Abstract: The invention relates to static electric power conversion using semiconductors using soft switching in zero-voltage mode and controlled to perform pulse width modulation, having a first interface (L, C, T.sub.a, D.sub.a) in series between a DC voltage input (E) and a converter (1), and with a second interface (2) connected to the connection between the first interface and the converter (1) and organized, immediately before the end of a voltage window of amplitude (1+k)E to cause a positive current to flow through the switch (T.sub.a,D.sub.d) to counter the input current of the converter (1) which is negative when the ripple current flowing through the inductor is at its minimum value so as to reduce the current ripple amplitude required for switching off the switch (T.sub.a, D.sub.a), thereby reducing the current ripple for controlling interruption of the short circuit provided by the branch(es) of the converter (1).

Abstract: A converter circuit arrangement in which the gate turn-off thyristors are driven hard, i.e., the GTO is driven with a gate current configured in such a way that the turn-off gain IS/IGpeak is distinctly less than 3 so as to result in an anode voltage rise of at least 1 kV/.mu.s. The snubber circuit of such driven thyristors may be designed to include only a small number of elements. The voltage rise limiter includes at least one capacitor connected in parallel with one of the reverse-connected parallel diodes. The current rise limiter includes a parallel circuit having an inductor and a current limiting diode.

Abstract: The invention is an improvement of the PASC inverter, wherein the improvements include the reduction from two shorting gates per transformer to one shorting gate per transformer and replacement of active control of the shorting gate with passive control of the shorting gate. Further advantages are obtained through the use of anti-parallel gate sets.

Abstract: A power conversion device including a plurality of bridge connected self-turn-off modules. Each of the self-turn-off modules includes a plurality of self-turn-off devices connected in series and a plurality of first snubber circuits, each including a first series circuit of a first snubber capacitor and a first snubber diode. Each of the first snubber circuits is connected in parallel with one of the self-turn-off devices to form a first parallel circuit, respectively. The self-turn-off module further includes a snubber energy regenerating circuit including a regenerating transformer and a first auxiliary switch connected in series with a primary winding of the regenerating transformer. A secondary winding of the regenerating transformer is adapted for connecting to an outer power source. The self-turn-off module also includes a plurality of first gate circuits, each for driving one of the self-turn-off devices, respectively, and a second gate circuit for driving the first auxiliary switch.

Abstract: A converter circuit arrangement is specified which is constructed to have a particularly low inductance. This is achieved by the circuit area of the commutation circuit being kept as small as possible. A circuit area which is as small as possible is achieved by the branch modules and switch modules of a phase module being arranged either in a U-shape or in a meandering shape. The branch modules can be arranged either parallel to or at right angles to a main direction, between the positive and negative connections and the load connection. In addition, it is advantageous if the power semiconductor switches and the reverse-connected parallel diodes and freewheeling diodes are arranged in separate stacks which are held together by means of a clamping-in device.

Abstract: A voltage converter circuit uses a silicon-controlled rectifier for converting input voltage to selected levels of output voltage. The silicon-controlled rectifier is connected in a circuit including a capacitor which oscillates between charging and discharging to produce a resulting waveform that is applied to a transformer for developing high positive and negative output voltages. Pulses are produced which are asynchronous with alternating line signal. Since the silicon-controlled rectifier operates on DC voltages, an electrolytic capacitor of high capacitance values can be connected between the silicon-controlled rectifier and AC or DC supply lines to substantially reduce noise signals conducted back into the supply line.

Abstract: A high frequency power inverter comprises a power supply, a thyristor for switching the energy from the power supply to a load and a neutral capacitor for storing energy cyclically to assure reverse voltage is applied to the thyristor. A clamp circuit is associated with the switch to limit the ring-up voltage on the capacitor to a preselected value. The clamp circuit is comprised of an inductor having a relatively large value for permitting a gradual leaking of the capacitor voltage during an inverting of the power supply voltage to the load so that the capacitor can ring-up to a higher value than the supply voltage. The inductor is selected so that under all conditions, the voltage on the capacitor will be safely larger than the power supply voltage plus a load voltage peak for a time long enough to assure thyristor turn off.

Abstract: In one embodiment, an induction furnace is disclosed having a crucible, first and second set of induction coils surrounding the crucible and master and slave inverters, whereas in another embodiment, related to a channel-type induction furnace, the lower portion of the crucible houses at least first and second induction coils. The master and slave inverters each have a switching device with known turn-off-time characteristics for generating an alternating polarity output voltage across a load. The master inverter monitors the current, detects the zero-crossing of the current in the first induction coils, and generates a control signal in response to such detection of zero-crossing. The control signal is generated at an interval following the detection of the zero-crossing which is greater than the turn-off-time characteristic of the switching device.

Abstract: A switching arrangement for an RF-GTO is specified. It comprises a latching-type semiconductor component (GTO) of familiar construction. The circuit for turning off the semiconductor component (GTO) is designed in such a manner that the turn-off gain I.sub.A /I.sub.G, peak is distinctly less than 3 and, in particular, less than or equal to 1. During the turning-off, the drive is hard, that is to say has a high rate of increase dI.sub.G /dt and high current. A capacitance (C.sub.p) is connected directly in parallel with the semiconductor component (GTO).

Abstract: A pulse electric power unit according to this invention performs a switching control of output current from a direct current power supply by means of an electronically-operated switch to thereby effect a voltage conversion for producing a voltage having the polarity opposite to that of a direct current voltage by causing a direct current voltage of the direct current power supply to vary, or producing a voltage having the same polarity as that of the direct current voltage by boosting and/or unboosting the direct current voltage or producing a voltage having the same polarity as that of the direct current voltage by boosting the direct current voltage. This pulse electric power unit can prevent improper current from occurring by means of a reverse-current blocking diode for blocking a capacitor from being discharged and can output pulse current having a quick rise/fall characteristic.

Abstract: In a quarter-bridge circuit for high currents the total current is subdivided into a plurality of parallel current paths. In each current path a semiconductor component (5.1, . . . , 5.n, 6.1, . . . , 6.n) that can be turned off via a gate, a freewheeling diode (7.1, . . . , 7.n, 8.1, . . . , 8.n) located opposite a midpoint, and a clamping capacitor (9.1, . . . , 9.n, 10.1, . . . , 10.n) are arranged in parallel with the freewheeling diode (7.1, . . . 7.n, 8.1, . . . , 8.n) and the turnoff semiconductor component (9.1, . . . , 9.n, 10.1, . . . , 10.n) in such a way that the respective freewheeling path has as minimal an inductance as possible. Provided between a load terminal (3) of the quarter-bridge circuit and each midpoint of a current path is one inductor (L11.1, . . . , L11.n, L21., . . . , L21.n) each which limits the rate of current rise, so that a current rush caused by an operating delay does not overload the turnoff semiconductor component (9.1, . . . , 9.n, 10.1, . . . , 10.n).

Abstract: An electrical circuit receives an alternating input signal and full-wave rectifies the alternating input signal. The rectified signal is then developed by the circuit into an output signal which has a frequency double the frequency of the alternating input signal. The doubled-frequency output signal is then output to a load. Alternatively, the circuit receives a direct current input signal, converts the direct current input signal into a periodically varying output signal, and outputs the periodically varying output signal to a load.

Abstract: A power supply circuit for a high-frequency source (M) in a microwave oven includes a switched-mode-power-supply unit having a resonant circuit which contains a coil (L2) and a controllable switch (D1). The switching of the controllable switch is controlled by a control circuit (K) via a driving stage (S). The power supply circuit is cooled by a fan (F). The required DC voltages for supplying the driving stage, control circuit and fan are obtained by means of an auxiliary winding (W1, W2) on the coil (L2) and a rectifier (D3, D4). This results in a saving in both space and costs. At the same time, automatic supervision of the different functional units of the power supply circuit is obtained.

Abstract: In a DC power transmission system wherein two AC systems are interconnected by a first converter, a DC transmission line and a second converter to transmit power from one of the AC systems to the other of the AC systems via the DC transmission line, the DC power transmission system is provided wherein at least one of the first and second converters operating as an inverter is a current type self-commutated converter capable of being pulse-width controlled, the reactive power of the current type self-commutated converter is regulated by controlling a phase difference angle between its AC voltage and current, the DC voltage is regulated by pulse-width controlling the current type self-commutated converter, and the DC current is regulated by the converter operating as a rectifier.

Abstract: A turn-off control circuit for a gate turn-off thyristor is used in a state where one end of an inductive load is connected therewith on the cathode side. The turn-off control circuit includes a first turning-off transistor, which takes-out electric current through the gate at the first stage of the turn-off operation of the gate turn-off thyristor, and a second turning-off transistor, which takes-out electric current through the gate at the second stage of the turn-off operation of the gate turn-off thyristor so as to surely effect the turn-off operation.

Abstract: The PWM-controlled circuit includes an up/down counter and utilizes the fact that, when a numerical value is a complementary binary value, the sign is indicated by its most significant bit (sign bit). In the PWM control circuit, the up/down counter is controlled so that when its preset input receives a reference signal, a PWM signal of a duty factor proportional to the reference signal is directly obtained from the most significant bit of the output count.

Abstract: In a PWM inverter, a first three pulse mode, in which three voltage pulses exist within 120.degree. in the electric angle of the inverter output voltage, is changed over to a single pulse mode, in which the pulse width is equal to 120.degree., through a second three pulse mode, which is composed of two voltage pulses on both sides outside the period of 120.degree. and a center voltage pulse therebetween.The jump of the output voltage and the phase deviation therein upon changeover between the three pulse mode and the single pulse mode is prevented by controlling the pulse width of the two side pulses and the intervals between the center pulse and the side pulses.

Abstract: Circuit breakers which employ a capacitor to pass a current in opposition to a load current through a thyristor when interruption is required suffer from the disadvantage that high switching over-voltages occur. In the present invention current is diverted from the main first thyristor through a resistor when second and third thyristors are fired to pass a commutating current from a capacitor through the first thyristor. As a result the values of the resistor and the capacitor control the over-voltage and they are chosen to reduce it to approximately half the value obtained with equivalently rated conventional thyristor-based circuit breakers. In a second stage of commutation a fourth thyristor is fired to pass commutating current through the second thyristor to effect final interruption of the load current and the values of a parallel resistance-capacitance circuit in series with the second thyristor are chosen to reduce a second over-voltage which occurs when the second thyristor is commutated.

Abstract: In order to protect converter equipment which includes GTO switching-off thyristors and having d-c inputs and a protective inductance connected in series therewith against short circuit currents, a short circuit path for d-c current flowing from a d-c supply source on the one hand, and on the other hand, an energy storage device, is inserted into the d-c circuit, closed via an auxiliary thyristor, of the converter equipment in such a manner that through the change of the state of storage of the energy storage device, a countervoltage is impressed on the d-c terminals, which leads to the forcible commutation of the switching-off thyristors. The energy storage device advantageously comprises an auxiliary winding of a limiting choke serving as a protective inductance.

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: 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 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: The invention relates to a chopper circuit with free commutation for the supply of power to a load from a source of direct current. It comprises a principal thyristor with a return diode, a series resonant circuit as the commutation circuit and a free-wheeling diode. The free-wheeling diode is parallel to the capacitor of the resonant circuit so that the coil serves both as the commutation circuit and the coil to limit variations of the current in the thyristor. The circuit is particularly suitable for use with electric traction motors.

Abstract: A shunt switch comprised of a field-effect transistor (Q.sub.1) is employed to commutate a current-fed inverter (10) using thyristors (SCR1, SCR2) or bijunction transistors (Q.sub.2, Q.sub.3) in a full bridge (1, 2, 3, 4) or half bridge (5, 6) and transformer (T.sub.1) configuration. In the case of thyristors, a tapped inverter (12) is employed to couple the inverter to a dc source to back bias the thyristors during commutation. Alternatively, a commutation power supply (20) may be employed for that purpse. Diodes (D.sub.1, D.sub.2) in series with some voltage dropping element (resistor R.sub.12 or resistors R.sub.1, R.sub.2 or Zener diodes D.sub.4, D.sub.5) are connected in parallel with the thyristors in the half bridge and transformer configuration to assure sharing the back bias voltage. A clamp circuit comprised of a winding (18) negatively coupled to the inductor and a diode (D.sub.3) return stored energy from the inductor to the power supply for efficient operation with buck or boost mode.

Abstract: A power converter which converts alternating current (AC) utility power or direct current (DC) power to any DC output voltage by use of at least one switch and a resonant circuit resulting in power conversion by means of sinusoidal waveshapes. The resonant circuit defines the frequency of operation of the commutation circuit such that the frequency changes only a moderate amount with loads ranging anywhere from an open circuit to a short circuit, thereby providing reliable commutation and circuit operation under all load conditions.

Abstract: A power supply for electrostatic apparatus provides a high voltage output. The high voltage output is provided by the half wave rectification and filtering of a pulse signal from a secondary winding of a high voltage pulse transformer. The primary winding side of the high voltage pulse transformer is connected in a series loop circuit with a capacitor and a switching device. The capacitor is charged through an input choke connected to a DC supply source. The switching device is triggered after the capacitor is charged such that the capacitor is discharged through the primary winding of the high voltage transformer. The inductive collapse of the high voltage output transformer provides for the turnoff of the switching device and also serves to partially recharge the capacitor. The half wave rectified high voltage output of the power supply is obtained from the recovery pulse of the high voltage pulse transformer.

Abstract: An apparatus providing a source of alternating power for power devices is disclosed. The apparatus comprises a frame member having a plurality of ground engaging wheels for transporting the frame member along the ground. The frame member carries a plurality of DC storage means therein. A transformer means carried on the frame has a low voltage center tapped winding, a line voltage winding, and a high voltage winding. The low voltage center tapped winding is in communication with the DC storage means, and the line voltage winding is operable to produce an AC output voltage suitable for powering devices. A plurality of controllable rectifier means is in communication with both the high voltage winding and the low voltage center tapped winding. The rectifier means are operable to alternately provide a conduction path for said DC storage means through both halves of the low voltage center tapped winding.

Abstract: A regulator has a main valve connected between a first terminal of a d-c source and a first terminal of a load. A first series circuit poled similarly to the main valve and including a commutating valve in series with a commutating capacitor is connected in parallel with the main valve. Another series circuit including the commutating valve, a reversing valve and a reversing choke is connected in parallel with the main valve and conducts current in the same direction. A swingback valve is connected in parallel with the reversing valve and poled oppositely.

Abstract: An individual commutation for use with an inverter includes two resonant loops one of which is connected to the main current path adjacent each of the main thyristors. Each resonant loop includes a series coupled commutation capacitor and inductor together with commutation thyristor which is enabled to provide a commutation pulse to extinguish the load current through conducting main thyristor for a sufficient period to allow transition to the nonconducting state.

Abstract: A D-C voltage converter for controlling the voltage at an inductive load. The circuit is provided with a pulse transformer having first and second primary windings, a secondary winding, and a demagnetizing winding. The second primary winding receives a D-C voltage from a main D-C voltage supply by means of a controlled thyristor. The thyristor in combination with the first primary winding induce currents in the second primary winding and the secondary winding, which maintain a charge on a battery and which supply the inductive load. Electrical energy from the battery is used to produce a countervoltage for extinguishing a thyristor. In addition, circuitry is provided for extinguishing the conduction of the controlled thyristor.

Abstract: A circuit arrangement for the formation of periodic pulse patterns for use in controlling converters which is capable of quick change of circuit arrangement without time wasted in adjustment and capable of use in different applications without need to change circuit. The circuit arrangement of the invention is also useful for the formation of a periodic pulse pattern which is variable as a function of a control signal. For this purpose the desired pulse pattern is formed of auxiliary patterns stored in a number of memories. An oscillator drives a binary-coded counter which forms the addresses for a memory in which the desired pulse pattern is stored. The address inputs of at least one of these memories are connected to the output of the counter by means of an arrangement for address shifting which responds to a control signal.

Abstract: A digital control unit for a static converter contains a binary-coded counter which counts the pulses of an oscillator. The counter outputs are connected to the address inputs of a function memory in which sawtooth or ramp functions are stored. The numbers read out of the function memory are compared in a comparator, with a number determining the drive of the static converter. The result of the comparison and pulses on selected outputs of the counter are linked, in a logic circuit, to form firing pulses for the static converter. The invention is suitable for control units for static converters, in particular for AC control elements and inverters. All expense of adjusting, and all compensation of drift errors is obviated.

Abstract: A transient voltage suppression apparatus is disclosed for application in conjunction with a power supply line to protect the chopper thyristor in the transit vehicle propulsion motor control apparatus, wherein an electrolytic capacitor is provided to absorb the inductive stored energy of that power supply line in the zener mode of operation of that capacitor upon the occurrence of a system fault condition involving that power supply line.

Abstract: 1.

Abstract: A power converting apparatus and method comprising a transformer and converting circuit mounted with the transformer for converting direct current to a series of pulses in the primary winding which includes a pulse train forming an effective current with reciprocal positive and negative sine wave components for each half cycle of chosen frequency. A gating circuit is mounted with the transformer for sequentially passing the pulses in the positive sine wave components followed by the pulses in the negative sine wave component, the gating circuit passes the pulses received in the secondary winding synchronously with the pulses in each half cycle of the pulse train to form a chosen frequency alternating current component. A filter is mounted with the gating circuit for removing selected components of the received signal while providing an output of the chosen frequency alternating current.

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: 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 improved current supply apparatus for at least one load object capable of delivering reactive power. A DC current source is connected to at least two parallel circuit branches that each include a thyristor connected in series to a winding of an interphase transformer inductor. The ends of the load object are connected to an associated tap point intermediate the thyristor and inductor winding of each branch. The thyristors are successively ignited to conduct current during a portion of a current supply cycle to provide an output current of changing polarity to the load object.

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: A semiconductor circuit comprising a reactor including a closed magnetic path core of a compression molding which is formed of a mixture of an insulating material and particles of magnetic substance and a conductor magnetically interlinking to the core, and a semiconductor element connected in series with the reactor.

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: An induction heating apparatus includes a pair of thyristors inversely parallel connected to receive power from a low frequency energy source, a commutating circuit and a gating control circuit for supplying control pulses to the thyristors to produce a forward halfwave current through the commutating circuit which in return produces a backward commutating current to the thyristors. The gating control circuit includes a pulse transformer having a pair of secondary windings connected to the thyristors and a primary winding responsive to control pulses supplied from a pulse generator to produce a positive gating pulse in each of the secondary windings to drive one of the thyristors into conduction depending on the polarity of the source voltage to produce the forward current.

Abstract: An induction heating apparatus of the invention is provided with a pair of inversely parallel connected thyristors which receives power from a low frequency energy source. Depending on the polarity of the source voltage, one of the thyristors is triggered into conduction by a control pulse generated in delayed response to a sensed forward bias potential at its anode for the purpose of supplying a forward current to a commutating circuit which is tuned to a high frequency in the ultrasonic range, whereupon a backward current is generated. The backward current is commutated through the other thyristor to complete a high frequency oscillation. A detector is provided to detect when the magnitude of the backward commutating current reaches a predetermined value for the purpose of terminating the trigger control pulse.

Abstract: The proposed digital control device controls a d.c. thyristor-pulse converter and comprises a decoder connected to a clock pulse counter and a reversible counter. The device further includes a control unit, a matching unit containing four AND gates and a sign flip-flop, and a switching unit having six AND gates and two flip-flops. A first AND gate of the switching unit is connected to a control electrode of a first thyristor, a second AND gate of the switching unit is connected to a control electrode of a second thyristor, a third AND gate is connected to a control electrode of a third thyristor, a fourth AND gate is connected to control electrode of a fourth thyristor, a fifth AND gate is connected to the control electrodes of the first and third thyristors, and a sixth AND gate is connected to the control electrodes of the second and fourth thyristors. The clock pulse counter and the AND gates are connected to the flip-flops of the switching unit.

Abstract: An auxiliary commutation circuit to compensate for transient type overload conditions of an inverter comprises a pair of oppositely charged capacitors controlled by separate switches, each operable at a particular time during the conduction cycle of the main thyristors to provide additional stored energy for commutation during overcurrent conditions. A current detector senses the load current and provides a signal to an auxiliary gate whenever the rate of change in the load current or its absolute magnitude exceeds a preselected value. In response to the overcurrent signal and a timing signal, the auxiliary gate renders the appropriate switch operative coupling the charged auxiliary capacitor in parallel with the primary commutation capacitor so that the combined electrical energy stored on both capacitors is available for commutation. After the commutation period the auxiliary gate maintains the switch in its open state for a sufficient period of time to allow the auxiliary capacitor to be recharged.

Abstract: A power maximization circuit periodically samples the output power of a power supply to regulate output voltage or current toward that resulting in maximum output power. Power increasing variations in voltage or current are continued until maximum power is reached and exceeded, at which time the direction of variation is reversed until operation becomes stabilized at maximum power conditions. The circuit includes a sampling means for periodically sampling the output power. The sampling means is connected to a comparison means providing an output signal, the condition of which is indicative of whether the power at any given sampling period is greater or less than the previous sampling period. Means are provided for detecting on a coincidence basis, the condition of the comparison means output signal and for altering the magnitude of the current or voltage of the power supply toward that which obtains maximum power.

Abstract: The disclosure relates to an inverter comprising at least two controllable load thyristors. One diode each is connected in antiparallel fashion with each load thyristor, which diode is a component of a commutation installation for the corresponding load thyristor. The commutation installation manifests two LC-series oscillatory circuits, which are dimensioned for two different load currents. There is present for each LC-series oscillatory circuit one pair each of commutation thyristors. The two commutation thyristors of one of the two pairs, respectively, are alternately ignited such that, during the commutation of the load thyristors the commutation current can flow in a low impedance circuit.

Abstract: The disclosure relates to an inverter comprising at least two controllable load thyristors which connect a load alternately with the poles of a feed d.c. voltage source. There is connected in parallel with each load thyristor one diode each which is a component of a commutation installation. The commutation installation manifests an LC-series oscillatory circuit dimensioned for a specified load current, and, manifests, for each load thyristor a controllable commutation thyristor which forms a closed circuit with the LC-series oscillatory circuit and its diode. The LC-series oscillatory circuit is connected to an auxiliary d.c. voltage source of a constant voltage via a reloading circuit.

Abstract: A two-stage commutation circuit for an inverter, each having a different energy storage capability, commutates the main semiconductor switches by creating a commutation pulse suitable for the different levels of load current. This improves overall inverter efficiency by decreasing the circulating commutation current at light loads due to reduced size of the commutation and makeup pulses utilized at the lower load current levels. The control circuit for the dual commutation circuits includes a voltage detector for sensing the level of the DC input voltage and current detectors for sensing the times at which the load current is essentially zero so that the transistion between the commutation circuits will occur without perturbations in the cyclic operation of the inverter.