Abstract: The DC content of each phase of a three phase AC waveform is generated by partially filtering each phase and applying the filtered waveforms sequentially through a multiplexer to a sample and hold circuit which measures the instantaneous value of each phase at two points which are spaced an exact odd number of half-cycles apart. These instantaneous values are fed by an analog to digital converter into a microprocessor which averages the two readings to generate the DC content for each phase and compares the highest DC content with a threshold value. The excess of the highest DC content over the threshold value is integrated and an output signal is generated when the accumulated volt-seconds exceed a selected value.

Abstract: The non-linear control characteristic of a force commutated current source inverter operating as a var generator is linearized to provide a similar dynamic response in both leading and lagging modes of operation by two inter-related control schemes. The first control scheme comprises a linear closed loop feedback which controls a thyristor firing circuit in response to a difference or error signal between a var command signal and an actual var feedback signal while the second control comprises a feed-forward non-linear network having a signal transfer function which models the non-linear control characteristic of the var generator and is operative to control the thyristor firing circuit in response to the summation of scaled values of the var command signal and the actual var feedback signal and wherein the scaled values provide a combined gain which is equal to unity.

Abstract: A series inverter, high voltage capacitor charging circuit includes a current sensor for sensing the current through the load circuit. The sensed current is used to vary the gating frequency of SCRs and to preclude firing of an SCR pair until another SCR pair is in a stable off condition. The gating of each SCR pair is delayed by an amount of time determined by a control capacitor charging circuit. That charging circuit is inhibited as long as one of the SCRs is conducting and once the load voltage has reached a predetermined level. The time constant of that charging circuit is longer if insufficient reverse bias is applied to an SCR for quick turn-off of the SCR. The current sensing thresholds of common base transistors depend on whether forward or reflective current is being sensed. A series capacitor in the load circuit is discharged prior to a first cycle of current flow from the dc supply.

Abstract: An energy converter comprising a series-resonant bridge circuit (1) tuned to a constant frequency. A number of parallel-connected output transformers (2, 3) are accommodated in the bridge circuit and energy buffers (6, 7) are coupled to the secondary winding of each of the output transformers. By means of control circuits (23, 24) activated by the voltage across the different energy buffers the current through the primary winding of a relevant output transformer is controlled so that the voltage across the corresponding energy buffer remains constant.

Abstract: An energy converter comprising a series-resonant bridge circuit (1) containing at least two thyristors (6, 7), first and second respective diodes (8, 9) connected antiparallel thereto, a high-frequency output transformer (23), and an energy buffer (2). A control circuit (20) is incorporated for generating trigger pulses for the appropriate thyristors in response to the energy of the buffer (2). The energy converter comprises means for ensuring that the diode, antiparallel connected to the last-conducting thyristor, starts to draw current immediately after this thyristor is blocked. The control circuit also generates signals indicative of the presence of current flowing through the diodes (8, 9), which signals control the supply of the trigger pulses to the thyristors (6, 7).

Abstract: A system for forming address signals which address respective converter switches in a frequency converter. The frequency converter is of the type wherein a DC voltage is provided for supplying electrical energy to phase outputs thereof in response to the states of the converter switches. In accordance with the invention, the phase output voltages, phase output currents, and predetermined desired phase currents are treated as space vectors from which are generated control difference space vectors. In one embodiment, a trigger pulse is generated externally and may be suppressed when the control difference vector has a value which is below a preselected tolerance limit. In a further embodiment, the trigger pulse is generated internally and is suppressed if the tolerance limit is exceeded. Upon the occurrence of each trigger pulse, a voltage space vector is addressed having a direction which is opposite to the control difference space vector.

Abstract: An inverter system having a plurality of resonating current supplying stages connected in parallel, all resonant at the same frequency. The rate at which the stages operate is controlled by a feedback circuit responsive to the load output. The rate is maintained above the audible range for all but small total current values. Should the rate tend to vary outside a predetermined range, a different combination of stages is switched in. The stages supply currents which are binary weighted.

Abstract: In a converter comprising gate turn-off thyristors, a current at an A.C. part of the converter is detected and a polarity of the detected current and a magnitude of the detected current is checked to determine if it is below a holding current level for maintaining the gate turn-off thyristors on. If the detected current is below the holding current level, a pulse width modulated signal is produced as a gate signal. If the detected level is above the holding current level, a short duration pulse synchronized with a rise and a fall of the pulse width modulated signal is produced as the gate signal. The gate signal is supplied to only those of the gate turn-off thyristors which correspond to the polarity of the detected current.

Abstract: A dc-dc converter employs a series resonant circuit which is driven by square waves of current. By adjusting the frequency of the square waves of current above the resonant point or by holding the frequency constant and varying the current supplied to the converter, the voltage on the resonant components can be stepped up and controlled. Switching losses in the inverter gate turn-off devices are low since the inverter feeds a lagging load which allows the use of lossless snubbers.

Abstract: A control unit for DC-to-AC inverter having an addressing memory which is loaded with an addressing table by a microprocessor for a respective frequency range of the inverter output voltage. In the addressing table, a predetermined portion of information is provided for each addressing combination of the switches of the DC-to-AC inverter, the portion of information containing the addressing combination itself and the number of clock pulses for which the addressing combination will be present. The portions of information are interrogated at different speeds depending upon the desired inverter output frequency. A frequency divider is addressed by a clock generator, the frequency divider receiving a division factor from the memory, the division factor being inversely proportional to the desired DC-to-AC inverter output frequency. The output signal of the divider decrements a counter which is loaded with a number of clock pulses associated with the respective addressing combination.

Abstract: A dc-dc converter employs a parallel resonant circuit which is driven by square waves of current. By adjusting the frequency below the resonant point, the voltage on the resonant components can be stepped up. Switching losses in the inverter devices are low since the inverter feeds a lagging load allowing lossless snubber operation which allows the use of lossless snubbers.

Abstract: A pulse width modulation inverter loaded with a three-phase AC motor is halted when a logical condition exists that a halt signal has been given and all of pulse width modulation signals applied to either three positive side or three negative side main thyristors in a three-phase bridge connection constituting the inverter are in their high level states.

Abstract: An induction heating system (40) is provided and includes a plurality of induction heating coils (118). Touch control pads (50, 52, 70, 72) are provided together with circuitry (80) for generating energization control signals. Circuitry (112, 116) is provided for electrically energizing the induction heating coils (118). An electronic digital processor (82) is responsive to the energization control signals for generating energization signals for actuating and controlling the energization circuitry (112, 116) to thereby vary the energization of the plurality of induction heating coils (118).

Abstract: The DC to AC power inverter is of the class B, C, D or E type and includes a battery, at least one power SCR and associated capacitor circuitry, at least one input winding on a main transformer core and at least one output secondary winding on the transformer core. Such inverter requires a quiescent current to establish operating current for capacitor commutation charge and includes a feedback loading circuit for feeding current generated by the quiescent current back to the battery. The inverter also includes a self-detecting load demand circuit coupled to a line from said output winding for cyclically energizing the inverter, for sensing a minimum AC load and for holding said inverter in an energized state until less than a minimum AC load is sensed during an energizing cycle.

Abstract: An induction heating apparatus which includes an induction coil with an associated load and a resonant inverter circuit coupled to a DC power supply for energizing the heating coil. The inverter circuit includes a gate controlled thyristor which is cyclically gated to produce a conductive first period followed by an nonconductive second period in order to energize the heating coil. A diode of opposite polarity to the gate controlled thyristor is coupled in parallel therewith and has an impedance connected in series. The voltage across this series impedance is coupled to the gate of the gate controlled thyristor. The inverter circuit additionally includes an improper load check circuit for disabling the gating of the thyristor in the event of an improper load coupled to the heating coil, and a gate triggered timing generator for adjusting the timing of production of thyristor gate pulses to maintain substantially constant power to proper heating coil loads.

Abstract: A stabilized power supply which is particularly suitable for use at very high voltages derives its energy from a resonant inverter feeding a transformer and rectifier. The power supply is intended to be operated in a pulsed mode with the generation of each pulse reducing the output voltage below its required value. The output capacitive stages of the power supply are subsequently re-charged and an input switch is rendered non-conductive when the output voltage regains its required value. As it is not possible to switch off a resonant inverter during the course of a cycle, the energy obtained from the inverter during the remainder of the current cycle is fed into another capacitive stage. The second stage may also be utilized as an unregulated output rail of the power supply. The invention is particularly suitable for power travelling wave tube amplifiers.

Abstract: In a commutation control device for a current type inverter, a device for detecting voltage of a commutation capacitor and a device for controlling a charging interval of the capacitor are provided. The voltage detecting device includes a comparator, while the charging interval control device includes a timing pulse generator, a circuit for delaying a pulse delivered from a pulse generator, and a timing signal generator which delivers a timing signal adapted to control a discharge interval of the commutation capacitor for restricting the voltage thereof in a predetermined range.

Abstract: The effect of commutation notches 35 appearing in the nominally sinusoidal alternating current (AC) line-to-line voltage, for example, v.sub.ab used to synchronize the firing of thyristors in three phase, phase-locked power converters 12 and 14 is essentially eliminated by reconstructing the corrupted line-to-line voltage by summing the integral of the corrupted line-to-line voltage .PSI..sub.ab with a signal proportional to the product of the delta load current, for example, i.sub.ab and the commutation inductance L.sub.c. The composite waveform .PSI..sub.ab +i.sub.ab .times.L.sub.c) resulting from the summation has well defined zero crossings 41 from which synchronizing pulses are generated for synchronizing the phase-locked thyristor firing circuit 18 implemented by either software or hardware techniques. Additionally, the reconstructed waveform is used to control commutation, particularly in the control of a load side converter i.e. inverter 14 which is utilized in an AC motor drive system.

Abstract: An induction heating apparatus including a thyristor adapted to receive power from a power source, a gating control circuit for generating gating pulses for application to the gating control terminal of the thyristor, a commutating circuit which commutates off the thyristor, and a differentiator connected across the anode and cathode terminals of the thyristor to detect the power consumption of an inductively heated cooking ware. The gating control circuit comprises a gating pulse generator and a smoothing circuit for filtering the signal from the differentiator into a d-c signal which is compared with a reference level to detect the deviation of the power consumption from the reference value. The gating pulse generator is responsive to a potential at the anode of the thyristor to initiate timing action to determine the interpulse period or turn-off time of the thyristor and also responsive to the deviation of power consumption to vary the interpulse period.

Abstract: An auto-stabilized high power current generator which comprises a controllable frequency oscillator connected to a rectifier by means of a circuit including, in series, an induction coil, a measuring circuit developing a signal representing the current flowing between the oscillator and the rectifier, and a comparator for comparing the measuring circuit signal with a reference signal, and which controls the frequency of the oscillator to cause an increase therein when the measuring circuit signal exceeds the reference signal. The frequency of the oscillator is regulated by a switching circuit controlled, in the event the detected signal is less than the reference signal, by a timing device, and in the event the detected signal is higher than the reference signal, by the pulses delivered by the comparator. The invention is particularly applicable for supplying power to a process involving a discharge in a rarified gaseous atmosphere.

Abstract: There is provided an improvement in a power inverter for converting D.C. voltage into an alternating voltage by alternating gating D.C. current across a load. This type of inverter employs a gating circuit for providing gating signals in two sets of switches at a frequency which controls the power factor of the voltage and current applied to the load, means for detecting the power factor, means for comparing the detected power factor with a reference signal indicative of a desired operating power factor and means for adjusting the frequency in accordance with the comparison whereby the power factor tends to be at the desired power factor level. The improvement in this type of inverter is the provision of means for changing the reference signal during the operation of the inverter in accordance with a control signal so that the desired power factor can be changed during start up of the inverter.

Abstract: A push-pull switching dc-to-dc converter using controlled rectifiers as switch elements delivers uninterrupted output current to its load, owing to the inclusion of plural-winding inductors.

Abstract: An inverter arrangement for generating a three-phase AC output voltage is provided with three pulse-controlled, free-running single-phase inverters. The inverters are connected at their inputs to a DC voltage source, and at their outputs to respective low-pass filters. The low-pass filters are connected to corresponding single-phase transformers, each having an output winding. The output windings of the single-phase transformers are connected to one another in a Y-circuit configuration to produce the output AC voltages, having a grounded neutral terminal. Each of the single-phase inverters is controlled by an associated pulse control device which contains a vector-oriented control device and a control unit. A vector oscillator generates signals corresponding to a symmetrical three-phase system of reference vectors for the vector-oriented control devices.

Abstract: A series inverter, high voltage capacitor charging circuit includes current sensors for sensing the current through each SCR in the circuit. The sensed current is used to vary the gating frequency of the SCRs and to preclude firing of an SCR until the other is in a stable off condition. The gating of each SCR is delayed by an amount of time determined by a control capacitor charging circuit. That charging circuit is inhibited as long as one of the SCRs is conducting and once the load voltage has reached a predetermined level. The time constant of that charging circuit can be changed as the desired level is approached.

Abstract: An induction heating cooking apparatus comprises a self-controlled inverter which comprises a series connection of an induction coil and a switching element, a resonance capacitor connected in parallel with the switching element, and a flywheel diode. An inverter driver circuit triggers the inverter with a starting pulse obtained from a starting signal generator. A voltage signal associated with a current flowing through the switching element is obtained by means of a current transformer. A voltage source of the inverter is implemented as a ripple current voltage source. A comparator of a gate signal generator compares a reference level changing in accordance with the ripple current voltage and the voltage detected by the current transformer, thereby rendering the switching element non-conductive when the voltage level reaches the reference level.

Abstract: An LC series resonant regulator is connected across the output of the inverter circuit of a static converter apparatus to vary the output voltage level as the inverter operating frequency varies from a preselected frequency at which the regulator circuit is tuned. The load is coupled across the capacitor element of the regulator and a level detector coupled across the load input. This detector registers variations of the input to the load from a predetermined desired level of load voltage and supplies a feedback signal, indicative of any detected variations, to the control circuit for the inverter circuit element. This control circuit is responsive to a feedback signal to vary the operating frequency of the static inverter so that the regulator varies the output voltage applied to the load to restore the desired voltage level.

Abstract: A circuit arrangement to provide a fixed voltage source in series with an arbitrarily chosen impedance of any magnitude and phase shift having very low power dissipation and capable of being fabricated on silicon integrated chips is disclosed. The circuit arrangement includes a sensing resistor to sense the output current of a power converter which is amplified and fed back with an appropriate phase shift to control the output voltage of the converter. An independent control signal may be combined with the fed back voltage to change the chosen impedance to another type of impedance.

Abstract: In order to energize a load with an output current generally conforming to a control voltage, trains of firing pulses are alternately applied during respective conduction intervals of a recurrence period to a pair of main thyristors connected to opposite terminals of a balanced power supply which may be a DC source. The main thyristors are quenched, at the ends of their respective conduction intervals, by ancillary thyristors which lie in series with a resonant circuit including a commutating capacitor and alternately receive firing pulses in continuous succession in order to keep that capacitor operatively connected at all times to one or the other terminal of the power supply. The transmission of firing pulses to the several thyristors is timed by a logic circuit under the control of a comparator to which the control voltage is fed together with a sawtooth voltage establishing the aforementioned recurrence period.

Abstract: A phase adjustment circuit for sensing the phase of the signal at the output of an inverter and for providing a signal to the control circuits of the inverter whose phase has been offset by a preselected amount. The phase adjustment circuit includes a zero crossover detector for sensing the crossover points of the inverter output voltage. A phase-locked loop includes a phase comparator which receives the signal indicating the zero crossover points and a feedback signal from a phase shifter. The output of the phase comparator is an error signal which is integrated and presented to a voltage controlled oscillator to change the phase of its output signal. The phase shifter combines the phased waveform out of the voltage controlled oscillator with a command signal indicating the desired phase offset to form a feedback signal for presentation to the phase comparator closing the feedback loop.

Abstract: A power supply includes an inverter circuit comprising silicon controlled rectifiers which are driven by a variable frequency control signal. The frequency of the control signal is determined by monitoring the power output requirements of the power supply. Because of the continuous sinusoidal operation of the inverter, the supply generates a very low level of radio frequency interference (rfi).

Abstract: A three phase current inverter has a commutation circuit wherein a blocking voltage is generated which is applied from the anode to the cathode of the main control thyristors. The load current from the then-conductive phase is simultaneously transferred to the commutating or disconnect circuit. A separate accumulation circuit including a capacitor then takes over the load current, the energy stored in the load inductance being transferred to the capacitance in the accumulation circuit. The control thyristor for the next phase is switched to the conductive state, current is transferred from the accumulation circuit to the subsequent output phase and from the load of the first phase to the load of the second phase. The capacitor in the disconnect circuit is smaller than that in the accumulation circuit so that optimum characteristics for both circuits are obtained.

Abstract: An inverter device for converting DC to AC by using thyristors as switching elements comprises a commutation circuit for turn-off of the thyristors which is formed by a serial connection of an auxiliary power source, a gate control thyristor and a thyristor which is commonly used and connected to a thyristor used as the switching element which is turned off by applying a reverse voltage by turning on the gate control thyristor and the thyristor of the commutation circuit.

Abstract: A fixed gating sequence apparatus and method for an inverter is disclosed. In one aspect of the invention, an outgoing signal of variable frequency is generated by the inverter in response to gating signals provided by an inverter control. The gating signals effectively are provided by a shift register of an inverter control to the gates of the conduction controlled rectifying devices in the inverter in response to a clocking signal. The clocking signal is provided to the clock input of the shift register at a normal system rate when an idle condition (idle control signal) is not present and at a predetermined cycling rate from when the idle condition occurs until a desired fixed gating pattern effectively is provided by the shift register to the inverter. The shift register remains at the stage providing the desired fixed gating pattern until the idle condition no longer is present, whereupon the normal clocking signals are again provided to the shift register.

Abstract: An inverter controller for controlling a three-phase inverter used for generation and subsequent injection of pulse code signals on power lines in a utility load management system is disclosed. The controller includes read-only-memory devices (208, 210) for generating address bus information, read-only-memory devices (212, 214, 216) for generating gate control signals for inverter main valve SCRs, and read-only-memory devices (236, 238) for generating timing sequence control signals. The controller is responsive to microprocessor initiated control signals and features a state machine design.

Abstract: A triangle waveform having substantially linearly sloped, gradually increasing and decreasing edges and having a frequency nf is generated from an n-phase sine wave signal, each phase having a fundamental frequency f. A segment of any of the n-phases of the sine wave is detected when that segment is within a predetermined angular amount from a reference crossing level, such as the zero crossing of the sine wave signal. Successive ones of the detected segments are selected to synthesize the triangle waveform. In the preferred use of this invention, the triangle waveform is compared to a reference signal, such as the sine wave signal from which the triangle waveform is generated, this reference signal having a controllable frequency and amplitude. Pulse transitions are generated at the intersection of the triangle waveform and each of the respective phases of the reference signal.

Abstract: A frequency inverter using thyristor(s), wherein a gate circuit produces both positive triggering signals and negative reverse-bias signals by utilizing outputs of the timer in order not to fail turnings of the thyristor, and the timing of both signals are automatically controlled to by synchronized with oscillation of the resonance circuit connected to the anode and the cathode of the thyristor, so as to respond to a change of load condition, so that always suitable triggering signals and reverse-bias signals are applied to the gate of the thyristor.

Abstract: Converter apparatus including a power converter having controlled rectifier devices connected, and gated in a predetermined sequence, to interchange electrical power between a source of alternating potential and a direct current load circuit, a phase controller for controlling the conduction angle of the controlled rectifier devices, and circuitry for maintaining synchronous operation between the phase controller and the power converter. The circuitry for maintaining synchronous operation constrains the conduction angle between predetermined end stops by logically combining first and second logic signals developed for each controlled rectifier device from the source of alternating potential, with a logic signal associated with the immediately preceding controlled rectifier device in the gating sequence.

Abstract: A static power supply for converting DC power from a source to AC power at relatively high frequencies in a load. The static power supply is particularly useful for supplying power to induction heating loads operating at frequencies of 10 kHz. and higher. The DC supply is connected to supply substantially constant current to a controlled rectifier switching circuit. The controlled rectifiers are gated to produce alternating current in a commutating capacitor. The DC supply and switching circuit are connected to the load via a blocking capacitor so that the AC current component in the switching circuit appears as high frequency AC load current. The circuit arrangement imposes low operating stress levels on the controlled rectifiers, and provides a circuit turn-off time that is relatively independent of load.

Abstract: An induction heating apparatus having a heating unit with a plurality of parallel heater coils. A low-frequency a.c. power source provides the power which is converted by a static power converter into a high-frequency power applied to the heater coils to produce time-varying magnetic fields. The converter has a switching circuit connected in parallel with the heating unit and said power source for developing the high-frequency power with a frequency substantially equal to a frequency with which the switching circuit is triggered. Control circuitry provides a reference voltage generator and current detector for developing a voltage representative of the current flowing through the heater coils.

Abstract: An inverter system including a controlled direct current (d.c.) power source for providing a variable d.c. voltage to a variable output frequency inverter circuit by way of a suitable d.c. link, includes suitable circuitry for detecting a commutation fault or shoot-through condition within the inverter circuit and for taking appropriate remedial action to correct such condition. The shoot-through condition is determined as a function of the d.c. input current to the inverter circuit, the output alternating current (a.c.) of the inverter circuit and the extant condition of the load. In the particular embodiment of the invention illustrated, the load is an a.c. motor and the load condition sensed is whether the motor is in the running or idle mode of operation.

Abstract: The commutation circuit of an inverter is actuated only when the main thyristors cannot be transitioned to the nonconducting state by the removal of the gate signal. If a commutation pulse is required, the commutation capacitors are charged to the appropriate voltage level immediately prior to the switching point so that they may provide a sufficient pulse of current to extinguish the current through the thyristor. The commutation capacitors are then returned to a stable voltage level until another commutation pulse is required.

Abstract: Performance of an auxiliary impulse commutated inverter is significantly improved by controlling the interval between gating an inverter auxiliary thyristor into conduction for commutation of a then-conductive inverter main thyristor and subsequently gating an incoming inverter main thyristor into conduction as a function of inverter load current. When inverter commutation is commenced, a timing signal generator is actuated, producing a rising amplitude timing signal.A comparator continuously monitors the amplitude difference between the timing signal and a preselected inverter reference firing delay interval signal which varies in accordance with inverter load current. When the amplitude of the timing signal and inverter reference firing delay signal are equal, a bistable trigger resets the timing generator and causes the inverter incoming main thyristor to be gated into conduction, ending the commutation interval.

Abstract: Power control system comprising an intermittent device for applying intermittent voltage between intermittent voltage terminals; the intermittent device having a DC input terminal and at least one pair of intermittent terminals; a plurality of pairs of reverse series connected devices comprising control electrical valves and other electrical valves; said connected devices being connected in parallel between the intermittent voltage terminals; and a plurality of loads which are respectively connected to the series junctions of the plurality of pairs of reverse series connected devices.

Abstract: A DC-to-AC inverter includes first and second resonant circuit loops each including a capacitor, a primary coil of an output circuit, a silicon control rectifier providing a current path in one direction around the loop, and a conventional diode providing a current path in the opposite direction around the loop. A DC source is connected to supply a charging current through charging chokes to the capacitors in the resonant circuit loops. The silicon control rectifiers are periodically and alternately rendered conductive each to start a cycle of oscillation in one resonant circuit loops, while the DC source provides current to charge the capacitor in the other resonant circuit loop. The charging chokes and primary coils are phased to supply voltages which add to the voltage of the DC source during the charging of the capacitors.

Abstract: An inverter-cycloconverter power supply providing for the selective augmentation of the battery source (17) output voltage as needed to compensate for reductions in the effective voltage output of the latter source. The output tap points (for example, 48, 50) of the coupling transformer secondary winding (43) of the cycloconverter section (30) are selected to produce a pseudo-sine wave voltage (FIG. 2, 81) composed of alternating square wave voltages of a first and a second, higher level. A regulator section (60) including a second transformer secondary winding (63) controlled by a pair of thyristors (61, 62) adds a rectified voltage to the battery source (17) voltage as required as determined by regulator control circuitry. The latter comprises monitoring circuit means (83, 84, 85, 86, 87, 92, 95) for detecting the output voltage levels of the cycloconverter and for generating control signals (FIG. 2, 86) of a duration corresponding to the effective voltage drop of the battery source (17).

Abstract: The inverter comprises a plurality of branch circuits connected across a DC source. Each branch circuit includes a pair of main controlled semiconductor switching elements, a diode and a smoothing reactor which are connected between the pair of main controlled semiconductor switching elements. A commutating circuit including a commutating capacitor, a commutating reactor and an auxiliary reverse conduction type controlled semiconductor switching element is connected in parallel with each main controlled semiconductor switching element. A pair of circulating diodes are provided for each branch circuit and connected between respective commutating capacitors thereof and the positive and negative sides of the DC source.

Abstract: First and second resonant circuits store energy from a supply. First and second switches are respectively coupled to the first and second resonant circuits for generating resonant oscillations in the resonant circuits. A deflection circuit coupled to one of the resonant circuits has energy transferred to the deflection circuit during the resonant oscillations. A control circuit coupled to the switches varies the conduction angle overlap of the resonant oscillations in the resonant circuits for providing energy regulation.

Abstract: When a power conversion apparatus such as inverter or chopper comprises gate turn-off thyristors (GTO's), current limiting reactors are connected to cathodes of the GTO's and opposite ends of each of the reactors are connected to positive and negative terminals, respectively, of a gate power supply which supplies a turn-on current and a turn-off current to the respective GTO. With this arrangement, an energy stored in each of the reactors at the turn-off of the GTO is absorbed by the gate power supply.

Abstract: A supplemental or auxiliary portion of the commutation circuit for an inverter is actuated only during overload conditions which improve the inverter efficiency during normal load conditions. A control circuit responds to the increased time period of the commutation pulse to delay the firing of the thyristors which initiate the makeup pulse. This modified operation continues for at least three commutation cycles in order to ensure that the supplemental portion of the commutation circuit is properly initialized so that it is ready for subsequent overcurrent conditions.

Abstract: In a control apparatus for connecting three-phase current systems having respectively different frequencies to a high-voltage D.C.