Showing papers on "Constant current published in 1980"

Battery state of charge evaluator system

Abstract: A microprocessor based electric vehicle traction battery monitoring system evaluates the state of charge, interfaces with a traction motor control system, and controls recharging. The state of charge is evaluated during the first part of discharge by integrating the current after compensating it for rate of discharge and during the last part of discharge by dividing the battery into sub-packs and evaluating the state of charge from the lowest sub-pack voltage compensated for polarization voltage. The charge storage capacity is also calculated from the lowest sub-pack voltage. The maximum traction motor current is progressively limited during the last part of discharge. During charging, the charge withdrawn is replaced while progressively reducing the charging current and the battery is then charged at a constant current until the rate of rise of the lowest sub-pack voltage falls below a fixed level.

Pulse arc welding device

Abstract: PURPOSE: To reduce arc voltage, prevent arc breaking and stabilize the arc by increasing background current when an arc voltage detected value rises above a set value. CONSTITUTION: A pulse current waveform is supplied to the arc 6 by a pulse current source 21 and a background current source 22. At this time, the arc voltage is detected with an arc voltage detector 23 and is compared with the reference voltage of an arc voltage reference setter 24 in a comparator 25. When the arc voltage is larger than the reference voltage, a current increase command is given from the comparator 25 to the source 22 which in turn flows the current added with the current value having beforehand been corrected with a background current corrector 26 to the arc 6. Hence, when it comes to the point of the time I when the arc is liable to break in the background part, the arc voltage rises and at the same time the background current value 2 begins to lower. At the point of the time II when the arc voltage exceeds the reference voltage, the background current 2 is increased, thereby stabilizing the arc. Then, the arc voltage decreases and at the same instant the command of the comparator 25 stops. At the point of the time III, the background current resumes the original value. COPYRIGHT: (C)1982,JPO&Japio

Gas metal arc welding system

Abstract: Power delivered to the welding arc from a constant current rapid response power supply is controllable to maximize arc stability particularly in out-of-position welding operations. A first control modulates the output current from the power supply between a high value close to the maximum output value and a minimum value just sufficient to maintain the welding arc. The modulation is effected at a given frequency appropriately adjusted in accordance with the electrode material and diameter to maintain optimum spray metal transfer in the welding arc. A further control is effected by pulse width modulating the output from the power supply in accord with a set-in current programmed signal which is compared with a current feedback signal or, alternatively, a set in voltage programmed signal which is compared with a voltage feedback signal. This latter control provides for operation of the power supply in a constant current control mode or alternatively, a constant voltage control mode. Still further control of the power in the welding arc is effected by pulsing the current between base and peak levels at a relatively low frequency which enables control of the weld puddle in out-of-weld positions.

Injector drive circuit

Abstract: An injector drive circuit for driving an injector having a valve opened and closed according to a pulse signal with the pulse duration thereof corresponding to the quantity of fuel supplied to the engine. The injector drive circuit comprises a current supply power transistor connected to an injector coil. According to an electric pulse signal from a fuel injection control circuit, a first current control section causes base current to flow into the power transistor for causing a peak current through the injector coil. When a predetermined peak current is detected, the base current supplied by the first current control section is cut off. From this instant till the disappearence of the electric pulse signal, a second current control section, which supplies base current to the power transistor only when the current supplied from the power transistor to the injector coil becomes lower than a working current level, supplies in effect the working current through the power transistor to the injector.

Constant current circuit

Abstract: Disclosed is a constant current circuit comprising first and second P channel MOS transistors (56, 62) coupled with each other so as to form a current mirror circuit, first and second N channel MOS transistors (60, 64) having current paths respectively connected in series with the current paths of the first and second P channel MOS transistors (56, 62), and a third N channel MOS transistor (66) which is connected at the gate to the drain of the first N channel MOS transistor (60) and the gate of the second N channel MOS transistor (64), and feeds a current controlled by the drain voltage of the first N channel MOS transistor (60) to a load (68). The constant current circuit further includes a resistor (58) which is connected at one end to the drain of the first P channel MOS transistor (56) and the gate of the first N channel MOS transistor (60), and at the other end to the drain of the first N channel MOS transistor (60).

Two terminal Hall-sensor

Abstract: An integrated circuit includes a Hall-element, a voltage regulator, and a threshold detector. DC power is supplied through a pair of terminals that may be connected to a remote DC voltage source. A switchable constant current sink circuit connected across these terminals is turned on and off in response to the two output states of the threshold detector that in turn is responsive to the Hall-element output voltage. Thus the DC current flowing in the two DC supply lines is a predictable large value or small value corresponding to a low and a high magnitude magnetic field at the sensor, even when the supply DC voltage changes over a wide range.

Apparatus for driving hot-wire type flow sensor

Abstract: An apparatus for driving a hot-wire air-flow sensor of constant temperature difference type includes a hot wire and a temperature sensitive compensating element such as a resistor for compensating temperature of air. The hot wire and the resistor are formed of identical elements. A pulse train signal having a pulse width varying in correspondence to difference between voltage drops produced, respectively, across the hot wire and the compensating resistor supplied with a constant current is produced for interrupting the current supplied to the hot wire.

Lamp circuit with disconnected lamp detecting device

Abstract: A lamp circuit is provided having a constant current type AC power source and a plurality of isolation transformers connected in series with the AC power source. The secondary circuit of each isolation transformer is connected to an electric lamp. The voltage-time area, which is measured from the rise of the voltage output signal of the power source to the rise of the current output signal of the power source is detected and is compared with a reference predetermined value. Thereby when the detected value exceeds the reference value an alarm signal is generated and the number of the disconnected lamps can be determined and displayed.

Pulse width modulated constant current servo driver

Abstract: A method and apparatus for controlling a coil (40) operated hydraulic valve (48) employs a constant current source (36) to consistently control valve response (P o ) irrespective of variations in power supply voltage and coil resistance (R c ). A switching circuit (58) controls the delivery of constant current pulses from the current source (36) to the coil (40) in accordance with a series of pulse width modulated control signals whose duty factors (t 1 /t 2 ) are proportionate to preselected values of hydraulic output pressures (P o ) developed by the valve (48). A voltage regulator circuit (38) provides regulated supply voltage to the constant current source (36) in order to reduce variations in the coil current (I c ) at small pulse widths.

Device for electric monitoring of the level of a liquid in a container

Abstract: A device for electric monitoring of the level of a liquid present in a container, with a temperature-dependent resistance probe which is immersed in the liquid the level of which is to be monitored, a source of constant current connectable, controlled by a timer, to the resistance probe, a circuit, controlled by the timer, for detecting and storing an initial voltage drop on the resistance probe at an initial time and a measurement voltage at a defined time after the connection of the source of constant current, and a circuit for evaluating these voltages by subtraction of the measurement voltage from the initial voltage and if necessary under circumstances inversion of the difference in order to form a display voltage which corresponds to the level. There are provided a resistance probe structure for compensating for the influence of the change in level of the liquid on the display voltage due to thermal expansion as a function of its initial temperature and a computation circuit for compensating for different heat transfers from the resistance probe to the liquid as a function of the initial temperature.

Rapidly-heated periodically-maintained heater for motor vehicle apparatus

Abstract: A heating device for use in motor vehicles to rapidly heat combustion chambers, exhaust gas sensors, catalyzers and other associated apparatus. A resistive heating element is connected in series with a low-impedance measuring resistor and a switch across a power source, while a resistance bridge is formed with the aid of two further resistors. The diagonal bridge voltages are compared in a comparator whose output actuates a control circuit which operates the heater switch. The heater switch also provides the power for the comparator. In a first interval, constant current is applied to the heating element, while the current is pulsed during a second time interval. The switch control pulses may be provided by a free-running oscillator or one whose pulses are synchronized with the undulations of the engine starter current.

A Direct-Reading AC Comparator Bridge for Resistance Measurement at Power Frequencies

Abstract: A current comparator technique for the measurement of resistance at 50-60 Hz with an accuracy of better than 10 ppm is described. The current in the unknown resistor is compared, using the current comparator, to the current in a reference resistor for the inphase component and to the current in a reference capacitor for the quadrature component or phase defect. Six-digit resolution is provided for both components. The bridge is direct reading in either per-unit resistance or conductance. Nominal ratios of 1,2,5,10,20,50, and 100 are available. An auxiliary two-stage current transformer provides extension of the ratio range to 10 000 and also of the maximum applied current to 100 A. The bridge is suitable for measuring resistances from 10 m? to 1 M?.

Current control system for an induction heating apparatus

Abstract: Coil current loading the induction coils of an induction heating apparatus is directly sensed at the input from the tank circuit and the derived feedback current signal is used to control the power supply to the tank circuit be reference to a signal provided manually or automatically under process control. A voltage feedback signal is derived with a transformer from the input to the tank circuit for providing an input to a voltage limiter operative on the current controller when the voltage to the tank circuit exceeds an acceptable limit. A current limiter overrides the current controller to limit the load current by control of the current controller when the load becomes excessive.

Control circuit for the drive current of a laser

Abstract: Control circuit for controlling a laser drive current. In known control circuits certain levels of the optical output signal are kept constant. This renders it difficult to satisfy certain requirements during the life of the laser as regards the linearity of the modulation of the optical output signal. In the described control circuit the intermodulation of two signals present in the modulation signal with substantially constant amplitudes is measured, an error signal which controls a component of the drive current being derived therefrom.

Power Design for Gigabit Josephson Logic Systems

Abstract: An ac power system design in described for powering, at near gigahertz frequencies, 16K Josephson latching logic circuits distributed uniformly over 16 chips. The power system distributes a sinusoidal current waveform from a single source to the many chip quadrants through a tree system of thin-film transformers that have branching secondaries and multiple turn primaries to maintain nearly constant current amplitudes throughout the system and small phase skews at the logic-circuit level. The sinusoidal waveform is clipped on-chip to provide the trapezoidal waveform required by the logic circuits. The ratio of the duration of the up-portion of the trapezoidal half-cycle to the half-cycle period (the logic cycle) is defined as the active duty cycle for the logic. The 16K circuit-power design is capable of providing an 80-percent duty cycle at a 1.7-ns logic cycle while keeping current levels in the system below 300 mA. An approximate expression is derived that predicts that for any power-system design of this type the product of the system size, the highest frequency of operation, and the chip-quadrant current level is a constant.

Method and apparatus for controlling current or power between interconnected power stations

Abstract: A method and apparatus for controlling a current and/or power between interconnected power stations. A deviation from a base load in an active current or power flowing out of a power station and a deviation from a normal value in the terminal voltage of the power station are measured. A linear function of the ratio of the voltage deviation to the active current deviation is obtained, and a product of the active-current to voltage deviation function and an active current flowing out of the power station is calculated, and thus a reactive current is defined by the product. An internal generation current of the power station is controlled so as to coincide substantially with the sum of the current composed of the active current and the reactive current defined above, and other currents of the power station including the internal load current.

Battery-powered transmitter including current control circuit

Abstract: A portable, battery powered transmitter including a current control circuit for controlling the output power of the transmitter over a wide range of variations in battery voltage, rf input power and frequency, and ambient temperature. The transmitter includes an amplifier operative to receive a voltage from the current control circuit and to draw load current from the current control circuit. The load current drawn by the amplifier is limited by the current control circuit to a predetermined maximum value thereby to prolong the mission life of the battery source powering the transmitter.

Transformerless line interface circuit

Abstract: A line circuit includes a fixed resistance feed consisting of a pair of resistors connected in series with a d.c. power source and tip and ring leads of a communication line. A variable current feed includes a current sink and a current source also connected in series with the d.c. power source and the TIP and RING leads. Energizing current flow in the communication line results as the combination of currents passed by the two feeds. A control circuit determines the currents conducted by the current source and current sink and introduces variations in these currents in accordance with signals for transmission along the communication line. Differences between current flows in the variable current feed and current imbalance conditions on the communication line are accommodated by the fixed resistance feed which also determines the terminating impedance for the communication line.

Reference current source circuit

Abstract: A reference current source circuit comprises a current sink including a pair of transistors having different emitter areas and an emitter resistor connected to the emitter of one of the transistors having greater emitter area, and producing sink currents of the same magnitude which is dependent on the emitter area ratio and the resistance value of the emitter resistor and independent of a supply voltage. In order to supply the current sink with the sink currents, there are used two constant current sources to produce constant source currents of the same magnitude greater than that of the sink currents and a current mirror connected to these constant current sources. The current mirror absorbs surplus currents of a magnitude equal to the difference between the magnitudes of the source current and sink current.

Level shift circuit

Abstract: PURPOSE:To stabilize the operation of a level shift circuit easily by making the saturation current value of a diode much greater than the constant current of constant-current supply FET by decreasing the width or thickness of a semiconductor layer constituting the diode less than those of two FETs CONSTITUTION:As a constant-current supply, FET2 serves, and FET1 operates as a source follower with loads of FET2 and diode 3 An input voltage applied to the gate of FET1 is level-shifted by a voltage drip across diode 3 and then outputted from a series-connection point between diode 3 and FET2 In this case, the width or thickness of a semiconductor layer constituting diode 3 is decreased less than those of FETs 1 and 2 to fix the saturation current value of diode 3 much greater than the constant-current value of FET2 Consequently, the operation of a level shift circuit can be stabilized in an extremely-easy method

Integrated circuit FM local oscillator with AFC control and temperature compensation

Abstract: A FM local oscillator circuit suitable for integrated circuit fabrication, the frequency of which responds to a first current component for reducing frequency drift of a tuned frequency as a function of temperature and to a second current component for providing automatic frequency control of said tuned frequency. The circuit comprises a cross coupled differential pair of transistors, adapted to be coupled to a tuned circuit manually tunable over a given frequency range, which exhibit a negative conductance substantially controlled by said first current component for sustaining oscillations over said given frequency range and which further exhibit a variable capacitance controlled by said second current component for providing electronic fine tuning of the oscillator circuit. The emitters of the differential transistor pair are joined and coupled to first and second current sources, the first of which is temperature compensated for generating said first current component and the second of which is selectively controlled by an AFC control signal for generating said second current component.

Detecting method for capacity of battery for automobile

Abstract: PURPOSE:To detect the capacity with high precision even during operation by detecting discharge current of the battery and terminal voltage, calculating internal resistance of the battery, dead short current, etc. based on the detection, and determining the capacity in accordance with prescribed experimental formulas. CONSTITUTION:The maximum discharge current I1 of the battery at the time of start of a crank shaft and the terminal voltage V1 of the battery at that point of time, as well as the minimum discharge current I2 flowing during the rotation at a prescribed angle of the crank and the terminal voltage V2 at that point of time, are detected by a detecting circuit 10 for dead short current IB, detecting circuits 14 and 18 for currents I1 and I2, a detecting circuit 12 for the terminal voltage VB of the battery at the time of discharge and detecting circuits 16 and 20 for voltages V1 and V2. Then, internal resistance (r) and current IS at the time of short-circuit of the battery is calculated through digital operation based on the formulas I and II by an operation circuit 24, and further multiplication of corelative functions A and B settled in compliance with the kind of the battery irrespective of the temperature and density of the liquid of the battery by the experimental formula III which accords well with actual conditions, as well as addition of a similar function C through the intermediary of an addition circuit 30, etc. is conducted, whereby the capacity of the battery is determined. By this constitution, the capacity of the battery can be detected with high precision even during operation.

A High Signal-to-Noise Oscillator for Contactless Measurement of Photoinduced Carrier Lifetimes

Abstract: A wide-band apparatus for contactless measurement of small changes in photoinduced carrier population is described. Since for some phenomena the signals of interest have very low amplitude, and since the generator supplying energy for the measurement is an oscillator loosely coupled electromagnetically to the semiconductor, very-low-noise circuitry is required. Further, sensitivity to minute conductivity changes is enhanced when the oscillation amplitude is made directly proportional to the figure of merit, Q, of the coupled oscillator resonant parallel inductance-capacitance (LC) tank. The circuit to approximate the desired dependence, amplitude = kQ, contains only two field-effect transistors and is basically an oscillator supplied by a constant current rather than by a constant voltage source. Its operation is analyzed via modeling that specifies the output signal as a function of device and circuit parameters; excellent correspondence with empirical data is shown. The oscillator also operates as an infinite impedance detector of its own amplitude; this amplitude is shown to be linearly dependent on carrier concentration over significant ranges. Thus, the oscillator steady-state and transient responses may be directly related to wafer conductivity, induced carrier amplitude, and lifetime. The described apparatus is sensitive to carrier concentration changes of less than 10 1 1 electrons or holes per cubic centimetre of silicon and will provide measurement of lifetimes from a microsecond to several seconds.

Mutual inductance current transducer for AC electric energy meters

Abstract: A mutual inductance current transducer includes a primary winding for direct connection to the current component of an electric energy quantity to be measured by an AC energy meter. A secondary winding is inductively coupled to the primary winding to produce an output signal that is proportional to the time derivative of the current component. The output circuit provides a current responsive input to an energy measuring circuit also receiving a voltage responsive input.

Method for rapidly testing quality of incompletely charged electrochemical cells

Abstract: A method for rapidly testing rechargeable electrochemical cells following assembly which enables the testing of cells to be carried out in a substantially uncharged condition. Cells in the assembly line are energized with a constant current pulse applied to their electrodes via the cell terminals, the current being of sufficient magnitude and duration so as to develop an increased charge voltage between the cell terminals. The charge voltage so developed during the application of the current and while the electrodes of the cell are incompletely charged is then measured and compared with a predetermined zone of acceptable values for cell performance. Preferably, the developed charge voltage is permitted to stabilize prior to measurement. In addition, measurements of open circuit voltage are taken immediately before and after application of the current pulse.

CR Oscillator having constant current charging source

Abstract: A CR oscillation circuit is provided which includes inverters which are connected in series and whose operating current paths between a power source terminal and a ground terminal are connected in series with a constant current source. In certain embodiments, a resistor is connected between the output terminal of one inverter and the input terminal of the first inverter, and a capacitor is connected between the output terminal of another inverter and the input terminal of the first inverter. The CR oscillation circuit further has a constant current source connected in series with the operating current path of said inverters between the power source terminal and the ground terminal. In other embodiments, the resistor and capacitor are connected in parallel and to the input of an inverter.

Consumable electrode type arc welding method

Abstract: PURPOSE:To perform even welding by using the power source which combines the approximately constant current characteristics of small fluctuations in the output current voltage of the power source in a transient state and the approximately constant voltage characteristics and further change to approximately constant voltage characteristics of a short time until a steady state is reached in the neighborhood of the operating point in a steady state CONSTITUTION:A consumable electrode is fed at approximately a constant speed and a power source having the non-linear characteristics wherein the output voltage and current characteristics of the welding power source near the operating point change from approximately constant current characteristics to approximately constant current characteristics is used, so that the operating point in a steady state during welding is held let to exist on the approximately constant voltage characteristics and the operating point having moved depending upon the fluctuations in the arc length or arc voltage during welding is moved along the specified characteristic curves and is converged at the balance point For example, when the operating point moves to P51 upon changing of the arc length owing to disturbance, the operating point moves in the direction of PS-5 on the curve running the point P51 and moves downward on the curve PS-5 from the point P511 and converges at the operation point P50 of a steady state

Electrically held power relay circuit with reduced power dissipation

Abstract: A relay coil circuit with a switching regulator for coil current to maintain, after closing, a sufficient holding current by the inductance of the coil acting as a current source without supply current.