Abstract: A sinusoidal synthesizer is shown which produces a sinusoidal AC power output from a modulated pulse train. The pulse train is modulated by two independent feedback loops which each use the sinusoidal output as its reference. The first loop controls output voltage by a high gain negative feedback signal to a pulse width modulator, while the second loop shapes the sinusoidal output by a less than unity gain, positive feedback signal to a second pulse width modulator.

Abstract: A power transformer of an inverter power supply has a primary winding coupled to a source of DC voltage. First and second transistor switches are coupled to the primary winding in a push-pull arrangement. A drive winding of a saturable transformer is coupled to the base electrode of each of the two transistor switches to alternately apply forward drive to each switch. A control winding of the saturable transformer is supplied with a control current that reaches a magnitude that magnetically saturates the core of the saturable transformer to remove forward drive from the conducting transistor switch for developing an alternating polarity output voltage across a supply winding of the power transformer. A capacitor and an inductor form a resonant circuit upon attainment of core saturation.

Abstract: A voltage snubber connected to the output terminals of a transistorized, push-pull inverter for supplying bidirectional current to an inductive load comprises a snubber capacitor and relatively large valued resistor connected in series with each other across the output terminals of the inverter and a switching circuit for bypassing the resistor during turn-off periods of the inverter transistors. The value of the snubber resistor is high enough to provide slow recharging of the snubber capacitor during turn-on periods of the inverter transistors to reduce transistor power dissipation. When the resistor is bypassed by the switching circuit during the inverter transistor turn-off periods, the snubber is gated on to suppress high voltage surges generated by the inductive load. The snubber switching circuit is responsive to current sensors or logic commands connected in circuit with the inverter to detect turn-off transistors of the inverter transistors.

Abstract: The invention relates to static converters of the symmetrical type whose function is to convert an input direct current voltage into an output alternating current voltage of chosen frequency and power. The self-oscillator according to the invention is composed of two transistors mounted with a common emitter. The device is energized, for instance, from a main power supply unit, associated with a voltage limiter circuit, which subjects the output power of the device to any parameter. The capacitive power factor of the device is compensated by an inductance connected in series with the main power supply. The device according to the invention can replace, advantageously, the conventional "ballast" for fluorescent lamps.

Abstract: A control circuit for an inverter includes a DC voltage source having first and second terminals, an input transformer having a primary winding, a pair of secondary windings and a magnetic core, an output transformer having a primary winding, a secondary winding and a feedback winding, first and second transistors each having a control electrode, the main current paths of which are connected, through the primary winding of the output transformer, between the first and second terminals of the DC voltage source and the control electrodes of which are connected to the pair of secondary windings of the input transformer, coupling circuit for connecting the primary winding of the input transformer to the feedback winding of the output transformer, a starting circuit for putting one of the first and second transistors in its conductive state when the DC voltage source is operated, and a control circuit including at least a shorting winding provided in connection with the magnetic core of the input transformer so as

Abstract: A D.C. to D.C. converter is disclosed which includes a first and a fourth, and a second and a third, sequentially operating transistors. The D.C. to D.C. converter further includes a saturable transformer having a center-tap and resistive networks interposed among the four transistors. The D.C. to D.C. converter is adapted for energization by an input D.C. voltage. The transistors of the D.C. to D.C. converter cause one side of the input D.C. voltage to be sequentially applied to opposite sides of a primary winding of the transformer which, in turn, cause the transformer to be sequentially excited into positive and then negative saturation conditions. The sequential excitation of transformer develops a time varying square-wave type signal at the secondary windings of the transformer which is further converted into a D.C. signal by an A.C. to D.C. converter.

Abstract: A power inverter oscillator circuit has an output transformer with a primary winding, coupled in parallel with a capacitor, and the opposite ends of which are connected to the respective emitters of a PNP and a NPN transistors. The collector of the NPN transistor is coupled to the positive terminal and the collector of the PNP transistor is coupled to a negative terminal. In addition, a switching transformer is provided having a primary coil coupled at one end to one terminal and at the other end to the emitter of the transistor which is coupled to the other terminal. The switching transformer has two secondary coils or windings wherein one of the secondary coils is coupled between one terminal and the base of the transistor whose collector is coupled to the other terminal and the other secondary coil is coupled between the base of the other transistor and the remaining terminal.

Abstract: A D.C. to D.C. voltage converter is disclosed that operates with various applied D.C. input voltages, each having a different voltage level, to develop a desired D.C. output voltage. The D.C. to D.C. voltage converter has a saturable transformer that is sequentially excited into its positive and negative saturation conditions under control of sequentially operating first and second transistor diode combinations. The D.C. to D.C. converter has a base drive current circuit comprised of a full-wave rectifier and a multiple level current limiting circuit. The base drive current circuit is interposed between a base drive winding of the saturable transformer and the base electrodes of the transistors of first and second transistor diode combinations. The base drive circuit adapts the saturation condition of the first and second transistor diode combinations to the level of the applied D.C.

Abstract: A novel and economical transformer is described for use in a static inverter in association with one or two switching devices, typically transistors. The transformer produces an output for control of the associated switching device(s) which changes in sense as a function of the flux level in the transformer core. The arrangement is applicable to a figure "8" flux configuration such as is achieved from two "E" cores, and requires only a single aperture located at the base of the common branch. Control is effected by a single primary and single secondary winding wound through the aperture. With two switching devices, two apertures are normally provided. The core which supports a figure "8" flux configuration may take other more economical alternatives such as "I" core, "T" core or a single "E" core.

Abstract: An improved high efficiency push-pull inverter circuit employing a pair of switching transistors that are alternately triggered into conduction by a control circuit, for converting DC voltage into high frequency AC voltage. The control circuit includes a pair of saturable transformers that are non-coupled to each other and are each connected to the base of a respective transistor. The bases are isolated from ground potential by a capacitor, and significant reverse voltage signals are developed and alternately applied to the base of a conducting transistor for rapidly turning it off, thereby increasing device switching speed and overall efficiency of the circuit.

Abstract: A battery package having a casing which contains at least one electrochemical cell electrically connected to a DC to DC converter. A pair of electrical connections are located on the casing to electrically connect the battery package to a load. The converter conducts and the cell discharges only when a load is present across the electrical connection.

Abstract: This high frequency voltage generator which may be used particularly in surgery for supplying an electric bistoury, comprises a power oscillator operating an output transformer. A chopping supply is placed in the direct control chain of the power oscillator. The output voltage of the generator is controlled by a first regulation loop whose reference value is increased by means of a positive feedback proportional to the output current.

Abstract: A self-oscillating, push-pull inverter circuit is described wherein positive feedback signals are provided alternately to the bases of a pair of switching transistors by a single miniature saturable current transformer. The circuit performance relies on a pair of diodes having special characteristics connected across the base-emitter junctions of the respective switching transistors.

Abstract: A power source provides continuous AC power by employing a bi-directional converter which interfaces a rechargable DC power storage device with AC mains power and AC loads. The bi-directional converter includes a transformer having first and second windings coupled in reverse polarity through dual switching means in parallel with one another. The switching means are coupled to a state controller responsive to conditions at the AC mains terminal, the AC load terminal and the DC power terminal. There are two general operating conditions, an active condition wherein DC power is provided to the AC load, and a standby condition wherein power is recovered by the DC storage device. In the standby condition, the converter operates in a so-called "flyback" mode to recover power and to direct it to the DC storage device. In the active condition, the converter is pulse-width modulated according to a predetermined duty cycle to produce an AC sine wave output at the AC load terminals.

Abstract: An electronic ballast-inverter for multiple fluorescent lamps employs a push-pull inverter and a series resonant circuit for driving the lamps. The inverter operates at the resonant frequency of the series resonant circuit. Current in the resonant circuit is limited, for low-load conditions, in response to a sensing voltage which is used to lower the frequency of operation of the inverter, to make the load more reactive.

Abstract: A DC to AC power inverter for transforming a DC voltage to an AC voltage, and supplying the AC voltage through a transformer to a load, wherein the transformer is provided with a number of taps to permit connection of a capacitor through switch means to a selected tap thereby to improve matching the load impedance with the inverter to improve efficiency by virtue of improving power factor.

Abstract: The current from an external AC power source is rectified to charge a DC battery and conduct current therethrough in series with a load during one-half of each power cycle of the external source. During the other half of each cycle, current is conducted through the load by discharge of the battery through a transistor that is switched to its conductive state by a phase control transformer connected to the power source.

Abstract: A free-running inverter preventing excessive current spikes comprises a transformer and a switch means for alternately connecting, and then disconnecting, a DC voltage to a transformer primary winding which encloses a parallel combination of a saturating magnetic core and a non-saturating magnetic core. A transformer feedback winding enclosing only the saturating core drives the switch means during and between switch states. Switching between states is accomplished prior to saturation of the composite core.

Abstract: A converter power supply apparatus includes a direct current power supply and an oscillator circuit comprising a feedback transformer and two semiconductor switching devices arranged to be turned on alternately to produce alternating currents in primary winding means of the feedback transformer and in a load circuit. Circuit means couple the load circuit to secondary winding means of the feedback transformer so as to augment control currents fed to the switching devices. Circuit means may be provided to generate a starting pulse and to feed this pulse to the oscillator circuit to cause oscillation to recommence after disconnection of the load circuit. The direct-current source may be provided by rectification of an A.C. input and this input may be controlled in accordance with output voltage of the converter to stabilize the output voltage.

Abstract: A power system provides a duty cycle modulated high frequency carrier signal to an inductive load with positive and negative buses. During the inductive energy discharge period the energy stored in the inductive load causes a reversal in the polarity of the inductor terminal and tends to drive the new polarity towards infinity. Thus, the magnitude of one of the buses may be increased as the result of duty cycle modulation. First and second inverters are coupled in parallel across the positive and negative buses. First and second series coupled capacitors are also connected in parallel with the inverters. The power inverter senses the increased voltage on the second bus as a result of the inductive energy discharge and transfers that energy back to the first bus. Power may thus be sensed, converted in form, and transferred from one bus to another while conserving 90% of the energy which would otherwise be wasted.

Abstract: This invention provides an inverter circuit in which an output transformer has a tapped primary winding, one portion of which provides a collector load for a first transistor and the other portion of which provides a collector load for a second transistor, with a saturating transformer arranged to provide oscillatory positive feedback from the collectors to the bases of the transistors. The feedback paths from the saturating transformer to the bases of the transistors each includes the base/emitter path of a respective additional transistor and current is supplied to the collectors of the additional transistors in order to maintain operation during saturation.

Abstract: A circuit for the production of an output voltage generated based upon an input direct voltage and a given desired voltage. A series connection comprises a longitudinal regulating member, an inductor and a push-pull current transformer which produces the output voltage. The input direct voltage is fed to the push-pull current transformer. The push-pull current transformer includes a push-pull transformer having push-pull primary winding and a secondary winding. In addition, the push-pull current transformer includes switching transistors which are switched on and off in push-pull by a control circuit. The control circuit delivers a suitable cyclical changing control signal to the switching transistors. Circuitry is provided for minimizing if not eliminating spikes in the current occurring during a switching of the switching transistors. As a result, the switching transistors remain free from excessive voltages which can damage same.

Abstract: A high frequency transistor ballast is utilized to drive flourescent lamps. The electrical system of the ballast consists of a central rectifying and control panel and a high frequency inverter. There is also provided a low energy switch in the high frequency inverter system controlling the operation of the high frequency transistor ballast.

Abstract: An electrical inverter circuit for converting d.c. electrical input into an a.c. electrical output involving the control of active switch elements in the primary of an output transformer circuit by, in part, providing a further controllable active element in circuit with the active element switches such that the primary winding current also flows therethrough. Synchronous control means are provided for synchronously controlling this further active element so as to increase its electrical impedance during at least a portion of each switching transition of the active element switch means so as to further aid and promote the rapid and efficient transitioning of the active element switches. Various alternative circuits are shown for this and for detecting the switch point as a function of primary transformer winding current and for further controlling the transition of the active switches in combination with the increased electrical impedance of the further controllable active element in circuit therewith.