are switched to time for treatment Y and current value for treatment N. At the same time, the polarity is inverted by output from inversion signal output terminal 51 and a closed circuit for treatment is formed. With start switch 22 ON, the signal of treatment time Y is emitted to the constant current circuit 20 from the timer 21, the constant current is carried by the constant current circuit 20 and after time provided for the treatment is over, the treatment is finished. After predetermined time, a reset signal from the timer 21 is outputted, the timer 21 and the constant current circuit 20 are backed to anesthetizing mode, the polarity is backed to the original condition and the device is backed to the original condition of actuating the operation as anesthetizing device and is waiting. COPYRIGHT: (C)1995,JPO

Battery charger apparatus and method with multiple range current control

Abstract: An improved battery charger apparatus and method with multiple range current control includes a programmable current source (101) for providing a charge current (105) to charge a battery (107). An amplitude of the charge current (105) is dependent on a charge demand signal (117) supplied to the programmable current source (101). A scaler (109) provides a scaled charge current signal (111), dependent on the charge current (105) and a current range signal (113). A charge current control unit (115) regulates the charge current (105) by providing the charge demand signal (117) to the programmable current source (101) dependent on the scaled charge current signal (111). More than one amplitude of the charge current (105) is provided to the battery (107), dependent on more than one current range signal (113) provided by the charge current control unit (115) to the scaler (109). Moreover, a constant amplitude of the scaled charge current signal (111) is maintained responsive to the more than one current range signal (113).