Double-ended (i.e., Push-pull), Separately-driven Type Patents (Class 363/24)
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Patent number: 5006972Abstract: The invention converts the voltage output of a DC source to a higher voltage. A germanium transistor start-up circuit receives a DC supply voltage input and includes an astable multivibrator which produces a square wave voltage output that is transformed to a substantially DC steady-state voltage output by a transformer and a capacitor. This elevated voltage is provided to an oscillator circuit which provides two square wave outputs. Each output is provided to an array of invertors operably coupled to an array of field effect transistors. The transistors are operably coupled to a power transformer. The square wave outputs of the power transformer are full wave rectified to provide a DC output having a higher voltage than the system input voltage. The power transformer also provides another full wave rectified voltage which disables the start-up circuit to eliminate parasitic energy losses attributable to its continued oscillation.Type: GrantFiled: September 4, 1990Date of Patent: April 9, 1991Assignee: The United States of America as represented by the Secretary of the NavyInventors: Russell E. Hammond, John L. Henry
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Patent number: 4980813Abstract: A power converter is provided with a split primary current fed push pull topology. An inductor connects the primary windings. Controllable switches provide alternate circuits from the dc source inputs through each of the primary windings and the inductor. Clamping diodes connect the ends of the inductor to the dc source inputs opposite to those provided by the controllable switches. The clamping makes cross conduction unnecessary. Separate duty cycle control is provided in each primary circuit.Type: GrantFiled: December 21, 1989Date of Patent: December 25, 1990Assignee: Northern Telecom LimitedInventor: Mark R. Wells
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Patent number: 4969078Abstract: A push-pull transformer of a push-pull current-fed DC-DC converter is arranged so that the inductance of the primary side of the transformer diminishes equivalently, thereby reducing a conversion loss attributable to a distributed capacitance of the transformer. To equivalently reduce the inductance of the primary side, for instance, a gap is formed in the core of the transformer and/or an inductor is connected in parallel to any one of the windings of the transformer.Type: GrantFiled: August 15, 1989Date of Patent: November 6, 1990Assignee: Nippon Telegraph and Telephone CorporationInventors: Katsuhiko Yamamoto, Satoshi Ohtsu, Takashi Yamashita
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Patent number: 4961128Abstract: A unique multi-output isolated buck DC-DC converter system is disclosed. The converter system has non-pulsating input and output current waveforms. The converter can be adapted to two- or three-bobbin integrated-magnetic embodiments, or in discrete-magnetic form. One embodiment of the converter comprises capacitor means joined at one end to a first common core inductor and joined at its opposite end to a second common core inductor; and switch means having a duty cycle, for alternately joining an output lead to one end of the capacitor means and to the opposite end of the capacitor means, such that a voltage proportional to "VD" is produced at the output lead when a DC voltage "V" is applied across opposite ends of the first and the second common core inductor.Type: GrantFiled: December 28, 1988Date of Patent: October 2, 1990Assignee: Zenith Electronics CorporationInventor: Gordon E. Bloom
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Patent number: 4959765Abstract: A quasi-resonant DC to DC converter having zero-current and zero-voltage switching includes a transformer with primary and secondary windings, and periodic switching means connected in series with the primary winding. The converter further includes an input capacitor parallel to the transformer's primary winding and an output capacitor parallel to the secondary winding. The topology of the converter is determined by selecting an input capacitor having a capacitance much lower than the output capacitor, by selecting the resonance period of a circuit including the input capacitor and the overall series inductance of the transformer to be shorter than the ON period of the periodic switching means, and by selecting the resonance period of a circuit including the overall parasitic capacitance, referred to the primary side of the transformer and the periodic switching means, and the magnetizing inductance of the transformer to be shorter than the OFF period of the periodic switching means.Type: GrantFiled: February 22, 1989Date of Patent: September 25, 1990Assignee: Agence Spatiale EuropeenneInventor: Alan Weinberg
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Patent number: 4937729Abstract: A chopper power supply includes a transformer having first and second primary winding segments as well as first and second secondary winding segments respectively associated with the first and second primary winding segments. First and second switching transistors respond to a control source so that the first transistor connects the first primary winding segment to first and second opposite polarity terminals of a DC power supply at a time mutually exclusive from the time the second primary winding segment is connected to the DC terminals via the second transistor and vice versa. Each of the secondary winding segments includes first and second portions disposed on opposite sides of the primary winding segment associated with the secondary winding segment. The portions of the first secondary winding segment are connected in series with each other and coupled to the first primary winding segment so that voltages induced in the portions of the first secondary winding segment add together.Type: GrantFiled: May 17, 1989Date of Patent: June 26, 1990Assignee: Bull S.A.Inventors: Jean Gadreau, Andre Pascal
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Patent number: 4905136Abstract: The output of an AC power source is converted into DC power through a rectifying stack and an electrolytic capacitor and this DC power is input to a chopper circuit, which includes a first switching element, flywheel diode and a coil. The chopper circuit adjusts the value of the power by changing the duty ratio of the first switching element. The output of the chopper circuit is supplied to an inverter circuit and is applied at the center tap of the primary winding of a transformer. The inverter circuit is of a voltage-oscillating type which includes the transformer, a capacitor and second and third switching elements. As the second and third switching elements are alternately switched on, the inverter circuit converts the received DC power into AC power as its output.Type: GrantFiled: November 29, 1988Date of Patent: February 27, 1990Assignee: Kabushiki Kaisha ToshibaInventor: Shigeru Tanaka
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Patent number: 4845606Abstract: A high frequency matrix transformer comprises a plurality of interdependent magnetic elements interwired as a transformer. The various component parts of the high frequency transformer are arranged and interwired to provide a transformer having very low leakage inductance and very good coupling from the primary to the secondary. The high frequency matrix transformer is particularly well adapted for transformers requiring high equivalent turns ratios, high frequency, high power, and high dielectric isolation. It can have a plurality of parallel secondaries, which can source current to parallel rectifier circuits with current sharing. It can also have a plurality of parallel primary circuits, which also will current share, to balance the load between source switching circuits, or to provide dual input voltage capability (i.e., 120/240 volts). The high frequency matrix transformer tends to be spread out, and can be very flat, making it eaasy to ventilate or heat sink.Type: GrantFiled: April 29, 1988Date of Patent: July 4, 1989Assignee: FMTT, Inc.Inventor: Edward Herbert
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Patent number: 4823249Abstract: A high frequency DC to DC converter having at least two phase differentiated pulsed voltage sources, utilizes two phase differentiated unidirectional power flow resonant circuits to permit multiple quasi resonant operation of the converter and thereby gain the benefit of lowered EMI, high efficiency, lowered component stress and increased power throughput.Type: GrantFiled: April 27, 1987Date of Patent: April 18, 1989Assignee: American Telephone and Telegraph Company AT&T Bell LaboratoriesInventor: John D. Garcia, II
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Patent number: 4811185Abstract: A DC to DC power converter having first and second input terminals and an output terminal for providing an output voltage at the output terminal which is at a potential halfway between a DC potential applied by a DC power supply across the first and second input terminal is disclosed. The converter comprises first and second switches connected at a switch junction in series across the first and second input terminals, first and second series-coupled diodes coupled at a diode junction across the first and second input terminals in reverse-bias relationship with respect to the DC potential applied across the first and second input terminals, a transformer comprising two windings inductively linked and having first and second ends and a center-tap, the ends coupled between the switch junction and the diode junction and the center-tap coupled to the output terminal and means for alternately switching the first and the second switches at an equal duty factor.Type: GrantFiled: October 15, 1987Date of Patent: March 7, 1989Assignee: Sundstrand CorporationInventors: Alex Cook, Sampat S. Shekhawat
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Patent number: 4788451Abstract: An electronic AC voltage stabilizer using a class B amplifier output stage which is fed by a full-wave rectified sinewave voltage. The input voltage to (the phase inverter of) the class B amplifier output stage is kept in phase with the aforesaid sinewave voltage, which causes the power losses in the output stage to be very low. As compared to other electronic AC stabilizers, the apparatus according to the invention offers high efficiency and simplicity. The AC stabilizer can easily be converted into a true uninterruptible power supply (UPS) by adding a battery which through a battery interface circuit connects the battery voltage, after it has been appropriately converted into a full wave rectified sinewave voltage, to the push pull amplifier output stage when a power network fails.Type: GrantFiled: September 8, 1987Date of Patent: November 29, 1988Inventor: Hindrik Stoet
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Patent number: 4783795Abstract: An X-ray generator system has first and second switching devices such as transistors which are complementarily turned on and off to intermittently apply a DC voltage to the primary winding of a transformer for thereby inducing a high voltage across secondary windings of the transformer for enabling an X-ray tube to emit X-rays. The X-ray generator has a control mode in which the first and second switching devices are simultaneously turned on immediately before they start being complementarily turned on and off, for allowing the high voltage to have a sharply rising positive-going edge.Type: GrantFiled: January 28, 1987Date of Patent: November 8, 1988Assignee: Kabushikigaisha ToshibaInventor: Mitsuru Yahata
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Patent number: 4748311Abstract: The invention relates to an inverter with a direct-voltage source and a chopper section, the chopper section having push-pull switching at a frequency f.sub.0. A parallel tuned circuit, the resonant frequency of which is 2f.sub.0 is provided between the direct-voltage source and the chopper section.Type: GrantFiled: February 27, 1987Date of Patent: May 31, 1988Assignee: Leybold AktiengesellschaftInventors: Friedrich-Werner Thomas, Johann Sturmer
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Patent number: 4747035Abstract: A device for isolating an electrical instrument from an input voltage signal at a floating potential. The device includes a transformer with a center-tapped primary winding, a center-tapped secondary winding and a core magnetically coupling the primary and secondary windings. The input voltage signal is applied to an input terminal coupled to the center tap of the primary winding. A modulator circuit is connected to the primary winding for alternately applying the input voltage signal to opposite sections of the primary winding by means of FETs, or the like, isolated from a control circuit by a transformer, the control circuit alternately switching the modulator circuit at a suitable modulating frequency.Type: GrantFiled: December 22, 1986Date of Patent: May 24, 1988Inventor: Howard H. Bobry
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Patent number: 4739461Abstract: A power supply device capable of supplying high DC voltages of positive and negative polarities has a transformer having a primary coil and two secondary coils. A DC current supplied to the primary coil is switched to generate voltages in the secondary coils. These voltages are rectified and smoothed in mutually opposite polarities, and the output voltages are obtained by summing the rectified and smoothed voltages.Type: GrantFiled: September 3, 1986Date of Patent: April 19, 1988Assignee: Canon Kabushiki KaishaInventors: Shunichi Komatsu, Koji Suzuki
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Patent number: 4737899Abstract: A very high voltage stabilized power supply device for a pulse radar system, in particular an airborn radar, which comprises a primary winding connected in a series with an electronic power commutation switch actuated at the recurrence frequency of the pulses produced by the radar, or at a multiple frequency of the recurrence frequency, to the terminals of a rectified and filtered voltage supply source. The primary is wound around an inductive element on which are wound a plurality of secondary windings with a primary-secondary winding transformation ratio equal to unity. Each secondary winding is connected in series to a diode with a filter capacitor in parallel. The outputs of the secondary circuits are connected in series so that their voltages accumulate at the output of the power supply unit. Several modules of this type may be used, with their commutating elements actuated on a staggered basis.Type: GrantFiled: December 29, 1986Date of Patent: April 12, 1988Assignee: Electronique Serge DassaultInventor: Gerard Lorec
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Patent number: 4736284Abstract: In a switching power supply circuit, a forward converter includes first to third switching transistors and a switching transformer having first and second primary windings. The first to third switching transistors are connected via series-connected first and second primary windings to a high voltage DC source. While the first to third transistors are simultaneously turned off, magnetic fluxes induced in the switching transformer are completely reset.Type: GrantFiled: December 29, 1986Date of Patent: April 5, 1988Assignee: Kikusui Electronics Corp.Inventors: Masaaki Yamagishi, Masahiko Shimizu
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Patent number: 4727465Abstract: This circuit, for reliably driving a load both in DC and AC mode with a low dissipation, comprises a pair of MOS power transistors, in a push-pull configuration, and a bootstrap circuit including a bootstrap capacitor placed between the source of the upper MOS transistor and a reference voltage point, through a first switch. A second switch is arranged between the supply line and the gate of the upper MOS transistor, while a third switch is arranged between the gate of the upper MOS transistor and the point common to the first switch and the bootstrap capacitor. During DC operation, the switches are open or closed in order to allow for the connection of the gate of the MOS power transistor to the supply voltage. During AC operation, the switches are controlled thereby, alternately the capacitor is charged at the voltage of the reference voltage point and the upper MOS transistor is held at a gate-to-source voltage sufficient to feed the load.Type: GrantFiled: August 18, 1986Date of Patent: February 23, 1988Assignee: SGS Microelettronica S.p.A.Inventors: Carlo Cini, Claudio Diazzi, Domenico Rossi
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Patent number: 4707776Abstract: In the primary circuit of dc-to-dc converter or a dc-to-ac converter, transistor switching units are associated with two primary windings of a transformer. The transistor switching units each control the flow of current through an associated winding. The first transistor is activated by apparatus that alternatively applies and removes activation signals to the transistor and consequently allows conduction through the transistor and the associated winding. The second transistor receives activation signals from a third primary winding and causes conduction of current through the associated primary transformer winding. The activation signal from the third winding, causing the second transistor to be conductive, is the result of interruption of current in the first primary transformer winding. The activation signals produced by the third primary transformer winding is removed when the first transistor is activated and current is flows in the first primary winding.Type: GrantFiled: November 12, 1986Date of Patent: November 17, 1987Assignee: Burr-Brown CorporationInventor: Thomas A. Somerville
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Patent number: 4706181Abstract: A power converter is provided with a pair of auxiliary windings coupled to the primary windings of the output transformer which serve as energy choke windings. An additional pair of choke windings are coupled between the input of the converter to a common terminal of the primary winding. These choke windings prevent excess voltage from appearing across the switching devices of the converter during the turn-off portions of the cycle.Type: GrantFiled: February 2, 1987Date of Patent: November 10, 1987Assignee: Unisys CorporationInventor: Larry N. Mercer
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Patent number: 4706177Abstract: A DC-AC inverter includes a bridge converter for converting an input DC into an output AC signal which uses field-effect transistors in the bridge circuit. The characteristics of the field-effect transistors enable the bridge converter to temporarily supply power in significant overload conditions. A DC-DC converter may also be included between the DC power source and the bridge converter to provide voltage boosting, when required. Field-effect transistors are also included in the DC-DC converter for power switching. The duration and amount of overload current output by the bridge converter is monitored and when an overcurrent condition beyond a predetermined amount or duration is detected, the bridge converter is disabled. The bridge converter is reenabled at a predetermined time thereafter.Type: GrantFiled: November 14, 1985Date of Patent: November 10, 1987Inventor: Elliot Josephson
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Patent number: 4695934Abstract: A resonant converter feeds five load circuits while maintaining excellent voltage regulation. The power converter features a non-bifilar wound transformer with the resonant capacitors serving the dual function of suppressing diode voltage switching transients while forming the resonant circuit in conjunction with the transformer. Overcurrent circuit protection is also provided.Type: GrantFiled: May 13, 1985Date of Patent: September 22, 1987Assignee: General Electric CompanyInventors: Robert L. Steigerwald, Keku M. Mistry
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Patent number: 4689731Abstract: An inverter for producing A.C. from a source of D.C. electric power. The power circuit includes a power transformer with the current flow through the two halves of the primary winding 16 being controlled by a pair of power MOSFETs. A gate driver circuit which includes a driver transformer produces control signals which are substantially 180.degree. out of phase across the center tapped secondary winding of the driver transformer. A pair of fast-off, slow-on coupling circuits consisting of a diode connected in parallel with a resistor couples gate control signals to the gates of the power MOSFETs. Each coupling circuit is effectively in series with one of a pair of current limiting off-time setting resistors, the latter being connected in series with the two halves of the primary winding of the gate driver circuit control transformer.Type: GrantFiled: August 7, 1986Date of Patent: August 25, 1987Assignee: Honeywell Inc.Inventors: Charles S. Walker, Jay W. Atherton, Gerald W. West
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Patent number: 4684820Abstract: A circuit for generating a relatively high voltage, fast rise time pulse for a load. The circuit includes first and a second pulse-forming networks with each network including shunt capacitance and series inductance, and with each network having an input end and an output end. The circuit also includes first and second charging circuits with one charging circuit connected to the input end of a respective one of the pulse-forming networks. Additionally, the circuit of the present invention includes switch means connected across the input end of the first network to short-circuit the input end of the first network when the switch is closed so that after interconnection of the network output ends with one another and with the load and after the capacities of the networks have been charged, operation of the switch results in a pulse of high voltage to be developed across the load due to superimposition of voltage waves.Type: GrantFiled: February 13, 1985Date of Patent: August 4, 1987Assignee: Maxwell Laboratories, Inc.Inventor: Vance I. Valencia
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Patent number: 4675796Abstract: An integrated magnetic assembly for use in the direct current output circuit of a high frequency electronic switching power supply, comprising magnetic core sections for the output transformer and inductor windings and a common magnetic core segment completing the magnetic flux paths for the transformer and inductor windings. An auxiliary winding on one or both of the core sections is supplied with energy from the capacitor of a snubber circuit connected across the primary side of the magnetic output circuit. This auxiliary winding is magnetically coupled to the secondary side of the magnetic circuit to transfer energy to the power supply output during a portion of the switched current cycle.Type: GrantFiled: May 17, 1985Date of Patent: June 23, 1987Assignee: Veeco Instruments, Inc.Inventors: George A. Gautherin, Sol Greenberg
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Patent number: 4674019Abstract: A transformer-coupled two-inductor buck converter is provided which comprises a series input circuit including an input inductor, a capacitor and a grounded inductor. The input and grounded inductors are wound so that a source of d.c. input voltage can be connected across positive polarity outer ends thereof. A transformer is provided for coupled the input and output circuits of the converter. When a switching transistor in the input circuit turns on, input current conducting through the input inductor joins with current being dragged out of the grounded inductor and through the capacitor to conduct through the primary winding of the transformer and couple to the secondary winding for delivery as output current to the load. An output winding coupled to the grounded inductor is connected by a switching diode to the load.Type: GrantFiled: April 16, 1986Date of Patent: June 16, 1987Assignee: Keller-Mullett TechnologyInventor: Robert M. Martinelli
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Patent number: 4669037Abstract: A device for isolating an electrical instrument from an input voltage signal at a floating potential. The device includes a transformer with a center-tapped primary winding, a center-tapped secondary winding and a core magnetically coupling the primary and secondary windings. The input voltage signal is applied to an input terminal coupled to the center tap of the primary winding. A modulator circuit is connected to the primary winding for alternately applying the input voltage signal to opposite sections of the primary winding by means of photo FETs or the like for alternately switching the modulator circuit at a suitable modulating frequency. A demodulator circuit is connected to the secondary winding for alternately connecting each end of the secondary winding to a common return point to demodulate the output signal from the center tap of the secondary winding by means of FETs or the like.Type: GrantFiled: February 1, 1985Date of Patent: May 26, 1987Inventor: Howard H. Bobry
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Patent number: 4661896Abstract: A high voltage power supply system includes a DC-to-DC converter for producing a DC low voltage, a DC-to-AC inverter connected to a step-up transformer for producing an AC high voltage by transforming an AC low voltage obtained from the DC low voltage, and an inverter controller for controlling an operation time period of the DC-to-AC inverter longer than that of the DC-to-DC converter. Since a residual charge stored in a capacitor of the DC-to-DC converter is rapidly discharged by lengthening the operation time period of the DC-to-AC inverter, an unwanted AC high voltage is induced at a secondary winding of the step-up transformer.Type: GrantFiled: June 30, 1986Date of Patent: April 28, 1987Assignee: Kabushiki Kaisha ToshibaInventors: Hiroyoshi Kobayashi, Kenji Honda
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Patent number: 4639844Abstract: A resonant current-driven power source is disclosed. Preferably, the power source is a DC to DC converter regulator including a inductor and capacitor electrically coupled to one another and an input inverter which converts an input DC voltage into an AC voltage having substantially no DC component and applies the AC voltage across an LC circuit in a manner which causes the inductor and capacitor of the latter to resonate with one another whereby an AC voltage appears across the capacitor. An output circuit converts the AC voltage appearing across the capacitor into a DC output voltage. A control circuit is provided for controlling the operation of the inverter circuit in a manner which controls the magnitude of the output voltage. The inverter circuit also includes a step-up transformer for increasing the magnitude of the AC voltage across the LC circuit to a value many times greater than the input DC voltage.Type: GrantFiled: August 6, 1984Date of Patent: January 27, 1987Assignee: Venus Scientific Inc.Inventors: George C. Gallios, Charles Lien
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Patent number: 4638176Abstract: An uninterruptible power supply provides for input sinewaves of an AC utility to be separated by diode rectifiers to apply positive half sinewaves on a plus d.c. line and negative half sinewaves on a minus d.c. line. A battery-powered high-frequency inverter forming a part of the power supply includes a full wave diode rectifier for applying bursts of positive going pulses having sinusoidally varying duty cycles on a plus d.c. bus and bursts of negative going pulses having sinusoidally varying duty cycles on a minus d.c. bus. The plus d.c. line and the plus d.c. bus are joined and connected by a first synchronous switch to a common junction and the minus d.c. line and the minus d.c. bus are joined and connected by a second oppositely phased synchronous switch to the same common junction. The inverter is driven by bursts of pulses having sinusoidally varying duty cycles generated by comparing the amplitudes of feedback output half sinewave signals and reference half sinewave signals.Type: GrantFiled: August 1, 1985Date of Patent: January 20, 1987Assignee: Mullett Associates, Inc.Inventor: Robert M. Martinelli
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Patent number: 4608627Abstract: A nondissipative current distribution circuit for a power source, such as magnetohydrodynamic generator, that delivers its output current through a first plurality of positive electrodes and a second plurality of negative electrodes (including plural positive and negative electrode pairs) and provides a predetermined current distribution among the electrodes, is described, and comprises a transformer including first and second windings, the second winding including means for connection to a load, the first winding having plural adjustable taps intermediate its ends, an inductor connected at one end to one end of the first transformer winding and at the other end to a plurality of capacitors connected respectively to each electrode, and a first plurality of silicon controlled rectifiers connected, respectively, between each positive electrode and a tap or the second end of the first transformer winding, and a second plurality of silicon controlled rectifiers connected, respectively, between each negative electType: GrantFiled: June 20, 1985Date of Patent: August 26, 1986Assignee: The United States of America as represented by the Secretary of the Air ForceInventor: James F. Holt
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Patent number: 4607322Abstract: A snubber circuit for protecting power switches which modulate the flow of power through an inductive element in a power converter, such as a main primary winding of a transformer, includes a snubbing capacitor and a first switch which is operable to connect the snubbing capacitor to a power switch. A second switch is operable to connect the snubbing capacitor to an auxiliary primary winding of the transformer. The first and second switches are operated so that immediately prior to turn-off of the power switch, the capacitor is connected thereto to store the turn-off reactive power caused by turn-off of the power switch. The first switch is then opened and the second switch closed to couple the reactive power to the auxiliary primary winding to improve the efficiency of the converter.Type: GrantFiled: September 17, 1984Date of Patent: August 19, 1986Assignee: Sundstrand CorporationInventor: Eric A. Henderson
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Patent number: 4591964Abstract: The invention relates to a method and an apparatus for secure interruption of the supply of electric power from e.g. a low-frequency source (1) to a signal lamp (2) which when alight announces permission for a train to pass. The output voltage (a) of the source (1) is chopped by a chopper device (4) to a high-frequency alternating voltage (e,f) in response to a high-frequency input signal (b) to the chopper device (4) and is transferred from the primary to the secondary side of a transformer (5,6) as well as being rectified and filtered to form a voltage (k) applied to the signal lamp (2), said voltage (k) having a wave form corresponding to the wave form of the output voltage (a) of the source (1) and which is securely interrupted by interrupting the input signal (b) to the chopper device (4).Type: GrantFiled: September 30, 1983Date of Patent: May 27, 1986Assignee: Telefonaktiebolaget LM EricssonInventor: Clas A. Kemstedt
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Patent number: 4553070Abstract: An electronic ballast for a discharge lamp (8) for restricting and stabilizing the lamps current. The ballast comprises a high frequency oscillator for connection to a D.C. supply which consists of two transistors (1,2) connected in series, with a base drive transformer (3) coupled between them to bring the transistors (1,2) into alternating phase operation. A resonance circuit connected in series with the primary winding (4) of the transformer (3), comprises an inductor (7), resonance capacitors (10 and 11) and a capacitor (9) coupled in parallel with the lamp (8). The lamp (8) is, in turn, connected in series with the resonance circuit. In addition, a filter capacitor (c) having a high charging ability is coupled between the terminals of the D.C. supply. The resonance capacitors (10 and 11) are connected in series between the terminals of the D.C.Type: GrantFiled: July 6, 1982Date of Patent: November 12, 1985Assignee: Oy HelvarInventors: Martti Sairanen, Matti Virta
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Patent number: 4553199Abstract: A high frequency power supply device has an inverter circuit and an output circuit connected thereto. The inverter circuit includes a diode and a capacitor being connected in parallel to an output side of a switching transistor. A drive input voltage of the switching transistor has a dead time during which a collector voltage thereof is inverted by resonance between the capacitor and a circuit inductance of the device. The switching transistor is turned on when the diode is turned on, thereby reducing the switching loss of the switching transistor. The output circuit includes a ferroresonant circuit or a magnetic amplifier circuit which has a saturable inductor.Type: GrantFiled: October 13, 1983Date of Patent: November 12, 1985Assignee: Tokyo Shibaura Denki Kabushiki KaishaInventors: Koosuke Harada, Katsuaki Murata
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Patent number: 4550364Abstract: A low voltage switching power supply designed to be compact and efficient for use with very high speed integrated circuits (VHSIC) has an innovative output transformer. Designed for use at greater than 50 KHZ (typically 100 KHZ) the transformer is box-like in shape of high permeability ferrite material having one to four rectangular channels containing the primary and secondary winding. The secondary is electroplated copper with very low resistance while the primary is copper tape of some sixteen nominal turns. The power capability is 500 Watts with the output at 5 Volts DC or less and has an efficiency of greater than 98 percent. Up to three transformers can be paralleled to give a total output power of 1500 Watts.Type: GrantFiled: June 5, 1984Date of Patent: October 29, 1985Inventor: William S. Shaw
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Patent number: 4542440Abstract: A push-pull converter has transistor power switches which conduct alternately to connect a DC source with the primary windings of an output transformer. A turn-off snubber circuit is connected with each power switch. When a power switch is turned on, snubber current pulses flow in the circuits connected with both switches. A switch current sensor circuit has a current transformer with an output winding inductively coupled with each of the conductors connected between the power switches and the primary windings of the output transformer. The snubber current pulses through the conductors are 180.degree. out of phase and are suppressed in the current transformer output. The switch current signal from the secondary of the current transformer is free of snubber current pulses and is used in a flux balance circuit and in a pulse-by-pulse current limiter.Type: GrantFiled: November 2, 1983Date of Patent: September 17, 1985Assignee: Sundstrand CorporationInventors: P. R. K. Chetty, John Dhyanchand, Pierre Thollot
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Patent number: 4443840Abstract: A direct voltage-direct voltage converter including: a transformer having at least one primary winding and at least one secondary winding; first and second electronic switches connected to the primary winding; a rectifier unit connecting the secondary winding to a load; and switch control circuitry connected to the electronic switches for closing the switches periodically and in alternation at a selected repetition rate in response to pulses produced by a clock pulse generator, for applying a direct voltage across the primary winding and periodically reversing the polarity of that direct voltage across the primary winding.Type: GrantFiled: September 28, 1982Date of Patent: April 17, 1984Assignee: Licentia Patent-Verwaltungs-GmbHInventors: Klaus H. Geissler, Karl-Heinz Hubner
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Patent number: 4439822Abstract: A method and apparatus is disclosed for detecting an impending saturation in nonlinear magnetic material for particular operating conditions, such as in a core of a power transformer T.sub.1 of a switched-mode converter, in response to a varying magnetic field in a principal direction induced by a drive current through its primary winding with its axis aligned in the principal direction. A transverse flux sense winding (20) is used in monitoring the rate of change of flux density of a transverse magnetic field to produce a voltage proportional thereto. That voltage is compared in a comparator (22) with a predetermined threshold voltage characteristic of impending saturation of the core. The output of the comparator is used for controlling drivers (25) to prevent saturation of the switched-mode converter bias switching the drivers off alternately when the sensed voltage reaches the predetermined threshold set at the comparator (22).Type: GrantFiled: March 26, 1982Date of Patent: March 27, 1984Assignee: California Institute of TechnologyInventor: Alan G. Cocconi
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Patent number: 4347560Abstract: In a square wave generator for the supply of power to a plurality of electric units the advantages of current controlled and voltage controlled generators may be combined by the provision of two output transformers (T1 and T2) whose primary windings are connected in parallel through diodes (D5 and D6), which in case of overloading are blocked by the voltage of a capacitor which itself is connected through a diode which is also blocked by said voltage.Type: GrantFiled: March 20, 1981Date of Patent: August 31, 1982Assignee: Christian Rovsing A/SInventor: Ole S. Seiersen
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Patent number: 4336587Abstract: A turn-off loss reduction network is applied to the power transistors of a double-ended inverter circuit to reduce power dissipation therein. A switched resonance discharge circuit is utilized to discharge the storage capacitor of the turn-off loss reduction network. Dissipation during discharge is eliminated by including an energy recovery circuit in the discharge network which is operative to return the energy to the input voltage source of the inverter. The gate discharge circuit includes a gated resonant discharge path with an inductive storage medium having a secondary winding or otherwise coupled to return the energy to the input voltage source.At the beginning of the conduction cycle of the power switching transistor, a gate is enabled which allows the capacitor to discharge into the inductive storage medium. When the discharge current reaches its peak value, the gate is disabled, and the energy stored in the inductive medium is discharged to the source by flyback action.Type: GrantFiled: June 29, 1981Date of Patent: June 22, 1982Inventors: Charles W. Boettcher, Jr., Robert E. Schroeder
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Patent number: 4280174Abstract: A DC-DC converter for converting a primary DC voltage to a secondary DC voltage comprises a transformer with a primary winding and a secondary winding each wound on a ferromagnetic core, a primary DC voltage power source, a plurality of switching transistors connected between said DC voltage power source and the primary winding of the transformer, means for controlling the status (ON or OFF) of the transistors so that an alternate current or an intermittent current in the predetermined direction flows from the DC power source to the primary winding of the transformer, a rectify/smoothing circuit connected between the secondary winding of the transformer and a load, and said primary winding of the transformer having a center tap which is connected to one end of the DC voltage power source through a capacitor.Type: GrantFiled: January 17, 1980Date of Patent: July 21, 1981Assignee: TDK Electronics Co., Ltd.Inventor: Eijiro Sonda
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Patent number: 4276588Abstract: In a push-pull converter, switching transistors are protected from peak power stresses by a separate snubber circuit in parallel with each comprising a capacitor and an inductor in series, and a diode in parallel with the inductor. The diode is connected to conduct current of the same polarity as the base-emitter junction of the transistor so that energy stored in the capacitor while the transistor is switched off, to protect it against peak power stress, discharges through the inductor when the transistor is turned on, and after the capacitor is discharged the energy now stored in the inductor discharges through the diode. To return this energy to the power supply, or to utilize this energy in some external circuit, the inductor may be replaced by a transformer having its secondary winding connected to the power supply or to the external circuit.Type: GrantFiled: June 22, 1979Date of Patent: June 30, 1981Inventors: W. T. McLyman, Robert A. Frosch
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Patent number: 4254459Abstract: A direct current-to-direct current converter is disclosed wherein a saturable core oscillator provides squarewave alternating current signals to the bases of two transistors of a class B push-pull amplifier such that the two transistors are alternately biased into conducting states. Each transistor controls the current in one section of a center-tapped primary winding of a transformer such that the alternation of conduction between transistors produces an alternating flux density in the core of the transformer and direct current is provided by rectifying and filtering the alternating current induced thereby in the secondary winding of the transformer.Type: GrantFiled: January 8, 1979Date of Patent: March 3, 1981Assignee: JMJ Electronics Corp.Inventor: James M. Belson
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Patent number: 4238810Abstract: A control circuit for an electrical precipitator having a high voltage transformer with a bridge rectifier between the secondary of the transformer and the high voltage precipitator electrodes. The control circuit includes a pair of oppositely poled main thyristors in the primary circuit with a firing arrangement to trigger the main thyristors to maintain desired conditions at the electrodes. The primary circuit does not require a current limiting reactor to limit primary current when a spark discharge takes place at the electrodes. A pair of auxiliary thyristors are each connected in series with a capacitor. Each capacitor and the respective auxiliary thyristor form a branch and these two branches are each connected in parallel with the main thyristors. A rectifier is connected to keep the capacitors charged in opposing directions.Type: GrantFiled: December 4, 1978Date of Patent: December 9, 1980Assignee: Canadian General Electric Company LimitedInventors: Andrew C. Stevenson, Kenneth R. Fox
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Patent number: 4210858Abstract: A compact and lightweight power supply particularly suited for use as a high voltage supply capable of switching voltage values in short time. The high voltage output is compared against a desired reference value to produce a difference voltage which is integrated. The integrated difference voltage is converted to recurrent pulses having a corresponding width. The pulses are applied alternately to the opposite ends of a centertapped primary winding of a specially wound transformer characterized by a specially wound secondary winding and an air-gapped E-shaped core linking the primary and secondary windings. The secondary voltage is applied to a voltage multiplier circuit to produce the high voltage output of the power supply.Type: GrantFiled: April 19, 1978Date of Patent: July 1, 1980Assignee: International Business Machines CorporationInventors: Leland W. Ford, Alberto M. Ramirez, Gerald L. Smith
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Patent number: 4186434Abstract: A driver circuit is provided for producing and controlling the dead-time of witching transistors in DC-to-DC or DC-to-AC converter circuits to prevent cross conduction and/or to control the output voltage as a function of that dead-time. Driver transistors are switched alternately ON and OFF and drive the switching transistors through a capacitor-shunted transformer primary having a charging current applied to a center tap thereon to predictably control the gradual application to and removal of base drive from the switching transistors, thereby predictably controlling the dead-time of the switching transistors and in some applications, the output voltage of the converter circuit also. The charging current may be either manually or automatically varied to vary the dead-time as desired.Type: GrantFiled: March 23, 1978Date of Patent: January 29, 1980Assignee: The United States of America as represented by the Secretary of the ArmyInventor: Philip M. Cowett, Jr.
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Patent number: 4155113Abstract: Inverter-rectifier combinations of the type which include at least a pair of transistors for alternately applying DC current to a transformer to generate alternating voltage from a DC source, and a digital semiconductor type driving means for alternately providing voltage pulses of given duration and at a periodic repetition rate at each of two outputs for controlling such alternating operation of the transistors is improved in a combination containing a protective circuit located in between the driving circuit and the inputs to the inverter transistors.Type: GrantFiled: October 17, 1977Date of Patent: May 15, 1979Assignee: Litton Systems, Inc.Inventor: David H. Simmons
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Patent number: 4103356Abstract: A synchronization circuit for a free-running push-pull inverter in which the frequency is determined by a saturable transformer in the feedback loop. Synchronization is achieved by momentarily short-circuiting the inputs to the two switching transistors together to initiate the switching cycle.Type: GrantFiled: November 23, 1976Date of Patent: July 25, 1978Assignee: Northern Telecom LimitedInventor: John Reid Finlay
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Patent number: 4074346Abstract: In a high current power supply controlled by thyristors mounted in antiparallel in the primary of the power transformers, saturation of the transformers is prevented by a detection circuit responsive to an unbalance in such bilateral switch and protective action is automatically triggered. Display is provided to identify the defective bilateral switch.Type: GrantFiled: May 13, 1976Date of Patent: February 14, 1978Assignee: Westinghouse Electric CorporationInventor: John A. Riley