摘要:
A control circuit for a semiconductor element with a control electrode includes a signal transmission circuit, in which two switching elements made conductive when a control signal is supplied from a control signal source to the switching elements through a signal insulating element, are provided so that the control signal is transferred to a turn-on circuit for the semiconductor element only when the switching elements are simultaneously made conductive.
摘要:
A gate circuit for gate turn-off thyristors is disclosed which includes a turn-on circuit formed of a series combination of a turn-on power source and an NPN transistor and a turn-off circuit formed of a series combination of a turn-off power source and a thyristor, and in which a PNP transistor is provided between the anode and gate of the thyristor in such a manner that the base of the NPN transistor and the base of the PNP transistor are connected to each other and a junction of these bases receives a control signal for turning on or off a gate turn-off thyristor.
摘要:
Shortcircuit in an arm including a series connection of GTO's and reactors of an inverter is detected by sensing a voltage across the reactor. In one method, the shortcircuit in the arm is detected when voltages are coincidently applied to a P-line arm reactor and an N-line arm reactor for a predetermined time period. In another method, it is detected when an integrated value of a voltage across at least one of the reactors exceeds a predetermined level.
摘要:
In the control of a synchronous motor driven by a power converter of voltage source type, the phase of the current flowing into the motor is detected and gate signals are produced on the basis of the phase of the current, so that the output frequency of the power converter is controlled by the gate signals so as to control the motor.
摘要:
When a power conversion apparatus such as inverter or chopper comprises gate turn-off thyristors (GTO's), current limiting reactors are connected to cathodes of the GTO's and opposite ends of each of the reactors are connected to positive and negative terminals, respectively, of a gate power supply which supplies a turn-on current and a turn-off current to the respective GTO. With this arrangement, an energy stored in each of the reactors at the turn-off of the GTO is absorbed by the gate power supply.
摘要:
A control device for a pulse-width modulated inverter comprises means for generating as a carrier wave a triangular wave synchronizing with an AC output from the inverter, means for generating as a modulating wave a train of rectangular wave pulses which synchronize with the triangular wave and have a width corresponding to a section effective for a modulating operation and a predetermined amplitude, voltage level setting means for setting the amplitude of the train of rectangular wave pulses, and means for modulating the triangular wave with the train of rectangular wave pulses and generating a control pulse for the AC output. The rectangular wave pulses are so set as to have a modulating level of zero in the proximity of a point corresponding to the zero point of the AC output of each phase thereby to remove a frequency divider for adjusting input frequencies of the triangular wave generating means and the modulating wave generating means and to prevent a useless modulating operation leading only to an increase in the number of commutations of the inverter.
摘要:
A method and an apparatus for controlling the operation of the synchronous motor are disclosed in which the synchronous motor is started with a starting power supply and operated with a steadying power supply. The starting power supply is adapted to alternately repeat acceleration and deceleration of the synchronous motor in the neighborhood of the frequency thereby to bring the synchronous motor into the point where the synchronous motor is in synchronism with the steadying power supply. The starting power supply comprises a current control circuit and a phase angle control circuit, which circuits control the motor current in such a manner as to prevent the voltage drop due to the synchronous reactance of the motor from exceeding the induced voltage of the motor, while at the same time controlling the power factor angle to be in the range from a lead 90.degree. to the angle corresponding to a maximum output point produced by said motor current.
摘要:
In order to provide a motor characterized by a high level of efficiency equal to or better than that of using the silicon steel plate, achieved by easy production method and reduced core loss, which result from reduction in the manpower for production by using the sintered metal or powdered iron core in at least one of the stator and rotor, the present invention provides a motor comprising a stator and a rotor wherein either one of said stator or rotor has a magnet, and the other has a magnetic substance. This motor is further characterized in that the main magnetic flux flowing between the stator and rotor changes in the three-dimensional directions according to the magnetic structure of this motor, and at least part of said magnetic substance is composed of an aggregate of magnetic powder.
摘要:
A coated glass fiber for light transmission consisting of a glass fiber for light transmission and at least one coating layer made of a UV-curing resin, wherein an outermost layer of the coating layer is made of a UV-curing resin having a Young's modulus of at least 100 kg/mm.sup.2 and a change of a cure shrinkage degree of 1% or less after a Young's modulus reaches one tenth of an end Young's modulus, which has good lateral pressure characteristics and low transmission loss.
摘要:
A process and an apparatus for producing a preform for plastic optical fiber having a refractive index distribution in which the refractive index is gradually decreased from the center of the preform toward the outer periphery thereof, by depositing a deposition layer comprising a polymer A (refractive index: N.sub.a) and a refractive index modifier having a refractive index different from that of the polymer A onto a surface of a rod member rotating about an axis thereof, by use of vapor-phase deposition based on a CVD (Chemical Vapor Deposition) process, or a coating process. A plastic optical fiber preform including deposition layers having a gradually decreasing refractive index distribution is formed by changing the mixing ratio between the polymer A and the refractive index modifier constituting the deposition layer.