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 power transistor switch is disclosed which includes a transistor having an emitter, a collector and a base for ON-OFF switching, the transistor being connected in series to a path connecting a power source and a load. Means are provided for controlling reapplied voltage which is reapplied between the emitter and the collector of the transistor during the transition period when the transistor is switched to the OFF state to suppress the reapplied voltage at the time the collector current is substantially broken.

Abstract: An AC feeding apparatus which comprises a plurality of series solid state switch groups connected in parallel and with each series solid state switch group comprising N solid state switches connected in series. AC windings are provided for n(n.gtoreq.1) phase and m(m.gtoreq.2) independent groups of the windings are respectively connected to corresponding contacts of series connections of the solid state switches of the series switch groups. In the AC feeding apparatus, N solid state switches in each group and m groups of windings have the relation of 2m.gtoreq.N.gtoreq.(m+1) and at least two groups among m groups of the AC windings are excited with each phase difference of .DELTA..theta.(.noteq..pi.) in the turn-on control of the solid state switches. The AC feeding apparatus can be adapted for use in a rotating field generator, a commutator motor or an AC motor apparatus.

Abstract: A transistor switch device includes a main power transistor, an auxiliary solid-state switch, and an electricity replenishing means, wherein the electricity replenishing means is connected to the auxiliary solid-state switch which is connected between the collector and the base of the main power transistor so that the voltage drop at the collector of the main power transistor is reduced.

Abstract: An A.C. current control system for an A.C. power supply device for feeding a load comprises a closed control loop for controlling the power supply device on the basis of results of comparison between an output signal from a reference current waveform generator for generating a reference current waveform and an output signal from a load current waveform detector for detecting the waveform of load current. A load voltage detector is provided, the output signal from which is positively fed back to the closed control loop for compensating deviation in the current control due to electromotive force or like factors of the load.

Abstract: A semiconductor switch device includes a semiconductor switch with a control electrode disposed serially in a power path connecting a DC power source and a load; a current transformer having a core and having a primary conductor for passing current in response to a turn-on of the semiconductor switch and a secondary winding connected to the control electrode of the semiconductor switch; and a magnetizing force applicator for magnetizing the core of the current transformer in the direction opposite to the magnetization generated by current flowing in the primary conductor.

Abstract: A semiconductor switch comprising: a transistor; a thyristor connected between the collector and the base of the transistor; a first control device connected to the gate of the thyristor for supplying a gate current to the thyristor and thus turning on the thyristor; and a second control device connected to the base of the transistor for supplying a base current to the transistor and thus turning off the thyristor.

Abstract: An AC rotary machine apparatus comprises an AC rotary machine having AC windings forming five or seven phases and an AC feeder having solid state switches feeding AC power to the AC windings in five or seven phases.

Abstract: A motor drive apparatus has G groups (G.gtoreq.2) of m-phases inverter units and G groups (G.gtoreq.2) of m-phases AC windings for feeding through the m-phases inverter units to the m-phases AC windings and G groups (G.gtoreq.2) of DC power sources which are connected to G groups of the inverter units so as to form alternative series closed loops on the DC circuit.

Abstract: A power control or conversion apparatus comprises a combination of a controlled electric valve bridge and an electric valve bridge being coupled to each other in anti-parallel combination; DC reactors inserted in series in positive and negative electric paths coupling the controlled electric valve bridge with the electric valve bridge in anti-parallel combination; extension means for reverse-biasing the controlled electric valves of the controlled electric valve bridge to extinguish them; and switching means inserted in the coupling portion between the respective electric valve bridges and a DC power source. The extinction means and the DC reactors cooperate to forcibly commutate the controlled electric valve. The DC reactors also make current smooth.

Abstract: A current transformer for large currents having an inductive element, such as a large DC current transformer; a universal current transformer or a wide-band high fidelity current transformer, is improved by providing a shunt circuit which comprises a series connection of a first line comprising a first resistive element and a first inductive element and a second line comprising a series connection of a second resistive element, a second inductive element and the current transformer, wherein the first line is connected in parallel with the second line.

Abstract: A homopolar synchronous machine is disclosed which has a substantially lower inertia than equivalent conventional devices. The device includes components for forming a plurality of closed magnetic circuits along the axis of the stator, whereby the inertia is reduced and performance is improved.

Abstract: A system for driving an inductor type synchronous motor for minute control includes an inductor type synchronous motor having first means for driving m numbers of phases and a group of first magnetic teeth, second means equipped with a group of second magnetic teeth; and power feed equipment for feeding power to the driving windings of the individual phases; wherein the minute control characterized by the electrical resolution number R per electrical angle 2m (2m being one fundamental cycle) of the power feed equipment is larger than 3 m points (R.sub.2 3 m) or is stepless; and the power feed equipment feeds electric-waves of current or voltage to the driving windings, the electric-waves being trigonometric functional patterns formed by a control means of the power feed equipment.

Abstract: A system for controlling synchronous machines of the type comprising an ac winding, a dc excitation winding opposite to the ac winding across a gap, and a static switch connected to the ac winding is disclosed wherein a current variation is given to the dc excitation winding at commutation in the ac winding current.

Abstract: A chopper control device is disclosed, comprising: a series circuit having a dc power source, a dc load, and a thyristor; a transistor connected in parallel to the thyristor; a current transformer having a primary winding for detecting the load current; and another transistor for deriving a current from a secondary winding of the current transformer and supplying it to the base of the transistor.

Abstract: A thyristor turn-off system comprising: a thyristor having at least an anode, a cathode and a gate; a first reverse-bias means for applying reverse-bias between said anode and said cathode of the thyristor; a second reverse-bias means for applying reverse-bias to said gate of the thryistor; means for applying reverse-bias to said gate of the thyristor by said second reverse-bias means during the time of or before or after the forward bias initiation time for shifting between said anode and said cathode of the thyristor from reverse-bias to forward bias; whereby a failure of turn-off of the thyristor is prevented by said gate reverse-bias at least after said forward bias initiation time.

Abstract: A semiconductor switch comprising a transistor connected to a main circuit having a DC current and a load; pulsing means which is connected in series in an electric path connecting the collector and the emitter of the transistor; and a thyristor having main current electrodes connected in parallel to the series combination of the transistor and the pulsing means.

Abstract: A semiconductor switch device comprising: a main power source for supplying main current; a load connected to one side of said main power source; a semiconductor switch having first and second main current electrodes and a control electrode, the first main current electrode being connected to the other side of the main power source, the semiconductor switch being rendered conductive across the main current electrodes when a forward current is supplied to the control electrode; a current transformer having a core, a primary winding and a secondary winding, the primary winding being connected between the second main current electrode of the semiconductor switch and the load, and the secondary winding being connected at one end to the control electrode of the semiconductor switch, whereby a forward current responsive to the main current flowing in the primary winding is supplied from the secondary winding to the control electrode; and an auxiliary power supply connected between the other end of the secondary win

Abstract: A power converter comprising a plurality of pairs of electrical valve bridges which have a plurality of electrical valves connected in each bridge between DC terminals and AC terminals connected to an AC load and a plurality of controllable DC power means for feeding pulsating unidirectional current into the DC terminals of the electrical valve bridges or out of the DC terminals whereby the unidirectional pulsating current is distributed to the plurality of pairs of electrical valve bridges for feeding to the AC load. The power converter further comprises magnetically coupled reactors connected in unidirectional pulsating current lines. Alternatively, it further comprises DC lines of the unidirectional pulsating current lines which are connected as a common lines.

Abstract: A semiconductor switch device comprising: a semiconductor switch having at least one pair of control electrodes and at least one pair of main electrodes, the control electrodes being supplied with a control current while the semiconductor switch is maintained conductive between said main electrodes, and the main electrodes being serially inserted in a current path; and a transformer having a first conductor responding to a current passing said current path, a second winding connected to said control electrodes, a third winding producing a magnetomotive force reverse to that produced across said first conductor, and a fourth winding producing a control current to said control electrodes by induction from said third winding, the third winding being equipped with an electrical pulse applying means capable of causing said third winding to produce said reverse magnetomotive force.