Abstract: Improvement for power supplies include a protection circuit having a first L-C filter network, a second L-C filter network and a voltage clamping device such as a zener diode which is disposed between the two L-C filter networks. The protection circuit reduces the magnitude of overvoltage input transients which might otherwise damage the internal components of the inverter. For generating very high output votlages, the power supply includes a high voltage transformer and a Crockoft-Walton voltage multiplier coupled thereto. The high voltage transformer is coupled to an inverter through a coupling circuit which includes a capacitor in one leg of the primary winding and a parallel connected resistor/inductor in the other leg of the primary winding of the high voltage transformer. The high voltage transformer is formed of a multi-sectioned bobbin which is defined around an axially extending core.

Abstract: Two-state, bilateral, single-pole, double-throw, half-bridge power-switching apparatus capable of high speed, high current switching over a duty factor range of zero percent to 100% includes a single-wire connector to a source of switching signals, a first FET whose gate is connected to the single-wire connector, and a second FET having its gate connected to the drain of the first FET and its source connected to the drain of the first FET through a device for preventing, in part, cross-current from the first FET to the second FET and for permitting the gate voltage on the second FET to be raised sufficiently high to turn on the second FET. The apparatus also includes a system for delivering on/off signals to the second FET and for holding the second FET on or off in response to switching signals having a duty factor in the range of zero percent to 100%.

Abstract: 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.

Abstract: In a switching type DC to AC power converter a plurality (A-D, FIG. 6) of pairs of switchers (S1 and S2) are connected through inductors (L.sub.A -L.sub.D) to a load. Each set of switchers is switched to produce a square wave shaped output voltage (FIGS. 5A-5D) at a switch frequency (f.sub.S) and at a modulation percentage to produce an output voltage (E.sub.O) to a load, at a selected frequency. The sets are switched at phased delays, so that the ripple currents through them, when summed up, result in a ripple current I.sub.T at a frequency f.sub.C, where f.sub.C =n.multidot.f.sub.S, n being the number of pairs of switchers. In another aspect of the invention, means are incorporated to prevent the flow of currents between parallel connected amplifiers, characterized by zero output impedances.

Abstract: An inverter is provided, especially for use in an uninterruptible power supply, with its switching transistors being ground referenced and its output voltage fed back and compared to a single reference waveform for a self-setting duty cycle control of the switching transistors. The switching transistors are activated only when the output voltage is outside of a predetermined error band from the desired level, with the control system activating the switching transistors to drive the output voltage to the desired level and deactivating the switching transistors when the output voltage is within the error band. A current limit circuit provides current limit control which varies depending on the angle and magnitude of the output voltage.

Abstract: 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.

Abstract: A laser device equipped with a high-voltage pulse generator wherein the pulse generator supplies an electric energy from a dc power source in an on-off form of a supply voltage to a tank circuit through a transformer, with the switching on and off of the supply voltage being effected in synchronism with the resonance period of the tank circuit. The tank circuit stores the supplied electric energy as a resonance condition so that when the electric energy stored in the tank circuit reaches a predetermined value, a saturable reactor connected between the laser device and the tank circuit becomes saturated and the electric energy in the tank circuit is discharged to the laser device.

Abstract: A PWM inverter including a saturable core and a main circuit comprising a series circuit of a main winding and a resistor in which switching means applies a DC voltage across the main circuit by time ratio control with the polarity inverted alternately, and the on-off control of the switching means is accomplished by using a saturable transformer with a saturable core.

Abstract: An inventive oscillator, inter alia, is disclosed which can be used to generate a frequency modulated control signal or a pulsewidth modulated control signal for application to a switching means in a switching power supply. The output voltage of a power supply is used to control the magnitude of a high bias voltage and a low bias voltage applied to a plus terminal of a voltage comparator, wherein when the output of the voltage comparator is high, the high bias voltage is applied to the plus terminal, and when the output of the voltage comparator is low, the low bias voltage is applied to the plus terminal. A capacitor, coupled to the output of the voltage comparator via a resistor, is coupled between the minus terminal of the voltage comparator and a ground so that when the output of the voltage comparator is high the capacitor charges.

Abstract: A power supply system including a DC-to-AC inverter stage and a voltage step-up transformer is intended to have the output voltage settlement with a minimal delay and suppressed bounce at the start-up of power supply to the load, and also intended to reduce the load voltage bounce caused by the leakage inductance and stray capacitance of a high tension step-up transformer.

Abstract: An inverter arm is made up of two transistors electrically connected in series, each transistor having its own independent control unit. The control units are supplied by a common power supply unit ensuring galvanic insulation by means of a transformer with two distinct secondary windings. This galvanic insulation allows a potential difference of several hundred volts between the transistors and their control circuit.

Abstract: Disclosed is a full-wave output type forward converter wherein a main transformer having a primary winding connected in series with a switching element includes two secondary windings as winding halves divided by a center tap and electromagnetically coupled. A leakage self inductance can be reduced to obtain a high-frequency, high-power arrangement.

Abstract: An EDM machining circuit which is operable at negative polarity and at positive polarity. A push pull circuit is included to provide a symmetrical waveform with either polarity. Switching control of the main switching transistor is provided through a microprocessor.

Abstract: An apparatus for allowing the use of unmatched transistors in a power supply is shown. A potentiometer (482) and a switch (481) divert base drive current away from the transistor having the higher Beta so that the collector currents of the two transistors (477, 484) can be matched. Heat sensitive resistors (480, 483) are thermally connected to the opposing transistor (484, 477) so if the temperature and collector current of one transistor should increase the base drive to the other transistor is automatically increased, thereby causing the collector currents to remain matched. The total collector current provided by the transistors (477, 484) is limited to a safe value by a regulating pulsewidth modulator (457). The use of additional protective diodes (468, 469, 478, 479) prevent transient voltages from affecting the transistors (477, 484) and allow the use of lower power, less expensive transistors.

Abstract: 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.

Abstract: A high-frequency switching power conversion circuit is disclosed. The circuit is capable of operating either as an inverter or as a rectifier, by the use of an array of high-power, bidirectional switches. AC waveforms are produced by ROM-based pulse width modulation, the clocking of which may be phase-locked to an active AC load. Analog voltage sense circuitry detects high or low output voltage and alters the base address in ROM to a lower or higher duty cycle waveform, respectively, providing digital regulation of the output. Overcurrent protection circuitry, responsive to an inductive load, alters the pulse width modulation pattern to produce a dynamically clamped output dependent upon high-power, variable frequency loads. No-load detection circuitry drastically reduces the duty cycle on the switching elements, thus conserving energy when not needed.

Abstract: 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.

Abstract: A method and apparatus for controlling the magnitude of an analog current through a load to be proportional to the magnitude of an input voltage. A sensing resistor is connected in series with the load. A controllable voltage is applied across the series connection of the load and sensing resistor for driving a current therethrough. A pulse width modulator receives the input voltage and a feedback voltage corresponding to the voltage drop across the sensing resistors when current is conducted thereby and produces square wave pulses each having a pulse width which is adjusted in response to a difference between the magnitudes of the input voltage and the feedback voltage.

Abstract: The circuit includes an inverter to be connected to a source of d.c. power. The inverter has a transformer with a center-tapped primary winding. Separate controllable switching devices are connected to the respective ends of the primary winding. Both switching devices are arranged to be connected in common to one output terminal of the d.c. power source. The center tap of the transformer primary winding is arranged for connection to the other output terminal of the d.c. power source. The transformer has a laminated silicon steel core, and includes a secondary winding arranged for connection across the input terminals of a gaseous discharge lamp. A control circuit is connected to control conduction by the separate controllable switching devices in alternating sequence at a desired frequency of operation.

Abstract: A DC-AC converter circuit for a power supply contains a parallel resonant circuit topology. Accordingly, stray capacitance associated with the converter forms a part of the resonant circuit and assists in setting the resonant frequency thereof. The energy in the stray capacitance which is normally lost is recovered by the resonant circuitry. A coupled inductor is connected in series with a primary winding of an output transformer of the converter. The coupled inductor includes a resonating inductor winding and an energy recovery winding which are tightly wound out of phase with one another. Energy from the resonant inductor winding is coupled to the recovery winding when the switching elements of the converter are switched on and off. Therefore, energy otherwise dissipated in switching operation is conserved by being returned to its source. Further, the switching elements of the converter are connected in series through diodes to the return line.

Abstract: 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.

Abstract: 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.

Abstract: A high-voltage converter circuit which uses a slip slide power conditioner to reduce non-monotonic non-linearities in the converter output signal is disclosed. The slip slide power conditioner includes: a choke feed D.C. circulator; two radio frequency (RF) power pumps; a phase detector; a phase controller; and a combiner. The choke feed D.C. circulator receives the D.C. input signal and produces therefrom two voltage output signals which are each sent to one of the two RF power pumps. The two RF power pumps produce two out-of-phase square wave output signals which are algebraically combined in the combiner to form an output signal whose amplitude is a function of phase difference. The phase detector and phase controller sample this output signal and adjust the phase of the two power pumps to remove non-linearities due to secondary ranging (resonance) that beats with harmonics of their square wave signals.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A power converter (10) for supplying an output wave shape as a function of an oscillator (22) input utilizing a power output switching stage. A band limit generator (24) provides two reference signals (HL, LL) which define a band. The two reference signals are compared with a feedback signal from the load, in a detector (26). The detector (26) provides output signals for controlling the switching power output stage (20) to bring the feedback signal within the defined band.

Abstract: An inverter circuit having an output power transformer if provided with a replica driver transformer which is a miniature "clone" of the power transformer. The replica driver transformer uses the same core material as the power transformer and is designed to saturate before the power transformer thereby shutting off the drive to the power switching transistors and saving them from burn out which might otherwise be caused by power transformer saturation. Reset circuits can be included as part of the circuit to assure successful start up preventing first-half-cycle-instant-burnout-syndrome occurrence.

Abstract: An uninterrupted AC supply includes an AC to DC converter having several DC storage devices which maintain a constant DC voltage in the event of a failure of several cycles of the AC source. Each of the storage devices is connected to a separate branch circuit. Each branch circuit includes a transistor that is driven in a linear manner during a portion of a quarter cycle of an AC reference source, so that only one branch conducts current at a time. The DC voltage supplied to each branch and the conducting interval of each branch are such that equal energy dissipation occurs in each branch during each quarter cycle. To enable only one set of branches to be used for opposite polarity variations of the AC reference source, the current from all of the branches flows to a single node, then to opposite terminals of a center tapped transformer primary winding via a pair of switches.

Abstract: A single DC power switching converter feeds two DC load circuits from two transformer secondary windings. One winding is tightly coupled to the primary and its output voltage is controlled using pulse-width modulation. The other secondary winding is loosely coupled to the primary so that its leakage inductance resonates with a secondary capacitor such that its output is controlled by converter frequency adjustment. Thus, both output voltages are controlled using a single power switching stage.

Abstract: 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 elect

Abstract: 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.

Abstract: 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).

Abstract: A power supply for a low-loss sinusoidal drive system is disclosed for powering thin-film electroluminescent displays (TFEL). A DC power source is coupled through a DC-to-AC inverter for driving an LC resonant tank circuit which is used to produce a sinusoidal supply voltage. A sinusoidal supply voltage is then coupled to produce a sinusoidal backplane driving voltage which, in cooperation with a logic circuit, controls the drive for selectively energizing segments of the TFEL display. The power supply is constructed to synchronize itself with the tank circuit in such a manner that sufficient power is added to make up for the tank losses and allow the tank to ring with a sustained constant voltage level. This produces an efficient sinusoidal power source which can accommodate varying loads and is operable at low voltage levels independent of output voltage requirements.

Abstract: A variable voltage power supply including a power source connected to an electrical energy storage means by an electronic switching means. Coupled to the energy storage means is a voltage output circuit providing an output voltage for a load and electrical energy transfer thereto from the energy storage means. A voltage comparator compares the output voltage with a periodically varying reference voltage providing output signals that switch the electronic switching means to cause the output voltage to track the reference voltage.

Abstract: A DC-to-DC conversion circuit for supplying dual positive and negative DC output voltages of the same level in absolute value to a load circuit such as a class B power amplifier. An alternative fluctuation in the positive and negative DC output voltages is regulated, making it unnecessary to regulate both simultaneously.

Abstract: A multiwinding inductor is disclosed which inductor is employed in a power control circuit. The power control circuit is of the type having a transformer which has a center tapped primary winding coupled to and associated with a plurality of secondary windings. The primary winding of the transformer is switched by means of switching devices during a power control operation. The inductor has a first winding in the primary which winding has one terminal coupled to the center tap and a second terminal coupled to a generator and a filter arrangement. Another winding of the inductor designated as a free wheeling winding is in series with an auxiliary impedance and has one terminal coupled to the common terminal of the switching devices and a second terminal coupled through a rectifier to the generator. At least two additional windings of the inductor are coupled to suitable rectifier circuits associated with the secondary windings of the transformer.

Abstract: A switching circuit is employed to control the flow of energy from a power source to a tuned load. The control is achieved by means of a pulse width control voltage. The load current is sensed and fed to a phase locked loop which contains an oscillator producing an output that is slightly above load resonance. The phase locked loop forces the circuit to operate at a frequency where the modulating pulses are initiated at the load current zero crossing. The circuit is shown in use in a regulated d-c power supply and in a fluorescent lamp power supply application.

Abstract: A portable, battery-powered high capacity dc-dc voltage converter suitable for charging capacitor-based devices such as electronic camera flash lamps is disclosed. The voltage converter utilizes two high frequency metal oxide semiconductor field effect power transistors which are driven in a push-pull arrangement by an emitter-follower full wave bridge circuit. The transistors drive a low leakage inductance toroidal ferrite-core power transformer at a frequency which is sufficiently high to avoid saturation of the transformer, resulting in high efficiency and low power consumption. The output of the transformer is rectified to produce a high capacity dc charging signal on the order of 300 volts with a maximum current of 28 amps. The voltage converter is capable of recharging commercially available inexpensive electronic 100-watt flash lamps at a rate of once every 1.8 seconds, compared with a rate of 15 seconds for comparable prior art self-contained charging units.

Abstract: Non-dissipative snubber for a D.C. power switching circuit comprising a main inductance connected in series with a load, a controlled switch, an inductance, and a D.C. voltage source. The snubber includes a branch circuit including a capacitor, a first diode, and an auxiliary inductance in series, mounted in parallel across the switch, with one terminal of the capacitor directly connected to the junction of the switch and the main inductance. The other terminal of the capacitor is connected through a second diode to a point of constant potential having a value about half that withstood by the switch. The snubber permits the use of a capacitor of lower voltage rating than heretofore required.

Abstract: A control circuit for a DC-AC converter which improves the efficiency of the converter and enables it to operate at a higher frequency using the same semiconductor switches. The residual voltage across the conductive switch (9, 10) of the converter is compared with a reference voltage (23) via an analog OR-gate (26) and the control signal for the conductive switch is controlled such that the residual voltage is set to a desired value.

Abstract: A direct current to alternating current inverter with an output transformer is regulated by a pulse width modulator which alternately closes one of two switches connected with the center tapped primary winding of the output transformer. A synchronizing circuit for the pulse width modulator has means for gating synchronizing pulses to the clock of the modulator, blocking synchronizing signals which would cause an unbalance in the duty cycles of the switches and saturation of the output transformer.

Abstract: A push-pull inverter circuit for an inductive load such as a fluorescent lamp. A pair of transistors alternately and repetitively apply energy to the load, and are alternately rendered conductive by stored charges produced by flyback induced voltage in the load, in cooperation with a single mutual control circuit which repetitively renders the push-pull transistors nonconductive and removes their stored charges.

Abstract: 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.

Abstract: A low loss snubber provides stress relief for a first controllable semiconductor switch. The low loss snubber comprises a capacitor in series with a diode. This series combination is connected across the first switch, with the diode poled to conduct current to charge the capacitor when the first switch turns off. The low loss snubber further comprises an energy retrieval converter for removing energy from the capacitor when the first switch turns on. The energy retrieval converter has a second controllable semiconductor switch which is repeatedly turned on and off responsive to the first switch remaining in the closed position. An inductor means is in series with the second switch and the capacitor is provided for transferring the energy stored in the inductor means to an external load when the second switch is open.

Abstract: A sine wave inverter consisting of two substantially constant dc current sources and two transistors to switch the current flow in a load from one branch of the circuit to the other branch, in which the two branches are designed to produce complementary sinsoidal waveforms and thereby provide the load with ac current.

Abstract: An inverter circuit having two pairs of transistors, the transistors of each pair thereof being connected in series to alternately and repetitively apply electrical energy to an inductive load such as a fluorescent lamp. A square wave voltage is applied in opposite phase to electrodes of a first transistor of each pair thereof for rendering them alternately in condition for conduction and nonconduction. Each time a first transistor of one pair thereof becomes nonconductive, current in the inductive load reduces and an inductively induced flyback voltage is generated therein, which voltage is applied to the base electrode of the second transistor of the other pair thereof for creating a stored charge which turns on this transistor and keeps it on during the half-cycle, whereby the pairs of transistors are alternately turned on and off for applying alternating current through the load. Rapid discharge circuits are provided for the removal of residual stored charges.

Abstract: Replacing the timing core of a conventional two-core inverter with a magnetic amplifier allows for control of frequency and for B-H loop symmetry. Switching of the magnetic amplifier results in inverter commutation rather than the familiar pulse width modulation.

Abstract: A system is provided for driving the switching transistors in a push-pull switching mode inverter-type power supply. The system of the invention provides drive current adjusted to the actual power supply load throughout the entire switching cycle from turn-on to the completion of turn-off for each of the switching transistors. There is essentially zero power dissipation in the various elements which make up the system. Moreover, the system obtains substantially all of its drive power from the outputs of the switching transistors themselves, and it provides transformer isolation for the switching transistors.

Abstract: An inverter (34) which provides power to an A. C. machine (28) is controlled by a circuit (36) employing PWM control strategy whereby A. C. power is supplied to the machine at a preselectable frequency and preselectable voltage. This is accomplished by the technique of waveform notching in which the shapes of the notches are varied to determine the average energy content of the overall waveform. Through this arrangement, the operational efficiency of the A. C. machine is optimized. The control circuit includes a microcomputer and memory element which receive various parametric inputs and calculate optimized machine control data signals therefrom. The control data is asynchronously loaded into the inverter through an intermediate buffer (38). A base drive and overlap protection circuit is included to insure that both transistors of a complimentary pair are not conducting at the same time.