Showing papers on "Inductor published in 1975"

Small antennas

Abstract: A small antenna is one whose size is a small fraction of the wavelength. It is a capacitor or inductor, and it is tuned to resonance by a reactor of opposite kind. Its bandwidth of impedance matching is subject to a fundamental limitation measured by its "radiation power factor" which is proportional to its "effective volume". These principles are reviewed in the light of a quarter-century of experience. They are related to various practical configurations, including flush radiators for mounting on aircraft. Among the examples, one extreme is a small one-turn loop of wide strip, tuned by an integral capacitor. The opposite extreme is the largest antenna in the world, which is a "small antenna" in terms of its operating wavelength. In each of these extremes, the radiation power factor is much less than one percent.

High efficiency switching regulator

Abstract: An improved switching regulator converts an unregulated DC voltage into a regulated DC output voltage and maintains regulation over the entire range from maximum load current through zero load current. The improved regulator employs a plurality of series switching paths connected between the unregulated DC input and a summing node at a filter capacitor output. Each series switching path includes a power switching element, a catch diode and a series inductor. The other end of the summing node is connected through a current limiting circuit to the DC regulated output, and at least a portion of the voltage at the summing node is fed to a voltage error amplifier and used to control the duty cycle of the series switching elements. Feedback from the current limiting circuit can override the voltage error amplifier control should the maximum current limit be exceeded. The switching control means employs pulse-width modulation for adjusting the duty cycle of the series switching elements, and the technique of pulse-width modulation employed in the present invention is of the constant frequency, variable "ON" time variety, as known in the art. The switching element control means utilizes a selecting means whereby different ones of the switching elements in different ones of the series switching paths are sequentially selected such that the selected series switching element is always turned on into a non-conducting inductor and a fully-recovered catch diode so as to minimize or eliminate the power loss associated with switch turn-on; the noise usually associated with switching regulators; and the turn-on transient which is often propagated into the supply line in the switching regulators of the prior art, thereby allowing highly efficient and reliable regulation to be maintained at very low values or even no value of load current.

Superconductive energy storage inductor-converter units for power systems

Abstract: Large magnets with superconductive windings could serve to perform a power system function analogous to pumped storage hydro. A conventional Graetz bridge converter as used in dc transmission provides an ideal interface between the three-phase power system and the superconductive magnet or inductor. Such Inductor-Converter or I-C units, when properly controlled, provide significant power system benefits. Power reversibility is achievable within a few cycles without switching. Power system electromechanical oscillations can be damped effectively. Computer studies reveal that this damping capability may be useful even with smaller inductor sizes when energy storage in large amounts is not the primary objective. In sizes greater than 1,000 MWh, economic studies show promise.

Light generation by an electrodeless fluorescent lamp

Abstract: An electrodeless discharge lamp has an ionizable medium comprising a particular gas composition at a particular pressure within a sealed envelope. Radio frequency electrical power is applied to an induction coil, the magnetic induction field of which is coupled to the medium. For a particular radio frequency, the magnitude of the induction field is selected to maximize the light emitted by the discharge per watt of radio frequency power coupled thereto. The radio frequency is preferably between 3 megahertz and 300 megahertz. In one embodiment, a mixture of mercury vapor and argon is contained within an envelope having an open cylindrical cavity into which the coil fits; the portion of the interior surface of the envelope defining the cavity has a layer of an electrically insulative, ultraviolet reflective material, and the entire interior surface of the envelope has a phosphor layer; radio frequency power at a frequency of about 4 megahertz is applied to the coil by an oscillator having a tuned circuit including the inductor and the discharge.

Inductor for magnetic pulse working of tubular metal articles

Abstract: Disclosure is made of an inductor for magnetic pulse working of tubular metal articles, wherein the coil is composed of flat conductors insulated from one another and manufactured in the form of at least a sector portion of an annular disc helically bent at a pitch that ensures a displacement of a conductor's ends relative to one another by the length of the coil. Said flat conductors are assembled into a multiple helix. On one side, the ends of said flat conductors are arranged in one plane normal to the coil axis and circumferentially spaced relative to one another at equal angles. Due to the change in the inductance from a value equal to the inductance of a portion of a hollow tubular conductor to that of a single-turn inductor whose turn has geometrical dimensions equal to the dimensions of the inductor coil, the inductor of the present invention makes it possible to carry out magnetic pulse working of large-diameter metal articles.

Inductor-capacitor hybrid

Abstract: A 4-terminal component whose characteristics are determined by both inductive and capacitive mechanisms is analysed. Equations and normalised curves are presented which describe the input/output relationships for various load impedances. Experimental verification is reported, and the internal working of the device is described. Attention is drawn to properties and applications of the hybrid.

Electronic ballast for gaseous discharge lamps

Abstract: An electronic circuit for starting and operating gaseous discharge lamps. A DC input is connected to a time-ratio control (TRC) circuit which includes a regulating transistor, a sensing resistor and a coasting inductor connected in series. A flyback diode is connected to the inductor for providing a discharge path for the inductor. The TRC circuit serves to ballast the gaseous discharge lamp. An inverter is connected to the TRC circuit for driving the lamp with square waves. A starting circuit is provided and is connected to one of the lamp electrodes for starting the lamp. A transient protection circuit is provided for the inverter to shunt transients back to the input. A TRC drive and control circuit is connected to the TRC regulating transistor and sensing resistor for controlling the regulating transistor. Power for the circuits which control the regulating transistor, the inverter and the starting circuit is provided by a feedback power supply which is connected in a circuit relationship with the lamp so that it supplies power substantially only while there is operating voltage for the lamp.

Ultrasonic generator drive circuit

Abstract: The ultrasonic generator comprises a transducer which is adapted to vibrate in a fundamental frequency mode and the harmonics thereof in response to a square wave signal which is applied thereto. The transducer is of the piezoelectric type which has a capacitor loading effect. A square wave generator is provided for generating a square voltage wave and driving means comprising high speed switching transistors is responsive to the signal from the square wave generator for driving the transducer with a square wave. The transistors are switchable between conducting and non-conducting states and are connected to the square wave generator so that the transistors are switched in phase opposition to each other. A non-resonant inductor connects the pair of transistors with the transducer to limit current flow and to permit application of the square wave to the transducer. An alternate embodiment utilizes a balancing transformer to eliminate the normal high common mode switching current.

Pulse width modulated voltage regulator-converter/power converter having means for improving the static stability characteristics thereof

Abstract: Instability effects over a wide range of static load current conditions in a conventional pulse width modulated (PWM) voltage regulator-converter/power converter circuit configuration having cascaded LC--LC filter networks are eliminated by replacing an inductor, in the averaging filter section of the voltage regulator-converter with the primary winding of a transinductor and by placing the secondary winding thereof in series with an inductor in the output filter section of the power converter. The aforementioned transinductor, in combination with other elements of the system, is designed and configurated such that the closed-loop stability characteristics approach that of a two pole system while maintaining the superior filtering characteristics of a four pole system.

Stabilized power supplies

Abstract: A constant-voltage transformer for stabilized power supply includes a primary coil and a secondary coil connected across a tuning capacitor. A magnetically continuous magnetic core links both the primary coil and the secondary coil, and a magnetically discontinuous magnetic core links the secondary coil but not the primary coil. Another discontinuous magnetic core may link the primary coil but not the secondary coil, and a compensating coil may be linked by this core only. Preferred designs have an abrupt cut-off at a load current only a little greater than design value, so that a dangerously high current can never be drawn, even into a total short circuit.

Power supply for a microwave magnetron

Abstract: In a microwave energy generating system, a combination of a magnetron which generates microwave energy and an inverter which converts DC voltage to high frequency AC voltage are employed. The magnetron includes a heater-cathode and an anode. The inverter includes a transformer having a gapped ferrite core, a center tapped primary winding which divides the primary into two portions, and at least a first high voltage secondary winding and a second low voltage secondary winding for the magnetron heater, and means for switching current through each winding half alternately at a periodic high frequency rate, substantially above 60 Hz., to produce a high frequency magnetic field in said ferrite core, and means, including inductor means, are provided for providing DC current into said primary winding at said center tap. High frequency high voltage AC from the first secondary is rectified and coupled to the magnetron and high frequency low voltage AC is coupled from the second secondary to the magnetron heater to enable the magnetron to generate microwave energy. The pulsing/nature of the high voltage applied to the magnetron is believed to avoid "mismoding" of the magnetron and a need for a separate heater transformer is avoided. In a further aspect of the invention, the DC applied to the primary winding is obtained from an AC source and rectifier combination.

Computation of capacitor voltage and inductor current sensitivities with respect to initial conditions for the steady-state analysis of nonlinear periodic circuits

Abstract: In previous work, it was shown that the sensitivity of the state variables of a circuit with respect to the initial-state conditions could be used advantageously to determine the steady-state periodic response of an oscillator or periodically forced system. In this paper, a computational technique for computing this sensitivity is presented which does not necessitate the formulation of the state equations so that the algorithm can be implemented into many current circuit transient analysis programs without major changes. The method yields valid results even when the capacitor voltages and inductor currents are not an independent set of state variables.

Remote electrical monitoring of gas activated blood pumps

Abstract: An electrical capacitance measurement system for monitoring at a distance the instantaneous blood volume within the body of an air or gas activated blood pump. Electrical capacitance changes within the pneumatic blood pump frequency modulates an oscillator, and the extraneous capacitances encountered are incorporated as electrical, integral components in oscillator operation. An inductor, placed within or in close proximity to the pump, and the relatively small electrical capacitance within the pump form an oscillator tank which primarily determines oscillator frequency. By thus creating a tank at the site of measurement, active and other oscillator components can be placed at a distance from the pump, and undesirable cable capacitances can conveniently be incorporated as participating feedback capacitors. Preferably, an electrically protective shield is attached to the outside of the pump which electrically shields the pump and which provides a capacitance larger than the sensing capacitance to provide a linear relationship between the sensing capacitance and the sensor output. The Clapp oscillator principle has been employed as it permits the separate location of the sensing, frequency determining tank, and, at the same time it provides high sensitivity for capacitance measurement and adequate long-term stability. The present system is applicable to various types of gas activated blood pumps employed outside or inside the body of humans or animals.

DC powered capacitive pulse charge and pulse discharge battery charger

Abstract: A battery charger receives electrical power from an external source of direct current electrical power. The power is received through a first inductor which supplies it to a second node. First switching means receives the power from the second node and supplies it to a third node. A second inductor receives the power from the third node and supplies it to the battery to be charged through output connector means. Second switching means are connected to the second node and to a capacitor which is connected to the third node so that the second switching means can switch the capacitor between series circuit and parallel circuit configurations with respect to the first and second inductors. A safety circuit is connected to temperature sensing means positioned to sense the temperature of the battery to be charged, to the first node and to the first switching means. The safety circuit causes the first switching means to become nonconductive upon detection of unsafe conditions which may occur when charging. A control circuit is connected to the first node, to the second switching means, and to the output of the battery to be charged. The control circuit is also connected to the temperature sensing means and supplies control signals to the second switching means to repetitiously cause the capacitor to be first charged in parallel circuit through the first switching means and discharged in series circuit with said first and second inductors to pulse charge the battery to be charged and thereafter cause a brief pulse discharge of the battery to be charged with the repetition rate and magnitude of the pulses varying based on the state of charge of the battery to be charged.

Pulsed xenon arc lamp operating circuit

Abstract: A circuit for the repetitively pulsed operation of a xenon arc discharge lamp. A first SCR is responsive to a first control circuit when fired to allow the charging of a capacitor through a first inductor from a DC energy source. A second SCR is responsive to a second control circuit, and when fired connects the capacitor through a second inductor to a lamp to provide an operating current pulse for the lamp. Also, upon firing of the second SCR, the capacitor supplies a voltage pulse to a pulse transformer which in turn generates a high voltage pulse for ionizing the lamp. The first SCR is responsive to its control circuit to be conductive only when the capacitor is discharged and the second SCR is responsive to its respective control circuit to be conductive only when the capacitor is fully charged. In actual operation, one SCR must have been non-conducting for a predetermined time before the other SCR is allowed to become conductive thereby to prevent shoot-through.

Semiconductor switching circuit with transistor switching power loss reduction means

Abstract: The power loss developed in a semiconductor switch during turning on the current flowing from a DC source through a main inductor is reduced by connecting in series between the switch and the main inductor the series combination of a diode and a further inductor, with the diode being poled to pass current from the switch to the main inductor. The parallel combination of a further capacitor and a further diode is connected between a tapping on said further inductor and the junction of said series combination with the semiconductor switch. To reduce the power loss during turning off the current there is connected between the junction of the semiconductor switch and the inductor two parallelled series combinations of diode and capacitor with the elements in opposite order in the branches and the diodes poled in the same direction, the junctions of the capacitors and diodes in the two series combinations being connected through a series diode-inductor combination. The series combination of semiconductor switch and inductor may be one half of a push-pull inverter circuit.

Reactive current compensating apparatus for electric power systems

Abstract: A reactive current compensator for improving the power factor of a multiphase alternating current electric power circuit comprises a bank of fixed capacitors connected to multiphase line terminals in star circuit relation and two multiphase banks of fixed inductors connected to said terminals in parallel circuit relation, one inductor bank being star-connected and the other being ring connected, together with switching means responsive to a characteristic of power circuit current for controlling the magnitude of current in each phase of both inductor banks.

Frequency converter for three phase machines - gives twelve pulse output by use of two inverter stages

Abstract: Undesirable losses and torque modulations can be minimised by using a twelve pulse output. In a frequency converter with an intermediate d.c. stage this is achieved by adding a second output inverter connected via its own smoothing inductor to the output of the supply commutated converter. The inverter sections are arranged to have 30 deg. displacement between output voltages. The output is typically commoned by a choke coil in each phase with a centre tap from each coil feeding the load machine. The system is applicable to any sort of rotating field load.

Semiconductor package having means to tune out output capacitance

Abstract: For shunt tuning the output capacitance of a semiconductor device having an output terminal serially connected to the semiconductor chip through a parasitic inductance within the device envelope, an additional terminal is provided connected through an internal inductor to a point of junction of the output terminal and the parasitic inductance.

Charging circuits using controlled magnetic fields

Abstract: A circuit for charging an electrical storage device, such as a capacitor, from a source of energy via an induction coil interconnected between the source of energy and the storage device. Current from the source of energy builds up a magnetic field within a primary winding of the coil. A sensing circuit detects a desired maximum value of the magnetic field and then operates a switch to disconnect the primary winding from the source of energy. As the magnetic field starts to collapse, a voltage induced in a secondary winding of the coil enables energy stored in the magnetic field to be transferred to the storage device. When a given minimum value of the collapsing magnetic field is then reached, the primary of the induction coil is reconnected to the source of energy to repeat the above cycle. The minimum of the magnetic field is relatively close to the desired maximum, to permit only a partial magnetic field drop before commencing the next cycle. Protection circuits are included to prevent overcharge of the storage device as well as to terminate the charging process when a predetermined amount of charge has been reached.

High voltage pulse generator

Abstract: An improved high-voltage pulse generator has been provided which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of a first one of the rectifiers connected between the first and second of the plurality of charging capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. Alternate circuits are provided for controlling the application of the charging voltage from a charging circuit to be applied to the parallel capacitors which provides a selection of at least two different intervals in which the charging voltage is turned "off" to allow the SCR's connecting the capacitors in series to turn "off" before recharging begins. The high-voltage pulse-generating circuit including the N capacitors and corresponding SCR's which connect the capacitors in series when triggered "on" further includes diodes and series-connected inductors between the parallel-connected charging capacitors which allow sufficiently fast charging of the capacitors for a high pulse repetition rate and yet allow considerable control of the decay time of the high-voltage pulses from the pulse-generating circuit.

Rotor for an electric machine having a cryo-inductor

Abstract: The invention concerns electric rotating machines whose rotor inductor optes at a very low temperature, characterized in that the rotor of these machines comprises a bearer cylinder made of a non-magnetic material inside which a closed cylindrical body for supporting the inductor winding is fixed in a fluid-tight manner so as to form, between the bearer cylinder and the closed cylindrical body, a space subjected to a thorough vacuum. The invention applies more particularly to electric generators with an inductor cooled by liquid helium.

High efficiency ballast system for electric discharge lamps

Abstract: An improved ballast circuit for one or more electric discharge lamps includes a nonlinear variable capacitor connected in series with an iron core inductor and the lamps across the terminals of a source of alternating current. The nonlinear capacitor preferably exhibits a voltage and/or current dependent capacitance characteristic. The use of the nonlinear capacitor improves the crest factor of the lamp current waveform thereby increasing the operating efficiency of the ballast circuit and reducing the size and cost of the iron core inductor.

Resonant circuit using variable capacitance diode

Abstract: A resonance circuit having an inductor, a capacitor and a semiconductor with a junction, and means for applying a signal to the semiconductor junction. The semiconductor junction satisfies the equation: ##EQU1## where C represents the capacitance of the semiconductor junction when a voltage V is applied thereto and the junction of the semiconductor is reverse biased, C' is a constant, and the inductor and capacitor are connected in series.

High efficiency supply circuit for an electric discharge lamp

Abstract: A ballast impedance for an electric discharge lamp comprises an inductor and a capacitor connected in series with the lamp across AC input terminals. The lamp operating voltage is less than 20 percent of the AC supply voltage. The values of L and C are chosen so that the ballast has a net capacitive character and to provide a resonance between 3.5 and 4 times the frequency of the AC supply voltage.

Control system for sensing the air gap between a cutting tool and a work piece

Abstract: OF THE DISCLOSURE A system for sensing the air gap between a cutting tool and a work piece mounted on a machine for the purpose of controlling the traverse feed rate of the machine as contiguity approaches. A drive coil is mounted on the machine.A search coil surrounds the cutting tool in proximity to the air gap and is mutually coupled (M1) to the drive coil. Amutual inductor has first and second coils arranged so that their mutual inductance M2 is variable; these coils are connected in common at one end to a variable inductionless' resistor r. The first coil is connected series aiding with the drive coil, while the second coil is connected in series opposi-tion with the search coil. An a.c. source is connected across the drive coil, first coil and inductionless resistor. The induced voltage across the series combination of search coil, second coil, and inductionless resistor provides an output which is initially nulled by adjusting M2 and r for a selected datum displacement between cutting tool and work piece. The change in induced output voltage .DELTA.e varies in accordance with the mutual inductive M1 which changes as a function of the instantaneous displacement between the cutting tool and the work piece. The induced voltage .DELTA.e is then used to provide an adaptive voltage which serves to vary the traverse feed rate of the machine as required.

Low KVA static AC motor drive

Abstract: A commutation circuit for an inverter has a capacitor which is charged prior to commutation of the inverter from an auxiliary dc power source instead of by the principal dc power supply for the inverter. Polarity of the voltage on the capacitor is reversed prior to start of commutation by a switch that connects a first inductor across the capacitor to establish a first capacitor current path through the first inductor. No portion of thee first capacitor current by which the capacitor achieves its reverse polarity flows through the inverter. After the polarity of voltage on the capacitor has been reversed the capacitor is connected by switching so as to apply reverse polarity voltage to the dc input busses of the inverter. Commutation current then flows through the inverter, but not through the first inductor. A separate inductor is provided for the commutation current, in series with the capacitor and the inverter. The circuit is particularly advantageous for apparatus in which the principal dc power supply provides an adjustable dc voltage, because the energy available from this circuit for commutation is not significantly diminished by adjustment of the principal dc power supply to low voltage levels because the auxiliary dc power supply becomes effective at the low levels.

Rapid warm-up heater circuit

Abstract: An improvement for effecting rapid warm-up of the thermionic cathode means in a color CRT display device utilizing a degaussing circuit including a temperature responsive resistive element in series with the primary winding of an inductive means. A direct operational relationship is established between the degaussing and cathode heater circuits by having the secondary winding of the inductor series coupled therein. Upon simultaneous activation of both circuits, through a common switching means, a transitory surge of current is supplied by the degaussing circuit to the heater circuit, via the common inductor, to effect an accelerated temperature response in the heater.

Automatic load safety cut-out cct - responsive to short-cct or open-cct across working cct element

Abstract: The circuit employs a contactless initiator, connected via a two wire line with an amplifier, across which the load is connected. The failure of one of the working circuit elements of the initiator and/or the amplifier and/or the load, causes a warning signal to be initiated, and the load is cutout. The initiator preferably comprises an oscillator with a transistor whose base emitter path includes a parallel resonance circuit, with a further parallel capacitor and inductor in the transistor emitter-collector path, a resistor being connected between the two capacitors and the two inductors.

Regulating electric power circuit arrangement

Abstract: The switching circuitry topology is arranged so that the transistors operate in a 1E mode, that is, the voltage across the switching transistors is no greater than the input voltage (E) and at the same time the noise voltage normally generated in regulating circuit arrangements employing transistor switching is greatly reduced. A filter inductor in the primary switching circuit protects the switching transistors from sudden current changes during overload and enables operation of the transistors below the 2E mode. Power is regulated by pulse width control of the switching transistors. One pair of switching transistors is arranged to control the direction of current through the transformer primary winding. Another pair of transistors is arranged for controlling the current in accordance with the width of applied switching pulses. The switch topology also is arranged so that no current ever attempts to flow in the reverse direction through a previously conducting primary circuit diode, hence the rectifying elements are never snapped off, and the less desirable reverse recovery effects are eliminated. Primary-to-secondary circuit isolation is afforded with interchangeable transformer coupling and optocoupling components which also improve immunity to noise.