Abstract: In a synchronous machine starting device, an AC voltage detection unit detects AC voltage supplied to an armature of a synchronous machine through an electric power line from a power conversion unit. The AC voltage detection unit has a first output end and a second output end isolated from the electric power line, transforms AC voltage supplied through the electric power line at a first ratio to output the transformed voltage from the first output end, and transforms AC voltage supplied through the electric power line at a second ratio and then limits the transformed voltage to a prescribed positive voltage value or lower and a prescribed negative voltage value or higher for output from the second output end. Then, a detected voltage selection unit selects one of the voltage received from the first output end and the voltage received from the second output end, and outputs the selected one to a rotor position detection unit.

Abstract: A control circuit, during a positive period in which current flows from a power conversion apparatus to a load, causes a second snubber capacitor to discharge by controlling a second auxiliary switch to be turned on while a second main diode is turned on, and during a negative period in which current flows from the load to the power conversion apparatus, causes a first snubber capacitor to discharge by controlling a first auxiliary switch to be turned on while a first main diode is turned on.

Abstract: A synchronous-machine starting device includes an electric power conversion unit for converting supplied electric power into AC power for supply to the armature of the synchronous machine, a rotor position detection unit for detecting a position of the rotor of the synchronous machine based on an AC voltage in the armature of the synchronous machine detected by an AC voltage detection unit, an electric power conversion control unit for controlling the electric power conversion unit based on the position of the rotor detected by the rotor position detection unit, and an abnormality detection unit detecting a rotation abnormality of the synchronous machine based on the AC voltage detected by the AC voltage detection unit after supply of the field current to the rotor of the synchronous machine is started.

Abstract: A power converter converts DC power supplied from a first DC power supply and a second DC power supply into AC power and supplies the AC power to a load. The power converter includes a protection circuit for allowing a charging current, which is possibly to flow from the first DC power supply and the second DC power supply to a first snubber capacitor or a second snubber capacitor, to flow to another current path, when a voltage applied to the first snubber capacitor becomes a predetermined value or more or when a voltage applied to the second snubber capacitor becomes a predetermined value or more.

Abstract: In a synchronous machine starting device, an AC voltage detection unit detects AC voltage supplied to an armature of a synchronous machine through an electric power line from a power conversion unit. The AC voltage detection unit has a first output end and a second output end isolated from the electric power line, transforms AC voltage supplied through the electric power line at a first ratio to output the transformed voltage from the first output end, and transforms AC voltage supplied through the electric power line at a second ratio and then limits the transformed voltage to a prescribed positive voltage value or lower and a prescribed negative voltage value or higher for output from the second output end. Then, a detected voltage selection unit selects one of the voltage received from the first output end and the voltage received from the second output end, and outputs the selected one to a rotor position detection unit.

Abstract: A synchronous-machine starting device includes an induction voltage operating unit (61) calculating an induction voltage induced to an armature of a synchronous machine based on an estimated phase representing a position of a rotor, an estimated rotational speed of a rotor, an AC voltage signal, and an AC current signal, and outputting an induction voltage signal representing the calculated induction voltage, a selection unit (SEL) selecting and outputting one of the induction voltage signal received from the induction voltage operating unit (61) and the AC voltage signal received from the AC voltage detection unit, and a feedback operating unit (34) calculating an error of the estimated phase based on the induction voltage signal or the AC voltage signal received from the selection unit (SEL), calculating the estimated phase and estimated rotational speed based on the calculated phase error, outputting a speed signal representing the calculated estimated rotational speed to the induction voltage operating un

Abstract: A synchronous machine starting device includes a power conversion unit for converting supplied power into AC power and supplying the AC power to an armature of a synchronous machine, an AC voltage detection unit for detecting AC voltage supplied to the armature of the synchronous machine, a rotor position detection unit for detecting a rotor position of the synchronous machine, based on the detected AC voltage, and a power conversion control unit for controlling the power conversion portion, based on the detected rotor position.

Abstract: A compensation control device for a power system includes a switched capacitor connected in series with a transmission line, a voltage applying control connected in series with the transmission line, and a ganged control for controlling on/off operation of the switched capacitor and a linearizing voltage generated by the voltage applying control. The control ensures that a sum voltage of a stepped voltage generated across the switched capacitor and the linearizing voltage produced by the voltage applying control and that is applied to the transmission line is continuous. The control device realizes controllability of the total impedance of the transmission line and reduces the capacitance of the parts employed in the ganged control.

Abstract: A power system compensator apparatus comprising a power converter unit that works in series with the transmission of a power system and switching control means for controlling the link voltage (V.sub.LINK) of the non-power system side. The switching control means controls the phase of, at least, the fundamental frequency of the power system. The power converter unit contains a static power converter transformer with phase differences taking place the secondary windings of the power converter unit. The static power converter unit is operated in non-PWM or fixed pulse width ratio. Switching rate is minimized. Loss is lowered while economy of operation is improved. Since the voltage that works in series with the power transmission line is controlled, direct compensation of system reactance voltage and direct control of line current are performed. Improved performance thus results.

Abstract: This invention relates to an apparatus for controlling a D.C. power transmission system having a line-commutated converter which is connected between a first A.C. system and D.C. power transmission lines and which performs power conversion between A.C. power and D.C. power, and a forced-commutated converter which is connected between the D.C. power transmission lines and having a second A.C. system and which performs power conversion between A.C. power and D.C. power. In order to control transmission power in the two-terminal D.C. power transmission system wherein the two A.C. systems are associated by direct current, a control apparatus for a D.C. power transmission system according to this invention includes a voltage detector which detects a D.C. voltage of the D.C.

Abstract: A control apparatus for thyristor motor comprises a voltage detector (27), a speed detecting circuit (600) and a correction circuit (800). The voltage detector (27) detects DC voltage (E.sub.d) supplied to an inverter circuit (200). The speed detecting circuit (600) detects the rotational speed of a synchronous motor (3) and provides speed voltage (E.omega.) proportional thereto. The correction circuit (800) detects a difference between the detected DC voltage (E.sub.d) and the speed voltage (E.omega.) and provides a correction signal to an excitation circuit (700) when a difference is detected. The excitation circuit (700) corrects field current in response to the correction signal so that the DC voltage (E.sub.d) and the speed voltage may be equal. Thus, a proportional relation can be maintained between the instructed torque and the generated torque.

Abstract: A gate pulse phase shifter is designed so as to generate pulses at intervals of 60.degree. regardless of distortions in the AC power supply voltage, and so that, for linearity in control, the phase reference signal and the DC output voltage of AC-DC converters connected to the device are proportionally related.

Abstract: The disclosed inverter system comprises three three-phase inverters connected in parallel across a positive and a negative terminal of a DC source including a negative terminal, and two three-phase transformers each including star-connected primary windings connected at one end to three AC outputs of the mating inverter and at the other ends connected to the neutral source terminal. Three secondary windings of each transformer are serially connected to those of the other transformer across three star-connected phase windings of a synchronous motor and three AC output of that inverter not connected to the transformer. The motor includes a neutral terminal connected to the neutral source terminal.