Abstract: An inverter includes an intermediate circuit, inverter bridge branches downstream of the intermediate circuit for outputting a power signal, and a controller operable for individually turning on and off the inverter bridge branches. The controller may individually turn on and off the inverter bridge branches as a function of an electrical quantity. The electrical quantity may be indicative of a voltage or a change in voltage occurring in the intermediate circuit during operation of the inverter. The electrical quantity may be indicative of the output power signal. The inverter bridge branches may include three inverter bridge branches.

Abstract: A multiphase current supplying circuit according to the present invention includes a diode bridge, an intervening circuit, an inverter, a control circuit, and a lightning arrester. The diode bridge is connected to a single-phase AC power supply system via the lightning arrester, and performs full-wave rectification on a single-phase AC voltage. The intervening circuit includes a capacitor and an inductor, and is constituted by a choke input type low-pass filter. More specifically, one end of the inductor and one end of the capacitor are connected, output from the diode bridge is received between the other end of the inductor and the other end of the capacitor, and a rectified voltage generated at both ends of the capacitor is output to the inverter.

Abstract: Consistent with an aspect of the present disclosure, a backup fuel cell, for example, is coupled to a utility power grid, through a power conversion circuit. The power conversion circuit may include an inverter circuit, pulse generating circuit and control circuit. The inverter circuit is configured to receive a DC signal and output a first AC signal, and the pulse generating circuit generates a pulse signal in response to a change in a parameter associated with a second utility generated AC signal. The control circuit is coupled to the inverter circuit, and is configured to receive the pulse signal. In addition, the control circuit supplies a control signal to the inverter circuit to adjust a parameter associated with the first AC signal in response to the pulse.

Abstract: A converter circuit for converting an output voltage from an AC power supply includes a rectifier circuit for rectifying the output voltage of the AC power supply; first and second capacitors connected in series, for smoothing the output of the rectifier circuit; and a switch circuit for switching the connections between the respective capacitors and the AC power supply so that the output voltage of the AC power supply is applied to each of the respective capacitors at a cycle that is shorter than the cycle of the AC power supply.

Abstract: A system and method are provided to increase the horsepower of an induction motor. One technique for increasing the horsepower of a motor is to connect the motor to a variable speed drive that is providing an output voltage and frequency greater than the standard line voltage and frequency. The connection of the variable speed drive to the induction motor enables the motor to be operated in constant flux or constant volts/Hz mode and provide a greater output horsepower. Another technique for increasing the horsepower of a motor is to use a dual voltage motor configured for lower voltage operation and then provide the motor with the corresponding voltage and frequency for higher voltage operation. The higher voltage and higher frequency can be provided by a variable speed drive with or without voltage boost. A variable speed drive without voltage boost, but with frequency boost, can be used in situations where the standard main voltage is greater than the lower voltage rating.

Abstract: A plurality of control power sources of voltage specifications different from one another are constructed. A generator output converted by a converter into a DC current is converted by an inverter into an AC current of a predetermined frequency. The generation output is rectified by second rectifier circuits and a capacitor and is then input to an RCC. The RCC constitutes a self-excited oscillation circuit, energy is stored into a transformer in an ON time of a transistor corresponding to an oscillation frequency thereof, and the energy is transferred to a secondary side in an OFF time. In the secondary side of the RCC, windings are formed corresponding to the number of required power sources. One group of windings forms both positive and negative power sources of a control power source, and another group of windings forms a power source for an FET driver.

Abstract: A method and a device for realizing an effective value of a quantity to be varied in an electrical load connected to a multi-phase switchable DC/AC frequency convertor comprising a plurality of controllable switches. The value is realized by varying a current or a voltage delivered by the DC/AC frequency convertor through suitable switching of the switches thereof, and wherein the quantity exhibits a load angle which, averaged in time, leads or lags the voltage or current being delivered.

Abstract: A system for controlling multiple vehicle includes a twelve volt (12V)/forty-two volt (42V) battery power distribution system that provides direct current. The system converts single phase alternating current to multiple phase alternating current to simultaneously power multiple vehicle systems. A single pulse width modulation generator converts the direct current from the 12V/42V battery power distribution system to alternating current. This provides one power supply path of alternating current, which has a first phase. A splitter device splits the one power supply path of alternating current into three power paths. A lead/lag circuit is used to shift the alternating current of the second path to a second phase different than the first phase of the first power supply path. A second lead/lag circuit for shifts the alternating current of the third path to a third phase different than the first phase or the second phase. This creates a three-phase alternating current power from a single direct current source.

Abstract: The present invention provides a control algorithm which instantaneously detects magnetic pole positions in the inside of a motor including polarities of the motor. A controller 1 applies a minute voltage change vhd to a voltage command on a dc axis which constitutes an estimation magnetic pole axis of the motor 3, detects electric currents Idc, Iqc of a motor 3 and discriminates the polarities of the magnetic pole axes by making use of the difference between a cycle in which ripple components of the electric currents Idc, Iqc become positive and a cycle in which the ripple components become negative or the difference between positive-side and negative-side current change rates. Further, the minute voltage change vhd with respect to the above-mentioned voltage command is generated on both of the dc axis and the qc axis rectangular thereto, and the magnetic pole positions of the motor are directly estimated based on the current ripple components on the respective axes.

Abstract: An input device for a computer system includes a housing and an output circuit located in the housing. The output circuit is capable of providing an output signal to the computer system that is indicative of movement of at least a portion of the input device. A physical feedback device is also located in the housing and is capable of stimulating a localized area of the housing in response to a signal from the computer system.

Abstract: Disclosed are a voltage compensating apparatus and method for a 3-phase inverter using four switches, to compensate for a severe distortion of a 3-phase application voltage due to a voltage ripple.

Abstract: A phase converter that converts single phase AC electric power to balanced three phase AC power. Two input terminal connected to the output of a single phase AC power source connect directly to two output terminals of the converter. The phase converter has two serially connected storage capacitors with a common connection, a charging circuit for controlled charging the storage capacitors and an output circuit for controlled discharge of the storage capacitors to provide single phase AC power to a third output terminal. The charging circuit controls input to the storage capacitor to provide a sinusoidal input current and to step up the voltage to the storage capacitors. The output circuit provides output power to the third output terminal of a predetermined phase and amplitude, relative to the other two output terminals, to result in balanced three phase AC power at the three output terminals.

Abstract: A method of controlling an electric power source apparatus including an electric power converter circuit which converts an output of an electric power source into DC or AC output and load connector terminals across which is applied an output of said converter circuit, which includes the steps of detecting a waveform of the load voltage across the load connection terminals after the output of the electric power converter circuit is stopped when an overcurrent flows through the load connection terminals, of judging a cause due to which the overcurrent flows, and of controlling said converter circuit according to the result of the judgement, wherein the electric power converter circuit is kept stopped when it is judged that the overcurrent is caused by an increase in the load and the electric power converter is so controlled that the waveform of the voltage applied across the load connection terminals from the electric power converter circuit is consistent with the waveform of the voltage detected by the voltage

Abstract: An apparatus for conversion of a three-phase voltage system into an electrically isolated DC voltage to be predetermined freely, and a method for controlling the same, include primary and secondary circuits. Each phase of the primary circuit has a series inductance connected to one input of a bidirectional, bipolar electronic switching apparatus. Second inputs of the switching apparatuses are directly connected. A positive primary voltage rail is fed through diodes, and a negative primary voltage rail is fed through other diodes. One winding end of a primary winding of a transformer is connected to a line connecting the second inputs of the switching apparatuses. A power transistor, which is connected to the positive primary voltage rail on the collector/drain side and has an antiparallel connected diode, is connected to another winding end of the primary winding.

Abstract: A device for converting current and voltage between a first single-phase side and a second single- or multi-phase side is provided. At least two converter modules are connected between these sides. Each converter module has two converters interacting with one of the sides and an intermediate link interconnecting them. The converter modules are connected in series on the first side.

Abstract: A three-phase invertor and control is disclosed for synthesizing low harmonic content AC voltage in the non-linear, or overmodulation, region of inverter operation. A field orientation control provides a reference voltage vector representing the desired AC output voltage in magnitude and angle. Three state, two state, and step inverter operations are used individually and in combinations in accordance with magnitude and angle parameters of the reference voltage vector.

Abstract: The present invention discloses a method for providing balanced power to a single-phase ac load from a three-phase ac power source. The method includes imposing an isolation power transformer between the ac power source and the load wherein the isolation transformer has a three-phase primary winding and a six-phase "wye" connected secondary winding, at least one of the three legs of the secondary having a center tap and being connected to the load such that the center tap provides a reference potential for the load and the reactive load currents are equal and inversely-phased with respect to the reference potential.

Abstract: A converter for providing three phase power to a three phase load from a single phase supply includes an inverter connected to single phase input power lines and a bi-directional switch connected in series with one of the input power lines. The converter has three output lines, one connected to the inverter output, another connected to an input power line between the bi-directional switch and the inverter, and the third connected directly to the other input power line. The inverter switching devices are controlled to provide a signal on the output of the inverter to provide balanced three phase power on the converter output lines. This is preferably accomplished by pulse width modulation of an inverter output voltage reference signal derived by phase shifting the single phase input voltage signal by 60.degree.. The inverter is preferably also controlled to phase shift the inverter output signal when necessary to ensure that the net power flow into the inverter is zero under light load conditions.

Abstract: A symmetrical ac power system provides a balanced ac output, whose maximum voltage with respect to a reference ground potential is one-half the ac output voltage, and which is derived from a single phase ac source through the use of an isolation transformer having a center-tapped secondary winding. The center tap is connected to the output power load circuit as a ground reference potential with respect to the symmetrical ac output so as to constitute the reference ground potential for the power supply and load. Since symmetrical ac power is applied to the load by the system, reactive load currents, other power artifacts, EMI and RFI emissions and other interference and noise components ordinarily resulting from the application of conventional ac power to the load are reduced or eliminated by appearing as equal inversely phased signal elements which cancel one another. In order to maximize the performance of the symmetrical power system, the isolation transformer has a bifilar-wound secondary winding.

Abstract: An air conditioning device is arranged such that an output voltage from a commercial power source is converted into a direct current by a rectifying circuit and a smoothing condenser. Thereafter, it is further converted into an AC voltage having a variable frequency by an inverter under the control of a microcomputer, thereby supplying it to a power compressor. Between the rectifying circuit and the smoothing condenser, an active filter is provided for shaping an input current to be an approximate sine wave almost in phase with an input voltage by switching a power transistor. The switching control section and the microcomputer for controlling the switching are activated independently by separately provided power sources. The switching control section supplies a high level signal when the active filter is a normal condition, and supplies a low level signal when the active filter is abnormal.

Abstract: A symmetrical ac power system provides a balanced ac output, whose maximum voltage with respect to a reference ground potential is one-half the ac output voltage, and which is derived from a single phase ac source through the use of an isolation transformer having a center-tapped secondary winding. The center tap is connected to the output power load circuit as a ground reference potential with respect to the symmetrical ac output so as to constitute the reference ground potential for the power supply and load. Since symmetrical ac power is applied to the load by the system, reactive load currents, other power artifacts, EMI and RFI emissions and other interference and noise components ordinarily resulting from the application of conventional ac power to the load are reduced or eliminated by appearing as equal inversely phased signal elements which cancel one another. In order to maximize the performance of the symmetrical power system, the isolation transformer has a bifilar-wound secondary winding.

Abstract: A semiconductor switching circuit is connected to a DC power source for an inverter to control a servomotor in an injection molding machine, and a PWM signal controls an ON/OFF operation of a switching device in the semiconductor switching circuit so as to feed power to a heater of the injection molding machine. Since the DC power source feeds the heater with power, it is possible to overcome irregularity in power supply, and linearly vary a conducting time, thereby finely and accurately controlling a temperature. The DC power source for the inverter to control the servomotor also serves as a DC power source for the heater, resulting in no need for a special power source circuit.

Abstract: An inverter power supply for use with various voltage inputs is provided. The inverter power supply generally receives 208 VAC single-phase, 208 VAC three-phase, 230 VAC three-phase, 230 VAC single-phase, 460 VAC single-phase, or 460 VAC three-phase power and provides a DC output current for welding, heating or cutting applications. The power inverter circuit includes a first tank circuit and a second tank circuit which are configured in serial or parallel according to a particular voltage input. Contactors, relays, or semiconductor switches respond to control signals from an AC sense circuit in order to configure the inverter power supply for the appropriate voltage input.

Abstract: An inverter power supply for use with various voltage inputs is provided. The inverter power supply generally receives 208 VAC single-phase, 230 VAC three-phase, 230 VAC single-phase, 460 VAC single-phase, 208 VAC three-phrase or 460 VAC three-phase power and provides a DC output current for welding, heating or cutting applications. The power inverter circuit includes a first tank circuit and a second tank circuit which are configured in serial or parallel according to a particular voltage input. Contactors, relays, or semiconductor switches respond to control signals from an AC sense circuit in order to configure the inverter power supply for the appropriate voltage input.

Abstract: A drive control apparatus for controlling a motor to drive the compressor of an air conditioner, according to the present invention, includes a rectifying circuit for converting an AC voltage into a DC voltage, an inverter having a combination of a plurality of power controlling semiconductor devices and which controls the DC voltage from the rectifying circuit in accordance with a drive signal supplied to the combination of the semiconductor devices so as to generate an AC drive current to the drive, and a drive circuit for generating the drive signal to the inverter. The drive circuit formed as a monolithic integrated circuit having a dielectric separation structure, with the monolithic integrated circuit and the inverter being mounted on a common module substrate.

Abstract: The invention relates to a process for compensating a phase and amplitude response between a multiphase setpoint and actual value (i.sub.Rw, i.sub.Sw, i.sub.Tw and i.sub.Rx, i.sub.Sx, i.sub.Tx), the first step being to determine the modulus setpoint value (.vertline.i.sub.w .vertline.) or modulus actual value (.vertline.i.sub.x .vertline.) and the angular setpoint value (.epsilon..sub.w) or angular actual value (.epsilon..sub.x) of the setpoint or actual value vector (i.sup.w or i.sup.x), a modulus manipulative variable (.vertline.i.sub.wxy .vertline.) and an angular manipulative variable (.epsilon..sub.wxy) then being generated by modulus and phase from a modulus deviation (.vertline.i.sub.w .vertline.-.vertline.i.sub.x .vertline.) and an angular deviation (.epsilon..sub.w -.epsilon..sub.x) which are added by modulus and phase to the output quantities (.vertline.i.sub.w .vertline., .epsilon..sub.w) of the setpoint value vector computer (26), these modulus and phase sums (.vertline.i.sub.Kw .vertline.,.

Abstract: In a power unit, an output current supplied from the power unit to a load device is constantly detected as a load current. When the detected load current exceeds a predetermined current value, output power supplied from the power unit to the load device is reduced or cut off. An output voltage supplied from the power unit to the load device is constantly detected. When the detected output voltage has continued to be lower than a predetermined voltage value over a predetermined time period, the output power is reduced or cut off.

Abstract: An apparatus for converting single phase input power to three phase output power supplied to a motor includes a pair of input lines, and a pair of DC bus lines, a pair of capacitors, a pair of diodes, and a pair of controlled switching devices which are each connected between the DC bus lines. One of the input lines is connected to the node between the capacitors and the other input line is connected to the node between the diodes. Two output lines are connected to the input line and a third output line is connected to the node between the two switching devices, with the three output lines being connected to a motor to supply three phase power to the motor. The switching devices are switched in a pulse width modulated manner to provide a voltage between the third output line and the other two output lines which provides the three phase power. During motor startup, at least one startup capacitor is switched in between one or both of the input lines and the output lines to provide startup torque for the motor.

Abstract: An engine-driven power generating system having a bridge circuit section in which low-frequency switching elements are driven alternately by low-frequency drive signals, and high-frequency switching elements driven by high-frequency drive signals during the ON period of the low-frequency switching elements are connected in a bridge network, and an inverter circuit section having a drive signal supply circuit for supplying low-frequency and high-frequency drive signals are each supplied to the low-frequency and high-frequency switching elements that form a pair; the a-c voltage generated by an engine-driven a-c generator is converted into d-c voltage that is in turn converted into a predetermined level of low-frequency a-c voltage; characterized in that an overcurrent detecting circuit for detecting an overcurrent flowing in the bridge circuit section at a level higher than a predetermined level, a drive-signal control circuit that outputs to a drive-signal supply circuit, when the overcurrent detecting circui

Abstract: A system for discharging electrical power from a high-voltage direct-current (HVDC) transmission line to a local network, utilizes a first, single-phase converter bridge comprising semiconductor switches which are energized by signals and which are de-energized solely with current zero crossing, and a first, single-phase transformer having a primary winding connected to a HVDC line and a secondary winding; a second converter bridge connected to the secondary winding; a secondary direct voltage network connected to the second converter bridge; a third converter bridge connected to the secondary direct voltage network for generating an alternating current for the local network; and the second and the third converter bridges each comprise ON/OFF controllable semiconductor switches, and the first and the second converter bridges commutate with a frequency that is 2-4 times higher than the normal frequency of the local network and the third converter bridge commutates at the normal frequency of the local network.

Abstract: A power converter apparatus for an electric train, including at least a first modular power converter unit having a main circuit formed of switch for interrupting power from a D.C. power source, a first D.C.-A.C. power converter connected to the switch, an isolation transformer connected between the D.C.-A.C. power converter and a rectifier and a second D.C.-A.C. power converter connected to the rectifier. The switch and the first D.C.-A.C. power converter are controlled by a control signal derived from the difference between the output voltage of the first D.C.-A.C. power converter and the sum of a delayed soft starting control signal and a settable reference signal. The second D.C.-A.C. power converter is pulse width modulated. Preferably a second modular power converter unit having the same construction as the first unit is provided and has inputs connected in series or in parallel with inputs of the first unit.

Abstract: An electronic system comprises a three-phase transformer, a power conversion circuit, and a control circuit. The three-phase transformer has primary windings and first, second and third secondary windings. The primary windings are connected to three-phase power supply and the first secondary winding is connected in phase with a single-phase load, such as an electric railway. The second and third secondary windings are connected to the single-phase load by the power conversion circuit. The power conversion circuit includes an a.c. to d.c. converter, a d.c. to a.c. converter, and a single-phase transformer. The d.c. to a.c. converter is adapted to convert out of phase power from the second and third windings, into a d.c. voltage signal. The d.c. to a.c. converter is connected to a.c. to d.c. converter and is adapted to convert the d.c. voltage signal into a single-phase a.c. voltage signal. The single-phase transformer has a primary winding which is connected to the d.c. to a.c.

Abstract: A three phase A.C. to single phase A.C. converter wherein the output voltage is not disturbed if one of the input phase lines becomes inoperative. The three phase A.C. is first rectified, and a D.C. voltage is derived from the resulting rectified D.C. current. The D.C. voltage is regulated, and a single phase A.C. voltage is generated from the regulated D.C. voltage.

Abstract: A resonant, quasi-square wave, pulse width modulated (PWM) power source (33) for a connectorless power system is disclosed. The power source (33) supplies constant amplitude, fixed-frequency current to a supply loop (31) that is inductively coupled to a plurality of pickup loops (35), each of which supplies power to a remote unit, such as the seat regulator that supplies power to a group of commercial airplane seats (37). Precise, fixed-frequency control is provided by triggering a PWM with fixed-frequency sync pulses. Current control is provided by sensing the current applied to the supply loop, converting the magnitude of the sensed current to a voltage and using the voltage to control the width of the pulses produced by the PWM. The PWM pulses, in turn, control the width of the power pulses applied by the power source (33) to the supply loop (31). Stability and efficiency are improved by maintaining the output of the power source nearly resonant, i.e.

Abstract: A three phase alternator is driven by a variable speed prime mover, and its rectified output is pulse width modulated by a gate controlled H-bridge power switch circuit. Predetermined pairs of power switches are gated on and off according to programmed duration and timing instructions contained in a read only memory. In a first embodiment, a sine wave output is produced by successive pulse trains. The first pulse train has alternating positive and negative constant amplitude pulses, with the widths of positive pulses varying sinusoidally and the widths of negative pulses being constant. The second pulse train has alternating positive and negative pulses of constant amplitude, with the pulse widths of the negative pulse components varying sinusoidally, and the pulse widths of the positive components being constant. The components of the first and second pulse trains have an energy distribution which corresponds to one cycle of a sine wave having a fixed frequency.

Abstract: An electric floor cleaner is of the type arranged to drive a three-phase motor, whose rated voltage is substantially equal to a voltage obtained by voltage doubling and rectifying a single-phase commercial power line and then by converting a voltage doubled d.c. voltage into three-phase a.c. by an inverter. The voltage and frequency of the three-phase a.c. output from the inverter are controlled for a predetermined period of time after a power switch is put into a turned on state from a turned off state. It is therefore possible to reduce the starting current to a small value enabling the use of a larger rated output motor than a motor in a conventional system within an allowable current limit of a commercial power line.

Abstract: In a power converter apparatus, variations contained in a single-phase AC input voltage cause a beat phenomenon in a three-phase DC/AC inverter. To avoid such a beat phenomenon, the single-phase AC input voltage is converted into a DC input voltage having ripple components and the ripple components are filtered from the input voltage so as to derive an input DC voltage. The input DC voltage is inserted into a three-phase AC voltage. Variations contained in the single-phase AC input voltage are detected to obtain a variation detecting signal and the inversion is controlled in a pulse width modulation control mode based upon the variation detecting signal and a reference signal.

Abstract: A power supply for negative impedance discharge loads such as discharge tubes used in gas laser systems, in which the discharge power is supplied not from the voltage source but from the current source through the current transformer so that stabilized and well balanced discharge currents can be supplied to a plurality of discharge loads.

Abstract: Three-phase power-conversion wherein the frequency output voltage is independent of the frequency of input voltage. One of three input terminals in a load powered by the apparatus is directly grounded. Each of the other two input terminals is supplied a sinusoidal voltage artifact from an appropriate transform circuit which is driven by a microprocessor, with one of these artifacts having a form 1.73.alpha.SinA, and the other having the form of 1.73.alpha.Sin(A+60.degree.), where .alpha. is the nominal amplitude of the source voltage and the Expressions A and (A+60.degree.) are the respective phase angles. Operation of the microprocessor controls output frequency.

Abstract: Apparatus for supplying from a single-phase, known-frequency AC source, three-phase AC power at the same frequency. The apparatus features circuitry which employs high-speed power switching with respect to only one phase of a three-phase load, with the result that only two high-speed power-switching devices (transistors) are required.

Abstract: Device for supplying power from a three-phase network to an ozonizer comprising at least two discharge elements (3, 4) having a capacitive character, and comprising two single-phase step-up transformers (1, 2) having air gaps connected in a SCOTT circuit and connected between the three-phase network and said discharge elements (3, 4). The device further comprises a three-phase transformer (8) whose secondary windings (5, 6, 7) are connected between said single-phase transformers (1, 2) and the three-phase network and whose primary windings (9, 10, 11) are star-connected and connected to the three-phase network through a dimmer (12).

Abstract: A regulated chopped DC power supply comprising an alternator with a stator and a rotor, the alternator having a three-phase winding for providing a high voltage output (1, 2, 3) and a star-connected three-phase winding for providing a low voltage output. Also included is a control circuit (14) for controlling a rectifier (12) which is connected to the high voltage output (1, 2, 3) of the alternator to produce a regulated chopped dc output (52) for powering electrical appliances. The control circuit (14) periodically interrupts the rectifier (12) at a frequency to interrupt substantially simultaneously all of the phases of the high voltage output.

Abstract: An apparatus for converting a single phase electrical signal into a three phase electrical signal is disclosed. A converter includes a rectifier connectable to a single phase electrical power source. One output of the rectifier is connected through a smoothing ciruit to four switching transistors. The other output of the rectifier is connected to center taps of a first and a second load coil. The first phase load coil is connected across a first pair of the switching transistors and the second phase load coil is connected across a second pair of the switching transistors. Third and fourth phase load coils are connected to opposite sides of the first and second phase load coils. The first, second, and third phase load coils are delta connected and the first, second, and fourth phase load coils are delta connected. The first and second pairs of switching transistors are controlled by first and second pairs of phase shifting signals.

Abstract: The invention relates to a parallel resonant-circuit converter having at least one intermediate-circuit inductance. In order to guarantee that the inverter will start even with different loads, the voltage produced when discharging a separately charged capacitor across the load is monitored. At some time after the maximum voltage across the load is reached, another separately charged capacitor is discharged via a thyristor of the inverter located in the biasing circuit of the intermediate-circuit inductance. Because of the blocked thyristor and of the capacitor charged to the voltage maximum, the biasing current is forced to flow via diagonal branches and including the load. In this manner, reliable starting of the inverter is possible even with loads having a different natural frequency.

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 power supply system generates a.c. power which is applied through a high voltage transformer to the electrodes of a treater. It includes a converter circuit which transforms a.c. electric power to d.c. power and an inverter which transforms the d.c. power to a.c. power. A feedback circuit senses the power delivered to the treater and separate control of both inverter frequency and output voltage is employed to prevent arc-over during the treatment process. The power supply system is particularly responsive to sudden changes in the operating conditions, and this enables treatment of relatively thin materials on a bare metal roller.

Abstract: A rectifier controller for controlling bridge connected silicon control rectifiers (SCRs) (1 to 6) of a three-phase rectifier which is used to supply a direct current (DC) voltage to an inverter (314) used for injecting pulse coded audio frequency signals on a power line. The controller supplies gate control signals to the SCRs (1 to 6) of the rectifier bridge in accordance with the envelope of the three-phase supply voltages and provides for protection of the inverter (314) when shoot-through conditions occur in the inverter (314) and provides for output DC voltage adjustment by controlling the firing time of the rectifier bridge SCRs.

Abstract: A variable frequency oscillator for an AC power supply having programmable, multiple phase outputs comprises means including a rate multiplier for generating a clock signal having a selectively controllable frequency and one or more AC signal producing stages responsive thereto. Each AC signal producing stage includes a memory storing a quarter-cycle sinusoidal waveform segment in amplitude sampled form and an address counter responsive to the clock signal for alternately addressing the memory in forward and reverse directions for producing a continuous sequence of half-cycle sinusoidal segments, an output circuit inverting every other one of the half-cycle segments.

Abstract: A static convertor with forced commutation is connected between an alternating voltage network and a direct voltage network. A filter is connected in parallel with a smoothing capacitor on the DC side of the convertor. The filter consists of the series-connection of an inductor, a filter capacitor and two controllable semiconductor valves that are connected in parallel in opposed relation. The natural frequency of the filter is higher than the product of the frequency of the alternating voltage network and the pulse number of the converter. The valves are made to carry current in time with the fundamental tone of the AC component present in the direct current of the convertor. In this way, the variations of the direct voltage of the convertor, caused by the AC direct current component, may be practically eliminated.

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.