Abstract: A magnetic filter filters substantially all of the harmonic frequency currents from a plural-phase power circuit. The power circuit may have three power lines which conduct three currents in a first current set and three power lines which conduct three currents in a second current set. The second current set is displaced from the first current set by a predetermined phase shift. The current sets have a fundamental frequency and a plurality of harmonic frequencies of the fundamental frequency. The magnetic filter may include two transformers each of which has three windings. A first transformer may receive two currents from the first current set and one current from the second current set. A second transformer may receive one current from the first current set and two currents from the second current set. The magnetic filter may also include a phase-shifting coupling transformer having six input phases for receiving the six currents.

Abstract: A high-power power supply produces a controllable, constant high voltage put under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules.

Abstract: In a delta-connected power supply system, phase switching circuits are employed and are activated during the failure of one of N+1 converter units. This activation is employed even though there has been no outage in any one of the input phases. The result is two operating converters running in effect as three-phase converters. Since each of the converters then acts as a full wave three-phase bridge with a resistor load, the line currents are perfectly balanced although unity power factor is not maintained during this non-normal mode of operation. In such circumstances, higher power factor is temporarily sacrificed to achieve continuous operation and therefore higher overall system reliability.

Abstract: An uninterruptable power supply incorporates a plurality of substantially identical inverter modules in combination with a plurality of transformers. Each of the inverter modules is coupled to one coil of a respective transformer. The second coil of the transformers are electrically coupled in series. The inverter modules can be driven by a battery and the switched outputs therefrom, transformer coupled, can be added in the series connected second windings thereby producing alternating output voltages and currents of any desired magnitude. Other output voltage waveshapes are also possible.

Abstract: A boost converter having a plurality of boost converter units in parallel operation. Within each boost converter unit, current transformers 22,23 are connected in series respectively to switching element 7 and diode 8. The current transformers 22,23 permit detected current therefrom to output current detection signals from current detection circuits. Then, the current detection signals within one converter unit 3 will be compared with those within the other converter unit 3A in parallel operation by comparing circuit 33. On the basis of a result of such comparison, D.C. output voltage Vout can be controlled to be equal to each other in each converter unit 3,3A.

Abstract: An improved temperature control system for a power conversion circuit having two or more power converters operating in parallel and providing output power to a single load. The temperature control system maintains the temperature of each of these power converters at approximately the average temperature of the power converters. A detector coupled to each power converter detects the temperature of the power converter and generates a measurement signal that is a function thereof. A reference signal is generated that is a function of each measurement signal. A control circuit responsive to the measurement signal of each power converter adjusts the output power of that respective converter as a function of the difference between that converter's measurement signal and the reference signal such that the temperature of each power converter approximates the average of temperature of the power converters.

Abstract: In a uninterruptible power supply in which a plurality of inverters are operated in parallel, a current control loop is provided which responds to the magnitude of an output current of each inverter brought into parallel running to change a command value for a voltage waveform control circuit associated with each inverter, and the gain of the current control loop is made to be variable, whereby currents shared by the inverters can be set desirably to effectively suppress a cross current flowing between the inverters upon establishment of parallel running.

Abstract: A parallel operation controller for power converters which performs parallel operation control of a plurality of power converters having input terminals connected to a DC voltage source and output terminals connected to each other through reactors. The parallel operation controller includes: three-arm modulation control signal generating devices for generating three-arm modulation control signals each serving as a voltage command value for each phase of corresponding power converters; a voltage fixing period determining circuit which selects, on the basis of a three-arm modulation control signal from one of the three-arm modulation control signal generating devices, a phase fixing the voltage level thereof to a predetermined DC voltage level, and determines a period in which the voltage level is fixed. This parallel operation controller reduces the amount of circulating currents which flow between phases of unit inverters.

Abstract: A UPS device adapted for parallel connection to a load along with one or more other UPS devices, having circuitry for sharing of the load, including load harmonics. A feedback network has an error signal circuit which generates an error signal representative of the difference between the actual current provided by the device and the designated share of current it should provide. The error signal is transformed by a value representative of the effective output impedance of the UPS inverter, whereby the inverter is controlled to share the fundamental of the load current as well as the harmonics.

Abstract: An improved current sharing signal coupling/decoupling circuit for power converter systems, including the provision of an individual current sharing signal coupling/decoupling circuit for each module of a number of parallel connected modules, each circuit providing an interface between a module's "current sharing signal" port and a common connection bus. The signal coupling/decoupling circuits also share a common ground noted in the disclosure as "current sharing signal ground". The signal coupling/decoupling circuit includes a comparator, a bi-directional switch and a variable voltage reference. The comparator senses the difference between the voltage on the common connection bus, the "common current sharing signal," less an amount set by the variable voltage reference circuit, and the voltage on the module current sharing signal port, the "module current sharing signal".

Abstract: A system for sharing of switching losses of parallel transistors is disclosed. The system includes a plurality of switching transistors connected in parallel for providing a current to a load. A pulse generator provides pulse width modulated pulse cycles in response to the load current each pulse cycle having a pulse signal. An alternate selector is responsive to said pulse cycles, and provides the pulse cycles to the transistors, such that for each pulse cycle a predetermined transistor turns ON substantially prior to the other transistors, dissipating substantially all the turn ON losses, and a predetermined transistor turns OFF substantially later than other transistors, dissipating substantially all the turn OFF losses.

Abstract: A receiver circuit relies on four novel pulse width timer/integrators to filter input data signals having a frequency less than a preselected maximum and greater than a preselected minimum. The circuit also rejects a single sine wave cycle. If an input pulse greater than a preselected maximum pulse width is encountered during data reception, then reception activity is terminated. A preferred embodiment of the receiver circuit implements IEEE 802.3 10 Base-T Ethernet receiver requirements utilizing a unique pulse width timer design.

Abstract: The synchronous switching power supply can be employed in power supply systems requiring multiple outputs and extremely high efficiency. No minimum load is necessary. A switching power supply with boost and/or flyback converters comprises a switching circuit for providing an AC signal. Two diodes rectify the AC signal and provide a pulsating DC signal to a node. An inductor is coupled thereto for attaining a current. A capacitor is coupled to the inductor for providing a first DC output signal which is also fed back to the switching circuit. The boost and flyback converters are coupled to the node for converting the pulsating DC signal into a second and third DC output signals.

Abstract: An electric power system having power supplies connected in parallel to a common bus includes a voltage feedback and current feedback loop for each supply. A voltage feedback signal and a current feedback signal are combined with a reference signal to produce an error signal. The output voltage of each supply is controlled in response to its corresponding error signal, to achieve current sharing and redundancy without interconnections among the control circuits of the various supplies.

Abstract: A parallel operation power supply control system has a plurality of switching power supply modules for supplying electric power in parallel to a logic device, and a parallel operation power supply control module connected to a superior controller for control of the plurality of the switching power supply modules. Each of the plurality of the switching power supply modules comprises a DC-DC converter, a drive pulse generator for driving the DC-DC converter, and an electric current feedback unit for detecting an electric current outputted from the DC-DC converter and for feeding the detected result in the form of a first data to the parallel operation power supply control module.

Abstract: A single transformer converter which may switchably disconnect all of its converter outputs, or alternatively just some of the converter outputs. In some electronic systems this would allow the turning-off of some units, such as printers, while leaving on other units, such as a CPU or a twenty-four hour clock. Further, an uninterruptible output is provided by the converter to maintain applications and operating systems software stored a CMOS RAM even in the event of a power outage.

Abstract: Prior voltage balancers for three-phase inverters are useful only with inverters which are not in wide use today. In order to overcome this problem, a voltage balancing circuit for a commonly used inverter balances N phase voltages produced on N output lines. The circuit includes switch controllers coupled to the N output lines for sensing the magnitude of each phase voltage and N-1 voltage combining circuits responsive to the switch controllers and coupled to N-1 output lines for modifying the voltage magnitudes on the N-1 output lines whereby the N phase voltages are maintained within a range of voltage magnitudes.

Abstract: Current sharing between paralleled power converters is attained by adjusting the error signal in the converters regulation circuit to assure that all the paralleled converters have a regulated output voltage that forces the converters to share the load equally. In particular circuitry is provided to limit the variation in output voltage that can be achieved through operation of the current sharing control.

Abstract: A coupling system in which power converters are coupled through a DC circuit to exchange active power between the converters comprises a control apparatus for controlling active power exchanged between each converter and its AC system. The control apparatus includes an automatic active power regulator for regulating active power exchanged between the converters and the AC system to be equal to be predetermined active power reference value, and an automatic DC voltage regulator for regulating a DC voltage of the DC circuit to be equal to a predetermined DC voltage reference value. When an output signal from the automatic active power requlator of each converter is input as an upper limit value of an output signal from the automatic DC voltage regulator, a DC voltage reference value of one converter is set to be equal to or larger than a DC voltage reference value of the remaining power converter.

Abstract: A parallel operating system for A.C. output converters of high frequency PWM inverters of an instantaneous current valve control type is provided with a current minor loop for controlling the instantaneous value of the output current. The current of each inverter minor loop is adapted to be supplied with a command value from a voltage major loop and a command value corresponding to the load current to be borne by each converter derived from the load current, as the command value for the current to be output by the converter for maintaining the output voltage at a sine wave.

Abstract: An error amplifier is disclosed for use in linear or switched-mode voltage or current regulators that use a transconductance type power-amplifier, enabling easy modular parallel connection of said regulators by simply parallel wiring of normally externally accessible nodes of the individual regulators: power-input, power-output, error amplifier output, and error amplifier input, to boost the system's total output power by about equally sharing the total output power among the individual regulators, includinga. an amplifier with grossly asymmetric output current capability in sink and source directions; andb. a sense circuit to slightly modify the voltage on the reference input of the said amplifier when the lower value output current limit becomes active so that it causes positive feedback thereby ensuring that at any time only one of the plurality of parallel operated amplifiers is active and controls the system's output while all the other amplifiers are in current limit and thereby inactive.

Abstract: A d.c. power supply system comprises a plurality of voltage regulating power supplies connected in a master slave configuration, the number of regulators being one greater than required to provide load current requirements. The master regulator generates a control signal to control the output of the individual slave regulators to provide balanced load sharing. Failure of one of the slave regulators is detected and the failed regulator replaced by the redundant regulator without interference to the output load current. Failure of the master regulator is detected by steering circuitry within each slave which senses an improper master error signal and transfers control to the reference error amplifier circuity of the slave regulators. Diagnosis of the error conditions is provided by logical analysis of output currents.

Abstract: A load share system which connects to the power outputs of two power supplies to determine any deviation of the output currents relative to each other and provides a correction signal representative of the deviation. The system generates two balance signals of similar magnitude and opposite polarity and delivers one of the balance signals to a sense input of one power supply and the other signal to a sense input of the other power supply to balance the power outputs.

Abstract: A power supply system includes a plurality of dedicated power supplies, each of which has a separate output terminal for furnishing output current to just one respective load. Each dedicated power supply has a switch for turning the supply on and off independent of the remaining dedicated supplies. A single redundant power supply is also included which turns on when every dedicated supply is on. And, a control circuit is included which shares output current from the redundant supply, when it is on, with the loads of only a subset of the dedicated supplies, such that the total shared output current from the redundant supply and the respective output current from each dedicated supply in the subset are all substantially equal. This subset consists of any dedicated supply which fails, and those dedicated supplies whose output current to their load when the redundant supply is off exceeds the equalized current.

Abstract: A power supply system comprises several power supplies, each of which has output terminals that are coupled in parallel to supply respective DC output currents at the same time to a single load. Each power supply also has a branch of a control circuit, and each branch from every supply is coupled in parallel to thereby form a complete control circuit. In these branches, control currents flow that cause the respective output currents from the several power supplies to equalize. Each power supply also has a circuit for automatically turning the supply off independent of the other power supplies when a component in the supply fails; and under such conditions, a switch in the control circuit branch of the failing supply automatically opens which prevents control current from flowing therein and enables the remaining supplies to share the added load.

Abstract: In a conversion system including a plurality of converter units connected to supply a.c. outputs to a load through a common bus, each converter unit includes a simulation bus circuit adapted to detect simulated lateral current between the converter units. Thus, testing of parallel operation control circuit can be executed easily, based on the simulated lateral current before paralleling the main circuit.

Abstract: Disclosed is a system of paralleled switching power supplies designed and controlled to have substantially identical output voltages and impedances so as to share the load equally. The output voltage of each supply is controlled to decrease linearly with increased output current, and the individual power supplies and their control circuits are designed and controlled to behave as identically as possible under the expected service conditions such that, under any given set of conditions, the output voltages and impedances of the several individual power supplies can be expected to be substantially identical and therefore they can be expected to share the load substantially equally. Provisions are made to make the control of the individual power supplies substantially independent of variations in the resistance of the power cables connecting them to the common load.

Abstract: A memory buffer is provided between a receiving system and a digital computer to provide an indication of the number of times pulses from the same source have been received in a predetermined interval of time upon interrogation of the memory buffer by the digital computer while such memory buffer continues to function without interruption during the interrogation process so that information from pulses received during such interrogation by the digital computer is retained.

Abstract: A method for controlling the voltage and the load distribution, as well as for synchronizing, of several inverters the outputs of which can be connected to a common bus bar in which, for each inverter, a simulated control variable is formed and is compared as to amplitude and phase with a reference voltage which is the same for all inverters.

Abstract: A plurality of conventional, parallel a.c. to d.c. to a.c. to d.c. converters are driven by a common a.c. source supply current to a common load. Each of the converters includes a controller for a pulse width modulated chopper; the controller determines the amplitude of d.c. current at the output terminals of the particular converter. Input terminals of each controller are responsive to the output voltage of the particular converter with which the controller is associated. A common controller for the controllers of the individual converters is responsive to the load voltage. The common controller varies the impedance of a single variable impedance connected in parallel to remote sense input terminals of the controller of each of the converters.

Abstract: A static converter equipment comprising at least two converters, each with a DC terminal; each converter having a load with a feeding point connected to the DC terminal of the converter, the converters being arranged to work in offset phase relation to each other. The feeding points are interconnected with impedance means with resistance of at least the same order of magnitude as the load resistance and an impedance at the most of the same order of magnitude as the load impedance.

Abstract: The invention relates to a power supply circuit utilizing a DC input tied to the primary windings of two transformers. A pulse source drives either primary through a selector switch which selects the desired primary to produce a pulsed transformer output of desired polarity. The transformer secondary windings produce a voltage output discharged by a load supplying capacitor. The voltage output is maintained at a desired polarity and at a peak level by periodically pulsing the load supplying capacitor with the same amount of energy taken by the load.

Abstract: A static power converter includes a plurality of thyristor bridges. The level of the control voltage is measured and a signal representative of the measured level is generated which causes one thyristor bridge to maintain a substantially zero output D.C. voltage, while another thyristor bridge operates with phase shift control.

Abstract: A method for regulating the work current of half circuits of a bipolar d.c. transmission line comprising a plurality of interconnected electric valve bridges in the half circuits with the aid of current regulators acting upon control electrodes of the electric valves in combination with changing the number of bridges connected to the half circuits, whereby a preselected transmitted power magnitude is ensured by putting into operation an optimum number of bridges and by the optimum setting of the current regulators, the number of the operating bridges and the work current magnitude in each half circuit being determined by minimizing the sum of the transmission power loss components which depend upon the number of operating bridges, the work current magnitude, and the operating voltage in the half circuits.

Abstract: Apparatus for converting the output of a high voltage D.C. source to a lower voltage and a higher current comprising a plurality of power conversion modules connected electrically in series across the D.C. source output so that each of the power conversion modules receives only a portion of the high voltage, each power conversion module including means for converting the high voltage portion to an A.C. signal and transformer means for reducing the voltage and increasing the current of such A.C. signal, the outputs of all of the transformer means being connected electrically in parallel. Each of the power conversion means includes a pair of capacitors which are charged by the high voltage D.C. source and which are alternately, periodically only slightly discharged to convert the D.C. voltage to an A.C. signal.