Abstract: Stators 12 and 13 are disposed with required air gaps in an axial direction of a rotor 11 so as to face each other, a plurality of field bodies 15 or permanent magnets 33 are disposed in the rotor 11, and a plurality of armature coils 17 and 19 are disposed in the stators 12 and 13 around the axis. At least one of the field bodies 15 or permanent magnets 33 and the armature coils 17 and 19 are formed from a superconductive material such that their magnetic flux directions are directed to the axial direction.

Abstract: In a cooling structure of a superconducting motor in which a superconducting coil is attached to a rotor, grooves are concavely provided on an outer surface of a rotating shaft that penetrates and is fixed to the rotor. A refrigerant is circulated through a refrigerant circulation pipe disposed inside the grooves to that the superconducting coil is cooled by the refrigerant.

Abstract: A magnetizing device for superconductor and a superconducting synchronous machine are provided capable of constituting more compact and simple equipment that uses a superconductor as a magnet. The magnetizing device for superconductor includes a superconductor (131); a coolant chamber (142) for cooling the superconductor (131) down to or below a critical temperature at which the transition to a superconducting state occurs; coils (111, 111?) for generating a magnetic field equal to or higher than a critical magnetic field in which the intrusion of a magnetic flux into the superconductor (131) starts, around the superconductor (131) cooled down to or below the critical temperature at which the transition to the superconducting state occurs; and position modification means capable of arranging the superconductor (131) on a disk (120) and modifying the relative positional relationship with the coils (111, 111?).

Abstract: A piezoelectric transformer inverter includes: a piezoelectric transformer, one of whose primary electrodes is grounded, which performs voltage conversion of alternating voltage or direct current voltage applied between the primary electrodes and supplies the converted voltage to a load connected to a secondary electrode; a drive unit for supplying alternating voltage or direct current voltage between the primary electrodes of the piezoelectric transformer; a low-pass type resonance circuit unit inserted between the output of the drive unit and the primary electrodes of the piezoelectric transformer; a duty control unit for controlling ON-Duty of the drive unit so that a value of current flowing into the load coincides with a targeted current value; a phase-difference detection unit for detecting a phase difference between the input voltage and the output voltage of the piezoelectric transformer; and a frequency control unit for controlling a driving frequency of the drive unit.

Abstract: A power apparatus includes a compensator which is capable of enabling phase to lead as the frequency increases, even if gain increases, as shown in a Bode diagram, so as to operate stably. The power apparatus includes a power converter for controlling a voltage from a power source and supplying it to a load, a smoothing circuit which is connected between the power converter and the load, and a controller for controlling the power converter, wherein the controller is formed of an amplifier, first to seventh (or eighth) resistors, and first and second capacitors, arranged to provide specific transfer functions.

Abstract: A power supply includes a power converter 2 for generating an output voltage to be supplied to a load 3 from a power source 4, a filter 5 connected between power converter 2 and load 3, and a controller 10 for controlling the power converter 2, in which controller 10 applies a voltage instruction value v.sub.r applied as an input to circuitry which implements an operation element A defined as: ##EQU1## subtracts the output voltage from instruction voltage v.sub.r, and applies the difference to power converter 2.

Abstract: An improved support apparatus such as a suspension apparatus for a vehicle is disclosed which has excellent response characteristics, can save power consumption and has excellent vibration-isolating capacity for isolating the transmission of high-frequency vibrations from a support member such as a road wheel to an object such as the body of a vehicle. To these end, in one embodiment, a linear motor is disposed between the object and the support member for telescopically supporting the object under magnetic effects. A position sensor senses the position of the object relative to a reference position. A low-pass filter filters high-frequency components of the output signal of the position sensor above a prescribed upper frequency limit. Based on the output signals of the position sensor and the low-pass filter, the current supply to the linear motor is controlled in such a manner as to offset a change in the output signal of the low-pass filter.

Abstract: A linear motor elevation system comprising an elongated magnetic induction member (21) mounted along the hoistway. The induction member (21) has a plurality of magnetic poles (21a) disposed at equal intervals along the hoistway so that they face toward the armature (27). An elevator car (4) or a counter weight has attached thereto a field magnet (26) disposed in a facing relationship with respect to the magnetic induction member (21) for generating magnetic poles in the induction member (21). The field magnet (26) comprises an iron core (23) having a U-shaped cross section including a central web portion on which a field winding 24 is wound and parallel flange portions extending from the web portion toward the magnetic induction member (21).

Abstract: A controller for AC power converter having an LC filter connected to a load, can suppress fluctuation of the output bus voltage against disturbance, particularly against fluctuation of load current by calculating a capacitor current command from a voltage feed back value and then adding an interference component caused by a reactor and a capacitor to the voltage command of the AC power converter.

Abstract: A DC-DC converter comprises a switching element having a rise time t.sub.on and a fall time t.sub.off ; a control device for controlling the switching operation of the switching element; a transformer having a primary winding and a secondary winding, the primary winding being connected to a DC power source through the switching element, and having an open inductance L.sub.M ; an inductance coil having an inductance L connected to the secondary winding of the transformer; and a rectifying device for rectifying the output from the secondary winding of the transformer; assuming that the voltage applied to the primary winding of the transformer is E, the load current flowing through the transformer is I.sub.D, and the sum of the stray capacitance of the switching element and the distributed capacity of the windings of the transformer is C1, the following relational expressions being established:L>(E/I.sub.D)T.sub.onandL.sub.M >t.sub.off.sup.2 /.pi..sup.

Abstract: A method of operating a three-phase converter to produce a signal at an output frequency by decoupling and digitally sampling inverter input signals and load voltage signals and feeding the resultant phase signals back into the inverter. The phase voltages activate switching elements in the inverter to switch signals a plurality of times within one cycle of the output frequency thus changing electrical power at a first frequency, including direct current, to A.C. power at the output frequency.

Abstract: In an induction motor controller, for the amount equivalent to the secondary interlinkage flux computed by use of a component of lag of first order based on the search coil voltage or the primary voltage of the induction motor, an error with respect to the actual secondary interlinkage flux is increased in a low-speed range. However, since an estimated amount equivalent to the secondary interlinkage flux computed based on the estimated amount of the secondary interlinkage flux is also attended with the same error with respect to the secondary interlinkage flux, when the former is substracted from the latter, there only remains a term concerning the speed estimation error, which enables an estimation of the speed to be conducted also in the low-speed range.

Abstract: A 3-phase-to-3-phase power converter is intended to control the output voltage and current so as to provide a 3-phase sinusoidal wave which is controlled in compliance with the input voltage. The main circuit has a switching period shorter than 30.degree. of the power voltage waveform and it is controlled so that switching of lines takes place in alternate fashion, whereby the input power factor is improved.

Abstract: The present invention consists in connecting an auxiliary D.C. voltage source to a series-connected assembly constructed of electronic switches, whereby even when the electronic switches in the series-connected assembly have unequal switching rates, any overvoltage is not applied to the electronic switches and any power loss ascribable to the overvoltage is prevented.

Abstract: A control circuit 3 for an induction motor 2 detects the voltage applied across the motor winding and the current flowing therethrough. The supply power and the feedback power are determined from the detected voltage and current and are supplied to a computing unit whose output controls a voltage regulator such that the voltage applied across the motor winding results in a fixed, predetermined ratio between the effective and apparent powers to maximize the motor efficiency and to minimize the motor's power consumption regardless of variations in the line voltage and fluctuations in the motor load.

Abstract: An error amplifier is connected to both a tachometer generator for an induction motor and a command speed generator to produce an error signal corresponding to the difference between the actual motor speed and a command motor speed. A current limit generator connected to the tachometer generator generates a current limit signal which is subtracted from a motor current signal from a current sensor for the motor. A multiplier imparts to the resulting difference signal the polarity opposite to that of the error signal as determined by a polarity discriminator. The difference signal is added to the error and actual speed signals by an adder to form a command frequency signal. An inverter controls the motor in response to the command frequency signal.

Abstract: Economical thyristors are used instead of expensive transistors and a transistor is used for extinction of the thyristors to reduce cost in an inverter device having an inverter function for converting DC to AC or a current type inverter device having a chopper function for controlling DC power and an inverter function for converting DC to AC.

Abstract: An inverter device for converting DC to AC by using thyristors as switching elements comprises a commutation circuit for turn-off of the thyristors which is formed by a serial connection of an auxiliary power source, a gate control thyristor and a thyristor which is commonly used and connected to a thyristor used as the switching element which is turned off by applying a reverse voltage by turning on the gate control thyristor and the thyristor of the commutation circuit.