Abstract: A converter circuit includes three-phase unit converters connected in cascade in two stages for supplying electric power to a load. In a region in which the converter output voltage ratio is small, the firing phases of both converters are so set that a phase difference of 120.degree. makes appearance therebetween, while in a region in which the converter output voltage ratio is large, the firing phases are so set as to have a phase difference of 60.degree. therebetween, whereby an angular difference of 90.degree. to 30.degree. is caused to occur constantly between the phases of voltage ripple components of the unit converters. Power factor of a power supply source is improved while ripple in the output voltage of the converter circuit is reduced.

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: A circuit for the linear measurement of a current flowing through a load which comprises a current sensor consisting of a resistor, and a first driver transistor connected to the load and a second transistor connected to the resistor, both transistors being field effect transistors interconnected into a current mirror configuration, which includes an operational amplifier having its inputs respectively connected to the drain electrodes of the first and second transistors to regulate the drain-source voltage of the transistors and enable linear measurement of the load current irrespective of the operating temperature.

Abstract: A transformer-coupled two-inductor buck converter is provided which comprises a series input circuit including an input inductor, a capacitor and a grounded inductor. The input and grounded inductors are wound so that a source of d.c. input voltage can be connected across positive polarity outer ends thereof. A transformer is provided for coupled the input and output circuits of the converter. When a switching transistor in the input circuit turns on, input current conducting through the input inductor joins with current being dragged out of the grounded inductor and through the capacitor to conduct through the primary winding of the transformer and couple to the secondary winding for delivery as output current to the load. An output winding coupled to the grounded inductor is connected by a switching diode to the load.

Abstract: A pulse absorbing circuit is disclosed for a power source circuit for absorbing an abnormal pulse when an input current at a primary winding of an output transformer in a switching power source is cut off. The pulse absorbing circuit includes a capacitor, one end of which is connected to a secondary winding output terminal of a transformer in a phase opposite to a primary winding input terminal thereof. A first rectifying element is provided, an anode of which is connected to the other end of the capacitor and a cathode of which is connected to an output terminal of a rectifying circuit arranged at a secondary winding side of the transformer. A second rectifying element is provided, a cathode of which is connected to a junction between the first rectifying element and the capacitor. A conductor is inserted between a ground terminal and the second rectifying element. The conductor has, for example, a coil for absorbing and effectively reutilizing abnormal pulse energy.

Abstract: Method and Apparatus for resumption of normal operation of a High Voltage Direct Current transmission line after a malfunction in one of two stations connected to a HVDC transmission line. A control angle of approximately 90 degrees is run up in the previously malfunctioning station in accordance with a given function, thus creating an indication quantity at the D.C. voltage connections of the other station, which is detected as the earliest possible information on the start of the external station and also enables the run-up of the control angle in accordance with a given run-up function, with the two run-up functions representing precalculated, compatible, actual substitute values for the fault indication quantity caused by the respective other station. At the end of the run-up, the run-up functions are switched over to measured values of fault indication quantities, thus attaining stable control with short run-up and control times.

Abstract: A method and apparatus are described for operating a high voltage d.c. (HVDC) transmission line system connecting two a.c. transmission line systems during normal operation and during malfunction in either the rectifier station or the inverter station of the HVDC system.When a malfunction exists in one station of a HVDC transmission line, such as a rectifier station, then the regular thyristor firings are disabled and a bypass circuit, preferrably one or several bridge paths of a converter, are fired. As soon as a corresponding change in the current or voltage occurs at the d.c. voltage connections of the other station, this station assumes rectifier operation during which the HVDC transmission line is utilized as a reactive load to stabilize the other system. Once the malfunction has ceased to exist, operation is first resumed in the first station by extinguishing the bypass thyristors and subsequently resumed also in the other station.

Abstract: A remotely controlled circuit control device has first and second load contact assemblies movable into circuit engagement and circuit disengagement positions relative to one another in which one load contact assembly is operatively connected to a solenoid so that alternate forward strokes of the solenoid moves the one load contact assembly between reset and tripped positions through a push-push mechanism having an indexing portion and a latching portion. An overload mechanism cooperates with the latch portion to cause the load contact assemblies to move to the circuit disengaged position upon occurrence of a fault condition. The second load contact assembly includes pivotably mounted contact members which are linked to the first load contact assembly in such a way that circuit engagement during solenoid energization is precluded.