Abstract: An inverter circuit includes fast transistors for PWM and slow switching thyristors for a fundamental frequency. The inverter circuit further includes a rectifying circuit for rectifying an input AC power and a bridge circuit. The bridge circuit includes a plurality of bridge circuit arms, each of the bridge circuit arms constituted by connecting a collector terminal of a transistor to a cathode terminal of a thyristor. An emitter of the transistor is connected to a negative side of the rectified output of the rectifying circuit, and an anode of the thyristor is connected to a positive side of the rectified output of the rectifying circuit.

Abstract: The invention relates to a converter which can operate as a rectifier to rectify alternating current into direct current running in one direction (for example to charge batteries) or a converter where DC (from the batteries) can be converted to AC and supplement AC power, for example to supplement an alternator output in peak load conditions. The converter comprises a uni-directional electrical energy source (battery) and a bi-directional energy source (small battery bank connected for reverse direction current flow, capacitor or fuel cell) which is capable of initiating an alternating current when controlled by thyristors fired in sequence and with such periods that a sine wave can be simulated. The switches are controlled by a thyristor trigger logic current control unit which may for example be a micro processor.

Abstract: A method of operating a three-step inverter that supplies a polyphase machine whose electric output variables are formed by scanning two zero-shifted setpoint signal sets with triangular modulation signal, in a space vector representation using double modulation. A first or second interval value is formed between the maximum or minimum value of phase signal waveforms of the setpoint signal sets and an upper or lower scanning limit. The first and second interval values are added or subtracted from the phase signal waveforms of the first and second setpoint signal sets, to thereby increase the linear control range of the inverter and reduce the harmonic spectrum in the inverter output signals.

Abstract: A high efficiency power converter is achieved which eliminates the needs for self-commutated devices and requires only twelve thyristors for full double bridge AC/AC power conversion. The system utilizes a series resonant DC link between the AC/DC and DC/AC converters. The DC resonant circuit functions as a commutating circuit which ensures turn off of all twelve thyristors by providing the necessary zero current instants. A significantly improved sinusoidal current waveform can be obtained on both the input and the output compared to conventional high power converters by the use of high frequency pulse density modulation.

Abstract: A series resonant power supply is switched at a constant frequency above the audio range, in which a magnetic amplifier is used to control the magnitude of the output voltage. It can be run silently, while providing high power at relatively low cost. The power supply includes a full or half bridge rectifying circuit with first and second common terminals. A magnetic amplifier is coupled from the first common terminal to a second common terminal. The magnetic amplifier includes a first primary coil for conducting current from the first common terminal to the second terminal. A secondary coil for generating an output current, and a control coil receiving a control current are coupled with the first primary coil. A second primary coil is connected to conduct current from the second common terminal to the first common terminal. A second secondary coil and a second control coil are coupled with the second primary coil.

Abstract: The invention relates to a parallel oscillatory circuit frequency converter comprising: a rectifier (1); an inverse rectifier (4) having thyristors disposed in a bridge circuit; a parallel oscillatory circuit (5) having an inductance (L) and a series connection of two capacitors (C, C.sub.K) whereby one capacitor (C) is connected to the load points of the bridge circuit; and a gate-controlled turn-off time control device (6) for the alternate firing (switching) of the thyristors a, b forming the particular diagonally adjacent bridge branches with a cycle frequency adapted to maintain a minimum turn-off time, a safety firing circuit (24, 25) controlled by a detector circuit (11-23) to detect incorrect switching delivering firing pulses without delay to all the thyristors at least until all the thyristors are current-carrying.

Abstract: Low-loss external wiring, for the switching-off relief of the semiconductor switching elements in a stage of a three-level inverter provides a switching-off relief capacitor which is connected to the stage output. Wiring capacitors are coupled to each of the upper and lower ends of the stage. The inverter also includes a diode network. Additional d-c consumers which are preferably either ohmic resistors or energy recovery devices take up energy which is interim-stored in the wiring capacitors.

Abstract: In an inverter supplied with power from a DC power supply whose voltage rises at a light load operation, if an overcurrent failure occurs at a light load operation at the inverter output side as seen from the DC power supply, a surge voltage higher than a voltage withstanding of the switching elements of the inverter is generated across the elements, the surge voltage being higher by the amount corresponding to a rise in the DC power supply voltage. Therefore, there arises a possibility of breaking the switching elements. This inconvenience can be solved by lowering the overcurrent detection level by the amount corresponding to a rise in the DC voltage, when a light load operation as seen from the DC power supply side is performed.

Abstract: A high voltage power supply circuit for a high frequency medical X-ray generator comprises a high voltage transformer having a primary and a secondary and an inverter circuit responsive to predetermined control input signals for producing corresponding inverter output signals. A responant circuit is coupled with the inverter circuit and is resonsive to the inverter output signals for producing corresponding voltage pulses for energizing the primary of the high voltage transformer. The resonant circuit includes a capacitive component and an inductive component, the latter being provided by the primary of the high voltage transformer coupled in series circuit with the inverter circuit and with the capacitive component. A KVP regulator circuit provides the control input signals for the inverter circuit in the form of a series of KV firing pulses.

Abstract: Active snubber structure and method for use with an electronic power inverter to reduce turn off losses in electronic switches in the power inverter. The snubber structure includes a resistor and a capacitor connected in series with each other and in parallel with the load on the power inverter and parallel, inverse connected silicon controlled rectifiers connected in parallel with the resistor for selectively shorting the resistor.

Abstract: In a control apparatus for a power converter for controlling a power converter on the basis of stored values of a memory adapted to store variables over a fixed time period of the power converter while sequentially updating them, when an abnormal state occurs in the power converter, writing into the memory is stopped to effect a control using data having been stored immediately before that abnormal state occurs, thus to restart writing into the memory at the time when that abnormal state is removed.

Abstract: An inverter system having two resonating current sources which are resonant at the same frequency. The currents of the two sources are combined. At low power levels, the currents are substantially out of phase and the frequency is adjusted. At intermediate power levels, the currents are adjusted in phase and the frequency is fixed. At high power levels, the currents are substantially in phase and the frequency is adjusted.

Abstract: An inverter having an output connected to a load through a reactor and an output filter capacitor terminal voltage of the capacitor is monitored, and an interlock operation for interrupting the delivery of the inverter transistor drive signals is released when the terminal voltage does not exceed a predetermined level. When the interlock operation for cutting off the drive signals of the transistors has started and continued for a predetermined time, it is further continued when the terminal voltage of the output filter capacitor does not drop below a set level and is released for the first time when the output filter capacitor is sufficiently discharged to render the terminal voltage the set level or below.

Abstract: The present invention provides an optically controlled power converting apparatus using light trigger/light quench electrostatic induction thyristors, as switching elements, which can execute the switching operations at a high speed being when they are supplied with light trigger pulses and light quench pulses. By supplying the light trigger pulses and light quench pulses at the timings corresponding to the pulse width modulation, the light trigger/light quench electrostatic induction thyristors can perform predetermined power converting operations.

Abstract: A versatile pulsed voltage resonant inverter power supply for an ozonator which results in the efficient operation thereof. A resonant inverter ozonator power supply comprises a DC power source and a DC/AC thyristor inverter coupled at its outputs to the primary winding of a high voltage transformer. The ozonator load is connected across the secondary winding of transformer and provides a discharge path during each high frequency cycle. First and second embodiments of control circuits are disclosed for generating gating control signals for the thyristors. The switching frequency at which the thyristors are triggered is selected to be lower than the circuit resonant frequency in order that the load voltage supplied by the inverter is substantially pulsed, and a pulse burst modulation mode is also disclosed.

Abstract: The invention relates to a phase-adjusting device for the inverter, having controllable semiconductors, of a parallel-resonant circuit frequency converter. The phase-adjusting device, operating on the PLL principle, compares a signal derived from the inverter output voltage and a signal delayed by a predetermined amount in relation to the control pulses of the oscillator 1 to a phase-comparing stage. In dependence on the phase comparison of the two signals, the oscillator frequency is so adjusted that the inverter output voltage and the inverter output current are in phase.

Abstract: The invention concerns a converter (2) provided with GTO thyristors the frequency and characteristic shape of its output voltage (U.sub.A) being constrained by a load (3). The frequency of the converter (2) is matched to the constrained output voltage (U.sub.A) with the aid of a regulating circuit (4). Non-simultaneously switched GTO thyristors are switched on and off in a predetermined timed relation to each other (FIG. 3).

Abstract: A resonance inverter includes a DC power source, a resonance capacitor, an inductor, and a plurality of semiconductor switches. The resonance capacitor and inductor form a parallel resonant circuit. The inverter further includes control means for detecting a peak value of the voltage across the resonance capacitor, and for alternately conducting said semiconductor switches with a certain lead phase with respect to the peak point of the capacitor terminal voltage.

Abstract: A versatile pulsed voltage resonant inverter power supply for an ozonator which results in the efficient operation thereof. A resonant inverter ozonator power supply comprises a DC power source and a DC/AC thyristor inverter coupled at its outputs to the primary winding of a high voltage transformer. The ozonator load is connected across the secondary winding of transformer and provides a discharge path during each high frequency cycle. First and second embodiments of control circuits are disclosed for generating gating control signals for the thyristors. The switching frequency at which the thyristors are triggered is selected to be lower than the circuit resonant frequency in order that the load voltage supplied by the inverter is substantially pulsed, and a pulse burst modulation mode is also disclosed.

Abstract: A power converter including a plurality of serially connected self-turn-off semiconductor elements, including a first control circuit for producing a plurality of control signals, and a plurality of second control circuits is connected to receive respective of the control signals to supply a non-conduction control signal to a respective of the self-turn-off semiconductor elements to turn off the respective semiconductor element. The power converter further includes a plurality of failure detectors and blocking circuits. Each of the failure detectors is connected to a respective of the self-turn-off semiconductor elements for detecting a fault thereof to produce a fault detection signal when the respective self-turn-off semiconductor elements has failed. Each of the blocking circuits is connected to the respective failure detector and to the first control circuit for blocking either the respective control signal or the respective non-conduction control signal based on the respective fault detection signal.

Abstract: An inverter using gate turn-off thyristors (GTOs) is controlled by means of pulse width modulation (PWM) to control the speed of an induction motor. If the current flowing through the induction motor becomes an overcurrent which can still be cut off by the GTOs, a gate off signal is supplied to respective GTOs to interrupt the overcurrent. If any one of arms respectively corresponding to phases is short-circuited, a gate on signal is supplied to all GTOs to distribute the short circuit current among the arms, and the main circuit is interrupted by a high-speed breaker. At this time, a simultaneous gate on signal is given priority. If the simultaneous gate on signal is present, a simultaneous gate off signal is disabled. Owing to this configuration, destruction of the GTOs due to consecutive guard operation can be prevented.

Abstract: A DC-AC converter comprises a bridge of electronic switches having a load connected in one diagonal and the constant voltage source connected to the other diagonal. The two switches of each bridge branch are connected to one another by at least one resistor, the load being connected to one end of the resistor.

Abstract: According to the invention, the system comprises a resonance type inverter, a diode rectifier bridge and single regulation loop controlling controlled switching means, forming a chopper, interconnected between the rectifier bridge and the inverter. The system is applied to X-ray equipment.

Abstract: Transistors or GTO's of an inverter are switched ON/OFF with a delay circuit which has a capacitor first charged at a forcing rate, then, held at an intermediary level, and which is first discharged at a forcing rate, then held at an intermediary level, thereby to provide underlap, minimum ON and OFF time control and noise filtering with a high precision.

Abstract: A power conversion device such as an inverter using as bridge arm elements self-extinguishing-type switching elements for converting D-C input power into A-C load power. Snubbers, each including a capacitor and a diode in series, are connected in parallel with the switching elements. A discharging circuit, having a diode is connected across the diodes of the snubbers, and a power source feedback circuit, including a current transformer, are employed to return the current discharged from the snubbers to the input power source, thereby enhancing conversion efficiency.

Abstract: A two-pole inverter bridge has an inductor mounted between the two controlled switches in each pole and a resonant load is connected across the poles between ends of the inductors which are similarly situated relative to the terminals. In each pole one antiparallel circuit includes an auxiliary controlled switch and another antiparallel circuit includes only a diode. Fault protection is provided with an auxiliary source mounted between opposite ends of the inductors for applying reverse bias to the controlled switches of the poles whenever a fault in the inverter is detected.

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 nondissipative current distribution circuit for a power source, such as magnetohydrodynamic generator, that delivers its output current through a first plurality of positive electrodes and a second plurality of negative electrodes (including plural positive and negative electrode pairs) and provides a predetermined current distribution among the electrodes, is described, and comprises a transformer including first and second windings, the second winding including means for connection to a load, the first winding having plural adjustable taps intermediate its ends, an inductor connected at one end to one end of the first transformer winding and at the other end to a plurality of capacitors connected respectively to each electrode, and a first plurality of silicon controlled rectifiers connected, respectively, between each positive electrode and a tap or the second end of the first transformer winding, and a second plurality of silicon controlled rectifiers connected, respectively, between each negative elect

Abstract: The invention relates to an electrical safety device controlled by mutually independently generated pulse trains (i.sub.a1, i.sub.b1) for providing alternating current (i.sub.L1) through a winding (L1) only as long as the pulses in the pulse trains occur alternatingly and the components in the safety device are not faulty. The safety device in accordance with the invention includes at least one pair of switching devices (T1, T2) provided with control electrodes (a1, b1) each adapted for receiving a pulse train for alternatingly making the switching devices (T1, T2) conductive and non-conductive.

Abstract: An equalizer circuit for switches connected in series between a voltage source (21) and a load (16), each switch (4, 11) being connected in parallel with a respective equalizing capacitor (2, 9) via a respective diode (7, 8). The circuit further includes a transformer (20) having a plurality of windings (6, 13) connected in series with respective diodes (5, 12), with each switch having a respective winding-diode series connection connected in parallel therewith. In this manner, electrical energy initially stored in the capacitors is transferred to be stored in magnetic form by the windings when the switches are closed and is re-used when the switches are opened to accelerate charging of the less charged capacitors until all the capacitors reach the voltage of the most charged capacitor.

Abstract: An inverter circuit with a thyristor bridge circuit, a load circuit developed as a parallel oscillating circuit connected to the bridge circuit, an impulse generating circuit for supplying ignition pulses to the bridge circuit and an arcing time regulating circuit for controlling the impulse generating circuit in accordance with the arcing time. A down-and-up integrating circuit is triggered by an ignition impulse to integrate down until a discriminator circuit produces a signal indicating zero crossover of the load current, thereafter to integrate up until a second discriminator produces a second signal indicating zero crossover of the load voltage, at which time the integrator output indicates arcing time, and is applied to the time regulating circuit to control the impulse generating circuit.

Abstract: A method of and apparatus for controlling an inverter of a load commutation type, the inverter having arms each having a thyristor in which pulses are produced and distributed to the gates of the thyristors for performing, under normal circumstances, constant margin time control or constant margin angle control. The voltage across the load is detected and its magnitude is compared with a predetermined level. When the magnitude exceeds the predetermined level, a pulse is produced and delivered through the distributor to the gates of the thyristors.

Abstract: A control circuit for a power converter which converts between polyphase periodic power and unidirectional power is disclosed. The control circuit includes first means for sensing a parameter of the periodic power and a ramp generator coupled to the first means for generating a ramp signal having a frequency equal to the frequency of the periodic power. A second means senses a parameter representative of a condition at the output of the power converter and a comparator combines the outputs from the ramp generator and the second means to generate a pulse train having a frequency equal to the frequency of the periodic power but shifted in time relative thereto, with the shift being dependent upon the output parameter. A phase-locked loop, of PLL, multiplies the frequency of the pulse train and additionally develops a signal which is coupled to the ramp generator to maintain the amplitude of the output therefrom at a constant level irrespective of changes in frequency of the periodic power.

Abstract: This line-commutated converter, in one form, has a pair of D.C. terminals for connection to a D.C. system and a pair of A.C. terminals for connection to an A.C. system. The converter comprises first, second, third, and fourth branches, each comprising the combination of a thyristor and a diode connected in inverse-parallel and an inductor connected in series with this combination. The first and fourth branches with a first node located therebetween are connected in series across the D.C. terminals; and the second and third branches with a second node located therebetween are also connected in series across the D.C. terminals. The nodes are effectively connected across the A.C. terminals. Controlled gating means simultaneously triggers the first and second branches into conduction at a controlled phase angle with respect to the A.C. system voltage and simultaneously triggers the third and fourth branches into conduction 180 degrees thereafter, repeating this sequence each cycle of the A.C. system voltage.

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 inverter bridge provided with a series-network in its diagonal including an inductor and an output transformer is feedback-controlled to generate a sine wave by reference to a sine wave reference signal and in a self-oscillatory fashion of the "bang-hang" type. The series-network operates during the "hang" phase as an active filter. Transistors are used on the high frequency side of the bridge and thyristors are used on the fundamental frequency side of the bridge. Provision is made for an AC source in parallel with the load, in which case feedback control is in response to the relative shares of the sources in the common load.

Abstract: The hybrid inverter consists of thyristor switches with their related commutation circuit, paralleled by transistor switches. When the current magnitude is below a predetermined level, it is conducted by the transistor switches and when above the predetermined level, it is conducted by the thyristor switches. The commutation circuit includes a capacitor which need not be precharged to initiate commutation. Thus, the commutation circuit works only when a thyristor is conducting current thereby substantially reducing the number of commutations in an output cycle.

Abstract: A hybrid phase-controlled rectifying bridge includes both controlled and uncontrolled electric valves referred to as thyristors and diodes, respectively. Each of a pair of thyristors is periodically fired at an "angle" that can be advanced or retarded as desired, whereupon load current commutates to the thyristor from the corresponding diode. Subsequently the thyristor is turned off at a desired extinction angle by the action of cyclically operative forced commutation means. To avoid reverse recovery overvoltages across a diode when the desired extinction angle is only slightly larger than the firing angle, means is provided for temporarily preventing any turnoff action during the diode-to-thyristor commutation interval and for an additional interval that gives the diode sufficient time to fully recover its reverse blocking capability.

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 that has an AC link includes an input current type inverter and an output voltage type inverter coupled together by a transformer. The negative terminal of the current type inverter is connected in series with the positive terminal of the voltage type inverter. Controlled rectifiers are used in the current type and voltage type inverters and the angle, relative to a fixed point in the AC cycle, at which the controlled rectifiers are turned on and off is varied to obtain desired converter action. A substantially smaller transformer, thus, is required.

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 transistor is operated in the PWM mode such that a hlaf sine wave of current is delivered first to one-half of a distribution transformer and then the other as determined by steering thyristors operated at the fundamental sinusoidal frequency. Power to the transistor is supplied by a dc source such as a solar array and the power is converted such that a sinusoidal current is injected into a utility at near unity power factor.

Abstract: A resonant circuit inverter has an LC series resonant circuit and a switching device for connecting the resonant circuit with periodically alternating polarity to a dc voltage source, the switching device feeding a high voltage transformer. The resonant circuit inverter further includes an interstage transformer having a primary winding serving as the inductance in the LC resonant circuit and having a secondary winding connected to the primary winding of the high voltage transformer, the high voltage transformer having a secondary winding at which the load voltage is tapped.

Abstract: An improved D-C to A-C inverter circuit is provided including push-pull sequentially activated thyristor switches connected across a center-tapped D-C voltage source with a saturable reactor connected in series between each thyristor and the center-tap return branch and at least one saturable reactor connected in the center-tap return branch to effectively reduce peak operating voltages.

Abstract: The commutation circuit for commutating a conducting thyristor includes an inductance, a capacitance and a commutation thyristor all connected in series with the conducting thyristor and the dc source, the commutation thyristor initiates the commutation when triggered. The circuit further includes a first diode connected in reverse polarity across the commutation thyristor and a second diode connected in reverse polarity across the commutation thyristor-capacitance series circuit. The voltage across the capacitance is zero when each commutation cycle is initiated, and also when each commutation cycle ends.

Abstract: 1.

Abstract: A self-commutated inverter has two alternately conducting main branches which, in series with each other, are connected to a d.c. voltage source. The point of connection of the main branches constitutes the phase terminal of the inverter and a turn-off circuit is connected to this connection point. Each main branch includes a commutating inductor at least one of which is provided with an auxiliary winding. The auxiliary winding is connected in series with diodes means and this series connection is connected to the d.c. voltage source for feedback of surplus energy in a commutating circuit and symmetrization of commutating capacitor voltage.

Abstract: An a.c. operated arc welding current supply unit comprises a frequency converter of the series capacitor type and operating with a half period which is substantially less than the average duration of the current and voltage transients caused by short circuits through droplets of weld material during welding. The frequency converter is connected to welding electrodes through a transformer in series with a rectifier to provide direct current for the welding electrodes, and the frequency converter is associated with a control device for maintaining the operating frequency of the converter constant, thereby maintaining the arc power substantially unchanged irrespective of changes in load caused by the welding operation.

Abstract: The inverter may be single phase with one inverter leg or N-phase with N inverter legs for connection across a DC source. Each leg includes a pair of series connected thyristors with a terminal between the thyristors for connection to a load. In addition, each thyristor has a diode connected in reverse polarity across it. A commutation circuit which includes an inductor in series with the inverter legs and a capacitor in parallel with the inductor and the inverter legs, provides a commutation pulse to turn off the thyristors in each leg. A further isolating inductor is connected at the DC power input to the inverter, and a reverse polarity feedback diode may be connected across it.