Abstract: A detecting apparatus for abnormality in an inverter circuit comprising an inverter circuit for converting electric power in a DC circuit into that in an AC circuit and vice versa based on a command signal for commutation, a detecting circuit for commutation in a main circuit, the detecting circuit being composed of a current detecting circuit provided between a voltage dividing point of the DC circuit and the inverter circuit and provided with its one end connected to the voltage dividing point and a differentiating circuit connected between the other end of the current detecting circuit and the AC terminal of the inverter circuit, and, a logic circuit for judgement of abnormality in commutation, the logic circuit comparing a detected signal of the detecting circuit for commutation in the main circuit with a command signal for commutation for commanding its commutation for the inverter circuit, and, at the same time, detecting inconsistency in logics of the detecting signal and command signal for commutation

Abstract: A fault detector for detecting faults in a DC capacitor circuit connected to the DC buses of an inverter circuit using semiconductor device for converting direct current into alternating current to suppress the voltage pulsation and comprising a plurality of parallel-connected capacitor circuits each having a plurality of series-connected DC capacitors. The fault detector comprises a comparison means connected to the junctions of the series-connected DC capacitors to compare the respective potentials of the parallel-connected capacitor circuits, and detects the short-circuit and time-aging of the DC capacitors of the parallel-connected capacitor circuits rapidly on the basis of the output signal of the comparison means.

Abstract: A circuit for storing energy delivered from an AC supply comprises a DC capacitor and a reversible chopper between an AC/DC reversible conversion circuit connected to the AC supply and a current supply circuit including a superconductive coil. This capacitor is connected intermittently to the superconductive coil in response to the action of the reversible chopper, so that when connected it delivers energy to the superconductive coil or receives energy therefrom. The reversible chopper circuit controls in accordance with required values the magnitude of transfer of energy between the DC capacitor and the superconductive coil.

Abstract: In a conversion system including a plurality of converter units connected to supply a.c. outputs to a load through a common bus, each converter unit includes a simulation bus circuit adapted to detect simulated lateral current between the converter units. Thus, testing of parallel operation control circuit can be executed easily, based on the simulated lateral current before paralleling the main circuit.

Abstract: In an inverter circuit composed of arms of at least one pair, connected between positive and negative lines of DC power source and turned on or off alternately, an abnormal state detecting circuit compares the neutral potential of the pair of arms with the neutral potential of the DC power source, and discriminates the abnormal state of the switching operation of the arms if the comparison result becomes less than a prescribed value.

Abstract: An apparatus for transmitting energy to and from superconductive coils, via a unipolar capacitor having a large capacitance. The apparatus is characterized by the use of two on-off self-controllable switches which are turned on and off under instructions from a control circuit or the like. The control circuits assure that the capacitor voltage remains constant by operating the switches in response to detected voltage levels.

Abstract: A circuit for transmitting energy to and from coils is improved by connecting a coil to a bridge circuit composed of a diode and a switch such as a gate turn-off thyristor. An opposite polarity switch and diode construction may be used in addition to selectively allow the direction of current flow through the coil to be reversible.

Abstract: A superconduction power storage apparatus includes a superconduction coil for storage and release of electrical energy, and a separately excited thyristor conversion unit having d.c. terminals connected to the said superconduction coil and a.c. terminals connected to an a.c. power source. The conversion unit is arranged so as to convert the electrical energy from a d.c. form to an a.c. form and vice versa between the superconduction coil and the a.c. power source. An on-load voltage regulator is connected between the a.c. side terminals of the thyristor conversion unit and the a.c. power source, and is arranged for adjusting the voltage appearing at the a.c. terminals of the thyristor conversion unit.