Abstract:
PROBLEM TO BE SOLVED: To protect a converter circuit when an asymmetric phase voltage occurs in an AC voltage network connected to the converter circuit. SOLUTION: The converter circuit has a converter unit 1, equipped with a plurality of controllable power semiconductor switches, and the converter unit 1 is connected on an AC-voltage side, to an AC-voltage network 2 and is controlled by a control signal S. For protecting the converter circuit, when an asymmetric phase voltage occurs in the AC-voltage network connected to the converter circuit, phase voltages (U Na , U Nb , U Nc ) in the AC-voltage network are calculated. Negative sequence strength of the phase voltage is calculated, and Park and Clark transformation strength of phase voltage is calculated; and when the negative sequence strength of the phase voltage exceeds a value that can be set; or if the Park and Clark transformation strength of the phase voltage drops beyond the value that can be set, the controllable power semiconductor switch will be locked by a control signal. COPYRIGHT: (C)2008,JPO&INPIT
Abstract:
PROBLEM TO BE SOLVED: To provide an arc furnace power supply device in which stable and uniform arcs can be secured. SOLUTION: The arc furnace power supply device includes a commutator (1) which can be connected with an AC voltage supply network (2) on its AC voltage side and connected with a DC voltage circuit (3) on its DC voltage side. Furthermore, the arc furnace power supply device has an inverter (4) which is connected with the DC voltage circuit (3) on its DC voltage side and is connected with at least one arc electrode (5) on its AC voltage side. In order to improve a generation of stable and uniform arcs, the above inverter (4) is designed to give a rectangular AC voltage to the arc electrode (5). COPYRIGHT: (C)2008,JPO&INPIT
Abstract:
PROBLEM TO BE SOLVED: To provide a power semiconductor device, having a control electrode which influences a semiconductor parameter, and especially a power diode. SOLUTION: The power semiconductor device is provided with a pn junction between two sets of power electrodes (2, 3). The control electrode (4) is arranged in the region of the power electrode (3). A current, passing through the power electrode, is increased by supplying a current from the control electrode. As a result, a reverse current in a inhibit status of the device is increased. According to this constitution, a plurality of the power semiconductor devices are connected in series without using a snubber circuit for protection against an overvoltage. COPYRIGHT: (C)2004,JPO
Abstract:
PROBLEM TO BE SOLVED: To provide a method for improving and simplifying the monitoring of a current transformer in a switchgear, and to provide a computer program, a device and the switchgear provided with the device. SOLUTION: The instantaneous topology of the switchgear is grasped by a facility management system based on the existing electrical connection of the primary device and the instantaneous position of a switch (a), at least one zone of the switchgear is identified based on the instantaneous topology, while the zone is a region that is partitioned by at least one current transformer, in some cases, by the opened switch, and conductivity connected (b), in the zone, a measurement signal of the current transformer is detected by using a code that depends on the direction of a current and added to the total current of the zone (c), and, when the total current is not equal to zero in the allowable range of the measurement accuracy of the current transformer, all current transformers in related zones are identified to have problems (d). COPYRIGHT: (C)2004,JPO
Abstract:
PROBLEM TO BE SOLVED: To enable the optimum operation of an IGDT by being adapted to the characteristics of the IGDT. SOLUTION: An integrated gate dual transistor (IGDT) is equipped with controllable gates (G1 and G2), a first gate (G1) that is supplied to a cathode side and at the same time is driven by a first gate current via a first gate terminal having low inductance, and a second gate (G2) that is supplied to an anode side and at the same time is driven by a second gate current via a second gate terminal with low inductance. In the switch-off operation of the IGDT, the rate of rising in the voltage of the IGDT is restricted via the two gates. The restriction of the rate of rising in the voltage of the IGDT prevents the voltage from being increased at a different speed in the series circuit of the IGDT, thus preventing the overheat and breakdown of each IGDT due to a nonuniform load. COPYRIGHT: (C)2003,JPO
Abstract:
PROBLEM TO BE SOLVED: To make substantially constant an intermediate circuit voltage by a three-point DC voltage middle circuit. SOLUTION: A converter circuit facility is the one for matching a variable DC voltage to a drive circuit, making a drive signal, and having a three-point DC voltage middle circuit (2). The three-point DC voltage middle circuit (2) is made of a first capacitor (3) and a second capacitor (4) connected in series with it, one connection of the first capacitor (3) forms the upper connection (5) of the three-point DC voltage middle circuit (2), the first capacitor (3) forms a center point connection (6) at the junction with the second capacitor (4), and one connection of the second capacitor (4) forms the lower connection (7) of the three-point DC voltage intermediate circuit (2).
Abstract:
PROBLEM TO BE SOLVED: To provide a combustor for especially driving a gas turbine in which instability of combustion can be suppressed while keeping a simple and reliable function by improving a combustor of such a type as having a large number of burners of identical thermal power output working in common combustion chambers in parallel with the axis. SOLUTION: A large number of burners 12, 13, 14, 15 are arranged differently such that flames 24, 25, 26, 27 produced therefrom or the flame fronts thereof are positioned to be distributed along the axis 28.