Abstract: Two single phase uninterruptible power supplies are coupled together and controlled such that the two-phase output voltage is matched in frequency and phase with the electrical power provided by the electric utility. The phase difference between the electric utility power lines is measured and stored as a reference signal. When electrical power from the electric utility is lost, the stored reference signal is used to control a master and slave UPS to deliver two-phase power having the same frequency and phase.

Abstract: A three-phase voltage stiff convertor (SR) has two six-pulse partial convertors (SR1, SR2). The alternating voltage terminals of the partial convertors are connected to a transformer (TR) with the aid of which the resultant alternating voltage of the converter is formed as the difference between the alternating voltages of the partial convertors. Each partial converter has a separate direct voltage source (C1, C2). The converter has control members (SD) which control the two partial convertors which a mutual phase displacement alternating between +150.degree. and -150.degree..

Abstract: A parallel multi-inverter system including a plurality of inverters connected in parallel to each other through one or more parallel reactors, wherein output voltages of the inverters are controlled on the basis of the polarity of an output voltage command signal and a comparison result between a value obtained by converting the output voltage command signal into a positive one and a carrier signal to reduce harmonic components of the line-to-line voltages, and further two different switching modes to set the output voltage of the system zero are equally used to prevent a circulating current from flowing through the parallel reactors during each zero potential period of the output voltage of the system.

Abstract: A boost convertor power supply comprising an electronic switch controlling current through a boost inductance, a rectifier for charging a capacitor which accumulates the resulting boost charge from the boost inductance, and circuitry for repeatedly switching the electronic switch. A pulse width modulation circuit varies the relative on/off period of each cycle of switching to cause the peck switch current to follow a variable amplitude wave of shape corresponding to the input voltage applied to the boost converter and amplitude controlled by an error amplifier and multiplier thereby regulating the output voltage. A ramp signal generator provides for pulse width stability. An error correction circuit corrects for the difference between average current in the boost inductor and peak switch current to modify the pulse width modulation circuit to reduce distortion of the line current waveform.

Abstract: A method for reducing the signal harmonics of the output fundamental signals of a three-phase inverter systems made up of an N number of inverter bridges achieves harmonic signal reduction by combining the outputs of immediately adjacent bridges separated by 60.degree./N relative to one another and then summing the combined sum signal with the outputs of the next immediately adjacent bridge.

Abstract: The ripple factor in an electrical power supply of a dc-dc voltage raising type is reduced by using two double alternation dc/ac converters driven in phase quadrature with respect to each other. The signals delivered by the dc/ac converters are then combined by two transformers, the secondary coils of which are series connected. It is shown that the ripple factor is reduced and, similarly, that the reactive energy due to the commutation of th dc/ac converters is reduced even if it so happens that the power transmitted is doubled.

Abstract: A novel electrical inverter includes a source of direct current (DC) signals, a plurality, N, of addressable electrical switching devices where N does not equal two configured in parallel to receive signals from the DC source. The electrical switching devices generate a plurality of output signals phased relative to one another. An output transformer has a plurality of parallel configured input inverter winding sets for receiving and transforming a respective one of the phased electrical switching device output signals, and a plurality of serially configured output winding sets providing three phased fundamental signals as the sum of the transformed signals.

Abstract: A power converter device including a plurality of self-commutated voltage type converter each connected to a common d.c. circuit, a plurality of transformers each having d.c. windings and a.c. windings, each of the d.c. windings being connected to an a.c. output terminal of a respective one of the converters and each of the a.c. windings being connected in series, an a.c. switch through which the serially connected a.c. windings of the transformers are adapted to be connected to a utility power system, and a d.c. overvoltage suppression device, installed in the common d.c. circuit, wherein the transformers are connected to the utility power system by synchronous making, and the d.c. overvoltage suppression device is connected to the common d.c. circuit when the converters are stopped temporarily.

Abstract: A power converter device including a plurality of self-commutated voltage type converters each connected to a common dc circuit, a plurality of transformers each having dc windings and ac windings, each of the dc windings being connected to an ac output terminal of a respective one of the converters and each of the ac windings connected in series, an ac switch through which the serially connected ac windings of the transformers are connected to utility power systems, a capacitor provided in the common dc circuit, a dc overvoltage suppression means installed in the common dc circuit, and a current limiting device, wherein the capacitor in the common dc circuit is charged through the current limiting device means before starting the self-commutated voltage type converters, and the dc overvoltage suppression means is then connected to the common dc circuit and removed after the self-commutated voltage type converters are started.

Abstract: A power system includes as many synchronizing units as the number of the power units. Each synchronizing unit has been designed to receive an activation signal at its input and to be connected to the other units through of a first and a second discs. Each synchronizing unit delivers to its output a synchronizing clock signal for the respective power units. The first synchronizing unit which receives the activation signal is qualified as the master unit. This master unit applies a predetermined polarity to the first bus and a clock signal to the second bus in order to synchronize the other units in response to the detection of the polarity on the first bus, the other units are characterized as slave unit.

Abstract: A quasi-harmonic neutralized static power converter comprises one or more threephase phase shifting transformers having open primary windings fed at opposite ends by poles in separate ones of an associated pair of six-pulse bridge inverter circuits. The secondary winding of at least one of the phase shifting transformers is a delta winding or a wye winding connected to a neutral line. In order to block zero sequence currents which would be induced in such secondaries, a zero sequence blocking transformer is inserted in either the primary of secondary of any one of the phase shifting transformers. Preferably, the zero sequence blocking transformer has three identical zero sequence blocking windings wound on a common core. Each of the zero sequence windings is connected in series with a separate one of the windings in the selected transformer primary or secondary.

Abstract: A polyphase inverter includes a plurality of unit inverters connected to a single power source to form an a.c. output with the unit inverters being polyphase, thus to take out the resultant output. In this polyphase inverter, a series circuit including a capacitor and a fuse, and a reactor for protection coordination of the fuse are connected between the d.c. power source and each unit inverter. The resonance frequency of a resonance circuit constituted by the capacitor and the reactor is selected so that it is substantially equal to the product of the number of unit inverters, the number of pulses of the unit inverter, and the output fundamental frequency.

Abstract: The invention relates to a circuit arrangement for adjusting a high voltage. According to the invention, several semiconductor adjustment members are connected in series, only one of the adjustment members being directly coupled to a control signal source, while the control voltage for the remaining adjustment members is each time derived from the output voltage of the preceding adjustment member.

Abstract: Each power supply of a number of power supplies equally shares the current load supplied by the respective parallel voltage outputs of the supplies. Each power supply is identical to the others and each has the capability to operate as a stand-alone power supply, a master of a master/slave combination, or a slave of a master/slave combination. The determining factor of whether a unit is a master or a slave of a master/slave(s) combination is a single two conductor cable which has the master connection at one end and the slave connector(s) at the remaining end(s). Whichever of the otherwise identical units that the master connection is connected to will be the master unit and whichever of the units are connected to the slave connection(s) will be the slave unit(s). Thus a simple, inexpensive, interchangeable master or slave capability is provided with units which are controlled by the master to equally share the current load.

Abstract: A pair of quantized duty ratio proportional-integral-differential (PID) converters are coupled to provide power sharing to a load. One of the converters is a master and the other is a slave, and a PID controller is coupled to both of the converters. The PID controller also supplies two digital offset signals to the converters during normal operation, which insures load sharing by control of the duty ratio of the converters. If one of the converters fails, a sensor control unit switches control to the other unit and the digital offset signal goes to zero.

Abstract: Apparatus for synchronizing the oscillators of several clocked direct voltage converters where each direct voltage converter has a control circuit with the oscillator as an integrated component and each control circuit has a connection for a capacitor and a connection for a resistor for defining the oscillator frequency. Commercial elements TDA 4714 and TDA 4716 are preferred as the control circuit. The synchronization is attained by adjusting the frequency of the oscillator of a first direct voltage converter to be higher than the frequency of the oscillators of the remaining direct voltage converters. A pulse sequence with an impulse frequency proportional to the oscillator frequency of the first direct voltage converter is transmitted by the first direct voltage converter to all of the other converters through an element that provides isolation between the different potentials. The pulses of the pulse sequence adjust a predetermined charging state for the capacitors of the other direct voltage converters.

Abstract: A programmable slewing power supply is used to drive microwave phase shifters according to a command signal from a system controller using: a Milberger converter; a power source; a rectifying circuit; two differential amplifier circuits; and two comparator amplifier circuits. The Milberger converter outputs a combined square wave which it produces by combining two independent square waves which add or cancel. The power source receives the combined square wave and outputs: a reference voltage, a positive voltage signal; and a negative voltage signal. The rectifying circuit produces a rectified command signal by rectifying the command signal from the system controller. The two differential amplifier circuits respectively measure the positive and negative voltage signals with respect to the reference voltage to produce a measured positive voltage signal, and a measured negative voltage signal.

Abstract: A DC-DC converter converts an incoming unstabilized D.C. voltage to three stabilized output D.C. voltages. The converter contains two chopper stages (1, 2) with associated transformers, rectifiers (3, 4, 17a, 17b) and smoothing filters (5, 6, 18). The two chopper stages give a first and a second pulse-formed output voltage (U.sub.a and U.sub.b) which are regulated by shifting the leading edge of the pulses in the first output voltage (U.sub.a), while the second output voltage (U.sub.b) is regulated by shifting the trailing edge of the pulses. Two output voltages (U.sub.1, U.sub.2) are obtained after recitfying and smoothing. The third output voltage is obtained by connecting in parallel the outputs of two full-wave rectifiers (17a, 17b) which are magnetically coupled to the outputs of the two chopper steps, and by connecting a smoothing filter (18) to the common output of both full wave rectifiers. Regulation of the third output voltage (U.sub.

Abstract: A power converter typically used for operating electrical machines and provided with protective measures to protect against overvoltages which can otherwise occur in the process of switching off the inductive loads represented by the electrical machines. To that end, the converter includes plural bridge circuits having a.c. voltage terminals and d.c. voltage terminals, wherein the a.c. voltage terminals are phasewise parallel-connected and coupled to each other via at least one capacitor and wherein the d.c. voltage terminals are coupled to each other via at least one intermediate circuit reactor. The bridge circuits include bridge arms having GTO thyristors that can be switched off, and the plural bridges are driven out of phase with respect to one another. In this way, the converter supplies an alternating current which is relatively near-sinusoidal and exhibits a low harmonics content to the electrical machine.

Abstract: A power supply system is disclosed in which each of the phases of a three phase AC source are rectified and inverted. During inversion high frequency signals are obtained corresponding to the phases of the AC source which are synchronized so that their zero cross points occur at the same time. The high frequency signals are superposed in series to produce an output signal for a load which has a constant power and diminished current distortion.

Abstract: A pulse width modulated D. C. to A. C. inverter circuit includes a first set of MOSFETS operated at a line frequency for transmitting high frequency clock pulses to a second set of MOSFETS for outputting a D. C. signal derived from a D. C. source. The inverter is part of an uninterruptable power supply and is operated upon the failure of the line A. C. to supply A. C. signals to a load. The high frequency clock signals are modulated on the A. C. output of the inverter. Two separate and distinct power switching channels are provided with each channel supplying one half of the sine wave outputted by the inverter.

Abstract: A twelve-pulse control current inverter system having two six-pulse powered channels connected to a source of variable dc current is selectively operable to control either a three-phase motor or a double three-phase motor. Signals representing the phase currents of each of the two channels are combined with direct and quadrature motor flux signals, the latter signals being shifted in phase in the case of the double three-phase motor, to produce torque signals representing the motor torque produced by each of the two powered channels. These two torque signals are then combined to provide a total torque signal which, in turn, is utilized in the development of an angle signal for the control of the two current inverters.

Abstract: An audio signal tracking power converter has a master converter and a slave inverter which are connected in parallel to a dc power source that is to be converted and provide a first and second ac output signal. The first ac signal and the second ac signal are combined and converted to a dc signal that tracks the input audio signal. The master inverter is controlled by a free-running pulse generator which pulse-width modulates the first portion of the dc power that is converted to the first ac signal. The slave inverter is pulse-width modulated by pulses that result from the comparison of the audio signal that is to be tracked and a reference signal generated from the pulses from the free-running pulse generator.

Abstract: This invention relates to a pulse width modulated inverter circuit having an output signal with reduced harmonic content. The inverter circuit includes a first circuit that provides a filtered fundamental pulse width modulated signal. A second circuit is electrically coupled to the first circuit to receive the signal and sum therewith a controlled signal and the filtered fundamental pulse width modulated signal. The second circuit thereby providing the output signal with reduced harmonic content.

Abstract: A high current, low voltage, regulated D.C. power supply incorporating a parallel pair of bridges connected across a D.C. supply and each having alternately switched opposite legs for producing across its output a relatively high frequency A.C. to a stepdown transformer. Each of the bridges is switched out of phase with the other to minimize output ripple in the combined D.C. produced from rectifiers at the secondary of the stepdown transformers. Regulation of the supply is provided by a current sensor at the secondary of each transformer which produces a signal that is compared with a signal representing D.C. output level to alter the duty cycle in the switching circuitry to the parallel bridges. The novel feature is that the regulation control circuits of two or more identical supplies may be coupled to produce master-slave power supply combinations capable of greatly increasing the output power capabilities.

Abstract: An inverter connection has an inverter bridge which, in series with a controllable valve, is connected between terminals for connection to a direct voltage source. A turn-off circuit is arranged for simultaneous turn off of the thyristors of the inverter. The turn-off circuit comprises a capacitor connection and a thyristor connection which is controllable in both directions. The latter is connected, in series with at least one capacitor, between a point which is located between the valve and the bridge, and at least one of the terminals. An inductor is arranged in at least two of the three current paths between said point and the terminals.

Abstract: A pulse width modulation (PWM) converter circuit for transforming a first DC voltage into a secondvoltage (AC or DC), wherein the magnitude of the second voltage is regulated by the converter circuit. The converter circuit comprises a clock circuit, a master pulse width modulator (PWM) circuit and n slave pulse width modulator (PWM) circuits. The clock circuit provides a symmetrical train of rectangular pulses on each of n+1 conductors, wherein only one pulse occurs on any one of the conductors at one time. The master PWM means is responsive both to the train of pulses on one of the n+1 conductors and to a feedback signal indicative of the magnitude of the second voltage; the master PWM means controls the flow of current, due to the first DC voltage, through a portion of a transformer primary winding.

Abstract: An inverter arrangement comprising two controlled three-phase inverters is disclosed. The inputs of these inverters are preferably connected to a common DC voltage source, while the output voltages delivered by the inverters are of rectangular waveshape and are added together by means of transformers to form resultant output voltages. In accord with the invention, in order to obtain resultant output voltages whose harmonics are of orders which do not change when voltage control is applied, all the output inverter voltages are caused to comprise in each period a positive and a negative voltage pulse, each of which pulses has breaks or no-voltage intervals of controllable width positioned at predefined places within the pulse.

Abstract: An inverter circuit which provides a synthesized sinusoidal output waveform having a low harmonic content. The inverter is light in weight, highly efficient and driven by a fundamental rectangular component having a frequency equal to the desired synthesized sinusoidal output frequency. Single-phase or three-phase output is provided.

Abstract: An inverter for producing regulated AC voltage from an unregulated DC voltage source, such as a battery, employs two stepped voltage waveform generating means independently controlled in phase to produce waveform outputs that approach sine waves which are additively combined to produce an AC output voltage whose amplitude is sensed to produce a feedback signal for comparison with a reference voltage to produce an error signal that causes one stepped waveform generating means to so shift in phase relative to the other as to reduce the error. Each stepped voltage waveform generating means is capable of producing at least half the total desired AC output voltage, so that the DC voltage source may drop by as much as 50% and the desired AC output voltage can still be maintained by shifting the relative phase between the stepped waveforms.

Abstract: An electrical power converter comprising two current-fed square wave chops the outputs of which are combined and rectified to yield a variable and regulated output voltage. The phase relationship of the choppers are varied to achieve output voltage control and regulation. The chopper outputs are combined in such a way that the choppers never experience the open-circuit inductance of their output transformers. This enhances frequency agility. A novel choke feed system is provided in which the choke flyback energy is absorbed and then transferred to the input of the other chopper.